/* $OpenBSD: ssh-agent.c,v 1.221 2017/04/30 23:29:10 djm Exp $ */ /* * 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 #include #include #include #include #include #include #ifdef WITH_OPENSSL #include #endif #include #include #include #include #include #include #include #include #include #include #include #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" #include "match.h" #ifdef ENABLE_PKCS11 #include "ssh-pkcs11.h" #endif #ifndef DEFAULT_PKCS11_WHITELIST # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*" #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; struct idtable { int nentries; TAILQ_HEAD(idqueue, identity) idlist; }; /* private key table */ struct idtable *idtab; 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]; /* PKCS#11 path whitelist */ static char *pkcs11_whitelist; /* 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) { idtab = xcalloc(1, sizeof(*idtab)); TAILQ_INIT(&idtab->idlist); idtab->nentries = 0; } 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) { Identity *id; TAILQ_FOREACH(id, &idtab->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) { Identity *id; struct sshbuf *msg; int r; if ((msg = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || (r = sshbuf_put_u32(msg, idtab->nentries)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); TAILQ_FOREACH(id, &idtab->idlist, next) { if ((r = sshkey_puts(id->key, msg)) != 0 || (r = sshbuf_put_cstring(msg, id->comment)) != 0) { error("%s: put key/comment: %s", __func__, ssh_err(r)); continue; } } if ((r = sshbuf_put_stringb(e->output, msg)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); sshbuf_free(msg); } 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) { const u_char *data; u_char *signature = NULL; size_t dlen, slen = 0; u_int compat = 0, flags; int r, ok = -1; struct sshbuf *msg; struct sshkey *key = NULL; struct identity *id; if ((msg = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); if ((r = sshkey_froms(e->request, &key)) != 0 || (r = sshbuf_get_string_direct(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 ((id = lookup_identity(key)) == 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(signature); } /* shared */ static void process_remove_identity(SocketEntry *e) { int r, success = 0; struct sshkey *key = NULL; Identity *id; if ((r = sshkey_froms(e->request, &key)) != 0) { error("%s: get key: %s", __func__, ssh_err(r)); goto done; } if ((id = lookup_identity(key)) == NULL) { debug("%s: key not found", __func__); goto done; } /* We have this key, free it. */ if (idtab->nentries < 1) fatal("%s: internal error: nentries %d", __func__, idtab->nentries); TAILQ_REMOVE(&idtab->idlist, id, next); free_identity(id); idtab->nentries--; sshkey_free(key); success = 1; done: send_status(e, success); } static void process_remove_all_identities(SocketEntry *e) { Identity *id; /* Loop over all identities and clear the keys. */ for (id = TAILQ_FIRST(&idtab->idlist); id; id = TAILQ_FIRST(&idtab->idlist)) { TAILQ_REMOVE(&idtab->idlist, id, next); free_identity(id); } /* Mark that there are no identities. */ idtab->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; for (id = TAILQ_FIRST(&idtab->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(&idtab->idlist, id, next); free_identity(id); idtab->nentries--; } else deadline = (deadline == 0) ? id->death : MINIMUM(deadline, id->death); } if (deadline == 0 || deadline <= now) return 0; else return (deadline - now); } static void process_add_identity(SocketEntry *e) { 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; if ((r = sshkey_private_deserialize(e->request, &k)) != 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)) == NULL) { id = xcalloc(1, sizeof(Identity)); id->key = k; TAILQ_INSERT_TAIL(&idtab->idlist, id, next); /* Increment the number of identities. */ idtab->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) { struct sshbuf *msg; int r; if ((msg = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); if ((r = sshbuf_put_u8(msg, 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, canonical_provider[PATH_MAX]; int r, i, count = 0, success = 0, confirm = 0; u_int seconds; time_t death = 0; u_char type; struct sshkey **keys = NULL, *k; Identity *id; 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("%s: Unknown constraint type %d", __func__, type); goto send; } } if (realpath(provider, canonical_provider) == NULL) { verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", provider, strerror(errno)); goto send; } if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) { verbose("refusing PKCS#11 add of \"%.100s\": " "provider not whitelisted", canonical_provider); goto send; } debug("%s: add %.100s", __func__, canonical_provider); if (lifetime && !death) death = monotime() + lifetime; count = pkcs11_add_provider(canonical_provider, pin, &keys); for (i = 0; i < count; i++) { k = keys[i]; if (lookup_identity(k) == NULL) { id = xcalloc(1, sizeof(Identity)); id->key = k; id->provider = xstrdup(canonical_provider); id->comment = xstrdup(canonical_provider); /* XXX */ id->death = death; id->confirm = confirm; TAILQ_INSERT_TAIL(&idtab->idlist, id, next); idtab->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, canonical_provider[PATH_MAX]; int r, success = 0; Identity *id, *nxt; 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); if (realpath(provider, canonical_provider) == NULL) { verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", provider, strerror(errno)); goto send; } debug("%s: remove %.100s", __func__, canonical_provider); for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { nxt = TAILQ_NEXT(id, next); /* Skip file--based keys */ if (id->provider == NULL) continue; if (!strcmp(canonical_provider, id->provider)) { TAILQ_REMOVE(&idtab->idlist, id, next); free_identity(id); idtab->nentries--; } } if (pkcs11_del_provider(canonical_provider) == 0) success = 1; else error("%s: pkcs11_del_provider failed", __func__); send: 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 SSH2_AGENTC_REQUEST_IDENTITIES: /* send empty lists */ no_identities(e); 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; case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: process_remove_all_identities(e); /* 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); break; case SSH2_AGENTC_ADD_IDENTITY: case SSH2_AGENTC_ADD_ID_CONSTRAINED: process_add_identity(e); break; case SSH2_AGENTC_REMOVE_IDENTITY: process_remove_identity(e); break; case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: process_remove_all_identities(e); 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 = MAXIMUM(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 : MINIMUM(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 == 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 == 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" " [-P pkcs11_whitelist] [-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; struct rlimit rlim; 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()); #ifdef WITH_OPENSSL OpenSSL_add_all_algorithms(); #endif while ((ch = getopt(ac, av, "cDdksE:a:P: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 'P': if (pkcs11_whitelist != NULL) fatal("-P option already specified"); pkcs11_whitelist = xstrdup(optarg); 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 (pkcs11_whitelist == NULL) pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST); 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); } /* 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); } 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 rpath cpath unix id proc exec", NULL) == -1) fatal("%s: pledge: %s", __progname, strerror(errno)); 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 */ }