/* $OpenBSD: authfd.c,v 1.94 2015/01/14 20:05:27 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 <fcntl.h>
#include <stdlib.h>
#include <signal.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "xmalloc.h"
#include "ssh.h"
#include "rsa.h"
#include "sshbuf.h"
#include "sshkey.h"
#include "authfd.h"
#include "cipher.h"
#include "compat.h"
#include "log.h"
#include "atomicio.h"
#include "misc.h"
#include "ssherr.h"
#define MAX_AGENT_IDENTITIES 2048 /* Max keys in agent reply */
#define MAX_AGENT_REPLY_LEN (256 * 1024) /* Max bytes in agent reply */
/* macro to check for "agent failure" message */
#define agent_failed(x) \
((x == SSH_AGENT_FAILURE) || \
(x == SSH_COM_AGENT2_FAILURE) || \
(x == SSH2_AGENT_FAILURE))
/* Convert success/failure response from agent to a err.h status */
static int
decode_reply(u_char type)
{
if (agent_failed(type))
return SSH_ERR_AGENT_FAILURE;
else if (type == SSH_AGENT_SUCCESS)
return 0;
else
return SSH_ERR_INVALID_FORMAT;
}
/* Returns the number of the authentication fd, or -1 if there is none. */
int
ssh_get_authentication_socket(int *fdp)
{
const char *authsocket;
int sock, oerrno;
struct sockaddr_un sunaddr;
if (fdp != NULL)
*fdp = -1;
authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
if (!authsocket)
return SSH_ERR_AGENT_NOT_PRESENT;
memset(&sunaddr, 0, sizeof(sunaddr));
sunaddr.sun_family = AF_UNIX;
strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
return SSH_ERR_SYSTEM_ERROR;
/* close on exec */
if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 ||
connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
oerrno = errno;
close(sock);
errno = oerrno;
return SSH_ERR_SYSTEM_ERROR;
}
if (fdp != NULL)
*fdp = sock;
else
close(sock);
return 0;
}
/* Communicate with agent: send request and read reply */
static int
ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
{
int r;
size_t l, len;
char buf[1024];
/* Get the length of the message, and format it in the buffer. */
len = sshbuf_len(request);
put_u32(buf, len);
/* Send the length and then the packet to the agent. */
if (atomicio(vwrite, sock, buf, 4) != 4 ||
atomicio(vwrite, sock, (u_char *)sshbuf_ptr(request),
sshbuf_len(request)) != sshbuf_len(request))
return SSH_ERR_AGENT_COMMUNICATION;
/*
* Wait for response from the agent. First read the length of the
* response packet.
*/
if (atomicio(read, sock, buf, 4) != 4)
return SSH_ERR_AGENT_COMMUNICATION;
/* Extract the length, and check it for sanity. */
len = get_u32(buf);
if (len > MAX_AGENT_REPLY_LEN)
return SSH_ERR_INVALID_FORMAT;
/* Read the rest of the response in to the buffer. */
sshbuf_reset(reply);
while (len > 0) {
l = len;
if (l > sizeof(buf))
l = sizeof(buf);
if (atomicio(read, sock, buf, l) != l)
return SSH_ERR_AGENT_COMMUNICATION;
if ((r = sshbuf_put(reply, buf, l)) != 0)
return r;
len -= l;
}
return 0;
}
/*
* 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);
}
/* Lock/unlock agent */
int
ssh_lock_agent(int sock, int lock, const char *password)
{
int r;
u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK;
struct sshbuf *msg;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_u8(msg, type)) != 0 ||
(r = sshbuf_put_cstring(msg, password)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
r = decode_reply(type);
out:
sshbuf_free(msg);
return r;
}
#ifdef WITH_SSH1
static int
deserialise_identity1(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
{
struct sshkey *key;
int r, keybits;
u_int32_t bits;
char *comment = NULL;
if ((key = sshkey_new(KEY_RSA1)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_get_u32(ids, &bits)) != 0 ||
(r = sshbuf_get_bignum1(ids, key->rsa->e)) != 0 ||
(r = sshbuf_get_bignum1(ids, key->rsa->n)) != 0 ||
(r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
goto out;
keybits = BN_num_bits(key->rsa->n);
/* XXX previously we just warned here. I think we should be strict */
if (keybits < 0 || bits != (u_int)keybits) {
r = SSH_ERR_KEY_BITS_MISMATCH;
goto out;
}
if (keyp != NULL) {
*keyp = key;
key = NULL;
}
if (commentp != NULL) {
*commentp = comment;
comment = NULL;
}
r = 0;
out:
sshkey_free(key);
free(comment);
return r;
}
#endif
static int
deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
{
int r;
char *comment = NULL;
const u_char *blob;
size_t blen;
if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 ||
(r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
goto out;
if ((r = sshkey_from_blob(blob, blen, keyp)) != 0)
goto out;
if (commentp != NULL) {
*commentp = comment;
comment = NULL;
}
r = 0;
out:
free(comment);
return r;
}
/*
* Fetch list of identities held by the agent.
