diff options
Diffstat (limited to 'crypto/openssh/authfd.c')
-rw-r--r-- | crypto/openssh/authfd.c | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/crypto/openssh/authfd.c b/crypto/openssh/authfd.c new file mode 100644 index 0000000..f963690 --- /dev/null +++ b/crypto/openssh/authfd.c @@ -0,0 +1,657 @@ +/* $OpenBSD: authfd.c,v 1.91 2013/12/29 04:29:25 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 <sys/socket.h> + +#include <openssl/evp.h> +#include <openssl/crypto.h> + +#include <fcntl.h> +#include <stdlib.h> +#include <signal.h> +#include <stdarg.h> +#include <string.h> +#include <unistd.h> + +#include "xmalloc.h" +#include "ssh.h" +#include "rsa.h" +#include "buffer.h" +#include "key.h" +#include "authfd.h" +#include "cipher.h" +#include "kex.h" +#include "compat.h" +#include "log.h" +#include "atomicio.h" +#include "misc.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; + + bzero(&sunaddr, sizeof(sunaddr)); + 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, FD_CLOEXEC) == -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_u32(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_u32(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 = xcalloc(1, 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); + free(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); + free(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] = (u_char)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); + free(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) +{ + key_private_serialize(key, b); + 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_RSA_CERT: + case KEY_RSA_CERT_V00: + case KEY_DSA: + case KEY_DSA_CERT: + case KEY_DSA_CERT_V00: + case KEY_ECDSA: + case KEY_ECDSA_CERT: + case KEY_ED25519: + case KEY_ED25519_CERT: + 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); +} + +/* + * 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_UNSPEC) { + key_to_blob(key, &blob, &blen); + buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY); + buffer_put_string(&msg, blob, blen); + free(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; +} |