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-rw-r--r--src/core/namespace.c187
1 files changed, 168 insertions, 19 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 834883267c..75dca5b791 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -30,6 +30,7 @@
#include "dev-setup.h"
#include "fd-util.h"
#include "fs-util.h"
+#include "loop-util.h"
#include "loopback-setup.h"
#include "missing.h"
#include "mkdir.h"
@@ -52,10 +53,13 @@ typedef enum MountMode {
INACCESSIBLE,
BIND_MOUNT,
BIND_MOUNT_RECURSIVE,
- READONLY,
PRIVATE_TMP,
PRIVATE_VAR_TMP,
PRIVATE_DEV,
+ BIND_DEV,
+ SYSFS,
+ PROCFS,
+ READONLY,
READWRITE,
} MountMode;
@@ -70,13 +74,13 @@ typedef struct MountEntry {
char *source_malloc;
} MountEntry;
-/*
- * 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.
- */
+/* If MountAPIVFS= is used, let's mount /sys and /proc into the it, but only as a fallback if the user hasn't mounted
+ * something there already. These mounts are hence overriden by any other explicitly configured mounts. */
+static const MountEntry apivfs_table[] = {
+ { "/proc", PROCFS, false },
+ { "/dev", BIND_DEV, false },
+ { "/sys", SYSFS, false },
+};
/* ProtectKernelTunables= option and the related filesystem APIs */
static const MountEntry protect_kernel_tunables_table[] = {
@@ -176,6 +180,13 @@ static const char *mount_entry_source(const MountEntry *p) {
return p->source_malloc ?: p->source_const;
}
+static void mount_entry_done(MountEntry *p) {
+ assert(p);
+
+ p->path_malloc = mfree(p->path_malloc);
+ p->source_malloc = mfree(p->source_malloc);
+}
+
static int append_access_mounts(MountEntry **p, char **strv, MountMode mode) {
char **i;
@@ -351,7 +362,7 @@ static void drop_duplicates(MountEntry *m, unsigned *n) {
if (previous && path_equal(mount_entry_path(f), mount_entry_path(previous))) {
log_debug("%s is duplicate.", mount_entry_path(f));
previous->read_only = previous->read_only || mount_entry_read_only(f); /* Propagate the read-only flag to the remaining entry */
- f->path_malloc = mfree(f->path_malloc);
+ mount_entry_done(f);
continue;
}
@@ -379,7 +390,7 @@ static void drop_inaccessible(MountEntry *m, unsigned *n) {
* it, as inaccessible paths really should drop the entire subtree. */
if (clear && path_startswith(mount_entry_path(f), clear)) {
log_debug("%s is masked by %s.", mount_entry_path(f), clear);
- f->path_malloc = mfree(f->path_malloc);
+ mount_entry_done(f);
continue;
}
@@ -419,7 +430,7 @@ static void drop_nop(MountEntry *m, unsigned *n) {
/* 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", mount_entry_path(f), mount_entry_path(p));
- f->path_malloc = mfree(f->path_malloc);
+ mount_entry_done(f);
continue;
}
}
@@ -447,7 +458,7 @@ static void drop_outside_root(const char *root_directory, MountEntry *m, unsigne
if (!path_startswith(mount_entry_path(f), root_directory)) {
log_debug("%s is outside of root directory.", mount_entry_path(f));
- f->path_malloc = mfree(f->path_malloc);
+ mount_entry_done(f);
continue;
}
@@ -458,7 +469,7 @@ static void drop_outside_root(const char *root_directory, MountEntry *m, unsigne
*n = t - m;
}
-static int mount_dev(MountEntry *m) {
+static int mount_private_dev(MountEntry *m) {
static const char devnodes[] =
"/dev/null\0"
"/dev/zero\0"
@@ -597,6 +608,62 @@ fail:
return r;
}
+static int mount_bind_dev(MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ /* Implements the little brother of mount_private_dev(): simply bind mounts the host's /dev into the service's
+ * /dev. This is only used when RootDirectory= is set. */
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /dev is already mounted: %m");
+ if (r > 0) /* make this a NOP if /dev is already a mount point */
+ return 0;
+
+ if (mount("/dev", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL) < 0)
+ return log_debug_errno(errno, "Failed to bind mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int mount_sysfs(MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /sys is already mounted: %m");
+ if (r > 0) /* make this a NOP if /sys is already a mount point */
+ return 0;
+
+ /* Bind mount the host's version so that we get all child mounts of it, too. */
+ if (mount("/sys", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL) < 0)
+ return log_debug_errno(errno, "Failed to mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int mount_procfs(MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /proc is already mounted: %m");
+ if (r > 0) /* make this a NOP if /proc is already a mount point */
+ return 0;
+
+ /* Mount a new instance, so that we get the one that matches our user namespace, if we are running in one */
+ if (mount("proc", mount_entry_path(m), "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) < 0)
+ return log_debug_errno(errno, "Failed to mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
