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upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
/*
* Copyright (c) 2020 Darren Tucker <dtucker@openbsd.org>
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
* Copyright (c) 2024 Damien Miller <djm@mindrot.org>
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/socket.h>
#include <sys/types.h>
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
#include <openbsd-compat/sys-tree.h>
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
#include <limits.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
#include <stdlib.h>
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
#include "addr.h"
#include "canohost.h"
#include "log.h"
#include "misc.h"
#include "srclimit.h"
#include "xmalloc.h"
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
#include "servconf.h"
#include "match.h"
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
static int max_children, max_persource, ipv4_masklen, ipv6_masklen;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
static struct per_source_penalty penalty_cfg;
static char *penalty_exempt;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
/* Per connection state, used to enforce unauthenticated connection limit. */
static struct child_info {
int id;
struct xaddr addr;
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
} *children;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
/*
* Penalised addresses, active entries here prohibit connections until expired.
* Entries become active when more than penalty_min seconds of penalty are
* outstanding.
*/
struct penalty {
struct xaddr addr;
time_t expiry;
int active;
const char *reason;
RB_ENTRY(penalty) by_addr;
RB_ENTRY(penalty) by_expiry;
};
static int penalty_addr_cmp(struct penalty *a, struct penalty *b);
static int penalty_expiry_cmp(struct penalty *a, struct penalty *b);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
RB_HEAD(penalties_by_addr, penalty) penalties_by_addr4, penalties_by_addr6;
RB_HEAD(penalties_by_expiry, penalty) penalties_by_expiry4, penalties_by_expiry6;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
RB_GENERATE_STATIC(penalties_by_addr, penalty, by_addr, penalty_addr_cmp)
RB_GENERATE_STATIC(penalties_by_expiry, penalty, by_expiry, penalty_expiry_cmp)
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
static size_t npenalties4, npenalties6;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
static int
srclimit_mask_addr(const struct xaddr *addr, int bits, struct xaddr *masked)
{
struct xaddr xmask;
/* Mask address off address to desired size. */
if (addr_netmask(addr->af, bits, &xmask) != 0 ||
addr_and(masked, addr, &xmask) != 0) {
debug3_f("%s: invalid mask %d bits", __func__, bits);
return -1;
}
return 0;
}
static int
srclimit_peer_addr(int sock, struct xaddr *addr)
{
struct sockaddr_storage storage;
socklen_t addrlen = sizeof(storage);
struct sockaddr *sa = (struct sockaddr *)&storage;
if (getpeername(sock, sa, &addrlen) != 0)
return 1; /* not remote socket? */
if (addr_sa_to_xaddr(sa, addrlen, addr) != 0)
return 1; /* unknown address family? */
return 0;
}
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
void
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
srclimit_init(int max, int persource, int ipv4len, int ipv6len,
struct per_source_penalty *penalty_conf, const char *penalty_exempt_conf)
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
{
int i;
max_children = max;
ipv4_masklen = ipv4len;
ipv6_masklen = ipv6len;
max_persource = persource;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
penalty_cfg = *penalty_conf;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (penalty_cfg.max_sources4 < 0 || penalty_cfg.max_sources6 < 0)
fatal_f("invalid max_sources"); /* shouldn't happen */
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
penalty_exempt = penalty_exempt_conf == NULL ?
