src/shared/clean-ipc.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <dirent.h>
  21 #include <errno.h>
  22 #include <fcntl.h>
  23 #include <limits.h>
  24 #include <mqueue.h>
  25 #include <stdbool.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <sys/ipc.h>
  29 #include <sys/msg.h>
  30 #include <sys/sem.h>
  31 #include <sys/shm.h>
  32 #include <sys/stat.h>
  33 #include <unistd.h>
  34
  35 #include "clean-ipc.h"
  36 #include "dirent-util.h"
  37 #include "fd-util.h"
  38 #include "fileio.h"
  39 #include "formats-util.h"
  40 #include "log.h"
  41 #include "macro.h"
  42 #include "string-util.h"
  43 #include "strv.h"
  44 #include "user-util.h"
  45
  46 static bool match_uid_gid(uid_t subject_uid, gid_t subject_gid, uid_t delete_uid, gid_t delete_gid) {
  47
  48         if (uid_is_valid(delete_uid) && subject_uid == delete_uid)
  49                 return true;
  50
  51         if (gid_is_valid(delete_gid) && subject_gid == delete_gid)
  52                 return true;
  53
  54         return false;
  55 }
  56
  57 static int clean_sysvipc_shm(uid_t delete_uid, gid_t delete_gid) {
  58         _cleanup_fclose_ FILE *f = NULL;
  59         char line[LINE_MAX];
  60         bool first = true;
  61         int ret = 0;
  62
  63         f = fopen("/proc/sysvipc/shm", "re");
  64         if (!f) {
  65                 if (errno == ENOENT)
  66                         return 0;
  67
  68                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/shm: %m");
  69         }
  70
  71         FOREACH_LINE(line, f, goto fail) {
  72                 unsigned n_attached;
  73                 pid_t cpid, lpid;
  74                 uid_t uid, cuid;
  75                 gid_t gid, cgid;
  76                 int shmid;
  77
  78                 if (first) {
  79                         first = false;
  80                         continue;
  81                 }
  82
  83                 truncate_nl(line);
  84
  85                 if (sscanf(line, "%*i %i %*o %*u " PID_FMT " " PID_FMT " %u " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
  86                            &shmid, &cpid, &lpid, &n_attached, &uid, &gid, &cuid, &cgid) != 8)
  87                         continue;
  88
  89                 if (n_attached > 0)
  90                         continue;
  91
  92                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
  93                         continue;
  94
  95                 if (shmctl(shmid, IPC_RMID, NULL) < 0) {
  96
  97                         /* Ignore entries that are already deleted */
  98                         if (errno == EIDRM || errno == EINVAL)
  99                                 continue;
 100
 101                         ret = log_warning_errno(errno,
 102                                                 "Failed to remove SysV shared memory segment %i: %m",
 103                                                 shmid);
 104                 }
 105         }
 106
 107         return ret;
 108
 109 fail:
 110         return log_warning_errno(errno, "Failed to read /proc/sysvipc/shm: %m");
 111 }
 112
 113 static int clean_sysvipc_sem(uid_t delete_uid, gid_t delete_gid) {
 114         _cleanup_fclose_ FILE *f = NULL;
 115         char line[LINE_MAX];
 116         bool first = true;
 117         int ret = 0;
 118
 119         f = fopen("/proc/sysvipc/sem", "re");
 120         if (!f) {
 121                 if (errno == ENOENT)
 122                         return 0;
 123
 124                 return log_warning_errno(errno, "Failed to open /proc/sysvipc/sem: %m");
 125         }
 126
 127         FOREACH_LINE(line, f, goto fail) {
 128                 uid_t uid, cuid;
 129                 gid_t gid, cgid;
 130                 int semid;
 131
 132                 if (first) {
 133                         first = false;
 134                         continue;
 135                 }
 136
 137                 truncate_nl(line);
 138
 139                 if (sscanf(line, "%*i %i %*o %*u " UID_FMT " " GID_FMT " " UID_FMT " " GID_FMT,
 140                            &semid, &uid, &gid, &cuid, &cgid) != 5)
 141                         continue;
 142
 143                 if (!match_uid_gid(uid, gid, delete_uid, delete_gid))
 144                         continue;
 145
 146                 if (semctl(semid, 0, IPC_RMID) < 0) {
 147
 148                         /* Ignore entries that are already deleted */
 149                         if (errno == EIDRM || errno == EINVAL)
 150                                 continue;
 151
 152                         ret = log_warning_errno(errno,
 153                                                 "Failed to remove SysV semaphores object %i: %m",
 154                                                 semid);
 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) {
 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 (msgctl(msgid, IPC_RMID, NULL) < 0) {
 199
 200                         /* Ignore entries that are already deleted */
 201                         if (errno == EIDRM || errno == EINVAL)
 202                                 continue;
 203
 204                         ret = log_warning_errno(errno,
 205                                                 "Failed to remove SysV message queue %i: %m",
 206                                                 msgid);
 207                 }
 208         }
 209
 210         return ret;
 211
 212 fail:
 213         return log_warning_errno(errno, "Failed to read /proc/sysvipc/msg: %m");
 214 }
 215
 216 static int clean_posix_shm_internal(DIR *dir, uid_t uid, gid_t gid) {
 217         struct dirent *de;
 218         int ret = 0, r;
 219
 220         assert(dir);
 221
 222         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 223                 struct stat st;
 224
 225                 if (STR_IN_SET(de->d_name, "..", "."))
