File: [local] / src / usr.bin / ssh / sshconnect2.c (download)
Revision 1.180, Fri Feb 26 20:29:54 2010 UTC (14 years, 3 months ago) by djm
Branch: MAIN
CVS Tags: OPENBSD_4_7_BASE, OPENBSD_4_7
Changes since 1.179: +3 -1 lines
Add support for certificate key types for users and hosts.
OpenSSH certificate key types are not X.509 certificates, but a much
simpler format that encodes a public key, identity information and
some validity constraints and signs it with a CA key. CA keys are
regular SSH keys. This certificate style avoids the attack surface
of X.509 certificates and is very easy to deploy.
Certified host keys allow automatic acceptance of new host keys
when a CA certificate is marked as trusted in ~/.ssh/known_hosts.
see VERIFYING HOST KEYS in ssh(1) for details.
Certified user keys allow authentication of users when the signing
CA key is marked as trusted in authorized_keys. See "AUTHORIZED_KEYS
FILE FORMAT" in sshd(8) for details.
Certificates are minted using ssh-keygen(1), documentation is in
the "CERTIFICATES" section of that manpage.
Documentation on the format of certificates is in the file
PROTOCOL.certkeys
feedback and ok markus@
|
/* $OpenBSD: sshconnect2.c,v 1.180 2010/02/26 20:29:54 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 "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 "readconf.h"
#include "misc.h"
#include "match.h"
#include "dispatch.h"
#include "canohost.h"
#include "msg.h"
#include "pathnames.h"
#include "uidswap.h"
#include "schnorr.h"
#include "jpake.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;
Kex *xxx_kex = NULL;
static int
verify_host_key_callback(Key *hostkey)
{
if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
fatal("Host key verification failed.");
return 0;
}
void
ssh_kex2(char *host, struct sockaddr *hostaddr)
{
Kex *kex;
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] =
options.hostkeyalgorithms;
if (options.rekey_limit)
packet_set_rekey_limit((u_int32_t)options.rekey_limit);
/* start key exchange */
kex = kex_setup(myproposal);
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->client_version_string=client_version_string;
kex->server_version_string=server_version_string;
kex->verify_host_key=&verify_host_key_callback;
xxx_kex = kex;
dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
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 Authctxt Authctxt;
typedef struct Authmethod Authmethod;
typedef struct identity Identity;
typedef struct idlist Idlist;
struct identity {
TAILQ_ENTRY(identity) next;
AuthenticationConnection *ac; /* set if agent supports key */
Key *key; /* public/private key */
char *filename; /* comment for agent-only keys */
int tried;
int isprivate; /* key points to the private key */
};
TAILQ_HEAD(idlist, identity);
struct Authctxt {
const char *server_user;
const char *local_user;
const char *host;
const char *service;
Authmethod *method;
int success;
char *authlist;
/* pubkey */
Idlist keys;
AuthenticationConnection *agent;
/* hostbased */
Sensitive *sensitive;
/* kbd-interactive */
int info_req_seen;
/* generic */
void *methoddata;
};
struct Authmethod {
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 */
};
void input_userauth_success(int, u_int32_t, void *);
void input_userauth_success_unexpected(int, u_int32_t, void *);
void input_userauth_failure(int, u_int32_t, void *);
void input_userauth_banner(int, u_int32_t, void *);
void input_userauth_error(int, u_int32_t, void *);
void input_userauth_info_req(int, u_int32_t, void *);
void input_userauth_pk_ok(int, u_int32_t, void *);
void input_userauth_passwd_changereq(int, u_int32_t, void *);
void input_userauth_jpake_server_step1(int, u_int32_t, void *);
void input_userauth_jpake_server_step2(int, u_int32_t, void *);
void input_userauth_jpake_server_confirm(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 *);
int userauth_jpake(Authctxt *);
void userauth_jpake_cleanup(Authctxt *);
#ifdef GSSAPI
int userauth_gssapi(Authctxt *authctxt);
