| /* $OpenBSD: authfd.c,v 1.72 2006/03/25 13:17:01 djm Exp $ */ |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * Functions for connecting the local authentication agent. |
| * |
| * 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". |
| * |
| * SSH2 implementation, |
| * Copyright (c) 2000 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 <sys/types.h> |
| #include <sys/un.h> |
| |
| #include <openssl/evp.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 "cipher.h" |
| #include "kex.h" |
| #include "compat.h" |
| #include "log.h" |
| #include "atomicio.h" |
| |
| static int agent_present = 0; |
| |
| /* helper */ |
| int decode_reply(int type); |
| |
| /* macro to check for "agent failure" message */ |
| #define agent_failed(x) \ |
| ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \ |
| (x == SSH2_AGENT_FAILURE)) |
| |
| int |
| ssh_agent_present(void) |
| { |
| int authfd; |
| |
| if (agent_present) |
| return 1; |
| if ((authfd = ssh_get_authentication_socket()) == -1) |
| return 0; |
| else { |
| ssh_close_authentication_socket(authfd); |
| return 1; |
| } |
| } |
| |
| /* Returns the number of the authentication fd, or -1 if there is none. */ |
| |
| int |
| ssh_get_authentication_socket(void) |
| { |
| const char *authsocket; |
| int sock; |
| struct sockaddr_un sunaddr; |
| |
| authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); |
| if (!authsocket) |
| return -1; |
| |
| sunaddr.sun_family = AF_UNIX; |
| strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); |
| |
| sock = socket(AF_UNIX, SOCK_STREAM, 0); |
| if (sock < 0) |
| return -1; |
| |
| /* close on exec */ |
| if (fcntl(sock, F_SETFD, 1) == -1) { |
| close(sock); |
| return -1; |
| } |
| if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) { |
| close(sock); |
| return -1; |
| } |
| agent_present = 1; |
| return sock; |
| } |
| |
| static int |
| ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply) |
| { |
| u_int l, len; |
| char buf[1024]; |
| |
| /* Get the length of the message, and format it in the buffer. */ |
| len = buffer_len(request); |
| PUT_32BIT(buf, len); |
| |
| /* Send the length and then the packet to the agent. */ |
| if (atomicio(vwrite, auth->fd, buf, 4) != 4 || |
| atomicio(vwrite, auth->fd, buffer_ptr(request), |
| buffer_len(request)) != buffer_len(request)) { |
| error("Error writing to authentication socket."); |
| return 0; |
| } |
| /* |
| * Wait for response from the agent. First read the length of the |
| * response packet. |
| */ |
| if (atomicio(read, auth->fd, buf, 4) != 4) { |
| error("Error reading response length from authentication socket."); |
| return 0; |
| } |
| |
| /* Extract the length, and check it for sanity. */ |
| len = GET_32BIT(buf); |
| if (len > 256 * 1024) |
| fatal("Authentication response too long: %u", len); |
| |
| /* Read the rest of the response in to the buffer. */ |
| buffer_clear(reply); |
| while (len > 0) { |
| l = len; |
| if (l > sizeof(buf)) |
| l = sizeof(buf); |
| if (atomicio(read, auth->fd, buf, l) != l) { |
| error("Error reading response from authentication socket."); |
| return 0; |
| } |
| buffer_append(reply, buf, l); |
| len -= l; |
| } |
| return 1; |
| } |
| |
| /* |
| * Closes the agent socket if it should be closed (depends on how it was |
| * obtained). The argument must have been returned by |
| * ssh_get_authentication_socket(). |
| */ |
| |
| void |
| ssh_close_authentication_socket(int sock) |
| { |
| if (getenv(SSH_AUTHSOCKET_ENV_NAME)) |
| close(sock); |
| } |
| |
| /* |
| * Opens and connects a private socket for communication with the |
| * authentication agent. Returns the file descriptor (which must be |
| * shut down and closed by the caller when no longer needed). |
| * Returns NULL if an error occurred and the connection could not be |
| * opened. |
| */ |
| |
| AuthenticationConnection * |
| ssh_get_authentication_connection(void) |
| { |
| AuthenticationConnection *auth; |
| int sock; |
| |
| sock = ssh_get_authentication_socket(); |
| |
| /* |
| * Fail if we couldn't obtain a connection. This happens if we |
| * exited due to a timeout. |
| */ |
| if (sock < 0) |
| return NULL; |
