1 files changed, 40 insertions, 0 deletions

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);