src/pam-module.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 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 <fcntl.h>
  24 #include <sys/file.h>
  25 #include <pwd.h>
  26 #include <endian.h>
  27 #include <sys/capability.h>
  28
  29 #include <security/pam_modules.h>
  30 #include <security/_pam_macros.h>
  31 #include <security/pam_modutil.h>
  32 #include <security/pam_ext.h>
  33 #include <security/pam_misc.h>
  34
  35 #include "util.h"
  36 #include "cgroup-util.h"
  37 #include "macro.h"
  38 #include "sd-daemon.h"
  39 #include "strv.h"
  40
  41 static int parse_argv(pam_handle_t *handle,
  42                       int argc, const char **argv,
  43                       bool *create_session,
  44                       bool *kill_session,
  45                       bool *kill_user,
  46                       char ***controllers,
  47                       char ***reset_controllers,
  48                       char ***kill_only_users,
  49                       char ***kill_exclude_users,
  50                       bool *debug) {
  51
  52         unsigned i;
  53         bool reset_controller_set = false;
  54         bool kill_exclude_users_set = false;
  55
  56         assert(argc >= 0);
  57         assert(argc == 0 || argv);
  58
  59         for (i = 0; i < (unsigned) argc; i++) {
  60                 int k;
  61
  62                 if (startswith(argv[i], "create-session=")) {
  63                         if ((k = parse_boolean(argv[i] + 15)) < 0) {
  64                                 pam_syslog(handle, LOG_ERR, "Failed to parse create-session= argument.");
  65                                 return k;
  66                         }
  67
  68                         if (create_session)
  69                                 *create_session = k;
  70
  71                 } else if (startswith(argv[i], "kill-session=")) {
  72                         if ((k = parse_boolean(argv[i] + 13)) < 0) {
  73                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
  74                                 return k;
  75                         }
  76
  77                         if (kill_session)
  78                                 *kill_session = k;
  79
  80                 } else if (startswith(argv[i], "kill-user=")) {
  81                         if ((k = parse_boolean(argv[i] + 10)) < 0) {
  82                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-user= argument.");
  83                                 return k;
  84                         }
  85
  86                         if (kill_user)
  87                                 *kill_user = k;
  88
  89                 } else if (startswith(argv[i], "controllers=")) {
  90
  91                         if (controllers) {
  92                                 char **l;
  93
  94                                 if (!(l = strv_split(argv[i] + 12, ","))) {
  95                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
  96                                         return -ENOMEM;
  97                                 }
  98
  99                                 strv_free(*controllers);
 100                                 *controllers = l;
 101                         }
 102
 103                 } else if (startswith(argv[i], "reset-controllers=")) {
 104
 105                         if (reset_controllers) {
 106                                 char **l;
 107
 108                                 if (!(l = strv_split(argv[i] + 18, ","))) {
 109                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 110                                         return -ENOMEM;
 111                                 }
 112
 113                                 strv_free(*reset_controllers);
 114                                 *reset_controllers = l;
 115                         }
 116
 117                         reset_controller_set = true;
 118
 119                 } else if (startswith(argv[i], "kill-only-users=")) {
 120
 121                         if (kill_only_users) {
 122                                 char **l;
 123
 124                                 if (!(l = strv_split(argv[i] + 16, ","))) {
 125                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 126                                         return -ENOMEM;
 127                                 }
 128
 129                                 strv_free(*kill_only_users);
 130                                 *kill_only_users = l;
 131                         }
 132
 133                 } else if (startswith(argv[i], "kill-exclude-users=")) {
 134
 135                         if (kill_exclude_users) {
 136                                 char **l;
 137
 138                                 if (!(l = strv_split(argv[i] + 19, ","))) {
 139                                         pam_syslog(handle, LOG_ERR, "Out of memory.");
 140                                         return -ENOMEM;
 141                                 }
