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authorHannes Frederic Sowa <hannes@stressinduktion.org>2015-01-23 12:01:26 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-02-26 17:48:48 -0800
commit8c6dafeba6f8d1435f05e39142b50bc605f7a91c (patch)
treeff6af5aeeb861d86d53da66b6c49ac669c483c7d /include
parent727ab4c06af65c1b2313c95dfcd8827318d5a438 (diff)
ipv4: try to cache dst_entries which would cause a redirect
[ Upstream commit df4d92549f23e1c037e83323aff58a21b3de7fe0 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/net/ip.h11
1 files changed, 6 insertions, 5 deletions
diff --git a/include/net/ip.h b/include/net/ip.h
index 8695359982d1..e47ad4c01608 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -37,11 +37,12 @@ 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;
};