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Systemd/src/core/namespace.c
Djalal Harouni 1d54cd5d25 core:namespace: count and free failed paths inside chase_all_symlinks() (#4619) 
This certainly fixes a bug that was introduced by PR
https://github.com/systemd/systemd/pull/4594 that intended to fix
https://github.com/systemd/systemd/issues/4567.

The fix was not complete. This patch makes sure that we count and free
all paths that fail inside chase_all_symlinks().

Fixes https://github.com/systemd/systemd/issues/4567
2016-11-10 12:11:37 -05:00

1086 lines
35 KiB
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/***
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 <errno.h>
#include <sched.h>
#include <stdio.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/fs.h>
#include "alloc-util.h"
#include "dev-setup.h"
#include "fd-util.h"
#include "fs-util.h"
#include "loopback-setup.h"
#include "missing.h"
#include "mkdir.h"
#include "mount-util.h"
#include "namespace.h"
#include "path-util.h"
#include "selinux-util.h"
#include "socket-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "umask-util.h"
#include "user-util.h"
#include "util.h"
#define DEV_MOUNT_OPTIONS (MS_NOSUID|MS_STRICTATIME|MS_NOEXEC)
typedef enum MountMode {
/* This is ordered by priority! */
INACCESSIBLE,
READONLY,
PRIVATE_TMP,
PRIVATE_VAR_TMP,
PRIVATE_DEV,
READWRITE,
} MountMode;
typedef struct BindMount {
char *path;
MountMode mode;
bool ignore; /* Ignore if path does not exist */
} BindMount;
typedef struct TargetMount {
const char *path;
MountMode mode;
bool ignore; /* Ignore if path does not exist */
} TargetMount;
/*
* The following Protect tables are to protect paths and mark some of them
* READONLY, in case a path is covered by an option from another table, then
* it is marked READWRITE in the current one, and the more restrictive mode is
* applied from that other table. This way all options can be combined in a
* safe and comprehensible way for users.
*/
/* ProtectKernelTunables= option and the related filesystem APIs */
static const TargetMount protect_kernel_tunables_table[] = {
{ "/proc/sys", READONLY, false },
{ "/proc/sysrq-trigger", READONLY, true },
{ "/proc/latency_stats", READONLY, true },
{ "/proc/mtrr", READONLY, true },
{ "/proc/apm", READONLY, true },
{ "/proc/acpi", READONLY, true },
{ "/proc/timer_stats", READONLY, true },
{ "/proc/asound", READONLY, true },
{ "/proc/bus", READONLY, true },
{ "/proc/fs", READONLY, true },
{ "/proc/irq", READONLY, true },
{ "/sys", READONLY, false },
{ "/sys/kernel/debug", READONLY, true },
{ "/sys/kernel/tracing", READONLY, true },
{ "/sys/fs/cgroup", READWRITE, false }, /* READONLY is set by ProtectControlGroups= option */
};
/* ProtectKernelModules= option */
static const TargetMount protect_kernel_modules_table[] = {
#ifdef HAVE_SPLIT_USR
{ "/lib/modules", INACCESSIBLE, true },
#endif
{ "/usr/lib/modules", INACCESSIBLE, true },
};
/*
* ProtectHome=read-only table, protect $HOME and $XDG_RUNTIME_DIR and rest of
* system should be protected by ProtectSystem=
*/
static const TargetMount protect_home_read_only_table[] = {
{ "/home", READONLY, true },
{ "/run/user", READONLY, true },
{ "/root", READONLY, true },
};
/* ProtectHome=yes table */
static const TargetMount protect_home_yes_table[] = {
{ "/home", INACCESSIBLE, true },
{ "/run/user", INACCESSIBLE, true },
{ "/root", INACCESSIBLE, true },
};
/* ProtectSystem=yes table */
static const TargetMount protect_system_yes_table[] = {
{ "/usr", READONLY, false },
{ "/boot", READONLY, true },
{ "/efi", READONLY, true },
};
/* ProtectSystem=full includes ProtectSystem=yes */
static const TargetMount protect_system_full_table[] = {
{ "/usr", READONLY, false },
{ "/boot", READONLY, true },
{ "/efi", READONLY, true },
{ "/etc", READONLY, false },
};
/*
* ProtectSystem=strict table. In this strict mode, we mount everything
* read-only, except for /proc, /dev, /sys which are the kernel API VFS,
* which are left writable, but PrivateDevices= + ProtectKernelTunables=
* protect those, and these options should be fully orthogonal.