*/
int
ssh_fetch_identitylist(int sock, int version, struct ssh_identitylist **idlp)
{
u_char type, code1 = 0, code2 = 0;
u_int32_t num, i;
struct sshbuf *msg;
struct ssh_identitylist *idl = NULL;
int r;
/* Determine request and expected response types */
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 SSH_ERR_INVALID_ARGUMENT;
}
/*
* Send a message to the agent requesting for a list of the
* identities it can represent.
*/
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_u8(msg, code1)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
/* Get message type, and verify that we got a proper answer. */
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
if (agent_failed(type)) {
r = SSH_ERR_AGENT_FAILURE;
goto out;
} else if (type != code2) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
/* Get the number of entries in the response and check it for sanity. */
if ((r = sshbuf_get_u32(msg, &num)) != 0)
goto out;
if (num > MAX_AGENT_IDENTITIES) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if (num == 0) {
r = SSH_ERR_AGENT_NO_IDENTITIES;
goto out;
}
/* Deserialise the response into a list of keys/comments */
if ((idl = calloc(1, sizeof(*idl))) == NULL ||
(idl->keys = calloc(num, sizeof(*idl->keys))) == NULL ||
(idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
for (i = 0; i < num;) {
switch (version) {
case 1:
#ifdef WITH_SSH1
if ((r = deserialise_identity1(msg,
&(idl->keys[i]), &(idl->comments[i]))) != 0)
goto out;
#endif
break;
case 2:
if ((r = deserialise_identity2(msg,
&(idl->keys[i]), &(idl->comments[i]))) != 0) {
if (r == SSH_ERR_KEY_TYPE_UNKNOWN) {
/* Gracefully skip unknown key types */
num--;
continue;
} else
goto out;
}
break;
}
i++;
}
idl->nkeys = num;
*idlp = idl;
idl = NULL;
r = 0;
out:
sshbuf_free(msg);
if (idl != NULL)
ssh_free_identitylist(idl);
return r;
}
void
ssh_free_identitylist(struct ssh_identitylist *idl)
{
size_t i;
if (idl == NULL)
return;
for (i = 0; i < idl->nkeys; i++) {
if (idl->keys != NULL)
sshkey_free(idl->keys[i]);
if (idl->comments != NULL)
free(idl->comments[i]);
}
free(idl);
}
/*
* Sends a challenge (typically from a server via ssh(1)) to the agent,
* and waits for a response from the agent.
* Returns true (non-zero) if the agent gave the correct answer, zero
* otherwise.
*/
#ifdef WITH_SSH1
int
ssh_decrypt_challenge(int sock, struct sshkey* key, BIGNUM *challenge,
u_char session_id[16], u_char response[16])
{
struct sshbuf *msg;
int r;
u_char type;
if (key->type != KEY_RSA1)
return SSH_ERR_INVALID_ARGUMENT;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_u8(msg, SSH_AGENTC_RSA_CHALLENGE)) != 0 ||
(r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 ||
(r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 ||
(r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0 ||
(r = sshbuf_put_bignum1(msg, challenge)) != 0 ||
(r = sshbuf_put(msg, session_id, 16)) != 0 ||
(r = sshbuf_put_u32(msg, 1)) != 0) /* Response type for proto 1.1 */
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
if (agent_failed(type)) {
r = SSH_ERR_AGENT_FAILURE;
goto out;
} else if (type != SSH_AGENT_RSA_RESPONSE) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if ((r = sshbuf_get(msg, response, 16)) != 0)
goto out;
r = 0;
out:
sshbuf_free(msg);
return r;
}
#endif
/* ask agent to sign data, returns err.h code on error, 0 on success */
int
ssh_agent_sign(int sock, struct sshkey *key,
u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, u_int compat)
{
struct sshbuf *msg;
u_char *blob = NULL, type;
size_t blen = 0, len = 0;
u_int flags = 0;
int r = SSH_ERR_INTERNAL_ERROR;
if (sigp != NULL)
*sigp = NULL;
if (lenp != NULL)
*lenp = 0;
if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE)
return SSH_ERR_INVALID_ARGUMENT;
if (compat & SSH_BUG_SIGBLOB)
flags |= SSH_AGENT_OLD_SIGNATURE;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
goto out;
if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
(r = sshbuf_put_string(msg, blob, blen)) != 0 ||
(r = sshbuf_put_string(msg, data, datalen)) != 0 ||
(r = sshbuf_put_u32(msg, flags)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg) != 0))
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
if (agent_failed(type)) {
r = SSH_ERR_AGENT_FAILURE;
goto out;
} else if (type != SSH2_AGENT_SIGN_RESPONSE) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if ((r = sshbuf_get_string(msg, sigp, &len)) != 0)
goto out;
*lenp = len;
r = 0;
out:
if (blob != NULL) {
explicit_bzero(blob, blen);
free(blob);
}
sshbuf_free(msg);
return r;
}
/* Encode key for a message to the agent. */
#ifdef WITH_SSH1
static int
ssh_encode_identity_rsa1(struct sshbuf *b, RSA *key, const char *comment)
{
int r;
/* To keep within the protocol: p < q for ssh. in SSL p > q */
if ((r = sshbuf_put_u32(b, BN_num_bits(key->n))) != 0 ||
(r = sshbuf_put_bignum1(b, key->n)) != 0 ||
(r = sshbuf_put_bignum1(b, key->e)) != 0 ||
(r = sshbuf_put_bignum1(b, key->d)) != 0 ||
(r = sshbuf_put_bignum1(b, key->iqmp)) != 0 ||
(r = sshbuf_put_bignum1(b, key->q)) != 0 ||
(r = sshbuf_put_bignum1(b, key->p)) != 0 ||
(r = sshbuf_put_cstring(b, comment)) != 0)
return r;
return 0;
}
#endif
static int
ssh_encode_identity_ssh2(struct sshbuf *b, struct sshkey *key,
const char *comment)
{
int r;
if ((r = sshkey_private_serialize(key, b)) != 0 ||
(r = sshbuf_put_cstring(b, comment)) != 0)
return r;
return 0;
}
static int
encode_constraints(struct sshbuf *m, u_int life, u_int confirm)
{
int r;
if (life != 0) {
if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 ||
(r = sshbuf_put_u32(m, life)) != 0)
goto out;
}
if (confirm != 0) {
if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
goto out;
}
r = 0;
out:
return r;
}
/*
* Adds an identity to the authentication server.
