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openssh/ssh-agent.c
Damien Miller 9ab00b44c1 - stevesk@cvs.openbsd.org 2006/08/04 20:46:05 
[monitor.c session.c ssh-agent.c]
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2006-08-05 12:40:11 +10:00

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/* $OpenBSD: ssh-agent.c,v 1.152 2006/08/04 20:46:05 stevesk 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/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"
#include <openssl/evp.h>
#include <openssl/md5.h>
#include <errno.h>
#include <fcntl.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include "xmalloc.h"
#include "ssh.h"
#include "rsa.h"
#include "buffer.h"
#include "key.h"
#include "authfd.h"
#include "compat.h"
#include "log.h"
#include "misc.h"
#ifdef SMARTCARD
#include "scard.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;
Buffer input;
Buffer output;
Buffer request;
} SocketEntry;
u_int sockets_alloc = 0;
SocketEntry *sockets = NULL;
typedef struct identity {
TAILQ_ENTRY(identity) next;
Key *key;
char *comment;
u_int 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;
/* pathname and directory for AUTH_SOCKET */
char socket_name[MAXPATHLEN];
char socket_dir[MAXPATHLEN];
/* locking */
int locked = 0;
char *lock_passwd = NULL;
extern char *__progname;
/* Default lifetime (0 == forever) */
static int lifetime = 0;
static void
close_socket(SocketEntry *e)
{
close(e->fd);
e->fd = -1;
e->type = AUTH_UNUSED;
buffer_free(&e->input);
buffer_free(&e->output);
buffer_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)
{
key_free(id->key);
xfree(id->comment);
xfree(id);
}
/* return matching private key for given public key */
static Identity *
lookup_identity(Key *key, int version)
{
Identity *id;
Idtab *tab = idtab_lookup(version);
TAILQ_FOREACH(id, &tab->idlist, next) {
if (key_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 = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
id->comment, p))
ret = 0;
xfree(p);
return (ret);
}
/* send list of supported public keys to 'client' */
static void
process_request_identities(SocketEntry *e, int version)
{
Idtab *tab = idtab_lookup(version);
Identity *id;
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg, (version == 1) ?
SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
buffer_put_int(&msg, tab->nentries);
TAILQ_FOREACH(id, &tab->idlist, next) {
if (id->key->type == KEY_RSA1) {
buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
buffer_put_bignum(&msg, id->key->rsa->e);
buffer_put_bignum(&msg, id->key->rsa->n);
} else {
u_char *blob;
u_int blen;
key_to_blob(id->key, &blob, &blen);
buffer_put_string(&msg, blob, blen);
xfree(blob);
}
buffer_put_cstring(&msg, id->comment);
}
buffer_put_int(&e->output, buffer_len(&msg));
buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
buffer_free(&msg);
}
/* 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 i, len;
Buffer msg;
MD5_CTX md;
Key *key;
buffer_init(&msg);
key = key_new(KEY_RSA1);
if ((challenge = BN_new()) == NULL)
fatal("process_authentication_challenge1: BN_new failed");
(void) buffer_get_int(&e->request); /* ignored */
buffer_get_bignum(&e->request, key->rsa->e);
buffer_get_bignum(&e->request, key->rsa->n);
buffer_get_bignum(&e->request, challenge);
/* Only protocol 1.1 is supported */
if (buffer_len(&e->request) == 0)
goto failure;
buffer_get(&e->request, session_id, 16);
response_type = buffer_get_int(&e->request);
if (response_type != 1)
goto failure;
id = lookup_identity(key, 1);
if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
Key *private = id->key;
/* Decrypt the challenge using the private key. */
if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
goto failure;
