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, 14 insertions, 11 deletions

diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index d8a5558a47b4..c3206fa50048 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -1342,7 +1342,8 @@ static void sysctl_repair_table(struct ctl_table *table)
         }
 }
 
-static struct ctl_table *sysctl_check_lookup(struct ctl_table *table)
+static struct ctl_table *sysctl_check_lookup(struct nsproxy *namespaces,
+                                                struct ctl_table *table)
 {
         struct ctl_table_header *head;
         struct ctl_table *ref, *test;
@@ -1350,8 +1351,8 @@ static struct ctl_table *sysctl_check_lookup(struct ctl_table *table)
 
         depth = sysctl_depth(table);
 
-        for (head = sysctl_head_next(NULL); head;
-             head = sysctl_head_next(head)) {
+        for (head = __sysctl_head_next(namespaces, NULL); head;
+             head = __sysctl_head_next(namespaces, head)) {
                 cur_depth = depth;
                 ref = head->ctl_table;
 repeat:
@@ -1396,13 +1397,14 @@ static void set_fail(const char **fail, struct ctl_table *table, const char *str
         *fail = str;
 }
 
-static int sysctl_check_dir(struct ctl_table *table)
+static int sysctl_check_dir(struct nsproxy *namespaces,
+                                struct ctl_table *table)
 {
         struct ctl_table *ref;
         int error;
 
         error = 0;
-        ref = sysctl_check_lookup(table);
+        ref = sysctl_check_lookup(namespaces, table);
         if (ref) {
                 int match = 0;
                 if ((!table->procname && !ref->procname) ||
@@ -1427,11 +1429,12 @@ static int sysctl_check_dir(struct ctl_table *table)
         return error;
 }
 
-static void sysctl_check_leaf(struct ctl_table *table, const char **fail)
+static void sysctl_check_leaf(struct nsproxy *namespaces,
+                                struct ctl_table *table, const char **fail)
 {
         struct ctl_table *ref;
 
-        ref = sysctl_check_lookup(table);
+        ref = sysctl_check_lookup(namespaces, table);
         if (ref && (ref != table))
                 set_fail(fail, table, "Sysctl already exists");
 }
@@ -1455,7 +1458,7 @@ static void sysctl_check_bin_path(struct ctl_table *table, const char **fail)
         }
 }
 
-int sysctl_check_table(struct ctl_table *table)
+int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *table)
 {
         int error = 0;
         for (; table->ctl_name || table->procname; table++) {
@@ -1485,7 +1488,7 @@ int sysctl_check_table(struct ctl_table *table)
                                 set_fail(&fail, table, "Directory with extra1");
                         if (table->extra2)
                                 set_fail(&fail, table, "Directory with extra2");
-                        if (sysctl_check_dir(table))
+                        if (sysctl_check_dir(namespaces, table))
                                 set_fail(&fail, table, "Inconsistent directory names");
                 } else {
                         if ((table->strategy == sysctl_data) ||
@@ -1534,7 +1537,7 @@ int sysctl_check_table(struct ctl_table *table)
                         if (!table->procname && table->proc_handler)
                                 set_fail(&fail, table, "proc_handler without procname");
 #endif
-                        sysctl_check_leaf(table, &fail);
+                        sysctl_check_leaf(namespaces, table, &fail);
                 }
                 sysctl_check_bin_path(table, &fail);
                 if (fail) {
@@ -1542,7 +1545,7 @@ int sysctl_check_table(struct ctl_table *table)
                         error = -EINVAL;
                 }
                 if (table->child)
-                        error |= sysctl_check_table(table->child);
+                        error |= sysctl_check_table(namespaces, table->child);
         }
         return error;
 }