File: [local] / src / usr.bin / ssh / sshconnect2.c (download)
Revision 1.287, Fri Sep 14 05:26:27 2018 UTC (5 years, 8 months ago) by djm
Branch: MAIN
Changes since 1.286: +53 -26 lines
second try, deals properly with missing and private-only keys:
Use consistent format in debug log for keys readied, offered and
received during public key authentication.
This makes it a little easier to see what is going on, as each message
now contains (where available) the key filename, its type and fingerprint,
and whether the key is hosted in an agent or a token.
|
/* $OpenBSD: sshconnect2.c,v 1.287 2018/09/14 05:26:27 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <pwd.h>
#include <unistd.h>
#include <vis.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"
#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, *all_key;
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) {
all_key = sshkey_alg_list(0, 0, 1, ',');
if (kex_assemble_names(&options.hostkeyalgorithms,
KEX_DEFAULT_PK_ALG, all_key) != 0)
fatal("%s: kex_assemble_namelist", __func__);
free(all_key);
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;
kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
#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 */
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("%s: %s", __func__, ssh_err(r));
#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(struct ssh *ssh, 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)
{
struct ssh *ssh = active_state; /* XXX */
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 */
ssh_dispatch_range(ssh, 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;
u_char partial;
int r;
if (authctxt == NULL)
fatal("input_userauth_failure: no authentication context");
if ((r = sshpkt_get_cstring(ssh, &authlist, NULL)) != 0 ||
(r = sshpkt_get_u8(ssh, &partial)) != 0 ||
(r = 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(authctxt, 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;
if (id->key != NULL) {
fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
SSH_FP_DEFAULT);
}
xasprintf(&ret, "%s %s%s%s%s%s%s",
id->filename,
id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
fp ? fp : "",
id->userprovided ? " explicit" : "",
(id->key && (id->key->flags & SSHKEY_FLAG_EXT)) ? " token" : "",
id->agent_fd != -1 ? " agent" : "");
free(fp);
return ret;
}
/* 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;
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("%s: server sent unknown pkalg %s", __func__, pkalg);
goto done;
}
if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r));
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("%s: server replied with unknown key: %s %s", __func__,
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, authctxt, 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(authctxt, NULL);
return r;
}
#ifdef GSSAPI
int
userauth_gssapi(Authctxt *authctxt)
{
struct ssh *ssh = active_state; /* XXX */
Gssctxt *gssctxt = NULL;
static gss_OID_set gss_supported = NULL;
static u_int mech = 0;
OM_uint32 min;
int r, 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;
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,
(gss_supported->elements[mech].length) + 2)) != 0 ||
(r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
(r = sshpkt_put_u8(ssh,
gss_supported->elements[mech].length)) != 0 ||
(r = sshpkt_put(ssh,
gss_supported->elements[mech].elements,
gss_supported->elements[mech].length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
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);
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;
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("%s: %s", __func__, ssh_err(r));
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("%s: %s", __func__, ssh_err(r));
} else {
struct sshbuf *b;
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
ssh_gssapi_buildmic(b, authctxt->server_user,
authctxt->service, "gssapi-with-mic");
if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
fatal("%s: sshbuf_mutable_ptr failed", __func__);
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("%s: %s", __func__, ssh_err(r));
}
sshbuf_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;
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(authctxt, 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(authctxt, NULL);
goto ok;
}
ok:
r = 0;
done:
free(oidv);
return r;
}
/* ARGSUSED */
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(authctxt, NULL);
/* ok */
}
r = 0;
out:
free(p);
return r;
}
/* 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_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 */
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 */
int
userauth_none(Authctxt *authctxt)
{
struct ssh *ssh = active_state; /* XXX */
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("%s: %s", __func__, ssh_err(r));
return 1;
}
int
userauth_passwd(Authctxt *authctxt)
{
struct ssh *ssh = active_state; /* XXX */
static int attempt = 0;
char prompt[256];
char *password;
const char *host = options.host_key_alias ? options.host_key_alias :
authctxt->host;
int r;
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);
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("%s: %s", __func__, ssh_err(r));
if (password)
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 */
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;
/*
* 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)) {
/* Filter base key signature alg against our configuration */
return match_list(sshkey_ssh_name(key),
options.pubkey_key_types, NULL);
}
/*
* For RSA keys/certs, since these might have a different sig type:
* find the first entry in PubkeyAcceptedKeyTypes of the right type
* that also appears in the supported signature algorithms list from
* the server.
*/
oallowed = allowed = xstrdup(options.pubkey_key_types);
while ((cp = strsep(&allowed, ",")) != NULL) {
if (sshkey_type_from_name(cp) != key->type)
continue;
tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->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 *prv;
int r;
/* 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))) {
if ((r = sshkey_sign(id->key, sigp, lenp, data, datalen,
alg, compat)) != 0)
return r;
/*
* PKCS#11 tokens may not support all signature algorithms,
* so check what we get back.
