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dbee4119b5
openssh/sshconnect2.c
dtucker@openbsd.org a54eb27dd6 upstream commit 
Increase the buffer sizes for user prompts to ensure that
they won't be truncated by snprintf.  Based on patch from cjwatson at
debian.org via bz#2768, ok djm@

Upstream-ID: 6ffacf1abec8f40b469de5b94bfb29997d96af3e
2017-09-04 09:38:57 +10:00

1987 lines
53 KiB
C
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/* $OpenBSD: sshconnect2.c,v 1.266 2017/08/27 00:38:41 dtucker 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 <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.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 "buffer.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
#include "key.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"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
/* import */
extern char *client_version_string;
extern char *server_version_string;
extern Options options;
/*
* SSH2 key exchange
*/
u_char *session_id2 = NULL;
u_int session_id2_len = 0;
char *xxx_host;
struct sockaddr *xxx_hostaddr;
static int
verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
{
if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
fatal("Host key verification failed.");
return 0;
}
static char *
order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
{
char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
size_t maxlen;
struct hostkeys *hostkeys;
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]);
for (i = 0; i < options.num_system_hostfiles; i++)
load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
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("%s: unknown alg %s", __func__, alg);
if (lookup_key_in_hostkeys_by_type(hostkeys,
sshkey_type_plain(ktype), NULL))
ALG_APPEND(first, alg);
else
ALG_APPEND(last, alg);
}
#undef ALG_APPEND
xasprintf(&ret, "%s%s%s", first,
(*first == '\0' || *last == '\0') ? "" : ",", last);
if (*first != '\0')
debug3("%s: prefer hostkeyalgs: %s", __func__, first);
free(first);
free(last);
free(hostname);
free(oavail);
free_hostkeys(hostkeys);
return ret;
}
void
ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
{
char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
char *s;
struct kex *kex;
int r;
xxx_host = host;
xxx_hostaddr = hostaddr;
if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
fatal("%s: kex_names_cat", __func__);
myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
compat_cipher_proposal(options.ciphers);
myproposal[PROPOSAL_ENC_ALGS_STOC] =
compat_cipher_proposal(options.ciphers);
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ?
"zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
myproposal[PROPOSAL_MAC_ALGS_CTOS] =
myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
if (options.hostkeyalgorithms != NULL) {
if (kex_assemble_names(KEX_DEFAULT_PK_ALG,
&options.hostkeyalgorithms) != 0)
fatal("%s: kex_assemble_namelist", __func__);
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(options.hostkeyalgorithms);
} else {
/* Enforce default */
options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
/* Prefer algorithms that we already have keys for */
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(
order_hostkeyalgs(host, hostaddr, port));
}
if (options.rekey_limit || options.rekey_interval)
packet_set_rekey_limits(options.rekey_limit,
options.rekey_interval);
/* start key exchange */
if ((r = kex_setup(active_state, myproposal)) != 0)
fatal("kex_setup: %s", ssh_err(r));
kex = active_state->kex;
#ifdef WITH_OPENSSL
kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
# ifdef OPENSSL_HAS_ECC
kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
# endif
#endif
kex->kex[KEX_C25519_SHA256] = kexc25519_client;
kex->client_version_string=client_version_string;
kex->server_version_string=server_version_string;
kex->verify_host_key=&verify_host_key_callback;
ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
/* remove ext-info from the KEX proposals for rekeying */
myproposal[PROPOSAL_KEX_ALGS] =
compat_kex_proposal(options.kex_algorithms);
if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
fatal("kex_prop2buf: %s", ssh_err(r));
session_id2 = kex->session_id;
session_id2_len = kex->session_id_len;
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
packet_start(SSH2_MSG_IGNORE);
packet_put_cstring("markus");
packet_send();
packet_write_wait();
#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;
int attempt;
/* pubkey */
struct idlist keys;
int agent_fd;
/* hostbased */
Sensitive *sensitive;
char *oktypes, *ktypes;
const char *active_ktype;
/* kbd-interactive */
int info_req_seen;
/* generic */
void *methoddata;
};
struct cauthmethod {
