From: Congyu Liu liu3101@purdue.edu
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 --- include/linux/netdevice.h | 1 + net/core/net-procfs.c | 3 ++- net/packet/af_packet.c | 2 ++ 3 files changed, 5 insertions(+), 1 deletion(-)
--- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2346,6 +2346,7 @@ 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; }; --- a/net/core/net-procfs.c +++ b/net/core/net-procfs.c @@ -252,7 +252,8 @@ static int ptype_seq_show(struct seq_fil
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 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1716,6 +1716,7 @@ static int fanout_add(struct sock *sk, u 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); } @@ -3294,6 +3295,7 @@ static int packet_create(struct net *net 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;