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6lowpan: Use skb_cow in IPHC decompression. 

Currently there are potentially 2 skb_copy_expand calls in IPHC
decompression.  This patch replaces this with one call to
skb_cow which will check to see if there is enough headroom
first to ensure it's only done if necessary and will handle
alignment issues for cache.
As skb_cow uses pskb_expand_head we ensure the skb isn't shared from
bluetooth and ieee802.15.4 code that use the IPHC decompression.

Signed-off-by: Martin Townsend <martin.townsend@xsilon.com>
Acked-by: Alexander Aring <alex.aring@gmail.com>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Martin Townsend 2014-10-13 11:00:56 +01:00 committed by Marcel Holtmann
parent 4456c50d23
commit 11e3ff7072
2 changed files with 25 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
net/6lowpan/iphc.c
View File

@ -174,30 +174,22 @@ static int uncompress_context_based_src_addr(struct sk_buff *skb,
static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
struct net_device *dev, skb_delivery_cb deliver_skb)
{
struct sk_buff *new;
int stat;
new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
GFP_ATOMIC);
kfree_skb(skb);
skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
skb_copy_to_linear_data(skb, hdr, sizeof(struct ipv6hdr));
if (!new)
return -ENOMEM;
skb_push(new, sizeof(struct ipv6hdr));
skb_reset_network_header(new);
skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
new->protocol = htons(ETH_P_IPV6);
new->pkt_type = PACKET_HOST;
new->dev = dev;
skb->protocol = htons(ETH_P_IPV6);
skb->pkt_type = PACKET_HOST;
skb->dev = dev;
raw_dump_table(__func__, "raw skb data dump before receiving",
new->data, new->len);
skb->data, skb->len);
stat = deliver_skb(new, dev);
stat = deliver_skb(skb, dev);
kfree_skb(new);
consume_skb(skb);
return stat;
}
@ -460,7 +452,7 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
/* UDP data uncompression */
if (iphc0 & LOWPAN_IPHC_NH_C) {
struct udphdr uh;
struct sk_buff *new;
const int needed = sizeof(struct udphdr) + sizeof(hdr);
if (uncompress_udp_header(skb, &uh))
goto drop;
@ -468,14 +460,11 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
/* replace the compressed UDP head by the uncompressed UDP
* header
*/
new = skb_copy_expand(skb, sizeof(struct udphdr),
skb_tailroom(skb), GFP_ATOMIC);
kfree_skb(skb);
if (!new)
return -ENOMEM;
skb = new;
err = skb_cow(skb, needed);
if (unlikely(err)) {
kfree_skb(skb);
return err;
}
skb_push(skb, sizeof(struct udphdr));
skb_reset_transport_header(skb);
@ -485,6 +474,12 @@ int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
(u8 *)&uh, sizeof(uh));
hdr.nexthdr = UIP_PROTO_UDP;
} else {
err = skb_cow(skb, sizeof(hdr));
if (unlikely(err)) {
kfree_skb(skb);
return err;
}
}
hdr.payload_len = htons(skb->len);

4
net/bluetooth/6lowpan.c
View File

@ -309,6 +309,10 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
if (dev->type != ARPHRD_6LOWPAN)
goto drop;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
goto drop;
/* check that it's our buffer */
if (skb->data[0] == LOWPAN_DISPATCH_IPV6) {
/* Copy the packet so that the IPv6 header is