[NETFILTER]: {ip,ip6,nfnetlink}_queue: fix SKB_LINEAR_ASSERT when mangling packet data
As reported by Tomas Simonaitis <tomas.simonaitis@gmail.com>,
inserting new data in skbs queued over {ip,ip6,nfnetlink}_queue
triggers a SKB_LINEAR_ASSERT in skb_put().
Going back through the git history, it seems this bug is present since
at least 2.6.12-rc2, probably even since the removal of
skb_linearize() for netfilter.
Linearize non-linear skbs through skb_copy_expand() when enlarging
them. Tested by Thomas, fixes bugzilla #9933.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 6bda110..fe05da4 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -283,8 +283,8 @@
ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
{
int diff;
- int err;
struct iphdr *user_iph = (struct iphdr *)v->payload;
+ struct sk_buff *nskb;
if (v->data_len < sizeof(*user_iph))
return 0;
@@ -296,14 +296,16 @@
if (v->data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- err = pskb_expand_head(e->skb, 0,
+ nskb = skb_copy_expand(e->skb, 0,
diff - skb_tailroom(e->skb),
GFP_ATOMIC);
- if (err) {
+ if (!nskb) {
printk(KERN_WARNING "ip_queue: error "
- "in mangle, dropping packet: %d\n", -err);
- return err;
+ "in mangle, dropping packet\n");
+ return -ENOMEM;
}
+ kfree_skb(e->skb);
+ e->skb = nskb;
}
skb_put(e->skb, diff);
}
diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c
index e869916..cc2f9af 100644
--- a/net/ipv6/netfilter/ip6_queue.c
+++ b/net/ipv6/netfilter/ip6_queue.c
@@ -285,8 +285,8 @@
ipq_mangle_ipv6(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
{
int diff;
- int err;
struct ipv6hdr *user_iph = (struct ipv6hdr *)v->payload;
+ struct sk_buff *nskb;
if (v->data_len < sizeof(*user_iph))
return 0;
@@ -298,14 +298,16 @@
if (v->data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- err = pskb_expand_head(e->skb, 0,
+ nskb = skb_copy_expand(e->skb, 0,
diff - skb_tailroom(e->skb),
GFP_ATOMIC);
- if (err) {
+ if (!nskb) {
printk(KERN_WARNING "ip6_queue: OOM "
"in mangle, dropping packet\n");
- return err;
+ return -ENOMEM;
}
+ kfree_skb(e->skb);
+ e->skb = nskb;
}
skb_put(e->skb, diff);
}
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index a48b20f..0043d3a 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -443,8 +443,8 @@
static int
nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e)
{
+ struct sk_buff *nskb;
int diff;
- int err;
diff = data_len - e->skb->len;
if (diff < 0) {
@@ -454,14 +454,16 @@
if (data_len > 0xFFFF)
return -EINVAL;
if (diff > skb_tailroom(e->skb)) {
- err = pskb_expand_head(e->skb, 0,
+ nskb = skb_copy_expand(e->skb, 0,
diff - skb_tailroom(e->skb),
GFP_ATOMIC);
- if (err) {
+ if (!nskb) {
printk(KERN_WARNING "nf_queue: OOM "
"in mangle, dropping packet\n");
- return err;
+ return -ENOMEM;
}
+ kfree_skb(e->skb);
+ e->skb = nskb;
}
skb_put(e->skb, diff);
}