net: Use netlink_ns_capable to verify the permisions of netlink messages

It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.

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

3 files changed, 5 insertions, 5 deletions

diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index a603823a3e27..3b726f31c64c 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -574,7 +574,7 @@ static int dn_nl_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh)
         struct dn_ifaddr __rcu **ifap;
         int err = -EINVAL;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         if (!net_eq(net, &init_net))
@@ -618,7 +618,7 @@ static int dn_nl_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh)
         struct dn_ifaddr *ifa;
         int err;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         if (!net_eq(net, &init_net))
diff --git a/net/decnet/dn_fib.c b/net/decnet/dn_fib.c
index 57dc159245ec..d332aefb0846 100644
--- a/net/decnet/dn_fib.c
+++ b/net/decnet/dn_fib.c
@@ -505,7 +505,7 @@ static int dn_fib_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh)
         struct nlattr *attrs[RTA_MAX+1];
         int err;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         if (!net_eq(net, &init_net))
@@ -530,7 +530,7 @@ static int dn_fib_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh)
         struct nlattr *attrs[RTA_MAX+1];
         int err;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         if (!net_eq(net, &init_net))
diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c
index e83015cecfa7..e4d9560a910b 100644
--- a/net/decnet/netfilter/dn_rtmsg.c
+++ b/net/decnet/netfilter/dn_rtmsg.c
@@ -107,7 +107,7 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
         if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
                 return;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 RCV_SKB_FAIL(-EPERM);
 
         /* Eventually we might send routing messages too */