* (And of course /home and friends are also left writable, as ProtectHome=
* shall manage those, orthogonally).
*/
static const TargetMount protect_system_strict_table[] = {
{ "/", READONLY, false },
{ "/proc", READWRITE, false }, /* ProtectKernelTunables= */
{ "/sys", READWRITE, false }, /* ProtectKernelTunables= */
{ "/dev", READWRITE, false }, /* PrivateDevices= */
{ "/home", READWRITE, true }, /* ProtectHome= */
{ "/run/user", READWRITE, true }, /* ProtectHome= */
{ "/root", READWRITE, true }, /* ProtectHome= */
};
static void set_bind_mount(BindMount *p, char *path, MountMode mode, bool ignore) {
p->path = path;
p->mode = mode;
p->ignore = ignore;
}
static int append_one_mount(BindMount **p, const char *root_directory,
const char *path, MountMode mode, bool ignore) {
char *lpath;
assert(p);
lpath = prefix_root(root_directory, path);
if (!lpath)
return -ENOMEM;
set_bind_mount((*p)++, lpath, mode, ignore);
return 0;
}
static int append_mounts(BindMount **p, char **strv, MountMode mode) {
char **i;
assert(p);
STRV_FOREACH(i, strv) {
bool ignore = false;
char *path;
if (IN_SET(mode, INACCESSIBLE, READONLY, READWRITE) && startswith(*i, "-")) {
(*i)++;
ignore = true;
}
if (!path_is_absolute(*i))
return -EINVAL;
path = strdup(*i);
if (!path)
return -ENOMEM;
set_bind_mount((*p)++, path, mode, ignore);
}
return 0;
}
static int append_target_mounts(BindMount **p, const char *root_directory,
const TargetMount *mounts, const size_t size, bool ignore_protect) {
unsigned i;
assert(p);
assert(mounts);
for (i = 0; i < size; i++) {
bool ignore;
/*
* Here we assume that the ignore field is set during
* declaration we do not support "-" at the beginning.
*/
const TargetMount *m = &mounts[i];
char *path;
path = prefix_root(root_directory, m->path);
if (!path)
return -ENOMEM;
if (!path_is_absolute(path))
return -EINVAL;
/*
* Ignore paths if they are not present. First we use our
* static tables otherwise fallback to Unit context.
*/
ignore = m->ignore || ignore_protect;
set_bind_mount((*p)++, path, m->mode, ignore);
}
return 0;
}
static int append_protect_kernel_tunables(BindMount **p, const char *root_directory, bool ignore_protect) {
assert(p);
return append_target_mounts(p, root_directory, protect_kernel_tunables_table,
ELEMENTSOF(protect_kernel_tunables_table), ignore_protect);
}
static int append_protect_kernel_modules(BindMount **p, const char *root_directory, bool ignore_protect) {
assert(p);
return append_target_mounts(p, root_directory, protect_kernel_modules_table,
ELEMENTSOF(protect_kernel_modules_table), ignore_protect);
}
static int append_protect_home(BindMount **p, const char *root_directory, ProtectHome protect_home, bool ignore_protect) {
int r = 0;
assert(p);
if (protect_home == PROTECT_HOME_NO)
return 0;
switch (protect_home) {
case PROTECT_HOME_READ_ONLY:
r = append_target_mounts(p, root_directory, protect_home_read_only_table,
ELEMENTSOF(protect_home_read_only_table),
ignore_protect);
break;
case PROTECT_HOME_YES:
r = append_target_mounts(p, root_directory, protect_home_yes_table,
ELEMENTSOF(protect_home_yes_table), ignore_protect);
break;
default:
r = -EINVAL;
break;
}
return r;
}
static int append_protect_system(BindMount **p, const char *root_directory, ProtectSystem protect_system, bool ignore_protect) {
int r = 0;
assert(p);
