Messages in this thread | | | Date | Fri, 24 Feb 2023 22:48:57 +0100 | From | Sabrina Dubroca <> | Subject | Re: [PATCH] net: tls: fix possible race condition between do_tls_getsockopt_conf() and do_tls_setsockopt_conf() |
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2023-02-24, 13:06:25 -0800, Jakub Kicinski wrote: > On Fri, 24 Feb 2023 21:22:43 +0100 Sabrina Dubroca wrote: > > > Right, the bug and the fix seem completely bogus. > > > Please make sure the bugs are real and the fixes you sent actually > > > fix them. > > > > I suggested a change of locking in do_tls_getsockopt_conf this > > morning [1]. The issue reported last seemed valid, but this patch is not > > at all what I had in mind. > > [1] https://lore.kernel.org/all/Y/ht6gQL+u6fj3dG@hog/ > > Ack, I read the messages out of order, sorry. > > > do_tls_setsockopt_conf fills crypto_info immediately from what > > userspace gives us (and clears it on exit in case of failure), which > > getsockopt could see since it's not locking the socket when it checks > > TLS_CRYPTO_INFO_READY. So getsockopt would progress up to the point it > > finally locks the socket, but if setsockopt failed, we could have > > cleared TLS_CRYPTO_INFO_READY and freed iv/rec_seq. > > Makes sense. We should just take the socket lock around all of > do_tls_getsockopt(), then?
That would make things simple and consistent. My idea was just taking the existing lock_sock in do_tls_getsockopt_conf out of the switch and put it just above TLS_CRYPTO_INFO_READY.
While we're at it, should we move the
ctx->prot_info.version != TLS_1_3_VERSION
check in do_tls_setsockopt_no_pad under lock_sock? I don't think that can do anything wrong (we'd have to get past this check just before a failing setsockopt clears crypto_info, and even then we're just reading a bit from the context), it just looks a bit strange. Or just lock the socket around all of do_tls_setsockopt_no_pad, like the other options we have.
-- Sabrina
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