netfilter: replace skb_make_writable with skb_ensure_writable

This converts all remaining users and then removes skb_make_writable.
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter.h

@@ -336,11 +336,6 @@ int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 		char __user *opt, int *len);
 #endif
 
-/* Call this before modifying an existing packet: ensures it is
-   modifiable and linear to the point you care about (writable_len).
-   Returns true or false. */
-int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
-
 struct flowi;
 struct nf_queue_entry;
 

net/netfilter/core.c

@@ -536,28 +536,6 @@ int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
 }
 EXPORT_SYMBOL(nf_hook_slow);
 
-
-int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
-{
-	if (writable_len > skb->len)
-		return 0;
-
-	/* Not exclusive use of packet?  Must copy. */
-	if (!skb_cloned(skb)) {
-		if (writable_len <= skb_headlen(skb))
-			return 1;
-	} else if (skb_clone_writable(skb, writable_len))
-		return 1;
-
-	if (writable_len <= skb_headlen(skb))
-		writable_len = 0;
-	else
-		writable_len -= skb_headlen(skb);
-
-	return !!__pskb_pull_tail(skb, writable_len);
-}
-EXPORT_SYMBOL(skb_make_writable);
-
 /* This needs to be compiled in any case to avoid dependencies between the
  * nfnetlink_queue code and nf_conntrack.
  */

net/netfilter/nf_synproxy_core.c

@@ -196,7 +196,7 @@ unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
 	optoff = protoff + sizeof(struct tcphdr);
 	optend = protoff + th->doff * 4;
 
-	if (!skb_make_writable(skb, optend))
+	if (skb_ensure_writable(skb, optend))
 		return 0;
 
 	while (optoff < optend) {

net/netfilter/nfnetlink_queue.c

@@ -863,7 +863,7 @@ nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e, int diff)
 		}
 		skb_put(e->skb, diff);
 	}
-	if (!skb_make_writable(e->skb, data_len))
+	if (skb_ensure_writable(e->skb, data_len))
 		return -ENOMEM;
 	skb_copy_to_linear_data(e->skb, data, data_len);
 	e->skb->ip_summed = CHECKSUM_NONE;

net/netfilter/xt_DSCP.c

@@ -34,7 +34,7 @@ dscp_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
 
 	if (dscp != dinfo->dscp) {
-		if (!skb_make_writable(skb, sizeof(struct iphdr)))
+		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
 			return NF_DROP;
 
 		ipv4_change_dsfield(ip_hdr(skb),
@@ -52,7 +52,7 @@ dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 	u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
 
 	if (dscp != dinfo->dscp) {
-		if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
+		if (skb_ensure_writable(skb, sizeof(struct ipv6hdr)))
 			return NF_DROP;
 
 		ipv6_change_dsfield(ipv6_hdr(skb),
@@ -82,7 +82,7 @@ tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
 
 	if (orig != nv) {
-		if (!skb_make_writable(skb, sizeof(struct iphdr)))
+		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
 			return NF_DROP;
 		iph = ip_hdr(skb);
 		ipv4_change_dsfield(iph, 0, nv);
@@ -102,7 +102,7 @@ tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 	nv   = (orig & ~info->tos_mask) ^ info->tos_value;
 
 	if (orig != nv) {
-		if (!skb_make_writable(skb, sizeof(struct iphdr)))
+		if (skb_ensure_writable(skb, sizeof(struct iphdr)))
 			return NF_DROP;
 		iph = ipv6_hdr(skb);
 		ipv6_change_dsfield(iph, 0, nv);