diff options
Diffstat (limited to 'ssh-agent.c')
| -rw-r--r-- | ssh-agent.c | 1254 |
1 files changed, 1254 insertions, 0 deletions
diff --git a/ssh-agent.c b/ssh-agent.c new file mode 100644 index 000000000000..ef95eb878f39 --- /dev/null +++ b/ssh-agent.c @@ -0,0 +1,1254 @@ +/* $OpenBSD: ssh-agent.c,v 1.153 2006/10/06 02:29:19 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/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 <stdarg.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 */ +} |