if (protect_system == PROTECT_SYSTEM_NO)
return 0;
switch (protect_system) {
case PROTECT_SYSTEM_STRICT:
r = append_target_mounts(p, root_directory, protect_system_strict_table,
ELEMENTSOF(protect_system_strict_table), ignore_protect);
break;
case PROTECT_SYSTEM_YES:
r = append_target_mounts(p, root_directory, protect_system_yes_table,
ELEMENTSOF(protect_system_yes_table), ignore_protect);
break;
case PROTECT_SYSTEM_FULL:
r = append_target_mounts(p, root_directory, protect_system_full_table,
ELEMENTSOF(protect_system_full_table), ignore_protect);
break;
default:
r = -EINVAL;
break;
}
return r;
}
static int mount_path_compare(const void *a, const void *b) {
const BindMount *p = a, *q = b;
int d;
/* If the paths are not equal, then order prefixes first */
d = path_compare(p->path, q->path);
if (d != 0)
return d;
/* If the paths are equal, check the mode */
if (p->mode < q->mode)
return -1;
if (p->mode > q->mode)
return 1;
return 0;
}
static void drop_duplicates(BindMount *m, unsigned *n) {
BindMount *f, *t, *previous;
assert(m);
assert(n);
/* Drops duplicate entries. Expects that the array is properly ordered already. */
for (f = m, t = m, previous = NULL; f < m + *n; f++) {
/* The first one wins (which is the one with the more restrictive mode), see mount_path_compare()
* above. */
if (previous && path_equal(f->path, previous->path)) {
log_debug("%s is duplicate.", f->path);
f->path = mfree(f->path);
continue;
}
*t = *f;
previous = t;
t++;
}
*n = t - m;
}
static void drop_inaccessible(BindMount *m, unsigned *n) {
BindMount *f, *t;
const char *clear = NULL;
assert(m);
assert(n);
/* Drops all entries obstructed by another entry further up the tree. Expects that the array is properly
* ordered already. */
for (f = m, t = m; f < m + *n; f++) {
/* If we found a path set for INACCESSIBLE earlier, and this entry has it as prefix we should drop
* it, as inaccessible paths really should drop the entire subtree. */
if (clear && path_startswith(f->path, clear)) {
log_debug("%s is masked by %s.", f->path, clear);
f->path = mfree(f->path);
continue;
}
clear = f->mode == INACCESSIBLE ? f->path : NULL;
*t = *f;
t++;
}
*n = t - m;
}
static void drop_nop(BindMount *m, unsigned *n) {
BindMount *f, *t;
assert(m);
assert(n);
/* Drops all entries which have an immediate parent that has the same type, as they are redundant. Assumes the
* list is ordered by prefixes. */
for (f = m, t = m; f < m + *n; f++) {
/* Only suppress such subtrees for READONLY and READWRITE entries */
if (IN_SET(f->mode, READONLY, READWRITE)) {
BindMount *p;
bool found = false;
/* Now let's find the first parent of the entry we are looking at. */
for (p = t-1; p >= m; p--) {
if (path_startswith(f->path, p->path)) {
found = true;
break;
}
}
/* We found it, let's see if it's the same mode, if so, we can drop this entry */
if (found && p->mode == f->mode) {
log_debug("%s is redundant by %s", f->path, p->path);
f->path = mfree(f->path);
continue;
}
}
*t = *f;
t++;
}
*n = t - m;
}
static void drop_outside_root(const char *root_directory, BindMount *m, unsigned *n) {
BindMount *f, *t;
assert(m);
assert(n);
/* Nothing to do */
if (!root_directory)
return;
/* Drops all mounts that are outside of the root directory. */
for (f = m, t = m; f < m + *n; f++) {
if (!path_startswith(f->path, root_directory)) {