 142
 143                                 strv_free(*kill_exclude_users);
 144                                 *kill_exclude_users = l;
 145                         }
 146
 147                         kill_exclude_users_set = true;
 148
 149                 } else if (startswith(argv[i], "debug=")) {
 150                         if ((k = parse_boolean(argv[i] + 6)) < 0) {
 151                                 pam_syslog(handle, LOG_ERR, "Failed to parse debug= argument.");
 152                                 return k;
 153                         }
 154
 155                         if (debug)
 156                                 *debug = k;
 157
 158                 } else {
 159                         pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
 160                         return -EINVAL;
 161                 }
 162         }
 163
 164         if (!reset_controller_set && reset_controllers) {
 165                 char **l;
 166
 167                 if (!(l = strv_new("cpu", NULL))) {
 168                         pam_syslog(handle, LOG_ERR, "Out of memory");
 169                         return -ENOMEM;
 170                 }
 171
 172                 *reset_controllers = l;
 173         }
 174
 175         if (controllers)
 176                 strv_remove(*controllers, "name=systemd");
 177
 178         if (reset_controllers)
 179                 strv_remove(*reset_controllers, "name=systemd");
 180
 181         if (kill_session && *kill_session && kill_user)
 182                 *kill_user = true;
 183
 184         if (!kill_exclude_users_set && kill_exclude_users) {
 185                 char **l;
 186
 187                 if (!(l = strv_new("root", NULL))) {
 188                         pam_syslog(handle, LOG_ERR, "Out of memory");
 189                         return -ENOMEM;
 190                 }
 191
 192                 *kill_exclude_users = l;
 193         }
 194
 195         return 0;
 196 }
 197
 198 static int open_file_and_lock(const char *fn) {
 199         int fd;
 200
 201         assert(fn);
 202
 203         if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
 204                 return -errno;
 205
 206         /* The BSD socket semantics are a lot nicer than those of
 207          * POSIX locks. Which is why we use flock() here. BSD locking
 208          * does not work across NFS which however is not needed here
 209          * as the filesystems in question should be local, and only
 210          * locally accessible, and most likely even tmpfs. */
 211
 212         if (flock(fd, LOCK_EX) < 0) {
 213                 close_nointr_nofail(fd);
 214                 return -errno;
 215         }
 216
 217         return fd;
 218 }
 219
 220 enum {
 221         SESSION_ID_AUDIT = 'a',
 222         SESSION_ID_COUNTER = 'c',
 223         SESSION_ID_RANDOM = 'r'
 224 };
 225
 226 static uint64_t get_session_id(int *mode) {
 227         char *s;
 228         int fd;
 229
 230         assert(mode);
 231
 232         /* First attempt: let's use the session ID of the audit
 233          * system, if it is available. */
 234         if (have_effective_cap(CAP_AUDIT_CONTROL) > 0)
 235                 if (read_one_line_file("/proc/self/sessionid", &s) >= 0) {
 236                         uint32_t u;
 237                         int r;
 238
 239                         r = safe_atou32(s, &u);
 240                         free(s);
 241
 242                         if (r >= 0 && u != (uint32_t) -1 && u > 0) {
 243                                 *mode = SESSION_ID_AUDIT;
 244                                 return (uint64_t) u;
 245                         }
 246                 }
 247
 248         /* Second attempt, use our own counter. */
 249         if ((fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-session")) >= 0) {
 250                 uint64_t counter;
 251                 ssize_t r;
 252
 253                 /* We do a bit of endianess swapping here, just to be
 254                  * sure. /run should be machine specific anyway, and
 255                  * even mounted from tmpfs, so this byteswapping
 256                  * should really not be necessary. But then again, you
 257                  * never know, so let's avoid any risk. */
 258
 259                 if (loop_read(fd, &counter, sizeof(counter), false) != sizeof(counter))
 260                         counter = 1;
 261                 else
 262                         counter = le64toh(counter) + 1;
 263
 264                 if (lseek(fd, 0, SEEK_SET) == 0) {
 265                         uint64_t swapped = htole64(counter);
 266
 267                         r = loop_write(fd, &swapped, sizeof(swapped), false);
 268
 269                         if (r != sizeof(swapped))
 270                                 r = -EIO;
 271                 } else
 272                         r = -errno;
 273
 274                 close_nointr_nofail(fd);
 275
 276                 if (r >= 0) {
