sysctl: add the ->permissions callback on the ctl_table_root

When reading from/writing to some table, a root, which this table came from,
may affect this table's permissions, depending on who is working with the
table.

The core hunk is at the bottom of this patch.  All the rest is just pushing
the ctl_table_root argument up to the sysctl_perm() function.

This will be mostly (only?) used in the net sysctls.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Denis V. Lunev <den@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 39eafd8..24141b4 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -945,11 +945,14 @@ enum
 /* For the /proc/sys support */
 struct ctl_table;
 struct nsproxy;
+struct ctl_table_root;
+
 extern struct ctl_table_header *sysctl_head_next(struct ctl_table_header *prev);
 extern struct ctl_table_header *__sysctl_head_next(struct nsproxy *namespaces,
 						struct ctl_table_header *prev);
 extern void sysctl_head_finish(struct ctl_table_header *prev);
-extern int sysctl_perm(struct ctl_table *table, int op);
+extern int sysctl_perm(struct ctl_table_root *root,
+		struct ctl_table *table, int op);
 
 typedef struct ctl_table ctl_table;
 
@@ -1049,6 +1052,8 @@ struct ctl_table_root {
 	struct list_head header_list;
 	struct list_head *(*lookup)(struct ctl_table_root *root,
 					   struct nsproxy *namespaces);
+	int (*permissions)(struct ctl_table_root *root,
+			struct nsproxy *namespaces, struct ctl_table *table);
 };
 
 /* struct ctl_table_header is used to maintain dynamic lists of