src/logind-session.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26 #include "logind-session.h"
  27 #include "strv.h"
  28 #include "util.h"
  29 #include "cgroup-util.h"
  30
  31 Session* session_new(Manager *m, User *u, const char *id) {
  32         Session *s;
  33
  34         assert(m);
  35         assert(id);
  36
  37         s = new0(Session, 1);
  38         if (!s)
  39                 return NULL;
  40
  41         s->state_file = strappend("/run/systemd/session/", id);
  42         if (!s->state_file) {
  43                 free(s);
  44                 return NULL;
  45         }
  46
  47         s->id = file_name_from_path(s->state_file);
  48
  49         if (hashmap_put(m->sessions, s->id, s) < 0) {
  50                 free(s->id);
  51                 free(s);
  52                 return NULL;
  53         }
  54
  55         s->manager = m;
  56         s->pipe_fd = -1;
  57         s->user = u;
  58
  59         LIST_PREPEND(Session, sessions_by_user, u->sessions, s);
  60
  61         return s;
  62 }
  63
  64 void session_free(Session *s) {
  65         assert(s);
  66
  67         if (s->in_gc_queue)
  68                 LIST_REMOVE(Session, gc_queue, s->manager->session_gc_queue, s);
  69
  70         if (s->user) {
  71                 LIST_REMOVE(Session, sessions_by_user, s->user->sessions, s);
  72
  73                 if (s->user->display == s)
  74                         s->user->display = NULL;
  75         }
  76
  77         if (s->seat)
  78                 LIST_REMOVE(Session, sessions_by_seat, s->seat->sessions, s);
  79
  80         free(s->cgroup_path);
  81         strv_free(s->controllers);
  82
  83         free(s->tty);
  84         free(s->display);
  85         free(s->remote_host);
  86
  87         hashmap_remove(s->manager->sessions, s->id);
  88
  89         free(s->state_file);
  90         free(s);
  91 }
  92
  93 int session_save(Session *s) {
  94         FILE *f;
  95         int r = 0;
  96         char *temp_path;
  97
  98         assert(s);
  99
 100         r = safe_mkdir("/run/systemd/session", 0755, 0, 0);
 101         if (r < 0)
 102                 goto finish;
 103
 104         r = fopen_temporary(s->state_file, &f, &temp_path);
 105         if (r < 0)
 106                 goto finish;
 107
 108         assert(s->user);
 109
 110         fchmod(fileno(f), 0644);
 111
 112         fprintf(f,
 113                 "# This is private data. Do not parse.\n"
 114                 "UID=%lu\n"
 115                 "USER=%s\n"
 116                 "ACTIVE=%i\n"
 117                 "REMOTE=%i\n"
 118                 "KILL_PROCESSES=%i\n",
 119                 (unsigned long) s->user->uid,
 120                 s->user->name,
 121                 session_is_active(s),
 122                 s->remote,
 123                 s->kill_processes);
 124
 125         if (s->cgroup_path)
 126                 fprintf(f,
 127                         "CGROUP=%s\n",
 128                         s->cgroup_path);
 129
 130         if (s->seat)
 131                 fprintf(f,
 132                         "SEAT=%s\n",
 133                         s->seat->id);
 134
 135         if (s->tty)
 136                 fprintf(f,
 137                         "TTY=%s\n",
 138                         s->tty);
 139
 140         if (s->display)
 141                 fprintf(f,
 142                         "DISPLAY=%s\n",
 143                         s->display);
 144
 145         if (s->remote_host)
 146                 fprintf(f,
 147                         "REMOTE_HOST=%s\n",
 148                         s->remote_host);
 149
 150         if (s->seat && s->seat->manager->vtconsole == s->seat)
 151                 fprintf(f,
 152                         "VTNR=%i\n",
 153                         s->vtnr);
 154
 155         if (s->leader > 0)
 156                 fprintf(f,
 157                         "LEADER=%lu\n",
 158                         (unsigned long) s->leader);
 159
 160         if (s->audit_id > 0)
 161                 fprintf(f,
 162                         "AUDIT=%llu\n",
 163                         (unsigned long long) s->audit_id);
 164
 165         fflush(f);
 166
 167         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 168                 r = -errno;
 169                 unlink(s->state_file);
 170                 unlink(temp_path);
 171         }
 172
 173         fclose(f);
 174         free(temp_path);
 175
 176 finish:
 177         if (r < 0)
 178                 log_error("Failed to save session data for %s: %s", s->id, strerror(-r));