/* The response is MD5 of decrypted challenge plus session id. */
len = BN_num_bytes(challenge);
if (len <= 0 || len > 32) {
logit("process_authentication_challenge: bad challenge length %d", len);
goto failure;
}
memset(buf, 0, 32);
BN_bn2bin(challenge, buf + 32 - len);
MD5_Init(&md);
MD5_Update(&md, buf, 32);
MD5_Update(&md, session_id, 16);
MD5_Final(mdbuf, &md);
/* Send the response. */
buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
for (i = 0; i < 16; i++)
buffer_put_char(&msg, mdbuf[i]);
goto send;
}
failure:
/* Unknown identity or protocol error. Send failure. */
buffer_put_char(&msg, SSH_AGENT_FAILURE);
send:
buffer_put_int(&e->output, buffer_len(&msg));
buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
key_free(key);
BN_clear_free(challenge);
buffer_free(&msg);
}
/* ssh2 only */
static void
process_sign_request2(SocketEntry *e)
{
u_char *blob, *data, *signature = NULL;
u_int blen, dlen, slen = 0;
extern int datafellows;
int ok = -1, flags;
Buffer msg;
Key *key;
datafellows = 0;
blob = buffer_get_string(&e->request, &blen);
data = buffer_get_string(&e->request, &dlen);
flags = buffer_get_int(&e->request);
if (flags & SSH_AGENT_OLD_SIGNATURE)
datafellows = SSH_BUG_SIGBLOB;
key = key_from_blob(blob, blen);
if (key != NULL) {
Identity *id = lookup_identity(key, 2);
if (id != NULL && (!id->confirm || confirm_key(id) == 0))
ok = key_sign(id->key, &signature, &slen, data, dlen);
key_free(key);
}
buffer_init(&msg);
if (ok == 0) {
buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
buffer_put_string(&msg, signature, slen);
} else {
buffer_put_char(&msg, SSH_AGENT_FAILURE);
}
buffer_put_int(&e->output, buffer_len(&msg));
buffer_append(&e->output, buffer_ptr(&msg),
buffer_len(&msg));
buffer_free(&msg);
xfree(data);
xfree(blob);
if (signature != NULL)
xfree(signature);
}
/* shared */
static void
process_remove_identity(SocketEntry *e, int version)
{
u_int blen, bits;
int success = 0;
Key *key = NULL;
u_char *blob;
switch (version) {
case 1:
key = key_new(KEY_RSA1);
bits = buffer_get_int(&e->request);
buffer_get_bignum(&e->request, key->rsa->e);
buffer_get_bignum(&e->request, key->rsa->n);
if (bits != key_size(key))
logit("Warning: identity keysize mismatch: actual %u, announced %u",
key_size(key), bits);
break;
case 2:
blob = buffer_get_string(&e->request, &blen);
key = key_from_blob(blob, blen);
xfree(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;
}
key_free(key);
}
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output,
success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
}
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. */
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
}
static void
reaper(void)
{
u_int now = time(NULL);
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 && now >= id->death) {
TAILQ_REMOVE(&tab->idlist, id, next);
free_identity(id);
tab->nentries--;
}
}
}
}
static void
process_add_identity(SocketEntry *e, int version)
{
Idtab *tab = idtab_lookup(version);
int type, success = 0, death = 0, confirm = 0;
char *type_name, *comment;
Key *k = NULL;
switch (version) {
case 1:
k = key_new_private(KEY_RSA1);
(void) buffer_get_int(&e->request); /* ignored */
buffer_get_bignum(&e->request, k->rsa->n);
buffer_get_bignum(&e->request, k->rsa->e);
buffer_get_bignum(&e->request, k->rsa->d);
buffer_get_bignum(&e->request, k->rsa->iqmp);
/* SSH and SSL have p and q swapped */
buffer_get_bignum(&e->request, k->rsa->q); /* p */
buffer_get_bignum(&e->request, k->rsa->p); /* q */
/* Generate additional parameters */
rsa_generate_additional_parameters(k->rsa);
break;
case 2:
type_name = buffer_get_string(&e->request, NULL);
type = key_type_from_name(type_name);
xfree(type_name);
switch (type) {
