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         bool first = true;
  43         int ret = 0, r;
  44
  45         f = fopen("/proc/sysvipc/shm", "re");
  46         if (!f) {
  47                 if (errno == ENOENT)
  48                         return 0;
  49
  50                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/shm: %m");
  51         }
  52
  53         for (;;) {
  54                 _cleanup_free_ char *line = NULL;
  55                 unsigned n_attached;
  56                 pid_t cpid, lpid;
  57                 uid_t uid, cuid;
  58                 gid_t gid, cgid;
  59                 int shmid;
  60
  61                 r = read_line(f, LONG_LINE_MAX, &line);
  62                 if (r < 0)
  63                         return log_warning_errno(errno, "Failed to read /proc/sysvipc/shm: %m");
  64                 if (r == 0)
  65                         break;
  66
  67                 if (first) {
  68                         first = false;
  69                         continue;
  70                 }
  71
  72                 if (sscanf(line, "%*i %i %*o %*u " PID_FMT " " PID_FMT " %u " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
  73                            &shmid, &cpid, &lpid, &n_attached, &uid, &gid, &cuid, &cgid) != 8)
  74                         continue;
  75
  76                 if (n_attached > 0)
  77                         continue;
  78
  79                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
  80                         continue;
  81
  82                 if (!rm)
  83                         return 1;
  84
  85                 if (shmctl(shmid, IPC_RMID, NULL) < 0) {
  86
  87                         /* Ignore entries that are already deleted */
  88                         if (IN_SET(errno, EIDRM, EINVAL))
  89                                 continue;
  90
  91                         ret = log_warning_errno(errno,
  92                                                 "Failed to remove SysV shared memory segment %i: %m",
  93                                                 shmid);
  94                 } else {
  95                         log_debug("Removed SysV shared memory segment %i.", shmid);
  96                         if (ret == 0)
  97                                 ret = 1;
  98                 }
  99         }
 100
 101         return ret;
 102 }
 103
 104 static int clean_sysvipc_sem(uid_t delete_uid, gid_t delete_gid, bool rm) {
 105         _cleanup_fclose_ FILE *f = NULL;
 106         bool first = true;
 107         int ret = 0, r;
 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         for (;;) {
 118                 _cleanup_free_ char *line = NULL;
 119                 uid_t uid, cuid;
 120                 gid_t gid, cgid;
 121                 int semid;
 122
 123                 r = read_line(f, LONG_LINE_MAX, &line);
 124                 if (r < 0)
 125                         return log_warning_errno(r, "Failed to read /proc/sysvipc/sem: %m");
 126                 if (r == 0)
 127                         break;
 128
 129                 if (first) {
 130                         first = false;
 131                         continue;
 132                 }
 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
 163 static int clean_sysvipc_msg(uid_t delete_uid, gid_t delete_gid, bool rm) {
 164         _cleanup_fclose_ FILE *f = NULL;
 165         bool first = true;
 166         int ret = 0, r;
 167
 168         f = fopen("/proc/sysvipc/msg", "re");
 169         if (!f) {
 170                 if (errno == ENOENT)
 171                         return 0;
 172
 173                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/msg: %m");
 174         }
 175
 176         for (;;) {
 177                 _cleanup_free_ char *line = NULL;
 178                 uid_t uid, cuid;
 179                 gid_t gid, cgid;
 180                 pid_t cpid, lpid;
 181                 int msgid;
 182
 183                 r = read_line(f, LONG_LINE_MAX, &line);
 184                 if (r < 0)
 185                         return log_warning_errno(r, "Failed to read /proc/sysvipc/msg: %m");
 186                 if (r == 0)
 187                         break;
 188
 189                 if (first) {
 190                         first = false;
 191                         continue;
 192                 }
 193
 194                 if (sscanf(line, "%*i %i %*o %*u %*u " PID_FMT " " PID_FMT " " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
 195                            &msgid, &cpid, &lpid, &uid, &gid, &cuid, &cgid) != 7)
 196                         continue;
 197
 198                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
 199                         continue;
 200
 201                 if (!rm)
 202                         return 1;
 203
 204                 if (msgctl(msgid, IPC_RMID, NULL) < 0) {
 205
 206                         /* Ignore entries that are already deleted */
 207                         if (IN_SET(errno, EIDRM, EINVAL))
 208                                 continue;
 209
 210                         ret = log_warning_errno(errno,
 211                                                 "Failed to remove SysV message queue %i: %m",