NULL : xstrdup(penalty_exempt_conf);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
RB_INIT(&penalties_by_addr4);
RB_INIT(&penalties_by_expiry4);
RB_INIT(&penalties_by_addr6);
RB_INIT(&penalties_by_expiry6);
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
if (max_persource == INT_MAX) /* no limit */
return;
debug("%s: max connections %d, per source %d, masks %d,%d", __func__,
max, persource, ipv4len, ipv6len);
if (max <= 0)
fatal("%s: invalid number of sockets: %d", __func__, max);
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
children = xcalloc(max_children, sizeof(*children));
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
for (i = 0; i < max_children; i++)
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
children[i].id = -1;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
}
/* returns 1 if connection allowed, 0 if not allowed. */
int
srclimit_check_allow(int sock, int id)
{
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
struct xaddr xa, xb;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
int i, bits, first_unused, count = 0;
char xas[NI_MAXHOST];
if (max_persource == INT_MAX) /* no limit */
return 1;
debug("%s: sock %d id %d limit %d", __func__, sock, id, max_persource);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
if (srclimit_peer_addr(sock, &xa) != 0)
return 1;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
bits = xa.af == AF_INET ? ipv4_masklen : ipv6_masklen;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
if (srclimit_mask_addr(&xa, bits, &xb) != 0)
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
return 1;
first_unused = max_children;
/* Count matching entries and find first unused one. */
for (i = 0; i < max_children; i++) {
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
if (children[i].id == -1) {
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
if (i < first_unused)
first_unused = i;
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
} else if (addr_cmp(&children[i].addr, &xb) == 0) {
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
count++;
}
}
if (addr_ntop(&xa, xas, sizeof(xas)) != 0) {
debug3("%s: addr ntop failed", __func__);
return 1;
}
debug3("%s: new unauthenticated connection from %s/%d, at %d of %d",
upstream: highly polished whitespace, mostly fixing spaces-for-tab and bad indentation on continuation lines. Prompted by GHPR#185 OpenBSD-Commit-ID: e5c81f0cbdcc6144df1ce468ec1bac366d8ad6e9
2021-04-03 06:18:40 +00:00
__func__, xas, bits, count, max_persource);
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
if (first_unused == max_children) { /* no free slot found */
debug3("%s: no free slot", __func__);
return 0;
}
if (first_unused < 0 || first_unused >= max_children)
fatal("%s: internal error: first_unused out of range",
__func__);
if (count >= max_persource)
return 0;
/* Connection allowed, store masked address. */
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
children[first_unused].id = id;
memcpy(&children[first_unused].addr, &xb, sizeof(xb));
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
return 1;
}
void
srclimit_done(int id)
{
int i;
if (max_persource == INT_MAX) /* no limit */
return;
debug("%s: id %d", __func__, id);
/* Clear corresponding state entry. */
for (i = 0; i < max_children; i++) {
upstream: avoid shadowing issues which some compilers won't accept ok djm OpenBSD-Commit-ID: 1e89572397dda83433d58c4fa6333a08f51170d4
2024-06-07 13:23:30 +00:00
if (children[i].id == id) {
children[i].id = -1;
upstream: Add PerSourceMaxStartups and PerSourceNetBlockSize options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
2021-01-09 12:10:02 +00:00
return;
}
}
}
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
static int
penalty_addr_cmp(struct penalty *a, struct penalty *b)
{
return addr_cmp(&a->addr, &b->addr);
/* Addresses must be unique in by_addr, so no need to tiebreak */
}
static int
penalty_expiry_cmp(struct penalty *a, struct penalty *b)
{
if (a->expiry != b->expiry)
return a->expiry < b->expiry ? -1 : 1;
/* Tiebreak on addresses */
return addr_cmp(&a->addr, &b->addr);
}
static void
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
expire_penalties_from_tree(time_t now, const char *t,
struct penalties_by_expiry *by_expiry,
struct penalties_by_addr *by_addr, size_t *npenaltiesp)
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
{
struct penalty *penalty, *tmp;
/* XXX avoid full scan of tree, e.g. min-heap */
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
RB_FOREACH_SAFE(penalty, penalties_by_expiry, by_expiry, tmp) {
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
if (penalty->expiry >= now)
break;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (RB_REMOVE(penalties_by_expiry, by_expiry,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
penalty) != penalty ||
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
RB_REMOVE(penalties_by_addr, by_addr,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
penalty) != penalty)
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
fatal_f("internal error: %s penalty table corrupt", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
free(penalty);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if ((*npenaltiesp)-- == 0)
fatal_f("internal error: %s npenalties underflow", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
}
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
static void
expire_penalties(time_t now)
{
expire_penalties_from_tree(now, "ipv4",
&penalties_by_expiry4, &penalties_by_addr4, &npenalties4);
expire_penalties_from_tree(now, "ipv6",
&penalties_by_expiry6, &penalties_by_addr6, &npenalties6);
}
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
static void
addr_masklen_ntop(struct xaddr *addr, int masklen, char *s, size_t slen)
{
size_t o;
if (addr_ntop(addr, s, slen) != 0) {
strlcpy(s, "UNKNOWN", slen);
return;
}
if ((o = strlen(s)) < slen)
snprintf(s + o, slen - o, "/%d", masklen);
}
int
srclimit_penalty_check_allow(int sock, const char **reason)
{
struct xaddr addr;
struct penalty find, *penalty;
time_t now;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
int bits, max_sources, overflow_mode;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
char addr_s[NI_MAXHOST];
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
struct penalties_by_addr *by_addr;
size_t npenalties;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
if (!penalty_cfg.enabled)
return 1;
if (srclimit_peer_addr(sock, &addr) != 0)
return 1;
if (penalty_exempt != NULL) {
if (addr_ntop(&addr, addr_s, sizeof(addr_s)) != 0)
return 1; /* shouldn't happen */
if (addr_match_list(addr_s, penalty_exempt) == 1) {
return 1;
}
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
now = monotime();
expire_penalties(now);
by_addr = addr.af == AF_INET ?
