On Sun, May 22, 2022 at 01:24:26PM -0500, Serge Hallyn wrote:
On Wed, Apr 20, 2022 at 10:06:20AM -0400, Stefan Berger wrote:
Add a pointer to ima_namespace to the user_namespace and initialize
the init_user_ns with a pointer to init_ima_ns. We need a pointer from
the user namespace to its associated IMA namespace since IMA namespaces
are piggybacking on user namespaces.
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Acked-by: Christian Brauner <brauner@xxxxxxxxxx>
Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
v11:
- Added lost A-b from Christian back
- Added sentence to patch description explaining why we need the pointer
v9:
- Deferred implementation of ima_ns_from_user_ns() to later patch
---
include/linux/ima.h | 2 ++
include/linux/user_namespace.h | 4 ++++
kernel/user.c | 4 ++++
3 files changed, 10 insertions(+)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 426b1744215e..fcb60a44e05f 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -14,6 +14,8 @@
#include <crypto/hash_info.h>
struct linux_binprm;
+extern struct ima_namespace init_ima_ns;
+
#ifdef CONFIG_IMA
extern enum hash_algo ima_get_current_hash_algo(void);
extern int ima_bprm_check(struct linux_binprm *bprm);
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 33a4240e6a6f..019e8cf7b633 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -36,6 +36,7 @@ struct uid_gid_map { /* 64 bytes -- 1 cache line */
#define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
struct ucounts;
+struct ima_namespace;
enum ucount_type {
UCOUNT_USER_NAMESPACES,
@@ -99,6 +100,9 @@ struct user_namespace {
#endif
struct ucounts *ucounts;
long ucount_max[UCOUNT_COUNTS];
+#ifdef CONFIG_IMA_NS
It's probably worth putting a comment here saying that user_ns does not
pin ima_ns.
That the only time the ima_ns will be freed is when user_ns is freed,
and only time it will be changed is when user_ns is freed, or during
ima_fs_ns_init() (under smp_load_acquire) during a new mount.
+ struct ima_namespace *ima_ns;
So, if I create a new user_ns with a new ima_ns, and in there I
create a new user_ns again, it looks like ima_ns will be NULL in
the new user_ns? Should it not be set to the parent->ima_ns?
(which would cause trouble for the way it's currently being
freed...)
Would also work and wouldn't be difficult to do imho.