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sshconnect2.c
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/* $OpenBSD: sshconnect2.c,v 1.372 2024/01/08 00:34:34 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 "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)
{
int r;
if ((r = sshkey_check_rsa_length(hostkey,
options.required_rsa_size)) != 0)
fatal_r(r, "Bad server host key");
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, hostname);
}
/*
* 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];
char *all_key, *hkalgs = NULL;
int r, use_known_hosts_order = 0;
xxx_host = host;
xxx_hostaddr = hostaddr;
xxx_conn_info = cinfo;
if (options.rekey_limit || options.rekey_interval)
ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
options.rekey_interval);
/*
* 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 (use_known_hosts_order)
hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo);
kex_proposal_populate_entries(ssh, myproposal,
options.kex_algorithms, options.ciphers, options.macs,
compression_alg_list(options.compression),
hkalgs ? hkalgs : options.hostkeyalgorithms);
free(hkalgs);
/* 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);
kex_proposal_free_entries(myproposal);
#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_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(struct ssh *, 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.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;
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, kex_input_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);
#ifdef GSSAPI
if (authctxt.gss_supported_mechs != NULL) {
u_int ms;
gss_release_oid_set(&ms, &authctxt.gss_supported_mechs);
authctxt.gss_supported_mechs = NULL;
}
#endif
ssh->authctxt = NULL;
ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
if (!authctxt.success)
fatal("Authentication failed.");
if (ssh_packet_connection_is_on_socket(ssh)) {
verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host,
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
authctxt.method->name);
} else {
verbose("Authenticated to %s (via proxy) using \"%s\".", host,
authctxt.method->name);
}
}
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);
/* accept EXT_INFO at any time during userauth */
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ?
&kex_input_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;
}
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;
}
}
}
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;
}
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;
}
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 */
ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error);
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
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 using \"%s\" with partial success.",
authctxt->method->name);
/* 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;
}
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;
}
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;
}
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;
}
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;
}
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;
}
static int
input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
{
char *msg = NULL;
char *lang = NULL;
int r;