| /* $OpenBSD: ssh-agent.c,v 1.24 1999/12/15 19:43:10 markus Exp $ */ |
| |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * Created: Wed Mar 29 03:46:59 1995 ylo |
| * The authentication agent program. |
| */ |
| |
| #include "includes.h" |
| RCSID("$OpenBSD: ssh-agent.c,v 1.24 1999/12/15 19:43:10 markus Exp $"); |
| |
| #include "ssh.h" |
| #include "rsa.h" |
| #include "authfd.h" |
| #include "buffer.h" |
| #include "bufaux.h" |
| #include "xmalloc.h" |
| #include "packet.h" |
| #include "getput.h" |
| #include "mpaux.h" |
| |
| #ifdef HAVE_OPENSSL |
| #include <openssl/md5.h> |
| #endif |
| #ifdef HAVE_SSL |
| #include <ssl/md5.h> |
| #endif |
| |
| typedef struct { |
| int fd; |
| enum { |
| AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION |
| } type; |
| Buffer input; |
| Buffer output; |
| } SocketEntry; |
| |
| unsigned int sockets_alloc = 0; |
| SocketEntry *sockets = NULL; |
| |
| typedef struct { |
| RSA *key; |
| char *comment; |
| } Identity; |
| |
| unsigned int num_identities = 0; |
| Identity *identities = NULL; |
| |
| int max_fd = 0; |
| |
| /* pid of shell == parent of agent */ |
| int parent_pid = -1; |
| |
| /* pathname and directory for AUTH_SOCKET */ |
| char socket_name[1024]; |
| char socket_dir[1024]; |
| |
| #ifdef HAVE___PROGNAME |
| extern char *__progname; |
| #else /* HAVE___PROGNAME */ |
| const char *__progname = "ssh-agent"; |
| #endif /* HAVE___PROGNAME */ |
| |
| void |
| process_request_identity(SocketEntry *e) |
| { |
| Buffer msg; |
| int i; |
| |
| buffer_init(&msg); |
| buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER); |
| buffer_put_int(&msg, num_identities); |
| for (i = 0; i < num_identities; i++) { |
| buffer_put_int(&msg, BN_num_bits(identities[i].key->n)); |
| buffer_put_bignum(&msg, identities[i].key->e); |
| buffer_put_bignum(&msg, identities[i].key->n); |
| buffer_put_string(&msg, identities[i].comment, |
| strlen(identities[i].comment)); |
| } |
| buffer_put_int(&e->output, buffer_len(&msg)); |
| buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg)); |
| buffer_free(&msg); |
| } |
| |
| void |
| process_authentication_challenge(SocketEntry *e) |
| { |
| int i, pub_bits, len; |
| BIGNUM *pub_e, *pub_n, *challenge; |
| Buffer msg; |
| MD5_CTX md; |
| unsigned char buf[32], mdbuf[16], session_id[16]; |
| unsigned int response_type; |
| |
| buffer_init(&msg); |
| pub_e = BN_new(); |
| pub_n = BN_new(); |
| challenge = BN_new(); |
| pub_bits = buffer_get_int(&e->input); |
| buffer_get_bignum(&e->input, pub_e); |
| buffer_get_bignum(&e->input, pub_n); |
| buffer_get_bignum(&e->input, challenge); |
| if (buffer_len(&e->input) == 0) { |
| /* Compatibility code for old servers. */ |
| memset(session_id, 0, 16); |
| response_type = 0; |
| } else { |
| /* New code. */ |
| buffer_get(&e->input, (char *) session_id, 16); |
| response_type = buffer_get_int(&e->input); |
| } |
| for (i = 0; i < num_identities; i++) |
| if (pub_bits == BN_num_bits(identities[i].key->n) && |
| BN_cmp(pub_e, identities[i].key->e) == 0 && |
| BN_cmp(pub_n, identities[i].key->n) == 0) { |
| /* Decrypt the challenge using the private key. */ |
| rsa_private_decrypt(challenge, challenge, identities[i].key); |
| |
| /* Compute the desired response. */ |
| switch (response_type) { |
| case 0:/* As of protocol 1.0 */ |
| /* This response type is no longer supported. */ |
| log("Compatibility with ssh protocol 1.0 no longer supported."); |
| buffer_put_char(&msg, SSH_AGENT_FAILURE); |
| goto send; |
| |
| case 1:/* As of protocol 1.1 */ |
| /* The response is MD5 of decrypted challenge plus session id. */ |
| len = BN_num_bytes(challenge); |
| |
| if (len <= 0 || len > 32) { |
