src/shared/clean-ipc.c

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