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Systemd/src/login/logind-session.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "sd-id128.h"
#include "sd-messages.h"
#include "strv.h"
#include "util.h"
#include "mkdir.h"
#include "path-util.h"
#include "fileio.h"
#include "audit.h"
#include "bus-util.h"
#include "bus-error.h"
#include "logind-session.h"
static unsigned devt_hash_func(const void *p) {
uint64_t u = *(const dev_t*)p;
return uint64_hash_func(&u);
}
static int devt_compare_func(const void *_a, const void *_b) {
dev_t a, b;
a = *(const dev_t*) _a;
b = *(const dev_t*) _b;
return a < b ? -1 : (a > b ? 1 : 0);
}
Session* session_new(Manager *m, const char *id) {
Session *s;
assert(m);
assert(id);
assert(session_id_valid(id));
s = new0(Session, 1);
if (!s)
return NULL;
s->state_file = strappend("/run/systemd/sessions/", id);
if (!s->state_file) {
free(s);
return NULL;
}
s->devices = hashmap_new(devt_hash_func, devt_compare_func);
if (!s->devices) {
free(s->state_file);
free(s);
return NULL;
}
s->id = path_get_file_name(s->state_file);
if (hashmap_put(m->sessions, s->id, s) < 0) {
hashmap_free(s->devices);
free(s->state_file);
free(s);
return NULL;
}
s->manager = m;
s->fifo_fd = -1;
return s;
}
void session_free(Session *s) {
SessionDevice *sd;
assert(s);
if (s->in_gc_queue)
LIST_REMOVE(gc_queue, s->manager->session_gc_queue, s);
session_remove_fifo(s);
session_drop_controller(s);
while ((sd = hashmap_first(s->devices)))
session_device_free(sd);
hashmap_free(s->devices);
if (s->user) {
LIST_REMOVE(sessions_by_user, s->user->sessions, s);
if (s->user->display == s)
s->user->display = NULL;
}
if (s->seat) {
if (s->seat->active == s)
s->seat->active = NULL;
if (s->seat->pending_switch == s)
s->seat->pending_switch = NULL;
LIST_REMOVE(sessions_by_seat, s->seat->sessions, s);
}
if (s->scope) {
hashmap_remove(s->manager->session_units, s->scope);
free(s->scope);
}
free(s->scope_job);
sd_bus_message_unref(s->create_message);
free(s->tty);
free(s->display);
free(s->remote_host);
free(s->remote_user);
free(s->service);
hashmap_remove(s->manager->sessions, s->id);
free(s->state_file);
free(s);
}
void session_set_user(Session *s, User *u) {
assert(s);
assert(!s->user);
s->user = u;
LIST_PREPEND(sessions_by_user, u->sessions, s);
}
int session_save(Session *s) {
_cleanup_free_ char *temp_path = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r = 0;
assert(s);
if (!s->user)
return -ESTALE;
if (!s->started)
return 0;
r = mkdir_safe_label("/run/systemd/sessions", 0755, 0, 0);
if (r < 0)
goto finish;
r = fopen_temporary(s->state_file, &f, &temp_path);
if (r < 0)
goto finish;
assert(s->user);
fchmod(fileno(f), 0644);
fprintf(f,
"# This is private data. Do not parse.\n"
"UID=%lu\n"
"USER=%s\n"
"ACTIVE=%i\n"
"STATE=%s\n"
"REMOTE=%i\n",
(unsigned long) s->user->uid,
s->user->name,
session_is_active(s),
session_state_to_string(session_get_state(s)),
s->remote);
if (s->type >= 0)
fprintf(f, "TYPE=%s\n", session_type_to_string(s->type));
if (s->class >= 0)
fprintf(f, "CLASS=%s\n", session_class_to_string(s->class));
if (s->scope)
fprintf(f, "SCOPE=%s\n", s->scope);
if (s->scope_job)
fprintf(f, "SCOPE_JOB=%s\n", s->scope_job);
if (s->fifo_path)
fprintf(f, "FIFO=%s\n", s->fifo_path);
if (s->seat)
fprintf(f, "SEAT=%s\n", s->seat->id);
if (s->tty)
fprintf(f, "TTY=%s\n", s->tty);
if (s->display)
fprintf(f, "DISPLAY=%s\n", s->display);
if (s->remote_host)
fprintf(f, "REMOTE_HOST=%s\n", s->remote_host);
if (s->remote_user)