void input_gssapi_response(int type, u_int32_t, void *);
void input_gssapi_token(int type, u_int32_t, void *);
void input_gssapi_hash(int type, u_int32_t, void *);
void input_gssapi_error(int, u_int32_t, void *);
void 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 *);
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},
#ifdef JPAKE
{"jpake-01@openssh.com",
userauth_jpake,
userauth_jpake_cleanup,
&options.zero_knowledge_password_authentication,
&options.batch_mode},
#endif
{"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);
xfree(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.info_req_seen = 0;
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);
if (authctxt->methoddata) {
xfree(authctxt->methoddata);
authctxt->methoddata = NULL;
}
if (authlist == NULL) {
authlist = authctxt->authlist;
} else {
if (authctxt->authlist)
xfree(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 */
void
input_userauth_error(int type, u_int32_t seq, void *ctxt)
{
fatal("input_userauth_error: bad message during authentication: "
"type %d", type);
}
/* ARGSUSED */
void
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);
xfree(msg);
}
xfree(raw);
xfree(lang);
}
/* ARGSUSED */
void
input_userauth_success(int type, u_int32_t seq, void *ctxt)
{
Authctxt *authctxt = ctxt;
if (authctxt == NULL)
fatal("input_userauth_success: no authentication context");
if (authctxt->authlist) {
xfree(authctxt->authlist);
authctxt->authlist = NULL;
}
if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
authctxt->method->cleanup(authctxt);
if (authctxt->methoddata) {
xfree(authctxt->methoddata);
authctxt->methoddata = NULL;
}
authctxt->success = 1; /* break out */
}
void
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);
}
/* ARGSUSED */
void
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.");
debug("Authentications that can continue: %s", authlist);
userauth(authctxt, authlist);
}
/* ARGSUSED */
void
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;
}
fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
debug2("input_userauth_pk_ok: fp %s", fp);
xfree(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);
xfree(pkalg);
xfree(pkblob);
/* try another method if we did not send a packet */
if (sent == 0)
userauth(authctxt, NULL);
}
#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 */
void
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) {
xfree(oidv);
debug("Badly encoded mechanism OID received");
userauth(authctxt, NULL);
return;
}
if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
fatal("Server returned different OID than expected");
packet_check_eom();
xfree(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;
}
}
/* ARGSUSED */
void
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);
xfree(recv_tok.value);
if (GSS_ERROR(status)) {
/* Start again with the next method in the list */
userauth(authctxt, NULL);
return;
}
}
/* ARGSUSED */
void
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 status, 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 */
status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
&recv_tok, &send_tok, NULL);
xfree(recv_tok.value);
gss_release_buffer(&ms, &send_tok);
/* Server will be returning a failed packet after this one */
}
/* ARGSUSED */
void
input_gssapi_error(int type, u_int32_t plen, void *ctxt)
{
OM_uint32 maj, min;
char *msg;
char *lang;
maj=packet_get_int();
min=packet_get_int();
msg=packet_get_string(NULL);
lang=packet_get_string(NULL);
packet_check_eom();
debug("Server GSSAPI Error:\n%s", msg);
xfree(msg);
xfree(lang);
}
#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);
memset(password, 0, strlen(password));
xfree(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 */
void
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);
xfree(info);
xfree(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);
memset(password, 0, strlen(password));
xfree(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;
