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4265215d73
openssh/sshconnect2.c
djm@openbsd.org 4265215d73 upstream: Client-side workaround for a bug in OpenSSH 7.4: this release 
allows RSA/SHA2 signatures for public key authentication but fails to
advertise this correctly via SSH2_MSG_EXT_INFO. This causes clients of these
server to incorrectly match PubkeyAcceptedAlgorithms and potentially refuse
to offer valid keys.

Reported by and based on patch from Gordon Messmer via bz3213, thanks
also for additional analysis by Jakub Jelen. ok dtucker

OpenBSD-Commit-ID: d6d0b7351d5d44c45f3daaa26efac65847a564f7
2021-06-06 13:41:36 +10:00

2332 lines
64 KiB
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/* $OpenBSD: sshconnect2.c,v 1.348 2021/06/06 03:40:39 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
* Copyright (c) 2008 Damien Miller. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
#include <vis.h>
#endif
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "sshbuf.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
#include "sshkey.h"
#include "kex.h"
#include "myproposal.h"
#include "sshconnect.h"
#include "authfile.h"
#include "dh.h"
#include "authfd.h"
#include "log.h"
#include "misc.h"
#include "readconf.h"
#include "match.h"
#include "dispatch.h"
#include "canohost.h"
#include "msg.h"
#include "pathnames.h"
#include "uidswap.h"
#include "hostfile.h"
#include "ssherr.h"
#include "utf8.h"
#include "ssh-sk.h"
#include "sk-api.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
/* import */
extern char *client_version_string;
extern char *server_version_string;
extern Options options;
/*
* SSH2 key exchange
*/
static char *xxx_host;
static struct sockaddr *xxx_hostaddr;
static const struct ssh_conn_info *xxx_conn_info;
static int
verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
{
if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
xxx_conn_info) == -1)
fatal("Host key verification failed.");
return 0;
}
/* Returns the first item from a comma-separated algorithm list */
static char *
first_alg(const char *algs)
{
char *ret, *cp;
ret = xstrdup(algs);
if ((cp = strchr(ret, ',')) != NULL)
*cp = '\0';
return ret;
}
static char *
order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port,
const struct ssh_conn_info *cinfo)
{
char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL;
char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL;
size_t maxlen;
struct hostkeys *hostkeys = NULL;
int ktype;
u_int i;
/* Find all hostkeys for this hostname */
get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
hostkeys = init_hostkeys();
for (i = 0; i < options.num_user_hostfiles; i++)
load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0);
for (i = 0; i < options.num_system_hostfiles; i++) {
load_hostkeys(hostkeys, hostname,
options.system_hostfiles[i], 0);
}
if (options.known_hosts_command != NULL) {
load_hostkeys_command(hostkeys, options.known_hosts_command,
"ORDER", cinfo, NULL, host);
}
/*
* If a plain public key exists that matches the type of the best
* preference HostkeyAlgorithms, then use the whole list as is.
* Note that we ignore whether the best preference algorithm is a
* certificate type, as sshconnect.c will downgrade certs to
* plain keys if necessary.
*/
best = first_alg(options.hostkeyalgorithms);
if (lookup_key_in_hostkeys_by_type(hostkeys,
sshkey_type_plain(sshkey_type_from_name(best)),
sshkey_ecdsa_nid_from_name(best), NULL)) {
debug3_f("have matching best-preference key type %s, "
"using HostkeyAlgorithms verbatim", best);
ret = xstrdup(options.hostkeyalgorithms);
goto out;
}
/*
* Otherwise, prefer the host key algorithms that match known keys
* while keeping the ordering of HostkeyAlgorithms as much as possible.
*/
oavail = avail = xstrdup(options.hostkeyalgorithms);
maxlen = strlen(avail) + 1;
first = xmalloc(maxlen);
last = xmalloc(maxlen);
*first = *last = '\0';
#define ALG_APPEND(to, from) \
do { \
if (*to != '\0') \
strlcat(to, ",", maxlen); \
strlcat(to, from, maxlen); \
} while (0)
while ((alg = strsep(&avail, ",")) && *alg != '\0') {
if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
fatal_f("unknown alg %s", alg);
/*
* If we have a @cert-authority marker in known_hosts then
* prefer all certificate algorithms.
*/
if (sshkey_type_is_cert(ktype) &&
lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
ALG_APPEND(first, alg);
continue;
}
/* If the key appears in known_hosts then prefer it */
if (lookup_key_in_hostkeys_by_type(hostkeys,
sshkey_type_plain(ktype),
sshkey_ecdsa_nid_from_name(alg), NULL)) {
ALG_APPEND(first, alg);
continue;
}
/* Otherwise, put it last */
ALG_APPEND(last, alg);
}
#undef ALG_APPEND
xasprintf(&ret, "%s%s%s", first,
(*first == '\0' || *last == '\0') ? "" : ",", last);
if (*first != '\0')
debug3_f("prefer hostkeyalgs: %s", first);
else
debug3_f("no algorithms matched; accept original");
out:
free(best);
free(first);
free(last);
free(hostname);
free(oavail);
free_hostkeys(hostkeys);
return ret;
}
void
ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
const struct ssh_conn_info *cinfo)
{
char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
char *s, *all_key;
int r, use_known_hosts_order = 0;
xxx_host = host;
xxx_hostaddr = hostaddr;
xxx_conn_info = cinfo;
/*
* If the user has not specified HostkeyAlgorithms, or has only
* appended or removed algorithms from that list then prefer algorithms
* that are in the list that are supported by known_hosts keys.
