/* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , 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 "openbsd-compat/sys-queue.h" RCSID("$OpenBSD: ssh-agent.c,v 1.120 2004/08/11 21:43:05 avsm Exp $"); #include #include #include "ssh.h" #include "rsa.h" #include "buffer.h" #include "bufaux.h" #include "xmalloc.h" #include "getput.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 /* 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[1024]; char socket_dir[1024]; /* 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, prompt[1024]; int ret = -1; p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX); snprintf(prompt, sizeof(prompt), "Allow use of key %s?\n" "Key fingerprint %s.", id->comment, p); xfree(p); p = read_passphrase(prompt, RP_ALLOW_EOF); if (p != NULL) { /* * Accept empty responses and responses consisting * of the word "yes" as affirmative. */ if (*p == '\0' || *p == '\n' || strcasecmp(p, "yes") == 0) 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_32BIT(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; if (sockets) sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0])); else sockets = xmalloc(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); } static void cleanup_handler(int sig) { cleanup_socket(); _exit(2); } 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 #ifdef HAVE_CYGWIN int prev_mask; #endif extern int optind; extern char *optarg; pid_t pid; char pidstrbuf[1 + 3 * sizeof pid]; /* 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) { 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 = atoi(pidstr); if (pid < 1) { fprintf(stderr, "%s=\"%s\", which is not a good PID\n", SSH_AGENTPID_ENV_NAME, pidstr); 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"); cleanup_exit(1); } memset(&sunaddr, 0, sizeof(sunaddr)); sunaddr.sun_family = AF_UNIX; strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path)); #ifdef HAVE_CYGWIN prev_mask = umask(0177); #endif if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { perror("bind"); #ifdef HAVE_CYGWIN umask(prev_mask); #endif cleanup_exit(1); } #ifdef HAVE_CYGWIN umask(prev_mask); #endif 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 */ }