[NETFILTER]: Avoid skb_copy/pskb_copy/skb_realloc_headroom

This patch replaces unnecessary uses of skb_copy, pskb_copy and
skb_realloc_headroom by functions such as skb_make_writable and
pskb_expand_head.

This allows us to remove the double pointers later.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 21 insertions, 56 deletions

diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index b44192924f95..d1e3012d891f 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -3,6 +3,7 @@
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv4.h>
 #include <linux/ip.h>
+#include <linux/skbuff.h>
 #include <net/route.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
@@ -66,17 +67,10 @@ int ip_route_me_harder(struct sk_buff **pskb, unsigned addr_type)
 
         /* Change in oif may mean change in hh_len. */
         hh_len = (*pskb)->dst->dev->hard_header_len;
-        if (skb_headroom(*pskb) < hh_len) {
-                struct sk_buff *nskb;
-
-                nskb = skb_realloc_headroom(*pskb, hh_len);
-                if (!nskb)
-                        return -1;
-                if ((*pskb)->sk)
-                        skb_set_owner_w(nskb, (*pskb)->sk);
-                kfree_skb(*pskb);
-                *pskb = nskb;
-        }
+        if (skb_headroom(*pskb) < hh_len &&
+            pskb_expand_head(*pskb, hh_len - skb_headroom(*pskb), 0,
+                             GFP_ATOMIC))
+                return -1;
 
         return 0;
 }
@@ -107,17 +101,10 @@ int ip_xfrm_me_harder(struct sk_buff **pskb)
 
         /* Change in oif may mean change in hh_len. */
         hh_len = (*pskb)->dst->dev->hard_header_len;
-        if (skb_headroom(*pskb) < hh_len) {
-                struct sk_buff *nskb;
-
-                nskb = skb_realloc_headroom(*pskb, hh_len);
-                if (!nskb)
-                        return -1;
-                if ((*pskb)->sk)
-                        skb_set_owner_w(nskb, (*pskb)->sk);
-                kfree_skb(*pskb);
-                *pskb = nskb;
-        }
+        if (skb_headroom(*pskb) < hh_len &&
+            pskb_expand_head(*pskb, hh_len - skb_headroom(*pskb), 0,
+                             GFP_ATOMIC))
+                return -1;
         return 0;
 }
 EXPORT_SYMBOL(ip_xfrm_me_harder);
diff --git a/net/ipv4/netfilter/arpt_mangle.c b/net/ipv4/netfilter/arpt_mangle.c
index c4bdab47597f..0181f919a79c 100644
--- a/net/ipv4/netfilter/arpt_mangle.c
+++ b/net/ipv4/netfilter/arpt_mangle.c
@@ -1,5 +1,6 @@
 /* module that allows mangling of the arp payload */
 #include <linux/module.h>
+#include <linux/netfilter.h>
 #include <linux/netfilter_arp/arpt_mangle.h>
 #include <net/sock.h>
 
@@ -18,17 +19,8 @@ target(struct sk_buff **pskb,
         unsigned char *arpptr;
         int pln, hln;
 
-        if (skb_shared(*pskb) || skb_cloned(*pskb)) {
-                struct sk_buff *nskb;
-
-                nskb = skb_copy(*pskb, GFP_ATOMIC);
-                if (!nskb)
-                        return NF_DROP;
-                if ((*pskb)->sk)
-                        skb_set_owner_w(nskb, (*pskb)->sk);
-                kfree_skb(*pskb);
-                *pskb = nskb;
-        }
+        if (skb_make_writable(*pskb, (*pskb)->len))
+                return NF_DROP;
 
         arp = arp_hdr(*pskb);
         arpptr = skb_network_header(*pskb) + sizeof(*arp);
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 62d8867ca7d0..10a2ce09fd8e 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -335,6 +335,7 @@ static int
 ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
 {
         int diff;
+        int err;
         struct iphdr *user_iph = (struct iphdr *)v->payload;
 
         if (v->data_len < sizeof(*user_iph))
@@ -347,21 +348,14 @@ ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
                 if (v->data_len > 0xFFFF)
                         return -EINVAL;
                 if (diff > skb_tailroom(e->skb)) {
-                        struct sk_buff *newskb;
-
-                        newskb = skb_copy_expand(e->skb,
-                                                 skb_headroom(e->skb),
-                                                 diff,
-                                                 GFP_ATOMIC);
-                        if (newskb == NULL) {
-                                printk(KERN_WARNING "ip_queue: OOM "
-                                      "in mangle, dropping packet\n");
-                                return -ENOMEM;
+                        err = pskb_expand_head(e->skb, 0,
+                                               diff - skb_tailroom(e->skb),
+                                               GFP_ATOMIC);
+                        if (err) {
+                                printk(KERN_WARNING "ip_queue: error "
+                                      "in mangle, dropping packet: %d\n", -err);
+                                return err;
                         }
-                        if (e->skb->sk)
-                                skb_set_owner_w(newskb, e->skb->sk);
-                        kfree_skb(e->skb);
-                        e->skb = newskb;
                 }
                 skb_put(e->skb, diff);
         }
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
index 6e81f7612b71..40b429e4540d 100644
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ b/net/ipv4/netfilter/nf_nat_helper.c
@@ -113,20 +113,12 @@ static void mangle_contents(struct sk_buff *skb,
 /* Unusual, but possible case. */
 static int enlarge_skb(struct sk_buff **pskb, unsigned int extra)
 {
-        struct sk_buff *nskb;
-
         if ((*pskb)->len + extra > 65535)
                 return 0;
 
-        nskb = skb_copy_expand(*pskb, skb_headroom(*pskb), extra, GFP_ATOMIC);
-        if (!nskb)
+        if (pskb_expand_head(*pskb, 0, extra - skb_tailroom(*pskb), GFP_ATOMIC))
                 return 0;
 
-        /* Transfer socket to new skb. */
-        if ((*pskb)->sk)
-                skb_set_owner_w(nskb, (*pskb)->sk);
-        kfree_skb(*pskb);
-        *pskb = nskb;
         return 1;
 }