}
snprintf(prompt, sizeof(prompt),
"Retype %.30s@%.128s's new password: ",
authctxt->server_user, host);
retype = read_passphrase(prompt, 0);
if (strcmp(password, retype) != 0) {
memset(password, 0, strlen(password));
xfree(password);
logit("Mismatch; try again, EOF to quit.");
password = NULL;
}
memset(retype, 0, strlen(retype));
xfree(retype);
}
packet_put_cstring(password);
memset(password, 0, strlen(password));
xfree(password);
packet_add_padding(64);
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
}
#ifdef JPAKE
static char *
pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
{
/* OpenBSD crypt(3) handles all of these */
if (strcmp(crypt_scheme, "crypt") == 0 ||
strcmp(crypt_scheme, "bcrypt") == 0 ||
strcmp(crypt_scheme, "md5crypt") == 0 ||
strcmp(crypt_scheme, "crypt-extended") == 0)
return xstrdup(crypt(password, salt));
error("%s: unsupported password encryption scheme \"%.100s\"",
__func__, crypt_scheme);
return NULL;
}
static BIGNUM *
jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
const char *salt)
{
char prompt[256], *password, *crypted;
u_char *secret;
u_int secret_len;
BIGNUM *ret;
snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
authctxt->server_user, authctxt->host);
password = read_passphrase(prompt, 0);
if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
logit("Disabling %s authentication", authctxt->method->name);
authctxt->method->enabled = NULL;
/* Continue with an empty password to fail gracefully */
crypted = xstrdup("");
}
#ifdef JPAKE_DEBUG
debug3("%s: salt = %s", __func__, salt);
debug3("%s: scheme = %s", __func__, crypt_scheme);
debug3("%s: crypted = %s", __func__, crypted);
#endif
if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
&secret, &secret_len) != 0)
fatal("%s: hash_buffer", __func__);
bzero(password, strlen(password));
bzero(crypted, strlen(crypted));
xfree(password);
xfree(crypted);
if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
fatal("%s: BN_bin2bn (secret)", __func__);
bzero(secret, secret_len);
xfree(secret);
return ret;
}
/* ARGSUSED */
void
input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
{
Authctxt *authctxt = ctxt;
struct jpake_ctx *pctx = authctxt->methoddata;
u_char *x3_proof, *x4_proof, *x2_s_proof;
u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
char *crypt_scheme, *salt;
/* Disable this message */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
if ((pctx->g_x3 = BN_new()) == NULL ||
(pctx->g_x4 = BN_new()) == NULL)
fatal("%s: BN_new", __func__);
/* Fetch step 1 values */
crypt_scheme = packet_get_string(NULL);
salt = packet_get_string(NULL);
pctx->server_id = packet_get_string(&pctx->server_id_len);
packet_get_bignum2(pctx->g_x3);
packet_get_bignum2(pctx->g_x4);
x3_proof = packet_get_string(&x3_proof_len);
x4_proof = packet_get_string(&x4_proof_len);
packet_check_eom();
JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
/* Obtain password and derive secret */
pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
bzero(crypt_scheme, strlen(crypt_scheme));
bzero(salt, strlen(salt));
xfree(crypt_scheme);
xfree(salt);
JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
/* Calculate step 2 values */
jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
pctx->g_x3, pctx->g_x4, pctx->x2,
pctx->server_id, pctx->server_id_len,
pctx->client_id, pctx->client_id_len,
x3_proof, x3_proof_len,
x4_proof, x4_proof_len,
&pctx->a,
&x2_s_proof, &x2_s_proof_len);
bzero(x3_proof, x3_proof_len);
bzero(x4_proof, x4_proof_len);
xfree(x3_proof);
xfree(x4_proof);
JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
/* Send values for step 2 */
packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
packet_put_bignum2(pctx->a);
packet_put_string(x2_s_proof, x2_s_proof_len);
packet_send();
bzero(x2_s_proof, x2_s_proof_len);
xfree(x2_s_proof);
/* Expect step 2 packet from peer */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
input_userauth_jpake_server_step2);
}
/* ARGSUSED */
