From 3f439c231a035bab056a5e20b1fd16f4c4c483c1 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 28 Oct 2021 20:56:30 +0300 Subject: [PATCH] ipv6: use siphash in rt6_exception_hash() commit 4785305c05b25a242e5314cc821f54ade4c18810 upstream. A group of security researchers brought to our attention the weakness of hash function used in rt6_exception_hash() Lets use siphash instead of Jenkins Hash, to considerably reduce security risks. Following patch deals with IPv4. Fixes: 35732d01fe31 ("ipv6: introduce a hash table to store dst cache") Signed-off-by: Eric Dumazet Reported-by: Keyu Man Cc: Wei Wang Cc: Martin KaFai Lau Acked-by: Wei Wang Signed-off-by: David S. Miller [OP: adjusted context for 5.4 stable] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- net/ipv6/route.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 3fb259c20546..daa876c6ae8d 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include #include @@ -1502,17 +1503,24 @@ static void rt6_exception_remove_oldest(struct rt6_exception_bucket *bucket) static u32 rt6_exception_hash(const struct in6_addr *dst, const struct in6_addr *src) { - static u32 seed __read_mostly; - u32 val; + static siphash_key_t rt6_exception_key __read_mostly; + struct { + struct in6_addr dst; + struct in6_addr src; + } __aligned(SIPHASH_ALIGNMENT) combined = { + .dst = *dst, + }; + u64 val; - net_get_random_once(&seed, sizeof(seed)); - val = jhash(dst, sizeof(*dst), seed); + net_get_random_once(&rt6_exception_key, sizeof(rt6_exception_key)); #ifdef CONFIG_IPV6_SUBTREES if (src) - val = jhash(src, sizeof(*src), val); + combined.src = *src; #endif - return hash_32(val, FIB6_EXCEPTION_BUCKET_SIZE_SHIFT); + val = siphash(&combined, sizeof(combined), &rt6_exception_key); + + return hash_64(val, FIB6_EXCEPTION_BUCKET_SIZE_SHIFT); } /* Helper function to find the cached rt in the hash table