#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <pwd.h>
#ifdef HAVE_LOGIN_H
#include <login.h>
#endif
#ifdef USE_SHADOW
#include <shadow.h>
#endif
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <netdb.h>
#include <time.h>
#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "sshbuf.h"
#include "misc.h"
#include "servconf.h"
#include "sshkey.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "uidswap.h"
#include "packet.h"
#include "loginrec.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "authfile.h"
#include "monitor_wrap.h"
#include "ssherr.h"
#include "channels.h"
#include "blocklist_client.h"
extern ServerOptions options;
extern struct include_list includes;
extern struct sshbuf *loginmsg;
extern struct passwd *privsep_pw;
extern struct sshauthopt *auth_opts;
static struct sshbuf *auth_debug;
int
allowed_user(struct ssh *ssh, struct passwd * pw)
{
struct stat st;
const char *hostname = NULL, *ipaddr = NULL;
u_int i;
int r;
if (!pw || !pw->pw_name)
return 0;
if (!options.use_pam && platform_locked_account(pw)) {
logit("User %.100s not allowed because account is locked",
pw->pw_name);
return 0;
}
if (options.chroot_directory == NULL ||
strcasecmp(options.chroot_directory, "none") == 0) {
char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
_PATH_BSHELL : pw->pw_shell);
if (stat(shell, &st) == -1) {
logit("User %.100s not allowed because shell %.100s "
"does not exist", pw->pw_name, shell);
free(shell);
return 0;
}
if (S_ISREG(st.st_mode) == 0 ||
(st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
logit("User %.100s not allowed because shell %.100s "
"is not executable", pw->pw_name, shell);
free(shell);
return 0;
}
free(shell);
}
if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
options.num_deny_groups > 0 || options.num_allow_groups > 0) {
hostname = auth_get_canonical_hostname(ssh, options.use_dns);
ipaddr = ssh_remote_ipaddr(ssh);
}
if (options.num_deny_users > 0) {
for (i = 0; i < options.num_deny_users; i++) {
r = match_user(pw->pw_name, hostname, ipaddr,
options.deny_users[i]);
if (r < 0) {
fatal("Invalid DenyUsers pattern \"%.100s\"",
options.deny_users[i]);
} else if (r != 0) {
logit("User %.100s from %.100s not allowed "
"because listed in DenyUsers",
pw->pw_name, hostname);
return 0;
}
}
}
if (options.num_allow_users > 0) {
for (i = 0; i < options.num_allow_users; i++) {
r = match_user(pw->pw_name, hostname, ipaddr,
options.allow_users[i]);
if (r < 0) {
fatal("Invalid AllowUsers pattern \"%.100s\"",
options.allow_users[i]);
} else if (r == 1)
break;
}
if (i >= options.num_allow_users) {
logit("User %.100s from %.100s not allowed because "
"not listed in AllowUsers", pw->pw_name, hostname);
return 0;
}
}
if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
logit("User %.100s from %.100s not allowed because "
"not in any group", pw->pw_name, hostname);
return 0;
}
if (options.num_deny_groups > 0)
if (ga_match(options.deny_groups,
options.num_deny_groups)) {
ga_free();
logit("User %.100s from %.100s not allowed "
"because a group is listed in DenyGroups",
pw->pw_name, hostname);
return 0;
}
if (options.num_allow_groups > 0)
if (!ga_match(options.allow_groups,
options.num_allow_groups)) {
ga_free();
logit("User %.100s from %.100s not allowed "
"because none of user's groups are listed "
"in AllowGroups", pw->pw_name, hostname);
return 0;
}
ga_free();
}
#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
if (!sys_auth_allowed_user(pw, loginmsg))
return 0;
#endif
return 1;
}
static char *
format_method_key(Authctxt *authctxt)
{
const struct sshkey *key = authctxt->auth_method_key;
const char *methinfo = authctxt->auth_method_info;
char *fp, *cafp, *ret = NULL;
if (key == NULL)
return NULL;
if (sshkey_is_cert(key)) {
fp = sshkey_fingerprint(key,
options.fingerprint_hash, SSH_FP_DEFAULT);
cafp = sshkey_fingerprint(key->cert->signature_key,
options.fingerprint_hash, SSH_FP_DEFAULT);
xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s",
