On Tue, 19 May 2020 13:21:56 -0400 Pooja Trivedi wrote: > On Mon, May 18, 2020 at 6:50 PM Jakub Kicinski <kuba@xxxxxxxxxx> wrote: > > On Sun, 17 May 2020 16:26:36 +0000 Pooja Trivedi wrote: > > > In pure sw ktls(AES-NI), -EAGAIN from tcp layer (do_tcp_sendpages for > > > encrypted record) gets treated as error, subtracts the offset, and > > > returns to application. Because of this, application sends data from > > > subtracted offset, which leads to data integrity issue. Since record is > > > already encrypted, ktls module marks it as partially sent and pushes the > > > packet to tcp layer in the following iterations (either from bottom half > > > or when pushing next chunk). So returning success in case of EAGAIN > > > will fix the issue. > > > > > > Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption") > > > Signed-off-by: Pooja Trivedi <pooja.trivedi@xxxxxxxxxxxxx> > > > Reviewed-by: Mallesham Jatharkonda <mallesham.jatharkonda@xxxxxxxxxxxxxxxxxx> > > > Reviewed-by: Josh Tway <josh.tway@xxxxxxxxxxxxx> > > > > This looks reasonable, I think. Next time user space calls if no new > > buffer space was made available it will get a -EAGAIN, right? > > Yes, this fix should only affect encrypted record. Plain text calls from > user space should be unaffected. AFAICS if TCP layer is full next call from user space should hit sk_stream_wait_memory() immediately and if it has MSG_DONTWAIT set exit with EAGAIN. Which I believe to be correct behavior. > > Two questions - is there any particular application or use case that > > runs into this? > > We are running into this case when we hit our kTLS-enabled homegrown > webserver with a 'pipeline' test tool, also homegrown. The issue basically > happens whenever the send buffer on the server gets full and TCP layer > returns EAGAIN when attempting to TX the encrypted record. In fact, we > are also able to reproduce the issue by using a simple wget with a large > file, if/when sndbuf fills up. I see just a coincidence, then, no worries. > > Seems a bit surprising to see a patch from Vadim and > > you guys come at the same time. > > Not familiar with Vadim or her/his patch. Could you please point me to it? http://patchwork.ozlabs.org/project/netdev/patch/20200517014451.954F05026DE@xxxxxxxx/ > > Could you also add test for this bug? > > In tools/testing/selftests/net/tls.c > > > > Sure, yes. Let me look into this. Thanks!