fprintf(f, "REMOTE_USER=%s\n", s->remote_user);
if (s->service)
fprintf(f, "SERVICE=%s\n", s->service);
if (s->seat && seat_has_vts(s->seat))
fprintf(f, "VTNR=%i\n", s->vtnr);
if (s->leader > 0)
fprintf(f, "LEADER=%lu\n", (unsigned long) s->leader);
if (s->audit_id > 0)
fprintf(f, "AUDIT=%"PRIu32"\n", s->audit_id);
if (dual_timestamp_is_set(&s->timestamp))
fprintf(f,
"REALTIME=%llu\n"
"MONOTONIC=%llu\n",
(unsigned long long) s->timestamp.realtime,
(unsigned long long) s->timestamp.monotonic);
fflush(f);
if (ferror(f) || rename(temp_path, s->state_file) < 0) {
r = -errno;
unlink(s->state_file);
unlink(temp_path);
}
finish:
if (r < 0)
log_error("Failed to save session data for %s: %s", s->id, strerror(-r));
return r;
}
int session_load(Session *s) {
_cleanup_free_ char *remote = NULL,
*seat = NULL,
*vtnr = NULL,
*leader = NULL,
*type = NULL,
*class = NULL,
*uid = NULL,
*realtime = NULL,
*monotonic = NULL;
int k, r;
assert(s);
r = parse_env_file(s->state_file, NEWLINE,
"REMOTE", &remote,
"SCOPE", &s->scope,
"SCOPE_JOB", &s->scope_job,
"FIFO", &s->fifo_path,
"SEAT", &seat,
"TTY", &s->tty,
"DISPLAY", &s->display,
"REMOTE_HOST", &s->remote_host,
"REMOTE_USER", &s->remote_user,
"SERVICE", &s->service,
"VTNR", &vtnr,
"LEADER", &leader,
"TYPE", &type,
"CLASS", &class,
"UID", &uid,
"REALTIME", &realtime,
"MONOTONIC", &monotonic,
NULL);
if (r < 0) {
log_error("Failed to read %s: %s", s->state_file, strerror(-r));
return r;
}
if (!s->user) {
uid_t u;
User *user;
if (!uid) {
log_error("UID not specified for session %s", s->id);
return -ENOENT;
}
r = parse_uid(uid, &u);
if (r < 0) {
log_error("Failed to parse UID value %s for session %s.", uid, s->id);
return r;
}
user = hashmap_get(s->manager->users, ULONG_TO_PTR((unsigned long) u));
if (!user) {
log_error("User of session %s not known.", s->id);
return -ENOENT;
}
session_set_user(s, user);
}
if (remote) {
k = parse_boolean(remote);
if (k >= 0)
s->remote = k;
}
if (seat && !s->seat) {
Seat *o;
o = hashmap_get(s->manager->seats, seat);
if (o)
seat_attach_session(o, s);
}
if (vtnr && s->seat && seat_has_vts(s->seat)) {
int v;
k = safe_atoi(vtnr, &v);
if (k >= 0 && v >= 1)
s->vtnr = v;
}
if (leader) {
k = parse_pid(leader, &s->leader);
if (k >= 0)
audit_session_from_pid(s->leader, &s->audit_id);
}
if (type) {
SessionType t;
t = session_type_from_string(type);
if (t >= 0)
s->type = t;
}
if (class) {
SessionClass c;
c = session_class_from_string(class);
if (c >= 0)
s->class = c;
}
if (s->fifo_path) {
int fd;
/* If we open an unopened pipe for reading we will not
get an EOF. to trigger an EOF we hence open it for
reading, but close it right-away which then will
trigger the EOF. */
fd = session_create_fifo(s);
if (fd >= 0)
close_nointr_nofail(fd);
}
if (realtime) {
unsigned long long l;
if (sscanf(realtime, "%llu", &l) > 0)
s->timestamp.realtime = l;
}
if (monotonic) {
unsigned long long l;
if (sscanf(monotonic, "%llu", &l) > 0)
s->timestamp.monotonic = l;
}
return r;
}
int session_activate(Session *s) {
unsigned int num_pending;
assert(s);
assert(s->user);
if (!s->seat)
return -ENOTSUP;
if (s->seat->active == s)
return 0;
/* on seats with VTs, we let VTs manage session-switching */
if (seat_has_vts(s->seat)) {
if (s->vtnr <= 0)
return -ENOTSUP;
return chvt(s->vtnr);
}
/* On seats without VTs, we implement session-switching in logind. We
* try to pause all session-devices and wait until the session
* controller acknowledged them. Once all devices are asleep, we simply
* switch the active session and be done.
