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openssh-portable/ssh-agent.c

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/* $OpenBSD: ssh-agent.c,v 1.213 2016/05/02 08:49:03 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* The authentication agent program.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* Copyright (c) 2000, 2001 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"
#include <sys/param.h> /* MIN MAX */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#ifdef HAVE_SYS_UN_H
# include <sys/un.h>
#endif
#include "openbsd-compat/sys-queue.h"
#ifdef WITH_OPENSSL
#include <openssl/evp.h>
#include "openbsd-compat/openssl-compat.h"
#endif
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_UTIL_H
# include <util.h>
#endif
#include "xmalloc.h"
#include "ssh.h"
#include "rsa.h"
#include "sshbuf.h"
#include "sshkey.h"
#include "authfd.h"
#include "compat.h"
#include "log.h"
#include "misc.h"
#include "digest.h"
#include "ssherr.h"
#ifdef ENABLE_PKCS11
#include "ssh-pkcs11.h"
#endif
#if defined(HAVE_SYS_PRCTL_H)
#include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
#endif
typedef enum {
AUTH_UNUSED,
AUTH_SOCKET,
AUTH_CONNECTION
} sock_type;
typedef struct {
int fd;
sock_type type;
struct sshbuf *input;
struct sshbuf *output;
struct sshbuf *request;
} SocketEntry;
u_int sockets_alloc = 0;
SocketEntry *sockets = NULL;
typedef struct identity {
TAILQ_ENTRY(identity) next;
struct sshkey *key;
char *comment;
char *provider;
time_t death;
u_int confirm;
} Identity;
typedef struct {
int nentries;
TAILQ_HEAD(idqueue, identity) idlist;
} Idtab;
/* private key table, one per protocol version */
Idtab idtable[3];
int max_fd = 0;
/* pid of shell == parent of agent */
pid_t parent_pid = -1;
time_t parent_alive_interval = 0;
/* pid of process for which cleanup_socket is applicable */
pid_t cleanup_pid = 0;
/* pathname and directory for AUTH_SOCKET */
char socket_name[PATH_MAX];
char socket_dir[PATH_MAX];
/* locking */
#define LOCK_SIZE 32
#define LOCK_SALT_SIZE 16
#define LOCK_ROUNDS 1
int locked = 0;
u_char lock_pwhash[LOCK_SIZE];
u_char lock_salt[LOCK_SALT_SIZE];
extern char *__progname;
/* Default lifetime in seconds (0 == forever) */
static long lifetime = 0;
static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
static void
close_socket(SocketEntry *e)
{
close(e->fd);
e->fd = -1;
e->type = AUTH_UNUSED;
sshbuf_free(e->input);
sshbuf_free(e->output);
sshbuf_free(e->request);
}
static void
idtab_init(void)
{
int i;
for (i = 0; i <=2; i++) {
TAILQ_INIT(&idtable[i].idlist);
idtable[i].nentries = 0;
}
}
/* return private key table for requested protocol version */
static Idtab *
idtab_lookup(int version)
{
if (version < 1 || version > 2)
fatal("internal error, bad protocol version %d", version);
return &idtable[version];
}
static void
free_identity(Identity *id)
{
sshkey_free(id->key);
free(id->provider);
free(id->comment);
free(id);
}
/* return matching private key for given public key */
static Identity *
lookup_identity(struct sshkey *key, int version)
{
Identity *id;
Idtab *tab = idtab_lookup(version);
TAILQ_FOREACH(id, &tab->idlist, next) {
if (sshkey_equal(key, id->key))
return (id);
}
return (NULL);
}
/* Check confirmation of keysign request */
static int
confirm_key(Identity *id)
{
char *p;
int ret = -1;
p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
if (p != NULL &&
ask_permission("Allow use of key %s?\nKey fingerprint %s.",
id->comment, p))
ret = 0;
free(p);
return (ret);
}
static void
send_status(SocketEntry *e, int success)
{
int r;
if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
(r = sshbuf_put_u8(e->output, success ?
SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
/* send list of supported public keys to 'client' */
static void
process_request_identities(SocketEntry *e, int version)
{
Idtab *tab = idtab_lookup(version);
Identity *id;
struct sshbuf *msg;
int r;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u8(msg, (version == 1) ?
