net: Don't export sysctls to unprivileged users

In preparation for supporting the creation of network namespaces
by unprivileged users, modify all of the per net sysctl exports
and refuse to allow them to unprivileged users.

This makes it safe for unprivileged users in general to access
per net sysctls, and allows sysctls to be exported to unprivileged
users on an individual basis as they are deemed safe.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index b4a9fd51dae7..d77dc1e2a42b 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -967,9 +967,14 @@ struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
                         sizeof(ipv6_icmp_table_template),
                         GFP_KERNEL);
 
-        if (table)
+        if (table) {
                 table[0].data = &net->ipv6.sysctl.icmpv6_time;
 
+                /* Don't export sysctls to unprivileged users */
+                if (net->user_ns != &init_user_ns)
+                        table[0].procname = NULL;
+        }
+
         return table;
 }
 #endif