 226                         continue;
 227
 228                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 229                         if (errno == ENOENT)
 230                                 continue;
 231
 232                         ret = log_warning_errno(errno, "Failed to stat() POSIX shared memory segment %s: %m", de->d_name);
 233                         continue;
 234                 }
 235
 236                 if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 237                         continue;
 238
 239                 if (S_ISDIR(st.st_mode)) {
 240                         _cleanup_closedir_ DIR *kid;
 241
 242                         kid = xopendirat(dirfd(dir), de->d_name, O_NOFOLLOW|O_NOATIME);
 243                         if (!kid) {
 244                                 if (errno != ENOENT)
 245                                         ret = log_warning_errno(errno, "Failed to enter shared memory directory %s: %m", de->d_name);
 246                         } else {
 247                                 r = clean_posix_shm_internal(kid, uid, gid);
 248                                 if (r < 0)
 249                                         ret = r;
 250                         }
 251
 252                         if (unlinkat(dirfd(dir), de->d_name, AT_REMOVEDIR) < 0) {
 253
 254                                 if (errno == ENOENT)
 255                                         continue;
 256
 257                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory directory %s: %m", de->d_name);
 258                         }
 259                 } else {
 260
 261                         if (unlinkat(dirfd(dir), de->d_name, 0) < 0) {
 262
 263                                 if (errno == ENOENT)
 264                                         continue;
 265
 266                                 ret = log_warning_errno(errno, "Failed to remove POSIX shared memory segment %s: %m", de->d_name);
 267                         }
 268                 }
 269         }
 270
 271         return ret;
 272
 273 fail:
 274         return log_warning_errno(errno, "Failed to read /dev/shm: %m");
 275 }
 276
 277 static int clean_posix_shm(uid_t uid, gid_t gid) {
 278         _cleanup_closedir_ DIR *dir = NULL;
 279
 280         dir = opendir("/dev/shm");
 281         if (!dir) {
 282                 if (errno == ENOENT)
 283                         return 0;
 284
 285                 return log_warning_errno(errno, "Failed to open /dev/shm: %m");
 286         }
 287
 288         return clean_posix_shm_internal(dir, uid, gid);
 289 }
 290
 291 #if 0 /// UNNEEDED by elogind
 292 static int clean_posix_mq(uid_t uid, gid_t gid) {
 293         _cleanup_closedir_ DIR *dir = NULL;
 294         struct dirent *de;
 295         int ret = 0;
 296
 297         dir = opendir("/dev/mqueue");
 298         if (!dir) {
 299                 if (errno == ENOENT)
 300                         return 0;
 301
 302                 return log_warning_errno(errno, "Failed to open /dev/mqueue: %m");
 303         }
 304
 305         FOREACH_DIRENT_ALL(de, dir, goto fail) {
 306                 struct stat st;
 307                 char fn[1+strlen(de->d_name)+1];
 308
 309                 if (STR_IN_SET(de->d_name, "..", "."))
 310                         continue;
 311
 312                 if (fstatat(dirfd(dir), de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
 313                         if (errno == ENOENT)
 314                                 continue;
 315
 316                         ret = log_warning_errno(errno,
 317                                                 "Failed to stat() MQ segment %s: %m",
 318                                                 de->d_name);
 319                         continue;
 320                 }
 321
 322                 if (!match_uid_gid(st.st_uid, st.st_gid, uid, gid))
 323                         continue;
 324
 325                 fn[0] = '/';
 326                 strcpy(fn+1, de->d_name);
 327
 328                 if (mq_unlink(fn) < 0) {
 329                         if (errno == ENOENT)
 330                                 continue;
 331
 332                         ret = log_warning_errno(errno,
 333                                                 "Failed to unlink POSIX message queue %s: %m",
 334                                                 fn);
 335                 }
 336         }
 337
 338         return ret;
 339
 340 fail:
 341         return log_warning_errno(errno, "Failed to read /dev/mqueue: %m");
 342 }
 343 #endif // 0
 344
 345 int clean_ipc(uid_t uid, gid_t gid) {
 346         int ret = 0, r;
 347
 348         /* Anything to do? */
 349         if (!uid_is_valid(uid) && !gid_is_valid(gid))
 350                 return 0;
 351
 352         /* Refuse to clean IPC of the root user */
 353         if (uid == 0 && gid == 0)
 354                 return 0;
 355
 356         r = clean_sysvipc_shm(uid, gid);
 357         if (r < 0)
 358                 ret = r;
 359
 360         r = clean_sysvipc_sem(uid, gid);
 361         if (r < 0)
 362                 ret = r;
 363
 364         r = clean_sysvipc_msg(uid, gid);
 365         if (r < 0)
 366                 ret = r;
 367
 368         r = clean_posix_shm(uid, gid);
 369         if (r < 0)
 370                 ret = r;
 371
 372 #if 0 /// elogind does not use mq_open anywhere
 373         r = clean_posix_mq(uid, gid);
 374         if (r < 0)
 375                 ret = r;
 376 #endif // 0
 377
 378         return ret;
 379 }
 380
 381 int clean_ipc_by_uid(uid_t uid) {
 382         return clean_ipc(uid, GID_INVALID);
 383 }
 384
 385 int clean_ipc_by_gid(gid_t gid) {
 386         return clean_ipc(UID_INVALID, gid);
 387 }