log_debug("%s is outside of root directory.", f->path);
f->path = mfree(f->path);
continue;
}
*t = *f;
t++;
}
*n = t - m;
}
static int mount_dev(BindMount *m) {
static const char devnodes[] =
"/dev/null\0"
"/dev/zero\0"
"/dev/full\0"
"/dev/random\0"
"/dev/urandom\0"
"/dev/tty\0";
char temporary_mount[] = "/tmp/namespace-dev-XXXXXX";
const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL;
_cleanup_umask_ mode_t u;
int r;
assert(m);
u = umask(0000);
if (!mkdtemp(temporary_mount))
return -errno;
dev = strjoina(temporary_mount, "/dev");
(void) mkdir(dev, 0755);
if (mount("tmpfs", dev, "tmpfs", DEV_MOUNT_OPTIONS, "mode=755") < 0) {
r = -errno;
goto fail;
}
devpts = strjoina(temporary_mount, "/dev/pts");
(void) mkdir(devpts, 0755);
if (mount("/dev/pts", devpts, NULL, MS_BIND, NULL) < 0) {
r = -errno;
goto fail;
}
devptmx = strjoina(temporary_mount, "/dev/ptmx");
if (symlink("pts/ptmx", devptmx) < 0) {
r = -errno;
goto fail;
}
devshm = strjoina(temporary_mount, "/dev/shm");
(void) mkdir(devshm, 01777);
r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL);
if (r < 0) {
r = -errno;
goto fail;
}
devmqueue = strjoina(temporary_mount, "/dev/mqueue");
(void) mkdir(devmqueue, 0755);
(void) mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL);
devhugepages = strjoina(temporary_mount, "/dev/hugepages");
(void) mkdir(devhugepages, 0755);
(void) mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL);
devlog = strjoina(temporary_mount, "/dev/log");
(void) symlink("/run/systemd/journal/dev-log", devlog);
NULSTR_FOREACH(d, devnodes) {
_cleanup_free_ char *dn = NULL;
struct stat st;
r = stat(d, &st);
if (r < 0) {
if (errno == ENOENT)
continue;
r = -errno;
goto fail;
}
if (!S_ISBLK(st.st_mode) &&
!S_ISCHR(st.st_mode)) {
r = -EINVAL;
goto fail;
}
if (st.st_rdev == 0)
continue;
dn = strappend(temporary_mount, d);
if (!dn) {
r = -ENOMEM;
goto fail;
}
mac_selinux_create_file_prepare(d, st.st_mode);
r = mknod(dn, st.st_mode, st.st_rdev);
mac_selinux_create_file_clear();
if (r < 0) {
r = -errno;
goto fail;
}
}
dev_setup(temporary_mount, UID_INVALID, GID_INVALID);
/* Create the /dev directory if missing. It is more likely to be
* missing when the service is started with RootDirectory. This is
* consistent with mount units creating the mount points when missing.
*/
(void) mkdir_p_label(m->path, 0755);
/* Unmount everything in old /dev */
umount_recursive(m->path, 0);
if (mount(dev, m->path, NULL, MS_MOVE, NULL) < 0) {
r = -errno;
goto fail;
}
rmdir(dev);
rmdir(temporary_mount);
return 0;
fail:
if (devpts)
umount(devpts);
if (devshm)
umount(devshm);
if (devhugepages)
umount(devhugepages);
if (devmqueue)
umount(devmqueue);
umount(dev);
rmdir(dev);
rmdir(temporary_mount);
return r;
}
static int apply_mount(
BindMount *m,
const char *tmp_dir,
const char *var_tmp_dir) {
const char *what;
int r;
assert(m);
log_debug("Applying namespace mount on %s", m->path);
switch (m->mode) {
case INACCESSIBLE: {
struct stat target;
/* First, get rid of everything that is below if there
* is anything... Then, overmount it with an
* inaccessible path. */
(void) umount_recursive(m->path, 0);
if (lstat(m->path, &target) < 0)
return log_debug_errno(errno, "Failed to lstat() %s to determine what to mount over it: %m", m->path);
what = mode_to_inaccessible_node(target.st_mode);
if (!what) {