 277                         *mode = SESSION_ID_COUNTER;
 278                         return counter;
 279                 }
 280         }
 281
 282         *mode = SESSION_ID_RANDOM;
 283
 284         /* Last attempt, pick a random value */
 285         return (uint64_t) random_ull();
 286 }
 287
 288 static int get_user_data(
 289                 pam_handle_t *handle,
 290                 const char **ret_username,
 291                 struct passwd **ret_pw) {
 292
 293         const char *username = NULL;
 294         struct passwd *pw = NULL;
 295         int r;
 296         bool have_loginuid = false;
 297         char *s;
 298
 299         assert(handle);
 300         assert(ret_username);
 301         assert(ret_pw);
 302
 303         if (have_effective_cap(CAP_AUDIT_CONTROL) > 0) {
 304                 /* Only use audit login uid if we are executed with
 305                  * sufficient capabilities so that pam_loginuid could
 306                  * do its job. If we are lacking the CAP_AUDIT_CONTROL
 307                  * capabality we most likely are being run in a
 308                  * container and /proc/self/loginuid is useless since
 309                  * it probably contains a uid of the host system. */
 310
 311                 if (read_one_line_file("/proc/self/loginuid", &s) >= 0) {
 312                         uint32_t u;
 313
 314                         r = safe_atou32(s, &u);
 315                         free(s);
 316
 317                         if (r >= 0 && u != (uint32_t) -1 && u > 0) {
 318                                 have_loginuid = true;
 319                                 pw = pam_modutil_getpwuid(handle, u);
 320                         }
 321                 }
 322         }
 323
 324         if (!have_loginuid) {
 325                 if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
 326                         pam_syslog(handle, LOG_ERR, "Failed to get user name.");
 327                         return r;
 328                 }
 329
 330                 if (!username || !*username) {
 331                         pam_syslog(handle, LOG_ERR, "User name not valid.");
 332                         return PAM_AUTH_ERR;
 333                 }
 334
 335                 pw = pam_modutil_getpwnam(handle, username);
 336         }
 337
 338         if (!pw) {
 339                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
 340                 return PAM_USER_UNKNOWN;
 341         }
 342
 343         *ret_pw = pw;
 344         *ret_username = username ? username : pw->pw_name;
 345
 346         return PAM_SUCCESS;
 347 }
 348
 349 static int create_user_group(
 350                 pam_handle_t *handle,
 351                 const char *controller,
 352                 const char *group,
 353                 struct passwd *pw,
 354                 bool attach,
 355                 bool remember) {
 356
 357         int r;
 358
 359         assert(handle);
 360         assert(group);
 361
 362         if (attach)
 363                 r = cg_create_and_attach(controller, group, 0);
 364         else
 365                 r = cg_create(controller, group);
 366
 367         if (r < 0) {
 368                 pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
 369                 return PAM_SESSION_ERR;
 370         }
 371
 372         if (r > 0 && remember) {
 373                 /* Remember that it was us who created this group, and
 374                  * that hence we need to remove it too. This is a
 375                  * protection against removing the cgroup when run
 376                  * recursively. */
 377                 if ((r = pam_set_data(handle, "systemd.created", INT_TO_PTR(1), NULL)) != PAM_SUCCESS) {
 378                         pam_syslog(handle, LOG_ERR, "Failed to install created variable.");
 379                         return r;
 380                 }
 381         }
 382
 383         if ((r = cg_set_task_access(controller, group, 0644, pw->pw_uid, pw->pw_gid)) < 0 ||
 384             (r = cg_set_group_access(controller, group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
 385                 pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
 386                 return PAM_SESSION_ERR;
 387         }
 388
 389         return PAM_SUCCESS;
 390 }
 391
 392 static int reset_group(
 393                 pam_handle_t *handle,
 394                 const char *controller) {
 395
 396         int r;
 397
 398         assert(handle);
 399
 400         if ((r = cg_attach(controller, "/", 0)) < 0) {
 401                 pam_syslog(handle, LOG_ERR, "Failed to reset cgroup for controller %s: %s", controller, strerror(-r));
 402                 return PAM_SESSION_ERR;
 403         }
 404
 405         return PAM_SUCCESS;
 406 }
 407
 408 _public_ PAM_EXTERN int pam_sm_open_session(
 409                 pam_handle_t *handle,
 410                 int flags,
 411                 int argc, const char **argv) {
