tcp md5sig: Share MD5 Signature option parser between IPv4 and IPv6.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

4 files changed, 44 insertions, 73 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 633147cb6bbc..b1c4b78f1cb8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -399,6 +399,8 @@ extern void			tcp_parse_options(struct sk_buff *skb,
                                                   struct tcp_options_received *opt_rx,
                                                   int estab);
 
+extern u8                       *tcp_parse_md5sig_option(struct tcphdr *th);
+
 /*
  *      TCP v4 functions exported for the inet6 API
  */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index eba873e9b560..f331e67f2328 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3450,6 +3450,43 @@ static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
         return 1;
 }
 
+#ifdef CONFIG_TCP_MD5SIG
+/*
+ * Parse MD5 Signature option
+ */
+u8 *tcp_parse_md5sig_option(struct tcphdr *th)
+{
+        int length = (th->doff << 2) - sizeof (*th);
+        u8 *ptr = (u8*)(th + 1);
+
+        /* If the TCP option is too short, we can short cut */
+        if (length < TCPOLEN_MD5SIG)
+                return NULL;
+
+        while (length > 0) {
+                int opcode = *ptr++;
+                int opsize;
+
+                switch(opcode) {
+                case TCPOPT_EOL:
+                        return NULL;
+                case TCPOPT_NOP:
+                        length--;
+                        continue;
+                default:
+                        opsize = *ptr++;
+                        if (opsize < 2 || opsize > length)
+                                return NULL;
+                        if (opcode == TCPOPT_MD5SIG)
+                                return ptr;
+                }
+                ptr += opsize - 2;
+                length -= opsize;
+        }
+        return NULL;
+}
+#endif
+
 static inline void tcp_store_ts_recent(struct tcp_sock *tp)
 {
         tp->rx_opt.ts_recent = tp->rx_opt.rcv_tsval;
@@ -5467,6 +5504,9 @@ EXPORT_SYMBOL(sysctl_tcp_ecn);
 EXPORT_SYMBOL(sysctl_tcp_reordering);
 EXPORT_SYMBOL(sysctl_tcp_adv_win_scale);
 EXPORT_SYMBOL(tcp_parse_options);
+#ifdef CONFIG_TCP_MD5SIG
+EXPORT_SYMBOL(tcp_parse_md5sig_option);
+#endif
 EXPORT_SYMBOL(tcp_rcv_established);
 EXPORT_SYMBOL(tcp_rcv_state_process);
 EXPORT_SYMBOL(tcp_initialize_rcv_mss);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index cd601a866c2f..56f550933644 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1134,52 +1134,12 @@ static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
         struct tcp_md5sig_key *hash_expected;
         const struct iphdr *iph = ip_hdr(skb);
         struct tcphdr *th = tcp_hdr(skb);
-        int length = (th->doff << 2) - sizeof(struct tcphdr);
         int genhash;
-        unsigned char *ptr;
         unsigned char newhash[16];
 
         hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
+        hash_location = tcp_parse_md5sig_option(th);
 
-        /*
-         * If the TCP option length is less than the TCP_MD5SIG
-         * option length, then we can shortcut
-         */
-        if (length < TCPOLEN_MD5SIG) {
-                if (hash_expected)
-                        return 1;
-                else
-                        return 0;
-        }
-
-        /* Okay, we can't shortcut - we have to grub through the options */
-        ptr = (unsigned char *)(th + 1);
-        while (length > 0) {
-                int opcode = *ptr++;
-                int opsize;
-
-                switch (opcode) {
-                case TCPOPT_EOL:
-                        goto done_opts;
-                case TCPOPT_NOP:
-                        length--;
-                        continue;
-                default:
-                        opsize = *ptr++;
-                        if (opsize < 2)
-                                goto done_opts;
-                        if (opsize > length)
-                                goto done_opts;
-
-                        if (opcode == TCPOPT_MD5SIG) {
-                                hash_location = ptr;
-                                goto done_opts;
-                        }
-                }
-                ptr += opsize-2;
-                length -= opsize;
-        }
-done_opts:
         /* We've parsed the options - do we have a hash? */
         if (!hash_expected && !hash_location)
                 return 0;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 715965f0fac0..dd4ddb30a3a9 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -844,43 +844,12 @@ static int tcp_v6_inbound_md5_hash (struct sock *sk, struct sk_buff *skb)
         struct tcp_md5sig_key *hash_expected;
         struct ipv6hdr *ip6h = ipv6_hdr(skb);
         struct tcphdr *th = tcp_hdr(skb);
-        int length = (th->doff << 2) - sizeof (*th);
         int genhash;
-        u8 *ptr;
         u8 newhash[16];
 
         hash_expected = tcp_v6_md5_do_lookup(sk, &ip6h->saddr);
+        hash_location = tcp_parse_md5sig_option(th);
 
-        /* If the TCP option is too short, we can short cut */
-        if (length < TCPOLEN_MD5SIG)
-                return hash_expected ? 1 : 0;
-
-        /* parse options */
-        ptr = (u8*)(th + 1);
-        while (length > 0) {
-                int opcode = *ptr++;
-                int opsize;
-
-                switch(opcode) {
-                case TCPOPT_EOL:
-                        goto done_opts;
-                case TCPOPT_NOP:
-                        length--;
-                        continue;
-                default:
-                        opsize = *ptr++;
-                        if (opsize < 2 || opsize > length)
-                                goto done_opts;
-                        if (opcode == TCPOPT_MD5SIG) {
-                                hash_location = ptr;
-                                goto done_opts;
-                        }
-                }
-                ptr += opsize - 2;
-                length -= opsize;
-        }
-
-done_opts:
         /* do we have a hash as expected? */
         if (!hash_expected) {
                 if (!hash_location)