&penalties_by_addr4 : &penalties_by_addr6;
max_sources = addr.af == AF_INET ?
penalty_cfg.max_sources4 : penalty_cfg.max_sources6;
overflow_mode = addr.af == AF_INET ?
penalty_cfg.overflow_mode : penalty_cfg.overflow_mode6;
npenalties = addr.af == AF_INET ? npenalties4 : npenalties6;
if (npenalties >= (size_t)max_sources &&
overflow_mode == PER_SOURCE_PENALTY_OVERFLOW_DENY_ALL) {
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
*reason = "too many penalised addresses";
return 0;
}
bits = addr.af == AF_INET ? ipv4_masklen : ipv6_masklen;
memset(&find, 0, sizeof(find));
if (srclimit_mask_addr(&addr, bits, &find.addr) != 0)
return 1;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if ((penalty = RB_FIND(penalties_by_addr, by_addr, &find)) == NULL)
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
return 1; /* no penalty */
if (penalty->expiry < now) {
expire_penalties(now);
return 1; /* expired penalty */
}
if (!penalty->active)
return 1; /* Penalty hasn't hit activation threshold yet */
*reason = penalty->reason;
return 0;
}
static void
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
srclimit_early_expire_penalties_from_tree(const char *t,
struct penalties_by_expiry *by_expiry,
struct penalties_by_addr *by_addr, size_t *npenaltiesp, size_t max_sources)
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
{
struct penalty *p = NULL;
int bits;
char s[NI_MAXHOST + 4];
/* Delete the soonest-to-expire penalties. */
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
while (*npenaltiesp > max_sources) {
if ((p = RB_MIN(penalties_by_expiry, by_expiry)) == NULL)
fatal_f("internal error: %s table corrupt (find)", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
bits = p->addr.af == AF_INET ? ipv4_masklen : ipv6_masklen;
addr_masklen_ntop(&p->addr, bits, s, sizeof(s));
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
debug3_f("%s overflow, remove %s", t, s);
if (RB_REMOVE(penalties_by_expiry, by_expiry, p) != p ||
RB_REMOVE(penalties_by_addr, by_addr, p) != p)
fatal_f("internal error: %s table corrupt (remove)", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
free(p);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
(*npenaltiesp)--;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
}
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
static void
srclimit_early_expire_penalties(void)
{
srclimit_early_expire_penalties_from_tree("ipv4",
&penalties_by_expiry4, &penalties_by_addr4, &npenalties4,
(size_t)penalty_cfg.max_sources4);
srclimit_early_expire_penalties_from_tree("ipv6",
&penalties_by_expiry6, &penalties_by_addr6, &npenalties6,
(size_t)penalty_cfg.max_sources6);
}
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
void
srclimit_penalise(struct xaddr *addr, int penalty_type)
{
struct xaddr masked;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
struct penalty *penalty = NULL, *existing = NULL;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
time_t now;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
int bits, penalty_secs, max_sources = 0, overflow_mode;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
char addrnetmask[NI_MAXHOST + 4];
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
const char *reason = NULL, *t;
size_t *npenaltiesp = NULL;
struct penalties_by_addr *by_addr = NULL;
struct penalties_by_expiry *by_expiry = NULL;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
if (!penalty_cfg.enabled)
return;
if (penalty_exempt != NULL) {
if (addr_ntop(addr, addrnetmask, sizeof(addrnetmask)) != 0)
return; /* shouldn't happen */
if (addr_match_list(addrnetmask, penalty_exempt) == 1) {
debug3_f("address %s is exempt", addrnetmask);
return;
}
}
switch (penalty_type) {
case SRCLIMIT_PENALTY_NONE:
return;
case SRCLIMIT_PENALTY_CRASH:
penalty_secs = penalty_cfg.penalty_crash;
reason = "penalty: caused crash";