sshkey_type(key), fp == NULL ? "(null)" : fp,
key->cert->key_id,
(unsigned long long)key->cert->serial,
sshkey_type(key->cert->signature_key),
cafp == NULL ? "(null)" : cafp,
methinfo == NULL ? "" : ", ",
methinfo == NULL ? "" : methinfo);
free(fp);
free(cafp);
} else {
fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT);
xasprintf(&ret, "%s %s%s%s", sshkey_type(key),
fp == NULL ? "(null)" : fp,
methinfo == NULL ? "" : ", ",
methinfo == NULL ? "" : methinfo);
free(fp);
}
return ret;
}
void
auth_log(struct ssh *ssh, int authenticated, int partial,
const char *method, const char *submethod)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
int level = SYSLOG_LEVEL_VERBOSE;
const char *authmsg;
char *extra = NULL;
if (!mm_is_monitor() && !authctxt->postponed)
return;
if (authenticated == 1 ||
!authctxt->valid ||
authctxt->failures >= options.max_authtries / 2 ||
strcmp(method, "password") == 0)
level = SYSLOG_LEVEL_INFO;
if (authctxt->postponed)
authmsg = "Postponed";
else if (partial)
authmsg = "Partial";
else {
authmsg = authenticated ? "Accepted" : "Failed";
if (authenticated)
BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_OK,
"Authenticated");
}
if ((extra = format_method_key(authctxt)) == NULL) {
if (authctxt->auth_method_info != NULL)
extra = xstrdup(authctxt->auth_method_info);
}
do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s",
authmsg,
method,
submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
authctxt->valid ? "" : "invalid user ",
authctxt->user,
ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh),
extra != NULL ? ": " : "",
extra != NULL ? extra : "");
free(extra);
#if defined(CUSTOM_FAILED_LOGIN) || defined(SSH_AUDIT_EVENTS)
if (authenticated == 0 && !(authctxt->postponed || partial)) {
# ifdef CUSTOM_FAILED_LOGIN
if (strcmp(method, "password") == 0 ||
strncmp(method, "keyboard-interactive", 20) == 0 ||
strcmp(method, "challenge-response") == 0)
record_failed_login(ssh, authctxt->user,
auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
# endif
# ifdef SSH_AUDIT_EVENTS
audit_event(ssh, audit_classify_auth(method));
# endif
}
#endif
#if defined(CUSTOM_FAILED_LOGIN) && defined(WITH_AIXAUTHENTICATE)
if (authenticated)
sys_auth_record_login(authctxt->user,
auth_get_canonical_hostname(ssh, options.use_dns), "ssh",
loginmsg);
#endif
}
void
auth_maxtries_exceeded(struct ssh *ssh)
{
Authctxt *authctxt = (Authctxt *)ssh->authctxt;
BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL, "Maximum attempts exceeded");
error("maximum authentication attempts exceeded for "
"%s%.100s from %.200s port %d ssh2",
authctxt->valid ? "" : "invalid user ",
authctxt->user,
ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh));
ssh_packet_disconnect(ssh, "Too many authentication failures");
}
int
auth_root_allowed(struct ssh *ssh, const char *method)
{
switch (options.permit_root_login) {
case PERMIT_YES:
return 1;
case PERMIT_NO_PASSWD:
if (strcmp(method, "publickey") == 0 ||
strcmp(method, "hostbased") == 0 ||
strcmp(method, "gssapi-with-mic") == 0)
return 1;
break;
case PERMIT_FORCED_ONLY:
if (auth_opts->force_command != NULL) {
logit("Root login accepted for forced command.");
return 1;
}
break;
}
logit("ROOT LOGIN REFUSED FROM %.200s port %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
return 0;
}
char *
expand_authorized_keys(const char *filename, struct passwd *pw)
{
char *file, uidstr[32], ret[PATH_MAX];
int i;
snprintf(uidstr, sizeof(uidstr), "%llu",
(unsigned long long)pw->pw_uid);
file = percent_expand(filename, "h", pw->pw_dir,
"u", pw->pw_name, "U", uidstr, (char *)NULL);
if (path_absolute(file))
return (file);
i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
if (i < 0 || (size_t)i >= sizeof(ret))
fatal("expand_authorized_keys: path too long");
free(file);
return (xstrdup(ret));
}
char *
authorized_principals_file(struct passwd *pw)
{
if (options.authorized_principals_file == NULL)
return NULL;
