[PATCH v12 13/26] userns: Add pointer to ima_namespace to user_namespace

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 <[email protected]>
Acked-by: Christian Brauner <[email protected]>
Reviewed-by: Mimi Zohar <[email protected]>

---
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
+	struct ima_namespace	*ima_ns;
+#endif
 } __randomize_layout;
 
 struct ucounts {
diff --git a/kernel/user.c b/kernel/user.c
index e2cf8c22b539..e5d1f4b9b8ba 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -19,6 +19,7 @@
 #include <linux/export.h>
 #include <linux/user_namespace.h>
 #include <linux/proc_ns.h>
+#include <linux/ima.h>
 
 /*
  * userns count is 1 for root user, 1 for init_uts_ns,
@@ -67,6 +68,9 @@ struct user_namespace init_user_ns = {
 	.keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list),
 	.keyring_sem = __RWSEM_INITIALIZER(init_user_ns.keyring_sem),
 #endif
+#ifdef CONFIG_IMA_NS
+	.ima_ns = &init_ima_ns,
+#endif
 };
 EXPORT_SYMBOL_GPL(init_user_ns);
 
-- 
2.34.1