char *name; /* string to compare against server's list */
int (*userauth)(Authctxt *authctxt);
void (*cleanup)(Authctxt *authctxt);
int *enabled; /* flag in option struct that enables method */
int *batch_flag; /* flag in option struct that disables method */
};
int input_userauth_service_accept(int, u_int32_t, struct ssh *);
int input_userauth_ext_info(int, u_int32_t, struct ssh *);
int input_userauth_success(int, u_int32_t, struct ssh *);
int input_userauth_success_unexpected(int, u_int32_t, struct ssh *);
int input_userauth_failure(int, u_int32_t, struct ssh *);
int input_userauth_banner(int, u_int32_t, struct ssh *);
int input_userauth_error(int, u_int32_t, struct ssh *);
int input_userauth_info_req(int, u_int32_t, struct ssh *);
int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
int userauth_none(Authctxt *);
int userauth_pubkey(Authctxt *);
int userauth_passwd(Authctxt *);
int userauth_kbdint(Authctxt *);
int userauth_hostbased(Authctxt *);
#ifdef GSSAPI
int userauth_gssapi(Authctxt *authctxt);
int input_gssapi_response(int type, u_int32_t, struct ssh *);
int input_gssapi_token(int type, u_int32_t, struct ssh *);
int input_gssapi_hash(int type, u_int32_t, struct ssh *);
int input_gssapi_error(int, u_int32_t, struct ssh *);
int input_gssapi_errtok(int, u_int32_t, struct ssh *);
#endif
void userauth(Authctxt *, char *);
static int sign_and_send_pubkey(Authctxt *, Identity *);
static void pubkey_prepare(Authctxt *);
static void pubkey_cleanup(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,
NULL,
&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(const char *local_user, const char *server_user, char *host,
Sensitive *sensitive)
{
struct ssh *ssh = active_state;
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));
pubkey_prepare(&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.agent_fd = -1;
if (authctxt.method == NULL)
fatal("ssh_userauth2: 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("%s: %s", __func__, ssh_err(r));
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 */
ssh->authctxt = NULL;
pubkey_cleanup(&authctxt);
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 */
int
input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
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(authctxt);
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 */
int
input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
{
return kex_input_ext_info(type, seqnr, ssh);
}
void
userauth(Authctxt *authctxt, char *authlist)
{
if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
authctxt->method->cleanup(authctxt);
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 */
dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
/* and try new method */
if (method->userauth(authctxt) != 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 */
int
input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
{
fatal("input_userauth_error: bad message during authentication: "
"type %d", type);
return 0;
}
/* ARGSUSED */
int
input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
{
char *msg, *lang;
u_int len;
debug3("%s", __func__);
msg = packet_get_string(&len);
lang = packet_get_string(NULL);
if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
fmprintf(stderr, "%s", msg);
free(msg);
free(lang);
return 0;
}
/* ARGSUSED */
int
input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
if (authctxt == NULL)
fatal("input_userauth_success: no authentication context");
free(authctxt->authlist);
authctxt->authlist = NULL;
if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
authctxt->method->cleanup(authctxt);
free(authctxt->methoddata);
authctxt->methoddata = NULL;
authctxt->success = 1; /* break out */
return 0;
}
int
input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
if (authctxt == NULL)
fatal("%s: no authentication context", __func__);
fatal("Unexpected authentication success during %s.",
authctxt->method->name);
return 0;
}
/* ARGSUSED */
int
input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *authlist = NULL;
int partial;
if (authctxt == NULL)
fatal("input_userauth_failure: no authentication context");
authlist = packet_get_string(NULL);
partial = packet_get_char();
packet_check_eom();
if (partial != 0) {
verbose("Authenticated with partial success.");
/* reset state */
pubkey_reset(authctxt);
}
debug("Authentications that can continue: %s", authlist);
userauth(authctxt, authlist);
return 0;
}
/* ARGSUSED */
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;
Buffer b;
int pktype, sent = 0;
u_int alen, blen;
char *pkalg, *fp;
u_char *pkblob;
if (authctxt == NULL)
fatal("input_userauth_pk_ok: no authentication context");
if (datafellows & SSH_BUG_PKOK) {
/* this is similar to SSH_BUG_PKAUTH */
debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
pkblob = packet_get_string(&blen);
buffer_init(&b);
buffer_append(&b, pkblob, blen);
pkalg = buffer_get_string(&b, &alen);
buffer_free(&b);
} else {
pkalg = packet_get_string(&alen);
pkblob = packet_get_string(&blen);
}
packet_check_eom();
debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
debug("unknown pkalg %s", pkalg);
goto done;
}
if ((key = key_from_blob(pkblob, blen)) == NULL) {
debug("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;
}
if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
goto done;
debug2("input_userauth_pk_ok: fp %s", fp);
free(fp);
/*
* 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 (key_equal(key, id->key)) {
sent = sign_and_send_pubkey(authctxt, id);
break;
}
}
done:
if (key != NULL)
key_free(key);
free(pkalg);
free(pkblob);
/* try another method if we did not send a packet */
if (sent == 0)
userauth(authctxt, NULL);
return 0;
}
#ifdef GSSAPI
int
userauth_gssapi(Authctxt *authctxt)
{
Gssctxt *gssctxt = NULL;
static gss_OID_set gss_supported = NULL;
static u_int mech = 0;
OM_uint32 min;
int ok = 0;
/* Try one GSSAPI method at a time, rather than sending them all at
* once. */
if (gss_supported == NULL)
gss_indicate_mechs(&min, &gss_supported);
/* Check to see if the mechanism is usable before we offer it */
while (mech < gss_supported->count && !ok) {
/* My DER encoding requires length<128 */
if (gss_supported->elements[mech].length < 128 &&
ssh_gssapi_check_mechanism(&gssctxt,
&gss_supported->elements[mech], authctxt->host)) {
ok = 1; /* Mechanism works */
} else {
mech++;
}
}
if (!ok)
return 0;
authctxt->methoddata=(void *)gssctxt;
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_int(1);
packet_put_int((gss_supported->elements[mech].length) + 2);
packet_put_char(SSH_GSS_OIDTYPE);
packet_put_char(gss_supported->elements[mech].length);
packet_put_raw(gss_supported->elements[mech].elements,
gss_supported->elements[mech].length);
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
mech++; /* Move along to next candidate */
return 1;
}
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;
Buffer b;
status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
recv_tok, &send_tok, &flags);
if (send_tok.length > 0) {
if (GSS_ERROR(status))
packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
else
packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
packet_put_string(send_tok.value, send_tok.length);
packet_send();
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)) {
packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
packet_send();
} else {
ssh_gssapi_buildmic(&b, authctxt->server_user,
authctxt->service, "gssapi-with-mic");
gssbuf.value = buffer_ptr(&b);
gssbuf.length = buffer_len(&b);
status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
if (!GSS_ERROR(status)) {
packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
packet_put_string(mic.value, mic.length);
packet_send();
}
buffer_free(&b);
gss_release_buffer(&ms, &mic);
}
}
return status;
}
/* ARGSUSED */
int
input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
Gssctxt *gssctxt;
int oidlen;
char *oidv;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
gssctxt = authctxt->methoddata;
/* Setup our OID */
oidv = packet_get_string(&oidlen);
if (oidlen <= 2 ||
oidv[0] != SSH_GSS_OIDTYPE ||
oidv[1] != oidlen - 2) {
free(oidv);
debug("Badly encoded mechanism OID received");
userauth(authctxt, NULL);
return 0;
}
if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
fatal("Server returned different OID than expected");
packet_check_eom();
free(oidv);
if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
/* Start again with next method on list */
debug("Trying to start again");
userauth(authctxt, NULL);
return 0;
}
return 0;
}
/* ARGSUSED */
int
input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
gss_buffer_desc recv_tok;
OM_uint32 status;
u_int slen;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
recv_tok.value = packet_get_string(&slen);
recv_tok.length = slen; /* safe typecast */
packet_check_eom();
status = process_gssapi_token(ssh, &recv_tok);
free(recv_tok.value);
if (GSS_ERROR(status)) {
/* Start again with the next method in the list */
userauth(authctxt, NULL);
return 0;
}
return 0;
}
/* ARGSUSED */
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_int len;
if (authctxt == NULL)
fatal("input_gssapi_response: no authentication context");
gssctxt = authctxt->methoddata;
recv_tok.value = packet_get_string(&len);
recv_tok.length = len;
packet_check_eom();
/* Stick it into GSSAPI and see what it says */
(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
&recv_tok, &send_tok, NULL);