SSH_AGENT_RSA_IDENTITIES_ANSWER :
SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
(r = sshbuf_put_u32(msg, tab->nentries)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
TAILQ_FOREACH(id, &tab->idlist, next) {
if (id->key->type == KEY_RSA1) {
#ifdef WITH_SSH1
if ((r = sshbuf_put_u32(msg,
BN_num_bits(id->key->rsa->n))) != 0 ||
(r = sshbuf_put_bignum1(msg,
id->key->rsa->e)) != 0 ||
(r = sshbuf_put_bignum1(msg,
id->key->rsa->n)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
#endif
} else {
u_char *blob;
size_t blen;
if ((r = sshkey_to_blob(id->key, &blob, &blen)) != 0) {
error("%s: sshkey_to_blob: %s", __func__,
ssh_err(r));
continue;
}
if ((r = sshbuf_put_string(msg, blob, blen)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
free(blob);
}
if ((r = sshbuf_put_cstring(msg, id->comment)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshbuf_free(msg);
}
#ifdef WITH_SSH1
/* ssh1 only */
static void
process_authentication_challenge1(SocketEntry *e)
{
u_char buf[32], mdbuf[16], session_id[16];
u_int response_type;
BIGNUM *challenge;
Identity *id;
int r, len;
struct sshbuf *msg;
struct ssh_digest_ctx *md;
struct sshkey *key;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((key = sshkey_new(KEY_RSA1)) == NULL)
fatal("%s: sshkey_new failed", __func__);
if ((challenge = BN_new()) == NULL)
fatal("%s: BN_new failed", __func__);
if ((r = sshbuf_get_u32(e->request, NULL)) != 0 || /* ignored */
(r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
(r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0 ||
(r = sshbuf_get_bignum1(e->request, challenge)))
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* Only protocol 1.1 is supported */
if (sshbuf_len(e->request) == 0)
goto failure;
if ((r = sshbuf_get(e->request, session_id, sizeof(session_id))) != 0 ||
(r = sshbuf_get_u32(e->request, &response_type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (response_type != 1)
goto failure;
id = lookup_identity(key, 1);
if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
struct sshkey *private = id->key;
/* Decrypt the challenge using the private key. */
if ((r = rsa_private_decrypt(challenge, challenge,
private->rsa) != 0)) {
fatal("%s: rsa_public_encrypt: %s", __func__,
ssh_err(r));
goto failure; /* XXX ? */
}
/* The response is MD5 of decrypted challenge plus session id */
len = BN_num_bytes(challenge);
if (len <= 0 || len > 32) {
logit("%s: bad challenge length %d", __func__, len);
goto failure;
}
memset(buf, 0, 32);
BN_bn2bin(challenge, buf + 32 - len);
if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
ssh_digest_update(md, buf, 32) < 0 ||
ssh_digest_update(md, session_id, 16) < 0 ||
ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
fatal("%s: md5 failed", __func__);
ssh_digest_free(md);
/* Send the response. */
if ((r = sshbuf_put_u8(msg, SSH_AGENT_RSA_RESPONSE)) != 0 ||
(r = sshbuf_put(msg, mdbuf, sizeof(mdbuf))) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
goto send;
}
failure:
/* Unknown identity or protocol error. Send failure. */
if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
send:
if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshkey_free(key);
BN_clear_free(challenge);
sshbuf_free(msg);
}
#endif
static char *
agent_decode_alg(struct sshkey *key, u_int flags)
{
if (key->type == KEY_RSA) {
if (flags & SSH_AGENT_RSA_SHA2_256)
return "rsa-sha2-256";
else if (flags & SSH_AGENT_RSA_SHA2_512)
return "rsa-sha2-512";
}
return NULL;
}
/* ssh2 only */
static void
process_sign_request2(SocketEntry *e)
{
u_char *blob, *data, *signature = NULL;
size_t blen, dlen, slen = 0;
u_int compat = 0, flags;
int r, ok = -1;
struct sshbuf *msg;
struct sshkey *key;
struct identity *id;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0 ||
(r = sshbuf_get_string(e->request, &data, &dlen)) != 0 ||