void
input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
{
Authctxt *authctxt = ctxt;
struct jpake_ctx *pctx = authctxt->methoddata;
u_char *x4_s_proof;
u_int x4_s_proof_len;
/* Disable this message */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
if ((pctx->b = BN_new()) == NULL)
fatal("%s: BN_new", __func__);
/* Fetch step 2 values */
packet_get_bignum2(pctx->b);
x4_s_proof = packet_get_string(&x4_s_proof_len);
packet_check_eom();
JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
/* Derive shared key and calculate confirmation hash */
jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
pctx->client_id, pctx->client_id_len,
pctx->server_id, pctx->server_id_len,
session_id2, session_id2_len,
x4_s_proof, x4_s_proof_len,
&pctx->k,
&pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
bzero(x4_s_proof, x4_s_proof_len);
xfree(x4_s_proof);
JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
/* Send key confirmation proof */
packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
packet_send();
/* Expect confirmation from peer */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
input_userauth_jpake_server_confirm);
}
/* ARGSUSED */
void
input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
{
Authctxt *authctxt = ctxt;
struct jpake_ctx *pctx = authctxt->methoddata;
/* Disable this message */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
packet_check_eom();
JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
/* Verify expected confirmation hash */
if (jpake_check_confirm(pctx->k,
pctx->server_id, pctx->server_id_len,
session_id2, session_id2_len,
pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
debug("%s: %s success", __func__, authctxt->method->name);
else {
debug("%s: confirmation mismatch", __func__);
/* XXX stash this so if auth succeeds then we can warn/kill */
}
userauth_jpake_cleanup(authctxt);
}
#endif /* JPAKE */
static int
identity_sign(Identity *id, u_char **sigp, u_int *lenp,
u_char *data, u_int datalen)
{
Key *prv;
int ret;
/* the agent supports this key */
if (id->ac)
return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
data, datalen));
/*
* we have already loaded the private key or
* the private key is stored in external hardware
*/
if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
return (key_sign(id->key, sigp, lenp, data, datalen));
/* load the private key from the file */
if ((prv = load_identity_file(id->filename)) == NULL)
return (-1);
ret = key_sign(prv, sigp, lenp, data, datalen);
key_free(prv);
return (ret);
}
static int
sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
{
Buffer b;
u_char *blob, *signature;
u_int bloblen, slen;
u_int skip = 0;
int ret = -1;
int have_sig = 1;
debug3("sign_and_send_pubkey");
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));
if (ret == -1) {
xfree(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);
}
xfree(blob);
/* append signature */
buffer_put_string(&b, signature, slen);
xfree(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);
xfree(blob);
packet_send();
return 1;
}
static Key *
load_identity_file(char *filename)
{
Key *private;
char prompt[300], *passphrase;
int perm_ok = 0, quit, i;
struct stat st;
if (stat(filename, &st) < 0) {
debug3("no such identity: %s", filename);
return NULL;
}
private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
if (!perm_ok)
return NULL;
if (private == NULL) {
if (options.batch_mode)
return NULL;
snprintf(prompt, sizeof prompt,
"Enter passphrase for key '%.100s': ", filename);
for (i = 0; i < options.number_of_password_prompts; i++) {
passphrase = read_passphrase(prompt, 0);
if (strcmp(passphrase, "") != 0) {
private = key_load_private_type(KEY_UNSPEC,
filename, passphrase, NULL, NULL);
quit = 0;
} else {
debug2("no passphrase given, try next key");
quit = 1;
}
memset(passphrase, 0, strlen(passphrase));
xfree(passphrase);
if (private != NULL || quit)
break;
debug2("bad passphrase given, try again...");
}
}
