X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/ee900f87daf4d85cdf03c55550f8daf5a6ed1e08..3165286982a9ab28fd80125b2fb2608716fb37db:/ssh-agent.c diff --git a/ssh-agent.c b/ssh-agent.c index 536db2de..e43faae4 100644 --- a/ssh-agent.c +++ b/ssh-agent.c @@ -1,3 +1,4 @@ +/* $OpenBSD: ssh-agent.c,v 1.151 2006/08/03 03:34:42 deraadt Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -34,27 +35,53 @@ */ #include "includes.h" -#include "openbsd-compat/fake-queue.h" -RCSID("$OpenBSD: ssh-agent.c,v 1.94 2002/06/15 01:27:48 markus Exp $"); + +#include +#include +#include +#include +#include +#ifdef HAVE_SYS_TIME_H +# include +#endif +#ifdef HAVE_SYS_UN_H +# include +#endif +#include "openbsd-compat/sys-queue.h" #include #include +#include +#include +#ifdef HAVE_PATHS_H +# include +#endif +#include +#include +#include +#include +#include +#include + +#include "xmalloc.h" #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, @@ -77,6 +104,7 @@ typedef struct identity { Key *key; char *comment; u_int death; + u_int confirm; } Identity; typedef struct { @@ -93,23 +121,34 @@ int max_fd = 0; pid_t parent_pid = -1; /* pathname and directory for AUTH_SOCKET */ -char socket_name[1024]; -char socket_dir[1024]; +char socket_name[MAXPATHLEN]; +char socket_dir[MAXPATHLEN]; /* locking */ int locked = 0; char *lock_passwd = NULL; -#ifdef HAVE___PROGNAME extern char *__progname; -#else -char *__progname; -#endif + +/* 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; @@ -147,13 +186,29 @@ lookup_identity(Key *key, int version) 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); - Buffer msg; Identity *id; + Buffer msg; buffer_init(&msg); buffer_put_char(&msg, (version == 1) ? @@ -182,21 +237,21 @@ process_request_identities(SocketEntry *e, int version) static void process_authentication_challenge1(SocketEntry *e) { - Identity *id; - Key *key; + 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; - u_char buf[32], mdbuf[16], session_id[16]; - u_int response_type; + Key *key; buffer_init(&msg); key = key_new(KEY_RSA1); if ((challenge = BN_new()) == NULL) fatal("process_authentication_challenge1: BN_new failed"); - buffer_get_int(&e->request); /* ignored */ + (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); @@ -210,7 +265,7 @@ process_authentication_challenge1(SocketEntry *e) goto failure; id = lookup_identity(key, 1); - if (id != NULL) { + 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) @@ -219,7 +274,7 @@ process_authentication_challenge1(SocketEntry *e) /* The response is MD5 of decrypted challenge plus session id. */ len = BN_num_bytes(challenge); if (len <= 0 || len > 32) { - log("process_authentication_challenge: bad challenge length %d", len); + logit("process_authentication_challenge: bad challenge length %d", len); goto failure; } memset(buf, 0, 32); @@ -251,13 +306,12 @@ send: static void process_sign_request2(SocketEntry *e) { - extern int datafellows; - Key *key; u_char *blob, *data, *signature = NULL; u_int blen, dlen, slen = 0; - int flags; + extern int datafellows; + int ok = -1, flags; Buffer msg; - int ok = -1; + Key *key; datafellows = 0; @@ -271,10 +325,10 @@ process_sign_request2(SocketEntry *e) key = key_from_blob(blob, blen); if (key != NULL) { Identity *id = lookup_identity(key, 2); - if (id != NULL) + if (id != NULL && (!id->confirm || confirm_key(id) == 0)) ok = key_sign(id->key, &signature, &slen, data, dlen); + key_free(key); } - key_free(key); buffer_init(&msg); if (ok == 0) { buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE); @@ -296,11 +350,10 @@ process_sign_request2(SocketEntry *e) static void process_remove_identity(SocketEntry *e, int version) { + u_int blen, bits; + int success = 0; Key *key = NULL; u_char *blob; - u_int blen; - u_int bits; - int success = 0; switch (version) { case 1: @@ -310,7 +363,7 @@ process_remove_identity(SocketEntry *e, int version) buffer_get_bignum(&e->request, key->rsa->n); if (bits != key_size(key)) - log("Warning: identity keysize mismatch: actual %d, announced %d", + logit("Warning: identity keysize mismatch: actual %u, announced %u", key_size(key), bits); break; case 2: @@ -324,7 +377,7 @@ process_remove_identity(SocketEntry *e, int 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 + * 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. @@ -365,16 +418,15 @@ process_remove_all_identities(SocketEntry *e, int version) /* Send success. */ buffer_put_int(&e->output, 