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3a92312953
options which provide more fine grained MaxStartups limits. Man page help jmc@, feedback & ok djm@ OpenBSD-Commit-ID: e2f68664e3d02c0895b35aa751c48a2af622047b
141 lines
3.8 KiB
C
141 lines
3.8 KiB
C
/*
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* Copyright (c) 2020 Darren Tucker <dtucker@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "includes.h"
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <limits.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <string.h>
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#include "addr.h"
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#include "canohost.h"
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#include "log.h"
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#include "misc.h"
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#include "srclimit.h"
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#include "xmalloc.h"
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static int max_children, max_persource, ipv4_masklen, ipv6_masklen;
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/* Per connection state, used to enforce unauthenticated connection limit. */
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static struct child_info {
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int id;
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struct xaddr addr;
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} *child;
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void
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srclimit_init(int max, int persource, int ipv4len, int ipv6len)
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{
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int i;
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max_children = max;
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ipv4_masklen = ipv4len;
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ipv6_masklen = ipv6len;
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max_persource = persource;
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if (max_persource == INT_MAX) /* no limit */
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return;
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debug("%s: max connections %d, per source %d, masks %d,%d", __func__,
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max, persource, ipv4len, ipv6len);
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if (max <= 0)
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fatal("%s: invalid number of sockets: %d", __func__, max);
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child = xcalloc(max_children, sizeof(*child));
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for (i = 0; i < max_children; i++)
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child[i].id = -1;
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}
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/* returns 1 if connection allowed, 0 if not allowed. */
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int
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srclimit_check_allow(int sock, int id)
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{
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struct xaddr xa, xb, xmask;
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struct sockaddr_storage addr;
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socklen_t addrlen = sizeof(addr);
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struct sockaddr *sa = (struct sockaddr *)&addr;
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int i, bits, first_unused, count = 0;
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char xas[NI_MAXHOST];
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if (max_persource == INT_MAX) /* no limit */
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return 1;
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debug("%s: sock %d id %d limit %d", __func__, sock, id, max_persource);
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if (getpeername(sock, sa, &addrlen) != 0)
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return 1; /* not remote socket? */
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if (addr_sa_to_xaddr(sa, addrlen, &xa) != 0)
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return 1; /* unknown address family? */
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/* Mask address off address to desired size. */
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bits = xa.af == AF_INET ? ipv4_masklen : ipv6_masklen;
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if (addr_netmask(xa.af, bits, &xmask) != 0 ||
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addr_and(&xb, &xa, &xmask) != 0) {
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debug3("%s: invalid mask %d bits", __func__, bits);
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return 1;
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}
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first_unused = max_children;
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/* Count matching entries and find first unused one. */
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for (i = 0; i < max_children; i++) {
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if (child[i].id == -1) {
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if (i < first_unused)
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first_unused = i;
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} else if (addr_cmp(&child[i].addr, &xb) == 0) {
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count++;
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}
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}
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if (addr_ntop(&xa, xas, sizeof(xas)) != 0) {
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debug3("%s: addr ntop failed", __func__);
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return 1;
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}
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debug3("%s: new unauthenticated connection from %s/%d, at %d of %d",
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__func__, xas, bits, count, max_persource);
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if (first_unused == max_children) { /* no free slot found */
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debug3("%s: no free slot", __func__);
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return 0;
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}
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if (first_unused < 0 || first_unused >= max_children)
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fatal("%s: internal error: first_unused out of range",
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__func__);
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if (count >= max_persource)
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return 0;
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/* Connection allowed, store masked address. */
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child[first_unused].id = id;
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memcpy(&child[first_unused].addr, &xb, sizeof(xb));
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return 1;
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}
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void
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srclimit_done(int id)
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{
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int i;
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if (max_persource == INT_MAX) /* no limit */
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return;
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debug("%s: id %d", __func__, id);
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/* Clear corresponding state entry. */
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for (i = 0; i < max_children; i++) {
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if (child[i].id == id) {
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child[i].id = -1;
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return;
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}
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}
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}
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