src/core/mount-setup.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/mount.h>
  23 #include <errno.h>
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <ftw.h>
  27
  28 #include "alloc-util.h"
  29 #include "bus-util.h"
  30 #include "cgroup-util.h"
  31 #include "dev-setup.h"
  32 #include "efivars.h"
  33 #include "label.h"
  34 #include "log.h"
  35 #include "macro.h"
  36 #include "missing.h"
  37 #include "mkdir.h"
  38 #include "mount-setup.h"
  39 #include "mount-util.h"
  40 #include "path-util.h"
  41 #include "set.h"
  42 #include "smack-util.h"
  43 #include "strv.h"
  44 #include "user-util.h"
  45 #include "util.h"
  46 #include "virt.h"
  47
  48 typedef enum MountMode {
  49         MNT_NONE  =        0,
  50         MNT_FATAL =        1 <<  0,
  51         MNT_IN_CONTAINER = 1 <<  1,
  52 } MountMode;
  53
  54 typedef struct MountPoint {
  55         const char *what;
  56         const char *where;
  57         const char *type;
  58         const char *options;
  59         unsigned long flags;
  60         bool (*condition_fn)(void);
  61         MountMode mode;
  62 } MountPoint;
  63
  64 /* The first three entries we might need before SELinux is up. The
  65  * fourth (securityfs) is needed by IMA to load a custom policy. The
  66  * other ones we can delay until SELinux and IMA are loaded. When
  67  * SMACK is enabled we need smackfs, too, so it's a fifth one. */
  68 #ifdef HAVE_SMACK
  69 #define N_EARLY_MOUNT 5
  70 #else
  71 #define N_EARLY_MOUNT 4
  72 #endif
  73
  74 static const MountPoint mount_table[] = {
  75         { "sysfs",       "/sys",                      "sysfs",      NULL,                      MS_NOSUID|MS_NOEXEC|MS_NODEV,
  76           NULL,          MNT_FATAL|MNT_IN_CONTAINER },
  77         { "proc",        "/proc",                     "proc",       NULL,                      MS_NOSUID|MS_NOEXEC|MS_NODEV,
  78           NULL,          MNT_FATAL|MNT_IN_CONTAINER },
  79         { "devtmpfs",    "/dev",                      "devtmpfs",   "mode=755",                MS_NOSUID|MS_STRICTATIME,
  80           NULL,          MNT_FATAL|MNT_IN_CONTAINER },
  81         { "securityfs",  "/sys/kernel/security",      "securityfs", NULL,                      MS_NOSUID|MS_NOEXEC|MS_NODEV,
  82           NULL,          MNT_NONE                   },
  83 #ifdef HAVE_SMACK
  84         { "smackfs",     "/sys/fs/smackfs",           "smackfs",    "smackfsdef=*",            MS_NOSUID|MS_NOEXEC|MS_NODEV,
  85           mac_smack_use, MNT_FATAL                  },
  86         { "tmpfs",       "/dev/shm",                  "tmpfs",      "mode=1777,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
  87           mac_smack_use, MNT_FATAL                  },
  88 #endif
  89         { "tmpfs",       "/dev/shm",                  "tmpfs",      "mode=1777",               MS_NOSUID|MS_NODEV|MS_STRICTATIME,
  90           NULL,          MNT_FATAL|MNT_IN_CONTAINER },
  91         { "devpts",      "/dev/pts",                  "devpts",     "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC,
  92           NULL,          MNT_IN_CONTAINER           },
  93 #ifdef HAVE_SMACK
  94         { "tmpfs",       "/run",                      "tmpfs",      "mode=755,smackfsroot=*",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,
  95           mac_smack_use, MNT_FATAL                  },
  96 #endif
  97         { "tmpfs",       "/run",                      "tmpfs",      "mode=755",                MS_NOSUID|MS_NODEV|MS_STRICTATIME,
  98           NULL,          MNT_FATAL|MNT_IN_CONTAINER },
  99         { "cgroup",      "/sys/fs/cgroup",            "cgroup",     "__DEVEL__sane_behavior",  MS_NOSUID|MS_NOEXEC|MS_NODEV,
 100           cg_is_unified_wanted, MNT_FATAL|MNT_IN_CONTAINER },
 101         { "tmpfs",       "/sys/fs/cgroup",            "tmpfs",      "mode=755",                MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME,
 102           cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER },
 103         { "cgroup",      "/sys/fs/cgroup/systemd",    "cgroup",     "none,name=systemd,xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV,
 104           cg_is_legacy_wanted, MNT_IN_CONTAINER           },
 105         { "cgroup",      "/sys/fs/cgroup/systemd",    "cgroup",     "none,name=systemd",       MS_NOSUID|MS_NOEXEC|MS_NODEV,
 106           cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER },
 107         { "pstore",      "/sys/fs/pstore",            "pstore",     NULL,                      MS_NOSUID|MS_NOEXEC|MS_NODEV,
 108           NULL,          MNT_NONE                   },
 109 #ifdef ENABLE_EFI
 110         { "efivarfs",    "/sys/firmware/efi/efivars", "efivarfs",   NULL,                      MS_NOSUID|MS_NOEXEC|MS_NODEV,
 111           is_efi_boot,   MNT_NONE                   },
 112 #endif
 113         { "kdbusfs",    "/sys/fs/kdbus",             "kdbusfs",    NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
 114           is_kdbus_wanted,       MNT_IN_CONTAINER },
 115 };
 116
 117 /* These are API file systems that might be mounted by other software,
 118  * we just list them here so that we know that we should ignore them */
 119
 120 static const char ignore_paths[] =
 121         /* SELinux file systems */
 122         "/sys/fs/selinux\0"
 123         /* Container bind mounts */
 124         "/proc/sys\0"
 125         "/dev/console\0"
 126         "/proc/kmsg\0";
 127