| |
| auth = xmalloc(sizeof(*auth)); |
| auth->fd = sock; |
| buffer_init(&auth->identities); |
| auth->howmany = 0; |
| |
| return auth; |
| } |
| |
| /* |
| * Closes the connection to the authentication agent and frees any associated |
| * memory. |
| */ |
| |
| void |
| ssh_close_authentication_connection(AuthenticationConnection *auth) |
| { |
| buffer_free(&auth->identities); |
| close(auth->fd); |
| xfree(auth); |
| } |
| |
| /* Lock/unlock agent */ |
| int |
| ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password) |
| { |
| int type; |
| Buffer msg; |
| |
| buffer_init(&msg); |
| buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK); |
| buffer_put_cstring(&msg, password); |
| |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return 0; |
| } |
| type = buffer_get_char(&msg); |
| buffer_free(&msg); |
| return decode_reply(type); |
| } |
| |
| /* |
| * Returns the first authentication identity held by the agent. |
| */ |
| |
| int |
| ssh_get_num_identities(AuthenticationConnection *auth, int version) |
| { |
| int type, code1 = 0, code2 = 0; |
| Buffer request; |
| |
| switch (version) { |
| case 1: |
| code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES; |
| code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER; |
| break; |
| case 2: |
| code1 = SSH2_AGENTC_REQUEST_IDENTITIES; |
| code2 = SSH2_AGENT_IDENTITIES_ANSWER; |
| break; |
| default: |
| return 0; |
| } |
| |
| /* |
| * Send a message to the agent requesting for a list of the |
| * identities it can represent. |
| */ |
| buffer_init(&request); |
| buffer_put_char(&request, code1); |
| |
| buffer_clear(&auth->identities); |
| if (ssh_request_reply(auth, &request, &auth->identities) == 0) { |
| buffer_free(&request); |
| return 0; |
| } |
| buffer_free(&request); |
| |
| /* Get message type, and verify that we got a proper answer. */ |
| type = buffer_get_char(&auth->identities); |
| if (agent_failed(type)) { |
| return 0; |
| } else if (type != code2) { |
| fatal("Bad authentication reply message type: %d", type); |
| } |
| |
| /* Get the number of entries in the response and check it for sanity. */ |
| auth->howmany = buffer_get_int(&auth->identities); |
| if ((u_int)auth->howmany > 1024) |
| fatal("Too many identities in authentication reply: %d", |
| auth->howmany); |
| |
| return auth->howmany; |
| } |
| |
| Key * |
| ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version) |
| { |
| /* get number of identities and return the first entry (if any). */ |
| if (ssh_get_num_identities(auth, version) > 0) |
| return ssh_get_next_identity(auth, comment, version); |
| return NULL; |
| } |
| |
| Key * |
| ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version) |
| { |
| int keybits; |
| u_int bits; |
| u_char *blob; |
| u_int blen; |
| Key *key = NULL; |
| |
| /* Return failure if no more entries. */ |
| if (auth->howmany <= 0) |
| return NULL; |
| |
| /* |
| * Get the next entry from the packet. These will abort with a fatal |
| * error if the packet is too short or contains corrupt data. |
| */ |
| switch (version) { |
| case 1: |
| key = key_new(KEY_RSA1); |
| bits = buffer_get_int(&auth->identities); |
| buffer_get_bignum(&auth->identities, key->rsa->e); |
| buffer_get_bignum(&auth->identities, key->rsa->n); |
| *comment = buffer_get_string(&auth->identities, NULL); |
| keybits = BN_num_bits(key->rsa->n); |
| if (keybits < 0 || bits != (u_int)keybits) |
| logit("Warning: identity keysize mismatch: actual %d, announced %u", |
| BN_num_bits(key->rsa->n), bits); |
| break; |
| case 2: |
| blob = buffer_get_string(&auth->identities, &blen); |
| *comment = buffer_get_string(&auth->identities, NULL); |
| key = key_from_blob(blob, blen); |
| xfree(blob); |
| break; |
| default: |
| return NULL; |
| } |
| /* Decrement the number of remaining entries. */ |
| auth->howmany--; |
| return key; |
| } |
| |
| /* |
| * Generates a random challenge, sends it to the agent, and waits for |
| * response from the agent. Returns true (non-zero) if the agent gave the |
| * correct answer, zero otherwise. Response type selects the style of |
| * response desired, with 0 corresponding to protocol version 1.0 (no longer |