case KEY_DSA:
k = key_new_private(type);
buffer_get_bignum2(&e->request, k->dsa->p);
buffer_get_bignum2(&e->request, k->dsa->q);
buffer_get_bignum2(&e->request, k->dsa->g);
buffer_get_bignum2(&e->request, k->dsa->pub_key);
buffer_get_bignum2(&e->request, k->dsa->priv_key);
break;
case KEY_RSA:
k = key_new_private(type);
buffer_get_bignum2(&e->request, k->rsa->n);
buffer_get_bignum2(&e->request, k->rsa->e);
buffer_get_bignum2(&e->request, k->rsa->d);
buffer_get_bignum2(&e->request, k->rsa->iqmp);
buffer_get_bignum2(&e->request, k->rsa->p);
buffer_get_bignum2(&e->request, k->rsa->q);
/* Generate additional parameters */
rsa_generate_additional_parameters(k->rsa);
break;
default:
buffer_clear(&e->request);
goto send;
}
break;
}
/* enable blinding */
switch (k->type) {
case KEY_RSA:
case KEY_RSA1:
if (RSA_blinding_on(k->rsa, NULL) != 1) {
error("process_add_identity: RSA_blinding_on failed");
key_free(k);
goto send;
}
break;
}
comment = buffer_get_string(&e->request, NULL);
if (k == NULL) {
xfree(comment);
goto send;
}
success = 1;
while (buffer_len(&e->request)) {
switch (buffer_get_char(&e->request)) {
case SSH_AGENT_CONSTRAIN_LIFETIME:
death = time(NULL) + buffer_get_int(&e->request);
break;
case SSH_AGENT_CONSTRAIN_CONFIRM:
confirm = 1;
break;
default:
break;
}
}
if (lifetime && !death)
death = time(NULL) + lifetime;
if (lookup_identity(k, version) == NULL) {
Identity *id = xmalloc(sizeof(Identity));
id->key = k;
id->comment = comment;
id->death = death;
id->confirm = confirm;
TAILQ_INSERT_TAIL(&tab->idlist, id, next);
/* Increment the number of identities. */
tab->nentries++;
} else {
key_free(k);
xfree(comment);
}
send:
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output,
success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
}
/* XXX todo: encrypt sensitive data with passphrase */
static void
process_lock_agent(SocketEntry *e, int lock)
{
int success = 0;
char *passwd;
passwd = buffer_get_string(&e->request, NULL);
if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
locked = 0;
memset(lock_passwd, 0, strlen(lock_passwd));
xfree(lock_passwd);
lock_passwd = NULL;
success = 1;
} else if (!locked && lock) {
locked = 1;
lock_passwd = xstrdup(passwd);
success = 1;
}
memset(passwd, 0, strlen(passwd));
xfree(passwd);
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output,
success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
}
static void
no_identities(SocketEntry *e, u_int type)
{
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg,
(type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
buffer_put_int(&msg, 0);
buffer_put_int(&e->output, buffer_len(&msg));
buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
buffer_free(&msg);
}
#ifdef SMARTCARD
static void
process_add_smartcard_key (SocketEntry *e)
{
char *sc_reader_id = NULL, *pin;
int i, version, success = 0, death = 0, confirm = 0;
Key **keys, *k;
Identity *id;
Idtab *tab;
sc_reader_id = buffer_get_string(&e->request, NULL);
pin = buffer_get_string(&e->request, NULL);
while (buffer_len(&e->request)) {
switch (buffer_get_char(&e->request)) {
case SSH_AGENT_CONSTRAIN_LIFETIME:
death = time(NULL) + buffer_get_int(&e->request);
break;
case SSH_AGENT_CONSTRAIN_CONFIRM:
confirm = 1;
break;
default:
break;
}
}
if (lifetime && !death)
death = time(NULL) + lifetime;
keys = sc_get_keys(sc_reader_id, pin);
xfree(sc_reader_id);
xfree(pin);
if (keys == NULL || keys[0] == NULL) {
error("sc_get_keys failed");
goto send;
}
for (i = 0; keys[i] != NULL; i++) {
k = keys[i];
version = k->type == KEY_RSA1 ? 1 : 2;
tab = idtab_lookup(version);
if (lookup_identity(k, version) == NULL) {
id = xmalloc(sizeof(Identity));
id->key = k;
id->comment = sc_get_key_label(k);
id->death = death;
