af_packet: prevent information leak

[ Upstream commit 13fcb7bd322164c67926ffe272846d4860196dc6 ]

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: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 4021d47cc4379cb9b9e89b4ec6c318a536ffe1fc..4abde2d244571eeed77e13fc91ca01cec898b3f9 100644 (file)
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -59,6 +59,7 @@ struct tpacket_auxdata {
        __u16           tp_mac;
        __u16           tp_net;
        __u16           tp_vlan_tci;
+       __u16           tp_padding;
 };
 
 /* Rx ring - header status */
@@ -97,6 +98,7 @@ 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 24084ffe6609ef34ecdc99abd0eaa93151d8e6fa..39d85a9331093873d05ae4160064f68c828b93f3 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -759,6 +759,7 @@ 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:
@@ -1495,6 +1496,7 @@ 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);
        }