*/
if (options.hostkeyalgorithms == NULL ||
options.hostkeyalgorithms[0] == '-' ||
options.hostkeyalgorithms[0] == '+')
use_known_hosts_order = 1;
/* Expand or fill in HostkeyAlgorithms */
all_key = sshkey_alg_list(0, 0, 1, ',');
if ((r = kex_assemble_names(&options.hostkeyalgorithms,
kex_default_pk_alg(), all_key)) != 0)
fatal_fr(r, "kex_assemble_namelist");
free(all_key);
if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
fatal_f("kex_names_cat");
myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, s);
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
compat_cipher_proposal(ssh, options.ciphers);
myproposal[PROPOSAL_ENC_ALGS_STOC] =
compat_cipher_proposal(ssh, options.ciphers);
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
myproposal[PROPOSAL_COMP_ALGS_STOC] =
(char *)compression_alg_list(options.compression);
myproposal[PROPOSAL_MAC_ALGS_CTOS] =
myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
if (use_known_hosts_order) {
/* Query known_hosts and prefer algorithms that appear there */
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(ssh,
order_hostkeyalgs(host, hostaddr, port, cinfo));
} else {
/* Use specified HostkeyAlgorithms exactly */
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(ssh, options.hostkeyalgorithms);
}
if (options.rekey_limit || options.rekey_interval)
ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
options.rekey_interval);
/* start key exchange */
if ((r = kex_setup(ssh, myproposal)) != 0)
fatal_r(r, "kex_setup");
#ifdef WITH_OPENSSL
ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
# ifdef OPENSSL_HAS_ECC
ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
# endif
#endif
ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
ssh->kex->verify_host_key=&verify_host_key_callback;
ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
/* remove ext-info from the KEX proposals for rekeying */
myproposal[PROPOSAL_KEX_ALGS] =
compat_kex_proposal(ssh, options.kex_algorithms);
if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
fatal_r(r, "kex_prop2buf");
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
(r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal_fr(r, "send packet");
#endif
}
/*
* Authenticate user
*/
typedef struct cauthctxt Authctxt;
typedef struct cauthmethod Authmethod;
typedef struct identity Identity;
typedef struct idlist Idlist;
struct identity {
TAILQ_ENTRY(identity) next;
int agent_fd; /* >=0 if agent supports key */
struct sshkey *key; /* public/private key */
char *filename; /* comment for agent-only keys */
int tried;
int isprivate; /* key points to the private key */
int userprovided;
};
TAILQ_HEAD(idlist, identity);
struct cauthctxt {
const char *server_user;
const char *local_user;
const char *host;
const char *service;
struct cauthmethod *method;
sig_atomic_t success;
char *authlist;
#ifdef GSSAPI
/* gssapi */
gss_OID_set gss_supported_mechs;
u_int mech_tried;
#endif
/* pubkey */
struct idlist keys;
int agent_fd;
/* hostbased */
Sensitive *sensitive;
char *oktypes, *ktypes;
const char *active_ktype;
/* kbd-interactive */
int info_req_seen;
int attempt_kbdint;
/* password */
int attempt_passwd;
/* generic */
void *methoddata;
};
struct cauthmethod {
char *name; /* string to compare against server's list */
int (*userauth)(struct ssh *ssh);
void (*cleanup)(struct ssh *ssh);
int *enabled; /* flag in option struct that enables method */
int *batch_flag; /* flag in option struct that disables method */
};
static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
static int input_userauth_ext_info(int, u_int32_t, struct ssh *);
static int input_userauth_success(int, u_int32_t, struct ssh *);
static int input_userauth_failure(int, u_int32_t, struct ssh *);
static int input_userauth_banner(int, u_int32_t, struct ssh *);
static int input_userauth_error(int, u_int32_t, struct ssh *);
static int input_userauth_info_req(int, u_int32_t, struct ssh *);
static int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
static int userauth_none(struct ssh *);
static int userauth_pubkey(struct ssh *);
static int userauth_passwd(struct ssh *);
static int userauth_kbdint(struct ssh *);
static int userauth_hostbased(struct ssh *);
#ifdef GSSAPI
static int userauth_gssapi(struct ssh *);
static void userauth_gssapi_cleanup(struct ssh *);
static int input_gssapi_response(int type, u_int32_t, struct ssh *);
static int input_gssapi_token(int type, u_int32_t, struct ssh *);
static int input_gssapi_error(int, u_int32_t, struct ssh *);
static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
#endif
void userauth(struct ssh *, char *);
static void pubkey_cleanup(struct ssh *);
static int sign_and_send_pubkey(struct ssh *ssh, Identity *);
static void pubkey_prepare(Authctxt *);
static void pubkey_reset(Authctxt *);
static struct sshkey *load_identity_file(Identity *);
static Authmethod *authmethod_get(char *authlist);
static Authmethod *authmethod_lookup(const char *name);
static char *authmethods_get(void);
Authmethod authmethods[] = {
#ifdef GSSAPI
{"gssapi-with-mic",
userauth_gssapi,
userauth_gssapi_cleanup,
&options.gss_authentication,
NULL},
#endif
{"hostbased",
userauth_hostbased,
NULL,
&options.hostbased_authentication,
NULL},
{"publickey",
userauth_pubkey,
NULL,
&options.pubkey_authentication,
NULL},
{"keyboard-interactive",
userauth_kbdint,
NULL,
&options.kbd_interactive_authentication,
&options.batch_mode},
{"password",
userauth_passwd,
NULL,
&options.password_authentication,
&options.batch_mode},
{"none",
userauth_none,
NULL,
NULL,
NULL},
{NULL, NULL, NULL, NULL, NULL}
};
void
ssh_userauth2(struct ssh *ssh, const char *local_user,
const char *server_user, char *host, Sensitive *sensitive)
{
Authctxt authctxt;
int r;
if (options.challenge_response_authentication)
options.kbd_interactive_authentication = 1;
if (options.preferred_authentications == NULL)
options.preferred_authentications = authmethods_get();
/* setup authentication context */
memset(&authctxt, 0, sizeof(authctxt));
authctxt.server_user = server_user;
authctxt.local_user = local_user;
authctxt.host = host;
authctxt.service = "ssh-connection"; /* service name */
authctxt.success = 0;
authctxt.method = authmethod_lookup("none");
authctxt.authlist = NULL;
authctxt.methoddata = NULL;
authctxt.sensitive = sensitive;
authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
authctxt.info_req_seen = 0;
authctxt.attempt_kbdint = 0;
authctxt.attempt_passwd = 0;
#if GSSAPI
authctxt.gss_supported_mechs = NULL;
authctxt.mech_tried = 0;
#endif
authctxt.agent_fd = -1;
pubkey_prepare(&authctxt);
if (authctxt.method == NULL) {
fatal_f("internal error: cannot send userauth none request");
}
if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
ssh->authctxt = &authctxt;
ssh_dispatch_init(ssh, &input_userauth_error);
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */
pubkey_cleanup(ssh);
ssh->authctxt = NULL;
ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
if (!authctxt.success)
fatal("Authentication failed.");
debug("Authentication succeeded (%s).", authctxt.method->name);
}
/* ARGSUSED */
static int
input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
{
int r;
if (ssh_packet_remaining(ssh) > 0) {
