From 2b4894764e9e92ae9004524ed466b4bdf94b2a34 Mon Sep 17 00:00:00 2001
From: Alban Crequy <alban@endocode.com>
Date: Mon, 18 May 2015 12:20:28 +0200
Subject: [PATCH] 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
Cherry-picked from: ee818b89f4890b3a00e93772249fce810f60811e
Resolves: #1421181
---
src/core/execute.c | 8 ++++--
src/core/namespace.c | 80 +++++++++++++++++++++++++++++++++++++++++++++-------
src/core/namespace.h | 3 +-
src/test/test-ns.c | 24 ++++++++++++++--
4 files changed, 100 insertions(+), 15 deletions(-)
diff --git a/src/core/execute.c b/src/core/execute.c
index 59340ec..863babd 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -1305,6 +1305,7 @@ static int exec_child(
uid_t uid = UID_INVALID;
gid_t gid = GID_INVALID;
int i, r;
+ bool needs_mount_namespace;
assert(command);
assert(context);
@@ -1593,7 +1594,9 @@ 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
@@ -1610,6 +1613,7 @@ 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,
@@ -1635,7 +1639,7 @@ 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;
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 00495c1..5747462 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -44,6 +44,7 @@
#include "label.h"
#include "selinux-util.h"
#include "namespace.h"
+#include "mkdir.h"
typedef enum MountMode {
/* This is ordered by priority! */
@@ -132,6 +133,22 @@ 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"
@@ -231,7 +248,13 @@ 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;
}
@@ -410,6 +433,7 @@ 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,
@@ -455,37 +479,56 @@ 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;
}
@@ -496,12 +539,20 @@ 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)
@@ -515,12 +566,21 @@ 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;
diff --git a/src/core/namespace.h b/src/core/namespace.h
index 42b92e7..00ab22b 100644
--- a/src/core/namespace.h
+++ b/src/core/namespace.h
@@ -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,
diff --git a/src/test/test-ns.c b/src/test/test-ns.c
index 7cd7b77..72a0004 100644
--- a/src/test/test-ns.c
+++ b/src/test/test-ns.c
@@ -42,10 +42,12 @@ 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",
@@ -54,7 +56,20 @@ 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,
@@ -66,6 +81,11 @@ 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;
}