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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: 2feb27dbe0 ("[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>
This commit is contained in:
Congyu Liu 2022-01-18 14:20:13 -05:00 committed by Greg Kroah-Hartman
parent 20b7af4131
commit e372ecd455
3 changed files with 5 additions and 1 deletions
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1
include/linux/netdevice.h
View File

@ -2397,6 +2397,7 @@ 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;
};

3
net/core/net-procfs.c
View File

@ -252,7 +252,8 @@ 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

2
net/packet/af_packet.c
View File

@ -1715,6 +1715,7 @@ 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);
}
@ -3294,6 +3295,7 @@ 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;