free(recv_tok.value);
gss_release_buffer(&ms, &send_tok);
/* Server will be returning a failed packet after this one */
return 0;
}
/* ARGSUSED */
int
input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
{
char *msg;
char *lang;
/* maj */(void)packet_get_int();
/* min */(void)packet_get_int();
msg=packet_get_string(NULL);
lang=packet_get_string(NULL);
packet_check_eom();
debug("Server GSSAPI Error:\n%s", msg);
free(msg);
free(lang);
return 0;
}
#endif /* GSSAPI */
int
userauth_none(Authctxt *authctxt)
{
/* initial userauth request */
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_send();
return 1;
}
int
userauth_passwd(Authctxt *authctxt)
{
static int attempt = 0;
char prompt[256];
char *password;
const char *host = options.host_key_alias ? options.host_key_alias :
authctxt->host;
if (attempt++ >= options.number_of_password_prompts)
return 0;
if (attempt != 1)
error("Permission denied, please try again.");
snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
authctxt->server_user, host);
password = read_passphrase(prompt, 0);
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_char(0);
packet_put_cstring(password);
explicit_bzero(password, strlen(password));
free(password);
packet_add_padding(64);
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
return 1;
}
/*
* parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
*/
/* ARGSUSED */
int
input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *info, *lang, *password = NULL, *retype = NULL;
char prompt[256];
const char *host;
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;
info = packet_get_string(NULL);
lang = packet_get_string(NULL);
if (strlen(info) > 0)
logit("%s", info);
free(info);
free(lang);
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_char(1); /* additional info */
snprintf(prompt, sizeof(prompt),
"Enter %.30s@%.128s's old password: ",
authctxt->server_user, host);
password = read_passphrase(prompt, 0);
packet_put_cstring(password);
explicit_bzero(password, strlen(password));
free(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 */
return 0;
}
snprintf(prompt, sizeof(prompt),
"Retype %.30s@%.128s's new password: ",
authctxt->server_user, host);
retype = read_passphrase(prompt, 0);
if (strcmp(password, retype) != 0) {
explicit_bzero(password, strlen(password));
free(password);
logit("Mismatch; try again, EOF to quit.");
password = NULL;
}
explicit_bzero(retype, strlen(retype));
free(retype);
}
packet_put_cstring(password);
explicit_bzero(password, strlen(password));
free(password);
packet_add_padding(64);
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
return 0;
}
static const char *
key_sign_encode(const struct sshkey *key)
{
struct ssh *ssh = active_state;
if (key->type == KEY_RSA) {
switch (ssh->kex->rsa_sha2) {
case 256:
return "rsa-sha2-256";
case 512:
return "rsa-sha2-512";
}
}
return key_ssh_name(key);
}
static int
identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, u_int compat)
{
struct sshkey *prv;
int ret;
/* 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, key_sign_encode(id->key), 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)))
return (sshkey_sign(id->key, sigp, lenp, data, datalen,
key_sign_encode(id->key), compat));
/* 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("%s: private key %s contents do not match public",
__func__, id->filename);
return SSH_ERR_KEY_NOT_FOUND;
}
ret = sshkey_sign(prv, sigp, lenp, data, datalen,
key_sign_encode(prv), compat);
sshkey_free(prv);
return (ret);
}
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(Authctxt *authctxt, Identity *id)
{
Buffer b;
Identity *private_id;
u_char *blob, *signature;
size_t slen;
u_int bloblen, skip = 0;
int matched, ret = -1, have_sig = 1;
char *fp;
if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
return 0;
debug3("%s: %s %s", __func__, key_type(id->key), fp);
free(fp);
if (key_to_blob(id->key, &blob, &bloblen) == 0) {
/* we cannot handle this key */
debug3("sign_and_send_pubkey: cannot handle key");
return 0;
}
/* data to be signed */
buffer_init(&b);
if (datafellows & SSH_OLD_SESSIONID) {
buffer_append(&b, session_id2, session_id2_len);
skip = session_id2_len;
} else {
buffer_put_string(&b, session_id2, session_id2_len);
skip = buffer_len(&b);
}
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->server_user);
buffer_put_cstring(&b,
datafellows & SSH_BUG_PKSERVICE ?
"ssh-userauth" :
authctxt->service);
if (datafellows & SSH_BUG_PKAUTH) {
buffer_put_char(&b, have_sig);
} else {
buffer_put_cstring(&b, authctxt->method->name);
buffer_put_char(&b, have_sig);
buffer_put_cstring(&b, key_sign_encode(id->key));
}
buffer_put_string(&b, blob, bloblen);
/*
* 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.