| * supported) and 1 corresponding to protocol version 1.1. |
| */ |
| |
| int |
| ssh_decrypt_challenge(AuthenticationConnection *auth, |
| Key* key, BIGNUM *challenge, |
| u_char session_id[16], |
| u_int response_type, |
| u_char response[16]) |
| { |
| Buffer buffer; |
| int success = 0; |
| int i; |
| int type; |
| |
| if (key->type != KEY_RSA1) |
| return 0; |
| if (response_type == 0) { |
| logit("Compatibility with ssh protocol version 1.0 no longer supported."); |
| return 0; |
| } |
| buffer_init(&buffer); |
| buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE); |
| buffer_put_int(&buffer, BN_num_bits(key->rsa->n)); |
| buffer_put_bignum(&buffer, key->rsa->e); |
| buffer_put_bignum(&buffer, key->rsa->n); |
| buffer_put_bignum(&buffer, challenge); |
| buffer_append(&buffer, session_id, 16); |
| buffer_put_int(&buffer, response_type); |
| |
| if (ssh_request_reply(auth, &buffer, &buffer) == 0) { |
| buffer_free(&buffer); |
| return 0; |
| } |
| type = buffer_get_char(&buffer); |
| |
| if (agent_failed(type)) { |
| logit("Agent admitted failure to authenticate using the key."); |
| } else if (type != SSH_AGENT_RSA_RESPONSE) { |
| fatal("Bad authentication response: %d", type); |
| } else { |
| success = 1; |
| /* |
| * Get the response from the packet. This will abort with a |
| * fatal error if the packet is corrupt. |
| */ |
| for (i = 0; i < 16; i++) |
| response[i] = buffer_get_char(&buffer); |
| } |
| buffer_free(&buffer); |
| return success; |
| } |
| |
| /* ask agent to sign data, returns -1 on error, 0 on success */ |
| int |
| ssh_agent_sign(AuthenticationConnection *auth, |
| Key *key, |
| u_char **sigp, u_int *lenp, |
| u_char *data, u_int datalen) |
| { |
| extern int datafellows; |
| Buffer msg; |
| u_char *blob; |
| u_int blen; |
| int type, flags = 0; |
| int ret = -1; |
| |
| if (key_to_blob(key, &blob, &blen) == 0) |
| return -1; |
| |
| if (datafellows & SSH_BUG_SIGBLOB) |
| flags = SSH_AGENT_OLD_SIGNATURE; |
| |
| buffer_init(&msg); |
| buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST); |
| buffer_put_string(&msg, blob, blen); |
| buffer_put_string(&msg, data, datalen); |
| buffer_put_int(&msg, flags); |
| xfree(blob); |
| |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return -1; |
| } |
| type = buffer_get_char(&msg); |
| if (agent_failed(type)) { |
| logit("Agent admitted failure to sign using the key."); |
| } else if (type != SSH2_AGENT_SIGN_RESPONSE) { |
| fatal("Bad authentication response: %d", type); |
| } else { |
| ret = 0; |
| *sigp = buffer_get_string(&msg, lenp); |
| } |
| buffer_free(&msg); |
| return ret; |
| } |
| |
| /* Encode key for a message to the agent. */ |
| |
| static void |
| ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment) |
| { |
| buffer_put_int(b, BN_num_bits(key->n)); |
| buffer_put_bignum(b, key->n); |
| buffer_put_bignum(b, key->e); |
| buffer_put_bignum(b, key->d); |
| /* To keep within the protocol: p < q for ssh. in SSL p > q */ |
| buffer_put_bignum(b, key->iqmp); /* ssh key->u */ |
| buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */ |
| buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */ |
| buffer_put_cstring(b, comment); |
| } |
| |
| static void |
| ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment) |
| { |
| buffer_put_cstring(b, key_ssh_name(key)); |
| switch (key->type) { |
| case KEY_RSA: |
| buffer_put_bignum2(b, key->rsa->n); |
| buffer_put_bignum2(b, key->rsa->e); |
| buffer_put_bignum2(b, key->rsa->d); |
| buffer_put_bignum2(b, key->rsa->iqmp); |
| buffer_put_bignum2(b, key->rsa->p); |
| buffer_put_bignum2(b, key->rsa->q); |
| break; |
| case KEY_DSA: |
| buffer_put_bignum2(b, key->dsa->p); |
| buffer_put_bignum2(b, key->dsa->q); |
| buffer_put_bignum2(b, key->dsa->g); |
| buffer_put_bignum2(b, key->dsa->pub_key); |
| buffer_put_bignum2(b, key->dsa->priv_key); |
| break; |
| } |
| buffer_put_cstring(b, comment); |
| } |
| |
| /* |
| * Adds an identity to the authentication server. This call is not meant to |
| * be used by normal applications. |
| */ |
| |
| int |
| ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key, |
