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author | Hannes Frederic Sowa <hannes@stressinduktion.org> | 2015-01-23 12:01:26 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2015-01-26 17:28:27 -0800 |
commit | df4d92549f23e1c037e83323aff58a21b3de7fe0 (patch) | |
tree | cb82536dd48281496b6652b628266cdcacffb91d /include | |
parent | 412d2907c41531b60c7ea1f38cfe1116daf2a229 (diff) | |
download | linux-df4d92549f23e1c037e83323aff58a21b3de7fe0.tar.gz |
ipv4: try to cache dst_entries which would cause a redirect
Not caching dst_entries which cause redirects could be exploited by hosts on the same subnet, causing a severe DoS attack. This effect aggravated since commit f88649721268999 ("ipv4: fix dst race in sk_dst_get()"). Lookups causing redirects will be allocated with DST_NOCACHE set which will force dst_release to free them via RCU. Unfortunately waiting for RCU grace period just takes too long, we can end up with >1M dst_entries waiting to be released and the system will run OOM. rcuos threads cannot catch up under high softirq load. Attaching the flag to emit a redirect later on to the specific skb allows us to cache those dst_entries thus reducing the pressure on allocation and deallocation. This issue was discovered by Marcelo Leitner. Cc: Julian Anastasov <ja@ssi.bg> Signed-off-by: Marcelo Leitner <mleitner@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r-- | include/net/ip.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/include/net/ip.h b/include/net/ip.h index 0bb620702929..f7cbd703d15d 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -39,11 +39,12 @@ struct inet_skb_parm { struct ip_options opt; /* Compiled IP options */ unsigned char flags; -#define IPSKB_FORWARDED 1 -#define IPSKB_XFRM_TUNNEL_SIZE 2 -#define IPSKB_XFRM_TRANSFORMED 4 -#define IPSKB_FRAG_COMPLETE 8 -#define IPSKB_REROUTED 16 +#define IPSKB_FORWARDED BIT(0) +#define IPSKB_XFRM_TUNNEL_SIZE BIT(1) +#define IPSKB_XFRM_TRANSFORMED BIT(2) +#define IPSKB_FRAG_COMPLETE BIT(3) +#define IPSKB_REROUTED BIT(4) +#define IPSKB_DOREDIRECT BIT(5) u16 frag_max_size; }; |