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Systemd/src/mount-setup.c
Roberto Sassu 160481f68d systemd: mount the securityfs filesystem at early stage 
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The mount of the securityfs filesystem is now performed in the main systemd
executable as it is used by IMA to provide the interface for loading custom
policies. The unit file 'units/sys-kernel-security.mount' has been removed
because it is not longer necessary.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Acked-by: Gianluca Ramunno <ramunno@polito.it>
2012-03-22 00:20:48 +01:00

423 lines
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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 General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU 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 "log.h"
#include "macro.h"
#include "util.h"
#include "label.h"
#include "set.h"
#include "strv.h"
#ifndef TTY_GID
#define TTY_GID 5
#endif
typedef struct MountPoint {
const char *what;
const char *where;
const char *type;
const char *options;
unsigned long flags;
bool fatal;
} 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, true },
{ "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
{ "devtmpfs", "/dev", "devtmpfs", "mode=755", MS_NOSUID, true },
{ "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
{ "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV, true },
{ "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, false },
{ "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV, true },
{ "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
{ "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
};
/* 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 * const ignore_paths[] = {
"/sys/fs/selinux",
"/selinux",
"/proc/bus/usb"
};
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) {
unsigned i;
for (i = 0; i < ELEMENTSOF(ignore_paths); i++)
if (path_equal(path, ignore_paths[i]))
return true;
return false;
}
static int mount_one(const MountPoint *p, bool relabel) {
int r;
assert(p);
/* Relabel first, just in case */
if (relabel)
label_fix(p->where, true);
if ((r = path_is_mount_point(p->where, true)) < 0)
return r;
if (r > 0)
return 0;
/* The access mode here doesn't really matter too much, since
* the mounted file system will take precedence anyway. */
mkdir_p(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_error("Failed to mount %s: %s", p->where, strerror(errno));
return p->fatal ? -errno : 0;
}
/* Relabel again, since we now mounted something fresh here */
if (relabel)
label_fix(p->where, 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 = -ENOMEM;
log_error("Failed to allocate controller set.");
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) {
log_error("Failed to join options");
free(controller);
r = -ENOMEM;
goto finish;
}
} else {
options = controller;
controller = NULL;
}
where = strappend("/sys/fs/cgroup/", options);
if (!where) {
log_error("Failed to build path");
free(options);
r = -ENOMEM;
goto finish;
}
zero(p);
p.what = "cgroup";
p.where = where;
p.type = "cgroup";
p.options = options;
p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
p.fatal = false;
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) {
log_error("Failed to build path");
r = -ENOMEM;
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 symlink_and_label(const char *old_path, const char *new_path) {
int r;
assert(old_path);
assert(new_path);
if ((r = label_symlinkfile_set(new_path)) < 0)
return r;
if (symlink(old_path, new_path) < 0)
r = -errno;
label_file_clear();
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, true);
/* /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 symlinks[] =
"/proc/kcore\0" "/dev/core\0"
"/proc/self/fd\0" "/dev/fd\0"
"/proc/self/fd/0\0" "/dev/stdin\0"
"/proc/self/fd/1\0" "/dev/stdout\0"
"/proc/self/fd/2\0" "/dev/stderr\0";
static const char relabel[] =
"/run/initramfs/root-fsck\0"
"/run/initramfs/shutdown\0";
int r;
unsigned i;
const char *j, *k;
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);
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. */
NULSTR_FOREACH_PAIR(j, k, symlinks)
symlink_and_label(j, k);
/* Create a few directories we always want around */
label_mkdir("/run/systemd", 0755);
label_mkdir("/run/systemd/system", 0755);
return 0;
}
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