| const char *comment, u_int life, u_int confirm) |
| { |
| Buffer msg; |
| int type, constrained = (life || confirm); |
| |
| buffer_init(&msg); |
| |
| switch (key->type) { |
| case KEY_RSA1: |
| type = constrained ? |
| SSH_AGENTC_ADD_RSA_ID_CONSTRAINED : |
| SSH_AGENTC_ADD_RSA_IDENTITY; |
| buffer_put_char(&msg, type); |
| ssh_encode_identity_rsa1(&msg, key->rsa, comment); |
| break; |
| case KEY_RSA: |
| case KEY_DSA: |
| type = constrained ? |
| SSH2_AGENTC_ADD_ID_CONSTRAINED : |
| SSH2_AGENTC_ADD_IDENTITY; |
| buffer_put_char(&msg, type); |
| ssh_encode_identity_ssh2(&msg, key, comment); |
| break; |
| default: |
| buffer_free(&msg); |
| return 0; |
| } |
| if (constrained) { |
| if (life != 0) { |
| buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME); |
| buffer_put_int(&msg, life); |
| } |
| if (confirm != 0) |
| buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM); |
| } |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return 0; |
| } |
| type = buffer_get_char(&msg); |
| buffer_free(&msg); |
| return decode_reply(type); |
| } |
| |
| int |
| ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment) |
| { |
| return ssh_add_identity_constrained(auth, key, comment, 0, 0); |
| } |
| |
| /* |
| * Removes an identity from the authentication server. This call is not |
| * meant to be used by normal applications. |
| */ |
| |
| int |
| ssh_remove_identity(AuthenticationConnection *auth, Key *key) |
| { |
| Buffer msg; |
| int type; |
| u_char *blob; |
| u_int blen; |
| |
| buffer_init(&msg); |
| |
| if (key->type == KEY_RSA1) { |
| buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY); |
| buffer_put_int(&msg, BN_num_bits(key->rsa->n)); |
| buffer_put_bignum(&msg, key->rsa->e); |
| buffer_put_bignum(&msg, key->rsa->n); |
| } else if (key->type == KEY_DSA || key->type == KEY_RSA) { |
| key_to_blob(key, &blob, &blen); |
| buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY); |
| buffer_put_string(&msg, blob, blen); |
| xfree(blob); |
| } else { |
| buffer_free(&msg); |
| return 0; |
| } |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return 0; |
| } |
| type = buffer_get_char(&msg); |
| buffer_free(&msg); |
| return decode_reply(type); |
| } |
| |
| int |
| ssh_update_card(AuthenticationConnection *auth, int add, |
| const char *reader_id, const char *pin, u_int life, u_int confirm) |
| { |
| Buffer msg; |
| int type, constrained = (life || confirm); |
| |
| if (add) { |
| type = constrained ? |
| SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED : |
| SSH_AGENTC_ADD_SMARTCARD_KEY; |
| } else |
| type = SSH_AGENTC_REMOVE_SMARTCARD_KEY; |
| |
| buffer_init(&msg); |
| buffer_put_char(&msg, type); |
| buffer_put_cstring(&msg, reader_id); |
| buffer_put_cstring(&msg, pin); |
| |
| if (constrained) { |
| if (life != 0) { |
| buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME); |
| buffer_put_int(&msg, life); |
| } |
| if (confirm != 0) |
| buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM); |
| } |
| |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return 0; |
| } |
| type = buffer_get_char(&msg); |
| buffer_free(&msg); |
| return decode_reply(type); |
| } |
| |
| /* |
| * Removes all identities from the agent. This call is not meant to be used |
| * by normal applications. |
| */ |
| |
| int |
| ssh_remove_all_identities(AuthenticationConnection *auth, int version) |
| { |
| Buffer msg; |
| int type; |
| int code = (version==1) ? |
| SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES : |
| SSH2_AGENTC_REMOVE_ALL_IDENTITIES; |
| |
| buffer_init(&msg); |
| buffer_put_char(&msg, code); |
| |
| if (ssh_request_reply(auth, &msg, &msg) == 0) { |
| buffer_free(&msg); |
| return 0; |
| } |
| type = buffer_get_char(&msg); |
| buffer_free(&msg); |
| return decode_reply(type); |
| } |
| |
| int |
| decode_reply(int type) |
| { |
| switch (type) { |
| case SSH_AGENT_FAILURE: |
| case SSH_COM_AGENT2_FAILURE: |
| case SSH2_AGENT_FAILURE: |
| logit("SSH_AGENT_FAILURE"); |
| return 0; |
| case SSH_AGENT_SUCCESS: |
| return 1; |
| default: |
| fatal("Bad response from authentication agent: %d", type); |
| } |
| /* NOTREACHED */ |
| return 0; |
| } |