diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-03-27 12:40:33 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-09 09:18:10 +0200 |
| commit | e10789acbe6a76b304f45cbc8bb77a926ae4f201 (patch) | |
| tree | 65f071401201bf2c48c4fa9f2029994b7f1efeac /net/ipv4 | |
| parent | 8cb1239889087368a792c655de99529eec219bfc (diff) | |
inet: switch IP ID generator to siphash
[ Upstream commit df453700e8d81b1bdafdf684365ee2b9431fb702 ]
According to Amit Klein and Benny Pinkas, IP ID generation is too weak
and might be used by attackers.
Even with recent net_hash_mix() fix (netns: provide pure entropy for net_hash_mix())
having 64bit key and Jenkins hash is risky.
It is time to switch to siphash and its 128bit keys.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/route.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6a7e187dd0a9..3b72990a8bb9 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -517,15 +517,17 @@ EXPORT_SYMBOL(ip_idents_reserve); void __ip_select_ident(struct net *net, struct iphdr *iph, int segs) { - static u32 ip_idents_hashrnd __read_mostly; u32 hash, id; - net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd)); + /* Note the following code is not safe, but this is okay. */ + if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key))) + get_random_bytes(&net->ipv4.ip_id_key, + sizeof(net->ipv4.ip_id_key)); - hash = jhash_3words((__force u32)iph->daddr, + hash = siphash_3u32((__force u32)iph->daddr, (__force u32)iph->saddr, - iph->protocol ^ net_hash_mix(net), - ip_idents_hashrnd); + iph->protocol, + &net->ipv4.ip_id_key); id = ip_idents_reserve(hash, segs); iph->id = htons(id); } |