From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2A19C742B9 for ; Fri, 12 Jul 2019 12:20:48 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A7D6821019 for ; Fri, 12 Jul 2019 12:20:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MfDNRCVO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7D6821019 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=GX1DGM4Cmka9SbZhSGxIfHa1kdGyod0JYDWo8QlnQs4=; b=MfDNRCVOUcz8wTTNaeadOPPOu 4oecOA3xIWeybcSGaE3FVdMWtztO/nMWrZuww9Xo3QUMi9uBxB8M28F5z7vRKV39OC65H/oRJ/bp9 TJYlAvll6LtsVMX7tJaJ1IZgxBVFZEmKvB0SRxqIfTdZo7Gdc0r4JH2VIG+HAC0NHw+yrrKIOmgCi F3sf95ZkjzYMrH1c6xtobiogWrd1pdRXNHEKdniCrOIBIEmaicfiIB1JYa7etXpZFofSstXhG3XFr q8LBVb08uIAoQWrXazvMff+6O9yP7yqnrrZc/nO5wogNNasQKT39u2pBXcHni/V+KtICMms8cdzwZ bryPG3BSw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hluXb-0003F9-4u; Fri, 12 Jul 2019 12:20:43 +0000 Received: from mx2.mailbox.org ([80.241.60.215]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hluXX-0003EC-Hl for linux-arm-kernel@lists.infradead.org; Fri, 12 Jul 2019 12:20:41 +0000 Received: from smtp1.mailbox.org (smtp1.mailbox.org [80.241.60.240]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 2AA0EA217D; Fri, 12 Jul 2019 14:20:36 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter01.heinlein-hosting.de (spamfilter01.heinlein-hosting.de [80.241.56.115]) (amavisd-new, port 10030) with ESMTP id Fg_RUaFCSZVH; Fri, 12 Jul 2019 14:20:26 +0200 (CEST) Date: Fri, 12 Jul 2019 22:20:17 +1000 From: Aleksa Sarai To: Al Viro Subject: Re: [PATCH v9 01/10] namei: obey trailing magic-link DAC permissions Message-ID: <20190712122017.xkowq2cjreylpotm@yavin> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-2-cyphar@cyphar.com> <20190712041454.GG17978@ZenIV.linux.org.uk> MIME-Version: 1.0 In-Reply-To: <20190712041454.GG17978@ZenIV.linux.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190712_052039_887714_B265CE80 X-CRM114-Status: GOOD ( 19.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, Andy Lutomirski , Shuah Khan , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Content-Type: multipart/mixed; boundary="===============7491196064534468651==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============7491196064534468651== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="zhpexfjxcruxolbk" Content-Disposition: inline --zhpexfjxcruxolbk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-07-12, Al Viro wrote: > On Sun, Jul 07, 2019 at 12:57:28AM +1000, Aleksa Sarai wrote: > > @@ -514,7 +516,14 @@ static void set_nameidata(struct nameidata *p, int= dfd, struct filename *name) > > p->stack =3D p->internal; > > p->dfd =3D dfd; > > p->name =3D name; > > - p->total_link_count =3D old ? old->total_link_count : 0; > > + p->total_link_count =3D 0; > > + p->acc_mode =3D 0; > > + p->opath_mask =3D FMODE_PATH_READ | FMODE_PATH_WRITE; > > + if (old) { > > + p->total_link_count =3D old->total_link_count; > > + p->acc_mode =3D old->acc_mode; > > + p->opath_mask =3D old->opath_mask; > > + } >=20 > Huh? Could somebody explain why traversals of NFS4 referrals should inhe= rit > ->acc_mode and ->opath_mask? I'll be honest -- I don't understand what set_nameidata() did so I just did what I thought would be an obvious change (to just copy the contents). I thought it was related to some aspect of the symlink stack handling. In that case, should they both be set to 0 on set_nameidata()? This will mean that fd re-opening (or magic-link opening) through a set_nameidata() would always fail. > > static __always_inline > > -const char *get_link(struct nameidata *nd) > > +const char *get_link(struct nameidata *nd, bool trailing) > > { > > struct saved *last =3D nd->stack + nd->depth - 1; > > struct dentry *dentry =3D last->link.dentry; > > @@ -1081,6 +1134,44 @@ const char *get_link(struct nameidata *nd) > > } else { > > res =3D get(dentry, inode, &last->done); > > } > > + /* If we just jumped it was because of a magic-link. */ > > + if (unlikely(nd->flags & LOOKUP_JUMPED)) { > [...] > In any case, this "bool trailing" is completely wrong; whether that > check belongs in trailing_symlink() or (some of) its callers, putting > it into get_link() is a mistake, forced by kludgy check for procfs-style > symlinks. The error path for LOOKUP_JUMPED comes from the old O_BENEATH patchset, but all of the "bool trailing" logic is definitely my gaff (I was quietly hoping you'd have a much better solution than the whole get_link() thing -- it definitely felt very kludgey to write). I will work on the suggestion in your follow-up email. Thanks! --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --zhpexfjxcruxolbk Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXSh6/QAKCRCdlLljIbnQ EjDMAQCLRtfrI0y8gA2T7fw18G0cU799E+TMMczEIjU79f+8jQD/UcfSgUsZT0h6 7dVpliYNzOl4Uou0Y4Kln5It6iq5aAc= =74oH -----END PGP SIGNATURE----- --zhpexfjxcruxolbk-- --===============7491196064534468651== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============7491196064534468651==--