break;
case SRCLIMIT_PENALTY_AUTHFAIL:
penalty_secs = penalty_cfg.penalty_authfail;
reason = "penalty: failed authentication";
break;
case SRCLIMIT_PENALTY_NOAUTH:
penalty_secs = penalty_cfg.penalty_noauth;
reason = "penalty: connections without attempting authentication";
break;
upstream: Add a "refuseconnection" penalty class to sshd_config PerSourcePenalties This allows penalising connection sources that have had connections dropped by the RefuseConnection option. ok markus@ OpenBSD-Commit-ID: 3c8443c427470bb3eac1880aa075cb4864463cb6
2024-09-15 01:11:26 +00:00
case SRCLIMIT_PENALTY_REFUSECONNECTION:
penalty_secs = penalty_cfg.penalty_refuseconnection;
reason = "penalty: connection prohibited by RefuseConnection";
break;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
case SRCLIMIT_PENALTY_GRACE_EXCEEDED:
penalty_secs = penalty_cfg.penalty_crash;
reason = "penalty: exceeded LoginGraceTime";
break;
default:
fatal_f("internal error: unknown penalty %d", penalty_type);
}
bits = addr->af == AF_INET ? ipv4_masklen : ipv6_masklen;
if (srclimit_mask_addr(addr, bits, &masked) != 0)
return;
addr_masklen_ntop(addr, bits, addrnetmask, sizeof(addrnetmask));
now = monotime();
expire_penalties(now);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
by_expiry = addr->af == AF_INET ?
&penalties_by_expiry4 : &penalties_by_expiry6;
by_addr = addr->af == AF_INET ?
&penalties_by_addr4 : &penalties_by_addr6;
max_sources = addr->af == AF_INET ?
penalty_cfg.max_sources4 : penalty_cfg.max_sources6;
overflow_mode = addr->af == AF_INET ?
penalty_cfg.overflow_mode : penalty_cfg.overflow_mode6;
npenaltiesp = addr->af == AF_INET ? &npenalties4 : &npenalties6;
t = addr->af == AF_INET ? "ipv4" : "ipv6";
upstream: stricter check for overfull tables in penalty record path OpenBSD-Commit-ID: 7df01e648a0723418c554e64a9f2b6d38db060a6
2024-06-20 00:18:05 +00:00
if (*npenaltiesp >= (size_t)max_sources &&
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
overflow_mode == PER_SOURCE_PENALTY_OVERFLOW_DENY_ALL) {
verbose_f("%s penalty table full, cannot penalise %s for %s", t,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
addrnetmask, reason);
return;
}
penalty = xcalloc(1, sizeof(*penalty));
penalty->addr = masked;
penalty->expiry = now + penalty_secs;
penalty->reason = reason;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if ((existing = RB_INSERT(penalties_by_addr, by_addr,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
penalty)) == NULL) {
/* penalty didn't previously exist */
if (penalty_secs > penalty_cfg.penalty_min)
penalty->active = 1;
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (RB_INSERT(penalties_by_expiry, by_expiry, penalty) != NULL)
fatal_f("internal error: %s penalty tables corrupt", t);
verbose_f("%s: new %s %s penalty of %d seconds for %s", t,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
addrnetmask, penalty->active ? "active" : "deferred",
penalty_secs, reason);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (++(*npenaltiesp) > (size_t)max_sources)
srclimit_early_expire_penalties(); /* permissive */
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
return;
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
debug_f("%s penalty for %s %s already exists, %lld seconds remaining",
existing->active ? "active" : "inactive", t,
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
addrnetmask, (long long)(existing->expiry - now));
/* Expiry information is about to change, remove from tree */
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (RB_REMOVE(penalties_by_expiry, by_expiry, existing) != existing)
fatal_f("internal error: %s penalty table corrupt (remove)", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
/* An entry already existed. Accumulate penalty up to maximum */
existing->expiry += penalty_secs;
