int sftp_auth_hostbased(struct ssh2_packet *pkt, cmd_rec *pass_cmd,
const char *orig_user, const char *user, const char *service,
unsigned char **buf, uint32_t *buflen, int *send_userauth_fail) {
struct passwd *pw;
char *hostkey_algo, *host_fqdn, *host_user, *host_user_utf8;
const char *fp = NULL;
unsigned char *hostkey_data, *signature_data;
unsigned char *buf2, *ptr2;
const unsigned char *id;
uint32_t buflen2, bufsz2, hostkey_datalen, id_len, signature_len;
enum sftp_key_type_e pubkey_type;
if (pr_cmd_dispatch_phase(pass_cmd, PRE_CMD, 0) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication request for user '%s' blocked by '%s' handler",
orig_user, (char *) pass_cmd->argv[0]);
pr_cmd_dispatch_phase(pass_cmd, POST_CMD_ERR, 0);
pr_cmd_dispatch_phase(pass_cmd, LOG_CMD_ERR, 0);
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
hostkey_algo = sftp_msg_read_string(pkt->pool, buf, buflen);
if (hostkey_algo == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"missing required host key algorithm, rejecting request");
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
hostkey_datalen = sftp_msg_read_int(pkt->pool, buf, buflen);
hostkey_data = sftp_msg_read_data(pkt->pool, buf, buflen, hostkey_datalen);
host_fqdn = sftp_msg_read_string(pkt->pool, buf, buflen);
host_user_utf8 = sftp_msg_read_string(pkt->pool, buf, buflen);
host_user = sftp_utf8_decode_str(pkt->pool, host_user_utf8);
signature_len = sftp_msg_read_int(pkt->pool, buf, buflen);
signature_data = sftp_msg_read_data(pkt->pool, buf, buflen, signature_len);
pr_trace_msg(trace_channel, 9,
"client sent '%s' host key, FQDN %s, and remote user '%s'",
hostkey_algo, host_fqdn, host_user);
if (strncmp(hostkey_algo, "ssh-rsa", 8) == 0) {
pubkey_type = SFTP_KEY_RSA;
} else if (strncmp(hostkey_algo, "ssh-dss", 8) == 0) {
pubkey_type = SFTP_KEY_DSA;
#ifdef PR_USE_OPENSSL_ECC
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_256;
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_384;
} else if (strncmp(hostkey_algo, "ecdsa-sha2-nistp256", 20) == 0) {
pubkey_type = SFTP_KEY_ECDSA_521;
#endif /* PR_USE_OPENSSL_ECC */
/* XXX Need to support X509v3 certs here */
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unsupported host key algorithm '%s' requested, rejecting request",
hostkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
if (sftp_keys_verify_pubkey_type(pkt->pool, hostkey_data, hostkey_datalen,
pubkey_type) != TRUE) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unable to verify that given host key matches given '%s' algorithm",
hostkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
#ifdef OPENSSL_FIPS
if (FIPS_mode()) {
fp = sftp_keys_get_fingerprint(pkt->pool, hostkey_data, hostkey_datalen,
SFTP_KEYS_FP_DIGEST_SHA1);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key SHA1 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key SHA1 fingerprint: %s", strerror(errno));
}
} else {
#endif /* OPENSSL_FIPS */
fp = sftp_keys_get_fingerprint(pkt->pool, hostkey_data, hostkey_datalen,
SFTP_KEYS_FP_DIGEST_MD5);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key MD5 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key MD5 fingerprint: %s", strerror(errno));
}
#ifdef OPENSSL_FIPS
}
#endif /* OPENSSL_FIPS */
pw = pr_auth_getpwnam(pkt->pool, user);
if (pw == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"no account for user '%s' found", user);
pr_log_auth(PR_LOG_NOTICE,
"USER %s: no such user found from %s [%s] to %s:%d", user,
session.c->remote_name, pr_netaddr_get_ipstr(session.c->remote_addr),
pr_netaddr_get_ipstr(session.c->local_addr), session.c->local_port);
*send_userauth_fail = TRUE;
errno = ENOENT;
return 0;
}
/* XXX Should we check the given FQDN here against the client's actual
* DNS name and/or IP address? Or leave that up to the keystore's
* verify_host_key() function?
*/
if (sftp_blacklist_reject_key(pkt->pool, hostkey_data, hostkey_datalen)) {
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
/* The client signed the request as well; we need to authenticate the
* host with the given key now. If that succeeds, we use the signature to
* verify the request. And if that succeeds, then we're done authenticating.
