From 4daf4dc275f1aa3b9629334c4185d62b7bdff1c4 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 8 Oct 2024 12:13:07 +0000 Subject: [PATCH] ipv6: switch inet6_acaddr_hash() to less predictable hash commit 2384d02520ff ("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: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20241008121307.800040-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv6/anycast.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c index 0627c4c18d1a..562cace50ca9 100644 --- a/net/ipv6/anycast.c +++ b/net/ipv6/anycast.c @@ -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); }