src/shared/clean-ipc.c

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