*/
if (sftp_keystore_verify_host_key(pkt->pool, user, host_fqdn, host_user,
hostkey_data, hostkey_datalen) < 0) {
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
/* Make sure the signature matches as well. */
id_len = sftp_session_get_id(&id);
/* XXX Is this buffer large enough? Too large? */
bufsz2 = buflen2 = 2048;
ptr2 = buf2 = sftp_msg_getbuf(pkt->pool, bufsz2);
sftp_msg_write_data(&buf2, &buflen2, id, id_len, TRUE);
sftp_msg_write_byte(&buf2, &buflen2, SFTP_SSH2_MSG_USER_AUTH_REQUEST);
sftp_msg_write_string(&buf2, &buflen2, orig_user);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_SERVICE_IN_HOST_SIG)) {
sftp_msg_write_string(&buf2, &buflen2, service);
} else {
sftp_msg_write_string(&buf2, &buflen2, "ssh-userauth");
}
sftp_msg_write_string(&buf2, &buflen2, "hostbased");
sftp_msg_write_string(&buf2, &buflen2, hostkey_algo);
sftp_msg_write_data(&buf2, &buflen2, hostkey_data, hostkey_datalen, TRUE);
sftp_msg_write_string(&buf2, &buflen2, host_fqdn);
sftp_msg_write_string(&buf2, &buflen2, host_user_utf8);
if (sftp_keys_verify_signed_data(pkt->pool, hostkey_algo, hostkey_data,
hostkey_datalen, signature_data, signature_len, (unsigned char *) ptr2,
(bufsz2 - buflen2)) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"failed to verify '%s' signature on hostbased auth request for "
"user '%s', host %s", hostkey_algo, orig_user, host_fqdn);
*send_userauth_fail = TRUE;
return 0;
}
/* Make sure the user is authorized to login. Normally this is checked
* as part of the password verification process, but in the case of
* hostbased authentication, there is no password to verify.
*/
if (pr_auth_authorize(pkt->pool, user) != PR_AUTH_OK) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication for user '%s' failed: User not authorized", user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): User not authorized "
"for login", user);
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
return 1;
}
const unsigned char *sftp_agent_sign_data(pool *p, const char *agent_path,
const unsigned char *key_data, uint32_t key_datalen,
const unsigned char *data, uint32_t datalen, uint32_t *sig_datalen) {
int fd;
unsigned char *buf, *req, *resp, *sig_data;
uint32_t buflen, flags, reqlen, reqsz, resplen;
char resp_status;
fd = agent_connect(agent_path);
if (fd < 0) {
return NULL;
}
/* XXX When to set flags to OLD_SIGNATURE? */
flags = 0;
/* Write out the request for signing the given data. */
reqsz = buflen = 1 + key_datalen + 4 + datalen + 4 + 4;
req = buf = palloc(p, reqsz);
sftp_msg_write_byte(&buf, &buflen, SFTP_SSH_AGENT_REQ_SIGN_DATA);
sftp_msg_write_data(&buf, &buflen, key_data, key_datalen, TRUE);
sftp_msg_write_data(&buf, &buflen, data, datalen, TRUE);
sftp_msg_write_int(&buf, &buflen, flags);
reqlen = reqsz - buflen;
resp = agent_request(p, fd, agent_path, req, reqlen, &resplen);
if (resp == NULL) {
int xerrno = errno;
(void) close(fd);
errno = xerrno;
return NULL;
}
(void) close(fd);
/* Read the response from the agent. */
resp_status = sftp_msg_read_byte(p, &resp, &resplen);
if (agent_failure(resp_status) == TRUE) {
pr_trace_msg(trace_channel, 5,
"SSH agent at '%s' indicated failure (%d) for data signing request",
agent_path, resp_status);
errno = EPERM;
return NULL;
}
if (resp_status != SFTP_SSH_AGENT_RESP_SIGN_DATA) {
pr_trace_msg(trace_channel, 5,
"unknown response type %d from SSH agent at '%s'", resp_status,
agent_path);
errno = EACCES;
return NULL;
}
*sig_datalen = sftp_msg_read_int(p, &resp, &resplen);
sig_data = sftp_msg_read_data(p, &resp, &resplen, *sig_datalen);
return sig_data;
}
int sftp_auth_publickey(struct ssh2_packet *pkt, cmd_rec *pass_cmd,
const char *orig_user, const char *user, const char *service, char **buf,
uint32_t *buflen, int *send_userauth_fail) {
int have_signature, pubkey_type;
char *pubkey_algo = NULL, *pubkey_data;
const char *fp = NULL;
uint32_t pubkey_len;
struct passwd *pw;
if (pr_cmd_dispatch_phase(pass_cmd, PRE_CMD, 0) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication request for user '%s' blocked by '%s' handler",
orig_user, pass_cmd->argv[0]);
pr_cmd_dispatch_phase(pass_cmd, POST_CMD_ERR, 0);
pr_cmd_dispatch_phase(pass_cmd, LOG_CMD_ERR, 0);
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
have_signature = sftp_msg_read_bool(pkt->pool, buf, buflen);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_HAVE_PUBKEY_ALGO)) {
pubkey_algo = sftp_msg_read_string(pkt->pool, buf, buflen);
}
pubkey_len = sftp_msg_read_int(pkt->pool, buf, buflen);
pubkey_data = sftp_msg_read_data(pkt->pool, buf, buflen, pubkey_len);
if (pubkey_algo == NULL) {
/* The client did not send the string identifying the public key algorithm.
