inet: Sanitize inet{,6} protocol demux.

Don't pretend that inet_protos[] and inet6_protos[] are hashes, thay
are just a straight arrays.  Remove all unnecessary hash masking.

Document MAX_INET_PROTOS.

Use RAW_HTABLE_SIZE when appropriate.

Reported-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 10 insertions, 18 deletions

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 5247d5c..c7da142 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -600,9 +600,8 @@ static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
 {
 	const struct inet6_protocol *ipprot;
 	int inner_offset;
-	int hash;
-	u8 nexthdr;
 	__be16 frag_off;
+	u8 nexthdr;
 
 	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 		return;
@@ -629,10 +628,8 @@ static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
 	   --ANK (980726)
 	 */
 
-	hash = nexthdr & (MAX_INET_PROTOS - 1);
-
 	rcu_read_lock();
-	ipprot = rcu_dereference(inet6_protos[hash]);
+	ipprot = rcu_dereference(inet6_protos[nexthdr]);
 	if (ipprot && ipprot->err_handler)
 		ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
 	rcu_read_unlock();
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 21a15df..5ab923e 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -168,13 +168,12 @@ drop:
 
 static int ip6_input_finish(struct sk_buff *skb)
 {
+	struct net *net = dev_net(skb_dst(skb)->dev);
 	const struct inet6_protocol *ipprot;
+	struct inet6_dev *idev;
 	unsigned int nhoff;
 	int nexthdr;
 	bool raw;
-	u8 hash;
-	struct inet6_dev *idev;
-	struct net *net = dev_net(skb_dst(skb)->dev);
 
 	/*
 	 *	Parse extension headers
@@ -189,9 +188,7 @@ resubmit:
 	nexthdr = skb_network_header(skb)[nhoff];
 
 	raw = raw6_local_deliver(skb, nexthdr);
-
-	hash = nexthdr & (MAX_INET_PROTOS - 1);
-	if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
+	if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
 		int ret;
 
 		if (ipprot->flags & INET6_PROTO_FINAL) {
diff --git a/net/ipv6/protocol.c b/net/ipv6/protocol.c
index 9a7978f..053082d 100644
--- a/net/ipv6/protocol.c
+++ b/net/ipv6/protocol.c
@@ -29,9 +29,7 @@ const struct inet6_protocol __rcu *inet6_protos[MAX_INET_PROTOS] __read_mostly;
 
 int inet6_add_protocol(const struct inet6_protocol *prot, unsigned char protocol)
 {
-	int hash = protocol & (MAX_INET_PROTOS - 1);
-
-	return !cmpxchg((const struct inet6_protocol **)&inet6_protos[hash],
+	return !cmpxchg((const struct inet6_protocol **)&inet6_protos[protocol],
 			NULL, prot) ? 0 : -1;
 }
 EXPORT_SYMBOL(inet6_add_protocol);
@@ -42,9 +40,9 @@ EXPORT_SYMBOL(inet6_add_protocol);
 
 int inet6_del_protocol(const struct inet6_protocol *prot, unsigned char protocol)
 {
-	int ret, hash = protocol & (MAX_INET_PROTOS - 1);
+	int ret;
 
-	ret = (cmpxchg((const struct inet6_protocol **)&inet6_protos[hash],
+	ret = (cmpxchg((const struct inet6_protocol **)&inet6_protos[protocol],
 		       prot, NULL) == prot) ? 0 : -1;
 
 	synchronize_net();
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 43b0042..b5c1dcb 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -165,7 +165,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
 	saddr = &ipv6_hdr(skb)->saddr;
 	daddr = saddr + 1;
 
-	hash = nexthdr & (MAX_INET_PROTOS - 1);
+	hash = nexthdr & (RAW_HTABLE_SIZE - 1);
 
 	read_lock(&raw_v6_hashinfo.lock);
 	sk = sk_head(&raw_v6_hashinfo.ht[hash]);
@@ -229,7 +229,7 @@ bool raw6_local_deliver(struct sk_buff *skb, int nexthdr)
 {
 	struct sock *raw_sk;
 
-	raw_sk = sk_head(&raw_v6_hashinfo.ht[nexthdr & (MAX_INET_PROTOS - 1)]);
+	raw_sk = sk_head(&raw_v6_hashinfo.ht[nexthdr & (RAW_HTABLE_SIZE - 1)]);
 	if (raw_sk && !ipv6_raw_deliver(skb, nexthdr))
 		raw_sk = NULL;