(r = sshbuf_get_u32(e->request, &flags)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (flags & SSH_AGENT_OLD_SIGNATURE)
compat = SSH_BUG_SIGBLOB;
if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
error("%s: cannot parse key blob: %s", __func__, ssh_err(r));
goto send;
}
if ((id = lookup_identity(key, 2)) == NULL) {
verbose("%s: %s key not found", __func__, sshkey_type(key));
goto send;
}
if (id->confirm && confirm_key(id) != 0) {
verbose("%s: user refused key", __func__);
goto send;
}
if ((r = sshkey_sign(id->key, &signature, &slen,
data, dlen, agent_decode_alg(key, flags), compat)) != 0) {
error("%s: sshkey_sign: %s", __func__, ssh_err(r));
goto send;
}
/* Success */
ok = 0;
send:
sshkey_free(key);
if (ok == 0) {
if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
(r = sshbuf_put_string(msg, signature, slen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
} else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshbuf_free(msg);
free(data);
free(blob);
free(signature);
}
/* shared */
static void
process_remove_identity(SocketEntry *e, int version)
{
size_t blen;
int r, success = 0;
struct sshkey *key = NULL;
u_char *blob;
#ifdef WITH_SSH1
u_int bits;
#endif /* WITH_SSH1 */
switch (version) {
#ifdef WITH_SSH1
case 1:
if ((key = sshkey_new(KEY_RSA1)) == NULL) {
error("%s: sshkey_new failed", __func__);
return;
}
if ((r = sshbuf_get_u32(e->request, &bits)) != 0 ||
(r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
(r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (bits != sshkey_size(key))
logit("Warning: identity keysize mismatch: "
"actual %u, announced %u",
sshkey_size(key), bits);
break;
#endif /* WITH_SSH1 */
case 2:
if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
error("%s: sshkey_from_blob failed: %s",
__func__, ssh_err(r));
free(blob);
break;
}
if (key != NULL) {
Identity *id = lookup_identity(key, version);
if (id != NULL) {
/*
* We have this key. Free the old key. Since we
* don't want to leave empty slots in the middle of
* the array, we actually free the key there and move
* all the entries between the empty slot and the end
* of the array.
*/
Idtab *tab = idtab_lookup(version);
if (tab->nentries < 1)
fatal("process_remove_identity: "
"internal error: tab->nentries %d",
tab->nentries);
TAILQ_REMOVE(&tab->idlist, id, next);
free_identity(id);
tab->nentries--;
success = 1;
}
sshkey_free(key);
}
send_status(e, success);
}
static void
process_remove_all_identities(SocketEntry *e, int version)
{
Idtab *tab = idtab_lookup(version);
Identity *id;
/* Loop over all identities and clear the keys. */
for (id = TAILQ_FIRST(&tab->idlist); id;
id = TAILQ_FIRST(&tab->idlist)) {
TAILQ_REMOVE(&tab->idlist, id, next);
free_identity(id);
}
/* Mark that there are no identities. */
tab->nentries = 0;
/* Send success. */
send_status(e, 1);
}
/* removes expired keys and returns number of seconds until the next expiry */
static time_t
reaper(void)
{
time_t deadline = 0, now = monotime();
Identity *id, *nxt;
int version;
Idtab *tab;
for (version = 1; version < 3; version++) {
tab = idtab_lookup(version);
for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
nxt = TAILQ_NEXT(id, next);
if (id->death == 0)
continue;
if (now >= id->death) {
debug("expiring key '%s'", id->comment);
TAILQ_REMOVE(&tab->idlist, id, next);
free_identity(id);
tab->nentries--;
} else
deadline = (deadline == 0) ? id->death :
MIN(deadline, id->death);
}
}
if (deadline == 0 || deadline <= now)
return 0;
else
return (deadline - now);
}
/*
* XXX this and the corresponding serialisation function probably belongs
* in key.c
*/
#ifdef WITH_SSH1
static int
agent_decode_rsa1(struct sshbuf *m, struct sshkey **kp)
{
struct sshkey *k = NULL;
int r = SSH_ERR_INTERNAL_ERROR;
*kp = NULL;