char *reply;
if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
goto out;
debug2("service_accept: %s", reply);
free(reply);
} else {
debug2("buggy server: service_accept w/o service");
}
if ((r = sshpkt_get_end(ssh)) != 0)
goto out;
debug("SSH2_MSG_SERVICE_ACCEPT received");
/* initial userauth request */
userauth_none(ssh);
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
r = 0;
out:
return r;
}
/* ARGSUSED */
static int
input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
{
return kex_input_ext_info(type, seqnr, ssh);
}
void
userauth(struct ssh *ssh, char *authlist)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
authctxt->method->cleanup(ssh);
free(authctxt->methoddata);
authctxt->methoddata = NULL;
if (authlist == NULL) {
authlist = authctxt->authlist;
} else {
free(authctxt->authlist);
authctxt->authlist = authlist;
}
for (;;) {
Authmethod *method = authmethod_get(authlist);
if (method == NULL)
fatal("%s@%s: Permission denied (%s).",
authctxt->server_user, authctxt->host, authlist);
authctxt->method = method;
/* reset the per method handler */
ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
/* and try new method */
if (method->userauth(ssh) != 0) {
debug2("we sent a %s packet, wait for reply", method->name);
break;
} else {
debug2("we did not send a packet, disable method");
method->enabled = NULL;
}
}
}
/* ARGSUSED */
static int
input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
{
fatal_f("bad message during authentication: type %d", type);
return 0;
}
/* ARGSUSED */
static int
input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
{
char *msg = NULL;
size_t len;
int r;
debug3_f("entering");
if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
(r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
goto out;
if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
fmprintf(stderr, "%s", msg);
r = 0;
out:
free(msg);
return r;
}
/* ARGSUSED */
static int
input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
if (authctxt == NULL)
fatal_f("no authentication context");
free(authctxt->authlist);
authctxt->authlist = NULL;
if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
authctxt->method->cleanup(ssh);
free(authctxt->methoddata);
authctxt->methoddata = NULL;
authctxt->success = 1; /* break out */
return 0;
}
#if 0
static int
input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
if (authctxt == NULL)
fatal_f("no authentication context");
fatal("Unexpected authentication success during %s.",
authctxt->method->name);
return 0;
}
#endif
/* ARGSUSED */
static int
input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *authlist = NULL;
u_char partial;
if (authctxt == NULL)
fatal("input_userauth_failure: no authentication context");
if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
sshpkt_get_u8(ssh, &partial) != 0 ||
sshpkt_get_end(ssh) != 0)
goto out;
if (partial != 0) {
verbose("Authenticated with partial success.");
/* reset state */
pubkey_reset(authctxt);
}
debug("Authentications that can continue: %s", authlist);
userauth(ssh, authlist);
authlist = NULL;
out:
free(authlist);
return 0;
}
/*
* Format an identity for logging including filename, key type, fingerprint
* and location (agent, etc.). Caller must free.
*/
static char *
format_identity(Identity *id)
{
char *fp = NULL, *ret = NULL;
const char *note = "";
if (id->key != NULL) {
fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
SSH_FP_DEFAULT);
}
if (id->key) {
if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
note = " token";
else if (sshkey_is_sk(id->key))
note = " authenticator";
}
xasprintf(&ret, "%s %s%s%s%s%s%s",
id->filename,
id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
fp ? fp : "",
id->userprovided ? " explicit" : "", note,
id->agent_fd != -1 ? " agent" : "");
free(fp);
return ret;
}
/* ARGSUSED */
static int
input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
struct sshkey *key = NULL;
Identity *id = NULL;
int pktype, found = 0, sent = 0;
size_t blen;
char *pkalg = NULL, *fp = NULL, *ident = NULL;
u_char *pkblob = NULL;
int r;
if (authctxt == NULL)
fatal("input_userauth_pk_ok: no authentication context");
if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto done;
if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
debug_f("server sent unknown pkalg %s", pkalg);
goto done;
}
if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
debug_r(r, "no key from blob. pkalg %s", pkalg);
goto done;
}
if (key->type != pktype) {
error("input_userauth_pk_ok: type mismatch "
"for decoded key (received %d, expected %d)",
key->type, pktype);
goto done;
}
/*
* search keys in the reverse order, because last candidate has been
* moved to the end of the queue. this also avoids confusion by
* duplicate keys
*/
TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
if (sshkey_equal(key, id->key)) {
found = 1;
break;
}
}
if (!found || id == NULL) {
fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT);
error_f("server replied with unknown key: %s %s",
sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
goto done;
}
ident = format_identity(id);
debug("Server accepts key: %s", ident);
sent = sign_and_send_pubkey(ssh, id);
r = 0;
done:
sshkey_free(key);
free(ident);
free(fp);
free(pkalg);
free(pkblob);
/* try another method if we did not send a packet */
if (r == 0 && sent == 0)
userauth(ssh, NULL);
return r;
}
#ifdef GSSAPI
static int
userauth_gssapi(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
Gssctxt *gssctxt = NULL;
OM_uint32 min;
int r, ok = 0;
gss_OID mech = NULL;
/* Try one GSSAPI method at a time, rather than sending them all at
* once. */
if (authctxt->gss_supported_mechs == NULL)
gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
/* Check to see whether the mechanism is usable before we offer it */
while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
!ok) {
mech = &authctxt->gss_supported_mechs->
elements[authctxt->mech_tried];
/* My DER encoding requires length<128 */
if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
mech, authctxt->host)) {
ok = 1; /* Mechanism works */
} else {
authctxt->mech_tried++;
}
}
if (!ok || mech == NULL)
return 0;
authctxt->methoddata=(void *)gssctxt;
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_u32(ssh, 1)) != 0 ||
(r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
(r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
(r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
(r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
authctxt->mech_tried++; /* Move along to next candidate */
return 1;
}
static void
userauth_gssapi_cleanup(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
ssh_gssapi_delete_ctx(&gssctxt);
authctxt->methoddata = NULL;
free(authctxt->gss_supported_mechs);
authctxt->gss_supported_mechs = NULL;
}
static OM_uint32
process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
{
Authctxt *authctxt = ssh->authctxt;
Gssctxt *gssctxt = authctxt->methoddata;
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
gss_buffer_desc gssbuf;
OM_uint32 status, ms, flags;
int r;
status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
recv_tok, &send_tok, &flags);
if (send_tok.length > 0) {
u_char type = GSS_ERROR(status) ?
SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
if ((r = sshpkt_start(ssh, type)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send %u packet", type);
gss_release_buffer(&ms, &send_tok);
}
if (status == GSS_S_COMPLETE) {
/* send either complete or MIC, depending on mechanism */
if (!(flags & GSS_C_INTEG_FLAG)) {
if ((r = sshpkt_start(ssh,
SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send completion");
} else {
struct sshbuf *b;
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
ssh_gssapi_buildmic(b, authctxt->server_user,
authctxt->service, "gssapi-with-mic",
ssh->kex->session_id);
if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
fatal_f("sshbuf_mutable_ptr failed");
gssbuf.length = sshbuf_len(b);
status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
if (!GSS_ERROR(status)) {
if ((r = sshpkt_start(ssh,
SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
(r = sshpkt_put_string(ssh, mic.value,
mic.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send MIC");
}
sshbuf_free(b);
gss_release_buffer(&ms, &mic);
}
}
return status;
}
/* ARGSUSED */
static int
input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
Gssctxt *gssctxt;
size_t oidlen;
u_char *oidv = NULL;
int r;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
gssctxt = authctxt->methoddata;
/* Setup our OID */
if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
goto done;
if (oidlen <= 2 ||
oidv[0] != SSH_GSS_OIDTYPE ||
oidv[1] != oidlen - 2) {
debug("Badly encoded mechanism OID received");
userauth(ssh, NULL);
goto ok;
}
if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
fatal("Server returned different OID than expected");
if ((r = sshpkt_get_end(ssh)) != 0)
goto done;
if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
/* Start again with next method on list */
debug("Trying to start again");
userauth(ssh, NULL);
goto ok;
}
ok:
r = 0;
done:
free(oidv);
return r;
}
/* ARGSUSED */
static int
input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
gss_buffer_desc recv_tok;
u_char *p = NULL;
size_t len;
OM_uint32 status;
int r;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
recv_tok.value = p;
recv_tok.length = len;
status = process_gssapi_token(ssh, &recv_tok);
/* Start again with the next method in the list */
if (GSS_ERROR(status)) {
userauth(ssh, NULL);
/* ok */
}
r = 0;
out:
free(p);
return r;
}
/* ARGSUSED */
static int
input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
Gssctxt *gssctxt;
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
gss_buffer_desc recv_tok;
OM_uint32 ms;
u_char *p = NULL;
size_t len;
int r;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
gssctxt = authctxt->methoddata;
if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
free(p);
return r;
}
/* Stick it into GSSAPI and see what it says */
recv_tok.value = p;
recv_tok.length = len;
(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
&recv_tok, &send_tok, NULL);
free(p);
gss_release_buffer(&ms, &send_tok);
/* Server will be returning a failed packet after this one */
return 0;
}
/* ARGSUSED */
static int
input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
{
char *msg = NULL;
char *lang = NULL;
int r;
if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */
(r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */
(r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
goto out;
r = sshpkt_get_end(ssh);
debug("Server GSSAPI Error:\n%s", msg);
out:
free(msg);
free(lang);
return r;
}
#endif /* GSSAPI */
static int
userauth_none(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
int r;
/* initial userauth request */
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
return 1;
}
static int
userauth_passwd(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
char *password, *prompt = NULL;
const char *host = options.host_key_alias ? options.host_key_alias :
authctxt->host;
int r;
if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
return 0;
if (authctxt->attempt_passwd != 1)
error("Permission denied, please try again.");
xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
password = read_passphrase(prompt, 0);
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_u8(ssh, 0)) != 0 ||
(r = sshpkt_put_cstring(ssh, password)) != 0 ||
(r = sshpkt_add_padding(ssh, 64)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
free(prompt);
if (password != NULL)
freezero(password, strlen(password));
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
return 1;
}
/*
* parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
*/
/* ARGSUSED */
static int
input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
char prompt[256];
const char *host;
int r;
debug2("input_userauth_passwd_changereq");
if (authctxt == NULL)
fatal("input_userauth_passwd_changereq: "
"no authentication context");
host = options.host_key_alias ? options.host_key_alias : authctxt->host;
if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
goto out;
if (strlen(info) > 0)
logit("%s", info);
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */
goto out;
snprintf(prompt, sizeof(prompt),
"Enter %.30s@%.128s's old password: ",
authctxt->server_user, host);
password = read_passphrase(prompt, 0);
if ((r = sshpkt_put_cstring(ssh, password)) != 0)
goto out;
freezero(password, strlen(password));
password = NULL;
while (password == NULL) {
snprintf(prompt, sizeof(prompt),
"Enter %.30s@%.128s's new password: ",
authctxt->server_user, host);
password = read_passphrase(prompt, RP_ALLOW_EOF);
if (password == NULL) {
/* bail out */
r = 0;
goto out;
}
snprintf(prompt, sizeof(prompt),
"Retype %.30s@%.128s's new password: ",
authctxt->server_user, host);
retype = read_passphrase(prompt, 0);
if (strcmp(password, retype) != 0) {
freezero(password, strlen(password));
logit("Mismatch; try again, EOF to quit.");
password = NULL;
}
freezero(retype, strlen(retype));
}
if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
(r = sshpkt_add_padding(ssh, 64)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
r = 0;
out:
if (password)
freezero(password, strlen(password));
free(info);
free(lang);
return r;
}
/*
* Select an algorithm for publickey signatures.
* Returns algorithm (caller must free) or NULL if no mutual algorithm found.
*
* Call with ssh==NULL to ignore server-sig-algs extension list and
* only attempt with the key's base signature type.
*/
static char *
key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
{
char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
const char *server_sig_algs;
/*
* The signature algorithm will only differ from the key algorithm
* for RSA keys/certs and when the server advertises support for
* newer (SHA2) algorithms.
*/
if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
(key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
(key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) {
/* Filter base key signature alg against our configuration */
return match_list(sshkey_ssh_name(key),
options.pubkey_accepted_algos, NULL);
}
/*
* Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but
* fails to advertise it via SSH2_MSG_EXT_INFO.
*/
server_sig_algs = ssh->kex->server_sig_algs;
if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74))
server_sig_algs = "rsa-sha2-256,rsa-sha2-512";
/*
* For RSA keys/certs, since these might have a different sig type:
* find the first entry in PubkeyAcceptedAlgorithms of the right type
* that also appears in the supported signature algorithms list from
* the server.
*/
oallowed = allowed = xstrdup(options.pubkey_accepted_algos);
while ((cp = strsep(&allowed, ",")) != NULL) {
if (sshkey_type_from_name(cp) != key->type)
continue;
tmp = match_list(sshkey_sigalg_by_name(cp),
server_sig_algs, NULL);
if (tmp != NULL)
alg = xstrdup(cp);
free(tmp);
if (alg != NULL)
break;
}
free(oallowed);
return alg;
}
static int
identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, u_int compat, const char *alg)
{
struct sshkey *sign_key = NULL, *prv = NULL;
int retried = 0, r = SSH_ERR_INTERNAL_ERROR;
struct notifier_ctx *notifier = NULL;
char *fp = NULL, *pin = NULL, *prompt = NULL;
*sigp = NULL;
*lenp = 0;
/* The agent supports this key. */
if (id->key != NULL && id->agent_fd != -1) {
return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
data, datalen, alg, compat);
}
/*
* We have already loaded the private key or the private key is
* stored in external hardware.