| fatal("process_authentication_challenge: " |
| "bad challenge length %d", len); |
| } |
| 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); |
| break; |
| |
| default: |
| fatal("process_authentication_challenge: bad response_type %d", |
| response_type); |
| break; |
| } |
| |
| /* 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; |
| } |
| /* Unknown identity. 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)); |
| buffer_free(&msg); |
| BN_clear_free(pub_e); |
| BN_clear_free(pub_n); |
| BN_clear_free(challenge); |
| } |
| |
| void |
| process_remove_identity(SocketEntry *e) |
| { |
| unsigned int bits; |
| unsigned int i; |
| BIGNUM *dummy, *n; |
| |
| dummy = BN_new(); |
| n = BN_new(); |
| |
| /* Get the key from the packet. */ |
| bits = buffer_get_int(&e->input); |
| buffer_get_bignum(&e->input, dummy); |
| buffer_get_bignum(&e->input, n); |
| |
| if (bits != BN_num_bits(n)) |
| error("Warning: identity keysize mismatch: actual %d, announced %d", |
| BN_num_bits(n), bits); |
| |
| /* Check if we have the key. */ |
| for (i = 0; i < num_identities; i++) |
| if (BN_cmp(identities[i].key->n, n) == 0) { |
| /* |
| * 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 copy |
| * data from the last entry. |
| */ |
| RSA_free(identities[i].key); |
| xfree(identities[i].comment); |
| if (i < num_identities - 1) |
| identities[i] = identities[num_identities - 1]; |
| num_identities--; |
| BN_clear_free(dummy); |
| BN_clear_free(n); |
| |
| /* Send success. */ |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_SUCCESS); |
| return; |
| } |
| /* We did not have the key. */ |
| BN_clear(dummy); |
| BN_clear(n); |
| |
| /* Send failure. */ |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_FAILURE); |
| } |
| |
| /* |
| * Removes all identities from the agent. |
| */ |
| void |
| process_remove_all_identities(SocketEntry *e) |
| { |
| unsigned int i; |
| |
| /* Loop over all identities and clear the keys. */ |
| for (i = 0; i < num_identities; i++) { |
| RSA_free(identities[i].key); |
| xfree(identities[i].comment); |
| } |
| |
| /* Mark that there are no identities. */ |
| num_identities = 0; |
| |
| /* Send success. */ |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_SUCCESS); |
| return; |
| } |
| |
| /* |
| * Adds an identity to the agent. |
| */ |
| void |
| process_add_identity(SocketEntry *e) |
| { |
| RSA *k; |
| int i; |
| BIGNUM *aux; |
| BN_CTX *ctx; |
| |
| if (num_identities == 0) |
| identities = xmalloc(sizeof(Identity)); |
| else |
| identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity)); |
| |
| identities[num_identities].key = RSA_new(); |
| k = identities[num_identities].key; |
| buffer_get_int(&e->input); /* bits */ |
| k->n = BN_new(); |
| buffer_get_bignum(&e->input, k->n); |
| k->e = BN_new(); |
| buffer_get_bignum(&e->input, k->e); |
| k->d = BN_new(); |
| buffer_get_bignum(&e->input, k->d); |
| k->iqmp = BN_new(); |
| buffer_get_bignum(&e->input, k->iqmp); |
| /* SSH and SSL have p and q swapped */ |
| k->q = BN_new(); |
| buffer_get_bignum(&e->input, k->q); /* p */ |
| k->p = BN_new(); |
| buffer_get_bignum(&e->input, k->p); /* q */ |
| |
| /* Generate additional parameters */ |
| aux = BN_new(); |
| ctx = BN_CTX_new(); |
| |
| BN_sub(aux, k->q, BN_value_one()); |
| k->dmq1 = BN_new(); |
| BN_mod(k->dmq1, k->d, aux, ctx); |
| |
| BN_sub(aux, k->p, BN_value_one()); |
| k->dmp1 = BN_new(); |
| BN_mod(k->dmp1, k->d, aux, ctx); |
| |
| BN_clear_free(aux); |
| BN_CTX_free(ctx); |
| |
| identities[num_identities].comment = buffer_get_string(&e->input, NULL); |
| |
| /* Check if we already have the key. */ |
| for (i = 0; i < num_identities; i++) |