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)
{
Identity *id;
Idlist agent, files, *preferred;
Key *key;
AuthenticationConnection *ac;
char *comment;
int i, found;
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 */
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]);
TAILQ_INSERT_TAIL(&files, id, next);
}
/* list of keys supported by the agent */
if ((ac = ssh_get_authentication_connection())) {
for (key = ssh_get_first_identity(ac, &comment, 2);
key != NULL;
key = ssh_get_next_identity(ac, &comment, 2)) {
found = 0;
TAILQ_FOREACH(id, &files, next) {
/* agent keys from the config file are preferred */
if (key_equal(key, id->key)) {
key_free(key);
xfree(comment);
TAILQ_REMOVE(&files, id, next);
TAILQ_INSERT_TAIL(preferred, id, next);
id->ac = ac;
found = 1;
break;
}
}
if (!found && !options.identities_only) {
id = xcalloc(1, sizeof(*id));
id->key = key;
id->filename = comment;
id->ac = ac;
TAILQ_INSERT_TAIL(&agent, id, next);
}
}
/* 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 = ac;
}
/* 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)", id->filename, id->key);
}
}
static void
pubkey_cleanup(Authctxt *authctxt)
{
Identity *id;
if (authctxt->agent != NULL)
ssh_close_authentication_connection(authctxt->agent);
for (id = TAILQ_FIRST(&authctxt->keys); id;
id = TAILQ_FIRST(&authctxt->keys)) {
TAILQ_REMOVE(&authctxt->keys, id, next);
if (id->key)
key_free(id->key);
if (id->filename)
xfree(id->filename);
xfree(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 && id->key->type != KEY_RSA1) {
debug("Offering public key: %s", id->filename);
sent = send_pubkey_test(authctxt, id);
} else if (id->key == NULL) {
debug("Trying private key: %s", id->filename);
id->key = load_identity_file(id->filename);
if (id->key != NULL) {
id->isprivate = 1;
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
*/
void
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);
xfree(name);
xfree(inst);
xfree(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);
memset(response, 0, strlen(response));
xfree(response);
xfree(prompt);
}
packet_check_eom(); /* done with parsing incoming message. */
packet_add_padding(64);
packet_send();
}
static int
ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
u_char *data, u_int datalen)
{
Buffer b;
struct stat st;
pid_t pid;
int to[2], from[2], status, version = 2;
debug2("ssh_keysign called");
if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
error("ssh_keysign: not installed: %s", strerror(errno));
return -1;
}
if (fflush(stdout) != 0)
error("ssh_keysign: fflush: %s", strerror(errno));
if (pipe(to) < 0) {
error("ssh_keysign: pipe: %s", strerror(errno));
return -1;
}
if (pipe(from) < 0) {
error("ssh_keysign: pipe: %s", strerror(errno));
return -1;
}
if ((pid = fork()) < 0) {
error("ssh_keysign: fork: %s", strerror(errno));
return -1;
}
if (pid == 0) {
/* keep the socket on exec */
fcntl(packet_get_connection_in(), F_SETFD, 0);
permanently_drop_suid(getuid());
close(from[0]);
if (dup2(from[1], STDOUT_FILENO) < 0)
fatal("ssh_keysign: dup2: %s", strerror(errno));
close(to[1]);
if (dup2(to[0], STDIN_FILENO) < 0)
fatal("ssh_keysign: dup2: %s", strerror(errno));
close(from[1]);
close(to[0]);
execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
strerror(errno));
}
close(from[1]);
close(to[0]);
buffer_init(&b);
buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
buffer_put_string(&b, data, datalen);
if (ssh_msg_send(to[1], version, &b) == -1)
fatal("ssh_keysign: couldn't send request");
if (ssh_msg_recv(from[0], &b) < 0) {
error("ssh_keysign: no reply");
buffer_free(&b);
return -1;
}
close(from[0]);
close(to[1]);
while (waitpid(pid, &status, 0) < 0)
if (errno != EINTR)
break;
if (buffer_get_char(&b) != version) {
error("ssh_keysign: bad version");
buffer_free(&b);
return -1;
}
*sigp = buffer_get_string(&b, lenp);
buffer_free(&b);
return 0;
}
int
userauth_hostbased(Authctxt *authctxt)
{
Key *private = NULL;
Sensitive *sensitive = authctxt->sensitive;
