From nobody Thu Jul 21 16:21:46 2022 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4LpdB616ybz4X0R3; Thu, 21 Jul 2022 16:21:50 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4LpdB51z7Wz4MJH; Thu, 21 Jul 2022 16:21:49 +0000 (UTC) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id 26LGLkNe078063; Thu, 21 Jul 2022 09:21:46 -0700 (PDT) (envelope-from freebsd@gndrsh.dnsmgr.net) Received: (from freebsd@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id 26LGLkNn078062; Thu, 21 Jul 2022 09:21:46 -0700 (PDT) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <202207211621.26LGLkNn078062@gndrsh.dnsmgr.net> Subject: Re: git: fb8ef16bab0d - main - IPv4: correct limit on loopback_prefix In-Reply-To: <202207211438.26LEctew070239@gitrepo.freebsd.org> To: Mike Karels Date: Thu, 21 Jul 2022 09:21:46 -0700 (PDT) CC: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Reply-To: rgrimes@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 4LpdB51z7Wz4MJH X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of freebsd@gndrsh.dnsmgr.net has no SPF policy when checking 69.59.192.140) smtp.mailfrom=freebsd@gndrsh.dnsmgr.net X-Spamd-Result: default: False [-2.10 / 15.00]; AUTH_NA(1.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-0.999]; NEURAL_HAM_SHORT(-1.00)[-0.997]; MIME_GOOD(-0.10)[text/plain]; MLMMJ_DEST(0.00)[dev-commits-src-all@freebsd.org,dev-commits-src-main@freebsd.org]; ASN(0.00)[asn:13868, ipnet:69.59.192.0/19, country:US]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_THREE(0.00)[3]; R_SPF_NA(0.00)[no SPF record]; R_DKIM_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; HAS_REPLYTO(0.00)[rgrimes@freebsd.org]; DMARC_NA(0.00)[dnsmgr.net]; RCPT_COUNT_THREE(0.00)[4]; ARC_NA(0.00)[]; RCVD_TLS_LAST(0.00)[]; TO_DN_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; REPLYTO_DOM_NEQ_FROM_DOM(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] X-ThisMailContainsUnwantedMimeParts: N > The branch main has been updated by karels: > > URL: https://cgit.FreeBSD.org/src/commit/?id=fb8ef16bab0d23e185deed5a6b2e44e72ad53d43 > > commit fb8ef16bab0d23e185deed5a6b2e44e72ad53d43 > Author: Mike Karels > AuthorDate: 2022-07-21 13:10:15 +0000 > Commit: Mike Karels > CommitDate: 2022-07-21 14:38:17 +0000 > > IPv4: correct limit on loopback_prefix > > Commit efe58855f3ea allowed the net.inet.ip.loopback_prefix value > to be 32. However, with a 32-bit mask, 127.0.0.1 is not included > in the reserved loopback range, which should not be allowed. > Change the max prefix length to 31. Hummm... 127.0.0.1/32 specifices exactly and ONLY 127.0.0.1, and this should be fine. Looking at the mask calculated below with loopback_prefix=32 this should yeild a mask of 0xffffffff, which appears to be exactly what is correct. What DOES become an issue when /32 is used is that the loopback ROUTE 127.0.0.0/32 is wrong now, but then with a /32 you dont need a network route, as you should have a host route to exactly 127.0.0.1. Can you be more descriptive on what problem arrose with /32? > --- > sys/netinet/in.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sys/netinet/in.c b/sys/netinet/in.c > index c3880c4ba983..1c44623bdec1 100644 > --- a/sys/netinet/in.c > +++ b/sys/netinet/in.c > @@ -297,7 +297,7 @@ sysctl_loopback_prefixlen(SYSCTL_HANDLER_ARGS) > error = sysctl_handle_int(oidp, &preflen, 0, req); > if (error || !req->newptr) > return (error); > - if (preflen < 8 || preflen > 32) > + if (preflen < 8 || preflen > 31) > return (EINVAL); > V_in_loopback_mask = 0xffffffff << (32 - preflen); > return (0); > -- Rod Grimes rgrimes@freebsd.org