| Message ID | 20110921093858.GW1808@secunet.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
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> 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. Cheers,
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: > > 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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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. OK I see what you mean now. Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Thanks!
From: Herbert Xu <herbert@gondor.hengli.com.au> Date: Wed, 21 Sep 2011 22:24:42 +1000 > 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. > > OK I see what you mean now. > > Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Applied, thanks everyone. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index a026b0e..54a0dc2 100644 --- a/net/xfrm/xfrm_input.c +++ b/net/xfrm/xfrm_input.c @@ -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); + goto drop_unlock; + } + x->repl->advance(x, seq); x->curlft.bytes += skb->len;
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(-)