When asyncronous crypto algorithms are used, there might be many
packets that passed the xfrm replay check, but the replay advance
function is not called yet for these packets. So the replay check
function would accept a replay of all of these packets. Also the
system might crash if there are more packets in async processing
than the size of the anti replay window, because the replay advance
function would try to update the replay window beyond the bounds.
This pach adds a second replay check after resuming from the async
processing to fix these issues.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
net/xfrm/xfrm_input.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
@@ -212,6 +212,11 @@ resume:/* only the first xfrm gets the encap type */encap_type=0;+if(async&&x->repl->check(x,skb,seq)){+XFRM_INC_STATS(net,LINUX_MIB_XFRMINSTATESEQERROR);+gotodrop_unlock;+}+x->repl->advance(x,seq);x->curlft.bytes+=skb->len;
From: Herbert Xu <herbert@gondor.apana.org.au> Date: 2011-09-21 11:22:05
On Wed, Sep 21, 2011 at 11:38:58AM +0200, Steffen Klassert wrote:
When asyncronous crypto algorithms are used, there might be many
packets that passed the xfrm replay check, but the replay advance
function is not called yet for these packets. So the replay check
function would accept a replay of all of these packets. Also the
system might crash if there are more packets in async processing
than the size of the anti replay window, because the replay advance
function would try to update the replay window beyond the bounds.
This pach adds a second replay check after resuming from the async
processing to fix these issues.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
On Wed, Sep 21, 2011 at 09:21:58PM +1000, Herbert Xu wrote:
On Wed, Sep 21, 2011 at 11:38:58AM +0200, Steffen Klassert wrote:
quoted
When asyncronous crypto algorithms are used, there might be many
packets that passed the xfrm replay check, but the replay advance
function is not called yet for these packets. So the replay check
function would accept a replay of all of these packets. Also the
system might crash if there are more packets in async processing
than the size of the anti replay window, because the replay advance
function would try to update the replay window beyond the bounds.
This pach adds a second replay check after resuming from the async
processing to fix these issues.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Actually why does this matter? For a single SA, the processing
in xfrm_input should be completely synchronous, even when you're
using asynchronous algorithms.
Well, I've got pretty reproduceable crashes when the sender of
the IPsec packets introduces reorder, that's why I noticed this.
The problem is, that the replay check function is called before
the asynchronous crypto processing and the replay advance function
is called after resume from the asynchronous processing. So
we can submit multiple packets to the crypto layer without
updating the replay window. This means that the replay check
function accepts packets that should have been dropped, because
they are reordered and more than 'replay window size' packets
to late. This leads to a crash as we try to update the replay
window beyond the allocated bounds.
From: Herbert Xu <herbert@gondor.apana.org.au> Date: 2011-09-21 12:24:47
On Wed, Sep 21, 2011 at 01:57:27PM +0200, Steffen Klassert wrote:
Well, I've got pretty reproduceable crashes when the sender of
the IPsec packets introduces reorder, that's why I noticed this.
The problem is, that the replay check function is called before
the asynchronous crypto processing and the replay advance function
is called after resume from the asynchronous processing. So
we can submit multiple packets to the crypto layer without
updating the replay window. This means that the replay check
function accepts packets that should have been dropped, because
they are reordered and more than 'replay window size' packets
to late. This leads to a crash as we try to update the replay
window beyond the allocated bounds.
On Wed, Sep 21, 2011 at 01:57:27PM +0200, Steffen Klassert wrote:
quoted
Well, I've got pretty reproduceable crashes when the sender of
the IPsec packets introduces reorder, that's why I noticed this.
The problem is, that the replay check function is called before
the asynchronous crypto processing and the replay advance function
is called after resume from the asynchronous processing. So
we can submit multiple packets to the crypto layer without
updating the replay window. This means that the replay check
function accepts packets that should have been dropped, because
they are reordered and more than 'replay window size' packets
to late. This leads to a crash as we try to update the replay
window beyond the allocated bounds.
OK I see what you mean now.
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>