| if (BN_cmp(identities[i].key->n, k->n) == 0) { |
| /* |
| * We already have this key. Clear and free the new |
| * data and return success. |
| */ |
| RSA_free(k); |
| xfree(identities[num_identities].comment); |
| |
| /* Send success. */ |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_SUCCESS); |
| return; |
| } |
| /* Increment the number of identities. */ |
| num_identities++; |
| |
| /* Send a success message. */ |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_SUCCESS); |
| } |
| |
| void |
| process_message(SocketEntry *e) |
| { |
| unsigned int msg_len; |
| unsigned int type; |
| unsigned char *cp; |
| if (buffer_len(&e->input) < 5) |
| return; /* Incomplete message. */ |
| cp = (unsigned char *) buffer_ptr(&e->input); |
| msg_len = GET_32BIT(cp); |
| if (msg_len > 256 * 1024) { |
| shutdown(e->fd, SHUT_RDWR); |
| close(e->fd); |
| e->type = AUTH_UNUSED; |
| return; |
| } |
| if (buffer_len(&e->input) < msg_len + 4) |
| return; |
| buffer_consume(&e->input, 4); |
| type = buffer_get_char(&e->input); |
| |
| switch (type) { |
| case SSH_AGENTC_REQUEST_RSA_IDENTITIES: |
| process_request_identity(e); |
| break; |
| case SSH_AGENTC_RSA_CHALLENGE: |
| process_authentication_challenge(e); |
| break; |
| case SSH_AGENTC_ADD_RSA_IDENTITY: |
| process_add_identity(e); |
| break; |
| case SSH_AGENTC_REMOVE_RSA_IDENTITY: |
| process_remove_identity(e); |
| break; |
| case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: |
| process_remove_all_identities(e); |
| break; |
| default: |
| /* Unknown message. Respond with failure. */ |
| error("Unknown message %d", type); |
| buffer_clear(&e->input); |
| buffer_put_int(&e->output, 1); |
| buffer_put_char(&e->output, SSH_AGENT_FAILURE); |
| break; |
| } |
| } |
| |
| void |
| new_socket(int type, int fd) |
| { |
| unsigned int i, old_alloc; |
| if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) |
| error("fcntl O_NONBLOCK: %s", strerror(errno)); |
| |
| if (fd > max_fd) |
| max_fd = 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); |
| 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++) |
| sockets[i].type = AUTH_UNUSED; |
| sockets[old_alloc].type = type; |
| sockets[old_alloc].fd = fd; |
| buffer_init(&sockets[old_alloc].input); |
| buffer_init(&sockets[old_alloc].output); |
| } |
| |
| void |
| prepare_select(fd_set *readset, fd_set *writeset) |
| { |
| unsigned int i; |
| for (i = 0; i < sockets_alloc; i++) |
| switch (sockets[i].type) { |
| case AUTH_SOCKET: |
| case AUTH_CONNECTION: |
| FD_SET(sockets[i].fd, readset); |
| if (buffer_len(&sockets[i].output) > 0) |
| FD_SET(sockets[i].fd, writeset); |
| break; |
| case AUTH_UNUSED: |
| break; |
| default: |
| fatal("Unknown socket type %d", sockets[i].type); |
| break; |
| } |
| } |
| |
| void |
| after_select(fd_set *readset, fd_set *writeset) |
| { |
| unsigned int i; |
| int len, sock; |
| char buf[1024]; |
| struct sockaddr_un sunaddr; |
| |
| 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)) { |
| len = sizeof(sunaddr); |
| sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len); |
| if (sock < 0) { |
| perror("accept from AUTH_SOCKET"); |
| break; |
| } |
| new_socket(AUTH_CONNECTION, sock); |
| } |
| break; |
| case AUTH_CONNECTION: |
| if (buffer_len(&sockets[i].output) > 0 && |
| FD_ISSET(sockets[i].fd, writeset)) { |
| len = write(sockets[i].fd, buffer_ptr(&sockets[i].output), |
| buffer_len(&sockets[i].output)); |
| if (len <= 0) { |
| shutdown(sockets[i].fd, SHUT_RDWR); |
| close(sockets[i].fd); |
| sockets[i].type = AUTH_UNUSED; |
| break; |
| } |
| buffer_consume(&sockets[i].output, len); |
| } |
| if (FD_ISSET(sockets[i].fd, readset)) { |