 128 bool mount_point_is_api(const char *path) {
 129         unsigned i;
 130
 131         /* Checks if this mount point is considered "API", and hence
 132          * should be ignored */
 133
 134         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
 135                 if (path_equal(path, mount_table[i].where))
 136                         return true;
 137
 138         return path_startswith(path, "/sys/fs/cgroup/");
 139 }
 140
 141 bool mount_point_ignore(const char *path) {
 142         const char *i;
 143
 144         NULSTR_FOREACH(i, ignore_paths)
 145                 if (path_equal(path, i))
 146                         return true;
 147
 148         return false;
 149 }
 150
 151 static int mount_one(const MountPoint *p, bool relabel) {
 152         int r;
 153
 154         assert(p);
 155
 156         if (p->condition_fn && !p->condition_fn())
 157                 return 0;
 158
 159         /* Relabel first, just in case */
 160         if (relabel)
 161                 label_fix(p->where, true, true);
 162
 163         r = path_is_mount_point(p->where, AT_SYMLINK_FOLLOW);
 164         if (r < 0 && r != -ENOENT)
 165                 return r;
 166         if (r > 0)
 167                 return 0;
 168
 169         /* Skip securityfs in a container */
 170         if (!(p->mode & MNT_IN_CONTAINER) && detect_container() > 0)
 171                 return 0;
 172
 173         /* The access mode here doesn't really matter too much, since
 174          * the mounted file system will take precedence anyway. */
 175         if (relabel)
 176                 mkdir_p_label(p->where, 0755);
 177         else
 178                 mkdir_p(p->where, 0755);
 179
 180         log_debug("Mounting %s to %s of type %s with options %s.",
 181                   p->what,
 182                   p->where,
 183                   p->type,
 184                   strna(p->options));
 185
 186         if (mount(p->what,
 187                   p->where,
 188                   p->type,
 189                   p->flags,
 190                   p->options) < 0) {
 191                 log_full((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, "Failed to mount %s at %s: %m", p->type, p->where);
 192                 return (p->mode & MNT_FATAL) ? -errno : 0;
 193         }
 194
 195         /* Relabel again, since we now mounted something fresh here */
 196         if (relabel)
 197                 label_fix(p->where, false, false);
 198
 199         return 1;
 200 }
 201
 202 int mount_setup_early(void) {
 203         unsigned i;
 204         int r = 0;
 205
 206         assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table));
 207
 208         /* Do a minimal mount of /proc and friends to enable the most
 209          * basic stuff, such as SELinux */
 210         for (i = 0; i < N_EARLY_MOUNT; i ++)  {
 211                 int j;
 212
 213                 j = mount_one(mount_table + i, false);
 214                 if (j != 0 && r >= 0)
 215                         r = j;
 216         }
 217
 218         return r;
 219 }
 220
 221 int mount_cgroup_controllers(char ***join_controllers) {
 222         _cleanup_set_free_free_ Set *controllers = NULL;
 223         int r;
 224
 225         if (!cg_is_legacy_wanted())
 226                 return 0;
 227
 228         /* Mount all available cgroup controllers that are built into the kernel. */
 229
 230         controllers = set_new(&string_hash_ops);
 231         if (!controllers)
 232                 return log_oom();
 233
 234         r = cg_kernel_controllers(controllers);
 235         if (r < 0)
 236                 return log_error_errno(r, "Failed to enumerate cgroup controllers: %m");
 237
 238         for (;;) {
 239                 _cleanup_free_ char *options = NULL, *controller = NULL, *where = NULL;
 240                 MountPoint p = {
 241                         .what = "cgroup",
 242                         .type = "cgroup",
 243                         .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV,
 244                         .mode = MNT_IN_CONTAINER,
 245                 };
 246                 char ***k = NULL;
 247
 248                 controller = set_steal_first(controllers);
 249                 if (!controller)
 250                         break;
 251
 252                 if (join_controllers)
 253                         for (k = join_controllers; *k; k++)
 254                                 if (strv_find(*k, controller))
 255                                         break;
 256
 257                 if (k && *k) {
 258                         char **i, **j;
 259
 260                         for (i = *k, j = *k; *i; i++) {
 261
 262                                 if (!streq(*i, controller)) {
 263                                         _cleanup_free_ char *t;
 264
 265                                         t = set_remove(controllers, *i);
 266                                         if (!t) {
 267                                                 free(*i);
 268                                                 continue;
 269                                         }
 270                                 }
 271
 272                                 *(j++) = *i;
 273                         }
 274
 275                         *j = NULL;
 276
 277                         options = strv_join(*k, ",");
 278                         if (!options)
 279                                 return log_oom();
