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openssh/sshconnect2.c
djm@openbsd.org 46347ed596 upstream commit 
Add a ssh_config HostbasedKeyType option to control which
 host public key types are tried during hostbased authentication.

This may be used to prevent too many keys being sent to the server,
and blowing past its MaxAuthTries limit.

bz#2211 based on patch by Iain Morgan; ok markus@
2015-01-30 22:47:01 +11:00

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/* $OpenBSD: sshconnect2.c,v 1.223 2015/01/30 11:43:14 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
* Copyright (c) 2008 Damien Miller. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <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"
#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(Key *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 };
struct kex *kex;
int r;
xxx_host = host;
xxx_hostaddr = hostaddr;
if (options.ciphers == (char *)-1) {
logit("No valid ciphers for protocol version 2 given, using defaults.");
options.ciphers = NULL;
}
if (options.ciphers != NULL) {
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
}
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
myproposal[PROPOSAL_ENC_ALGS_STOC] =
compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
if (options.compression) {
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
} else {
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
}
if (options.macs != NULL) {
myproposal[PROPOSAL_MAC_ALGS_CTOS] =
myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
}
if (options.hostkeyalgorithms != NULL)
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(options.hostkeyalgorithms);
else {
/* Prefer algorithms that we already have keys for */
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
compat_pkalg_proposal(
order_hostkeyalgs(host, hostaddr, port));
}
if (options.kex_algorithms != NULL)
myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
myproposal[PROPOSAL_KEX_ALGS]);
if (options.rekey_limit || options.rekey_interval)
packet_set_rekey_limits((u_int32_t)options.rekey_limit,
(time_t)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_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;
dispatch_run(DISPATCH_BLOCK, &kex->done, active_state);
if (options.use_roaming && !kex->roaming) {
debug("Roaming not allowed by server");
options.use_roaming = 0;
}
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_success(int, u_int32_t, void *);
int input_userauth_success_unexpected(int, u_int32_t, void *);
int input_userauth_failure(int, u_int32_t, void *);
int input_userauth_banner(int, u_int32_t, void *);
int input_userauth_error(int, u_int32_t, void *);
int input_userauth_info_req(int, u_int32_t, void *);
int input_userauth_pk_ok(int, u_int32_t, void *);
int input_userauth_passwd_changereq(int, u_int32_t, void *);
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, void *);
int input_gssapi_token(int type, u_int32_t, void *);
int input_gssapi_hash(int type, u_int32_t, void *);
int input_gssapi_error(int, u_int32_t, void *);
int input_gssapi_errtok(int, u_int32_t, void *);
#endif
void userauth(Authctxt *, char *);
static int sign_and_send_pubkey(Authctxt *, Identity *);
static void pubkey_prepare(Authctxt *);
static void pubkey_cleanup(Authctxt *);
static Key *load_identity_file(char *, int);
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)
{
Authctxt authctxt;
int type;
if (options.challenge_response_authentication)
options.kbd_interactive_authentication = 1;
packet_start(SSH2_MSG_SERVICE_REQUEST);
packet_put_cstring("ssh-userauth");
packet_send();
debug("SSH2_MSG_SERVICE_REQUEST sent");
packet_write_wait();
type = packet_read();
if (type != SSH2_MSG_SERVICE_ACCEPT)
fatal("Server denied authentication request: %d", type);
if (packet_remaining() > 0) {
char *reply = packet_get_string(NULL);
debug2("service_accept: %s", reply);
free(reply);
} else {
debug2("buggy server: service_accept w/o service");
}
packet_check_eom();
debug("SSH2_MSG_SERVICE_ACCEPT received");
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");
/* initial userauth request */
userauth_none(&authctxt);
dispatch_init(&input_userauth_error);
dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
pubkey_cleanup(&authctxt);
dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
debug("Authentication succeeded (%s).", authctxt.method->name);
}
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("Permission denied (%s).", 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, void *ctxt)
{
fatal("input_userauth_error: bad message during authentication: "
"type %d", type);
return 0;
}
/* ARGSUSED */
int
input_userauth_banner(int type, u_int32_t seq, void *ctxt)
{
char *msg, *raw, *lang;
u_int len;
debug3("input_userauth_banner");
raw = packet_get_string(&len);
lang = packet_get_string(NULL);
if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
if (len > 65536)
len = 65536;
msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
fprintf(stderr, "%s", msg);
free(msg);
}
free(raw);
free(lang);
return 0;
}
/* ARGSUSED */
int
input_userauth_success(int type, u_int32_t seq, void *ctxt)
{
Authctxt *authctxt = ctxt;
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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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) {
logit("Authenticated with partial success.");
/* reset state */
pubkey_cleanup(authctxt);
pubkey_prepare(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, void *ctxt)
{
Authctxt *authctxt = ctxt;
Key *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(void *ctxt, gss_buffer_t recv_tok)
{
Authctxt *authctxt = ctxt;
