This is a note to let you know that I've just added the patch titled net: fix information leakage in /proc/net/ptype to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-fix-information-leakage-in-proc-net-ptype.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4d97d82d94b218488b2e5d68d3b0e1ae60bd1891 Author: Congyu Liu <liu3101@xxxxxxxxxx> Date: Tue Jan 18 14:20:13 2022 -0500 net: fix information leakage in /proc/net/ptype [ Upstream commit 47934e06b65637c88a762d9c98329ae6e3238888 ] 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@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 3476d20b75d49..fe3155736d635 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2543,6 +2543,7 @@ 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 c714e6a9dad4c..e12c67f9492ba 100644 --- a/net/core/net-procfs.c +++ b/net/core/net-procfs.c @@ -263,7 +263,8 @@ 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 f78097aa403a8..6ef035494f30d 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1735,6 +1735,7 @@ static int fanout_add(struct sock *sk, struct fanout_args *args) 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; match->max_num_members = args->max_num_members; list_add(&match->list, &fanout_list); @@ -3323,6 +3324,7 @@ 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;