From patchwork Wed Jul 17 01:27:17 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Palmer Dabbelt X-Patchwork-Id: 11046883 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 58DEF912 for ; Wed, 17 Jul 2019 01:29:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 491E5286FF for ; Wed, 17 Jul 2019 01:29:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3C0FF2871C; Wed, 17 Jul 2019 01:29:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C4D52286FF for ; Wed, 17 Jul 2019 01:29:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727141AbfGQB3f (ORCPT ); Tue, 16 Jul 2019 21:29:35 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:42360 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726425AbfGQB3Q (ORCPT ); Tue, 16 Jul 2019 21:29:16 -0400 Received: by mail-pl1-f194.google.com with SMTP id ay6so11036557plb.9 for ; Tue, 16 Jul 2019 18:29:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding:cc:from:to; bh=Km6i2EwlnHTMsEa+Chc8B8lkJXrzGe+ncWgEI0oBDH8=; b=DLAJM7oG3ybeUmclWPVZfMhBUnRrw9wGMdXduIn2giXhaGrJ7S5W8yVcEE2KwLFQAh D1fm8Qfvlg4+vU/wK9eEo2SBWGFnrW2QH4msqzaJa2F5Mqtk545ueU4VzXlO2Pka91aE 0ZIjIFL3MsFSMfhP6hasIsWi+LC5nQsPKwISrpKwFjetWndP1gu0y7RwT7xlLsYYY3bX aA9+vRQ2Jy/EGfc2fUemHwW+nDNJKVxhk9EQMc/dKQv4LICHm3AoRl9JnxONdNyJNxBk BKPc4PBCTZeLcTJbqW33HPUobtx12bsfbsrHt2Ek4XDY+qdDSWFBlI6LBq/1RrDbWAwT fAfQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding:cc:from:to; bh=Km6i2EwlnHTMsEa+Chc8B8lkJXrzGe+ncWgEI0oBDH8=; b=qTnhZGi8Z2jH/Rl+pO4h6tTokFcvWtFaeSN4QPEGIPNV2nH9oVGpsHruvSpq9kZRHb jJ+SGqyxf+j0PvOlr1LXrV93XV/SnkyRiheVIyGC32nmzNJ/tPPT/PeAF49r8JTB9y4h dfePAnAvRaBKUiYaH1K/wnls2p+6rFOXwqYXpRlHSilrFT+q3eJKQzB+BOvl9Afd8qBC NCkkcpNNC60IuXUvPp9pqsT4mqGIM+8dYVtzTtvTeiZ3KS0t8Pk8f3eQrsYVMrmfbSuD k76IT1zz2kp0DlUSr8dZIYiFnrRWViYiX4beyV9lk9CzferaPiHZICFk6teVvMeYEOF5 uURg== X-Gm-Message-State: APjAAAWijwKAteN5Bfx4Y57rREju4NWVzM4cIO1VTFBsL0/EW7U0Yy6B c6EkLXJkSPL37MwwZ1O5iDqneQ== X-Google-Smtp-Source: APXvYqy1hMVJ/bl9aSMVuTE5nvwz4oMGbsdCr+A6D4NXU76rmJy3i+4M2pUivduNcdb15I23YjfxXQ== X-Received: by 2002:a17:902:ba96:: with SMTP id k22mr40372539pls.44.1563326954956; Tue, 16 Jul 2019 18:29:14 -0700 (PDT) Received: from localhost ([12.206.222.5]) by smtp.gmail.com with ESMTPSA id s11sm20793710pgv.13.2019.07.16.18.29.13 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 16 Jul 2019 18:29:14 -0700 (PDT) Subject: [PATCH v2 2/4] Add fchmodat4(), a new syscall Date: Tue, 16 Jul 2019 18:27:17 -0700 Message-Id: <20190717012719.5524-3-palmer@sifive.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190717012719.5524-1-palmer@sifive.com> References: <20190717012719.5524-1-palmer@sifive.com> MIME-Version: 1.0 Cc: 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, Arnd Bergmann , peterz@infradead.org, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, Palmer Dabbelt , 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, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP man 3p says that fchmodat() takes a flags argument, but the Linux syscall does not. There doesn't appear to be a good userspace workaround for this issue but the implementation in the kernel is pretty straight-forward. The specific use case where the missing flags came up was WRT a fuse filesystem implemenation, but the functionality is pretty generic so I'm assuming there would be other use cases. Signed-off-by: Palmer Dabbelt --- fs/open.c | 20 ++++++++++++++++---- include/linux/syscalls.h | 7 +++++-- 2 files changed, 21 insertions(+), 6 deletions(-) diff --git a/fs/open.c b/fs/open.c index b5b80469b93d..2f72b4d6a2c1 100644 --- a/fs/open.c +++ b/fs/open.c @@ -569,11 +569,17 @@ 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 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; + retry: error = user_path_at(dfd, filename, lookup_flags, &path); if (!error) { @@ -587,15 +593,21 @@ 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) +{ + return do_fchmodat4(dfd, filename, mode, 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, 0); } SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) { - return do_fchmodat(AT_FDCWD, filename, mode); + return do_fchmodat4(AT_FDCWD, filename, mode, 0); } 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..a4bde25ad264 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -433,6 +433,8 @@ 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 +1322,12 @@ 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, 0); } extern long do_faccessat(int dfd, const char __user *filename, int mode);