ipv6: make fragment identifications less predictable

IPv6 fragment identification generation is way beyond what we use for
IPv4 : It uses a single generator. Its not scalable and allows DOS
attacks.

Now inetpeer is IPv6 aware, we can use it to provide a more secure and
scalable frag ident generator (per destination, instead of system wide)

This patch :
1) defines a new secure_ipv6_id() helper
2) extends inet_getid() to provide 32bit results
3) extends ipv6_select_ident() with a new dest parameter

Reported-by: Fernando Gont <fernando@gont.com.ar>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/random.h b/include/linux/random.h
index fb7ab9de5f36..ce29a040c8dc 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -58,6 +58,7 @@ extern void get_random_bytes(void *buf, int nbytes);
 void generate_random_uuid(unsigned char uuid_out[16]);
 
 extern __u32 secure_ip_id(__be32 daddr);
+extern __u32 secure_ipv6_id(const __be32 daddr[4]);
 extern u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
 extern u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
                                       __be16 dport);