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https://github.com/Divested-Mobile/DivestOS-Build.git
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101 lines
3.6 KiB
Diff
101 lines
3.6 KiB
Diff
From df4d92549f23e1c037e83323aff58a21b3de7fe0 Mon Sep 17 00:00:00 2001
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From: Hannes Frederic Sowa <hannes@stressinduktion.org>
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Date: Fri, 23 Jan 2015 12:01:26 +0100
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Subject: ipv4: try to cache dst_entries which would cause a redirect
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Not caching dst_entries which cause redirects could be exploited by hosts
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on the same subnet, causing a severe DoS attack. This effect aggravated
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since commit f88649721268999 ("ipv4: fix dst race in sk_dst_get()").
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Lookups causing redirects will be allocated with DST_NOCACHE set which
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will force dst_release to free them via RCU. Unfortunately waiting for
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RCU grace period just takes too long, we can end up with >1M dst_entries
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waiting to be released and the system will run OOM. rcuos threads cannot
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catch up under high softirq load.
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Attaching the flag to emit a redirect later on to the specific skb allows
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us to cache those dst_entries thus reducing the pressure on allocation
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and deallocation.
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This issue was discovered by Marcelo Leitner.
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Cc: Julian Anastasov <ja@ssi.bg>
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Signed-off-by: Marcelo Leitner <mleitner@redhat.com>
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Signed-off-by: Florian Westphal <fw@strlen.de>
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Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
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Signed-off-by: Julian Anastasov <ja@ssi.bg>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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include/net/ip.h | 11 ++++++-----
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net/ipv4/ip_forward.c | 3 ++-
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net/ipv4/route.c | 9 +++++----
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3 files changed, 13 insertions(+), 10 deletions(-)
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diff --git a/include/net/ip.h b/include/net/ip.h
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index 0bb6207..f7cbd70 100644
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--- a/include/net/ip.h
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+++ b/include/net/ip.h
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@@ -39,11 +39,12 @@ struct inet_skb_parm {
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struct ip_options opt; /* Compiled IP options */
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unsigned char flags;
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-#define IPSKB_FORWARDED 1
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-#define IPSKB_XFRM_TUNNEL_SIZE 2
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-#define IPSKB_XFRM_TRANSFORMED 4
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-#define IPSKB_FRAG_COMPLETE 8
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-#define IPSKB_REROUTED 16
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+#define IPSKB_FORWARDED BIT(0)
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+#define IPSKB_XFRM_TUNNEL_SIZE BIT(1)
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+#define IPSKB_XFRM_TRANSFORMED BIT(2)
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+#define IPSKB_FRAG_COMPLETE BIT(3)
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+#define IPSKB_REROUTED BIT(4)
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+#define IPSKB_DOREDIRECT BIT(5)
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u16 frag_max_size;
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};
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diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
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index 3a83ce5..787b3c2 100644
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--- a/net/ipv4/ip_forward.c
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+++ b/net/ipv4/ip_forward.c
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@@ -129,7 +129,8 @@ int ip_forward(struct sk_buff *skb)
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* We now generate an ICMP HOST REDIRECT giving the route
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* we calculated.
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*/
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- if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb))
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+ if (IPCB(skb)->flags & IPSKB_DOREDIRECT && !opt->srr &&
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+ !skb_sec_path(skb))
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ip_rt_send_redirect(skb);
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skb->priority = rt_tos2priority(iph->tos);
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diff --git a/net/ipv4/route.c b/net/ipv4/route.c
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index 6a2155b..d58dd0e 100644
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--- a/net/ipv4/route.c
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+++ b/net/ipv4/route.c
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@@ -1554,11 +1554,10 @@ static int __mkroute_input(struct sk_buff *skb,
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do_cache = res->fi && !itag;
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if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
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+ skb->protocol == htons(ETH_P_IP) &&
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(IN_DEV_SHARED_MEDIA(out_dev) ||
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- inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res)))) {
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- flags |= RTCF_DOREDIRECT;
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- do_cache = false;
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- }
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+ inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
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+ IPCB(skb)->flags |= IPSKB_DOREDIRECT;
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if (skb->protocol != htons(ETH_P_IP)) {
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/* Not IP (i.e. ARP). Do not create route, if it is
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@@ -2303,6 +2302,8 @@ static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
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r->rtm_flags = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
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if (rt->rt_flags & RTCF_NOTIFY)
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r->rtm_flags |= RTM_F_NOTIFY;
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+ if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
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+ r->rtm_flags |= RTCF_DOREDIRECT;
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if (nla_put_be32(skb, RTA_DST, dst))
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goto nla_put_failure;
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--
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cgit v1.1
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