 179
 180         return r;
 181 }
 182
 183 int session_load(Session *s) {
 184         assert(s);
 185
 186         return 0;
 187 }
 188
 189 int session_activate(Session *s) {
 190         int r;
 191         Session *old_active;
 192
 193         assert(s);
 194
 195         if (s->vtnr < 0)
 196                 return -ENOTSUP;
 197
 198         if (!s->seat)
 199                 return -ENOTSUP;
 200
 201         if (s->seat->active == s)
 202                 return 0;
 203
 204         assert(s->manager->vtconsole == s->seat);
 205
 206         r = chvt(s->vtnr);
 207         if (r < 0)
 208                 return r;
 209
 210         old_active = s->seat->active;
 211         s->seat->active = s;
 212
 213         return seat_apply_acls(s->seat, old_active);
 214 }
 215
 216 bool x11_display_is_local(const char *display) {
 217         assert(display);
 218
 219         return
 220                 display[0] == ':' &&
 221                 display[1] >= '0' &&
 222                 display[1] <= '9';
 223 }
 224
 225 static int session_link_x11_socket(Session *s) {
 226         char *t, *f, *c;
 227         size_t k;
 228
 229         assert(s);
 230         assert(s->user);
 231         assert(s->user->runtime_path);
 232
 233         if (s->user->display)
 234                 return 0;
 235
 236         if (!s->display || !x11_display_is_local(s->display))
 237                 return 0;
 238
 239         k = strspn(s->display+1, "0123456789");
 240         f = new(char, sizeof("/tmp/.X11-unix/X") + k);
 241         if (!f) {
 242                 log_error("Out of memory");
 243                 return -ENOMEM;
 244         }
 245
 246         c = stpcpy(f, "/tmp/.X11-unix/X");
 247         memcpy(c, s->display+1, k);
 248         c[k] = 0;
 249
 250         if (access(f, F_OK) < 0) {
 251                 log_warning("Session %s has display %s with nonexisting socket %s.", s->id, s->display, f);
 252                 free(f);
 253                 return -ENOENT;
 254         }
 255
 256         t = strappend(s->user->runtime_path, "/display");
 257         if (!t) {
 258                 log_error("Out of memory");
 259                 free(f);
 260                 return -ENOMEM;
 261         }
 262
 263         if (link(f, t) < 0) {
 264                 if (errno == EEXIST) {
 265                         unlink(t);
 266
 267                         if (link(f, t) >= 0)
 268                                 goto done;
 269                 }
 270
 271                 if (symlink(f, t) < 0) {
 272
 273                         if (errno == EEXIST) {
 274                                 unlink(t);
 275
 276                                 if (symlink(f, t) >= 0)
 277                                         goto done;
 278                         }
 279
 280                         log_error("Failed to link %s to %s: %m", f, t);
 281                         free(f);
 282                         free(t);
 283                         return -errno;
 284                 }
 285         }
 286
 287 done:
 288         log_info("Linked %s to %s.", f, t);
 289         free(f);
 290         free(t);
 291
 292         s->user->display = s;
 293
 294         return 0;
 295 }
 296
 297 static int session_create_cgroup(Session *s) {
 298         char **k;
 299         char *p;
 300         int r;
 301
 302         assert(s);
 303         assert(s->user);
 304         assert(s->user->cgroup_path);
 305
 306         if (!s->cgroup_path) {
 307                 if (asprintf(&p, "%s/%s", s->user->cgroup_path, s->id) < 0) {
 308                         log_error("Out of memory");
 309                         return -ENOMEM;
 310                 }
 311         } else
 312                 p = s->cgroup_path;
 313
 314         if (s->leader > 0)
 315                 r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, p, s->leader);
 316         else
 317                 r = cg_create(SYSTEMD_CGROUP_CONTROLLER, p);
 318
 319         if (r < 0) {
 320                 free(p);
 321                 s->cgroup_path = NULL;
 322                 log_error("Failed to create "SYSTEMD_CGROUP_CONTROLLER":%s: %s", p, strerror(-r));
 323                 return r;
 324         }
 325
 326         s->cgroup_path = p;
 327
 328         STRV_FOREACH(k, s->manager->controllers) {
 329                 if (s->leader > 0)
 330                         r = cg_create_and_attach(*k, p, s->leader);
 331                 else
 332                         r = cg_create(*k, p);
 333
