af_packet: prevent information leak

commit 13fcb7bd322164c67926ffe272846d4860196dc6 upstream.

In 2.6.27, commit 393e52e33c6c2 (packet: deliver VLAN TCI to userspace)
added a small information leak.

Add padding field and make sure its zeroed before copy to user.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index aa57a5f993fc0257d343ba78b47fae46251cfa6f..9b8dc3a0942f3a2d893855241bea4e9eb116f26b 100644 (file)
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -60,6 +60,7 @@ struct tpacket_auxdata {
        __u16           tp_mac;
        __u16           tp_net;
        __u16           tp_vlan_tci;
+       __u16           tp_padding;
 };
 
 /* Rx ring - header status */
@@ -98,6 +99,7 @@ struct tpacket2_hdr {
        __u32           tp_sec;
        __u32           tp_nsec;
        __u16           tp_vlan_tci;
+       __u16           tp_padding;
 };
 
 #define TPACKET2_HDRLEN                (TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b1bc2d21c57f5ca884e72a5755cc46b59696d473..4096a66f6379e30d5e84cd0abddb3b4ea6ea8c79 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -751,6 +751,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
                h.h2->tp_sec = ts.tv_sec;
                h.h2->tp_nsec = ts.tv_nsec;
                h.h2->tp_vlan_tci = vlan_tx_tag_get(skb);
+               h.h2->tp_padding = 0;
                hdrlen = sizeof(*h.h2);
                break;
        default:
@@ -1617,6 +1618,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
                aux.tp_net = skb_network_offset(skb);
                aux.tp_vlan_tci = vlan_tx_tag_get(skb);
 
+               aux.tp_padding = 0;
                put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
        }