Messages in this thread | | | Date | Mon, 19 Jun 2023 17:59:10 +0100 | Subject | Re: [PATCH v7 04/22] net/tcp: Prevent TCP-MD5 with TCP-AO being set | From | Dmitry Safonov <> |
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On 6/19/23 17:41, Dmitry Safonov wrote: > On 6/19/23 17:31, Dmitry Safonov wrote: >> Hi David, >> >> On 6/18/23 18:50, David Ahern wrote: >>> On 6/14/23 4:09 PM, Dmitry Safonov wrote: >>>> Be as conservative as possible: if there is TCP-MD5 key for a given peer >>>> regardless of L3 interface - don't allow setting TCP-AO key for the same >>>> peer. According to RFC5925, TCP-AO is supposed to replace TCP-MD5 and >>>> there can't be any switch between both on any connected tuple. >>>> Later it can be relaxed, if there's a use, but in the beginning restrict >>>> any intersection. >>>> >>>> Note: it's still should be possible to set both TCP-MD5 and TCP-AO keys >>>> on a listening socket for *different* peers. >>> >>> Does the testsuite cover use of both MD5 and AO for a single listening >>> socket with different peers and then other tests covering attempts to >>> use both for a same peer? >> >> Thanks for the question, I have written the following tests for >> AO/MD5/unsigned listening socket [1]: >> >> 1. Listener with TCP-AO key, which has addr = INADDR_ANY >> 2. Listener with TCP-MD5 key, which has tcpm_addr = INADDR_ANY >> 3. Listener without any key >> >> Then there's AO_REQUIRED thing, which BGP folks asked to introduce, >> which is (7.3) from RFC5925, an option that is per-ao_info, which makes >> such socket accepting only TCP-AO enabled segments. >> >> So, 4. Listener with TCP-AO, AO_REQUIRED flag. >> >> And then, going to non-INADDR_ANY: >> 5. Listener with TCP-AO and TCP-MD5 keys for different peers. >> >> Here again, for each of AO/MD5/unsigned methods, attempt to connect: >> 6. outside of both key peers >> 7. inside correct key: i.e. TCP-MD5 client to TCP-MD5 matching key >> 8. to a wrong key: i.e. TCP-AO client to TCP-MD5 matching key >> >> And another type of checks are the ones expecting *setsockopt()* to fail: >> 9. Adding TCP-AO key that matches the same peer as TCP-MD5 key >> 10. The reverse situation >> 11. Adding TCP-MD5 key to AO_REQUIRED socket >> 12. Setting AO_REQUIRED on a socket with TCP-MD5 key >> 13. Adding TCP-AO key on already established connection without any key > > Oh, yeah, forgot to mention, there are another 2 tests for TCP_CLOSE > socket (just a new one), that has both TCP-AO and TCP-MD5 keys and tries > to call connect(). In discussion with the team, it seems really > unexpected situation and better to force userspace to remove either AO > or MD5 key before calling connect(). Those from the output in [1] are: > >> ok 39 AO+MD5 server: client with both [TCP-MD5] and TCP-AO keys: > connect() was prevented >> ok 40 AO+MD5 server: client with both TCP-MD5 and [TCP-AO] keys: > connect() was prevented
And while starring at the selftest results, I noticed in the output sample a copy-n-paste typo for VRFs, this: > ok 60 VRF: TCP-AO key (l3index=0) + TCP-MD5 key (no l3index) > ok 61 VRF: TCP-MD5 key (no l3index) + TCP-AO key (l3index=0)
Should be read as > ok 60 VRF: TCP-AO key (l3index=0) + TCP-MD5 key (l3index=N) > ok 61 VRF: TCP-MD5 key (l3index=N) + TCP-AO key (l3index=0)
(those checks are corresponding to the table in VRF-support commit [2])
>> And then another bunch of tests that check TCP-AO/TCP-MD5/unsigned >> interaction in non/default VRFs. >> I think the output of selftest [1] is more-or-less self-descriptive, >> correct me if I could improve that. >> >> [1] >> https://github.com/0x7f454c46/linux/commit/d7b321f2b5a481e5ff0e80e2e0b3503b1ddb9817
[2] https://lore.kernel.org/all/20230614230947.3954084-22-dima@arista.com/T/#u
Thanks, Dmitry
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