 334                 if (r < 0)
 335                         log_warning("Failed to create cgroup %s:%s: %s", *k, p, strerror(-r));
 336         }
 337
 338         return 0;
 339 }
 340
 341 int session_start(Session *s) {
 342         int r;
 343
 344         assert(s);
 345         assert(s->user);
 346
 347         /* Create cgroup */
 348         r = session_create_cgroup(s);
 349         if (r < 0)
 350                 return r;
 351
 352         /* Create X11 symlink */
 353         session_link_x11_socket(s);
 354
 355         /* Save session data */
 356         session_save(s);
 357
 358         dual_timestamp_get(&s->timestamp);
 359
 360         return 0;
 361 }
 362
 363 static bool session_shall_kill(Session *s) {
 364         assert(s);
 365
 366         return s->kill_processes;
 367 }
 368
 369 static int session_kill_cgroup(Session *s) {
 370         int r;
 371         char **k;
 372
 373         assert(s);
 374
 375         if (!s->cgroup_path)
 376                 return 0;
 377
 378         cg_trim(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, false);
 379
 380         if (session_shall_kill(s)) {
 381
 382                 r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, true);
 383                 if (r < 0)
 384                         log_error("Failed to kill session cgroup: %s", strerror(-r));
 385
 386         } else {
 387                 r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, true);
 388                 if (r < 0)
 389                         log_error("Failed to check session cgroup: %s", strerror(-r));
 390                 else if (r > 0) {
 391                         r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path);
 392                         if (r < 0)
 393                                 log_error("Failed to delete session cgroup: %s", strerror(-r));
 394                 } else
 395                         r = -EBUSY;
 396         }
 397
 398         STRV_FOREACH(k, s->user->manager->controllers)
 399                 cg_trim(*k, s->cgroup_path, true);
 400
 401         free(s->cgroup_path);
 402         s->cgroup_path = NULL;
 403
 404         return r;
 405 }
 406
 407 static int session_unlink_x11_socket(Session *s) {
 408         char *t;
 409         int r;
 410
 411         assert(s);
 412         assert(s->user);
 413
 414         if (s->user->display != s)
 415                 return 0;
 416
 417         s->user->display = NULL;
 418
 419         t = strappend(s->user->runtime_path, "/display");
 420         if (!t) {
 421                 log_error("Out of memory");
 422                 return -ENOMEM;
 423         }
 424
 425         r = unlink(t);
 426         free(t);
 427
 428         return r < 0 ? -errno : 0;
 429 }
 430
 431 int session_stop(Session *s) {
 432         int r = 0, k;
 433
 434         assert(s);
 435
 436         /* Kill cgroup */
 437         k = session_kill_cgroup(s);
 438         if (k < 0)
 439                 r = k;
 440
 441         /* Remove X11 symlink */
 442         session_unlink_x11_socket(s);
 443
 444         unlink(s->state_file);
 445         session_add_to_gc_queue(s);
 446
 447         return r;
 448 }
 449
 450 bool session_is_active(Session *s) {
 451         assert(s);
 452
 453         if (!s->seat)
 454                 return true;
 455
 456         return s->seat->active == s;
 457 }
 458
 459 int session_check_gc(Session *s) {
 460         int r;
 461
 462         assert(s);
 463
 464         if (s->pipe_fd >= 0) {
 465
 466                 r = pipe_eof(s->pipe_fd);
 467                 if (r < 0)
 468                         return r;
 469
 470                 if (r == 0)
 471                         return 1;
 472         }
 473
 474         if (s->cgroup_path) {
 475
 476                 r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, false);
 477                 if (r < 0)
 478                         return r;
 479
 480                 if (r <= 0)
 481                         return 1;
 482         }
 483
 484         return 0;
 485 }
 486
 487 void session_add_to_gc_queue(Session *s) {
 488         assert(s);
 489
 490         if (s->in_gc_queue)
 491                 return;
 492
 493         LIST_PREPEND(Session, gc_queue, s->manager->session_gc_queue, s);
 494         s->in_gc_queue = true;
 495 }
 496
 497 static const char* const session_type_table[_SESSION_TYPE_MAX] = {
 498         [SESSION_TERMINAL] = "terminal",
 499         [SESSION_X11] = "x11"
 500 };
 501
 502 DEFINE_STRING_TABLE_LOOKUP(session_type, SessionType);