if ((k = sshkey_new_private(KEY_RSA1)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_get_u32(m, NULL)) != 0 || /* ignored */
(r = sshbuf_get_bignum1(m, k->rsa->n)) != 0 ||
(r = sshbuf_get_bignum1(m, k->rsa->e)) != 0 ||
(r = sshbuf_get_bignum1(m, k->rsa->d)) != 0 ||
(r = sshbuf_get_bignum1(m, k->rsa->iqmp)) != 0 ||
/* SSH1 and SSL have p and q swapped */
(r = sshbuf_get_bignum1(m, k->rsa->q)) != 0 || /* p */
(r = sshbuf_get_bignum1(m, k->rsa->p)) != 0) /* q */
goto out;
/* Generate additional parameters */
if ((r = rsa_generate_additional_parameters(k->rsa)) != 0)
goto out;
/* enable blinding */
if (RSA_blinding_on(k->rsa, NULL) != 1) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
r = 0; /* success */
out:
if (r == 0)
*kp = k;
else
sshkey_free(k);
return r;
}
#endif /* WITH_SSH1 */
static void
process_add_identity(SocketEntry *e, int version)
{
Idtab *tab = idtab_lookup(version);
Identity *id;
int success = 0, confirm = 0;
u_int seconds;
char *comment = NULL;
time_t death = 0;
struct sshkey *k = NULL;
u_char ctype;
int r = SSH_ERR_INTERNAL_ERROR;
switch (version) {
#ifdef WITH_SSH1
case 1:
r = agent_decode_rsa1(e->request, &k);
break;
#endif /* WITH_SSH1 */
case 2:
r = sshkey_private_deserialize(e->request, &k);
break;
}
if (r != 0 || k == NULL ||
(r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
error("%s: decode private key: %s", __func__, ssh_err(r));
goto err;
}
while (sshbuf_len(e->request)) {
if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) {
error("%s: buffer error: %s", __func__, ssh_err(r));
goto err;
}
switch (ctype) {
case SSH_AGENT_CONSTRAIN_LIFETIME:
if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) {
error("%s: bad lifetime constraint: %s",
__func__, ssh_err(r));
goto err;
}
death = monotime() + seconds;
break;
case SSH_AGENT_CONSTRAIN_CONFIRM:
confirm = 1;
break;
default:
error("%s: Unknown constraint %d", __func__, ctype);
err:
sshbuf_reset(e->request);
free(comment);
sshkey_free(k);
goto send;
}
}
success = 1;
if (lifetime && !death)
death = monotime() + lifetime;
if ((id = lookup_identity(k, version)) == NULL) {
id = xcalloc(1, sizeof(Identity));
id->key = k;
TAILQ_INSERT_TAIL(&tab->idlist, id, next);
/* Increment the number of identities. */
tab->nentries++;
} else {
sshkey_free(k);
free(id->comment);
}
id->comment = comment;
id->death = death;
id->confirm = confirm;
send:
send_status(e, success);
}
/* XXX todo: encrypt sensitive data with passphrase */
static void
process_lock_agent(SocketEntry *e, int lock)
{
int r, success = 0, delay;
char *passwd;
u_char passwdhash[LOCK_SIZE];
static u_int fail_count = 0;
size_t pwlen;
if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (pwlen == 0) {
debug("empty password not supported");
} else if (locked && !lock) {
if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
fatal("bcrypt_pbkdf");
if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) {
debug("agent unlocked");
locked = 0;
fail_count = 0;
explicit_bzero(lock_pwhash, sizeof(lock_pwhash));
success = 1;
} else {
/* delay in 0.1s increments up to 10s */
if (fail_count < 100)
fail_count++;
delay = 100000 * fail_count;
debug("unlock failed, delaying %0.1lf seconds",
(double)delay/1000000);
usleep(delay);
}
explicit_bzero(passwdhash, sizeof(passwdhash));
} else if (!locked && lock) {
debug("agent locked");
locked = 1;
arc4random_buf(lock_salt, sizeof(lock_salt));
if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0)
fatal("bcrypt_pbkdf");
success = 1;
}
explicit_bzero(passwd, pwlen);
free(passwd);
send_status(e, success);
}
static void
no_identities(SocketEntry *e, u_int type)
{
struct sshbuf *msg;
int r;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u8(msg,
(type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
SSH_AGENT_RSA_IDENTITIES_ANSWER :
SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0 ||