* Thus we need to extract the algorithm string from the public key data.
*/
pubkey_algo = sftp_msg_read_string(pkt->pool, &pubkey_data, &pubkey_len);
}
pr_trace_msg(trace_channel, 9, "client sent '%s' public key %s",
pubkey_algo, have_signature ? "with signature" : "without signature");
if (strncmp(pubkey_algo, "ssh-rsa", 8) == 0) {
pubkey_type = EVP_PKEY_RSA;
} else if (strncmp(pubkey_algo, "ssh-dss", 8) == 0) {
pubkey_type = EVP_PKEY_DSA;
/* XXX This is where we would add support for X509 public keys, e.g.:
*
* x509v3-ssh-dss
* x509v3-ssh-rsa
* x509v3-sign (older)
*
*/
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unsupported public key algorithm '%s' requested, rejecting request",
pubkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
if (sftp_keys_verify_pubkey_type(pkt->pool, pubkey_data, pubkey_len,
pubkey_type) != TRUE) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"unable to verify that given public key matches given '%s' algorithm",
pubkey_algo);
*send_userauth_fail = TRUE;
errno = EINVAL;
return 0;
}
#ifdef OPENSSL_FIPS
if (FIPS_mode()) {
fp = sftp_keys_get_fingerprint(pkt->pool, pubkey_data, pubkey_len,
SFTP_KEYS_FP_DIGEST_SHA1);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key SHA1 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key SHA1 fingerprint: %s", strerror(errno));
}
} else {
#endif /* OPENSSL_FIPS */
fp = sftp_keys_get_fingerprint(pkt->pool, pubkey_data, pubkey_len,
SFTP_KEYS_FP_DIGEST_MD5);
if (fp != NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"public key MD5 fingerprint: %s", fp);
} else {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"error obtaining public key MD5 fingerprint: %s", strerror(errno));
}
#ifdef OPENSSL_FIPS
}
#endif /* OPENSSL_FIPS */
pw = pr_auth_getpwnam(pkt->pool, user);
if (pw == NULL) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"no account for user '%s' found", user);
pr_log_auth(PR_LOG_NOTICE,
"USER %s: no such user found from %s [%s] to %s:%d", user,
session.c->remote_name, pr_netaddr_get_ipstr(session.c->remote_addr),
pr_netaddr_get_ipstr(session.c->local_addr), session.c->local_port);
*send_userauth_fail = TRUE;
errno = ENOENT;
return 0;
}
if (!have_signature) {
/* We don't perform the actual authentication just yet; we need to
* let the client know that the pubkey algorithms are acceptable.
*/
if (send_pubkey_ok(pubkey_algo, pubkey_data, pubkey_len) < 0) {
return -1;
}
return 0;
} else {
const unsigned char *id;
char *buf2, *ptr2, *signature_data;
uint32_t buflen2, bufsz2, id_len, signature_len;
/* XXX This should become a more generic "is this key data
* usable/acceptable?" check (and take the pubkey_type parameter), so that
* that is where we would check the validity/usability of an X509v3 cert
* (if a cert), or if the key is on the blacklist (if a key).
*/
if (sftp_blacklist_reject_key(pkt->pool, pubkey_data, pubkey_len)) {
*send_userauth_fail = TRUE;
errno = EPERM;
return 0;
}
signature_len = sftp_msg_read_int(pkt->pool, buf, buflen);
signature_data = sftp_msg_read_data(pkt->pool, buf, buflen, signature_len);
/* The client signed the request as well; we need to authenticate the
* user with the given pubkey now. If that succeeds, we use the
* signature to verify the request. And if that succeeds, then we're
* done authenticating.
*/
/* XXX Need to pass the pubkey_type here as well, so that the
* verification routines can handle different databases of keys/certs.
*
* For X509v3 certs, we will want a way to enforce/restrict which
* user names can be used with the provided cert. Perhaps a database
* mapping cert fingerprints to user names/UIDs? Configurable callback
* check (HOOK?), for modules to enforce.
*/
if (sftp_keystore_verify_user_key(pkt->pool, user, pubkey_data,
pubkey_len) < 0) {
*send_userauth_fail = TRUE;
return 0;
}
/* Make sure the signature matches as well. */
id_len = sftp_session_get_id(&id);
/* Make sure to allocate a buffer large enough to hold the publickey
* signature and data we want to send back.