*/
if (key_is_cert(id->key)) {
matched = 0;
TAILQ_FOREACH(private_id, &authctxt->keys, next) {
if (sshkey_equal_public(id->key, private_id->key) &&
id->key->type != private_id->key->type) {
id = private_id;
matched = 1;
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 (!matched && !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)) {
id = private_id;
matched = 1;
break;
}
}
}
if (matched) {
debug2("%s: using private key \"%s\"%s for "
"certificate", __func__, id->filename,
id->agent_fd != -1 ? " from agent" : "");
} else {
debug("%s: no separate private key for certificate "
"\"%s\"", __func__, id->filename);
}
}
/* generate signature */
ret = identity_sign(id, &signature, &slen,
buffer_ptr(&b), buffer_len(&b), datafellows);
if (ret != 0) {
if (ret != SSH_ERR_KEY_NOT_FOUND)
error("%s: signing failed: %s", __func__, ssh_err(ret));
free(blob);
buffer_free(&b);
return 0;
}
#ifdef DEBUG_PK
buffer_dump(&b);
#endif
if (datafellows & SSH_BUG_PKSERVICE) {
buffer_clear(&b);
buffer_append(&b, session_id2, session_id2_len);
skip = session_id2_len;
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->server_user);
buffer_put_cstring(&b, authctxt->service);
buffer_put_cstring(&b, authctxt->method->name);
buffer_put_char(&b, have_sig);
if (!(datafellows & SSH_BUG_PKAUTH))
buffer_put_cstring(&b, key_ssh_name(id->key));
buffer_put_string(&b, blob, bloblen);
}
free(blob);
/* append signature */
buffer_put_string(&b, signature, slen);
free(signature);
/* skip session id and packet type */
if (buffer_len(&b) < skip + 1)
fatal("userauth_pubkey: internal error");
buffer_consume(&b, skip + 1);
/* put remaining data from buffer into packet */
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_raw(buffer_ptr(&b), buffer_len(&b));
buffer_free(&b);
packet_send();
return 1;
}
static int
send_pubkey_test(Authctxt *authctxt, Identity *id)
{
u_char *blob;
u_int bloblen, have_sig = 0;
debug3("send_pubkey_test");
if (key_to_blob(id->key, &blob, &bloblen) == 0) {
/* we cannot handle this key */
debug3("send_pubkey_test: cannot handle key");
return 0;
}
/* register callback for USERAUTH_PK_OK message */
dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_char(have_sig);
if (!(datafellows & SSH_BUG_PKAUTH))
packet_put_cstring(key_sign_encode(id->key));
packet_put_string(blob, bloblen);
free(blob);
packet_send();
return 1;
}
static struct sshkey *
load_identity_file(Identity *id)
{
struct sshkey *private = NULL;
char prompt[300], *passphrase, *comment;
int r, perm_ok = 0, quit = 0, i;
struct stat st;
if (stat(id->filename, &st) < 0) {
(id->userprovided ? logit : 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, &perm_ok))) {
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("Load key \"%s\": %s",
id->filename, ssh_err(r));
quit = 1;
break;
}
/* FALLTHROUGH */
default:
error("Load key \"%s\": %s", id->filename, ssh_err(r));
quit = 1;
break;
}
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) {
explicit_bzero(passphrase, strlen(passphrase));
free(passphrase);
}
free(comment);
if (private != NULL || quit)
break;
}
return private;
}
/*
* 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;
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)
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 (!key_is_cert(key) || key->cert == NULL ||
key->cert->type != SSH2_CERT_TYPE_USER)
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("%s: ssh_get_authentication_socket: %s",
__func__, ssh_err(r));
} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
if (r != SSH_ERR_AGENT_NO_IDENTITIES)
debug("%s: ssh_fetch_identitylist: %s",
__func__, ssh_err(r));
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 */
for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
TAILQ_REMOVE(&agent, id, next);
TAILQ_INSERT_TAIL(preferred, id, 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);
explicit_bzero(id, sizeof(*id));
free(id);
}
}
/* append remaining keys from the config file */
for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
TAILQ_REMOVE(&files, id, next);
TAILQ_INSERT_TAIL(preferred, id, next);
}
/* finally, filter by PubkeyAcceptedKeyTypes */
TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
if (id->key != NULL &&
match_pattern_list(sshkey_ssh_name(id->key),
