/* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , 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" RCSID("$OpenBSD: authfd.c,v 1.66 2005/06/17 02:44:32 djm Exp $"); #include #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; break; } /* 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; break; } 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; }