src/shared/clean-ipc.c

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