static int mount_entry_chase(
const char *root_directory,
MountEntry *m,
@@ -684,6 +751,7 @@ static int apply_mount(
case BIND_MOUNT_RECURSIVE:
/* Also chase the source mount */
+
r = mount_entry_chase(root_directory, m, mount_entry_source(m), &m->source_malloc);
if (r <= 0)
return r;
@@ -700,7 +768,16 @@ static int apply_mount(
break;
case PRIVATE_DEV:
- return mount_dev(m);
+ return mount_private_dev(m);
+
+ case BIND_DEV:
+ return mount_bind_dev(m);
+
+ case SYSFS:
+ return mount_sysfs(m);
+
+ case PROCFS:
+ return mount_procfs(m);
default:
assert_not_reached("Unknown mode");
@@ -722,7 +799,7 @@ static int make_read_only(MountEntry *m, char **blacklist) {
if (mount_entry_read_only(m))
r = bind_remount_recursive(mount_entry_path(m), true, blacklist);
- else if (m->mode == PRIVATE_DEV) { /* Can be readonly but the submounts can't*/
+ else if (m->mode == PRIVATE_DEV) { /* Superblock can be readonly but the submounts can't*/
if (mount(NULL, mount_entry_path(m), NULL, MS_REMOUNT|DEV_MOUNT_OPTIONS|MS_RDONLY, NULL) < 0)
r = -errno;
} else
@@ -738,6 +815,17 @@ static int make_read_only(MountEntry *m, char **blacklist) {
return r;
}
+static bool namespace_info_mount_apivfs(const NameSpaceInfo *ns_info) {
+ assert(ns_info);
+
+ /* ProtectControlGroups= and ProtectKernelTunables= imply MountAPIVFS=, since to protect the API VFS mounts,
+ * they need to be around in the first place... */
+
+ return ns_info->mount_apivfs ||
+ ns_info->protect_control_groups ||
+ ns_info->protect_kernel_tunables;
+}
+
static unsigned namespace_calculate_mounts(
const NameSpaceInfo *ns_info,
char** read_write_paths,
@@ -774,11 +862,13 @@ static unsigned namespace_calculate_mounts(
(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;
+ protect_home_cnt + protect_system_cnt +
+ (namespace_info_mount_apivfs(ns_info) ? ELEMENTSOF(apivfs_table) : 0);
}
int setup_namespace(
const char* root_directory,
+ const char* root_image,
const NameSpaceInfo *ns_info,
char** read_write_paths,
char** read_only_paths,
@@ -789,16 +879,57 @@ int setup_namespace(
const char* var_tmp_dir,
ProtectHome protect_home,
ProtectSystem protect_system,
- unsigned long mount_flags) {
+ unsigned long mount_flags,
+ DissectImageFlags dissect_image_flags) {
+ _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+ _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+ _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
+ _cleanup_free_ void *root_hash = NULL;
MountEntry *m, *mounts = NULL;
+ size_t root_hash_size = 0;
bool make_slave = false;
unsigned n_mounts;
int r = 0;
+ assert(ns_info);
+
if (mount_flags == 0)
mount_flags = MS_SHARED;
+ if (root_image) {
+ dissect_image_flags |= DISSECT_IMAGE_REQUIRE_ROOT;
+
+ if (protect_system == PROTECT_SYSTEM_STRICT && strv_isempty(read_write_paths))
+ dissect_image_flags |= DISSECT_IMAGE_READ_ONLY;
+
+ r = loop_device_make_by_path(root_image,
+ dissect_image_flags & DISSECT_IMAGE_READ_ONLY ? O_RDONLY : O_RDWR,
+ &loop_device);
+ if (r < 0)
+ return r;
+
+ r = root_hash_load(root_image, &root_hash, &root_hash_size);
+ if (r < 0)
+ return r;
+
+ r = dissect_image(loop_device->fd, root_hash, root_hash_size, dissect_image_flags, &dissected_image);
+ if (r < 0)
+ return r;
+
+ r = dissected_image_decrypt(dissected_image, NULL, root_hash, root_hash_size, dissect_image_flags, &decrypted_image);
+ if (r < 0)
+ return r;
+
+ if (!root_directory) {
+ /* Create a mount point for the image, if it's still missing. We use the same mount point for
+ * all images, which is safe, since they all live in their own namespaces after all, and hence
+ * won't see each other. */
+ root_directory = "/run/systemd/unit-root";
+ (void) mkdir(root_directory, 0700);
+ }
+ }
+
n_mounts = namespace_calculate_mounts(
ns_info,
read_write_paths,
@@ -878,6 +1009,12 @@ int setup_namespace(
if (r < 0)
goto finish;
+ if (namespace_info_mount_apivfs(ns_info)) {
+ r = append_static_mounts(&m, apivfs_table, ELEMENTSOF(apivfs_table), ns_info->ignore_protect_paths);
+ if (r < 0)
+ goto finish;
+ }
+
assert(mounts + n_mounts == m);
/* Prepend the root directory where that's necessary */
@@ -907,7 +1044,19 @@ int setup_namespace(
}
}
- if (root_directory) {
+ if (root_image) {
+ r = dissected_image_mount(dissected_image, root_directory, dissect_image_flags);
+ if (r < 0)
+ goto finish;
+
+ r = decrypted_image_relinquish(decrypted_image);
+ if (r < 0)
+ goto finish;
+
+ loop_device_relinquish(loop_device);
+
+ } else if (root_directory) {
+
/* Turn directory into bind mount, if it isn't one yet */
r = path_is_mount_point(root_directory, NULL, AT_SYMLINK_FOLLOW);
if (r < 0)
@@ -964,7 +1113,7 @@ int setup_namespace(
finish:
for (m = mounts; m < mounts + n_mounts; m++)
- free(m->path_malloc);
+ mount_entry_done(m);
return r;
}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-29 04:38:57 +0000