| len = read(sockets[i].fd, buf, sizeof(buf)); |
| if (len <= 0) { |
| shutdown(sockets[i].fd, SHUT_RDWR); |
| close(sockets[i].fd); |
| sockets[i].type = AUTH_UNUSED; |
| break; |
| } |
| buffer_append(&sockets[i].input, buf, len); |
| process_message(&sockets[i]); |
| } |
| break; |
| default: |
| fatal("Unknown type %d", sockets[i].type); |
| } |
| } |
| |
| void |
| check_parent_exists(int sig) |
| { |
| if (kill(parent_pid, 0) < 0) { |
| /* printf("Parent has died - Authentication agent exiting.\n"); */ |
| exit(1); |
| } |
| signal(SIGALRM, check_parent_exists); |
| alarm(10); |
| } |
| |
| void |
| cleanup_socket(void) |
| { |
| remove(socket_name); |
| rmdir(socket_dir); |
| } |
| |
| void |
| cleanup_exit(int i) |
| { |
| cleanup_socket(); |
| exit(i); |
| } |
| |
| void |
| usage() |
| { |
| fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); |
| fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n", |
| __progname); |
| exit(1); |
| } |
| |
| int |
| main(int ac, char **av) |
| { |
| fd_set readset, writeset; |
| int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch; |
| struct sockaddr_un sunaddr; |
| pid_t pid; |
| char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid]; |
| |
| /* check if RSA support exists */ |
| if (rsa_alive() == 0) { |
| fprintf(stderr, |
| "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", |
| __progname); |
| exit(1); |
| } |
| while ((ch = getopt(ac, av, "cks")) != -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; |
| default: |
| usage(); |
| } |
| } |
| ac -= optind; |
| av += optind; |
| |
| if (ac > 0 && (c_flag || k_flag || s_flag)) |
| usage(); |
| |
| if (ac == 0 && !c_flag && !k_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) { /* XXX PID_MAX check too */ |
| 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 %d killed;\n", pid); |
| exit(0); |
| } |
| parent_pid = getpid(); |
| |
| /* Create private directory for agent socket */ |
| strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir); |
| if (mkdtemp(socket_dir) == NULL) { |
| perror("mkdtemp: private socket dir"); |
| exit(1); |
| } |
| snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir, |
| parent_pid); |
| |
| /* |
| * 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)); |
| if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { |
| perror("bind"); |
| cleanup_exit(1); |
| } |
| if (listen(sock, 5) < 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. |
| */ |
| pid = fork(); |
| if (pid == -1) { |
| perror("fork"); |
| exit(1); |
| } |
| if (pid != 0) { /* Parent - execute the given command. */ |
| close(sock); |
| snprintf(pidstrbuf, sizeof pidstrbuf, "%d", 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 %d;\n", pid); |
| exit(0); |
| } |
| setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1); |
| setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1); |
| execvp(av[0], av); |
| perror(av[0]); |
| exit(1); |
| } |
| close(0); |
| close(1); |
| close(2); |
| |
| if (setsid() == -1) { |
| perror("setsid"); |
| cleanup_exit(1); |
| } |
| if (atexit(cleanup_socket) < 0) { |
| perror("atexit"); |
| cleanup_exit(1); |
| } |
| new_socket(AUTH_SOCKET, sock); |
| if (ac > 0) { |
| signal(SIGALRM, check_parent_exists); |
| alarm(10); |
| } |
| signal(SIGHUP, cleanup_exit); |
| signal(SIGTERM, cleanup_exit); |
| signal(SIGINT, SIG_IGN); |
| signal(SIGPIPE, SIG_IGN); |
| while (1) { |
| FD_ZERO(&readset); |
| FD_ZERO(&writeset); |
| prepare_select(&readset, &writeset); |
| if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) { |
| if (errno == EINTR) |
| continue; |
| exit(1); |
| } |
| after_select(&readset, &writeset); |
| } |
| /* NOTREACHED */ |
| } |