 412
 413         const char *username = NULL;
 414         struct passwd *pw;
 415         int r;
 416         char *buf = NULL;
 417         int lock_fd = -1;
 418         bool create_session = true;
 419         bool debug = false;
 420         char **controllers = NULL, **reset_controllers = NULL, **c;
 421         char *cgroup_user_tree = NULL;
 422
 423         assert(handle);
 424
 425         /* pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing"); */
 426
 427         /* Make this a NOP on non-systemd systems */
 428         if (sd_booted() <= 0)
 429                 return PAM_SUCCESS;
 430
 431         if (parse_argv(handle,
 432                        argc, argv,
 433                        &create_session, NULL, NULL,
 434                        &controllers, &reset_controllers,
 435                        NULL, NULL, &debug) < 0)
 436                 return PAM_SESSION_ERR;
 437
 438         if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
 439                 goto finish;
 440
 441         if ((r = cg_get_user_path(&cgroup_user_tree)) < 0) {
 442                 pam_syslog(handle, LOG_ERR, "Failed to determine user cgroup tree: %s", strerror(-r));
 443                 r = PAM_SYSTEM_ERR;
 444                 goto finish;
 445         }
 446
 447         if (safe_mkdir(RUNTIME_DIR "/user", 0755, 0, 0) < 0) {
 448                 pam_syslog(handle, LOG_ERR, "Failed to create runtime directory: %m");
 449                 r = PAM_SYSTEM_ERR;
 450                 goto finish;
 451         }
 452
 453         if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
 454                 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
 455                 r = PAM_SYSTEM_ERR;
 456                 goto finish;
 457         }
 458
 459         /* Create /run/user/$USER */
 460         free(buf);
 461         if (asprintf(&buf, RUNTIME_DIR "/user/%s", username) < 0) {
 462                 r = PAM_BUF_ERR;
 463                 goto finish;
 464         }
 465
 466         if (safe_mkdir(buf, 0700, pw->pw_uid, pw->pw_gid) < 0) {
 467                 pam_syslog(handle, LOG_WARNING, "Failed to create runtime directory: %m");
 468                 r = PAM_SYSTEM_ERR;
 469                 goto finish;
 470         } else if ((r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", buf, 0)) != PAM_SUCCESS) {
 471                 pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
 472                 goto finish;
 473         }
 474
 475         free(buf);
 476         buf = NULL;
 477
 478         if (create_session) {
 479                 const char *id;
 480
 481                 /* Reuse or create XDG session ID */
 482                 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
 483                         int mode;
 484
 485                         if (asprintf(&buf, "%llux", (unsigned long long) get_session_id(&mode)) < 0) {
 486                                 r = PAM_BUF_ERR;
 487                                 goto finish;
 488                         }
 489
 490                         /* To avoid id clashes we add the session id
 491                          * source to our session ids. Note that the
 492                          * session id source might change during
 493                          * runtime, because a filesystem became
 494                          * writable or the system reconfigured. */
 495                         buf[strlen(buf)-1] =
 496                                 mode != SESSION_ID_AUDIT ? (char) mode : 0;
 497
 498                         if ((r = pam_misc_setenv(handle, "XDG_SESSION_ID", buf, 0)) != PAM_SUCCESS) {
 499                                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
 500                                 goto finish;
 501                         }
 502
 503                         if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
 504                                 pam_syslog(handle, LOG_ERR, "Failed to get session id.");
 505                                 r = PAM_SESSION_ERR;
 506                                 goto finish;
 507                         }
 508                 }
 509
 510                 r = asprintf(&buf, "%s/%s/%s", cgroup_user_tree, username, id);
 511         } else
 512                 r = asprintf(&buf, "%s/%s/master", cgroup_user_tree, username);
 513
 514         if (r < 0) {
 515                 r = PAM_BUF_ERR;
 516                 goto finish;
 517         }
 518
 519         if (debug)
 520                 pam_syslog(handle, LOG_DEBUG, "Moving new user session for %s into control group %s.", username, buf);
 521
 522         if ((r = create_user_group(handle, SYSTEMD_CGROUP_CONTROLLER, buf, pw, true, true)) != PAM_SUCCESS)
 523                 goto finish;
 524
 525         /* The additional controllers don't really matter, so we
 526          * ignore the return value */
 527         STRV_FOREACH(c, controllers)