return expand_authorized_keys(options.authorized_principals_file, pw);
}
HostStatus
check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
const char *sysfile, const char *userfile)
{
char *user_hostfile;
struct stat st;
HostStatus host_status;
struct hostkeys *hostkeys;
const struct hostkey_entry *found;
hostkeys = init_hostkeys();
load_hostkeys(hostkeys, host, sysfile, 0);
if (userfile != NULL) {
user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
if (options.strict_modes &&
(stat(user_hostfile, &st) == 0) &&
((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
(st.st_mode & 022) != 0)) {
logit("Authentication refused for %.100s: "
"bad owner or modes for %.200s",
pw->pw_name, user_hostfile);
auth_debug_add("Ignored %.200s: bad ownership or modes",
user_hostfile);
} else {
temporarily_use_uid(pw);
load_hostkeys(hostkeys, host, user_hostfile, 0);
restore_uid();
}
free(user_hostfile);
}
host_status = check_key_in_hostkeys(hostkeys, key, &found);
if (host_status == HOST_REVOKED)
error("WARNING: revoked key for %s attempted authentication",
host);
else if (host_status == HOST_OK)
debug_f("key for %s found at %s:%ld",
found->host, found->file, found->line);
else
debug_f("key for host %s not found", host);
free_hostkeys(hostkeys);
return host_status;
}
struct passwd *
getpwnamallow(struct ssh *ssh, const char *user)
{
#ifdef HAVE_LOGIN_CAP
extern login_cap_t *lc;
#ifdef HAVE_AUTH_HOSTOK
const char *from_host, *from_ip;
#endif
#ifdef BSD_AUTH
auth_session_t *as;
#endif
#endif
struct passwd *pw;
struct connection_info *ci;
u_int i;
ci = server_get_connection_info(ssh, 1, options.use_dns);
ci->user = user;
ci->user_invalid = getpwnam(user) == NULL;
parse_server_match_config(&options, &includes, ci);
log_change_level(options.log_level);
log_verbose_reset();
for (i = 0; i < options.num_log_verbose; i++)
log_verbose_add(options.log_verbose[i]);
server_process_permitopen(ssh);
#if defined(_AIX) && defined(HAVE_SETAUTHDB)
aix_setauthdb(user);
#endif
pw = getpwnam(user);
#if defined(_AIX) && defined(HAVE_SETAUTHDB)
aix_restoreauthdb();
#endif
if (pw == NULL) {
BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL, "Invalid user");
logit("Invalid user %.100s from %.100s port %d",
user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
#ifdef CUSTOM_FAILED_LOGIN
record_failed_login(ssh, user,
auth_get_canonical_hostname(ssh, options.use_dns), "ssh");
#endif
#ifdef SSH_AUDIT_EVENTS
audit_event(ssh, SSH_INVALID_USER);
#endif
return (NULL);
}
if (!allowed_user(ssh, pw))
return (NULL);
#ifdef HAVE_LOGIN_CAP
if ((lc = login_getpwclass(pw)) == NULL) {
debug("unable to get login class: %s", user);
return (NULL);
}
#ifdef HAVE_AUTH_HOSTOK
from_host = auth_get_canonical_hostname(ssh, options.use_dns);
from_ip = ssh_remote_ipaddr(ssh);
if (!auth_hostok(lc, from_host, from_ip)) {
debug("Denied connection for %.200s from %.200s [%.200s].",
pw->pw_name, from_host, from_ip);
return (NULL);
}
#endif
#ifdef HAVE_AUTH_TIMEOK
if (!auth_timeok(lc, time(NULL))) {
debug("LOGIN %.200s REFUSED (TIME)", pw->pw_name);
return (NULL);
}
#endif
#ifdef BSD_AUTH
if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
debug("Approval failure for %s", user);
pw = NULL;
}
if (as != NULL)
auth_close(as);
#endif
#endif
if (pw != NULL)
return (pwcopy(pw));
return (NULL);
}
int
auth_key_is_revoked(struct sshkey *key)
{
char *fp = NULL;
int r;
if (options.revoked_keys_file == NULL)
return 0;
if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
error_fr(r, "fingerprint key");
goto out;
}
r = sshkey_check_revoked(key, options.revoked_keys_file);
switch (r) {
case 0:
break;
case SSH_ERR_KEY_REVOKED:
error("Authentication key %s %s revoked by file %s",
sshkey_type(key), fp, options.revoked_keys_file);
goto out;
default:
error_r(r, "Error checking authentication key %s %s in "
"revoked keys file %s", sshkey_type(key), fp,
options.revoked_keys_file);
goto out;
}
r = 0;
out:
free(fp);
return r == 0 ? 0 : 1;
}
void
auth_debug_add(const char *fmt,...)