log_debug("File type not supported for inaccessible mounts. Note that symlinks are not allowed");
return -ELOOP;
}
break;
}
case READONLY:
case READWRITE:
r = path_is_mount_point(m->path, 0);
if (r < 0)
return log_debug_errno(r, "Failed to determine whether %s is already a mount point: %m", m->path);
if (r > 0) /* Nothing to do here, it is already a mount. We just later toggle the MS_RDONLY bit for the mount point if needed. */
return 0;
/* This isn't a mount point yet, let's make it one. */
what = m->path;
break;
case PRIVATE_TMP:
what = tmp_dir;
break;
case PRIVATE_VAR_TMP:
what = var_tmp_dir;
break;
case PRIVATE_DEV:
return mount_dev(m);
default:
assert_not_reached("Unknown mode");
}
assert(what);
if (mount(what, m->path, NULL, MS_BIND|MS_REC, NULL) < 0)
return log_debug_errno(errno, "Failed to mount %s to %s: %m", what, m->path);
log_debug("Successfully mounted %s to %s", what, m->path);
return 0;
}
static int make_read_only(BindMount *m, char **blacklist) {
int r = 0;
assert(m);
if (IN_SET(m->mode, INACCESSIBLE, READONLY))
r = bind_remount_recursive(m->path, true, blacklist);
else if (m->mode == PRIVATE_DEV) { /* Can be readonly but the submounts can't*/
if (mount(NULL, m->path, NULL, MS_REMOUNT|DEV_MOUNT_OPTIONS|MS_RDONLY, NULL) < 0)
r = -errno;
} else
return 0;
/* Not that we only turn on the MS_RDONLY flag here, we never turn it off. Something that was marked read-only
* already stays this way. This improves compatibility with container managers, where we won't attempt to undo
* read-only mounts already applied. */
return r;
}
/* Chase symlinks and remove failed paths from mounts */
static int chase_all_symlinks(const char *root_directory, BindMount *m, unsigned *n) {
BindMount *f, *t;
int r = 0;
assert(m);
assert(n);
/* Since mount() will always follow symlinks and we need to take the different root directory into account we
* chase the symlinks on our own first. This call wil do so for all entries and remove all entries where we
* can't resolve the path, and which have been marked for such removal. */
for (f = m, t = m; f < m + *n; f++) {
int k;
_cleanup_free_ char *chased = NULL;
k = chase_symlinks(f->path, root_directory, &chased);
if (k < 0) {
/* Get only real errors */
if (r >= 0 && (k != -ENOENT || !f->ignore))
r = k;
log_debug_errno(r, "Failed to chase symlinks for %s: %m", f->path);
/* Doesn't exist or failed? Then remove it and continue! */
f->path = mfree(f->path);
continue;
}
if (!path_equal(f->path, chased)) {
log_debug("Chased %s → %s", f->path, chased);
free_and_replace(f->path, chased);
}
*t = *f;
t++;
}
*n = t - m;
return r;
}
static unsigned namespace_calculate_mounts(
const NameSpaceInfo *ns_info,
char** read_write_paths,
char** read_only_paths,
char** inaccessible_paths,
const char* tmp_dir,
const char* var_tmp_dir,
ProtectHome protect_home,
ProtectSystem protect_system) {
unsigned protect_home_cnt;
unsigned protect_system_cnt =
(protect_system == PROTECT_SYSTEM_STRICT ?
ELEMENTSOF(protect_system_strict_table) :
((protect_system == PROTECT_SYSTEM_FULL) ?
ELEMENTSOF(protect_system_full_table) :
((protect_system == PROTECT_SYSTEM_YES) ?
ELEMENTSOF(protect_system_yes_table) : 0)));
protect_home_cnt =
(protect_home == PROTECT_HOME_YES ?
ELEMENTSOF(protect_home_yes_table) :
((protect_home == PROTECT_HOME_READ_ONLY) ?
