Commit 4daf4dc2 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
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ipv6: switch inet6_acaddr_hash() to less predictable hash 



commit 2384d025 ("net/ipv6: Add anycast addresses to a global hashtable")
added inet6_acaddr_hash(), using ipv6_addr_hash() and net_hash_mix()
to get hash spreading for typical users.

However ipv6_addr_hash() is highly predictable and a malicious user
could abuse a specific hash bucket.

Switch to __ipv6_addr_jhash(). We could use a dedicated
secret, or reuse net_hash_mix() as I did in this patch.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20241008121307.800040-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4a0ec2aa

net/ipv6/anycast.c

+3 −2
Original line number Diff line number Diff line
@@ -49,9 +49,10 @@ static DEFINE_SPINLOCK(acaddr_hash_lock); 


static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);



static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr)

static u32 inet6_acaddr_hash(const struct net *net,

			     const struct in6_addr *addr)

{

	u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);

	u32 val = __ipv6_addr_jhash(addr, net_hash_mix(net));



	return hash_32(val, IN6_ADDR_HSIZE_SHIFT);

}