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core: Private*/Protect* options with RootDirectory 

When a service is chrooted with the option RootDirectory=/opt/..., then
the options PrivateDevices, PrivateTmp, ProtectHome, ProtectSystem must
mount the directories under $RootDirectory/{dev,tmp,home,usr,boot}.

The test-ns tool can test setup_namespace() with and without chroot:
 $ sudo TEST_NS_PROJECTS=/home/lennart/projects ./test-ns
 $ sudo TEST_NS_CHROOT=/home/alban/debian-tree TEST_NS_PROJECTS=/home/alban/debian-tree/home/alban/Documents ./test-ns
This commit is contained in:
Alban Crequy 2015-05-18 12:20:28 +02:00 committed by Lennart Poettering
parent a363680faa
commit ee818b89f4
4 changed files with 100 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/core/execute.c
View File

@ -1307,6 +1307,7 @@ static int exec_child(
uid_t uid = UID_INVALID;
gid_t gid = GID_INVALID;
int i, r;
bool needs_mount_namespace;
assert(unit);
assert(command);
@ -1585,7 +1586,9 @@ static int exec_child(
}
}
if (exec_needs_mount_namespace(context, params, runtime)) {
needs_mount_namespace = exec_needs_mount_namespace(context, params, runtime);
if (needs_mount_namespace) {
char *tmp = NULL, *var = NULL;
/* The runtime struct only contains the parent
@ -1602,6 +1605,7 @@ static int exec_child(
}
r = setup_namespace(
params->apply_chroot ? context->root_directory : NULL,
context->read_write_dirs,
context->read_only_dirs,
context->inaccessible_dirs,
@ -1627,7 +1631,7 @@ static int exec_child(
}
if (params->apply_chroot) {
if (context->root_directory)
if (!needs_mount_namespace && context->root_directory)
if (chroot(context->root_directory) < 0) {
*exit_status = EXIT_CHROOT;
return -errno;

80
src/core/namespace.c
View File

@ -36,6 +36,7 @@
#include "dev-setup.h"
#include "selinux-util.h"
#include "namespace.h"
#include "mkdir.h"
typedef enum MountMode {
/* This is ordered by priority! */
@ -124,6 +125,22 @@ static void drop_duplicates(BindMount *m, unsigned *n) {
*n = t - m;
}
static int mount_move_root(const char *path) {
if (chdir(path) < 0)
return -errno;
if (mount(path, "/", NULL, MS_MOVE, NULL) < 0)
return -errno;
if (chroot(".") < 0)
return -errno;
if (chdir("/") < 0)
return -errno;
return 0;
}
static int mount_dev(BindMount *m) {
static const char devnodes[] =
"/dev/null\0"
@ -225,7 +242,13 @@ static int mount_dev(BindMount *m) {
dev_setup(temporary_mount);
if (mount(dev, "/dev/", NULL, MS_MOVE, NULL) < 0) {
/* 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);
if (mount(dev, m->path, NULL, MS_MOVE, NULL) < 0) {
r = -errno;
goto fail;
}
@ -404,6 +427,7 @@ static int make_read_only(BindMount *m) {
}
int setup_namespace(
const char* root_directory,
char** read_write_dirs,
char** read_only_dirs,
char** inaccessible_dirs,
@ -449,37 +473,56 @@ int setup_namespace(
return r;
if (tmp_dir) {
m->path = "/tmp";
m->path = prefix_roota(root_directory, "/tmp");
m->mode = PRIVATE_TMP;
m++;
}
if (var_tmp_dir) {
m->path = "/var/tmp";
m->path = prefix_roota(root_directory, "/var/tmp");
m->mode = PRIVATE_VAR_TMP;
m++;
}
if (private_dev) {
m->path = "/dev";
m->path = prefix_roota(root_directory, "/dev");
m->mode = PRIVATE_DEV;
m++;
}
if (bus_endpoint_path) {
m->path = bus_endpoint_path;
m->path = prefix_roota(root_directory, bus_endpoint_path);
m->mode = PRIVATE_BUS_ENDPOINT;
m++;
}
if (protect_home != PROTECT_HOME_NO) {
r = append_mounts(&m, STRV_MAKE("-/home", "-/run/user", "-/root"), protect_home == PROTECT_HOME_READ_ONLY ? READONLY : INACCESSIBLE);
const char *home_dir, *run_user_dir, *root_dir;
home_dir = prefix_roota(root_directory, "/home");
home_dir = strjoina("-", home_dir);
run_user_dir = prefix_roota(root_directory, "/run/user");
run_user_dir = strjoina("-", run_user_dir);
root_dir = prefix_roota(root_directory, "/root");
root_dir = strjoina("-", root_dir);
r = append_mounts(&m, STRV_MAKE(home_dir, run_user_dir, root_dir),
protect_home == PROTECT_HOME_READ_ONLY ? READONLY : INACCESSIBLE);
if (r < 0)
return r;
}
if (protect_system != PROTECT_SYSTEM_NO) {
r = append_mounts(&m, protect_system == PROTECT_SYSTEM_FULL ? STRV_MAKE("/usr", "-/boot", "/etc") : STRV_MAKE("/usr", "-/boot"), READONLY);
const char *usr_dir, *boot_dir, *etc_dir;
usr_dir = prefix_roota(root_directory, "/home");
boot_dir = prefix_roota(root_directory, "/boot");
boot_dir = strjoina("-", boot_dir);
etc_dir = prefix_roota(root_directory, "/etc");
r = append_mounts(&m, protect_system == PROTECT_SYSTEM_FULL
? STRV_MAKE(usr_dir, boot_dir, etc_dir)
: STRV_MAKE(usr_dir, boot_dir), READONLY);
if (r < 0)
return r;
}
@ -490,12 +533,20 @@ int setup_namespace(
drop_duplicates(mounts, &n);
}
if (n > 0) {
if (n > 0 || root_directory) {
/* 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)
return -errno;
}
if (root_directory) {
/* Turn directory into bind mount */
if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0)
return -errno;
}
if (n > 0) {
for (m = mounts; m < mounts + n; ++m) {
r = apply_mount(m, tmp_dir, var_tmp_dir);
if (r < 0)
@ -509,12 +560,21 @@ int setup_namespace(
}
}
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);
/* at this point, we cannot rollback */
if (r < 0)
return r;
}
/* 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 fail;
/* at this point, we cannot rollback */
return -errno;
}
return 0;