 212                                                 msgid);
 213                 } else {
 214                         log_debug("Removed SysV message queue %i.", msgid);
 215                         if (ret == 0)
 216                                 ret = 1;
 217                 }
 218         }
 219
 220         return ret;
 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 static int clean_posix_mq(uid_t uid, gid_t gid, bool rm) {
 316         _cleanup_closedir_ DIR *dir = NULL;
 317         struct dirent *de;
 318         int ret = 0;
 319
 320         dir = opendir("/dev/mqueue");
 321         if (!dir) {
 322                 if (errno == ENOENT)
 323                         return 0;
 324
 325                 return log_warning_errno(errno, "Failed to open /dev/mqueue: %m");
 326         }
 327
 328         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 329                 struct stat st;
 330                 char fn[1+strlen(de->d_name)+1];
 331
 332                 if (dot_or_dot_dot(de->d_name))
 333                         continue;
 334
 335                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 336                         if (errno == ENOENT)
 337                                 continue;
 338
 339                         ret = log_warning_errno(errno,
 340                                                 "Failed to stat() MQ segment %s: %m",
 341                                                 de->d_name);
 342                         continue;
 343                 }
 344
 345                 if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 346                         continue;
 347
 348                 if (!rm)
 349                         return 1;
 350
 351                 fn[0] = '/';
 352                 strcpy(fn+1, de->d_name);
 353
 354                 if (mq_unlink(fn) < 0) {
 355                         if (errno == ENOENT)
 356                                 continue;
 357
 358                         ret = log_warning_errno(errno,
 359                                                 "Failed to unlink POSIX message queue %s: %m",
 360                                                 fn);
 361                 } else {
 362                         log_debug("Removed POSIX message queue %s", fn);
 363                         if (ret == 0)
 364                                 ret = 1;
 365                 }
 366         }
 367
 368         return ret;
 369
 370 fail:
 371         return log_warning_errno(errno, "Failed to read /dev/mqueue: %m");
 372 }
 373
 374 int clean_ipc_internal(uid_t uid, gid_t gid, bool rm) {
 375         int ret = 0, r;
 376
 377         /* If 'rm' is true, clean all IPC objects owned by either the specified UID or the specified GID. Return the
 378          * last error encountered or == 0 if no matching IPC objects have been found or > 0 if matching IPC objects
 379          * have been found and have been removed.
 380          *
 381          * If 'rm' is false, just search for IPC objects owned by either the specified UID or the specified GID. In
 382          * this case we return < 0 on error, > 0 if we found a matching object, == 0 if we didn't.
 383          *
 384          * As special rule: if UID/GID is specified as root we'll silently not clean up things, and always claim that
 385          * there are IPC objects for it. */
 386
 387         if (uid == 0) {
 388                 if (!rm)
 389                         return 1;
 390
 391                 uid = UID_INVALID;
 392         }
 393         if (gid == 0) {
 394                 if (!rm)
 395                         return 1;
 396
 397                 gid = GID_INVALID;
 398         }
 399
 400         /* Anything to do? */
 401         if (!uid_is_valid(uid) && !gid_is_valid(gid))
 402                 return 0;
 403
 404         r = clean_sysvipc_shm(uid, gid, rm);
 405         if (r != 0) {
 406                 if (!rm)
 407                         return r;
 408                 if (ret == 0)
 409                         ret = r;
 410         }
 411
 412         r = clean_sysvipc_sem(uid, gid, rm);
 413         if (r != 0) {
 414                 if (!rm)
 415                         return r;
 416                 if (ret == 0)
 417                         ret = r;
 418         }
 419
 420         r = clean_sysvipc_msg(uid, gid, rm);
 421         if (r != 0) {
 422                 if (!rm)
 423                         return r;
 424                 if (ret == 0)
 425                         ret = r;
 426         }
 427
 428         r = clean_posix_shm(uid, gid, rm);
 429         if (r != 0) {
 430                 if (!rm)
 431                         return r;
 432                 if (ret == 0)
 433                         ret = r;
 434         }
 435
 436         r = clean_posix_mq(uid, gid, rm);
 437         if (r != 0) {
 438                 if (!rm)
 439                         return r;
 440                 if (ret == 0)
 441                         ret = r;
 442         }
 443
 444         return ret;
 445 }
 446
 447 int clean_ipc_by_uid(uid_t uid) {
 448         return clean_ipc_internal(uid, GID_INVALID, true);
 449 }
 450
 451 int clean_ipc_by_gid(gid_t gid) {
 452         return clean_ipc_internal(UID_INVALID, gid, true);
 453 }