*/
if (id->key != NULL &&
(id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
sign_key = id->key;
} else {
/* Load the private key from the file. */
if ((prv = load_identity_file(id)) == NULL)
return SSH_ERR_KEY_NOT_FOUND;
if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
error_f("private key %s contents do not match public",
id->filename);
r = SSH_ERR_KEY_NOT_FOUND;
goto out;
}
sign_key = prv;
if (sshkey_is_sk(sign_key)) {
if ((sign_key->sk_flags &
SSH_SK_USER_VERIFICATION_REQD)) {
retry_pin:
xasprintf(&prompt, "Enter PIN for %s key %s: ",
sshkey_type(sign_key), id->filename);
pin = read_passphrase(prompt, 0);
}
if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
/* XXX should batch mode just skip these? */
if ((fp = sshkey_fingerprint(sign_key,
options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
fatal_f("fingerprint failed");
notifier = notify_start(options.batch_mode,
"Confirm user presence for key %s %s",
sshkey_type(sign_key), fp);
free(fp);
}
}
}
if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
alg, options.sk_provider, pin, compat)) != 0) {
debug_fr(r, "sshkey_sign");
if (pin == NULL && !retried && sshkey_is_sk(sign_key) &&
r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
notify_complete(notifier, NULL);
notifier = NULL;
retried = 1;
goto retry_pin;
}
goto out;
}
/*
* PKCS#11 tokens may not support all signature algorithms,
* so check what we get back.
*/
if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
debug_fr(r, "sshkey_check_sigtype");
goto out;
}
/* success */
r = 0;
out:
free(prompt);
if (pin != NULL)
freezero(pin, strlen(pin));
notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL);
sshkey_free(prv);
return r;
}
static int
id_filename_matches(Identity *id, Identity *private_id)
{
const char *suffixes[] = { ".pub", "-cert.pub", NULL };
size_t len = strlen(id->filename), plen = strlen(private_id->filename);
size_t i, slen;
if (strcmp(id->filename, private_id->filename) == 0)
return 1;
for (i = 0; suffixes[i]; i++) {
slen = strlen(suffixes[i]);
if (len > slen && plen == len - slen &&
strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
memcmp(id->filename, private_id->filename, plen) == 0)
return 1;
}
return 0;
}
static int
sign_and_send_pubkey(struct ssh *ssh, Identity *id)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
struct sshbuf *b = NULL;
Identity *private_id, *sign_id = NULL;
u_char *signature = NULL;
size_t slen = 0, skip = 0;
int r, fallback_sigtype, sent = 0;
char *alg = NULL, *fp = NULL;
const char *loc = "";
if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
return 0;
debug3_f("%s %s", sshkey_type(id->key), fp);
/*
* If the key is an certificate, try to find a matching private key
* and use it to complete the signature.
* If no such private key exists, fall back to trying the certificate
* key itself in case it has a private half already loaded.
* This will try to set sign_id to the private key that will perform
* the signature.
*/
if (sshkey_is_cert(id->key)) {
TAILQ_FOREACH(private_id, &authctxt->keys, next) {
if (sshkey_equal_public(id->key, private_id->key) &&
id->key->type != private_id->key->type) {
sign_id = private_id;
break;
}
}
/*
* Exact key matches are preferred, but also allow
* filename matches for non-PKCS#11/agent keys that
* didn't load public keys. This supports the case
* of keeping just a private key file and public
* certificate on disk.
*/
if (sign_id == NULL &&
!id->isprivate && id->agent_fd == -1 &&
(id->key->flags & SSHKEY_FLAG_EXT) == 0) {
TAILQ_FOREACH(private_id, &authctxt->keys, next) {
if (private_id->key == NULL &&
id_filename_matches(id, private_id)) {
sign_id = private_id;
break;
}
}
}
if (sign_id != NULL) {
debug2_f("using private key \"%s\"%s for "
"certificate", id->filename,
id->agent_fd != -1 ? " from agent" : "");
} else {
debug_f("no separate private key for certificate "
"\"%s\"", id->filename);
}
}
/*
* If the above didn't select another identity to do the signing
* then default to the one we started with.
*/
if (sign_id == NULL)
sign_id = id;
/* assemble and sign data */
for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
free(alg);
slen = 0;
signature = NULL;
if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
id->key)) == NULL) {
error_f("no mutual signature supported");
goto out;
}
debug3_f("signing using %s %s", alg, fp);
sshbuf_free(b);
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
if (ssh->compat & SSH_OLD_SESSIONID) {
if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0)
fatal_fr(r, "sshbuf_putb");
} else {
if ((r = sshbuf_put_stringb(b,
ssh->kex->session_id)) != 0)
fatal_fr(r, "sshbuf_put_stringb");
}
skip = sshbuf_len(b);
if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
(r = sshbuf_put_u8(b, 1)) != 0 ||
(r = sshbuf_put_cstring(b, alg)) != 0 ||
(r = sshkey_puts(id->key, b)) != 0) {
fatal_fr(r, "assemble signed data");
}
/* generate signature */
r = identity_sign(sign_id, &signature, &slen,
sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg);
if (r == 0)
break;
else if (r == SSH_ERR_KEY_NOT_FOUND)
goto out; /* soft failure */
else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
!fallback_sigtype) {
if (sign_id->agent_fd != -1)
loc = "agent ";
else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
loc = "token ";
logit("%skey %s %s returned incorrect signature type",
loc, sshkey_type(id->key), fp);
continue;
}
error_fr(r, "signing failed for %s \"%s\"%s",
sshkey_type(sign_id->key), sign_id->filename,
id->agent_fd != -1 ? " from agent" : "");
goto out;
}
if (slen == 0 || signature == NULL) /* shouldn't happen */
fatal_f("no signature");
/* append signature */
if ((r = sshbuf_put_string(b, signature, slen)) != 0)
fatal_fr(r, "append signature");
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
/* skip session id and packet type */
if ((r = sshbuf_consume(b, skip + 1)) != 0)
fatal_fr(r, "consume");
/* put remaining data from buffer into packet */
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_putb(ssh, b)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "enqueue request");
/* success */
sent = 1;
out:
free(fp);
free(alg);
sshbuf_free(b);
freezero(signature, slen);
return sent;
}
static int
send_pubkey_test(struct ssh *ssh, Identity *id)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
u_char *blob = NULL;
char *alg = NULL;
size_t bloblen;
u_int have_sig = 0;
int sent = 0, r;
if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
debug_f("no mutual signature algorithm");
goto out;
}
if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
/* we cannot handle this key */
debug3_f("cannot handle key");
goto out;
}
/* register callback for USERAUTH_PK_OK message */
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
(r = sshpkt_put_cstring(ssh, alg)) != 0 ||
(r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
sent = 1;
out:
free(alg);
free(blob);
return sent;
}
static struct sshkey *
load_identity_file(Identity *id)
{
struct sshkey *private = NULL;
char prompt[300], *passphrase, *comment;
int r, quit = 0, i;
struct stat st;
if (stat(id->filename, &st) == -1) {
do_log2(id->userprovided ?
SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3,
"no such identity: %s: %s", id->filename, strerror(errno));
return NULL;
}
snprintf(prompt, sizeof prompt,
"Enter passphrase for key '%.100s': ", id->filename);
for (i = 0; i <= options.number_of_password_prompts; i++) {
if (i == 0)
passphrase = "";
else {
passphrase = read_passphrase(prompt, 0);
if (*passphrase == '\0') {
debug2("no passphrase given, try next key");
free(passphrase);
break;
}
}
switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
passphrase, &private, &comment))) {
case 0:
break;
case SSH_ERR_KEY_WRONG_PASSPHRASE:
if (options.batch_mode) {
quit = 1;
break;
}
if (i != 0)
debug2("bad passphrase given, try again...");
break;
case SSH_ERR_SYSTEM_ERROR:
if (errno == ENOENT) {
debug2_r(r, "Load key \"%s\"", id->filename);
quit = 1;
break;
}
/* FALLTHROUGH */
default:
error_r(r, "Load key \"%s\"", id->filename);
quit = 1;
break;
}
if (private != NULL && sshkey_is_sk(private) &&
options.sk_provider == NULL) {
debug("key \"%s\" is an authenticator-hosted key, "
"but no provider specified", id->filename);
sshkey_free(private);
private = NULL;
quit = 1;
}
if (!quit && private != NULL && id->agent_fd == -1 &&
!(id->key && id->isprivate))
maybe_add_key_to_agent(id->filename, private, comment,
passphrase);
if (i > 0)
freezero(passphrase, strlen(passphrase));
free(comment);
if (private != NULL || quit)
break;
}
return private;
}
static int
key_type_allowed_by_config(struct sshkey *key)
{
if (match_pattern_list(sshkey_ssh_name(key),
options.pubkey_accepted_algos, 0) == 1)
return 1;
/* RSA keys/certs might be allowed by alternate signature types */
switch (key->type) {
case KEY_RSA:
if (match_pattern_list("rsa-sha2-512",
options.pubkey_accepted_algos, 0) == 1)
return 1;
if (match_pattern_list("rsa-sha2-256",
options.pubkey_accepted_algos, 0) == 1)
return 1;
break;
case KEY_RSA_CERT:
if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
options.pubkey_accepted_algos, 0) == 1)
return 1;
if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
options.pubkey_accepted_algos, 0) == 1)
return 1;
break;
}
return 0;
}
/*
* try keys in the following order:
* 1. certificates listed in the config file
* 2. other input certificates
* 3. agent keys that are found in the config file
* 4. other agent keys
* 5. keys that are only listed in the config file
*/
static void
pubkey_prepare(Authctxt *authctxt)
{
struct identity *id, *id2, *tmp;
struct idlist agent, files, *preferred;
struct sshkey *key;
int agent_fd = -1, i, r, found;
size_t j;
struct ssh_identitylist *idlist;
char *ident;
TAILQ_INIT(&agent); /* keys from the agent */
TAILQ_INIT(&files); /* keys from the config file */
preferred = &authctxt->keys;
TAILQ_INIT(preferred); /* preferred order of keys */
/* list of keys stored in the filesystem and PKCS#11 */
for (i = 0; i < options.num_identity_files; i++) {
key = options.identity_keys[i];
if (key && key->cert &&
key->cert->type != SSH2_CERT_TYPE_USER) {
debug_f("ignoring certificate %s: not a user "
"certificate", options.identity_files[i]);
continue;
}
if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
debug_f("ignoring authenticator-hosted key %s as no "
"SecurityKeyProvider has been specified",
options.identity_files[i]);
continue;
}
options.identity_keys[i] = NULL;
id = xcalloc(1, sizeof(*id));
id->agent_fd = -1;
id->key = key;
id->filename = xstrdup(options.identity_files[i]);
id->userprovided = options.identity_file_userprovided[i];
TAILQ_INSERT_TAIL(&files, id, next);
}
/* list of certificates specified by user */
for (i = 0; i < options.num_certificate_files; i++) {
key = options.certificates[i];
if (!sshkey_is_cert(key) || key->cert == NULL ||
key->cert->type != SSH2_CERT_TYPE_USER) {
debug_f("ignoring certificate %s: not a user "
"certificate", options.identity_files[i]);
continue;
}
if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
debug_f("ignoring authenticator-hosted key "
"certificate %s as no "
"SecurityKeyProvider has been specified",
options.identity_files[i]);
continue;
}
id = xcalloc(1, sizeof(*id));
id->agent_fd = -1;
id->key = key;
id->filename = xstrdup(options.certificate_files[i]);
id->userprovided = options.certificate_file_userprovided[i];
TAILQ_INSERT_TAIL(preferred, id, next);
}
/* list of keys supported by the agent */
if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
if (r != SSH_ERR_AGENT_NOT_PRESENT)
debug_fr(r, "ssh_get_authentication_socket");
} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
if (r != SSH_ERR_AGENT_NO_IDENTITIES)
debug_fr(r, "ssh_fetch_identitylist");
close(agent_fd);
} else {
for (j = 0; j < idlist->nkeys; j++) {
found = 0;
TAILQ_FOREACH(id, &files, next) {
/*
* agent keys from the config file are
* preferred
*/
if (sshkey_equal(idlist->keys[j], id->key)) {
TAILQ_REMOVE(&files, id, next);
TAILQ_INSERT_TAIL(preferred, id, next);
id->agent_fd = agent_fd;
found = 1;
break;
}
}
if (!found && !options.identities_only) {
id = xcalloc(1, sizeof(*id));
/* XXX "steals" key/comment from idlist */
id->key = idlist->keys[j];
id->filename = idlist->comments[j];
idlist->keys[j] = NULL;
idlist->comments[j] = NULL;
id->agent_fd = agent_fd;
TAILQ_INSERT_TAIL(&agent, id, next);
}
}
ssh_free_identitylist(idlist);
/* append remaining agent keys */
TAILQ_CONCAT(preferred, &agent, next);
authctxt->agent_fd = agent_fd;
}
/* Prefer PKCS11 keys that are explicitly listed */
TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
continue;
found = 0;
TAILQ_FOREACH(id2, &files, next) {
if (id2->key == NULL ||
(id2->key->flags & SSHKEY_FLAG_EXT) != 0)
continue;
if (sshkey_equal(id->key, id2->key)) {
TAILQ_REMOVE(&files, id, next);
TAILQ_INSERT_TAIL(preferred, id, next);
found = 1;
break;
}
}
/* If IdentitiesOnly set and key not found then don't use it */
if (!found && options.identities_only) {
TAILQ_REMOVE(&files, id, next);
freezero(id, sizeof(*id));
}
}
/* append remaining keys from the config file */
TAILQ_CONCAT(preferred, &files, next);
/* finally, filter by PubkeyAcceptedAlgorithms */
TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
if (id->key != NULL && !key_type_allowed_by_config(id->key)) {
debug("Skipping %s key %s - "
"corresponding algo not in PubkeyAcceptedAlgorithms",
sshkey_ssh_name(id->key), id->filename);
TAILQ_REMOVE(preferred, id, next);
sshkey_free(id->key);
free(id->filename);
memset(id, 0, sizeof(*id));
continue;
}
}
/* List the keys we plan on using */
TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
ident = format_identity(id);
debug("Will attempt key: %s", ident);
free(ident);
}
debug2_f("done");
}
static void
pubkey_cleanup(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
Identity *id;
if (authctxt->agent_fd != -1) {
ssh_close_authentication_socket(authctxt->agent_fd);
authctxt->agent_fd = -1;
}
for (id = TAILQ_FIRST(&authctxt->keys); id;
id = TAILQ_FIRST(&authctxt->keys)) {
TAILQ_REMOVE(&authctxt->keys, id, next);