if (existing->expiry - now > penalty_cfg.penalty_max)
existing->expiry = now + penalty_cfg.penalty_max;
if (existing->expiry - now > penalty_cfg.penalty_min &&
!existing->active) {
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
verbose_f("%s: activating %s penalty of %lld seconds for %s",
addrnetmask, t, (long long)(existing->expiry - now),
reason);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
existing->active = 1;
}
existing->reason = penalty->reason;
free(penalty);
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
penalty = NULL;
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
/* Re-insert into expiry tree */
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
if (RB_INSERT(penalties_by_expiry, by_expiry, existing) != NULL)
fatal_f("internal error: %s penalty table corrupt (insert)", t);
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
static void
srclimit_penalty_info_for_tree(const char *t,
struct penalties_by_expiry *by_expiry, size_t npenalties)
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
{
struct penalty *p = NULL;
int bits;
char s[NI_MAXHOST + 4];
time_t now;
now = monotime();
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
logit("%zu active %s penalties", npenalties, t);
RB_FOREACH(p, penalties_by_expiry, by_expiry) {
upstream: Add a facility to sshd(8) to penalise particular problematic client behaviours, controlled by two new sshd_config(5) options: PerSourcePenalties and PerSourcePenaltyExemptList. When PerSourcePenalties are enabled, sshd(8) will monitor the exit status of its child pre-auth session processes. Through the exit status, it can observe situations where the session did not authenticate as expected. These conditions include when the client repeatedly attempted authentication unsucessfully (possibly indicating an attack against one or more accounts, e.g. password guessing), or when client behaviour caused sshd to crash (possibly indicating attempts to exploit sshd). When such a condition is observed, sshd will record a penalty of some duration (e.g. 30 seconds) against the client's address. If this time is above a minimum threshold specified by the PerSourcePenalties, then connections from the client address will be refused (along with any others in the same PerSourceNetBlockSize CIDR range). Repeated offenses by the same client address will accrue greater penalties, up to a configurable maximum. A PerSourcePenaltyExemptList option allows certain address ranges to be exempt from all penalties. We hope these options will make it significantly more difficult for attackers to find accounts with weak/guessable passwords or exploit bugs in sshd(8) itself. PerSourcePenalties is off by default, but we expect to enable it automatically in the near future. much feedback markus@ and others, ok markus@ OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-06 17:15:25 +00:00
bits = p->addr.af == AF_INET ? ipv4_masklen : ipv6_masklen;
addr_masklen_ntop(&p->addr, bits, s, sizeof(s));
if (p->expiry < now)
logit("client %s %s (expired)", s, p->reason);
else {
logit("client %s %s (%llu secs left)", s, p->reason,
(long long)(p->expiry - now));
}
}
}
upstream: split PerSourcePenalties address tracking. Previously it used one shared table and overflow policy for IPv4 and IPv6 addresses, now it will use separate tables and optionally different overflow policies. This prevents misbehaviour from IPv6 addresses (which are vastly easier to obtain many of) from affecting IPv4 connections and may allow for stricter overflow policies. ok deraadt@ OpenBSD-Commit-ID: 12637ed0aa4d5f1f3e702da42ea967cbd8bfdfd9
2024-06-12 22:36:00 +00:00
void
srclimit_penalty_info(void)
{
srclimit_penalty_info_for_tree("ipv4",
&penalties_by_expiry4, npenalties4);
srclimit_penalty_info_for_tree("ipv6",
&penalties_by_expiry6, npenalties6);
}