sysctl: Infrastructure for per namespace sysctls

This patch implements the basic infrastructure for per namespace sysctls.

A list of lists of sysctl headers is added, allowing each namespace to have
it's own list of sysctl headers.

Each list of sysctl headers has a lookup function to find the first
sysctl header in the list, allowing the lists to have a per namespace
instance.

register_sysct_root is added to tell sysctl.c about additional
lists of sysctl_headers.  As all of the users are expected to be in
kernel no unregister function is provided.

sysctl_head_next is updated to walk through the list of lists.

__register_sysctl_paths is added to add a new sysctl table on
a non-default sysctl list.

The only intrusive part of this patch is propagating the information
to decided which list of sysctls to use for sysctl_check_table.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 1 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 77de3bfd8744..89faebfe48b8 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -945,7 +945,10 @@ enum
 
 /* For the /proc/sys support */
 struct ctl_table;
+struct nsproxy;
 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);
 
@@ -1049,6 +1052,13 @@ struct ctl_table
         void *extra2;
 };
 
+struct ctl_table_root {
+        struct list_head root_list;
+        struct list_head header_list;
+        struct list_head *(*lookup)(struct ctl_table_root *root,
+                                           struct nsproxy *namespaces);
+};
+
 /* struct ctl_table_header is used to maintain dynamic lists of
    struct ctl_table trees. */
 struct ctl_table_header
@@ -1058,6 +1068,7 @@ struct ctl_table_header
         int used;
         struct completion *unregistering;
         struct ctl_table *ctl_table_arg;
+        struct ctl_table_root *root;
 };
 
 /* struct ctl_path describes where in the hierarchy a table is added */
@@ -1066,12 +1077,16 @@ struct ctl_path {
         int ctl_name;
 };
 
+void register_sysctl_root(struct ctl_table_root *root);
+struct ctl_table_header *__register_sysctl_paths(
+        struct ctl_table_root *root, struct nsproxy *namespaces,
+        const struct ctl_path *path, struct ctl_table *table);
 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
                                                 struct ctl_table *table);
 
 void unregister_sysctl_table(struct ctl_table_header * table);
-int sysctl_check_table(struct ctl_table *table);
+int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table);
 
 #else /* __KERNEL__ */