ffbd2c4d45
SMACK is the Simple Mandatory Access Control Kernel, a minimal approach to Access Control implemented as a kernel LSM. The kernel exposes the smackfs filesystem API through which access rules can be loaded. At boot time, we want to load the access rules as early as possible to ensure all early boot steps are checked by Smack. This patch mounts smackfs at the new location at /sys/fs/smackfs for kernels 3.8 and above. The /smack mountpoint is not supported. After mounting smackfs, rules are loaded from the usual location. For more information about Smack see: http://www.kernel.org/doc/Documentation/security/Smack.txt
449 lines
14 KiB
C
449 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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#include "efivars.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 5
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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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{ "smackfs", "/sys/fs/smackfs", "smackfs", "smackfsdef=*", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME,
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NULL, 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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{ "pstore", "/sys/fs/pstore", "pstore", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
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NULL, MNT_NONE },
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#ifdef ENABLE_EFI
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{ "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
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is_efi_boot, MNT_NONE },
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#endif
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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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