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    Subject[PATCH 5.13 055/113] ipv4: use siphash instead of Jenkins in fnhe_hashfun()
    Date
    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit 6457378fe796815c973f631a1904e147d6ee33b1 ]

    A group of security researchers brought to our attention
    the weakness of hash function used in fnhe_hashfun().

    Lets use siphash instead of Jenkins Hash, to considerably
    reduce security risks.

    Also remove the inline keyword, this really is distracting.

    Fixes: d546c621542d ("ipv4: harden fnhe_hashfun()")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Reported-by: Keyu Man <kman001@ucr.edu>
    Cc: Willy Tarreau <w@1wt.eu>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/ipv4/route.c | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    diff --git a/net/ipv4/route.c b/net/ipv4/route.c
    index 78d1e5afc452..d8811e1fbd6c 100644
    --- a/net/ipv4/route.c
    +++ b/net/ipv4/route.c
    @@ -600,14 +600,14 @@ static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
    return oldest;
    }

    -static inline u32 fnhe_hashfun(__be32 daddr)
    +static u32 fnhe_hashfun(__be32 daddr)
    {
    - static u32 fnhe_hashrnd __read_mostly;
    - u32 hval;
    + static siphash_key_t fnhe_hash_key __read_mostly;
    + u64 hval;

    - net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
    - hval = jhash_1word((__force u32)daddr, fnhe_hashrnd);
    - return hash_32(hval, FNHE_HASH_SHIFT);
    + net_get_random_once(&fnhe_hash_key, sizeof(fnhe_hash_key));
    + hval = siphash_1u32((__force u32)daddr, &fnhe_hash_key);
    + return hash_64(hval, FNHE_HASH_SHIFT);
    }

    static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
    --
    2.30.2


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