{
char buf[1024];
va_list args;
int r;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
debug3("%s", buf);
if (auth_debug != NULL)
if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0)
fatal_fr(r, "sshbuf_put_cstring");
}
void
auth_debug_send(struct ssh *ssh)
{
char *msg;
int r;
if (auth_debug == NULL)
return;
while (sshbuf_len(auth_debug) != 0) {
if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0)
fatal_fr(r, "sshbuf_get_cstring");
ssh_packet_send_debug(ssh, "%s", msg);
free(msg);
}
}
void
auth_debug_reset(void)
{
if (auth_debug != NULL)
sshbuf_reset(auth_debug);
else if ((auth_debug = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
}
struct passwd *
fakepw(void)
{
static int done = 0;
static struct passwd fake;
const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz0123456789";
char *cp;
if (done)
return (&fake);
memset(&fake, 0, sizeof(fake));
fake.pw_name = "NOUSER";
fake.pw_passwd = xstrdup("$2a$10$"
"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++)
*cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)];
#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
fake.pw_gecos = "NOUSER";
#endif
fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
fake.pw_class = "";
#endif
fake.pw_dir = "/nonexist";
fake.pw_shell = "/nonexist";
done = 1;
return (&fake);
}
const char *
auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
{
static char *dnsname;
if (!use_dns)
return ssh_remote_ipaddr(ssh);
if (dnsname != NULL)
return dnsname;
dnsname = ssh_remote_hostname(ssh);
return dnsname;
}
void
auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote)
{
int do_env = options.permit_user_env && opts->nenv > 0;
int do_permitopen = opts->npermitopen > 0 &&
(options.allow_tcp_forwarding & FORWARD_LOCAL) != 0;
int do_permitlisten = opts->npermitlisten > 0 &&
(options.allow_tcp_forwarding & FORWARD_REMOTE) != 0;
size_t i;
char msg[1024], buf[64];
snprintf(buf, sizeof(buf), "%d", opts->force_tun_device);
snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
opts->permit_agent_forwarding_flag ? " agent-forwarding" : "",
opts->force_command == NULL ? "" : " command",
do_env ? " environment" : "",
opts->valid_before == 0 ? "" : "expires",
opts->no_require_user_presence ? " no-touch-required" : "",
do_permitopen ? " permitopen" : "",
do_permitlisten ? " permitlisten" : "",
opts->permit_port_forwarding_flag ? " port-forwarding" : "",
opts->cert_principals == NULL ? "" : " principals",
opts->permit_pty_flag ? " pty" : "",
opts->require_verify ? " uv" : "",
opts->force_tun_device == -1 ? "" : " tun=",
opts->force_tun_device == -1 ? "" : buf,
opts->permit_user_rc ? " user-rc" : "",
opts->permit_x11_forwarding_flag ? " x11-forwarding" : "");
debug("%s: %s", loc, msg);
if (do_remote)
auth_debug_add("%s: %s", loc, msg);
if (options.permit_user_env) {
for (i = 0; i < opts->nenv; i++) {
debug("%s: environment: %s", loc, opts->env[i]);
if (do_remote) {
auth_debug_add("%s: environment: %s",
loc, opts->env[i]);
}
}
}
if (opts->valid_before != 0) {
format_absolute_time(opts->valid_before, buf, sizeof(buf));
debug("%s: expires at %s", loc, buf);
}
if (opts->cert_principals != NULL) {
debug("%s: authorized principals: \"%s\"",
loc, opts->cert_principals);
}
if (opts->force_command != NULL)
debug("%s: forced command: \"%s\"", loc, opts->force_command);
if (do_permitopen) {
for (i = 0; i < opts->npermitopen; i++) {
debug("%s: permitted open: %s",
loc, opts->permitopen[i]);
}
}
if (do_permitlisten) {
for (i = 0; i < opts->npermitlisten; i++) {
debug("%s: permitted listen: %s",
loc, opts->permitlisten[i]);
}
}
}
int
auth_activate_options(struct ssh *ssh, struct sshauthopt *opts)
{
struct sshauthopt *old = auth_opts;
const char *emsg = NULL;
debug_f("setting new authentication options");
if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) {
error("Inconsistent authentication options: %s", emsg);
return -1;
}
return 0;
}
void
auth_restrict_session(struct ssh *ssh)
{
struct sshauthopt *restricted;
debug_f("restricting session");
if ((restricted = sshauthopt_new()) == NULL)
fatal_f("sshauthopt_new failed");
restricted->permit_pty_flag = 1;
restricted->restricted = 1;
if (auth_activate_options(ssh, restricted) != 0)
fatal_f("failed to restrict session");
sshauthopt_free(restricted);
}