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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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(ctxt, 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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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(ctxt, &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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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, void *ctxt)
{
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[150];
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, void *ctxt)
{
Authctxt *authctxt = ctxt;
char *info, *lang, *password = NULL, *retype = NULL;
char prompt[150];
const char *host = options.host_key_alias ? options.host_key_alias :
authctxt->host;
debug2("input_userauth_passwd_changereq");
if (authctxt == NULL)
fatal("input_userauth_passwd_changereq: "
"no authentication context");
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 int
identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, u_int compat)
{
Key *prv;
int ret;
/* the agent supports this key */
if (id->agent_fd)
return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
data, datalen, compat);
/*
* we have already loaded the private key or
* the private key is stored in external hardware
*/
if (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))
return (sshkey_sign(id->key, sigp, lenp, data, datalen,
compat));
/* load the private key from the file */
if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
return (-1); /* XXX return decent error code */
ret = sshkey_sign(prv, sigp, lenp, data, datalen, compat);
sshkey_free(prv);
return (ret);
}
static int
sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
{
Buffer b;
u_char *blob, *signature;
u_int bloblen;
size_t slen;
u_int skip = 0;
int ret = -1;
int have_sig = 1;
char *fp;
if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
return 0;
debug3("sign_and_send_pubkey: %s %s", 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_ssh_name(id->key));
}
buffer_put_string(&b, blob, bloblen);
/* generate signature */
ret = identity_sign(id, &signature, &slen,
buffer_ptr(&b), buffer_len(&b), datafellows);
if (ret != 0) {
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_ssh_name(id->key));
packet_put_string(blob, bloblen);
free(blob);
packet_send();
return 1;
}
static Key *
load_identity_file(char *filename, int userprovided)
{
Key *private;
char prompt[300], *passphrase;
int r, perm_ok = 0, quit = 0, i;
struct stat st;
if (stat(filename, &st) < 0) {
(userprovided ? logit : debug3)("no such identity: %s: %s",
filename, strerror(errno));
return NULL;
}
snprintf(prompt, sizeof prompt,
"Enter passphrase for key '%.100s': ", 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, filename,
passphrase, &private, NULL, &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",
filename, ssh_err(r));
quit = 1;
break;
}
/* FALLTHROUGH */
default:
error("Load key \"%s\": %s", filename, ssh_err(r));
quit = 1;
break;
}
if (i > 0) {
explicit_bzero(passphrase, strlen(passphrase));
free(passphrase);
}
if (private != NULL || quit)
break;
}
return private;
}
/*
* try keys in the following order:
* 1. agent keys that are found in the config file
* 2. other agent keys
* 3. 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, 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->type == KEY_RSA1)
continue;
if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
continue;
options.identity_keys[i] = NULL;
id = xcalloc(1, sizeof(*id));
id->key = key;
id->filename = xstrdup(options.identity_files[i]);
id->userprovided = options.identity_file_userprovided[i];
TAILQ_INSERT_TAIL(&files, id, next);
}
/* 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);
}
}
/* 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, 2, &idlist)) != 0) {
if (r != SSH_ERR_AGENT_NO_IDENTITIES)
debug("%s: ssh_fetch_identitylist: %s",
__func__, ssh_err(r));
} 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;
}
/* 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);
}
TAILQ_FOREACH(id, preferred, next) {
debug2("key: %s (%p),%s", id->filename, id->key,
id->userprovided ? " explicit" : "");
}
}
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);
if (id->key)
sshkey_free(id->key);
free(id->filename);
free(id);
}
}
int
userauth_pubkey(Authctxt *authctxt)
{
Identity *id;
int sent = 0;
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 (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);
} else if (id->key->type != KEY_RSA1) {
debug("Offering %s public key: %s",
key_type(id->key), id->filename);
sent = send_pubkey_test(authctxt, id);
}
} else {
debug("Trying private key: %s", id->filename);
id->key = load_identity_file(id->filename,
id->userprovided);
if (id->key != NULL) {
id->isprivate = 1;
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);
} else {
sent = sign_and_send_pubkey(
authctxt, id);
}
key_free(id->key);
id->key = NULL;
}
}
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, void *ctxt)
{
Authctxt *authctxt = ctxt;
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 *) 0);
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_RSA1 ||
authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
continue;
if (match_pattern_list(
sshkey_ssh_name(authctxt->sensitive->keys[i]),
authctxt->active_ktype,
strlen(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), 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));
}
}
buffer_append(&b, "\0", 1);
list = xstrdup(buffer_ptr(&b));
buffer_free(&b);
return list;
}
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