(r = sshbuf_put_stringb(e->output, msg)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshbuf_free(msg);
}
#ifdef ENABLE_PKCS11
static void
process_add_smartcard_key(SocketEntry *e)
{
char *provider = NULL, *pin;
int r, i, version, count = 0, success = 0, confirm = 0;
u_int seconds;
time_t death = 0;
u_char type;
struct sshkey **keys = NULL, *k;
Identity *id;
Idtab *tab;
if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
(r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
while (sshbuf_len(e->request)) {
if ((r = sshbuf_get_u8(e->request, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
switch (type) {
case SSH_AGENT_CONSTRAIN_LIFETIME:
if ((r = sshbuf_get_u32(e->request, &seconds)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
death = monotime() + seconds;
break;
case SSH_AGENT_CONSTRAIN_CONFIRM:
confirm = 1;
break;
default:
error("process_add_smartcard_key: "
"Unknown constraint type %d", type);
goto send;
}
}
if (lifetime && !death)
death = monotime() + lifetime;
count = pkcs11_add_provider(provider, pin, &keys);
for (i = 0; i < count; i++) {
k = keys[i];
version = k->type == KEY_RSA1 ? 1 : 2;
tab = idtab_lookup(version);
if (lookup_identity(k, version) == NULL) {
id = xcalloc(1, sizeof(Identity));
id->key = k;
id->provider = xstrdup(provider);
id->comment = xstrdup(provider); /* XXX */
id->death = death;
id->confirm = confirm;
TAILQ_INSERT_TAIL(&tab->idlist, id, next);
tab->nentries++;
success = 1;
} else {
sshkey_free(k);
}
keys[i] = NULL;
}
send:
free(pin);
free(provider);
free(keys);
send_status(e, success);
}
static void
process_remove_smartcard_key(SocketEntry *e)
{
char *provider = NULL, *pin = NULL;
int r, version, success = 0;
Identity *id, *nxt;
Idtab *tab;
if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
(r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
free(pin);
for (version = 1; version < 3; version++) {
tab = idtab_lookup(version);
for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
nxt = TAILQ_NEXT(id, next);
/* Skip file--based keys */
if (id->provider == NULL)
continue;
if (!strcmp(provider, id->provider)) {
TAILQ_REMOVE(&tab->idlist, id, next);
free_identity(id);
tab->nentries--;
}
}
}
if (pkcs11_del_provider(provider) == 0)
success = 1;
else
error("process_remove_smartcard_key:"
" pkcs11_del_provider failed");
free(provider);
send_status(e, success);
}
#endif /* ENABLE_PKCS11 */
/* dispatch incoming messages */
static void
process_message(SocketEntry *e)
{
u_int msg_len;
u_char type;
const u_char *cp;
int r;
if (sshbuf_len(e->input) < 5)
return; /* Incomplete message. */
cp = sshbuf_ptr(e->input);
msg_len = PEEK_U32(cp);
if (msg_len > 256 * 1024) {
close_socket(e);
return;
}
if (sshbuf_len(e->input) < msg_len + 4)
return;
/* move the current input to e->request */
sshbuf_reset(e->request);
if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
(r = sshbuf_get_u8(e->request, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* check wheter agent is locked */
if (locked && type != SSH_AGENTC_UNLOCK) {
sshbuf_reset(e->request);
switch (type) {
case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
case SSH2_AGENTC_REQUEST_IDENTITIES:
/* send empty lists */
no_identities(e, type);
break;
default:
/* send a fail message for all other request types */
send_status(e, 0);
}
return;
}
debug("type %d", type);
switch (type) {
case SSH_AGENTC_LOCK:
case SSH_AGENTC_UNLOCK:
process_lock_agent(e, type == SSH_AGENTC_LOCK);
break;
#ifdef WITH_SSH1
/* ssh1 */
case SSH_AGENTC_RSA_CHALLENGE:
process_authentication_challenge1(e);
break;
case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
process_request_identities(e, 1);
break;
case SSH_AGENTC_ADD_RSA_IDENTITY:
case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
process_add_identity(e, 1);
break;
case SSH_AGENTC_REMOVE_RSA_IDENTITY:
