src/shared/clean-ipc.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <dirent.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <limits.h>
  24 #include <mqueue.h>
  25 #include <stdbool.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <sys/ipc.h>
  29 #include <sys/msg.h>
  30 #include <sys/sem.h>
  31 #include <sys/shm.h>
  32 #include <sys/stat.h>
  33 #include <unistd.h>
  34
  35 #include "clean-ipc.h"
  36 #include "dirent-util.h"
  37 #include "fd-util.h"
  38 #include "fileio.h"
  39 #include "format-util.h"
  40 #include "log.h"
  41 #include "macro.h"
  42 #include "string-util.h"
  43 #include "strv.h"
  44 #include "user-util.h"
  45
  46 static bool match_uid_gid(uid_t subject_uid, gid_t subject_gid, uid_t delete_uid, gid_t delete_gid) {
  47
  48         if (uid_is_valid(delete_uid) && subject_uid == delete_uid)
  49                 return true;
  50
  51         if (gid_is_valid(delete_gid) && subject_gid == delete_gid)
  52                 return true;
  53
  54         return false;
  55 }
  56
  57 static int clean_sysvipc_shm(uid_t delete_uid, gid_t delete_gid, bool rm) {
  58         _cleanup_fclose_ FILE *f = NULL;
  59         char line[LINE_MAX];
  60         bool first = true;
  61         int ret = 0;
  62
  63         f = fopen("/proc/sysvipc/shm", "re");
  64         if (!f) {
  65                 if (errno == ENOENT)
  66                         return 0;
  67
  68                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/shm: %m");
  69         }
  70
  71         FOREACH_LINE(line, f, goto fail) {
  72                 unsigned n_attached;
  73                 pid_t cpid, lpid;
  74                 uid_t uid, cuid;
  75                 gid_t gid, cgid;
  76                 int shmid;
  77
  78                 if (first) {
  79                         first = false;
  80                         continue;
  81                 }
  82
  83                 truncate_nl(line);
  84
  85                 if (sscanf(line, "%*i %i %*o %*u " PID_FMT " " PID_FMT " %u " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
  86                            &shmid, &cpid, &lpid, &n_attached, &uid, &gid, &cuid, &cgid) != 8)
  87                         continue;
  88
  89                 if (n_attached > 0)
  90                         continue;
  91
  92                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
  93                         continue;
  94
  95                 if (!rm)
  96                         return 1;
  97
  98                 if (shmctl(shmid, IPC_RMID, NULL) < 0) {
  99
 100                         /* Ignore entries that are already deleted */
 101                         if (IN_SET(errno, EIDRM, EINVAL))
 102                                 continue;
 103
 104                         ret = log_warning_errno(errno,
 105                                                 "Failed to remove SysV shared memory segment %i: %m",
 106                                                 shmid);
 107                 } else {
 108                         log_debug("Removed SysV shared memory segment %i.", shmid);
 109                         if (ret == 0)
 110                                 ret = 1;
 111                 }
 112         }
 113
 114         return ret;
 115
 116 fail:
 117         return log_warning_errno(errno, "Failed to read /proc/sysvipc/shm: %m");
 118 }
 119
 120 static int clean_sysvipc_sem(uid_t delete_uid, gid_t delete_gid, bool rm) {
 121         _cleanup_fclose_ FILE *f = NULL;
 122         char line[LINE_MAX];
 123         bool first = true;
 124         int ret = 0;
 125
 126         f = fopen("/proc/sysvipc/sem", "re");
 127         if (!f) {
 128                 if (errno == ENOENT)
 129                         return 0;
 130
 131                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/sem: %m");
 132         }
 133
 134         FOREACH_LINE(line, f, goto fail) {
 135                 uid_t uid, cuid;
 136                 gid_t gid, cgid;
 137                 int semid;
 138
 139                 if (first) {
 140                         first = false;
 141                         continue;
 142                 }
 143
 144                 truncate_nl(line);
 145
 146                 if (sscanf(line, "%*i %i %*o %*u " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
 147                            &semid, &uid, &gid, &cuid, &cgid) != 5)
 148                         continue;
 149
 150                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
 151                         continue;
 152
 153                 if (!rm)
 154                         return 1;
 155
 156                 if (semctl(semid, 0, IPC_RMID) < 0) {
 157
 158                         /* Ignore entries that are already deleted */
 159                         if (IN_SET(errno, EIDRM, EINVAL))
 160                                 continue;
 161
 162                         ret = log_warning_errno(errno,
 163                                                 "Failed to remove SysV semaphores object %i: %m",
 164                                                 semid);
 165                 } else {
 166                         log_debug("Removed SysV semaphore %i.", semid);
 167                         if (ret == 0)
 168                                 ret = 1;
 169                 }
 170         }
 171
 172         return ret;
 173
 174 fail:
 175         return log_warning_errno(errno, "Failed to read /proc/sysvipc/sem: %m");
 176 }
 177
