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 <errno.h>
  23 #include <ftw.h>
  24 #include <stdlib.h>
  25 #include <sys/mount.h>
  26 #include <unistd.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 static int mount_points_setup(unsigned n, bool loaded_policy) {
 203         unsigned i;
 204         int r = 0;
 205
 206         for (i = 0; i < n; i ++) {
 207                 int j;
 208
 209                 j = mount_one(mount_table + i, loaded_policy);
 210                 if (j != 0 && r >= 0)
 211                         r = j;
 212         }
 213
 214         return r;
 215 }
 216
 217 int mount_setup_early(void) {
 218         assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table));
 219
 220         /* Do a minimal mount of /proc and friends to enable the most
 221          * basic stuff, such as SELinux */
 222         return mount_points_setup(N_EARLY_MOUNT, false);
 223 }
 224
 225 int mount_cgroup_controllers(char ***join_controllers) {
 226         _cleanup_set_free_free_ Set *controllers = NULL;
 227         int r;
 228
 229         if (!cg_is_legacy_wanted())
 230                 return 0;
 231
 232         /* Mount all available cgroup controllers that are built into the kernel. */
 233
 234         controllers = set_new(&string_hash_ops);
 235         if (!controllers)
 236                 return log_oom();
 237
 238         r = cg_kernel_controllers(controllers);
 239         if (r < 0)
 240                 return log_error_errno(r, "Failed to enumerate cgroup controllers: %m");
 241
 242         for (;;) {
 243                 _cleanup_free_ char *options = NULL, *controller = NULL, *where = NULL;
 244                 MountPoint p = {
 245                         .what = "cgroup",
 246                         .type = "cgroup",
 247                         .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV,
 248                         .mode = MNT_IN_CONTAINER,
 249                 };
 250                 char ***k = NULL;
 251
 252                 controller = set_steal_first(controllers);
 253                 if (!controller)
 254                         break;
 255
 256                 if (join_controllers)
 257                         for (k = join_controllers; *k; k++)
 258                                 if (strv_find(*k, controller))
 259                                         break;
 260
 261                 if (k && *k) {
 262                         char **i, **j;
 263
 264                         for (i = *k, j = *k; *i; i++) {
 265
 266                                 if (!streq(*i, controller)) {
 267                                         _cleanup_free_ char *t;
 268
 269                                         t = set_remove(controllers, *i);
 270                                         if (!t) {
 271                                                 free(*i);
 272                                                 continue;
 273                                         }
 274                                 }
 275
 276                                 *(j++) = *i;
 277                         }
 278
 279                         *j = NULL;
 280
 281                         options = strv_join(*k, ",");
 282                         if (!options)
 283                                 return log_oom();
 284                 } else {
 285                         options = controller;
 286                         controller = NULL;
 287                 }
 288
 289                 where = strappend("/sys/fs/cgroup/", options);
 290                 if (!where)
 291                         return log_oom();
 292
 293                 p.where = where;
 294                 p.options = options;
 295
 296                 r = mount_one(&p, true);
 297                 if (r < 0)
 298                         return r;
 299
 300                 if (r > 0 && k && *k) {
 301                         char **i;
 302
 303                         for (i = *k; *i; i++) {
 304                                 _cleanup_free_ char *t = NULL;
 305
 306                                 t = strappend("/sys/fs/cgroup/", *i);
 307                                 if (!t)
 308                                         return log_oom();
 309
 310                                 r = symlink(options, t);
 311                                 if (r >= 0) {
 312 #ifdef SMACK_RUN_LABEL
 313                                         _cleanup_free_ char *src;
 314                                         src = strappend("/sys/fs/cgroup/", options);
 315                                         if (!src)
 316                                                 return log_oom();
 317                                         r = mac_smack_copy(t, src);
 318                                         if (r < 0 && r != -EOPNOTSUPP)
 319                                                 return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", src, t);
 320 #endif
 321                                 } else if (errno != EEXIST)
 322                                         return log_error_errno(errno, "Failed to create symlink %s: %m", t);
 323                         }
 324                 }
 325         }
 326
 327         /* Now that we mounted everything, let's make the tmpfs the
 328          * cgroup file systems are mounted into read-only. */
 329         (void) mount("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755");
 330
 331         return 0;
 332 }
 333
 334 #if defined(HAVE_SELINUX) || defined(HAVE_SMACK)
 335 static int nftw_cb(
 336                 const char *fpath,
 337                 const struct stat *sb,
 338                 int tflag,
 339                 struct FTW *ftwbuf) {
 340
 341         /* No need to label /dev twice in a row... */
 342         if (_unlikely_(ftwbuf->level == 0))
 343                 return FTW_CONTINUE;
 344
 345         label_fix(fpath, false, false);
 346
 347         /* /run/initramfs is static data and big, no need to
 348          * dynamically relabel its contents at boot... */
 349         if (_unlikely_(ftwbuf->level == 1 &&
 350                       tflag == FTW_D &&
 351                       streq(fpath, "/run/initramfs")))
 352                 return FTW_SKIP_SUBTREE;
 353
 354         return FTW_CONTINUE;
 355 };
 356 #endif
 357
 358 int mount_setup(bool loaded_policy) {
 359         int r = 0;
 360
 361         r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy);
 362
 363         if (r < 0)
 364                 return r;
 365
 366 #if defined(HAVE_SELINUX) || defined(HAVE_SMACK)
 367         /* Nodes in devtmpfs and /run need to be manually updated for
 368          * the appropriate labels, after mounting. The other virtual
 369          * API file systems like /sys and /proc do not need that, they
 370          * use the same label for all their files. */
 371         if (loaded_policy) {
 372                 usec_t before_relabel, after_relabel;
 373                 char timespan[FORMAT_TIMESPAN_MAX];
 374
 375                 before_relabel = now(CLOCK_MONOTONIC);
 376
 377                 nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
 378                 nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
 379
 380                 after_relabel = now(CLOCK_MONOTONIC);
 381
 382                 log_info("Relabelled /dev and /run in %s.",
 383                          format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel, 0));
 384         }
 385 #endif
 386
 387         /* Create a few default symlinks, which are normally created
 388          * by udevd, but some scripts might need them before we start
 389          * udevd. */
 390         dev_setup(NULL, UID_INVALID, GID_INVALID);
 391
 392         /* Mark the root directory as shared in regards to mount
 393          * propagation. The kernel defaults to "private", but we think
 394          * it makes more sense to have a default of "shared" so that
 395          * nspawn and the container tools work out of the box. If
 396          * specific setups need other settings they can reset the
 397          * propagation mode to private if needed. */
 398         if (detect_container() <= 0)
 399                 if (mount(NULL, "/", NULL, MS_REC|MS_SHARED, NULL) < 0)
 400                         log_warning_errno(errno, "Failed to set up the root directory for shared mount propagation: %m");
 401
 402         /* Create a few directories we always want around, Note that
 403          * sd_booted() checks for /run/systemd/system, so this mkdir
 404          * really needs to stay for good, otherwise software that
 405          * copied sd-daemon.c into their sources will misdetect
 406          * systemd. */
 407         mkdir_label("/run/systemd", 0755);
 408         mkdir_label("/run/systemd/system", 0755);
 409         mkdir_label("/run/systemd/inaccessible", 0000);
 410
 411         return 0;
 412 }