3
src/core/namespace.h
View File

@ -41,7 +41,8 @@ typedef enum ProtectSystem {
_PROTECT_SYSTEM_INVALID = -1
} ProtectSystem;
int setup_namespace(char **read_write_dirs,
int setup_namespace(const char *chroot,
char **read_write_dirs,
char **read_only_dirs,
char **inaccessible_dirs,
const char *tmp_dir,

24
src/test/test-ns.c
View File

@ -38,10 +38,12 @@ int main(int argc, char *argv[]) {
NULL
};
const char * const inaccessible[] = {
const char *inaccessible[] = {
"/home/lennart/projects",
NULL
};
char *root_directory;
char *projects_directory;
int r;
char tmp_dir[] = "/tmp/systemd-private-XXXXXX",
@ -50,7 +52,20 @@ int main(int argc, char *argv[]) {
assert_se(mkdtemp(tmp_dir));
assert_se(mkdtemp(var_tmp_dir));
r = setup_namespace((char **) writable,
root_directory = getenv("TEST_NS_CHROOT");
projects_directory = getenv("TEST_NS_PROJECTS");
if (projects_directory)
inaccessible[0] = projects_directory;
log_info("Inaccessible directory: '%s'", inaccessible[0]);
if (root_directory)
log_info("Chroot: '%s'", root_directory);
else
log_info("Not chrooted");
r = setup_namespace(root_directory,
(char **) writable,
(char **) readonly,
(char **) inaccessible,
tmp_dir,
@ -62,6 +77,11 @@ int main(int argc, char *argv[]) {
0);
if (r < 0) {
log_error_errno(r, "Failed to setup namespace: %m");
log_info("Usage:\n"
" sudo TEST_NS_PROJECTS=/home/lennart/projects ./test-ns\n"
" sudo TEST_NS_CHROOT=/home/alban/debian-tree TEST_NS_PROJECTS=/home/alban/debian-tree/home/alban/Documents ./test-ns");
return 1;
}