*/
if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0)
return r;
return 0;
}
/* 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;
}
r = sshkey_sign(prv, sigp, lenp, data, datalen, alg, compat);
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, Authctxt *authctxt, Identity *id)
{
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("%s: %s %s", __func__, 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("%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);
}
}
/*
* 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("%s: no mutual signature supported", __func__);
goto out;
}
debug3("%s: signing using %s", __func__, alg);
sshbuf_free(b);
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if (datafellows & SSH_OLD_SESSIONID) {
if ((r = sshbuf_put(b, session_id2,
session_id2_len)) != 0) {
fatal("%s: sshbuf_put: %s",
__func__, ssh_err(r));
}
} else {
if ((r = sshbuf_put_string(b, session_id2,
session_id2_len)) != 0) {
fatal("%s: sshbuf_put_string: %s",
__func__, ssh_err(r));
}
}
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("%s: assemble signed data: %s",
__func__, ssh_err(r));
}
/* generate signature */
r = identity_sign(sign_id, &signature, &slen,
sshbuf_ptr(b), sshbuf_len(b), datafellows, 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("%s: signing failed: %s", __func__, ssh_err(r));
goto out;
}
if (slen == 0 || signature == NULL) /* shouldn't happen */
fatal("%s: no signature", __func__);
/* append signature */
if ((r = sshbuf_put_string(b, signature, slen)) != 0)
fatal("%s: append signature: %s", __func__, ssh_err(r));
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
/* skip session id and packet type */
if ((r = sshbuf_consume(b, skip + 1)) != 0)
fatal("%s: consume: %s", __func__, ssh_err(r));
/* 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("%s: enqueue request: %s", __func__, ssh_err(r));
/* success */
sent = 1;
out:
free(fp);
free(alg);
sshbuf_free(b);
freezero(signature, slen);
return sent;
}
static int
send_pubkey_test(struct ssh *ssh, Authctxt *authctxt, Identity *id)
{
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("%s: no mutual signature algorithm", __func__);
goto out;
}
if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
/* we cannot handle this key */
debug3("%s: cannot handle key", __func__);
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("%s: %s", __func__, ssh_err(r));
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, 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)
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_key_types, 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_key_types, 0) == 1)
return 1;
if (match_pattern_list("rsa-sha2-256",
options.pubkey_key_types, 0) == 1)
return 1;
break;
case KEY_RSA_CERT:
if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
options.pubkey_key_types, 0) == 1)
return 1;
if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
options.pubkey_key_types, 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)
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)
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);
freezero(id, sizeof(*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 && !key_type_allowed_by_config(id->key)) {
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;
}
}
/* 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("%s: done", __func__);
}
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 (sshkey_type_plain(id->key->type) == KEY_RSA &&
(datafellows & SSH_BUG_RSASIGMD5) != 0) {
debug("Skipped %s key %s for RSA/MD5 server",
sshkey_type(id->key), id->filename);
return (0);
}
return 1;
}
int
userauth_pubkey(Authctxt *authctxt)
{
struct ssh *ssh = active_state; /* XXX */
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(id)) {
ident = format_identity(id);
debug("Offering public key: %s", ident);
free(ident);
sent = send_pubkey_test(ssh, 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(ssh,
authctxt, 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.
*/
int
userauth_kbdint(Authctxt *authctxt)
{
struct ssh *ssh = active_state; /* XXX */
static int attempt = 0;
int r;
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");
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("%s: %s", __func__, ssh_err(r));
ssh_dispatch_set(ssh, 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 = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
char *response = NULL;
u_char echo = 0;
u_int num_prompts, i;
int r;
debug2("input_userauth_info_req");
if (authctxt == NULL)
fatal("input_userauth_info_req: 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("input_userauth_info_req: 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;
response = read_passphrase(prompt, echo ? RP_ECHO : 0);
if ((r = sshpkt_put_cstring(ssh, response)) != 0)
goto out;
freezero(response, strlen(response));
free(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(name);
free(inst);
free(lang);
return r;
}
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);
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; /* XXX */
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_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);
/* 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, authctxt->service)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
(r = sshbuf_put_cstring(b, sshkey_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
r = ssh_keysign(private, &sig, &siglen,
sshbuf_ptr(b), sshbuf_len(b));
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, sshkey_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)
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("%s: sshbuf_new failed", __func__);
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("%s: buffer error: %s",
__func__, ssh_err(r));
}
}
if ((list = sshbuf_dup_string(b)) == NULL)
fatal("%s: sshbuf_dup_string failed", __func__);
sshbuf_free(b);
return list;
}
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