ELEMENTSOF(protect_home_read_only_table) : 0));
return !!tmp_dir + !!var_tmp_dir +
strv_length(read_write_paths) +
strv_length(read_only_paths) +
strv_length(inaccessible_paths) +
ns_info->private_dev +
(ns_info->protect_kernel_tunables ? ELEMENTSOF(protect_kernel_tunables_table) : 0) +
(ns_info->protect_control_groups ? 1 : 0) +
(ns_info->protect_kernel_modules ? ELEMENTSOF(protect_kernel_modules_table) : 0) +
protect_home_cnt + protect_system_cnt;
}
int setup_namespace(
const char* root_directory,
const NameSpaceInfo *ns_info,
char** read_write_paths,
char** read_only_paths,
char** inaccessible_paths,
const char* tmp_dir,
const char* var_tmp_dir,
ProtectHome protect_home,
ProtectSystem protect_system,
unsigned long mount_flags) {
BindMount *m, *mounts = NULL;
bool make_slave = false;
unsigned n_mounts;
int r = 0;
if (mount_flags == 0)
mount_flags = MS_SHARED;
n_mounts = namespace_calculate_mounts(ns_info,
read_write_paths,
read_only_paths,
inaccessible_paths,
tmp_dir, var_tmp_dir,
protect_home, protect_system);
/* Set mount slave mode */
if (root_directory || n_mounts > 0)
make_slave = true;
if (n_mounts > 0) {
m = mounts = (BindMount *) alloca0(n_mounts * sizeof(BindMount));
r = append_mounts(&m, read_write_paths, READWRITE);
if (r < 0)
goto finish;
r = append_mounts(&m, read_only_paths, READONLY);
if (r < 0)
goto finish;
r = append_mounts(&m, inaccessible_paths, INACCESSIBLE);
if (r < 0)
goto finish;
if (tmp_dir) {
r = append_one_mount(&m, root_directory, "/tmp", PRIVATE_TMP, false);
if (r < 0)
goto finish;
}
if (var_tmp_dir) {
r = append_one_mount(&m, root_directory, "/var/tmp", PRIVATE_VAR_TMP, false);
if (r < 0)
goto finish;
}
if (ns_info->private_dev) {
r = append_one_mount(&m, root_directory, "/dev", PRIVATE_DEV, false);
if (r < 0)
goto finish;
}
if (ns_info->protect_kernel_tunables) {
r = append_protect_kernel_tunables(&m, root_directory,
ns_info->ignore_protect_paths);
if (r < 0)
goto finish;
}
if (ns_info->protect_kernel_modules) {
r = append_protect_kernel_modules(&m, root_directory,
ns_info->ignore_protect_paths);
if (r < 0)
goto finish;
}
if (ns_info->protect_control_groups) {
r = append_one_mount(&m, root_directory, "/sys/fs/cgroup", READONLY, false);
if (r < 0)
goto finish;
}
r = append_protect_home(&m, root_directory, protect_home,
ns_info->ignore_protect_paths);
if (r < 0)
goto finish;
r = append_protect_system(&m, root_directory, protect_system, false);
if (r < 0)
goto finish;
assert(mounts + n_mounts == m);
/* Resolve symlinks manually first, as mount() will always follow them relative to the host's
* root. Moreover we want to suppress duplicates based on the resolved paths. This of course is a bit
* racy. */
r = chase_all_symlinks(root_directory, mounts, &n_mounts);
if (r < 0)
goto finish;
qsort(mounts, n_mounts, sizeof(BindMount), mount_path_compare);
drop_duplicates(mounts, &n_mounts);
drop_outside_root(root_directory, mounts, &n_mounts);
drop_inaccessible(mounts, &n_mounts);
drop_nop(mounts, &n_mounts);
}
if (unshare(CLONE_NEWNS) < 0) {
r = -errno;
goto finish;
}
if (make_slave) {
/* Remount / as SLAVE so that nothing now mounted in the namespace
shows up in the parent */
if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
r = -errno;
goto finish;
}
}
if (root_directory) {
/* Turn directory into bind mount, if it isn't one yet */
r = path_is_mount_point(root_directory, AT_SYMLINK_FOLLOW);
if (r < 0)
goto finish;
if (r == 0) {
if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0) {
r = -errno;
goto finish;
}
}
}
if (n_mounts > 0) {
char **blacklist;
unsigned j;
/* First round, add in all special mounts we need */
for (m = mounts; m < mounts + n_mounts; ++m) {
