pam-module.c revision 8c6db8336536916d0476ff8233e0abf40a2f6aab
/*-*- Mode: C; c-basic-offset: 8 -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <fcntl.h>
#include <sys/file.h>
#include <pwd.h>
#include <security/pam_modules.h>
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
#include <security/pam_misc.h>
#include <libcgroup.h>
#include "util.h"
#include "cgroup-util.h"
#include "macro.h"
#include "sd-daemon.h"
static int parse_argv(pam_handle_t *handle,
int argc, const char **argv,
bool *create_session,
bool *kill_session,
bool *kill_user) {
unsigned i;
assert(argc >= 0);
assert(argc == 0 || argv);
for (i = 0; i < (unsigned) argc; i++) {
int k;
if (startswith(argv[i], "create-session=")) {
if ((k = parse_boolean(argv[i] + 15)) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument.");
return k;
}
if (create_session)
*create_session = k;
} else if (startswith(argv[i], "kill-session=")) {
if ((k = parse_boolean(argv[i] + 13)) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
return k;
}
if (kill_session)
*kill_session = k;
} else if (startswith(argv[i], "kill-user=")) {
if ((k = parse_boolean(argv[i] + 10)) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument.");
return k;
}
if (kill_user)
*kill_user = k;
} else {
pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
return -EINVAL;
}
}
if (kill_session && *kill_session && kill_user)
*kill_user = true;
return 0;
}
static int open_file_and_lock(const char *fn) {
int fd;
assert(fn);
if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
return -errno;
if (flock(fd, LOCK_EX) < 0)
return -errno;
return fd;
}
static uint32_t combine32(unsigned long long u) {
uint32_t r = 0;
unsigned i;
for (i = 0; i < sizeof(u)/4; i ++)
r ^= (uint32_t) ((u >> (i*32)) & 0xFFFFFFFFULL);
return r;
}
static char *generate_session_cookie(void) {
char *machine;
char *cookie;
unsigned long long r;
usec_t u;
int k;
if (getmachineid_malloc(&machine) < 0)
if (!(machine = gethostname_malloc()))
return NULL;
r = random_ull();
u = now(CLOCK_REALTIME);
k = asprintf(&cookie, "%s-%lu-%lu",
machine,
(unsigned long) combine32(r),
(unsigned long) combine32((unsigned long long) u));
free(machine);
return k < 0 ? NULL : cookie;
}
static int get_user_data(
pam_handle_t *handle,
const char **ret_username,
struct passwd **ret_pw) {
const char *username;
struct passwd *pw;
int r;
assert(handle);
assert(ret_username);
assert(ret_pw);
if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to get user name.");
return r;
}
if (!username || !*username) {
pam_syslog(handle, LOG_ERR, "User name not valid.");
return PAM_AUTH_ERR;
}
if (!(pw = pam_modutil_getpwnam(handle, username))) {
pam_syslog(handle, LOG_ERR, "Failed to get user data.");
return PAM_USER_UNKNOWN;
}
*ret_pw = pw;
*ret_username = username;
return PAM_SUCCESS;
}
static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) {
int r;
assert(handle);
assert(group);
if (attach)
r = cg_create_and_attach("name=systemd", group, 0);
else
r = cg_create("name=systemd", group);
if (r < 0) {
pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
return PAM_SESSION_ERR;
}
if ((r = cg_set_task_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0 ||
(r = cg_set_group_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
return PAM_SESSION_ERR;
}
return PAM_SUCCESS;
}
_public_ PAM_EXTERN int pam_sm_open_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
const char *username = NULL;
struct passwd *pw;
int r;
char *buf = NULL;
int lock_fd = -1;
bool create_session = true;
assert(handle);
pam_syslog(handle, LOG_INFO, "pam-systemd initializing");
if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0)
return PAM_SESSION_ERR;
/* Make this a NOP on non-systemd systems */
if (sd_booted() <= 0)
return PAM_SUCCESS;
if ((r = cgroup_init()) != 0) {
pam_syslog(handle, LOG_ERR, "libcgroup initialization failed: %s", cgroup_strerror(r));
r = PAM_SESSION_ERR;
goto finish;
}
if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
goto finish;
if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m");
r = PAM_SYSTEM_ERR;
goto finish;
}
if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
r = PAM_SYSTEM_ERR;
goto finish;
}
/* Create /var/run/$USER */
free(buf);
if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) {
r = PAM_BUF_ERR;
goto finish;
}
if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) {
pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m");
r = PAM_SYSTEM_ERR;
goto finish;
} else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
