RepoMirrors
/
openssh
mirror of git://anongit.mindrot.org/openssh.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
openssh/sshconnect2.c

1322 lines
34 KiB
C
Raw Blame History

/*
* Copyright (c) 2000 Markus Friedl. 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"
RCSID("$OpenBSD: sshconnect2.c,v 1.120 2003/06/24 08:23:46 markus Exp $");
#ifdef KRB5
#include <krb5.h>
#ifndef HEIMDAL
#define krb5_get_err_text(context,code) error_message(code)
#endif /* !HEIMDAL */
#endif
#include "openbsd-compat/sys-queue.h"
#include "ssh.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "buffer.h"
#include "packet.h"
#include "compat.h"
#include "bufaux.h"
#include "cipher.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 "readpass.h"
#include "match.h"
#include "dispatch.h"
#include "canohost.h"
#include "msg.h"
#include "pathnames.h"
/* 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,none";
} else {
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,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(options.rekey_limit);
/* start key exchange */
kex = kex_setup(myproposal);
kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
kex->kex[KEX_DH_GEX_SHA1] = 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);
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;
};
struct Authmethod {
char *name; /* string to compare against server's list */
int (*userauth)(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_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 *);
int userauth_none(Authctxt *);
int userauth_pubkey(Authctxt *);
int userauth_passwd(Authctxt *);
int userauth_kbdint(Authctxt *);
int userauth_hostbased(Authctxt *);
int userauth_kerberos(Authctxt *);
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[] = {
{"hostbased",
userauth_hostbased,
&options.hostbased_authentication,
NULL},
#if KRB5
{"kerberos-2@ssh.com",
userauth_kerberos,
&options.kerberos_authentication,
NULL},
#endif
{"publickey",
userauth_pubkey,
&options.pubkey_authentication,
NULL},
{"keyboard-interactive",
userauth_kbdint,
&options.kbd_interactive_authentication,
&options.batch_mode},
{"password",
userauth_passwd,
&options.password_authentication,
&options.batch_mode},
{"none",
userauth_none,
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.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 (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;
}
}
}
void
input_userauth_error(int type, u_int32_t seq, void *ctxt)
{
fatal("input_userauth_error: bad message during authentication: "
"type %d", type);
}
void
input_userauth_banner(int type, u_int32_t seq, void *ctxt)
{
char *msg, *lang;
debug3("input_userauth_banner");
msg = packet_get_string(NULL);
lang = packet_get_string(NULL);
fprintf(stderr, "%s", msg);
xfree(msg);
xfree(lang);
}
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->success = 1; /* break out */
}
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);
}
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);
TAILQ_FOREACH(id, &authctxt->keys, 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);
}
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;
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, authctxt->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
*/
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];
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, authctxt->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, authctxt->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, authctxt->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);
}
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 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);
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);
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;
options.identity_keys[i] = NULL;
id = xmalloc(sizeof(*id));
memset(id, 0, 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) {
id = xmalloc(sizeof(*id));
memset(id, 0, 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);
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: no 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) {
seteuid(getuid());
setuid(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);
ssh_msg_send(to[1], version, &b);
if (ssh_msg_recv(from[0], &b) < 0) {
error("ssh_keysign: no reply");
buffer_clear(&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_clear(&b);
return -1;
}
*sigp = buffer_get_string(&b, lenp);
buffer_clear(&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, len, 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);
return 0;
}
len = strlen(p) + 2;
chost = xmalloc(len);
strlcpy(chost, p, len);
strlcat(chost, ".", len);
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);
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);
packet_send();
return 1;
}
#if KRB5
static int
ssh_krb5_helper(krb5_data *ap, krb5_context *context)
{
krb5_context xcontext = NULL; /* XXX share with ssh1 */
krb5_auth_context xauth_context = NULL;
krb5_auth_context *auth_context;
krb5_error_code problem;
const char *tkfile;
struct stat buf;
krb5_ccache ccache = NULL;
const char *remotehost;
int ret;
memset(ap, 0, sizeof(*ap));
context = &xcontext;
auth_context = &xauth_context;
problem = krb5_init_context(context);
if (problem) {
debug("Kerberos v5: krb5_init_context failed");
ret = 0;
goto out;
}
tkfile = krb5_cc_default_name(*context);
if (strncmp(tkfile, "FILE:", 5) == 0)
tkfile += 5;
if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) {
debug("Kerberos v5: could not get default ccache (permission denied).");
ret = 0;
goto out;
}
problem = krb5_cc_default(*context, &ccache);
if (problem) {
debug("Kerberos v5: krb5_cc_default failed: %s",
krb5_get_err_text(*context, problem));
ret = 0;
goto out;
}
remotehost = get_canonical_hostname(1);
problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED,
"host", remotehost, NULL, ccache, ap);
if (problem) {
debug("Kerberos v5: krb5_mk_req failed: %s",
krb5_get_err_text(*context, problem));
ret = 0;
goto out;
}
ret = 1;
out:
if (ccache != NULL)
krb5_cc_close(*context, ccache);
if (*auth_context)
krb5_auth_con_free(*context, *auth_context);
return (ret);
}
int
userauth_kerberos(Authctxt *authctxt)
{
krb5_data ap;
krb5_context *context;
int ret = 0;
if (ssh_krb5_helper(&ap, context) == 0)
goto out;
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_string(ap.data, ap.length);
packet_send();
#ifdef HEIMDAL
krb5_data_free(&ap);
#else
krb5_free_data_contents(*context, &ap);
#endif
ret = 1;
out:
if (*context)
krb5_free_context(*context);
return ret;
}
#endif
/* 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;
}
Reference in New Issue View Git Blame Copy Permalink