src/shared/clean-ipc.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   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         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/%s: %m",
 237                                                 dirname, de->d_name);
 238                         continue;
 239                 }
 240
 241                 if (S_ISDIR(st.st_mode)) {
 242                         _cleanup_closedir_ DIR *kid = NULL;
 243
 244                         kid = xopendirat(dirfd(dir), de->d_name, O_NOFOLLOW|O_NOATIME);
 245                         if (!kid) {
 246                                 if (errno != ENOENT)
 247                                         ret = log_warning_errno(errno, "Failed to enter shared memory directory %s/%s: %m",
 248                                                                 dirname, de->d_name);
 249                         } else {
 250                                 r = clean_posix_shm_internal(de->d_name, kid, uid, gid, rm);
 251                                 if (r < 0)
 252                                         ret = r;
 253                         }
 254
 255                         if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 256                                 continue;
 257
 258                         if (!rm)
 259                                 return 1;
 260
 261                         if (unlinkat(dirfd(dir), de->d_name, AT_REMOVEDIR) < 0) {
 262
 263                                 if (errno == ENOENT)
 264                                         continue;
 265
 266                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory directory %s/%s: %m",
 267                                                         dirname, 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("/dev/shm", 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         int ret = 0;
 318
 319         dir = opendir("/dev/mqueue");
 320         if (!dir) {
 321                 if (errno == ENOENT)
 322                         return 0;
 323
 324                 return log_warning_errno(errno, "Failed to open /dev/mqueue: %m");
 325         }
 326
 327         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 328                 struct stat st;
 329                 char fn[1+strlen(de->d_name)+1];
 330
 331                 if (dot_or_dot_dot(de->d_name))
 332                         continue;
 333
 334                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 335                         if (errno == ENOENT)
 336                                 continue;
 337
 338                         ret = log_warning_errno(errno,
 339                                                 "Failed to stat() MQ segment %s: %m",
 340                                                 de->d_name);
 341                         continue;
 342                 }
 343
 344                 if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 345                         continue;
 346
 347                 if (!rm)
 348                         return 1;
 349
 350                 fn[0] = '/';
 351                 strcpy(fn+1, de->d_name);
 352
 353                 if (mq_unlink(fn) < 0) {
 354                         if (errno == ENOENT)
 355                                 continue;
 356
 357                         ret = log_warning_errno(errno,
 358                                                 "Failed to unlink POSIX message queue %s: %m",
 359                                                 fn);
 360                 } else {
 361                         log_debug("Removed POSIX message queue %s", fn);
 362                         if (ret == 0)
 363                                 ret = 1;
 364                 }
 365         }
 366
 367         return ret;
 368
 369 fail:
 370         return log_warning_errno(errno, "Failed to read /dev/mqueue: %m");
 371 }
 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         r = clean_sysvipc_sem(uid, gid, rm);
 412         if (r != 0) {
 413                 if (!rm)
 414                         return r;
 415                 if (ret == 0)
 416                         ret = r;
 417         }
 418
 419         r = clean_sysvipc_msg(uid, gid, rm);
 420         if (r != 0) {
 421                 if (!rm)
 422                         return r;
 423                 if (ret == 0)
 424                         ret = r;
 425         }
 426
 427         r = clean_posix_shm(uid, gid, rm);
 428         if (r != 0) {
 429                 if (!rm)
 430                         return r;
 431                 if (ret == 0)
 432                         ret = r;
 433         }
 434
 435         r = clean_posix_mq(uid, gid, rm);
 436         if (r != 0) {
 437                 if (!rm)
 438                         return r;
 439                 if (ret == 0)
 440                         ret = r;
 441         }
 442
 443         return ret;
 444 }
 445
 446 int clean_ipc_by_uid(uid_t uid) {
 447         return clean_ipc_internal(uid, GID_INVALID, true);
 448 }
 449
 450 int clean_ipc_by_gid(gid_t gid) {
 451         return clean_ipc_internal(UID_INVALID, gid, true);
 452 }