r = apply_mount(m, tmp_dir, var_tmp_dir);
if (r < 0)
goto finish;
}
/* Create a blacklist we can pass to bind_mount_recursive() */
blacklist = newa(char*, n_mounts+1);
for (j = 0; j < n_mounts; j++)
blacklist[j] = (char*) mounts[j].path;
blacklist[j] = NULL;
/* Second round, flip the ro bits if necessary. */
for (m = mounts; m < mounts + n_mounts; ++m) {
r = make_read_only(m, blacklist);
if (r < 0)
goto finish;
}
}
if (root_directory) {
/* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */
r = mount_move_root(root_directory);
if (r < 0)
goto finish;
}
/* Remount / as the desired mode. Not that this will not
* reestablish propagation from our side to the host, since
* what's disconnected is disconnected. */
if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
r = -errno;
goto finish;
}
r = 0;
finish:
for (m = mounts; m < mounts + n_mounts; m++)
free(m->path);
return r;
}
static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
_cleanup_free_ char *x = NULL;
char bid[SD_ID128_STRING_MAX];
sd_id128_t boot_id;
int r;
assert(id);
assert(prefix);
assert(path);
/* We include the boot id in the directory so that after a
* reboot we can easily identify obsolete directories. */
r = sd_id128_get_boot(&boot_id);
if (r < 0)
return r;
x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX");
if (!x)
return -ENOMEM;
RUN_WITH_UMASK(0077)
if (!mkdtemp(x))
return -errno;
RUN_WITH_UMASK(0000) {
char *y;
y = strjoina(x, "/tmp");
if (mkdir(y, 0777 | S_ISVTX) < 0)
return -errno;
}
*path = x;
x = NULL;
return 0;
}
int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
char *a, *b;
int r;
assert(id);
assert(tmp_dir);
assert(var_tmp_dir);
r = setup_one_tmp_dir(id, "/tmp", &a);
if (r < 0)
return r;
r = setup_one_tmp_dir(id, "/var/tmp", &b);
if (r < 0) {
char *t;
t = strjoina(a, "/tmp");
rmdir(t);
rmdir(a);
free(a);
return r;
}
*tmp_dir = a;
*var_tmp_dir = b;
return 0;
}
int setup_netns(int netns_storage_socket[2]) {
_cleanup_close_ int netns = -1;
int r, q;
assert(netns_storage_socket);
assert(netns_storage_socket[0] >= 0);
assert(netns_storage_socket[1] >= 0);
/* We use the passed socketpair as a storage buffer for our
* namespace reference fd. Whatever process runs this first
* shall create a new namespace, all others should just join
* it. To serialize that we use a file lock on the socket
* pair.
*
* It's a bit crazy, but hey, works great! */
if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
return -errno;
netns = receive_one_fd(netns_storage_socket[0], MSG_DONTWAIT);
if (netns == -EAGAIN) {
/* Nothing stored yet, so let's create a new namespace */
if (unshare(CLONE_NEWNET) < 0) {
r = -errno;
goto fail;
}
loopback_setup();
netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (netns < 0) {
r = -errno;
goto fail;
}
r = 1;
} else if (netns < 0) {
r = netns;
goto fail;
} else {
/* Yay, found something, so let's join the namespace */
if (setns(netns, CLONE_NEWNET) < 0) {
r = -errno;
goto fail;
}
r = 0;
}
q = send_one_fd(netns_storage_socket[1], netns, MSG_DONTWAIT);
if (q < 0) {
r = q;
goto fail;
}
fail:
(void) lockf(netns_storage_socket[0], F_ULOCK, 0);
return r;
}
static const char *const protect_home_table[_PROTECT_HOME_MAX] = {
[PROTECT_HOME_NO] = "no",
[PROTECT_HOME_YES] = "yes",
[PROTECT_HOME_READ_ONLY] = "read-only",
};
DEFINE_STRING_TABLE_LOOKUP(protect_home, ProtectHome);
static const char *const protect_system_table[_PROTECT_SYSTEM_MAX] = {
[PROTECT_SYSTEM_NO] = "no",
[PROTECT_SYSTEM_YES] = "yes",
[PROTECT_SYSTEM_FULL] = "full",
[PROTECT_SYSTEM_STRICT] = "strict",
};
DEFINE_STRING_TABLE_LOOKUP(protect_system, ProtectSystem);
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