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(const char *dirname, 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/%s: %m",
 238                                                 dirname, de->d_name);
 239                         continue;
 240                 }
 241
 242                 if (S_ISDIR(st.st_mode)) {
 243                         _cleanup_closedir_ DIR *kid;
 244
 245                         kid = xopendirat(dirfd(dir), de->d_name, O_NOFOLLOW|O_NOATIME);
 246                         if (!kid) {
 247                                 if (errno != ENOENT)
 248                                         ret = log_warning_errno(errno, "Failed to enter shared memory directory %s/%s: %m",
 249                                                                 dirname, de->d_name);
 250                         } else {
 251                                 r = clean_posix_shm_internal(de->d_name, 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/%s: %m",
 268                                                         dirname, de->d_name);
 269                         } else {
 270                                 log_debug("Removed POSIX shared memory directory %s", de->d_name);
 271                                 if (ret == 0)
 272                                         ret = 1;
 273                         }
 274                 } else {
 275
 276                         if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 277                                 continue;
 278
 279                         if (!rm)
 280                                 return 1;
 281
 282                         if (unlinkat(dirfd(dir), de->d_name, 0) < 0) {
 283
 284                                 if (errno == ENOENT)
 285                                         continue;
 286
 287                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory segment %s: %m", de->d_name);
 288                         } else {
 289                                 log_debug("Removed POSIX shared memory segment %s", de->d_name);
 290                                 if (ret == 0)
 291                                         ret = 1;
 292                         }
 293                 }
 294         }
 295
 296         return ret;
 297
 298 fail:
 299         return log_warning_errno(errno, "Failed to read /dev/shm: %m");
 300 }
 301
 302 static int clean_posix_shm(uid_t uid, gid_t gid, bool rm) {
 303         _cleanup_closedir_ DIR *dir = NULL;
 304
 305         dir = opendir("/dev/shm");
 306         if (!dir) {
 307                 if (errno == ENOENT)
 308                         return 0;
 309
 310                 return log_warning_errno(errno, "Failed to open /dev/shm: %m");
 311         }
 312
 313         return clean_posix_shm_internal("/dev/shm", dir, uid, gid, rm);
 314 }
 315
 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
 375 int clean_ipc_internal(uid_t uid, gid_t gid, bool rm) {
 376         int ret = 0, r;
 377
 378         /* If 'rm' is true, clean all IPC objects owned by either the specified UID or the specified GID. Return the
 379          * last error encountered or == 0 if no matching IPC objects have been found or > 0 if matching IPC objects
 380          * have been found and have been removed.
 381          *
 382          * If 'rm' is false, just search for IPC objects owned by either the specified UID or the specified GID. In
 383          * this case we return < 0 on error, > 0 if we found a matching object, == 0 if we didn't.
 384          *
 385          * As special rule: if UID/GID is specified as root we'll silently not clean up things, and always claim that
 386          * there are IPC objects for it. */
 387
 388         if (uid == 0) {
 389                 if (!rm)
 390                         return 1;
 391
 392                 uid = UID_INVALID;
 393         }
 394         if (gid == 0) {
 395                 if (!rm)
 396                         return 1;
 397
 398                 gid = GID_INVALID;
 399         }
 400
 401         /* Anything to do? */
 402         if (!uid_is_valid(uid) && !gid_is_valid(gid))
 403                 return 0;
 404
 405         r = clean_sysvipc_shm(uid, gid, rm);
 406         if (r != 0) {
 407                 if (!rm)
 408                         return r;
 409                 if (ret == 0)
 410                         ret = r;
 411         }
 412
 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         r = clean_posix_mq(uid, gid, rm);
 438         if (r != 0) {
 439                 if (!rm)
 440                         return r;
 441                 if (ret == 0)
 442                         ret = r;
 443         }
 444
 445         return ret;
 446 }
 447
 448 int clean_ipc_by_uid(uid_t uid) {
 449         return clean_ipc_internal(uid, GID_INVALID, true);
 450 }
 451
 452 int clean_ipc_by_gid(gid_t gid) {
 453         return clean_ipc_internal(UID_INVALID, gid, true);
 454 }