id->confirm = confirm;
TAILQ_INSERT_TAIL(&tab->idlist, id, next);
tab->nentries++;
success = 1;
} else {
key_free(k);
}
keys[i] = NULL;
}
xfree(keys);
send:
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output,
success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
}
static void
process_remove_smartcard_key(SocketEntry *e)
{
char *sc_reader_id = NULL, *pin;
int i, version, success = 0;
Key **keys, *k = NULL;
Identity *id;
Idtab *tab;
sc_reader_id = buffer_get_string(&e->request, NULL);
pin = buffer_get_string(&e->request, NULL);
keys = sc_get_keys(sc_reader_id, pin);
xfree(sc_reader_id);
xfree(pin);
if (keys == NULL || keys[0] == NULL) {
error("sc_get_keys failed");
goto send;
}
for (i = 0; keys[i] != NULL; i++) {
k = keys[i];
version = k->type == KEY_RSA1 ? 1 : 2;
if ((id = lookup_identity(k, version)) != NULL) {
tab = idtab_lookup(version);
TAILQ_REMOVE(&tab->idlist, id, next);
tab->nentries--;
free_identity(id);
success = 1;
}
key_free(k);
keys[i] = NULL;
}
xfree(keys);
send:
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output,
success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
}
#endif /* SMARTCARD */
/* dispatch incoming messages */
static void
process_message(SocketEntry *e)
{
u_int msg_len, type;
u_char *cp;
/* kill dead keys */
reaper();
if (buffer_len(&e->input) < 5)
return; /* Incomplete message. */
cp = buffer_ptr(&e->input);
msg_len = get_u32(cp);
if (msg_len > 256 * 1024) {
close_socket(e);
return;
}
if (buffer_len(&e->input) < msg_len + 4)
return;
/* move the current input to e->request */
buffer_consume(&e->input, 4);
buffer_clear(&e->request);
buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
buffer_consume(&e->input, msg_len);
type = buffer_get_char(&e->request);
/* check wheter agent is locked */
if (locked && type != SSH_AGENTC_UNLOCK) {
buffer_clear(&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 */
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output, SSH_AGENT_FAILURE);
}
return;
}
debug("type %d", type);
switch (type) {
case SSH_AGENTC_LOCK:
case SSH_AGENTC_UNLOCK:
process_lock_agent(e, type == SSH_AGENTC_LOCK);
break;
/* 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;
case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
process_remove_all_identities(e, 1);
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 SMARTCARD
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 /* SMARTCARD */
default:
/* Unknown message. Respond with failure. */
error("Unknown message %d", type);
buffer_clear(&e->request);
buffer_put_int(&e->output, 1);
buffer_put_char(&e->output, SSH_AGENT_FAILURE);
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;
buffer_init(&sockets[i].input);
buffer_init(&sockets[i].output);
buffer_init(&sockets[i].request);
sockets[i].type = type;
return;
}
old_alloc = sockets_alloc;
new_alloc = sockets_alloc + 10;
sockets = xrealloc(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;
buffer_init(&sockets[old_alloc].input);
buffer_init(&sockets[old_alloc].output);
buffer_init(&sockets[old_alloc].request);
sockets[old_alloc].type = type;
}
static int
prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
{
u_int i, sz;
int n = 0;
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) {
if (*fdrp)
xfree(*fdrp);
if (*fdwp)
xfree(*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 (buffer_len(&sockets[i].output) > 0)
FD_SET(sockets[i].fd, *fdwp);
break;
default:
break;
}
}
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;
u_int i;
uid_t euid;
gid_t egid;
for (i = 0; i < sockets_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 (buffer_len(&sockets[i].output) > 0 &&
FD_ISSET(sockets[i].fd, writeset)) {
do {
len = write(sockets[i].fd,
