From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Date: Fri, 12 Jul 2019 13:39:24 +0100 Message-ID: <20190712123924.GK17978@ZenIV.linux.org.uk> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> <20190712105745.nruaftgeat6irhzr@yavin> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190712105745.nruaftgeat6irhzr@yavin> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Aleksa Sarai 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.orgCh List-Id: linux-arch.vger.kernel.org On Fri, Jul 12, 2019 at 08:57:45PM +1000, Aleksa Sarai wrote: > > > @@ -2350,9 +2400,11 @@ static const char *path_init(struct nameidata *nd, unsigned flags) > > > s = ERR_PTR(error); > > > return s; > > > } > > > - error = dirfd_path_init(nd); > > > - if (unlikely(error)) > > > - return ERR_PTR(error); > > > + if (likely(!nd->path.mnt)) { > > > > Is that a weird way of saying "if we hadn't already called dirfd_path_init()"? > > Yes. I did it to be more consistent with the other "have we got the > root" checks elsewhere. Is there another way you'd prefer I do it? "Have we got the root" checks are inevitable evil; here you are making the control flow in a single function hard to follow. I *think* what you are doing is absolute pathname, no LOOKUP_BENEATH: set_root error = nd_jump_root(nd) else error = dirfd_path_init(nd) return unlikely(error) ? ERR_PTR(error) : s; which should be a lot easier to follow (not to mention shorter), but I might be missing something in all of that. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from zeniv.linux.org.uk ([195.92.253.2]:37880 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729066AbfGLMj6 (ORCPT ); Fri, 12 Jul 2019 08:39:58 -0400 Date: Fri, 12 Jul 2019 13:39:24 +0100 From: Al Viro Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190712123924.GK17978@ZenIV.linux.org.uk> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> <20190712105745.nruaftgeat6irhzr@yavin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190712105745.nruaftgeat6irhzr@yavin> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Aleksa Sarai Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Christian Brauner , David Drysdale , Andy Lutomirski , Linus Torvalds , Eric Biederman , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , Chanho Min , Oleg Nesterov , Aleksa Sarai , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Message-ID: <20190712123924.MbOiRkKo1qyj4c_WiRnBQRSiFcY-rZDR1QhcdSVXBHU@z> On Fri, Jul 12, 2019 at 08:57:45PM +1000, Aleksa Sarai wrote: > > > @@ -2350,9 +2400,11 @@ static const char *path_init(struct nameidata *nd, unsigned flags) > > > s = ERR_PTR(error); > > > return s; > > > } > > > - error = dirfd_path_init(nd); > > > - if (unlikely(error)) > > > - return ERR_PTR(error); > > > + if (likely(!nd->path.mnt)) { > > > > Is that a weird way of saying "if we hadn't already called dirfd_path_init()"? > > Yes. I did it to be more consistent with the other "have we got the > root" checks elsewhere. Is there another way you'd prefer I do it? "Have we got the root" checks are inevitable evil; here you are making the control flow in a single function hard to follow. I *think* what you are doing is absolute pathname, no LOOKUP_BENEATH: set_root error = nd_jump_root(nd) else error = dirfd_path_init(nd) return unlikely(error) ? ERR_PTR(error) : s; which should be a lot easier to follow (not to mention shorter), but I might be missing something in all of that.