src/shared/clean-ipc.c

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