* We save the session we want to switch to in seat->pending_switch and
* seat_complete_switch() will perform the final switch. */
s->seat->pending_switch = s;
/* if no devices are running, immediately perform the session switch */
num_pending = session_device_try_pause_all(s);
if (!num_pending)
seat_complete_switch(s->seat);
return 0;
}
static int session_link_x11_socket(Session *s) {
_cleanup_free_ char *t = NULL, *f = NULL;
char *c;
size_t k;
assert(s);
assert(s->user);
assert(s->user->runtime_path);
if (s->user->display)
return 0;
if (!s->display || !display_is_local(s->display))
return 0;
k = strspn(s->display+1, "0123456789");
f = new(char, sizeof("/tmp/.X11-unix/X") + k);
if (!f)
return log_oom();
c = stpcpy(f, "/tmp/.X11-unix/X");
memcpy(c, s->display+1, k);
c[k] = 0;
if (access(f, F_OK) < 0) {
log_warning("Session %s has display %s with non-existing socket %s.", s->id, s->display, f);
return -ENOENT;
}
/* Note that this cannot be in a subdir to avoid
* vulnerabilities since we are privileged but the runtime
* path is owned by the user */
t = strappend(s->user->runtime_path, "/X11-display");
if (!t)
return log_oom();
if (link(f, t) < 0) {
if (errno == EEXIST) {
unlink(t);
if (link(f, t) >= 0)
goto done;
}
if (symlink(f, t) < 0) {
if (errno == EEXIST) {
unlink(t);
if (symlink(f, t) >= 0)
goto done;
}
log_error("Failed to link %s to %s: %m", f, t);
return -errno;
}
}
done:
log_info("Linked %s to %s.", f, t);
s->user->display = s;
return 0;
}
static int session_start_scope(Session *s) {
int r;
assert(s);
assert(s->user);
assert(s->user->slice);
if (!s->scope) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_free_ char *description = NULL;
const char *kill_mode;
char *scope, *job;
description = strjoin("Session ", s->id, " of user ", s->user->name, NULL);
if (!description)
return log_oom();
scope = strjoin("session-", s->id, ".scope", NULL);
if (!scope)
return log_oom();
kill_mode = manager_shall_kill(s->manager, s->user->name) ? "control-group" : "none";
r = manager_start_scope(s->manager, scope, s->leader, s->user->slice, description, "systemd-user-sessions.service", kill_mode, &error, &job);
if (r < 0) {
log_error("Failed to start session scope %s: %s %s",
scope, bus_error_message(&error, r), error.name);
free(scope);
return r;
} else {
s->scope = scope;
free(s->scope_job);
s->scope_job = job;
}
}
if (s->scope)
hashmap_put(s->manager->session_units, s->scope, s);
return 0;
}
int session_start(Session *s) {
int r;
assert(s);
if (!s->user)
return -ESTALE;
if (s->started)
return 0;
r = user_start(s->user);
if (r < 0)
return r;
/* Create cgroup */
r = session_start_scope(s);
if (r < 0)
return r;
log_struct(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
MESSAGE_ID(SD_MESSAGE_SESSION_START),
"SESSION_ID=%s", s->id,
"USER_ID=%s", s->user->name,
"LEADER=%lu", (unsigned long) s->leader,
"MESSAGE=New session %s of user %s.", s->id, s->user->name,
NULL);
/* Create X11 symlink */
session_link_x11_socket(s);
if (!dual_timestamp_is_set(&s->timestamp))
dual_timestamp_get(&s->timestamp);
if (s->seat)
seat_read_active_vt(s->seat);
s->started = true;
/* Save session data */
session_save(s);
user_save(s->user);
session_send_signal(s, true);
if (s->seat) {
seat_save(s->seat);
if (s->seat->active == s)
seat_send_changed(s->seat, "Sessions", "ActiveSession", NULL);
else
seat_send_changed(s->seat, "Sessions", NULL);
}
user_send_changed(s->user, "Sessions", NULL);
return 0;
}
static int session_stop_scope(Session *s) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
char *job;
int r;
assert(s);
if (!s->scope)
return 0;
r = manager_stop_unit(s->manager, s->scope, &error, &job);
if (r < 0) {
log_error("Failed to stop session scope: %s", bus_error_message(&error, r));
return r;
}
free(s->scope_job);
s->scope_job = job;
return 0;
}
static int session_unlink_x11_socket(Session *s) {