 280                 } else {
 281                         options = controller;
 282                         controller = NULL;
 283                 }
 284
 285                 where = strappend("/sys/fs/cgroup/", options);
 286                 if (!where)
 287                         return log_oom();
 288
 289                 p.where = where;
 290                 p.options = options;
 291
 292                 r = mount_one(&p, true);
 293                 if (r < 0)
 294                         return r;
 295
 296                 if (r > 0 && k && *k) {
 297                         char **i;
 298
 299                         for (i = *k; *i; i++) {
 300                                 _cleanup_free_ char *t = NULL;
 301
 302                                 t = strappend("/sys/fs/cgroup/", *i);
 303                                 if (!t)
 304                                         return log_oom();
 305
 306                                 r = symlink(options, t);
 307                                 if (r < 0 && errno != EEXIST)
 308                                         return log_error_errno(errno, "Failed to create symlink %s: %m", t);
 309 #ifdef SMACK_RUN_LABEL
 310                                 r = mac_smack_copy(t, options);
 311                                 if (r < 0 && r != -EOPNOTSUPP)
 312                                         return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", options, t);
 313 #endif
 314                         }
 315                 }
 316         }
 317
 318         /* Now that we mounted everything, let's make the tmpfs the
 319          * cgroup file systems are mounted into read-only. */
 320         (void) mount("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755");
 321
 322         return 0;
 323 }
 324
 325 #if defined(HAVE_SELINUX) || defined(HAVE_SMACK)
 326 static int nftw_cb(
 327                 const char *fpath,
 328                 const struct stat *sb,
 329                 int tflag,
 330                 struct FTW *ftwbuf) {
 331
 332         /* No need to label /dev twice in a row... */
 333         if (_unlikely_(ftwbuf->level == 0))
 334                 return FTW_CONTINUE;
 335
 336         label_fix(fpath, false, false);
 337
 338         /* /run/initramfs is static data and big, no need to
 339          * dynamically relabel its contents at boot... */
 340         if (_unlikely_(ftwbuf->level == 1 &&
 341                       tflag == FTW_D &&
 342                       streq(fpath, "/run/initramfs")))
 343                 return FTW_SKIP_SUBTREE;
 344
 345         return FTW_CONTINUE;
 346 };
 347 #endif
 348
 349 int mount_setup(bool loaded_policy) {
 350         unsigned i;
 351         int r = 0;
 352
 353         for (i = 0; i < ELEMENTSOF(mount_table); i ++) {
 354                 int j;
 355
 356                 j = mount_one(mount_table + i, loaded_policy);
 357                 if (j != 0 && r >= 0)
 358                         r = j;
 359         }
 360
 361         if (r < 0)
 362                 return r;
 363
 364 #if defined(HAVE_SELINUX) || defined(HAVE_SMACK)
 365         /* Nodes in devtmpfs and /run need to be manually updated for
 366          * the appropriate labels, after mounting. The other virtual
 367          * API file systems like /sys and /proc do not need that, they
 368          * use the same label for all their files. */
 369         if (loaded_policy) {
 370                 usec_t before_relabel, after_relabel;
 371                 char timespan[FORMAT_TIMESPAN_MAX];
 372
 373                 before_relabel = now(CLOCK_MONOTONIC);
 374
 375                 nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
 376                 nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
 377
 378                 after_relabel = now(CLOCK_MONOTONIC);
 379
 380                 log_info("Relabelled /dev and /run in %s.",
 381                          format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel, 0));
 382         }
 383 #endif
 384
 385         /* Create a few default symlinks, which are normally created
 386          * by udevd, but some scripts might need them before we start
 387          * udevd. */
 388         dev_setup(NULL, UID_INVALID, GID_INVALID);
 389
 390         /* Mark the root directory as shared in regards to mount
 391          * propagation. The kernel defaults to "private", but we think
 392          * it makes more sense to have a default of "shared" so that
 393          * nspawn and the container tools work out of the box. If
 394          * specific setups need other settings they can reset the
 395          * propagation mode to private if needed. */
 396         if (detect_container() <= 0)
 397                 if (mount(NULL, "/", NULL, MS_REC|MS_SHARED, NULL) < 0)
 398                         log_warning_errno(errno, "Failed to set up the root directory for shared mount propagation: %m");
 399
 400         /* Create a few directories we always want around, Note that
 401          * sd_booted() checks for /run/systemd/system, so this mkdir
 402          * really needs to stay for good, otherwise software that
 403          * copied sd-daemon.c into their sources will misdetect
 404          * systemd. */
 405         mkdir_label("/run/systemd", 0755);
 406         mkdir_label("/run/systemd/system", 0755);
 407         mkdir_label("/run/systemd/inaccessible", 0000);
 408
 409         return 0;
 410 }