sshkey_free(id->key);
free(id->filename);
free(id);
}
}
static void
pubkey_reset(Authctxt *authctxt)
{
Identity *id;
TAILQ_FOREACH(id, &authctxt->keys, next)
id->tried = 0;
}
static int
try_identity(struct ssh *ssh, Identity *id)
{
if (!id->key)
return (0);
if (sshkey_type_plain(id->key->type) == KEY_RSA &&
(ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
debug("Skipped %s key %s for RSA/MD5 server",
sshkey_type(id->key), id->filename);
return (0);
}
return 1;
}
static int
userauth_pubkey(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
Identity *id;
int sent = 0;
char *ident;
while ((id = TAILQ_FIRST(&authctxt->keys))) {
if (id->tried++)
return (0);
/* move key to the end of the queue */
TAILQ_REMOVE(&authctxt->keys, id, next);
TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
/*
* send a test message if we have the public key. for
* encrypted keys we cannot do this and have to load the
* private key instead
*/
if (id->key != NULL) {
if (try_identity(ssh, id)) {
ident = format_identity(id);
debug("Offering public key: %s", ident);
free(ident);
sent = send_pubkey_test(ssh, id);
}
} else {
debug("Trying private key: %s", id->filename);
id->key = load_identity_file(id);
if (id->key != NULL) {
if (try_identity(ssh, id)) {
id->isprivate = 1;
sent = sign_and_send_pubkey(ssh, id);
}
sshkey_free(id->key);
id->key = NULL;
id->isprivate = 0;
}
}
if (sent)
return (sent);
}
return (0);
}
/*
* Send userauth request message specifying keyboard-interactive method.
*/
static int
userauth_kbdint(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
int r;
if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
return 0;
/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
debug3("userauth_kbdint: disable: no info_req_seen");
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
return 0;
}
debug2("userauth_kbdint");
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */
(r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
options.kbd_interactive_devices : "")) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
return 1;
}
/*
* parse INFO_REQUEST, prompt user and send INFO_RESPONSE
*/
static int
input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
char *display_prompt = NULL, *response = NULL;
u_char echo = 0;
u_int num_prompts, i;
int r;
debug2_f("entering");
if (authctxt == NULL)
fatal_f("no authentication context");
authctxt->info_req_seen = 1;
if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
goto out;
if (strlen(name) > 0)
logit("%s", name);
if (strlen(inst) > 0)
logit("%s", inst);
if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
goto out;
/*
* Begin to build info response packet based on prompts requested.
* We commit to providing the correct number of responses, so if
* further on we run into a problem that prevents this, we have to
* be sure and clean this up and send a correct error response.
*/
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
(r = sshpkt_put_u32(ssh, num_prompts)) != 0)
goto out;
debug2_f("num_prompts %d", num_prompts);
for (i = 0; i < num_prompts; i++) {
if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
(r = sshpkt_get_u8(ssh, &echo)) != 0)
goto out;
if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s",
authctxt->server_user, options.host_key_alias ?
options.host_key_alias : authctxt->host, prompt) == -1)
fatal_f("asmprintf failed");
response = read_passphrase(display_prompt, echo ? RP_ECHO : 0);
if ((r = sshpkt_put_cstring(ssh, response)) != 0)
goto out;
freezero(response, strlen(response));
free(prompt);
free(display_prompt);
display_prompt = response = prompt = NULL;
}
/* done with parsing incoming message. */
if ((r = sshpkt_get_end(ssh)) != 0 ||
(r = sshpkt_add_padding(ssh, 64)) != 0)
goto out;
r = sshpkt_send(ssh);
out:
if (response)
freezero(response, strlen(response));
free(prompt);
free(display_prompt);
free(name);
free(inst);
free(lang);
return r;
}
static int
ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen)
{
struct sshbuf *b;
struct stat st;
pid_t pid;
int r, to[2], from[2], status;
int sock = ssh_packet_get_connection_in(ssh);
u_char rversion = 0, version = 2;
void (*osigchld)(int);
*sigp = NULL;
*lenp = 0;
if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
error_f("not installed: %s", strerror(errno));
return -1;
}
if (fflush(stdout) != 0) {
error_f("fflush: %s", strerror(errno));
return -1;
}
if (pipe(to) == -1) {
error_f("pipe: %s", strerror(errno));
return -1;
}
if (pipe(from) == -1) {
error_f("pipe: %s", strerror(errno));
return -1;
}
if ((pid = fork()) == -1) {
error_f("fork: %s", strerror(errno));
return -1;
}
osigchld = ssh_signal(SIGCHLD, SIG_DFL);
if (pid == 0) {
close(from[0]);
if (dup2(from[1], STDOUT_FILENO) == -1)
fatal_f("dup2: %s", strerror(errno));
close(to[1]);
if (dup2(to[0], STDIN_FILENO) == -1)
fatal_f("dup2: %s", strerror(errno));
close(from[1]);
close(to[0]);
if (dup2(sock, STDERR_FILENO + 1) == -1)
fatal_f("dup2: %s", strerror(errno));
sock = STDERR_FILENO + 1;
fcntl(sock, F_SETFD, 0); /* keep the socket on exec */
closefrom(sock + 1);
debug3_f("[child] pid=%ld, exec %s",
(long)getpid(), _PATH_SSH_KEY_SIGN);
execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN,
strerror(errno));
}
close(from[1]);
close(to[0]);
sock = STDERR_FILENO + 1;
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
/* send # of sock, data to be signed */
if ((r = sshbuf_put_u32(b, sock)) != 0 ||
(r = sshbuf_put_string(b, data, datalen)) != 0)
fatal_fr(r, "buffer error");
if (ssh_msg_send(to[1], version, b) == -1)
fatal_f("couldn't send request");
sshbuf_reset(b);
r = ssh_msg_recv(from[0], b);
close(from[0]);
close(to[1]);
if (r < 0) {
error_f("no reply");
goto fail;
}
errno = 0;
while (waitpid(pid, &status, 0) == -1) {
if (errno != EINTR) {
error_f("waitpid %ld: %s", (long)pid, strerror(errno));
goto fail;
}
}
if (!WIFEXITED(status)) {
error_f("exited abnormally");
goto fail;
}
if (WEXITSTATUS(status) != 0) {
error_f("exited with status %d", WEXITSTATUS(status));
goto fail;
}
if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
error_fr(r, "buffer error");
goto fail;
}
if (rversion != version) {
error_f("bad version");
goto fail;
}
if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
error_fr(r, "buffer error");
fail:
ssh_signal(SIGCHLD, osigchld);
sshbuf_free(b);
return -1;
}
ssh_signal(SIGCHLD, osigchld);
sshbuf_free(b);
return 0;
}
static int
userauth_hostbased(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
struct sshkey *private = NULL;
struct sshbuf *b = NULL;
u_char *sig = NULL, *keyblob = NULL;
char *fp = NULL, *chost = NULL, *lname = NULL;
size_t siglen = 0, keylen = 0;
int i, r, success = 0;
if (authctxt->ktypes == NULL) {
authctxt->oktypes = xstrdup(options.hostbased_accepted_algos);
authctxt->ktypes = authctxt->oktypes;
}
/*
* Work through each listed type pattern in HostbasedAcceptedAlgorithms,
* trying each hostkey that matches the type in turn.
