introduce cloning of fs_context

new primitive: vfs_dup_fs_context().  Comes with fs_context
method (->dup()) for copying the filesystem-specific parts
of fs_context, along with LSM one (->fs_context_dup()) for
doing the same to LSM parts.

[needs better commit message, and change of Author:, anyway]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 47ba4db4d8fb..356e78fe90a8 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -79,6 +79,11 @@
  * Security hooks for mount using fs_context.
  *	[See also Documentation/filesystems/mounting.txt]
  *
+ * @fs_context_dup:
+ *	Allocate and attach a security structure to sc->security.  This pointer
+ *	is initialised to NULL by the caller.
+ *	@fc indicates the new filesystem context.
+ *	@src_fc indicates the original filesystem context.
  * @fs_context_parse_param:
  *	Userspace provided a parameter to configure a superblock.  The LSM may
  *	reject it with an error and may use it for itself, in which case it
@@ -1470,6 +1475,7 @@ union security_list_options {
 	void (*bprm_committing_creds)(struct linux_binprm *bprm);
 	void (*bprm_committed_creds)(struct linux_binprm *bprm);
 
+	int (*fs_context_dup)(struct fs_context *fc, struct fs_context *src_sc);
 	int (*fs_context_parse_param)(struct fs_context *fc, struct fs_parameter *param);
 
 	int (*sb_alloc_security)(struct super_block *sb);
@@ -1813,6 +1819,7 @@ struct security_hook_heads {
 	struct hlist_head bprm_check_security;
 	struct hlist_head bprm_committing_creds;
 	struct hlist_head bprm_committed_creds;
+	struct hlist_head fs_context_dup;
 	struct hlist_head fs_context_parse_param;
 	struct hlist_head sb_alloc_security;
 	struct hlist_head sb_free_security;