net: avoid skb_warn_bad_offload false positives on UFO

[ Upstream commit 8d63bee643f1fb53e472f0e135cae4eb99d62d19 ]

skb_warn_bad_offload triggers a warning when an skb enters the GSO
stack at __skb_gso_segment that does not have CHECKSUM_PARTIAL
checksum offload set.

Commit b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
observed that SKB_GSO_DODGY producers can trigger the check and
that passing those packets through the GSO handlers will fix it
up. But, the software UFO handler will set ip_summed to
CHECKSUM_NONE.

When __skb_gso_segment is called from the receive path, this
triggers the warning again.

Make UFO set CHECKSUM_UNNECESSARY instead of CHECKSUM_NONE. On
Tx these two are equivalent. On Rx, this better matches the
skb state (checksum computed), as CHECKSUM_NONE here means no
checksum computed.

See also this thread for context:
http://patchwork.ozlabs.org/patch/799015/

Fixes: b2504a5dbef3 ("net: reduce skb_warn_bad_offload() noise")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 99b703e45c59f4107e5a2551e94ea0da3c6212da..22ad4e433b3a61481207f3c1ce04e809e5de83dd 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2436,7 +2436,7 @@ static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
 {
        if (tx_path)
                return skb->ip_summed != CHECKSUM_PARTIAL &&
-                      skb->ip_summed != CHECKSUM_NONE;
+                      skb->ip_summed != CHECKSUM_UNNECESSARY;
 
        return skb->ip_summed == CHECKSUM_NONE;
 }

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index e6d05ae1f22e6203c68fcdfca0c660b5a94f67c4..7a98b8d968c906c7172097e2cce8c97f0e3cb4aa 100644 (file)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -198,7 +198,7 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
        if (uh->check == 0)
                uh->check = CSUM_MANGLED_0;
 
-       skb->ip_summed = CHECKSUM_NONE;
+       skb->ip_summed = CHECKSUM_UNNECESSARY;
 
        /* Fragment the skb. IP headers of the fragments are updated in
         * inet_gso_segment()

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 050d556a79978fede957e2db20667993d8c366f5..3e2a55307b3d4c60e8f3bf3fff4beca68373c08e 100644 (file)
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -82,7 +82,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                if (uh->check == 0)
                        uh->check = CSUM_MANGLED_0;
 
-               skb->ip_summed = CHECKSUM_NONE;
+               skb->ip_summed = CHECKSUM_UNNECESSARY;
 
                /* Check if there is enough headroom to insert fragment header. */
                tnl_hlen = skb_tnl_header_len(skb);