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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 30EC1EB64DD for ; Tue, 11 Jul 2023 11:58:22 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4R0fXD55ppz3c09 for ; Tue, 11 Jul 2023 21:58:20 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=softfail (domain owner discourages use of this host) smtp.mailfrom=kernel.org (client-ip=207.211.30.44; helo=us-smtp-delivery-44.mimecast.com; envelope-from=legion@kernel.org; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-44.mimecast.com (unknown [207.211.30.44]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4R0dsM4dlKz30N3 for ; Tue, 11 Jul 2023 21:28:07 +1000 (AEST) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-447-NWZC1GziNDq7Lz0JPSLZRg-1; Tue, 11 Jul 2023 07:26:40 -0400 X-MC-Unique: NWZC1GziNDq7Lz0JPSLZRg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4FAB088D1B7; Tue, 11 Jul 2023 11:26:38 +0000 (UTC) Received: from localhost.localdomain.com (unknown [10.45.225.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id C5A9463F3C; Tue, 11 Jul 2023 11:26:25 +0000 (UTC) From: Alexey Gladkov To: LKML , Arnd Bergmann , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk Subject: [PATCH v3 2/5] fs: Add fchmodat4() Date: Tue, 11 Jul 2023 13:25:43 +0200 Message-Id: In-Reply-To: References: <87o8pscpny.fsf@oldenburg2.str.redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; x-default=true X-Mailman-Approved-At: Tue, 11 Jul 2023 21:56:57 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dalias@libc.org, linux-ia64@vger.kernel.org, fenghua.yu@intel.com, alexander.shishkin@linux.intel.com, Palmer Dabbelt , heiko.carstens@de.ibm.com, x86@kernel.org, stefan@agner.ch, ldv@altlinux.org, dhowells@redhat.com, kim.phillips@arm.com, paulus@samba.org, deepa.kernel@gmail.com, hpa@zytor.com, sparclinux@vger.kernel.org, will@kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, hare@suse.com, ysato@users.sourceforge.jp, deller@gmx.de, linux-sh@vger.kernel.org, linux@armlinux.org.uk, borntraeger@de.ibm.com, mingo@redhat.com, geert@linux-m68k.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, jhogan@kernel.org, firoz.khan@linaro.org, mattst88@gmail.com, fweimer@redhat.com, gor@linux.ibm.com, peterz@infradead.org, glebfm@altlinux.org, tycho@tycho.ws, acme@kernel.org, linux-m68k@lists.linux-m68k.org, bp@alien8.de, luto@kernel.org, namhyung@kernel.org, tglx@linutronix.de, christian@brauner.io, rth@twiddle.net, axboe@kernel.dk, Jame s.Bottomley@HansenPartnership.com, monstr@monstr.eu, tony.luck@intel.com, linux-parisc@vger.kernel.org, linux-mips@vger.kernel.org, ralf@linux-mips.org, paul.burton@mips.com, linux-alpha@vger.kernel.org, schwidefsky@de.ibm.com, ink@jurassic.park.msu.ru, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Palmer Dabbelt On the userspace side fchmodat(3) is implemented as a wrapper function which implements the POSIX-specified interface. This interface differs from the underlying kernel system call, which does not have a flags argument. Most implementations require procfs [1][2]. There doesn't appear to be a good userspace workaround for this issue but the implementation in the kernel is pretty straight-forward. The new fchmodat4() syscall allows to pass the AT_SYMLINK_NOFOLLOW flag, unlike existing fchmodat. [1] https://sourceware.org/git/?p=3Dglibc.git;a=3Dblob;f=3Dsysdeps/unix/sys= v/linux/fchmodat.c;h=3D17eca54051ee28ba1ec3f9aed170a62630959143;hb=3Da492b1= e5ef7ab50c6fdd4e4e9879ea5569ab0a6c#l35 [2] https://git.musl-libc.org/cgit/musl/tree/src/stat/fchmodat.c?id=3D718f3= 63bc2067b6487900eddc9180c84e7739f80#n28 Signed-off-by: Palmer Dabbelt Signed-off-by: Alexey Gladkov --- fs/open.c | 18 ++++++++++++++---- include/linux/syscalls.h | 2 ++ 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/fs/open.c b/fs/open.c index 4478adcc4f3a..58bb88c6afb6 100644 --- a/fs/open.c +++ b/fs/open.c @@ -671,11 +671,11 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mo= de) =09return err; } =20 -static int do_fchmodat(int dfd, const char __user *filename, umode_t mode) +static int do_fchmodat4(int dfd, const char __user *filename, umode_t mode= , int lookup_flags) { =09struct path path; =09int error; -=09unsigned int lookup_flags =3D LOOKUP_FOLLOW; + retry: =09error =3D user_path_at(dfd, filename, lookup_flags, &path); =09if (!error) { @@ -689,15 +689,25 @@ static int do_fchmodat(int dfd, const char __user *fi= lename, umode_t mode) =09return error; } =20 +SYSCALL_DEFINE4(fchmodat4, int, dfd, const char __user *, filename, +=09=09umode_t, mode, int, flags) +{ +=09if (unlikely(flags & ~AT_SYMLINK_NOFOLLOW)) +=09=09return -EINVAL; + +=09return do_fchmodat4(dfd, filename, mode, +=09=09=09flags & AT_SYMLINK_NOFOLLOW ? 0 : LOOKUP_FOLLOW); +} + SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, =09=09umode_t, mode) { -=09return do_fchmodat(dfd, filename, mode); +=09return do_fchmodat4(dfd, filename, mode, LOOKUP_FOLLOW); } =20 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) { -=09return do_fchmodat(AT_FDCWD, filename, mode); +=09return do_fchmodat4(AT_FDCWD, filename, mode, LOOKUP_FOLLOW); } =20 /** diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 497bdd968c32..b17d37d2bad6 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -466,6 +466,8 @@ 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, =09=09=09 umode_t mode); +asmlinkage long sys_fchmodat4(int dfd, const char __user *filename, +=09=09=09 umode_t mode, int flags); asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t u= ser, =09=09=09 gid_t group, int flag); asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group); --=20 2.33.8