*/
bufsz2 = buflen2 = pubkey_len + 1024;
ptr2 = buf2 = sftp_msg_getbuf(pkt->pool, bufsz2);
sftp_msg_write_data(&buf2, &buflen2, (char *) id, id_len, TRUE);
sftp_msg_write_byte(&buf2, &buflen2, SFTP_SSH2_MSG_USER_AUTH_REQUEST);
sftp_msg_write_string(&buf2, &buflen2, orig_user);
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_SERVICE_IN_PUBKEY_SIG)) {
sftp_msg_write_string(&buf2, &buflen2, service);
} else {
sftp_msg_write_string(&buf2, &buflen2, "ssh-userauth");
}
if (sftp_interop_supports_feature(SFTP_SSH2_FEAT_HAVE_PUBKEY_ALGO)) {
sftp_msg_write_string(&buf2, &buflen2, "publickey");
sftp_msg_write_bool(&buf2, &buflen2, TRUE);
sftp_msg_write_string(&buf2, &buflen2, pubkey_algo);
} else {
sftp_msg_write_bool(&buf2, &buflen2, TRUE);
}
sftp_msg_write_data(&buf2, &buflen2, pubkey_data, pubkey_len, TRUE);
if (sftp_keys_verify_signed_data(pkt->pool, pubkey_algo, pubkey_data,
pubkey_len, signature_data, signature_len, (unsigned char *) ptr2,
(bufsz2 - buflen2)) < 0) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"failed to verify '%s' signature on public key auth request for "
"user '%s'", pubkey_algo, orig_user);
*send_userauth_fail = TRUE;
return 0;
}
}
/* Make sure the user is authorized to login. Normally this is checked
* as part of the password verification process, but in the case of
* publickey authentication, there is no password to verify.
*/
if (pr_auth_authorize(pkt->pool, user) != PR_AUTH_OK) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"authentication for user '%s' failed: User not authorized", user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): User not authorized "
"for login", user);
*send_userauth_fail = TRUE;
errno = EACCES;
return 0;
}
return 1;
}
int sftp_agent_get_keys(pool *p, const char *agent_path,
array_header *key_list) {
register unsigned int i;
int fd;
unsigned char *buf, *req, *resp;
uint32_t buflen, key_count, reqlen, reqsz, resplen;
char resp_status;
fd = agent_connect(agent_path);
if (fd < 0) {
return -1;
}
/* Write out the request for the identities (i.e. the public keys). */
reqsz = buflen = 64;
req = buf = palloc(p, reqsz);
sftp_msg_write_byte(&buf, &buflen, SFTP_SSH_AGENT_REQ_IDS);
reqlen = reqsz - buflen;
resp = agent_request(p, fd, agent_path, req, reqlen, &resplen);
if (resp == NULL) {
int xerrno = errno;
(void) close(fd);
errno = xerrno;
return -1;
}
(void) close(fd);
/* Read the response from the agent. */
resp_status = sftp_msg_read_byte(p, &resp, &resplen);
if (agent_failure(resp_status) == TRUE) {
pr_trace_msg(trace_channel, 5,
"SSH agent at '%s' indicated failure (%d) for identities request",
agent_path, resp_status);
errno = EPERM;
return -1;
}
if (resp_status != SFTP_SSH_AGENT_RESP_IDS) {
pr_trace_msg(trace_channel, 5,
"unknown response type %d from SSH agent at '%s'", resp_status,
agent_path);
errno = EACCES;
return -1;
}
key_count = sftp_msg_read_int(p, &resp, &resplen);
if (key_count > AGENT_MAX_KEYS) {
(void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
"SSH agent at '%s' returned too many keys (%lu, max %lu)", agent_path,
(unsigned long) key_count, (unsigned long) AGENT_MAX_KEYS);
errno = EPERM;
return -1;
}
for (i = 0; i < key_count; i++) {
unsigned char *key_data;
uint32_t key_datalen;
char *key_comment;
struct agent_key *key;
key_datalen = sftp_msg_read_int(p, &resp, &resplen);
key_data = sftp_msg_read_data(p, &resp, &resplen, key_datalen);
key_comment = sftp_msg_read_string(p, &resp, &resplen);
if (key_comment != NULL) {
pr_trace_msg(trace_channel, 9,
"SSH agent at '%s' provided comment '%s' for key #%u", agent_path,
key_comment, (i + 1));
}
key = pcalloc(p, sizeof(struct agent_key));
key->key_data = key_data;
key->key_datalen = key_datalen;
key->agent_path = pstrdup(p, agent_path);
*((struct agent_key **) push_array(key_list)) = key;
}
pr_trace_msg(trace_channel, 9, "SSH agent at '%s' provided %lu %s",
agent_path, (unsigned long) key_count, key_count != 1 ? "keys" : "key");
return 0;
}