process_remove_identity(e, 1);
break;
#endif
case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
process_remove_all_identities(e, 1); /* safe for !WITH_SSH1 */
break;
/* ssh2 */
case SSH2_AGENTC_SIGN_REQUEST:
process_sign_request2(e);
break;
case SSH2_AGENTC_REQUEST_IDENTITIES:
process_request_identities(e, 2);
break;
case SSH2_AGENTC_ADD_IDENTITY:
case SSH2_AGENTC_ADD_ID_CONSTRAINED:
process_add_identity(e, 2);
break;
case SSH2_AGENTC_REMOVE_IDENTITY:
process_remove_identity(e, 2);
break;
case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
process_remove_all_identities(e, 2);
break;
#ifdef ENABLE_PKCS11
case SSH_AGENTC_ADD_SMARTCARD_KEY:
case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
process_add_smartcard_key(e);
break;
case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
process_remove_smartcard_key(e);
break;
#endif /* ENABLE_PKCS11 */
default:
/* Unknown message. Respond with failure. */
error("Unknown message %d", type);
sshbuf_reset(e->request);
send_status(e, 0);
break;
}
}
static void
new_socket(sock_type type, int fd)
{
u_int i, old_alloc, new_alloc;
set_nonblock(fd);
if (fd > max_fd)
max_fd = fd;
for (i = 0; i < sockets_alloc; i++)
if (sockets[i].type == AUTH_UNUSED) {
sockets[i].fd = fd;
if ((sockets[i].input = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((sockets[i].output = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((sockets[i].request = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
sockets[i].type = type;
return;
}
old_alloc = sockets_alloc;
new_alloc = sockets_alloc + 10;
sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0]));
for (i = old_alloc; i < new_alloc; i++)
sockets[i].type = AUTH_UNUSED;
sockets_alloc = new_alloc;
sockets[old_alloc].fd = fd;
if ((sockets[old_alloc].input = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((sockets[old_alloc].output = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((sockets[old_alloc].request = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
sockets[old_alloc].type = type;
}
static int
prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
struct timeval **tvpp)
{
u_int i, sz;
int n = 0;
static struct timeval tv;
time_t deadline;
for (i = 0; i < sockets_alloc; i++) {
switch (sockets[i].type) {
case AUTH_SOCKET:
case AUTH_CONNECTION:
n = MAX(n, sockets[i].fd);
break;
case AUTH_UNUSED:
break;
default:
fatal("Unknown socket type %d", sockets[i].type);
break;
}
}
sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
if (*fdrp == NULL || sz > *nallocp) {
free(*fdrp);
free(*fdwp);
*fdrp = xmalloc(sz);
*fdwp = xmalloc(sz);
*nallocp = sz;
}
if (n < *fdl)
debug("XXX shrink: %d < %d", n, *fdl);
*fdl = n;
memset(*fdrp, 0, sz);
memset(*fdwp, 0, sz);
for (i = 0; i < sockets_alloc; i++) {
switch (sockets[i].type) {
case AUTH_SOCKET:
case AUTH_CONNECTION:
FD_SET(sockets[i].fd, *fdrp);
if (sshbuf_len(sockets[i].output) > 0)
FD_SET(sockets[i].fd, *fdwp);
break;
default:
break;
}
}
deadline = reaper();
if (parent_alive_interval != 0)
deadline = (deadline == 0) ? parent_alive_interval :
MIN(deadline, parent_alive_interval);
if (deadline == 0) {
*tvpp = NULL;
} else {
tv.tv_sec = deadline;
tv.tv_usec = 0;
*tvpp = &tv;
}
return (1);
}
static void
after_select(fd_set *readset, fd_set *writeset)
{
struct sockaddr_un sunaddr;
socklen_t slen;
char buf[1024];
int len, sock, r;
u_int i, orig_alloc;
uid_t euid;
gid_t egid;
for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
switch (sockets[i].type) {
case AUTH_UNUSED:
break;
case AUTH_SOCKET:
if (FD_ISSET(sockets[i].fd, readset)) {
slen = sizeof(sunaddr);
sock = accept(sockets[i].fd,
(struct sockaddr *)&sunaddr, &slen);
if (sock < 0) {
error("accept from AUTH_SOCKET: %s",
strerror(errno));
break;
}
if (getpeereid(sock, &euid, &egid) < 0) {
error("getpeereid %d failed: %s",
