net: Compute protocol sequence numbers and fragment IDs using MD5.

Computers have become a lot faster since we compromised on the
partial MD4 hash which we use currently for performance reasons.

MD5 is a much safer choice, and is inline with both RFC1948 and
other ISS generators (OpenBSD, Solaris, etc.)

Furthermore, only having 24-bits of the sequence number be truly
unpredictable is a very serious limitation.  So the periodic
regeneration and 8-bit counter have been removed.  We compute and
use a full 32-bit sequence number.

For ipv6, DCCP was found to use a 32-bit truncated initial sequence
number (it needs 43-bits) and that is fixed here as well.

Reported-by: Dan Kaminsky <dan@doxpara.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 7 deletions

diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 8dc4348774a5..b74f76117dcf 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -29,6 +29,7 @@
 #include <net/transp_v6.h>
 #include <net/ip6_checksum.h>
 #include <net/xfrm.h>
+#include <net/secure_seq.h>
 
 #include "dccp.h"
 #include "ipv6.h"
@@ -69,13 +70,7 @@ static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb)
         dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr);
 }
 
-static inline __u32 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
-                                                  __be16 sport, __be16 dport   )
-{
-        return secure_tcpv6_sequence_number(saddr, daddr, sport, dport);
-}
-
-static inline __u32 dccp_v6_init_sequence(struct sk_buff *skb)
+static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)
 {
         return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
                                              ipv6_hdr(skb)->saddr.s6_addr32,