 528                 create_user_group(handle, *c, buf, pw, true, false);
 529
 530         STRV_FOREACH(c, reset_controllers)
 531                 reset_group(handle, *c);
 532
 533         r = PAM_SUCCESS;
 534
 535 finish:
 536         free(buf);
 537
 538         if (lock_fd >= 0)
 539                 close_nointr_nofail(lock_fd);
 540
 541         strv_free(controllers);
 542         strv_free(reset_controllers);
 543
 544         free(cgroup_user_tree);
 545
 546         return r;
 547 }
 548
 549 static int session_remains(pam_handle_t *handle, const char *user_path) {
 550         int r;
 551         bool remains = false;
 552         DIR *d;
 553         char *subgroup;
 554
 555         if ((r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, user_path, &d)) < 0)
 556                 return r;
 557
 558         while ((r = cg_read_subgroup(d, &subgroup)) > 0) {
 559
 560                 remains = !streq(subgroup, "master");
 561                 free(subgroup);
 562
 563                 if (remains)
 564                         break;
 565         }
 566
 567         closedir(d);
 568
 569         if (r < 0)
 570                 return r;
 571
 572         return !!remains;
 573 }
 574
 575 static bool check_user_lists(
 576                 pam_handle_t *handle,
 577                 uid_t uid,
 578                 char **kill_only_users,
 579                 char **kill_exclude_users) {
 580
 581         const char *name = NULL;
 582         char **l;
 583
 584         assert(handle);
 585
 586         if (uid == 0)
 587                 name = "root"; /* Avoid obvious NSS requests, to suppress network traffic */
 588         else {
 589                 struct passwd *pw;
 590
 591                 if ((pw = pam_modutil_getpwuid(handle, uid)))
 592                         name = pw->pw_name;
 593         }
 594
 595         STRV_FOREACH(l, kill_exclude_users) {
 596                 uint32_t id;
 597
 598                 if (safe_atou32(*l, &id) >= 0)
 599                         if ((uid_t) id == uid)
 600                                 return false;
 601
 602                 if (name && streq(name, *l))
 603                         return false;
 604         }
 605
 606         if (strv_isempty(kill_only_users))
 607                 return true;
 608
 609         STRV_FOREACH(l, kill_only_users) {
 610                 uint32_t id;
 611
 612                 if (safe_atou32(*l, &id) >= 0)
 613                         if ((uid_t) id == uid)
 614                                 return true;
 615
 616                 if (name && streq(name, *l))
 617                         return true;
 618         }
 619
 620         return false;
 621 }
 622
 623 _public_ PAM_EXTERN int pam_sm_close_session(
 624                 pam_handle_t *handle,
 625                 int flags,
 626                 int argc, const char **argv) {
 627
 628         const char *username = NULL;
 629         bool kill_session = false;
 630         bool kill_user = false;
 631         bool debug = false;
 632         int lock_fd = -1, r;
 633         char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
 634         const char *id;
 635         struct passwd *pw;
 636         const void *created = NULL;
 637         char **controllers = NULL, **c, **kill_only_users = NULL, **kill_exclude_users = NULL;
 638         char *cgroup_user_tree = NULL;
 639
 640         assert(handle);
 641
 642         /* Make this a NOP on non-systemd systems */
 643         if (sd_booted() <= 0)
 644                 return PAM_SUCCESS;
 645
 646         if (parse_argv(handle,
 647                        argc, argv,
 648                        NULL, &kill_session, &kill_user,
 649                        &controllers, NULL,
 650                        &kill_only_users, &kill_exclude_users, &debug) < 0)
 651                 return PAM_SESSION_ERR;
 652
 653         if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
 654                 goto finish;
 655
 656         if ((r = cg_get_user_path(&cgroup_user_tree)) < 0) {
 657                 pam_syslog(handle, LOG_ERR, "Failed to determine user cgroup tree: %s", strerror(-r));
 658                 r = PAM_SYSTEM_ERR;
 659                 goto finish;
 660         }
 661
 662         if ((lock_fd = open_file_and_lock(RUNTIME_DIR "/user/.pam-systemd-lock")) < 0) {
 663                 pam_syslog(handle, LOG_ERR, "Failed to lock runtime directory: %m");
 664                 r = PAM_SYSTEM_ERR;
 665                 goto finish;
 666         }
 667
 668         /* We are probably still in some session/user dir. Move ourselves out of the way as first step */
 669         if ((r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, cgroup_user_tree, 0)) < 0)
 670                 pam_syslog(handle, LOG_ERR, "Failed to move us away: %s", strerror(-r));
 671
 672         STRV_FOREACH(c, controllers)
 673                 if ((r = cg_attach(*c, cgroup_user_tree, 0)) < 0)
