From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Jones Subject: [PATCH net-next v4] ipv6: Allocate unique metrics for icmp6 packets to prevent tainting dst metrics Date: Sun, 18 Mar 2012 01:43:39 +0800 Message-ID: <4F64CD4B.4070203@network-box.com> References: <4F620DC5.7080607@network-box.com> <20120316.230245.1004014834159539357.davem@davemloft.net> <4F64B203.40307@network-box.com> <1332002201.19406.25.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from network-box.com ([175.45.17.220]:35492 "EHLO network-box.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1756881Ab2CQRnm (ORCPT ); Sat, 17 Mar 2012 13:43:42 -0400 In-Reply-To: <1332002201.19406.25.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: The generation of an icmp6 packet, targeted to a specific desination address, will cause the shared metrics of the ip6_dst and inetpeer of that address to be tainted with the hoplimit value 255. All packets, icmp6 or otherwise, will have this hoplimit value, and if the destination is a router, not even advertisements specifying a new hoplimit value will have any effect due to the way ip6_dst_hoplimit works. By allocating a unique metrics array for the icmp6 packet, the shared metrics will not be tainted. A ip6_dst flag is added to indicate that the metrics for the dst don't belong to the peer, thus are not unique and should be freed when the dst is freed. Signed-off-by: Nick Jones --- v2: Forgot to handle destroy side, as pointed out by David Miller. Achieved by setting a flag on the dst to indicate its metrics are unique, thus should be destroyed along with the dst. v3: David Miller reminds that metrics pointer should be declared at function top. v4: Eric Dumazet suggest argument of dst_init_metrics change to from literal 0 to keyword 'false'. include/net/dst.h | 1 + net/ipv6/route.c | 13 +++++++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index 344c8dd..ee7a781 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -54,6 +54,7 @@ struct dst_entry { #define DST_NOCACHE 0x0010 #define DST_NOCOUNT 0x0020 #define DST_NOPEER 0x0040 +#define DST_NOPEERMETRICS 0x0080 short error; short obsolete; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 92be12b..d96ccc5 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -278,7 +278,7 @@ static void ip6_dst_destroy(struct dst_entry *dst) struct inet6_dev *idev = rt->rt6i_idev; struct inet_peer *peer = rt->rt6i_peer; - if (!(rt->dst.flags & DST_HOST)) + if (!(rt->dst.flags & DST_HOST) || (rt->dst.flags & DST_NOPEERMETRICS)) dst_destroy_metrics_generic(dst); if (idev) { @@ -1088,6 +1088,7 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct rt6_info *rt; struct inet6_dev *idev = in6_dev_get(dev); struct net *net = dev_net(dev); + u32 *metrics; if (unlikely(!idev)) return NULL; @@ -1110,13 +1111,21 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev, } } - rt->dst.flags |= DST_HOST; + rt->dst.flags |= (DST_HOST | DST_NOPEERMETRICS); rt->dst.output = ip6_output; dst_set_neighbour(&rt->dst, neigh); atomic_set(&rt->dst.__refcnt, 1); rt->rt6i_dst.addr = fl6->daddr; rt->rt6i_dst.plen = 128; rt->rt6i_idev = idev; + + metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC); + if (unlikely(!metrics)) { + in6_dev_put(idev); + dst_free(&rt->dst); + return ERR_CAST(-ENOMEM); + } + dst_init_metrics(&rt->dst, metrics, false); dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 255); spin_lock_bh(&icmp6_dst_lock); -- 1.7.1