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