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Thu, 19 Nov 2020 23:13:26 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: svn commit: r367530 - in head/sys/netinet: . tcp_stacks From: John Baldwin To: Michael Tuexen , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <202011092149.0A9Lnfmh069050@repo.freebsd.org> <9fd00098-0ce9-627e-0163-7ede5aa18d6f@FreeBSD.org> Autocrypt: addr=jhb@FreeBSD.org; keydata= mQGiBETQ+XcRBADMFybiq69u+fJRy/0wzqTNS8jFfWaBTs5/OfcV7wWezVmf9sgwn8TW0Dk0 c9MBl0pz+H01dA2ZSGZ5fXlmFIsee1WEzqeJzpiwd/pejPgSzXB9ijbLHZ2/E0jhGBcVy5Yo /Tw5+U/+laeYKu2xb0XPvM0zMNls1ah5OnP9a6Ql6wCgupaoMySb7DXm2LHD1Z9jTsHcAQMD /1jzh2BoHriy/Q2s4KzzjVp/mQO5DSm2z14BvbQRcXU48oAosHA1u3Wrov6LfPY+0U1tG47X 1BGfnQH+rNAaH0livoSBQ0IPI/8WfIW7ub4qV6HYwWKVqkDkqwcpmGNDbz3gfaDht6nsie5Z pcuCcul4M9CW7Md6zzyvktjnbz61BADGDCopfZC4of0Z3Ka0u8Wik6UJOuqShBt1WcFS8ya1 oB4rc4tXfSHyMF63aPUBMxHR5DXeH+EO2edoSwViDMqWk1jTnYza51rbGY+pebLQOVOxAY7k do5Ordl3wklBPMVEPWoZ61SdbcjhHVwaC5zfiskcxj5wwXd2E9qYlBqRg7QeSm9obiBCYWxk d2luIDxqaGJARnJlZUJTRC5vcmc+iGAEExECACAFAkTQ+awCGwMGCwkIBwMCBBUCCAMEFgID AQIeAQIXgAAKCRBy3lIGd+N/BI6RAJ9S97fvbME+3hxzE3JUyUZ6vTewDACdE1stFuSfqMvM jomvZdYxIYyTUpC5Ag0ERND5ghAIAPwsO0B7BL+bz8sLlLoQktGxXwXQfS5cInvL17Dsgnr3 1AKa94j9EnXQyPEj7u0d+LmEe6CGEGDh1OcGFTMVrof2ZzkSy4+FkZwMKJpTiqeaShMh+Goj XlwIMDxyADYvBIg3eN5YdFKaPQpfgSqhT+7El7w+wSZZD8pPQuLAnie5iz9C8iKy4/cMSOrH YUK/tO+Nhw8Jjlw94Ik0T80iEhI2t+XBVjwdfjbq3HrJ0ehqdBwukyeJRYKmbn298KOFQVHO EVbHA4rF/37jzaMadK43FgJ0SAhPPF5l4l89z5oPu0b/+5e2inA3b8J3iGZxywjM+Csq1tqz hltEc7Q+E08AAwUIAL+15XH8bPbjNJdVyg2CMl10JNW2wWg2Q6qdljeaRqeR6zFus7EZTwtX sNzs5bP8y51PSUDJbeiy2RNCNKWFMndM22TZnk3GNG45nQd4OwYK0RZVrikalmJY5Q6m7Z16 4yrZgIXFdKj2t8F+x613/SJW1lIr9/bDp4U9tw0V1g3l2dFtD3p3ZrQ3hpoDtoK70ioIAjjH aIXIAcm3FGZFXy503DOA0KaTWwvOVdYCFLm3zWuSOmrX/GsEc7ovasOWwjPn878qVjbUKWwx Q4QkF4OhUV9zPtf9tDSAZ3x7QSwoKbCoRCZ/xbyTUPyQ1VvNy/mYrBcYlzHodsaqUDjHuW+I SQQYEQIACQUCRND5ggIbDAAKCRBy3lIGd+N/BCO8AJ9j1dWVQWxw/YdTbEyrRKOY8YZNwwCf afMAg8QvmOWnHx3wl8WslCaXaE8= Message-ID: <00fb0227-efd3-e1a2-4178-15bdf6f26712@FreeBSD.org> Date: Thu, 19 Nov 2020 15:13:25 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <9fd00098-0ce9-627e-0163-7ede5aa18d6f@FreeBSD.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Nov 2020 23:13:27 -0000 On 11/19/20 2:55 PM, John Baldwin wrote: > On 11/9/20 1:49 PM, Michael Tuexen wrote: >> Author: tuexen >> Date: Mon Nov 9 21:49:40 2020 >> New Revision: 367530 >> URL: https://svnweb.freebsd.org/changeset/base/367530 >> >> Log: >> RFC 7323 specifies that: >> * TCP segments without timestamps should be dropped when support for >> the timestamp option has been negotiated. >> * TCP segments with timestamps should be processed normally if support >> for the timestamp option has not been negotiated. >> This patch enforces the above. >> >> PR: 250499 >> Reviewed by: gnn, rrs >> MFC after: 1 week >> Sponsored by: Netflix, Inc >> Differential Revision: https://reviews.freebsd.org/D27148 >> >> Modified: >> head/sys/netinet/tcp_input.c >> head/sys/netinet/tcp_stacks/bbr.c >> head/sys/netinet/tcp_stacks/rack.c >> head/sys/netinet/tcp_syncache.c >> head/sys/netinet/tcp_timewait.c >> >> Modified: head/sys/netinet/tcp_timewait.c >> ============================================================================== >> --- head/sys/netinet/tcp_timewait.c Mon Nov 9 21:19:17 2020 (r367529) >> +++ head/sys/netinet/tcp_timewait.c Mon Nov 9 21:49:40 2020 (r367530) >> @@ -376,7 +376,7 @@ tcp_twstart(struct tcpcb *tp) >> * looking for a pcb in the listen state. Returns 0 otherwise. >> */ >> int >> -tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, >> +tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, >> struct mbuf *m, int tlen) >> { >> struct tcptw *tw; >> @@ -410,6 +410,16 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unu >> */ >> if (thflags & TH_RST) >> goto drop; >> + >> + /* >> + * If timestamps were negotiated during SYN/ACK and a >> + * segment without a timestamp is received, silently drop >> + * the segment. >> + * See section 3.2 of RFC 7323. >> + */ >> + if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) { >> + goto drop; >> + } > > This causes an insta-panic with TOE because toe_4tuple_check() passes in a NULL > pointer for 'to'. I'm working on a fix for that, but perhaps wait to MFC until > the fix is ready so they can be merged together? > > That said, TOE only calls this in the case that it has gotten a new SYN, so I > wonder if it makes sense to apply this check on a new SYN. For a new SYN, > shouldn't we not care if the new connection is using a different timestamp > option from the old connection? The language in RFC 7323 3.2 is all about > segments on an existing connection, not segments from a new connection I think? > > That is, I think we should perhaps move this check after the TH_SYN check so > that a mismatch doesn't prevent recycling? Actually, we move the check below requiring TH_ACK, I think this would fix the TOE case and also DTRT for plain SYNs for non-TOE: diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c index c52eab956303..85f1ccbe40f9 100644 --- a/sys/netinet/tcp_timewait.c +++ b/sys/netinet/tcp_timewait.c @@ -411,16 +411,6 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, if (thflags & TH_RST) goto drop; - /* - * If timestamps were negotiated during SYN/ACK and a - * segment without a timestamp is received, silently drop - * the segment. - * See section 3.2 of RFC 7323. - */ - if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) { - goto drop; - } - #if 0 /* PAWS not needed at the moment */ /* @@ -455,6 +445,16 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, if ((thflags & TH_ACK) == 0) goto drop; + /* + * If timestamps were negotiated during SYN/ACK and a + * segment without a timestamp is received, silently drop + * the segment. + * See section 3.2 of RFC 7323. + */ + if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) { + goto drop; + } + /* * Reset the 2MSL timer if this is a duplicate FIN. */ The commented out PAWS bits would also seem to not be relevant for SYN-only packets? However, I'm less sure of if that bit should be moved later as well. (Or perhaps it should just be removed. It has been #if 0'd since the timewait structure was first added back in 2003 by jlemon@) -- John Baldwin