 178 static int clean_sysvipc_msg(uid_t delete_uid, gid_t delete_gid, bool rm) {
 179         _cleanup_fclose_ FILE *f = NULL;
 180         char line[LINE_MAX];
 181         bool first = true;
 182         int ret = 0;
 183
 184         f = fopen("/proc/sysvipc/msg", "re");
 185         if (!f) {
 186                 if (errno == ENOENT)
 187                         return 0;
 188
 189                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/msg: %m");
 190         }
 191
 192         FOREACH_LINE(line, f, goto fail) {
 193                 uid_t uid, cuid;
 194                 gid_t gid, cgid;
 195                 pid_t cpid, lpid;
 196                 int msgid;
 197
 198                 if (first) {
 199                         first = false;
 200                         continue;
 201                 }
 202
 203                 truncate_nl(line);
 204
 205                 if (sscanf(line, "%*i %i %*o %*u %*u " PID_FMT " " PID_FMT " " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
 206                            &msgid, &cpid, &lpid, &uid, &gid, &cuid, &cgid) != 7)
 207                         continue;
 208
 209                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
 210                         continue;
 211
 212                 if (!rm)
 213                         return 1;
 214
 215                 if (msgctl(msgid, IPC_RMID, NULL) < 0) {
 216
 217                         /* Ignore entries that are already deleted */
 218                         if (IN_SET(errno, EIDRM, EINVAL))
 219                                 continue;
 220
 221                         ret = log_warning_errno(errno,
 222                                                 "Failed to remove SysV message queue %i: %m",
 223                                                 msgid);
 224                 } else {
 225                         log_debug("Removed SysV message queue %i.", msgid);
 226                         if (ret == 0)
 227                                 ret = 1;
 228                 }
 229         }
 230
 231         return ret;
 232
 233 fail:
 234         return log_warning_errno(errno, "Failed to read /proc/sysvipc/msg: %m");
 235 }
 236
 237 static int clean_posix_shm_internal(DIR *dir, uid_t uid, gid_t gid, bool rm) {
 238         struct dirent *de;
 239         int ret = 0, r;
 240
 241         assert(dir);
 242
 243         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 244                 struct stat st;
 245
 246                 if (dot_or_dot_dot(de->d_name))
 247                         continue;
 248
 249                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 250                         if (errno == ENOENT)
 251                                 continue;
 252
 253                         ret = log_warning_errno(errno, "Failed to stat() POSIX shared memory segment %s: %m", de->d_name);
 254                         continue;
 255                 }
 256
 257                 if (S_ISDIR(st.st_mode)) {
 258                         _cleanup_closedir_ DIR *kid;
 259
 260                         kid = xopendirat(dirfd(dir), de->d_name, O_NOFOLLOW|O_NOATIME);
 261                         if (!kid) {
 262                                 if (errno != ENOENT)
 263                                         ret = log_warning_errno(errno, "Failed to enter shared memory directory %s: %m", de->d_name);
 264                         } else {
 265                                 r = clean_posix_shm_internal(kid, uid, gid, rm);
 266                                 if (r < 0)
 267                                         ret = r;
 268                         }
 269
 270                         if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 271                                 continue;
 272
 273                         if (!rm)
 274                                 return 1;
 275
 276                         if (unlinkat(dirfd(dir), de->d_name, AT_REMOVEDIR) < 0) {
 277
 278                                 if (errno == ENOENT)
 279                                         continue;
 280
 281                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory directory %s: %m", de->d_name);
 282                         } else {
 283                                 log_debug("Removed POSIX shared memory directory %s", de->d_name);
 284                                 if (ret == 0)
 285                                         ret = 1;
 286                         }
 287                 } else {
 288
 289                         if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 290                                 continue;
 291
 292                         if (!rm)
 293                                 return 1;
 294
 295                         if (unlinkat(dirfd(dir), de->d_name, 0) < 0) {
 296
 297                                 if (errno == ENOENT)
 298                                         continue;
 299
 300                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory segment %s: %m", de->d_name);
 301                         } else {
 302                                 log_debug("Removed POSIX shared memory segment %s", de->d_name);
 303                                 if (ret == 0)
 304                                         ret = 1;
 305                         }
 306                 }
 307         }
 308
 309         return ret;
 310
 311 fail:
 312         return log_warning_errno(errno, "Failed to read /dev/shm: %m");
 313 }
 314
