diff options
author | Damien Miller <djm@mindrot.org> | 1999-10-27 13:42:43 +1000 |
---|---|---|
committer | Damien Miller <djm@mindrot.org> | 1999-10-27 13:42:43 +1000 |
commit | d4a8b7e34dd619a4debf9a206c81db26d1402ea6 (patch) | |
tree | a47d770a2f790f40d18b0982d4e55fa7cfb1fa3b /ssh-agent.c |
Initial revision
Diffstat (limited to 'ssh-agent.c')
-rw-r--r-- | ssh-agent.c | 572 |
1 files changed, 572 insertions, 0 deletions
diff --git a/ssh-agent.c b/ssh-agent.c new file mode 100644 index 00000000..19165b8f --- /dev/null +++ b/ssh-agent.c @@ -0,0 +1,572 @@ +/* + +ssh-agent.c + +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("$Id: ssh-agent.c,v 1.1 1999/10/27 03:42:45 damien 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" + +#include <openssl/md5.h> + +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]; + +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); + assert(len <= 32 && 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); + + /* 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); +} + +int +main(int ac, char **av) +{ + fd_set readset, writeset; + int sock; + struct sockaddr_un sunaddr; + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + extern char *__progname; + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); + } + + if (ac < 2) + { + fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION); + fprintf(stderr, "Usage: %s command\n", av[0]); + exit(1); + } + + 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); + + /* Fork, and have the parent execute the command. The child continues as + the authentication agent. */ + if (fork() != 0) + { /* Parent - execute the given command. */ + setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1); + execvp(av[1], av + 1); + perror(av[1]); + exit(1); + } + + if (atexit(cleanup_socket) < 0) { + perror("atexit"); + cleanup_socket(); + exit(1); + } + + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + { + perror("socket"); + 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"); + exit(1); + } + if (listen(sock, 5) < 0) + { + perror("listen"); + exit(1); + } + new_socket(AUTH_SOCKET, sock); + signal(SIGALRM, check_parent_exists); + alarm(10); + + signal(SIGINT, 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; + perror("select"); + exit(1); + } + after_select(&readset, &writeset); + } + /*NOTREACHED*/ +} |