1); buffer_put_char(&e->output, SSH_AGENT_SUCCESS); - return; } static void reaper(void) { - Idtab *tab; + u_int now = time(NULL); Identity *id, *nxt; int version; - u_int now = time(NULL); + Idtab *tab; for (version = 1; version < 3; version++) { tab = idtab_lookup(version); @@ -392,16 +444,15 @@ reaper(void) static void process_add_identity(SocketEntry *e, int version) { - Key *k = NULL; - char *type_name; - char *comment; - int type, success = 0, death = 0; 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); - buffer_get_int(&e->request); /* ignored */ + (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); @@ -445,6 +496,17 @@ process_add_identity(SocketEntry *e, int version) } 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); @@ -456,15 +518,21 @@ process_add_identity(SocketEntry *e, int version) 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++; @@ -482,8 +550,8 @@ send: static void process_lock_agent(SocketEntry *e, int lock) { - char *passwd; int success = 0; + char *passwd; passwd = buffer_get_string(&e->request, NULL); if (locked && !lock && strcmp(passwd, lock_passwd) == 0) { @@ -499,11 +567,10 @@ process_lock_agent(SocketEntry *e, int lock) } 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); - return; } static void @@ -525,14 +592,30 @@ no_identities(SocketEntry *e, u_int type) 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; - Key **keys, *k; - char *sc_reader_id = NULL, *pin; - int i, version, success = 0; 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); @@ -548,8 +631,9 @@ process_add_smartcard_key (SocketEntry *e) if (lookup_identity(k, version) == NULL) { id = xmalloc(sizeof(Identity)); id->key = k; - id->comment = xstrdup("smartcard key"); - id->death = 0; + id->comment = sc_get_key_label(k); + id->death = death; + id->confirm = confirm; TAILQ_INSERT_TAIL(&tab->idlist, id, next); tab->nentries++; success = 1; @@ -568,11 +652,11 @@ send: static void process_remove_smartcard_key(SocketEntry *e) { - Identity *id; - Idtab *tab; - Key **keys, *k = NULL; 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); @@ -610,8 +694,7 @@ send: static void process_message(SocketEntry *e) { - u_int msg_len; - u_int type; + u_int msg_len, type; u_char *cp; /* kill dead keys */ @@ -620,14 +703,9 @@ process_message(SocketEntry *e) if (buffer_len(&e->input) < 5) return; /* Incomplete message. */ cp = buffer_ptr(&e->input); - msg_len = GET_32BIT(cp); + msg_len = get_u32(cp); if (msg_len > 256 * 1024) { - shutdown(e->fd, SHUT_RDWR); - close(e->fd); - e->type = AUTH_UNUSED; - buffer_free(&e->input); - buffer_free(&e->output); - buffer_free(&e->request); + close_socket(e); return; } if (buffer_len(&e->input) < msg_len + 4) @@ -699,6 +777,7 @@ process_message(SocketEntry *e) 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: @@ -718,9 +797,9 @@ process_message(SocketEntry *e) static void new_socket(sock_type type, int fd) { - u_int i, old_alloc; - if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) - error("fcntl O_NONBLOCK: %s", strerror(errno)); + u_int i, old_alloc, new_alloc; + + set_nonblock(fd); if (fd > max_fd) max_fd = fd; @@ -728,29 +807,27 @@ new_socket(sock_type type, int fd) for (i = 0; i < sockets_alloc; i++) if (sockets[i].type == AUTH_UNUSED) { sockets[i].fd = fd; - sockets[i].type = type; buffer_init(&sockets[i].input); buffer_init(&sockets[i].output); buffer_init(&sockets[i].request); + sockets[i].type = type; return; } old_alloc = sockets_alloc; - sockets_alloc += 10; - if (sockets) - sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0])); - else - sockets = xmalloc(sockets_alloc * sizeof(sockets[0])); - for (i = old_alloc; i < sockets_alloc; i++) + 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[old_alloc].type = type; + 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, int *nallocp) +prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp) { u_int i, sz; int n = 0; @@ -803,11 +880,13 @@ prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, int *nallocp) static void after_select(fd_set *readset, fd_set *writeset) { - u_int i; - int len, sock; + struct sockaddr_un sunaddr; socklen_t slen; char buf[1024]; - struct sockaddr_un sunaddr; + int len, sock; + u_int i; + uid_t euid; + gid_t egid; for (i = 0; i < sockets_alloc; i++) switch (sockets[i].type) { @@ -817,12 +896,25 @@ after_select(fd_set *readset, fd_set *writeset) if (FD_ISSET(sockets[i].fd, readset)) { slen = sizeof(sunaddr); sock = accept(sockets[i].fd, - (struct sockaddr *) &sunaddr, &slen); + (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; @@ -839,12 +931,7 @@ after_select(fd_set *readset, fd_set *writeset) break; } while (1); if (len <= 0) { - shutdown(sockets[i].fd, SHUT_RDWR); - close(sockets[i].fd); - sockets[i].type = AUTH_UNUSED; - buffer_free(&sockets[i].input); - buffer_free(&sockets[i].output); - buffer_free(&sockets[i].request); + close_socket(&sockets[i]); break; } buffer_consume(&sockets[i].output, len); @@ -858,12 +945,7 @@ after_select(fd_set *readset, fd_set *writeset) break; } while (1); if (len <= 0) { - shutdown(sockets[i].fd, SHUT_RDWR); - close(sockets[i].fd); - sockets[i].type = AUTH_UNUSED; - buffer_free(&sockets[i].input); - buffer_free(&sockets[i].output); - buffer_free(&sockets[i].request); + close_socket(&sockets[i]); break; } buffer_append(&sockets[i].input, buf, len); @@ -876,7 +958,7 @@ after_select(fd_set *readset, fd_set *writeset) } static void -cleanup_socket(void *p) +cleanup_socket(void) { if (socket_name[0]) unlink(socket_name); @@ -884,20 +966,22 @@ cleanup_socket(void *p) rmdir(socket_dir); } -static void +void cleanup_exit(int i) { - cleanup_socket(NULL); - exit(i); + cleanup_socket(); + _exit(i); } +/*ARGSUSED*/ static void cleanup_handler(int sig) { - cleanup_socket(NULL); + cleanup_socket(); _exit(2); } +/*ARGSUSED*/ static void check_parent_exists(int sig) { @@ -907,7 +991,7 @@ check_parent_exists(int sig) /* printf("Parent has died - Authentication agent exiting.\n"); */ cleanup_handler(sig); /* safe */ } - signal(SIGALRM, check_parent_exists); + mysignal(SIGALRM, check_parent_exists); alarm(10); errno = save_errno; } @@ -923,37 +1007,47 @@ usage(void) 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 sock, c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0, ch, nalloc; + 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 - pid_t pid; - char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; - char *agentsocket = NULL; extern int optind; - fd_set *readsetp = NULL, *writesetp = NULL; + 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 = get_progname(av[0]); + __progname = ssh_get_progname(av[0]); init_rng(); seed_rng(); -#ifdef __GNU_LIBRARY__ - while ((ch = getopt(ac, av, "+cdksa:")) != -1) { -#else /* __GNU_LIBRARY__ */ - while ((ch = getopt(ac, av, "cdksa:")) != -1) { -#endif /* __GNU_LIBRARY__ */ + while ((ch = getopt(ac, av, "cdksa:t:")) != -1) { switch (ch) { case 'c': if (s_flag) @@ -976,6 +1070,12 @@ main(int ac, char **av) case 'a': agentsocket = optarg; break; + case 't': + if ((lifetime = convtime(optarg)) == -1) { + fprintf(stderr, "Invalid lifetime\n"); + usage(); + } + break; default: usage(); } @@ -988,20 +1088,24 @@ main(int ac, char **av) if (ac == 0 && !c_flag && !s_flag) { shell = getenv("SHELL"); - if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0) + 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 = atoi(pidstr); - if (pid < 1) { - fprintf(stderr, "%s=\"%s\", which is not a good PID\n", - SSH_AGENTPID_ENV_NAME, pidstr); + 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) { @@ -1018,7 +1122,7 @@ main(int ac, char **av) if (agentsocket == NULL) { /* Create private directory for agent socket */ - strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); + strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir); if (mkdtemp(socket_dir) == NULL) { perror("mkdtemp: private socket dir"); exit(1); @@ -1038,25 +1142,21 @@ main(int ac, char **av) 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)); -#ifdef HAVE_CYGWIN prev_mask = umask(0177); -#endif - if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { + if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) { perror("bind"); -#ifdef HAVE_CYGWIN + *socket_name = '\0'; /* Don't unlink any existing file */ umask(prev_mask); -#endif cleanup_exit(1); } -#ifdef HAVE_CYGWIN umask(prev_mask); -#endif - if (listen(sock, 5) < 0) { + if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { perror("listen"); cleanup_exit(1); } @@ -1108,9 +1208,14 @@ main(int ac, char **av) } (void)chdir("/"); - close(0); - close(1); - close(2); + 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 */ @@ -1122,10 +1227,9 @@ main(int ac, char **av) #endif skip: - fatal_add_cleanup(cleanup_socket, NULL); new_socket(AUTH_SOCKET, sock); if (ac > 0) { - signal(SIGALRM, check_parent_exists); + mysignal(SIGALRM, check_parent_exists); alarm(10); } idtab_init();