* This call is intended only for use by ssh-add(1) and like applications.
*/
int
ssh_add_identity_constrained(int sock, struct sshkey *key, const char *comment,
u_int life, u_int confirm)
{
struct sshbuf *msg;
int r, constrained = (life || confirm);
u_char type;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
switch (key->type) {
#ifdef WITH_SSH1
case KEY_RSA1:
type = constrained ?
SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
SSH_AGENTC_ADD_RSA_IDENTITY;
if ((r = sshbuf_put_u8(msg, type)) != 0 ||
(r = ssh_encode_identity_rsa1(msg, key->rsa, comment)) != 0)
goto out;
break;
#endif
#ifdef WITH_OPENSSL
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:
#endif
case KEY_ED25519:
case KEY_ED25519_CERT:
type = constrained ?
SSH2_AGENTC_ADD_ID_CONSTRAINED :
SSH2_AGENTC_ADD_IDENTITY;
if ((r = sshbuf_put_u8(msg, type)) != 0 ||
(r = ssh_encode_identity_ssh2(msg, key, comment)) != 0)
goto out;
break;
default:
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
if (constrained &&
(r = encode_constraints(msg, life, confirm)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
r = decode_reply(type);
out:
sshbuf_free(msg);
return r;
}
/*
* Removes an identity from the authentication server.
* This call is intended only for use by ssh-add(1) and like applications.
*/
int
ssh_remove_identity(int sock, struct sshkey *key)
{
struct sshbuf *msg;
int r;
u_char type, *blob = NULL;
size_t blen;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
#ifdef WITH_SSH1
if (key->type == KEY_RSA1) {
if ((r = sshbuf_put_u8(msg,
SSH_AGENTC_REMOVE_RSA_IDENTITY)) != 0 ||
(r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 ||
(r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 ||
(r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0)
goto out;
} else
#endif
if (key->type != KEY_UNSPEC) {
if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
goto out;
if ((r = sshbuf_put_u8(msg,
SSH2_AGENTC_REMOVE_IDENTITY)) != 0 ||
(r = sshbuf_put_string(msg, blob, blen)) != 0)
goto out;
} else {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
r = decode_reply(type);
out:
if (blob != NULL) {
explicit_bzero(blob, blen);
free(blob);
}
sshbuf_free(msg);
return r;
}
/*
* Add/remove an token-based identity from the authentication server.
* This call is intended only for use by ssh-add(1) and like applications.
*/
int
ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
u_int life, u_int confirm)
{
struct sshbuf *msg;
int r, constrained = (life || confirm);
u_char type;
if (add) {
type = constrained ?
SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
SSH_AGENTC_ADD_SMARTCARD_KEY;
} else
type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_u8(msg, type)) != 0 ||
(r = sshbuf_put_cstring(msg, reader_id)) != 0 ||
(r = sshbuf_put_cstring(msg, pin)) != 0)
goto out;
if (constrained &&
(r = encode_constraints(msg, life, confirm)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
r = decode_reply(type);
out:
sshbuf_free(msg);
return r;
}
/*
* Removes all identities from the agent.
* This call is intended only for use by ssh-add(1) and like applications.
*/
int
ssh_remove_all_identities(int sock, int version)
{
struct sshbuf *msg;
u_char type = (version == 1) ?
SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
int r;
if ((msg = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_u8(msg, type)) != 0)
goto out;
if ((r = ssh_request_reply(sock, msg, msg)) != 0)
goto out;
if ((r = sshbuf_get_u8(msg, &type)) != 0)
goto out;
r = decode_reply(type);
out:
sshbuf_free(msg);
return r;
}