_cleanup_free_ char *t = NULL;
int r;
assert(s);
assert(s->user);
if (s->user->display != s)
return 0;
s->user->display = NULL;
t = strappend(s->user->runtime_path, "/X11-display");
if (!t)
return log_oom();
r = unlink(t);
return r < 0 ? -errno : 0;
}
int session_stop(Session *s) {
int r;
assert(s);
if (!s->user)
return -ESTALE;
/* Kill cgroup */
r = session_stop_scope(s);
session_save(s);
user_save(s->user);
return r;
}
int session_finalize(Session *s) {
int r = 0;
SessionDevice *sd;
assert(s);
if (!s->user)
return -ESTALE;
if (s->started)
log_struct(s->type == SESSION_TTY || s->type == SESSION_X11 ? LOG_INFO : LOG_DEBUG,
MESSAGE_ID(SD_MESSAGE_SESSION_STOP),
"SESSION_ID=%s", s->id,
"USER_ID=%s", s->user->name,
"LEADER=%lu", (unsigned long) s->leader,
"MESSAGE=Removed session %s.", s->id,
NULL);
/* Kill session devices */
while ((sd = hashmap_first(s->devices)))
session_device_free(sd);
/* Remove X11 symlink */
session_unlink_x11_socket(s);
unlink(s->state_file);
session_add_to_gc_queue(s);
user_add_to_gc_queue(s->user);
if (s->started) {
session_send_signal(s, false);
s->started = false;
}
if (s->seat) {
if (s->seat->active == s)
seat_set_active(s->seat, NULL);
seat_send_changed(s->seat, "Sessions", NULL);
seat_save(s->seat);
}
user_send_changed(s->user, "Sessions", NULL);
user_save(s->user);
return r;
}
bool session_is_active(Session *s) {
assert(s);
if (!s->seat)
return true;
return s->seat->active == s;
}
static int get_tty_atime(const char *tty, usec_t *atime) {
_cleanup_free_ char *p = NULL;
struct stat st;
assert(tty);
assert(atime);
if (!path_is_absolute(tty)) {
p = strappend("/dev/", tty);
if (!p)
return -ENOMEM;
tty = p;
} else if (!path_startswith(tty, "/dev/"))
return -ENOENT;
if (lstat(tty, &st) < 0)
return -errno;
*atime = timespec_load(&st.st_atim);
return 0;
}
static int get_process_ctty_atime(pid_t pid, usec_t *atime) {
_cleanup_free_ char *p = NULL;
int r;
assert(pid > 0);
assert(atime);
r = get_ctty(pid, NULL, &p);
if (r < 0)
return r;
return get_tty_atime(p, atime);
}
int session_get_idle_hint(Session *s, dual_timestamp *t) {
usec_t atime = 0, n;
int r;
assert(s);
/* Explicit idle hint is set */
if (s->idle_hint) {
if (t)
*t = s->idle_hint_timestamp;
return s->idle_hint;
}
/* Graphical sessions should really implement a real
* idle hint logic */
if (s->display)
goto dont_know;
/* For sessions with an explicitly configured tty, let's check
* its atime */
if (s->tty) {
r = get_tty_atime(s->tty, &atime);
if (r >= 0)
goto found_atime;
}
/* For sessions with a leader but no explicitly configured
* tty, let's check the controlling tty of the leader */
if (s->leader > 0) {
r = get_process_ctty_atime(s->leader, &atime);
if (r >= 0)
goto found_atime;
}
dont_know:
if (t)
*t = s->idle_hint_timestamp;
return 0;
found_atime:
if (t)
dual_timestamp_from_realtime(t, atime);
n = now(CLOCK_REALTIME);
if (s->manager->idle_action_usec <= 0)
return 0;
return atime + s->manager->idle_action_usec <= n;
}
void session_set_idle_hint(Session *s, bool b) {
assert(s);
if (s->idle_hint == b)
return;
s->idle_hint = b;
dual_timestamp_get(&s->idle_hint_timestamp);
session_send_changed(s, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
if (s->seat)
seat_send_changed(s->seat, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
user_send_changed(s->user, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
manager_send_changed(s->manager, "IdleHint", "IdleSinceHint", "IdleSinceHintMonotonic", NULL);
}
static int session_dispatch_fifo(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
Session *s = userdata;
assert(s);
assert(s->fifo_fd == fd);
/* EOF on the FIFO means the session died abnormally. */
session_remove_fifo(s);
session_stop(s);
return 1;
}
int session_create_fifo(Session *s) {
int r;
assert(s);
/* Create FIFO */
if (!s->fifo_path) {
r = mkdir_safe_label("/run/systemd/sessions", 0755, 0, 0);