buffer_ptr(&sockets[i].output),
buffer_len(&sockets[i].output));
if (len == -1 && (errno == EAGAIN ||
errno == EINTR))
continue;
break;
} while (1);
if (len <= 0) {
close_socket(&sockets[i]);
break;
}
buffer_consume(&sockets[i].output, len);
}
if (FD_ISSET(sockets[i].fd, readset)) {
do {
len = read(sockets[i].fd, buf, sizeof(buf));
if (len == -1 && (errno == EAGAIN ||
errno == EINTR))
continue;
break;
} while (1);
if (len <= 0) {
close_socket(&sockets[i]);
break;
}
buffer_append(&sockets[i].input, buf, len);
process_message(&sockets[i]);
}
break;
default:
fatal("Unknown type %d", sockets[i].type);
}
}
static void
cleanup_socket(void)
{
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();
_exit(2);
}
/*ARGSUSED*/
static void
check_parent_exists(int sig)
{
int save_errno = errno;
if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
/* printf("Parent has died - Authentication agent exiting.\n"); */
cleanup_handler(sig); /* safe */
}
mysignal(SIGALRM, check_parent_exists);
alarm(10);
errno = save_errno;
}
static void
usage(void)
{
fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
__progname);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
fprintf(stderr, " -k Kill the current agent.\n");
fprintf(stderr, " -d Debug mode.\n");
fprintf(stderr, " -a socket Bind agent socket to given name.\n");
fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
exit(1);
}
int
main(int ac, char **av)
{
int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
int sock, fd, ch;
u_int nalloc;
char *shell, *format, *pidstr, *agentsocket = NULL;
fd_set *readsetp = NULL, *writesetp = NULL;
struct sockaddr_un sunaddr;
#ifdef HAVE_SETRLIMIT
struct rlimit rlim;
#endif
int prev_mask;
extern int optind;
extern char *optarg;
pid_t pid;
char pidstrbuf[1 + 3 * sizeof pid];
/* 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
SSLeay_add_all_algorithms();
__progname = ssh_get_progname(av[0]);
init_rng();
seed_rng();
while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
switch (ch) {
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)
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))
usage();
if (ac == 0 && !c_flag && !s_flag) {
shell = getenv("SHELL");
if (shell != NULL &&
strncmp(shell + strlen(shell) - 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 */
strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", 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.
*/
sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0) {
perror("socket");
*socket_name = '\0'; /* Don't unlink any existing file */
cleanup_exit(1);
}
memset(&sunaddr, 0, sizeof(sunaddr));
sunaddr.sun_family = AF_UNIX;
strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
prev_mask = umask(0177);
if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
perror("bind");
*socket_name = '\0'; /* Don't unlink any existing file */
umask(prev_mask);
cleanup_exit(1);
}
umask(prev_mask);
if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
perror("listen");
cleanup_exit(1);
}
/*
* 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) {
log_init(__progname, SYSLOG_LEVEL_DEBUG1, 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);
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:
new_socket(AUTH_SOCKET, sock);
if (ac > 0) {
mysignal(SIGALRM, check_parent_exists);
alarm(10);
}
idtab_init();
if (!d_flag)
signal(SIGINT, SIG_IGN);
signal(SIGPIPE, SIG_IGN);
signal(SIGHUP, cleanup_handler);
signal(SIGTERM, cleanup_handler);
nalloc = 0;
while (1) {
prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
if (errno == EINTR)
continue;
fatal("select: %s", strerror(errno));
}
after_select(readsetp, writesetp);
}
/* NOTREACHED */
}
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