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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 38A48C76195 for ; Wed, 17 Jul 2019 02:12:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F1262173E for ; Wed, 17 Jul 2019 02:12:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726601AbfGQCMi (ORCPT ); Tue, 16 Jul 2019 22:12:38 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:35228 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725951AbfGQCMd (ORCPT ); Tue, 16 Jul 2019 22:12:33 -0400 Received: by mail-pl1-f194.google.com with SMTP id w24so11093962plp.2 for ; Tue, 16 Jul 2019 19:12:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:subject:in-reply-to:cc:from:to:message-id :mime-version:content-transfer-encoding; bh=XJLjYj+DtIYQb0AMLYtaQvMihTCm0rsvCGKlwMRh3LE=; b=Kyz9SYziQlqGrxsTyogHVIqnSlhYdHSkWzVCgiRTF6ahv63Q/xwaP1v61QjAsjDKsF Uy99xBbdb5lF+vNgV0YrB7ot1jDuVCfBMm0eh0EvbyEp3YSIBe0Jxw4+9mp5Zris9Hrk Uh8aRCFbZE10Q4FLCBGCTogaZ9XqHkuBb32vXSldyP4ogvhfsI8GTMPaxLSwm86hexsI /D5qhWstiMCVeDTZftojYXXNVtHX80ke9H0BbyFHCHNrlu1gFYou1noAf/qCXw+Q7JZp sCjpkU2EgrX1LBcbez67iL+iMLWBZFWfxUuB7+pchRnoDvi2Yox7NYcGjAjE11PYDiIy qfnA== X-Gm-Message-State: APjAAAUesLk3yBNMFe1mN1yq074tDLHx3lhpsftDGpO1gRyR/K5XcOmE naJ0oEnAfN1fOmjzLhcxG3E= X-Google-Smtp-Source: APXvYqw1pQN2mCJqE4LloipsyU+ky9ZyfrHyYjD9dGtOKrfKeU8jFTsCJcFJac6EgQIwz1mt6T4pwQ== X-Received: by 2002:a17:902:8546:: with SMTP id d6mr38738719plo.207.1563329552353; Tue, 16 Jul 2019 19:12:32 -0700 (PDT) Received: from localhost ([12.206.222.5]) by smtp.gmail.com with ESMTPSA id 196sm24393369pfy.167.2019.07.16.19.12.31 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 16 Jul 2019 19:12:31 -0700 (PDT) Date: Tue, 16 Jul 2019 19:12:31 -0700 (PDT) X-Google-Original-Date: Tue, 16 Jul 2019 19:12:29 PDT (-0700) Subject: Re: [PATCH v2 2/4] Add fchmodat4(), a new syscall In-Reply-To: <20190717014802.GS17978@ZenIV.linux.org.uk> CC: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, tony.luck@intel.com, fenghua.yu@intel.com, geert@linux-m68k.org, monstr@monstr.eu, ralf@linux-mips.org, paul.burton@mips.com, jhogan@kernel.org, James.Bottomley@hansenpartnership.com, deller@gmx.de, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, peterz@infradead.org, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, dhowells@redhat.com, firoz.khan@linaro.org, stefan@agner.ch, schwidefsky@de.ibm.com, axboe@kernel.dk, christian@brauner.io, hare@suse.com, deepa.kernel@gmail.com, tycho@tycho.ws, kim.phillips@arm.com, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@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, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org From: Palmer Dabbelt To: viro@zeniv.linux.org.uk Message-ID: Mime-Version: 1.0 (MHng) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, 16 Jul 2019 18:48:02 PDT (-0700), viro@zeniv.linux.org.uk wrote: > On Tue, Jul 16, 2019 at 06:27:17PM -0700, Palmer Dabbelt wrote: > >> -int do_fchmodat(int dfd, const char __user *filename, umode_t mode) >> +int do_fchmodat4(int dfd, const char __user *filename, umode_t mode, int flags) >> { >> struct path path; >> int error; >> - unsigned int lookup_flags = LOOKUP_FOLLOW; >> + unsigned int lookup_flags; >> + >> + if (unlikely(flags & ~AT_SYMLINK_NOFOLLOW)) >> + return -EINVAL; >> + >> + lookup_flags = flags & AT_SYMLINK_NOFOLLOW ? 0 : LOOKUP_FOLLOW; >> + > > Why not do that in sys_fchmodat4() itself, passing lookup_flags to > do_fchmodat() and updating old callers to pass it 0 as extra argument? Ya, that seems better -- passing LOOKUP_FOLLOW instead of 0, to keep the behavior the same. That way I could avoid the overhead of these checks for the old syscalls, as we know they're not necessary. I'll replace this patch with the following for a v3 diff --git a/fs/open.c b/fs/open.c index b5b80469b93d..a5f99408af11 100644 --- a/fs/open.c +++ b/fs/open.c @@ -569,11 +569,12 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) return ksys_fchmod(fd, mode); } -int do_fchmodat(int dfd, const char __user *filename, umode_t mode) +int do_fchmodat4(int dfd, const char __user *filename, umode_t mode, + int lookup_flags) { struct path path; int error; - unsigned int lookup_flags = LOOKUP_FOLLOW; + retry: error = user_path_at(dfd, filename, lookup_flags, &path); if (!error) { @@ -587,15 +588,28 @@ int do_fchmodat(int dfd, const char __user *filename, umode_t mode) return error; } +SYSCALL_DEFINE4(fchmodat4, int, dfd, const char __user *, filename, + umode_t, mode, int, flags) +{ + unsigned int lookup_flags; + + if (unlikely(flags & ~AT_SYMLINK_NOFOLLOW)) + return -EINVAL; + + lookup_flags = flags & AT_SYMLINK_NOFOLLOW ? 0 : LOOKUP_FOLLOW; + + return do_fchmodat4(dfd, filename, mode, lookup_flags); +} + SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode) { - return do_fchmodat(dfd, filename, mode); + return do_fchmodat4(dfd, filename, mode, LOOKUP_FOLLOW); } SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) { - return do_fchmodat(AT_FDCWD, filename, mode); + return do_fchmodat4(AT_FDCWD, filename, mode, LOOKUP_FOLLOW); } static int chown_common(const struct path *path, uid_t user, gid_t group) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index e1c20f1d0525..6676b1cc5485 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -81,6 +81,7 @@ struct io_uring_params; #include #include #include +#include #include #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER @@ -433,6 +434,8 @@ asmlinkage long sys_chroot(const char __user *filename); asmlinkage long sys_fchmod(unsigned int fd, umode_t mode); asmlinkage long sys_fchmodat(int dfd, const char __user *filename, umode_t mode); +asmlinkage long sys_fchmodat4(int dfd, const char __user *filename, + umode_t mode, int flags); asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group, int flag); asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group); @@ -1320,11 +1323,12 @@ static inline long ksys_link(const char __user *oldname, return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); } -extern int do_fchmodat(int dfd, const char __user *filename, umode_t mode); +extern int do_fchmodat4(int dfd, const char __user *filename, umode_t mode, + int flags); static inline int ksys_chmod(const char __user *filename, umode_t mode) { - return do_fchmodat(AT_FDCWD, filename, mode); + return do_fchmodat4(AT_FDCWD, filename, mode, LOOKUP_FOLLOW); } extern long do_faccessat(int dfd, const char __user *filename, int mode);