[kernel/f20] CVE-XXXX-XXX DoS due to routing packets to too many different dsts/too fast (rhbz 1183744 1188347)
Josh Boyer
jwboyer at fedoraproject.org
Mon Feb 2 19:32:34 UTC 2015
commit 586c0b53dacff31a4a5cd0702a267f033e0e833d
Author: Josh Boyer <jwboyer at fedoraproject.org>
Date: Mon Feb 2 14:02:40 2015 -0500
CVE-XXXX-XXX DoS due to routing packets to too many different dsts/too fast (rhbz 1183744 1188347)
...-cache-dst_entries-which-would-cause-a-re.patch | 99 ++++++++++++++++++++
kernel.spec | 9 ++
2 files changed, 108 insertions(+), 0 deletions(-)
---
diff --git a/ipv4-try-to-cache-dst_entries-which-would-cause-a-re.patch b/ipv4-try-to-cache-dst_entries-which-would-cause-a-re.patch
new file mode 100644
index 0000000..fbafb53
--- /dev/null
+++ b/ipv4-try-to-cache-dst_entries-which-would-cause-a-re.patch
@@ -0,0 +1,99 @@
+From: Hannes Frederic Sowa <hannes at stressinduktion.org>
+Date: Fri, 23 Jan 2015 12:01:26 +0100
+Subject: [PATCH] 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 at ssi.bg>
+Signed-off-by: Marcelo Leitner <mleitner at redhat.com>
+Signed-off-by: Florian Westphal <fw at strlen.de>
+Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
+Signed-off-by: Julian Anastasov <ja at ssi.bg>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ include/net/ip.h | 11 ++++++-----
+ net/ipv4/ip_forward.c | 3 ++-
+ net/ipv4/route.c | 9 +++++----
+ 3 files changed, 13 insertions(+), 10 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;
+ };
+diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
+index 3a83ce5efa80..787b3c294ce6 100644
+--- a/net/ipv4/ip_forward.c
++++ b/net/ipv4/ip_forward.c
+@@ -129,7 +129,8 @@ int ip_forward(struct sk_buff *skb)
+ * We now generate an ICMP HOST REDIRECT giving the route
+ * we calculated.
+ */
+- if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr && !skb_sec_path(skb))
++ if (IPCB(skb)->flags & IPSKB_DOREDIRECT && !opt->srr &&
++ !skb_sec_path(skb))
+ ip_rt_send_redirect(skb);
+
+ skb->priority = rt_tos2priority(iph->tos);
+diff --git a/net/ipv4/route.c b/net/ipv4/route.c
+index 6a2155b02602..d58dd0ec3e53 100644
+--- a/net/ipv4/route.c
++++ b/net/ipv4/route.c
+@@ -1554,11 +1554,10 @@ static int __mkroute_input(struct sk_buff *skb,
+
+ do_cache = res->fi && !itag;
+ if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
++ skb->protocol == htons(ETH_P_IP) &&
+ (IN_DEV_SHARED_MEDIA(out_dev) ||
+- inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res)))) {
+- flags |= RTCF_DOREDIRECT;
+- do_cache = false;
+- }
++ inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
++ IPCB(skb)->flags |= IPSKB_DOREDIRECT;
+
+ if (skb->protocol != htons(ETH_P_IP)) {
+ /* Not IP (i.e. ARP). Do not create route, if it is
+@@ -2303,6 +2302,8 @@ static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
+ r->rtm_flags = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
+ if (rt->rt_flags & RTCF_NOTIFY)
+ r->rtm_flags |= RTM_F_NOTIFY;
++ if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
++ r->rtm_flags |= RTCF_DOREDIRECT;
+
+ if (nla_put_be32(skb, RTA_DST, dst))
+ goto nla_put_failure;
+--
+2.1.0
+
diff --git a/kernel.spec b/kernel.spec
index a09d517..2441bed 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -750,6 +750,9 @@ Patch30000: kernel-arm64.patch
# Fix for big-endian arches, already upstream
Patch30001: mpssd-x86-only.patch
+# rhbz 1183744 1188347
+Patch30002: ipv4-try-to-cache-dst_entries-which-would-cause-a-re.patch
+
# END OF PATCH DEFINITIONS
%endif
@@ -1463,6 +1466,9 @@ ApplyPatch acpi-video-Add-disable_native_backlight-quirk-for-Sa.patch
# Fix for big-endian arches, already upstream
ApplyPatch mpssd-x86-only.patch
+# rhbz 1183744 1188347
+ApplyPatch ipv4-try-to-cache-dst_entries-which-would-cause-a-re.patch
+
%if 0%{?aarch64patches}
ApplyPatch kernel-arm64.patch
%ifnarch aarch64 # this is stupid, but i want to notice before secondary koji does.
@@ -2281,6 +2287,9 @@ fi
# ||----w |
# || ||
%changelog
+* Mon Feb 02 2015 Josh Boyer <jwboyer at fedoraproject.org>
+- CVE-XXXX-XXX DoS due to routing packets to too many different dsts/too fast (rhbz 1183744 1188347)
+
* Fri Jan 30 2015 Justin M. Forbes <jforbes at fedoraproject.org> - 3.18.5-100
- Linux v3.18.5
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