 674                         pam_syslog(handle, LOG_ERR, "Failed to move us away in %s hierarchy: %s", *c, strerror(-r));
 675
 676         if (asprintf(&user_path, "%s/%s", cgroup_user_tree, username) < 0) {
 677                 r = PAM_BUF_ERR;
 678                 goto finish;
 679         }
 680
 681         pam_get_data(handle, "systemd.created", &created);
 682
 683         if ((id = pam_getenv(handle, "XDG_SESSION_ID")) && created) {
 684
 685                 if (asprintf(&session_path, "%s/%s/%s", cgroup_user_tree, username, id) < 0 ||
 686                     asprintf(&nosession_path, "%s/%s/master", cgroup_user_tree, username) < 0) {
 687                         r = PAM_BUF_ERR;
 688                         goto finish;
 689                 }
 690
 691                 if (kill_session && check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users))  {
 692                         if (debug)
 693                                 pam_syslog(handle, LOG_DEBUG, "Killing remaining processes of user session %s of %s.", id, username);
 694
 695                         /* Kill processes in session cgroup, and delete it */
 696                         if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, session_path, true)) < 0)
 697                                 pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
 698                 } else {
 699                         if (debug)
 700                                 pam_syslog(handle, LOG_DEBUG, "Moving remaining processes of user session %s of %s into control group %s.", id, username, nosession_path);
 701
 702                         /* Migrate processes from session to user
 703                          * cgroup. First, try to create the user group
 704                          * in case it doesn't exist yet. Also, delete
 705                          * the session group. */
 706                         create_user_group(handle, SYSTEMD_CGROUP_CONTROLLER, nosession_path, pw, false, false);
 707
 708                         if ((r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, session_path, nosession_path, false, true)) < 0)
 709                                 pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
 710                 }
 711
 712                 STRV_FOREACH(c, controllers) {
 713                         create_user_group(handle, *c, nosession_path, pw, false, false);
 714
 715                         if ((r = cg_migrate_recursive(*c, session_path, nosession_path, false, true)) < 0)
 716                                 pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup in hierarchy %s: %s", *c, strerror(-r));
 717                 }
 718         }
 719
 720         /* GC user tree */
 721         cg_trim(SYSTEMD_CGROUP_CONTROLLER, user_path, false);
 722
 723         if ((r = session_remains(handle, user_path)) < 0)
 724                 pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
 725
 726         /* Kill user processes not attached to any session */
 727         if (kill_user && r == 0 && check_user_lists(handle, pw->pw_uid, kill_only_users, kill_exclude_users)) {
 728
 729                 /* Kill user cgroup */
 730                 if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
 731                         pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
 732         } else {
 733
 734                 if ((r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
 735                         pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
 736
 737                 /* Remove user cgroup */
 738                 if (r > 0) {
 739                         if ((r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, user_path)) < 0)
 740                                 pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
 741
 742                 /* If we managed to find somebody, don't cleanup the cgroup. */
 743                 } else if (r == 0)
 744                         r = -EBUSY;
 745         }
 746
 747         STRV_FOREACH(c, controllers)
 748                 cg_trim(*c, user_path, true);
 749
 750         if (r >= 0) {
 751                 const char *runtime_dir;
 752
 753                 if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
 754                         if ((r = rm_rf(runtime_dir, false, true)) < 0)
 755                                 pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
 756         }
 757
 758         /* pam_syslog(handle, LOG_DEBUG, "pam-systemd done"); */
 759
 760         r = PAM_SUCCESS;
 761
 762 finish:
 763         if (lock_fd >= 0)
 764                 close_nointr_nofail(lock_fd);
 765
 766         free(session_path);
 767         free(nosession_path);
 768         free(user_path);
 769
 770         strv_free(controllers);
 771         strv_free(kill_exclude_users);
 772         strv_free(kill_only_users);
 773
 774         free(cgroup_user_tree);
 775
 776         return r;
 777 }