linux-kernel - [PATCH 3.13.y-ckt 90/95] skbuff: Do not scrub skb mark within the same name space

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Message-Id: <1432753243-16151-91-git-send-email-kamal@canonical.com>
Date:	Wed, 27 May 2015 12:00:38 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 90/95] skbuff: Do not scrub skb mark within the same name space

3.13.11-ckt21 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@...dor.apana.org.au>

commit 213dd74aee765d4e5f3f4b9607fef0cf97faa2af upstream.

On Wed, Apr 15, 2015 at 05:41:26PM +0200, Nicolas Dichtel wrote:
> Le 15/04/2015 15:57, Herbert Xu a écrit :
> >On Wed, Apr 15, 2015 at 06:22:29PM +0800, Herbert Xu wrote:
> [snip]
> >Subject: skbuff: Do not scrub skb mark within the same name space
> >
> >The commit ea23192e8e577dfc51e0f4fc5ca113af334edff9 ("tunnels:
> Maybe add a Fixes tag?
> Fixes: ea23192e8e57 ("tunnels: harmonize cleanup done on skb on rx path")
>
> >harmonize cleanup done on skb on rx path") broke anyone trying to
> >use netfilter marking across IPv4 tunnels.  While most of the
> >fields that are cleared by skb_scrub_packet don't matter, the
> >netfilter mark must be preserved.
> >
> >This patch rearranges skb_scurb_packet to preserve the mark field.
> nit: s/scurb/scrub
>
> Else it's fine for me.

Sure.

PS I used the wrong email for James the first time around.  So
let me repeat the question here.  Should secmark be preserved
or cleared across tunnels within the same name space? In fact,
do our security models even support name spaces?

---8<---
The commit ea23192e8e577dfc51e0f4fc5ca113af334edff9 ("tunnels:
harmonize cleanup done on skb on rx path") broke anyone trying to
use netfilter marking across IPv4 tunnels.  While most of the
fields that are cleared by skb_scrub_packet don't matter, the
netfilter mark must be preserved.

This patch rearranges skb_scrub_packet to preserve the mark field.

Fixes: ea23192e8e57 ("tunnels: harmonize cleanup done on skb on rx path")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Acked-by: Thomas Graf <tgraf@...g.ch>
Signed-off-by: David S. Miller <davem@...emloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 net/core/skbuff.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1008034..a937b23 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3578,18 +3578,21 @@ EXPORT_SYMBOL(skb_try_coalesce);
  */
 void skb_scrub_packet(struct sk_buff *skb, bool xnet)
 {
-	if (xnet)
-		skb_orphan(skb);
 	skb->tstamp.tv64 = 0;
 	skb->pkt_type = PACKET_HOST;
 	skb->skb_iif = 0;
 	skb->local_df = 0;
 	skb_dst_drop(skb);
-	skb->mark = 0;
 	skb_init_secmark(skb);
 	secpath_reset(skb);
 	nf_reset(skb);
 	nf_reset_trace(skb);
+
+	if (!xnet)
+		return;
+
+	skb_orphan(skb);
+	skb->mark = 0;
 }
 EXPORT_SYMBOL_GPL(skb_scrub_packet);
 
-- 
1.9.1

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