*/
for (;;) {
if (authctxt->active_ktype == NULL)
authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
if (authctxt->active_ktype == NULL ||
*authctxt->active_ktype == '\0')
break;
debug3_f("trying key type %s", authctxt->active_ktype);
/* check for a useful key */
private = NULL;
for (i = 0; i < authctxt->sensitive->nkeys; i++) {
if (authctxt->sensitive->keys[i] == NULL ||
authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
continue;
if (match_pattern_list(
sshkey_ssh_name(authctxt->sensitive->keys[i]),
authctxt->active_ktype, 0) != 1)
continue;
/* we take and free the key */
private = authctxt->sensitive->keys[i];
authctxt->sensitive->keys[i] = NULL;
break;
}
/* Found one */
if (private != NULL)
break;
/* No more keys of this type; advance */
authctxt->active_ktype = NULL;
}
if (private == NULL) {
free(authctxt->oktypes);
authctxt->oktypes = authctxt->ktypes = NULL;
authctxt->active_ktype = NULL;
debug("No more client hostkeys for hostbased authentication.");
goto out;
}
if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL) {
error_f("sshkey_fingerprint failed");
goto out;
}
debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp);
/* figure out a name for the client host */
lname = get_local_name(ssh_packet_get_connection_in(ssh));
if (lname == NULL) {
error_f("cannot get local ipaddr/name");
goto out;
}
/* XXX sshbuf_put_stringf? */
xasprintf(&chost, "%s.", lname);
debug2_f("chost %s", chost);
/* construct data */
if ((b = sshbuf_new()) == NULL) {
error_f("sshbuf_new failed");
goto out;
}
if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
error_fr(r, "sshkey_to_blob");
goto out;
}
if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 ||
(r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
(r = sshbuf_put_cstring(b, chost)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
error_fr(r, "buffer error");
goto out;
}
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
if ((r = ssh_keysign(ssh, private, &sig, &siglen,
sshbuf_ptr(b), sshbuf_len(b))) != 0) {
error("sign using hostkey %s %s failed",
sshkey_ssh_name(private), fp);
goto out;
}
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 ||
(r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
(r = sshpkt_put_cstring(ssh, chost)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
(r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
error_fr(r, "packet error");
goto out;
}
success = 1;
out:
if (sig != NULL)
freezero(sig, siglen);
free(keyblob);
free(lname);
free(fp);
free(chost);
sshkey_free(private);
sshbuf_free(b);
return success;
}
/* find auth method */
/*
* given auth method name, if configurable options permit this method fill
* in auth_ident field and return true, otherwise return false.
*/
static int
authmethod_is_enabled(Authmethod *method)
{
if (method == NULL)
return 0;
/* return false if options indicate this method is disabled */
if (method->enabled == NULL || *method->enabled == 0)
return 0;
/* return false if batch mode is enabled but method needs interactive mode */
if (method->batch_flag != NULL && *method->batch_flag != 0)
return 0;
return 1;
}
static Authmethod *
authmethod_lookup(const char *name)
{
Authmethod *method = NULL;
if (name != NULL)
for (method = authmethods; method->name != NULL; method++)
if (strcmp(name, method->name) == 0)
return method;
debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
return NULL;
}
/* XXX internal state */
static Authmethod *current = NULL;
static char *supported = NULL;
static char *preferred = NULL;
/*
* Given the authentication method list sent by the server, return the
* next method we should try. If the server initially sends a nil list,
* use a built-in default list.
*/
static Authmethod *
authmethod_get(char *authlist)
{
char *name = NULL;
u_int next;
/* Use a suitable default if we're passed a nil list. */
if (authlist == NULL || strlen(authlist) == 0)
authlist = options.preferred_authentications;
if (supported == NULL || strcmp(authlist, supported) != 0) {
debug3("start over, passed a different list %s", authlist);
free(supported);
supported = xstrdup(authlist);
preferred = options.preferred_authentications;
debug3("preferred %s", preferred);
current = NULL;
} else if (current != NULL && authmethod_is_enabled(current))
return current;
for (;;) {
if ((name = match_list(preferred, supported, &next)) == NULL) {
debug("No more authentication methods to try.");
current = NULL;
return NULL;
}
preferred += next;
debug3("authmethod_lookup %s", name);
debug3("remaining preferred: %s", preferred);
if ((current = authmethod_lookup(name)) != NULL &&
authmethod_is_enabled(current)) {
debug3("authmethod_is_enabled %s", name);
debug("Next authentication method: %s", name);
free(name);
return current;
}
free(name);
}
}
static char *
authmethods_get(void)
{
Authmethod *method = NULL;
struct sshbuf *b;
char *list;
int r;
if ((b = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
for (method = authmethods; method->name != NULL; method++) {
if (authmethod_is_enabled(method)) {
if ((r = sshbuf_putf(b, "%s%s",
sshbuf_len(b) ? "," : "", method->name)) != 0)
fatal_fr(r, "buffer error");
}
}
if ((list = sshbuf_dup_string(b)) == NULL)
fatal_f("sshbuf_dup_string failed");
sshbuf_free(b);
return list;
}
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