sock, strerror(errno));
close(sock);
break;
}
if ((euid != 0) && (getuid() != euid)) {
error("uid mismatch: "
"peer euid %u != uid %u",
(u_int) euid, (u_int) getuid());
close(sock);
break;
}
new_socket(AUTH_CONNECTION, sock);
}
break;
case AUTH_CONNECTION:
if (sshbuf_len(sockets[i].output) > 0 &&
FD_ISSET(sockets[i].fd, writeset)) {
len = write(sockets[i].fd,
sshbuf_ptr(sockets[i].output),
sshbuf_len(sockets[i].output));
if (len == -1 && (errno == EAGAIN ||
errno == EWOULDBLOCK ||
errno == EINTR))
continue;
if (len <= 0) {
close_socket(&sockets[i]);
break;
}
if ((r = sshbuf_consume(sockets[i].output,
len)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
}
if (FD_ISSET(sockets[i].fd, readset)) {
len = read(sockets[i].fd, buf, sizeof(buf));
if (len == -1 && (errno == EAGAIN ||
errno == EWOULDBLOCK ||
errno == EINTR))
continue;
if (len <= 0) {
close_socket(&sockets[i]);
break;
}
if ((r = sshbuf_put(sockets[i].input,
buf, len)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
explicit_bzero(buf, sizeof(buf));
process_message(&sockets[i]);
}
break;
default:
fatal("Unknown type %d", sockets[i].type);
}
}
static void
cleanup_socket(void)
{
if (cleanup_pid != 0 && getpid() != cleanup_pid)
return;
debug("%s: cleanup", __func__);
if (socket_name[0])
unlink(socket_name);
if (socket_dir[0])
rmdir(socket_dir);
}
void
cleanup_exit(int i)
{
cleanup_socket();
_exit(i);
}
/*ARGSUSED*/
static void
cleanup_handler(int sig)
{
cleanup_socket();
#ifdef ENABLE_PKCS11
pkcs11_terminate();
#endif
_exit(2);
}
static void
check_parent_exists(void)
{
/*
* If our parent has exited then getppid() will return (pid_t)1,
* so testing for that should be safe.
*/
if (parent_pid != -1 && getppid() != parent_pid) {
/* printf("Parent has died - Authentication agent exiting.\n"); */
cleanup_socket();
_exit(2);
}
}
static void
usage(void)
{
fprintf(stderr,
"usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
" [-t life] [command [arg ...]]\n"
" ssh-agent [-c | -s] -k\n");
exit(1);
}
int
main(int ac, char **av)
{
int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
int sock, fd, ch, result, saved_errno;
u_int nalloc;
char *shell, *format, *pidstr, *agentsocket = NULL;
fd_set *readsetp = NULL, *writesetp = NULL;
#ifdef HAVE_SETRLIMIT
struct rlimit rlim;
#endif
extern int optind;
extern char *optarg;
pid_t pid;
char pidstrbuf[1 + 3 * sizeof pid];
struct timeval *tvp = NULL;
size_t len;
mode_t prev_mask;
ssh_malloc_init(); /* must be called before any mallocs */
/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
sanitise_stdfd();
/* drop */
setegid(getgid());
setgid(getgid());
#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
/* Disable ptrace on Linux without sgid bit */
prctl(PR_SET_DUMPABLE, 0);
#endif
#ifdef WITH_OPENSSL
OpenSSL_add_all_algorithms();
#endif
__progname = ssh_get_progname(av[0]);
seed_rng();
while ((ch = getopt(ac, av, "cDdksE:a:t:")) != -1) {
switch (ch) {
case 'E':
fingerprint_hash = ssh_digest_alg_by_name(optarg);
if (fingerprint_hash == -1)
fatal("Invalid hash algorithm \"%s\"", optarg);
break;
case 'c':
if (s_flag)
usage();
c_flag++;
break;
case 'k':
k_flag++;
break;
case 's':
if (c_flag)
usage();
s_flag++;
break;
case 'd':
if (d_flag || D_flag)
usage();
d_flag++;
break;
case 'D':
if (d_flag || D_flag)
usage();
D_flag++;
break;
case 'a':
agentsocket = optarg;
break;
case 't':
if ((lifetime = convtime(optarg)) == -1) {
fprintf(stderr, "Invalid lifetime\n");
usage();
}
break;
default:
usage();
}
}
ac -= optind;
av += optind;
if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
usage();
if (ac == 0 && !c_flag && !s_flag) {
shell = getenv("SHELL");
if (shell != NULL && (len = strlen(shell)) > 2 &&
strncmp(shell + len - 3, "csh", 3) == 0)
c_flag = 1;
}
if (k_flag) {
const char *errstr = NULL;
pidstr = getenv(SSH_AGENTPID_ENV_NAME);