options.pubkey_key_types, 0) != 1) {
debug("Skipping %s key %s - "
"not in PubkeyAcceptedKeyTypes",
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;
}
debug2("key: %s (%p)%s%s", id->filename, id->key,
id->userprovided ? ", explicit" : "",
id->agent_fd != -1 ? ", agent" : "");
}
}
static void
pubkey_cleanup(Authctxt *authctxt)
{
Identity *id;
if (authctxt->agent_fd != -1)
ssh_close_authentication_socket(authctxt->agent_fd);
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(Identity *id)
{
if (!id->key)
return (0);
if (key_type_plain(id->key->type) == KEY_RSA &&
(datafellows & SSH_BUG_RSASIGMD5) != 0) {
debug("Skipped %s key %s for RSA/MD5 server",
key_type(id->key), id->filename);
return (0);
}
return 1;
}
int
userauth_pubkey(Authctxt *authctxt)
{
Identity *id;
int sent = 0;
char *fp;
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(id)) {
if ((fp = sshkey_fingerprint(id->key,
options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL) {
error("%s: sshkey_fingerprint failed",
__func__);
return 0;
}
debug("Offering public key: %s %s %s",
sshkey_type(id->key), fp, id->filename);
free(fp);
sent = send_pubkey_test(authctxt, id);
}
} else {
debug("Trying private key: %s", id->filename);
id->key = load_identity_file(id);
if (id->key != NULL) {
if (try_identity(id)) {
id->isprivate = 1;
sent = sign_and_send_pubkey(
authctxt, id);
}
key_free(id->key);
id->key = NULL;
id->isprivate = 0;
}
}
if (sent)
return (sent);
}
return (0);
}
/*
* Send userauth request message specifying keyboard-interactive method.
*/
int
userauth_kbdint(Authctxt *authctxt)
{
static int attempt = 0;
if (attempt++ >= options.number_of_password_prompts)
return 0;
/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
if (attempt > 1 && !authctxt->info_req_seen) {
debug3("userauth_kbdint: disable: no info_req_seen");
dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
return 0;
}
debug2("userauth_kbdint");
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_cstring(""); /* lang */
packet_put_cstring(options.kbd_interactive_devices ?
options.kbd_interactive_devices : "");
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
return 1;
}
/*
* parse INFO_REQUEST, prompt user and send INFO_RESPONSE
*/
int
input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
char *name, *inst, *lang, *prompt, *response;
u_int num_prompts, i;
int echo = 0;
debug2("input_userauth_info_req");
if (authctxt == NULL)
fatal("input_userauth_info_req: no authentication context");
authctxt->info_req_seen = 1;
name = packet_get_string(NULL);
inst = packet_get_string(NULL);
lang = packet_get_string(NULL);
if (strlen(name) > 0)
logit("%s", name);
if (strlen(inst) > 0)
logit("%s", inst);
free(name);
free(inst);
free(lang);
num_prompts = packet_get_int();
/*
* 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.
*/
packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
packet_put_int(num_prompts);
debug2("input_userauth_info_req: num_prompts %d", num_prompts);
for (i = 0; i < num_prompts; i++) {
prompt = packet_get_string(NULL);
echo = packet_get_char();
response = read_passphrase(prompt, echo ? RP_ECHO : 0);
packet_put_cstring(response);
explicit_bzero(response, strlen(response));
free(response);
free(prompt);
}
packet_check_eom(); /* done with parsing incoming message. */
packet_add_padding(64);
packet_send();
return 0;
}
static int
ssh_keysign(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 i, r, to[2], from[2], status, sock = packet_get_connection_in();
u_char rversion = 0, version = 2;
void (*osigchld)(int);
*sigp = NULL;
*lenp = 0;
if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
error("%s: not installed: %s", __func__, strerror(errno));
return -1;
}
if (fflush(stdout) != 0) {
error("%s: fflush: %s", __func__, strerror(errno));
return -1;
}
if (pipe(to) < 0) {
error("%s: pipe: %s", __func__, strerror(errno));
return -1;
}
if (pipe(from) < 0) {
error("%s: pipe: %s", __func__, strerror(errno));
return -1;
}
if ((pid = fork()) < 0) {
error("%s: fork: %s", __func__, strerror(errno));
return -1;
}
osigchld = signal(SIGCHLD, SIG_DFL);
if (pid == 0) {
/* keep the socket on exec */
fcntl(sock, F_SETFD, 0);
permanently_drop_suid(getuid());
close(from[0]);