 315 static int clean_posix_shm(uid_t uid, gid_t gid, bool rm) {
 316         _cleanup_closedir_ DIR *dir = NULL;
 317
 318         dir = opendir("/dev/shm");
 319         if (!dir) {
 320                 if (errno == ENOENT)
 321                         return 0;
 322
 323                 return log_warning_errno(errno, "Failed to open /dev/shm: %m");
 324         }
 325
 326         return clean_posix_shm_internal(dir, uid, gid, rm);
 327 }
 328
 329 #if 0 /// UNNEEDED by elogind
 330 static int clean_posix_mq(uid_t uid, gid_t gid, bool rm) {
 331         _cleanup_closedir_ DIR *dir = NULL;
 332         struct dirent *de;
 333         int ret = 0;
 334
 335         dir = opendir("/dev/mqueue");
 336         if (!dir) {
 337                 if (errno == ENOENT)
 338                         return 0;
 339
 340                 return log_warning_errno(errno, "Failed to open /dev/mqueue: %m");
 341         }
 342
 343         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 344                 struct stat st;
 345                 char fn[1+strlen(de->d_name)+1];
 346
 347                 if (dot_or_dot_dot(de->d_name))
 348                         continue;
 349
 350                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 351                         if (errno == ENOENT)
 352                                 continue;
 353
 354                         ret = log_warning_errno(errno,
 355                                                 "Failed to stat() MQ segment %s: %m",
 356                                                 de->d_name);
 357                         continue;
 358                 }
 359
 360                 if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 361                         continue;
 362
 363                 if (!rm)
 364                         return 1;
 365
 366                 fn[0] = '/';
 367                 strcpy(fn+1, de->d_name);
 368
 369                 if (mq_unlink(fn) < 0) {
 370                         if (errno == ENOENT)
 371                                 continue;
 372
 373                         ret = log_warning_errno(errno,
 374                                                 "Failed to unlink POSIX message queue %s: %m",
 375                                                 fn);
 376                 } else {
 377                         log_debug("Removed POSIX message queue %s", fn);
 378                         if (ret == 0)
 379                                 ret = 1;
 380                 }
 381         }
 382
 383         return ret;
 384
 385 fail:
 386         return log_warning_errno(errno, "Failed to read /dev/mqueue: %m");
 387 }
 388 #endif // 0
 389
 390 int clean_ipc_internal(uid_t uid, gid_t gid, bool rm) {
 391         int ret = 0, r;
 392
 393         /* If 'rm' is true, clean all IPC objects owned by either the specified UID or the specified GID. Return the
 394          * last error encountered or == 0 if no matching IPC objects have been found or > 0 if matching IPC objects
 395          * have been found and have been removed.
 396          *
 397          * If 'rm' is false, just search for IPC objects owned by either the specified UID or the specified GID. In
 398          * this case we return < 0 on error, > 0 if we found a matching object, == 0 if we didn't.
 399          *
 400          * As special rule: if UID/GID is specified as root we'll silently not clean up things, and always claim that
 401          * there are IPC objects for it. */
 402
 403         if (uid == 0) {
 404                 if (!rm)
 405                         return 1;
 406
 407                 uid = UID_INVALID;
 408         }
 409         if (gid == 0) {
 410                 if (!rm)
 411                         return 1;
 412
 413                 gid = GID_INVALID;
 414         }
 415
 416         /* Anything to do? */
 417         if (!uid_is_valid(uid) && !gid_is_valid(gid))
 418                 return 0;
 419
 420         r = clean_sysvipc_shm(uid, gid, rm);
 421         if (r != 0) {
 422                 if (!rm)
 423                         return r;
 424                 if (ret == 0)
 425                         ret = r;
 426         }
 427
 428 #if 0 /// elogind does not use mq_open anywhere
 429 #endif // 0
 430         r = clean_sysvipc_sem(uid, gid, rm);
 431         if (r != 0) {
 432                 if (!rm)
 433                         return r;
 434                 if (ret == 0)
 435                         ret = r;
 436         }
 437
 438         r = clean_sysvipc_msg(uid, gid, rm);
 439         if (r != 0) {
 440                 if (!rm)
 441                         return r;
 442                 if (ret == 0)
 443                         ret = r;
 444         }
 445
 446         r = clean_posix_shm(uid, gid, rm);
 447         if (r != 0) {
 448                 if (!rm)
 449                         return r;
 450                 if (ret == 0)
 451                         ret = r;
 452         }
 453
 454         r = clean_posix_mq(uid, gid, rm);
 455         if (r != 0) {
 456                 if (!rm)
 457                         return r;
 458                 if (ret == 0)
 459                         ret = r;
 460         }
 461
 462         return ret;
 463 }
 464
 465 int clean_ipc_by_uid(uid_t uid) {
 466         return clean_ipc_internal(uid, GID_INVALID, true);
 467 }
 468
 469 #if 0 /// UNNEEDED by elogind
 470 int clean_ipc_by_gid(gid_t gid) {
 471         return clean_ipc_internal(UID_INVALID, gid, true);
 472 }
 473 #endif // 0