This is a note to let you know that I've just added the patch titled
fs,security: Add sb_delete hook
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-security-add-sb_delete-hook.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d46fe169d6c766a600e6037e8fa87ac94d0f8bd8
Author: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
Date: Thu Apr 22 17:41:16 2021 +0200
fs,security: Add sb_delete hook
[ Upstream commit 83e804f0bfee2247b1c0aa64845c81a38562da7a ]
The sb_delete security hook is called when shutting down a superblock,
which may be useful to release kernel objects tied to the superblock's
lifetime (e.g. inodes).
This new hook is needed by Landlock to release (ephemerally) tagged
struct inodes. This comes from the unprivileged nature of Landlock
described in the next commit.
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jann Horn <jannh@xxxxxxxxxx>
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210422154123.13086-7-mic@xxxxxxxxxxx
Signed-off-by: James Morris <jamorris@xxxxxxxxxxxxxxxxxxx>
Stable-dep-of: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/super.c b/fs/super.c
index bae3fe80f852..705be5d0600e 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -454,6 +454,7 @@ void generic_shutdown_super(struct super_block *sb)
evict_inodes(sb);
/* only nonzero refcount inodes can have marks */
fsnotify_sb_delete(sb);
+ security_sb_delete(sb);
if (sb->s_dio_done_wq) {
destroy_workqueue(sb->s_dio_done_wq);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index d13631a5e908..d74ffcdc7be6 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -59,6 +59,7 @@ LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc,
LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc,
struct fs_parameter *param)
LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
+LSM_HOOK(void, LSM_RET_VOID, sb_delete, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 64cdf4d7bfb3..73abbdd94c13 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -108,6 +108,9 @@
* allocated.
* @sb contains the super_block structure to be modified.
* Return 0 if operation was successful.
+ * @sb_delete:
+ * Release objects tied to a superblock (e.g. inodes).
+ * @sb contains the super_block structure being released.
* @sb_free_security:
* Deallocate and clear the sb->s_security field.
* @sb contains the super_block structure to be modified.
diff --git a/include/linux/security.h b/include/linux/security.h
index e9b4b5410614..f37087d76913 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -290,6 +290,7 @@ void security_bprm_committed_creds(struct linux_binprm *bprm);
int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc);
int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param);
int security_sb_alloc(struct super_block *sb);
+void security_sb_delete(struct super_block *sb);
void security_sb_free(struct super_block *sb);
void security_free_mnt_opts(void **mnt_opts);
int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
@@ -622,6 +623,9 @@ static inline int security_sb_alloc(struct super_block *sb)
return 0;
}
+static inline void security_sb_delete(struct super_block *sb)
+{ }
+
static inline void security_sb_free(struct super_block *sb)
{ }
diff --git a/security/security.c b/security/security.c
index 8ea826ea6167..771ec21a6e0b 100644
--- a/security/security.c
+++ b/security/security.c
@@ -885,6 +885,11 @@ int security_sb_alloc(struct super_block *sb)
return call_int_hook(sb_alloc_security, 0, sb);
}
+void security_sb_delete(struct super_block *sb)
+{
+ call_void_hook(sb_delete, sb);
+}
+
void security_sb_free(struct super_block *sb)
{
call_void_hook(sb_free_security, sb);
