RE: [PATCH 3/3] secure_seq: use fast siphash instead of slow md5

[David Laight]

From: Jason A. Donenfeld
> Sent: 14 December 2016 00:17
> This gives a clear speed and security improvement. Rather than manually
> filling MD5 buffers, we simply create a layout by a simple anonymous
> struct, for which gcc generates rather efficient code.
...
> + const struct {
> + struct in6_addr saddr;
> + struct in6_addr daddr;
> + __be16 sport;
> + __be16 dport;
> + } __packed combined = {
> + .saddr = *(struct in6_addr *)saddr,
> + .daddr = *(struct in6_addr *)daddr,
> + .sport = sport,
> + .dport = dport
> + };

You need to look at the effect of marking this (and the other)
structures 'packed' on architectures like sparc64.

David

[PATCH 3/3] secure_seq: use fast siphash instead of slow md5

[Jason A. Donenfeld]

This gives a clear speed and security improvement. Rather than manually
filling MD5 buffers, we simply create a layout by a simple anonymous
struct, for which gcc generates rather efficient code.

Signed-off-by: Jason A. Donenfeld 
---
 net/core/secure_seq.c | 153 --
 1 file changed, 73 insertions(+), 80 deletions(-)

diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
index fd3ce461fbe6..dcee974f2fb1 100644
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -1,3 +1,5 @@
+/* Copyright (C) 2016 Jason A. Donenfeld . All Rights 
Reserved. */
+
 #include 
 #include 
 #include 
@@ -8,13 +10,12 @@
 #include 
 #include 
 #include 
-
+#include 
+#include 
 #include 
 
 #if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)
-#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)
-
-static u32 net_secret[NET_SECRET_SIZE] cacheline_aligned;
+static u8 net_secret[SIPHASH24_KEY_LEN];
 
 static __always_inline void net_secret_init(void)
 {
@@ -43,43 +44,36 @@ static u32 seq_scale(u32 seq)
 __u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
   __be16 sport, __be16 dport)
 {
-   u32 secret[MD5_MESSAGE_BYTES / 4];
-   u32 hash[MD5_DIGEST_WORDS];
-   u32 i;
-
+   const struct {
+   struct in6_addr saddr;
+   struct in6_addr daddr;
+   __be16 sport;
+   __be16 dport;
+   } __packed combined = {
+   .saddr = *(struct in6_addr *)saddr,
+   .daddr = *(struct in6_addr *)daddr,
+   .sport = sport,
+   .dport = dport
+   };
net_secret_init();
-   memcpy(hash, saddr, 16);
-   for (i = 0; i < 4; i++)
-   secret[i] = net_secret[i] + (__force u32)daddr[i];
-   secret[4] = net_secret[4] +
-   (((__force u16)sport << 16) + (__force u16)dport);
-   for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
-   secret[i] = net_secret[i];
-
-   md5_transform(hash, secret);
-
-   return seq_scale(hash[0]);
+   return seq_scale(siphash24((const u8 *), sizeof(combined), 
net_secret));
 }
 EXPORT_SYMBOL(secure_tcpv6_sequence_number);
 
 u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
   __be16 dport)
 {
-   u32 secret[MD5_MESSAGE_BYTES / 4];
-   u32 hash[MD5_DIGEST_WORDS];
-   u32 i;
-
+   const struct {
+   struct in6_addr saddr;
+   struct in6_addr daddr;
+   __be16 dport;
+   } __packed combined = {
+   .saddr = *(struct in6_addr *)saddr,
+   .daddr = *(struct in6_addr *)daddr,
+   .dport = dport
+   };
net_secret_init();
-   memcpy(hash, saddr, 16);
-   for (i = 0; i < 4; i++)
-   secret[i] = net_secret[i] + (__force u32) daddr[i];
-   secret[4] = net_secret[4] + (__force u32)dport;
-   for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
-   secret[i] = net_secret[i];
-
-   md5_transform(hash, secret);
-
-   return hash[0];
+   return siphash24((const u8 *), sizeof(combined), net_secret);
 }
 EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
 #endif
@@ -89,32 +83,34 @@ EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
 __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
 __be16 sport, __be16 dport)
 {
-   u32 hash[MD5_DIGEST_WORDS];
-
+   const struct {
+   __be32 saddr;
+   __be32 daddr;
+   __be16 sport;
+   __be16 dport;
+   } __packed combined = {
+   .saddr = saddr,
+   .daddr = daddr,
+   .sport = sport,
+   .dport = dport
+   };
net_secret_init();
-   hash[0] = (__force u32)saddr;
-   hash[1] = (__force u32)daddr;
-   hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
-   hash[3] = net_secret[15];
-
-   md5_transform(hash, net_secret);
-
-   return seq_scale(hash[0]);
+   return seq_scale(siphash24((const u8 *), sizeof(combined), 
net_secret));
 }
 
 u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
 {
-   u32 hash[MD5_DIGEST_WORDS];
-
+   const struct {
+   __be32 saddr;
+   __be32 daddr;
+   __be16 dport;
+   } __packed combined = {
+   .saddr = saddr,
+   .daddr = daddr,
+   .dport = dport
+   };
net_secret_init();
-   hash[0] = (__force u32)saddr;
-   hash[1] = (__force u32)daddr;
-   hash[2] = (__force u32)dport ^ net_secret[14];
-   hash[3] = net_secret[15];
-
-   md5_transform(hash, net_secret);
-
-   return hash[0];
+   return seq_scale(siphash24((const u8 *), sizeof(combined), 
net_secret));
 }
 EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
 #endif
@@ -123,21 +119,22 @@