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systemd/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;
}
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