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-rw-r--r--src/core/mount-setup.c441
1 files changed, 441 insertions, 0 deletions
diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
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+++ b/src/core/mount-setup.c
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+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/mount.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+#include <assert.h>
+#include <unistd.h>
+#include <ftw.h>
+
+#include "mount-setup.h"
+#include "dev-setup.h"
+#include "log.h"
+#include "macro.h"
+#include "util.h"
+#include "label.h"
+#include "set.h"
+#include "strv.h"
+#include "mkdir.h"
+#include "path-util.h"
+#include "missing.h"
+#include "virt.h"
+
+#ifndef TTY_GID
+#define TTY_GID 5
+#endif
+
+typedef enum MountMode {
+ MNT_NONE = 0,
+ MNT_FATAL = 1 << 0,
+ MNT_IN_CONTAINER = 1 << 1,
+} MountMode;
+
+typedef struct MountPoint {
+ const char *what;
+ const char *where;
+ const char *type;
+ const char *options;
+ unsigned long flags;
+ bool (*condition_fn)(void);
+ MountMode mode;
+} MountPoint;
+
+/* The first three entries we might need before SELinux is up. The
+ * fourth (securityfs) is needed by IMA to load a custom policy. The
+ * other ones we can delay until SELinux and IMA are loaded. */
+#define N_EARLY_MOUNT 4
+
+static const MountPoint mount_table[] = {
+ { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ NULL, MNT_FATAL|MNT_IN_CONTAINER },
+ { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ NULL, MNT_FATAL|MNT_IN_CONTAINER },
+ { "devtmpfs", "/dev", "devtmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME,
+ NULL, MNT_FATAL|MNT_IN_CONTAINER },
+ { "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ NULL, MNT_NONE },
+ { "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ is_efiboot, MNT_NONE },
+ { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
+ NULL, MNT_FATAL|MNT_IN_CONTAINER },
+ { "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC,
+ NULL, MNT_IN_CONTAINER },
+ { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
+ NULL, MNT_FATAL|MNT_IN_CONTAINER },
+ { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME,
+ NULL, MNT_IN_CONTAINER },
+ { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ NULL, MNT_IN_CONTAINER },
+};
+
+/* These are API file systems that might be mounted by other software,
+ * we just list them here so that we know that we should ignore them */
+
+static const char ignore_paths[] =
+ /* SELinux file systems */
+ "/sys/fs/selinux\0"
+ "/selinux\0"
+ /* Legacy cgroup mount points */
+ "/dev/cgroup\0"
+ "/cgroup\0"
+ /* Legacy kernel file system */
+ "/proc/bus/usb\0"
+ /* Container bind mounts */
+ "/proc/sys\0"
+ "/dev/console\0"
+ "/proc/kmsg\0";
+
+bool mount_point_is_api(const char *path) {
+ unsigned i;
+
+ /* Checks if this mount point is considered "API", and hence
+ * should be ignored */
+
+ for (i = 0; i < ELEMENTSOF(mount_table); i ++)
+ if (path_equal(path, mount_table[i].where))
+ return true;
+
+ return path_startswith(path, "/sys/fs/cgroup/");
+}
+
+bool mount_point_ignore(const char *path) {
+ const char *i;
+
+ NULSTR_FOREACH(i, ignore_paths)
+ if (path_equal(path, i))
+ return true;
+
+ return false;
+}
+
+static int mount_one(const MountPoint *p, bool relabel) {
+ int r;
+
+ assert(p);
+
+ if (p->condition_fn && !p->condition_fn())
+ return 0;
+
+ /* Relabel first, just in case */
+ if (relabel)
+ label_fix(p->where, true, true);
+
+ r = path_is_mount_point(p->where, true);
+ if (r < 0)
+ return r;
+
+ if (r > 0)
+ return 0;
+
+ /* Skip securityfs in a container */
+ if (!(p->mode & MNT_IN_CONTAINER) && detect_container(NULL) > 0)
+ return 0;
+
+ /* The access mode here doesn't really matter too much, since
+ * the mounted file system will take precedence anyway. */
+ mkdir_p_label(p->where, 0755);
+
+ log_debug("Mounting %s to %s of type %s with options %s.",
+ p->what,
+ p->where,
+ p->type,
+ strna(p->options));
+
+ if (mount(p->what,
+ p->where,
+ p->type,
+ p->flags,
+ p->options) < 0) {
+ log_full((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, "Failed to mount %s: %s", p->where, strerror(errno));
+ return (p->mode & MNT_FATAL) ? -errno : 0;
+ }
+
+ /* Relabel again, since we now mounted something fresh here */
+ if (relabel)
+ label_fix(p->where, false, false);
+
+ return 1;
+}
+
+int mount_setup_early(void) {
+ unsigned i;
+ int r = 0;
+
+ assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table));
+
+ /* Do a minimal mount of /proc and friends to enable the most
+ * basic stuff, such as SELinux */
+ for (i = 0; i < N_EARLY_MOUNT; i ++) {
+ int j;
+
+ j = mount_one(mount_table + i, false);
+ if (r == 0)
+ r = j;
+ }
+
+ return r;
+}
+
+int mount_cgroup_controllers(char ***join_controllers) {
+ int r;
+ FILE *f;
+ char buf[LINE_MAX];
+ Set *controllers;
+