if (r < 0)
return r;
if (asprintf(&s->fifo_path, "/run/systemd/sessions/%s.ref", s->id) < 0)
return -ENOMEM;
if (mkfifo(s->fifo_path, 0600) < 0 && errno != EEXIST)
return -errno;
}
/* Open reading side */
if (s->fifo_fd < 0) {
s->fifo_fd = open(s->fifo_path, O_RDONLY|O_CLOEXEC|O_NDELAY);
if (s->fifo_fd < 0)
return -errno;
}
if (!s->fifo_event_source) {
r = sd_event_add_io(s->manager->event, s->fifo_fd, 0, session_dispatch_fifo, s, &s->fifo_event_source);
if (r < 0)
return r;
r = sd_event_source_set_priority(s->fifo_event_source, SD_EVENT_PRIORITY_IDLE);
if (r < 0)
return r;
}
/* Open writing side */
r = open(s->fifo_path, O_WRONLY|O_CLOEXEC|O_NDELAY);
if (r < 0)
return -errno;
return r;
}
void session_remove_fifo(Session *s) {
assert(s);
if (s->fifo_event_source)
s->fifo_event_source = sd_event_source_unref(s->fifo_event_source);
if (s->fifo_fd >= 0) {
close_nointr_nofail(s->fifo_fd);
s->fifo_fd = -1;
}
if (s->fifo_path) {
unlink(s->fifo_path);
free(s->fifo_path);
s->fifo_path = NULL;
}
}
bool session_check_gc(Session *s, bool drop_not_started) {
int r;
assert(s);
if (drop_not_started && !s->started)
return false;
if (!s->user)
return false;
if (s->fifo_fd >= 0) {
r = pipe_eof(s->fifo_fd);
if (r < 0)
return true;
if (r == 0)
return true;
}
if (s->scope_job && manager_job_is_active(s->manager, s->scope_job))
return true;
if (s->scope && manager_unit_is_active(s->manager, s->scope))
return true;
return false;
}
void session_add_to_gc_queue(Session *s) {
assert(s);
if (s->in_gc_queue)
return;
LIST_PREPEND(gc_queue, s->manager->session_gc_queue, s);
s->in_gc_queue = true;
}
SessionState session_get_state(Session *s) {
assert(s);
if (s->closing)
return SESSION_CLOSING;
if (s->scope_job)
return SESSION_OPENING;
if (s->fifo_fd < 0)
return SESSION_CLOSING;
if (session_is_active(s))
return SESSION_ACTIVE;
return SESSION_ONLINE;
}
int session_kill(Session *s, KillWho who, int signo) {
assert(s);
if (!s->scope)
return -ESRCH;
return manager_kill_unit(s->manager, s->scope, who, signo, NULL);
}
bool session_is_controller(Session *s, const char *sender) {
assert(s);
return streq_ptr(s->controller, sender);
}
int session_set_controller(Session *s, const char *sender, bool force) {
char *t;
int r;
assert(s);
assert(sender);
if (session_is_controller(s, sender))
return 0;
if (s->controller && !force)
return -EBUSY;
t = strdup(sender);
if (!t)
return -ENOMEM;
r = manager_watch_busname(s->manager, sender);
if (r) {
free(t);
return r;
}
session_drop_controller(s);
s->controller = t;
return 0;
}
void session_drop_controller(Session *s) {
SessionDevice *sd;
assert(s);
if (!s->controller)
return;
manager_drop_busname(s->manager, s->controller);
free(s->controller);
s->controller = NULL;
/* Drop all devices as they're now unused. Do that after the controller
* is released to avoid sending out useles dbus signals. */
while ((sd = hashmap_first(s->devices)))
session_device_free(sd);
}
static const char* const session_state_table[_SESSION_STATE_MAX] = {
[SESSION_OPENING] = "opening",
[SESSION_ONLINE] = "online",
[SESSION_ACTIVE] = "active",
[SESSION_CLOSING] = "closing"
};
DEFINE_STRING_TABLE_LOOKUP(session_state, SessionState);
static const char* const session_type_table[_SESSION_TYPE_MAX] = {
[SESSION_TTY] = "tty",
[SESSION_X11] = "x11",
[SESSION_UNSPECIFIED] = "unspecified"
};
DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);
static const char* const session_class_table[_SESSION_CLASS_MAX] = {
[SESSION_USER] = "user",
[SESSION_GREETER] = "greeter",
[SESSION_LOCK_SCREEN] = "lock-screen",
[SESSION_BACKGROUND] = "background"
};
DEFINE_STRING_TABLE_LOOKUP(session_class, SessionClass);
static const char* const kill_who_table[_KILL_WHO_MAX] = {
[KILL_LEADER] = "leader",
[KILL_ALL] = "all"
};
DEFINE_STRING_TABLE_LOOKUP(kill_who, KillWho);
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