diff options
authorMichal Kubeček <mkubecek@suse.cz>2015-03-02 18:27:11 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-18 13:22:27 +0100
commit6b3130085888b4f1866d57dc19175bbd283a36a3 (patch)
parent538022e1ce05a1ebadfbd916413c1712593a1fdc (diff)
udp: only allow UFO for packets from SOCK_DGRAM sockets
[ Upstream commit acf8dd0a9d0b9e4cdb597c2f74802f79c699e802 ] If an over-MTU UDP datagram is sent through a SOCK_RAW socket to a UFO-capable device, ip_ufo_append_data() sets skb->ip_summed to CHECKSUM_PARTIAL unconditionally as all GSO code assumes transport layer checksum is to be computed on segmentation. However, in this case, skb->csum_start and skb->csum_offset are never set as raw socket transmit path bypasses udp_send_skb() where they are usually set. As a result, driver may access invalid memory when trying to calculate the checksum and store the result (as observed in virtio_net driver). Moreover, the very idea of modifying the userspace provided UDP header is IMHO against raw socket semantics (I wasn't able to find a document clearly stating this or the opposite, though). And while allowing CHECKSUM_NONE in the UFO case would be more efficient, it would be a bit too intrusive change just to handle a corner case like this. Therefore disallowing UFO for packets from SOCK_DGRAM seems to be the best option. Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 4 insertions, 2 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index def18547748e..57e745086302 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -845,7 +845,8 @@ static int __ip_append_data(struct sock *sk,
cork->length += length;
if (((length > mtu) || (skb && skb_has_frags(skb))) &&
(sk->sk_protocol == IPPROTO_UDP) &&
- (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
+ (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
+ (sk->sk_type == SOCK_DGRAM)) {
err = ip_ufo_append_data(sk, queue, getfrag, from, length,
hh_len, fragheaderlen, transhdrlen,
maxfraglen, flags);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 071edcba4158..1ce7ea1f40b7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1286,7 +1286,8 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
if (((length > mtu) ||
(skb && skb_has_frags(skb))) &&
(sk->sk_protocol == IPPROTO_UDP) &&
- (rt->dst.dev->features & NETIF_F_UFO)) {
+ (rt->dst.dev->features & NETIF_F_UFO) &&
+ (sk->sk_type == SOCK_DGRAM)) {
err = ip6_ufo_append_data(sk, getfrag, from, length,
hh_len, fragheaderlen,
transhdrlen, mtu, flags, rt);