net: fix information leakage in /proc/net/ptype

commit 47934e06b65637c88a762d9c98329ae6e3238888 upstream.

In one net namespace, after creating a packet socket without binding
it to a device, users in other net namespaces can observe the new
`packet_type` added by this packet socket by reading `/proc/net/ptype`
file. This is minor information leakage as packet socket is
namespace aware.

Add a net pointer in `packet_type` to keep the net namespace of
of corresponding packet socket. In `ptype_seq_show`, this net pointer
must be checked when it is not NULL.

Fixes: 2feb27dbe00c ("[NETNS]: Minor information leak via /proc/net/ptype file.")
Signed-off-by: Congyu Liu <liu3101@purdue.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2aacafe2bce58af1fa73ce5674162ef4150a7f37..a92fb5c5704f2ee639e1d136b7b3c3b2ddac4a73 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2237,6 +2237,7 @@ struct packet_type {
                                         struct net_device *);
        bool                    (*id_match)(struct packet_type *ptype,
                                            struct sock *sk);
+       struct net              *af_packet_net;
        void                    *af_packet_priv;
        struct list_head        list;
 };

diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c
index 14d09345f00d96ca6a54328c3da2564a5d51044a..af554597b35801091887c8910d193dd4c5eaadd4 100644 (file)
--- a/net/core/net-procfs.c
+++ b/net/core/net-procfs.c
@@ -278,7 +278,8 @@ static int ptype_seq_show(struct seq_file *seq, void *v)
 
        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "Type Device      Function\n");
-       else if (pt->dev == NULL || dev_net(pt->dev) == seq_file_net(seq)) {
+       else if ((!pt->af_packet_net || net_eq(pt->af_packet_net, seq_file_net(seq))) &&
+                (!pt->dev || net_eq(dev_net(pt->dev), seq_file_net(seq)))) {
                if (pt->type == htons(ETH_P_ALL))
                        seq_puts(seq, "ALL ");
                else

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 370d0a4af1f97dbfe0e544621087a64c6510711d..26f35b3abe980310515779e9657470304f667cf3 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1705,6 +1705,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
                match->prot_hook.dev = po->prot_hook.dev;
                match->prot_hook.func = packet_rcv_fanout;
                match->prot_hook.af_packet_priv = match;
+               match->prot_hook.af_packet_net = read_pnet(&match->net);
                match->prot_hook.id_match = match_fanout_group;
                list_add(&match->list, &fanout_list);
        }
@@ -3310,6 +3311,7 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
                po->prot_hook.func = packet_rcv_spkt;
 
        po->prot_hook.af_packet_priv = sk;
+       po->prot_hook.af_packet_net = sock_net(sk);
 
        if (proto) {
                po->prot_hook.type = proto;