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| author | Michal Kubeček <mkubecek@suse.cz> | 2015-03-02 18:27:11 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 13:31:23 +0100 |
| commit | 8a0cafc9a8131cc545dc9924aed38f7176ee4ad7 (patch) | |
| tree | b898bdb1eded41660c035d2bcb1da6a8e10b5357 /net/ipv4 | |
| parent | 37aa4dd0a138bc88e42ca02a909367b12042fddf (diff) | |
| download | lwn-8a0cafc9a8131cc545dc9924aed38f7176ee4ad7.tar.gz lwn-8a0cafc9a8131cc545dc9924aed38f7176ee4ad7.zip | |
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>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/ip_output.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index dd637fc4b553..05686c47a289 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -843,7 +843,8 @@ static int __ip_append_data(struct sock *sk, cork->length += length; if (((length > mtu) || (skb && skb_is_gso(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); |