+ /* Mount all available cgroup controllers that are built into the kernel. */
+
+ f = fopen("/proc/cgroups", "re");
+ if (!f) {
+ log_error("Failed to enumerate cgroup controllers: %m");
+ return 0;
+ }
+
+ controllers = set_new(string_hash_func, string_compare_func);
+ if (!controllers) {
+ r = log_oom();
+ goto finish;
+ }
+
+ /* Ignore the header line */
+ (void) fgets(buf, sizeof(buf), f);
+
+ for (;;) {
+ char *controller;
+ int enabled = 0;
+
+ if (fscanf(f, "%ms %*i %*i %i", &controller, &enabled) != 2) {
+
+ if (feof(f))
+ break;
+
+ log_error("Failed to parse /proc/cgroups.");
+ r = -EIO;
+ goto finish;
+ }
+
+ if (!enabled) {
+ free(controller);
+ continue;
+ }
+
+ r = set_put(controllers, controller);
+ if (r < 0) {
+ log_error("Failed to add controller to set.");
+ free(controller);
+ goto finish;
+ }
+ }
+
+ for (;;) {
+ MountPoint p;
+ char *controller, *where, *options;
+ char ***k = NULL;
+
+ controller = set_steal_first(controllers);
+ if (!controller)
+ break;
+
+ if (join_controllers)
+ for (k = join_controllers; *k; k++)
+ if (strv_find(*k, controller))
+ break;
+
+ if (k && *k) {
+ char **i, **j;
+
+ for (i = *k, j = *k; *i; i++) {
+
+ if (!streq(*i, controller)) {
+ char *t;
+
+ t = set_remove(controllers, *i);
+ if (!t) {
+ free(*i);
+ continue;
+ }
+ free(t);
+ }
+
+ *(j++) = *i;
+ }
+
+ *j = NULL;
+
+ options = strv_join(*k, ",");
+ if (!options) {
+ free(controller);
+ r = log_oom();
+ goto finish;
+ }
+
+ } else {
+ options = controller;
+ controller = NULL;
+ }
+
+ where = strappend("/sys/fs/cgroup/", options);
+ if (!where) {
+ free(options);
+ r = log_oom();
+ goto finish;
+ }
+
+ zero(p);
+ p.what = "cgroup";
+ p.where = where;
+ p.type = "cgroup";
+ p.options = options;
+ p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
+
+ r = mount_one(&p, true);
+ free(controller);
+ free(where);
+
+ if (r < 0) {
+ free(options);
+ goto finish;
+ }
+
+ if (r > 0 && k && *k) {
+ char **i;
+
+ for (i = *k; *i; i++) {
+ char *t;
+
+ t = strappend("/sys/fs/cgroup/", *i);
+ if (!t) {
+ r = log_oom();
+ free(options);
+ goto finish;
+ }
+
+ r = symlink(options, t);
+ free(t);
+
+ if (r < 0 && errno != EEXIST) {
+ log_error("Failed to create symlink: %m");
+ r = -errno;
+ free(options);
+ goto finish;
+ }
+ }
+ }
+
+ free(options);
+ }
+
+ r = 0;
+
+finish:
+ set_free_free(controllers);
+
+ fclose(f);
+
+ return r;
+}
+
+static int nftw_cb(
+ const char *fpath,
+ const struct stat *sb,
+ int tflag,
+ struct FTW *ftwbuf) {
+
+ /* No need to label /dev twice in a row... */
+ if (_unlikely_(ftwbuf->level == 0))
+ return FTW_CONTINUE;
+
+ label_fix(fpath, false, false);
+
+ /* /run/initramfs is static data and big, no need to
+ * dynamically relabel its contents at boot... */
+ if (_unlikely_(ftwbuf->level == 1 &&
+ tflag == FTW_D &&
+ streq(fpath, "/run/initramfs")))
+ return FTW_SKIP_SUBTREE;
+
+ return FTW_CONTINUE;
+};
+
+int mount_setup(bool loaded_policy) {
+
+ static const char relabel[] =
+ "/run/initramfs/root-fsck\0"
+ "/run/initramfs/shutdown\0";
+
+ int r;
+ unsigned i;
+ const char *j;
+
+ for (i = 0; i < ELEMENTSOF(mount_table); i ++) {
+ r = mount_one(mount_table + i, true);
+
+ if (r < 0)
+ return r;
+ }
+
+ /* Nodes in devtmpfs and /run need to be manually updated for
+ * the appropriate labels, after mounting. The other virtual
+ * API file systems like /sys and /proc do not need that, they
+ * use the same label for all their files. */
+ if (loaded_policy) {
+ usec_t before_relabel, after_relabel;
+ char timespan[FORMAT_TIMESPAN_MAX];
+
+ before_relabel = now(CLOCK_MONOTONIC);
+
+ nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
+ nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
+
+ /* Explicitly relabel these */
+ NULSTR_FOREACH(j, relabel)
+ label_fix(j, true, false);
+
+ after_relabel = now(CLOCK_MONOTONIC);
+
+ log_info("Relabelled /dev and /run in %s.",
+ format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel));
+ }
+
+ /* Create a few default symlinks, which are normally created
+ * by udevd, but some scripts might need them before we start
+ * udevd. */
+ dev_setup(NULL);
+
+ /* Mark the root directory as shared in regards to mount
+ * propagation. The kernel defaults to "private", but we think
+ * it makes more sense to have a default of "shared" so that
+ * nspawn and the container tools work out of the box. If
+ * specific setups need other settings they can reset the
+ * propagation mode to private if needed. */
+ if (detect_container(NULL) <= 0)
+ if (mount(NULL, "/", NULL, MS_REC|MS_SHARED, NULL) < 0)
+ log_warning("Failed to set up the root directory for shared mount propagation: %m");
+
+ /* Create a few directories we always want around */
+ mkdir_label("/run/systemd", 0755);
+ mkdir_label("/run/systemd/system", 0755);
+
+ return 0;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-14 12:18:43 +0000