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_log_auth(PR_LOG_NOTICE,
"USER %s (Login failed): 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);
pr_log_auth(PR_LOG_NOTICE,
"USER %s (Login failed): unsupported host key algorithm '%s' requested",
user, 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)) {
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): requested host "
"key is blacklisted", user);
*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) {
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): authentication "
"via '%s' host key failed", user, hostkey_algo);
*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);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): signature "
"verification of '%s' host key failed", user, hostkey_algo);
*send_userauth_fail = TRUE;
errno = EACCES;
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;
}
int proxy_session_setup_env(pool *p, const char *user, int flags) {
struct passwd *pw;
config_rec *c;
int i, res = 0, xerrno = 0;
const char *xferlog = NULL;
session.hide_password = TRUE;
/* Note: the given user name may not be known locally on the proxy; thus
* having pr_auth_getpwnam() returning NULL here is not an unexpected
* use case.
*/
pw = pr_auth_getpwnam(p, user);
if (pw != NULL) {
if (pw->pw_uid == PR_ROOT_UID) {
int root_login = FALSE;
pr_event_generate("mod_auth.root-login", NULL);
c = find_config(main_server->conf, CONF_PARAM, "RootLogin", FALSE);
if (c != NULL) {
root_login = *((int *) c->argv[0]);
}
if (root_login == FALSE) {
(void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
"root login attempted, denied by RootLogin configuration");
pr_log_auth(PR_LOG_NOTICE, "SECURITY VIOLATION: Root login attempted.");
return -1;
}
pr_log_auth(PR_LOG_WARNING, "ROOT proxy login successful");
}
res = pr_auth_is_valid_shell(main_server->conf, pw->pw_shell);
if (res == FALSE) {
(void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
"authentication for user '%s' failed: Invalid shell", user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): Invalid shell: '%s'",
user, pw->pw_shell);
errno = EPERM;
return -1;
}
res = pr_auth_banned_by_ftpusers(main_server->conf, pw->pw_name);
if (res == TRUE) {
(void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
"authentication for user '%s' failed: User in " PR_FTPUSERS_PATH, user);
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): User in "
PR_FTPUSERS_PATH, pw->pw_name);
errno = EPERM;
return -1;
}
session.user = pstrdup(p, pw->pw_name);
session.group = pstrdup(p, pr_auth_gid2name(p, pw->pw_gid));
session.login_uid = pw->pw_uid;
session.login_gid = pw->pw_gid;
} else {
session.user = pstrdup(session.pool, user);
/* XXX What should session.group, session.login_uid, session.login_gid
* be? Kept as is?
*/
}
if (session.gids == NULL &&
session.groups == NULL) {
res = pr_auth_getgroups(p, session.user, &session.gids, &session.groups);
if (res < 1 &&
errno != ENOENT) {
(void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
"no supplemental groups found for user '%s'", session.user);
}
}
if (flags & PROXY_SESSION_FL_CHECK_LOGIN_ACL) {
int login_acl;
login_acl = login_check_limits(main_server->conf, FALSE, TRUE, &i);
if (!login_acl) {
pr_log_auth(PR_LOG_NOTICE, "USER %s (Login failed): Limit configuration "
"denies login", user);
return -1;
}
}
/* XXX Will users want wtmp logging for a proxy login? */
session.wtmp_log = FALSE;
c = find_config(main_server->conf, CONF_PARAM, "TransferLog", FALSE);
if (c == NULL) {
xferlog = PR_XFERLOG_PATH;
} else {
xferlog = c->argv[0];
}
PRIVS_ROOT
if (strncasecmp(xferlog, "none", 5) == 0) {
xferlog_open(NULL);
} else {
xferlog_open(xferlog);
}
res = xerrno = 0;
if (pw != NULL) {
res = set_groups(p, pw->pw_gid, session.gids);
xerrno = errno;
}
PRIVS_RELINQUISH
if (res < 0) {
pr_log_pri(PR_LOG_WARNING, "unable to set process groups: %s",
strerror(xerrno));
}
session.disable_id_switching = TRUE;
session.proc_prefix = pstrdup(session.pool, session.c->remote_name);
session.sf_flags = 0;
pr_scoreboard_entry_update(session.pid,
PR_SCORE_USER, session.user,
PR_SCORE_CWD, pr_fs_getcwd(),
NULL);
if (session.group != NULL) {
session.group = pstrdup(session.pool, session.group);
}
if (session.groups != NULL) {
session.groups = copy_array_str(session.pool, session.groups);
}
proxy_sess_state |= PROXY_SESS_STATE_PROXY_AUTHENTICATED;
pr_timer_remove(PR_TIMER_LOGIN, ANY_MODULE);
return 0;
}