Buffer b;
u_char *signature, *blob;
char *chost, *pkalg, *p;
const char *service;
u_int blen, slen;
int ok, i, found = 0;
/* check for a useful key */
for (i = 0; i < sensitive->nkeys; i++) {
private = sensitive->keys[i];
if (private && private->type != KEY_RSA1) {
found = 1;
/* we take and free the key */
sensitive->keys[i] = NULL;
break;
}
}
if (!found) {
debug("No more client hostkeys for hostbased authentication.");
return 0;
}
if (key_to_blob(private, &blob, &blen) == 0) {
key_free(private);
return 0;
}
/* figure out a name for the client host */
p = get_local_name(packet_get_connection_in());
if (p == NULL) {
error("userauth_hostbased: cannot get local ipaddr/name");
key_free(private);
xfree(blob);
return 0;
}
xasprintf(&chost, "%s.", p);
debug2("userauth_hostbased: chost %s", chost);
xfree(p);
service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
authctxt->service;
pkalg = xstrdup(key_ssh_name(private));
buffer_init(&b);
/* construct data */
buffer_put_string(&b, session_id2, session_id2_len);
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->server_user);
buffer_put_cstring(&b, service);
buffer_put_cstring(&b, authctxt->method->name);
buffer_put_cstring(&b, pkalg);
buffer_put_string(&b, blob, blen);
buffer_put_cstring(&b, chost);
buffer_put_cstring(&b, authctxt->local_user);
#ifdef DEBUG_PK
buffer_dump(&b);
#endif
if (sensitive->external_keysign)
ok = ssh_keysign(private, &signature, &slen,
buffer_ptr(&b), buffer_len(&b));
else
ok = key_sign(private, &signature, &slen,
buffer_ptr(&b), buffer_len(&b));
key_free(private);
buffer_free(&b);
if (ok != 0) {
error("key_sign failed");
xfree(chost);
xfree(pkalg);
xfree(blob);
return 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_cstring(pkalg);
packet_put_string(blob, blen);
packet_put_cstring(chost);
packet_put_cstring(authctxt->local_user);
packet_put_string(signature, slen);
memset(signature, 's', slen);
xfree(signature);
xfree(chost);
xfree(pkalg);
xfree(blob);
packet_send();
return 1;
}
#ifdef JPAKE
int
userauth_jpake(Authctxt *authctxt)
{
struct jpake_ctx *pctx;
u_char *x1_proof, *x2_proof;
u_int x1_proof_len, x2_proof_len;
static int attempt = 0; /* XXX share with userauth_password's? */
if (attempt++ >= options.number_of_password_prompts)
return 0;
if (attempt != 1)
error("Permission denied, please try again.");
if (authctxt->methoddata != NULL)
fatal("%s: authctxt->methoddata already set (%p)",
__func__, authctxt->methoddata);
authctxt->methoddata = pctx = jpake_new();
/*
* Send request immediately, to get the protocol going while
* we do the initial computations.
*/
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();
packet_write_wait();
jpake_step1(pctx->grp,
&pctx->client_id, &pctx->client_id_len,
&pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
&x1_proof, &x1_proof_len,
&x2_proof, &x2_proof_len);
JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
packet_put_string(pctx->client_id, pctx->client_id_len);
packet_put_bignum2(pctx->g_x1);
packet_put_bignum2(pctx->g_x2);
packet_put_string(x1_proof, x1_proof_len);
packet_put_string(x2_proof, x2_proof_len);
packet_send();
bzero(x1_proof, x1_proof_len);
bzero(x2_proof, x2_proof_len);
xfree(x1_proof);
xfree(x2_proof);
/* Expect step 1 packet from peer */
dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
input_userauth_jpake_server_step1);
dispatch_set(SSH2_MSG_USERAUTH_SUCCESS,
&input_userauth_success_unexpected);
return 1;
}
void
userauth_jpake_cleanup(Authctxt *authctxt)
{
debug3("%s: clean up", __func__);
if (authctxt->methoddata != NULL) {
jpake_free(authctxt->methoddata);
authctxt->methoddata = NULL;
}
dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
}
#endif /* JPAKE */
/* 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);
if (supported != NULL)
xfree(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);
return current;
}
}
}
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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