if (dup2(from[1], STDOUT_FILENO) < 0)
fatal("%s: dup2: %s", __func__, strerror(errno));
close(to[1]);
if (dup2(to[0], STDIN_FILENO) < 0)
fatal("%s: dup2: %s", __func__, strerror(errno));
close(from[1]);
close(to[0]);
/* Close everything but stdio and the socket */
for (i = STDERR_FILENO + 1; i < sock; i++)
close(i);
closefrom(sock + 1);
debug3("%s: [child] pid=%ld, exec %s",
__func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
strerror(errno));
}
close(from[1]);
close(to[0]);
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
/* send # of sock, data to be signed */
if ((r = sshbuf_put_u32(b, sock)) != 0 ||
(r = sshbuf_put_string(b, data, datalen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (ssh_msg_send(to[1], version, b) == -1)
fatal("%s: couldn't send request", __func__);
sshbuf_reset(b);
r = ssh_msg_recv(from[0], b);
close(from[0]);
close(to[1]);
if (r < 0) {
error("%s: no reply", __func__);
goto fail;
}
errno = 0;
while (waitpid(pid, &status, 0) < 0) {
if (errno != EINTR) {
error("%s: waitpid %ld: %s",
__func__, (long)pid, strerror(errno));
goto fail;
}
}
if (!WIFEXITED(status)) {
error("%s: exited abnormally", __func__);
goto fail;
}
if (WEXITSTATUS(status) != 0) {
error("%s: exited with status %d",
__func__, WEXITSTATUS(status));
goto fail;
}
if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
error("%s: buffer error: %s", __func__, ssh_err(r));
goto fail;
}
if (rversion != version) {
error("%s: bad version", __func__);
goto fail;
}
if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
error("%s: buffer error: %s", __func__, ssh_err(r));
fail:
signal(SIGCHLD, osigchld);
sshbuf_free(b);
return -1;
}
signal(SIGCHLD, osigchld);
sshbuf_free(b);
return 0;
}
int
userauth_hostbased(Authctxt *authctxt)
{
struct ssh *ssh = active_state;
struct sshkey *private = NULL;
struct sshbuf *b = NULL;
const char *service;
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_key_types);
authctxt->ktypes = authctxt->oktypes;
}
/*
* Work through each listed type pattern in HostbasedKeyTypes,
* 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("%s: trying key type %s", __func__,
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("%s: sshkey_fingerprint failed", __func__);
goto out;
}
debug("%s: trying hostkey %s %s",
__func__, sshkey_ssh_name(private), fp);
/* figure out a name for the client host */
if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
error("%s: cannot get local ipaddr/name", __func__);
goto out;
}
/* XXX sshbuf_put_stringf? */
xasprintf(&chost, "%s.", lname);
debug2("%s: chost %s", __func__, chost);
service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
authctxt->service;
/* construct data */
if ((b = sshbuf_new()) == NULL) {
error("%s: sshbuf_new failed", __func__);
goto out;
}
if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
goto out;
}
if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 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, service)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
(r = sshbuf_put_cstring(b, key_ssh_name(private))) != 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("%s: buffer error: %s", __func__, ssh_err(r));
goto out;
}
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
if (authctxt->sensitive->external_keysign)
r = ssh_keysign(private, &sig, &siglen,
sshbuf_ptr(b), sshbuf_len(b));
else if ((r = sshkey_sign(private, &sig, &siglen,
sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
if (r != 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, key_ssh_name(private))) != 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("%s: packet error: %s", __func__, ssh_err(r));
goto out;
}
success = 1;
out:
if (sig != NULL) {
explicit_bzero(sig, siglen);
free(sig);
}
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;
Buffer b;
char *list;
buffer_init(&b);
for (method = authmethods; method->name != NULL; method++) {
if (authmethod_is_enabled(method)) {
if (buffer_len(&b) > 0)
buffer_append(&b, ",", 1);
buffer_append(&b, method->name, strlen(method->name));
}
}
if ((list = sshbuf_dup_string(&b)) == NULL)
fatal("%s: sshbuf_dup_string failed", __func__);
buffer_free(&b);
return list;
}
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