goto finish;
}
free(buf);
buf = NULL;
if (create_session) {
const char *cookie;
/* Reuse or create XDG session ID */
if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
if (!(buf = generate_session_cookie())) {
r = PAM_BUF_ERR;
goto finish;
}
if ((r = pam_misc_setenv(handle, "XDG_SESSION_COOKIE", buf, 0)) != PAM_SUCCESS) {
pam_syslog(handle, LOG_ERR, "Failed to set cookie.");
goto finish;
}
if (!(cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
pam_syslog(handle, LOG_ERR, "Failed to get cookie.");
r = PAM_SESSION_ERR;
goto finish;
}
}
r = asprintf(&buf, "/user/%s/%s", username, cookie);
} else
r = asprintf(&buf, "/user/%s/no-session", username);
if (r < 0) {
r = PAM_BUF_ERR;
goto finish;
}
if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS)
goto finish;
r = PAM_SUCCESS;
finish:
free(buf);
if (lock_fd >= 0)
close_nointr_nofail(lock_fd);
return r;
}
static int session_remains(pam_handle_t *handle, const char *user_path) {
struct cgroup_file_info info;
int level = 0, r;
void *iterator = NULL;
bool remains = false;
zero(info);
r = cgroup_walk_tree_begin("name=systemd", user_path, 0, &iterator, &info, &level);
while (r == 0) {
if (info.type != CGROUP_FILE_TYPE_DIR)
goto next;
if (streq(info.path, ""))
goto next;
if (streq(info.path, "no-session"))
goto next;
remains = true;
break;
next:
r = cgroup_walk_tree_next(0, &iterator, &info, level);
}
if (remains)
r = 1;
else if (r == 0 || r == ECGEOF)
r = 0;
else
r = cg_translate_error(r, errno);
assert_se(cgroup_walk_tree_end(&iterator) == 0);
return r;
}
_public_ PAM_EXTERN int pam_sm_close_session(
pam_handle_t *handle,
int flags,
int argc, const char **argv) {
const char *username = NULL;
bool kill_session = false;
bool kill_user = false;
int lock_fd = -1, r;
char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
const char *cookie;
struct passwd *pw;
assert(handle);
if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0)
return PAM_SESSION_ERR;
/* Make this a NOP on non-systemd systems */
if (sd_booted() <= 0)
return PAM_SUCCESS;
if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
goto finish;
if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
r = PAM_SYSTEM_ERR;
goto finish;
}
if (asprintf(&user_path, "/user/%s", username) < 0) {
r = PAM_BUF_ERR;
goto finish;
}
if ((cookie = pam_getenv(handle, "XDG_SESSION_COOKIE"))) {
if (asprintf(&session_path, "/user/%s/%s", username, cookie) < 0 ||
asprintf(&nosession_path, "/user/%s/no-session", username) < 0) {
r = PAM_BUF_ERR;
goto finish;
}
if (kill_session) {
pam_syslog(handle, LOG_INFO, "KILLING ENTER");
/* Kill processes in session cgroup */
if ((r = cg_kill_recursive_and_wait("name=systemd", session_path)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
pam_syslog(handle, LOG_INFO, "KILLING EXIT");
} else {
/* Migrate processes from session to
* no-session cgroup. First, try to create the
* no-session group in case it doesn't exist
* yet. */
create_user_group(handle, nosession_path, pw, 0);
if ((r = cg_migrate_recursive("name=systemd", session_path, nosession_path, false)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
}
/* Delete session cgroup */
if (r < 0)
pam_syslog(handle, LOG_INFO, "Couldn't empty session cgroup, not deleting.");
else {
if ((r = cg_delete("name=systemd", session_path)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to delete session cgroup: %s", strerror(-r));
}
}
/* GC user tree */
cg_trim("name=systemd", user_path, false);
if ((r = session_remains(handle, user_path)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
/* Kill user processes not attached to any session */
if (kill_user && r == 0) {
/* Kill no-session cgroup */
if ((r = cg_kill_recursive_and_wait("name=systemd", user_path)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
} else {
if ((r = cg_is_empty_recursive("name=systemd", user_path, true)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
/* If we managed to kill somebody, don't cleanup the cgroup. */
if (r == 0)
r = -EBUSY;
}
if (r >= 0) {
const char *runtime_dir;
/* Remove user cgroup */
if ((r = cg_delete("name=systemd", user_path)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
/* This will migrate us to the /user cgroup. */
if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
if ((r = rm_rf(runtime_dir, false, true)) < 0)
pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
}
r = PAM_SUCCESS;
finish:
if (lock_fd >= 0)
close_nointr_nofail(lock_fd);
free(session_path);
free(nosession_path);
free(user_path);
return r;
}