if (pidstr == NULL) {
fprintf(stderr, "%s not set, cannot kill agent\n",
SSH_AGENTPID_ENV_NAME);
exit(1);
}
pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
if (errstr) {
fprintf(stderr,
"%s=\"%s\", which is not a good PID: %s\n",
SSH_AGENTPID_ENV_NAME, pidstr, errstr);
exit(1);
}
if (kill(pid, SIGTERM) == -1) {
perror("kill");
exit(1);
}
format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
printf(format, SSH_AUTHSOCKET_ENV_NAME);
printf(format, SSH_AGENTPID_ENV_NAME);
printf("echo Agent pid %ld killed;\n", (long)pid);
exit(0);
}
parent_pid = getpid();
if (agentsocket == NULL) {
/* Create private directory for agent socket */
mktemp_proto(socket_dir, sizeof(socket_dir));
if (mkdtemp(socket_dir) == NULL) {
perror("mkdtemp: private socket dir");
exit(1);
}
snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
(long)parent_pid);
} else {
/* Try to use specified agent socket */
socket_dir[0] = '\0';
strlcpy(socket_name, agentsocket, sizeof socket_name);
}
/*
* Create socket early so it will exist before command gets run from
* the parent.
*/
prev_mask = umask(0177);
sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
if (sock < 0) {
/* XXX - unix_listener() calls error() not perror() */
*socket_name = '\0'; /* Don't unlink any existing file */
cleanup_exit(1);
}
umask(prev_mask);
/*
* Fork, and have the parent execute the command, if any, or present
* the socket data. The child continues as the authentication agent.
*/
if (D_flag || d_flag) {
log_init(__progname,
d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
SYSLOG_FACILITY_AUTH, 1);
format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
SSH_AUTHSOCKET_ENV_NAME);
printf("echo Agent pid %ld;\n", (long)parent_pid);
fflush(stdout);
goto skip;
}
pid = fork();
if (pid == -1) {
perror("fork");
cleanup_exit(1);
}
if (pid != 0) { /* Parent - execute the given command. */
close(sock);
snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
if (ac == 0) {
format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
SSH_AUTHSOCKET_ENV_NAME);
printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
SSH_AGENTPID_ENV_NAME);
printf("echo Agent pid %ld;\n", (long)pid);
exit(0);
}
if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
perror("setenv");
exit(1);
}
execvp(av[0], av);
perror(av[0]);
exit(1);
}
/* child */
log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
if (setsid() == -1) {
error("setsid: %s", strerror(errno));
cleanup_exit(1);
}
(void)chdir("/");
if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
/* XXX might close listen socket */
(void)dup2(fd, STDIN_FILENO);
(void)dup2(fd, STDOUT_FILENO);
(void)dup2(fd, STDERR_FILENO);
if (fd > 2)
close(fd);
}
#ifdef HAVE_SETRLIMIT
/* deny core dumps, since memory contains unencrypted private keys */
rlim.rlim_cur = rlim.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
error("setrlimit RLIMIT_CORE: %s", strerror(errno));
cleanup_exit(1);
}
#endif
skip:
cleanup_pid = getpid();
#ifdef ENABLE_PKCS11
pkcs11_init(0);
#endif
new_socket(AUTH_SOCKET, sock);
if (ac > 0)
parent_alive_interval = 10;
idtab_init();
signal(SIGPIPE, SIG_IGN);
signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
signal(SIGHUP, cleanup_handler);
signal(SIGTERM, cleanup_handler);
nalloc = 0;
if (pledge("stdio cpath unix id proc exec", NULL) == -1)
fatal("%s: pledge: %s", __progname, strerror(errno));
platform_pledge_agent();
while (1) {
prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
saved_errno = errno;
if (parent_alive_interval != 0)
check_parent_exists();
(void) reaper(); /* remove expired keys */
if (result < 0) {
if (saved_errno == EINTR)
continue;
fatal("select: %s", strerror(saved_errno));
} else if (result > 0)
after_select(readsetp, writesetp);
}
/* NOTREACHED */
}
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