From nobody Thu Apr 9 05:48:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE11E2EBBB7; Tue, 10 Mar 2026 14:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773153639; cv=none; b=IFS5R4E/Y+MuFyREx6dwPxUJjM90gwPI7ExYBmBw/a1Fv5WTJcQaTY6CHiG2u/4+YiqMI9BP5Q3IGI5XXPyrtsFo/FK+YqwoJRetOhYILejiIQXvlJZd+I9/4+5Y36VxjR3p5rrcz5rJoh+jNQPrXpYPY48D+63LYPsAgzjykJU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773153639; c=relaxed/simple; bh=Z8Nr1QvwMGZovkr0ftgEALk+HzXNA2h8VoVMn52LLrQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=en+9PHFPq4zyJOIAORm7jP5MNf+qw4X/UQQSyBMRDkqqflRW27+vhyjGVhPM9L4qBD7j5FiPM/PHryXhDIbx0tftu8sXsQqt7dD6VMqfS8HbNdQmZXXZtRJNVEknIFwT3Ki9hSv3XYApTwUSmkyYCrqiwGvHlkKS3Zp4dDGyMlY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IIFsxyJz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IIFsxyJz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40FD4C2BC86; Tue, 10 Mar 2026 14:40:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773153639; bh=Z8Nr1QvwMGZovkr0ftgEALk+HzXNA2h8VoVMn52LLrQ=; h=From:To:Cc:Subject:Date:From; b=IIFsxyJzZNgb8vuPt4nqXC3ZeBA2n8EWvymkZZ8hsMTEKpqxNqUKkAmAR2XYQuT3U 4v/tpkrMl3PLErwHNsjF62eOFi6SmPNgjn7s87LaGQRh2iTyWsO3x8GQNCuCLzNYTh c5RzFcIqRKFV2Li63m4PB9tEnNydLr45tkjO5uGzCl7b25JEklqixm3SgikDP4v29B ff8vg/aNTvxo2v7BgG6P/ADVHMBtlV7/LYv6sGzhDV5zrobeUCMW49yNpNT2e9F1G9 UltXPEqJzL+mwL3VDbLvoQDDBfYWW9JZWCzqDyla5am9enbx7Aitq9ngY7PhoylJlw OiH7xbRUXmgKw== From: "Christophe Leroy (CS GROUP)" To: Alexander Viro , Christian Brauner , Jan Kara , Linus Torvalds , Thomas Gleixner , David Laight Cc: "Christophe Leroy (CS GROUP)" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs: Replace user_access_{begin/end} by scoped user access Date: Tue, 10 Mar 2026 15:40:25 +0100 Message-ID: <5021aa325554b3d2437341514ab0a2977e158274.1773153431.git.chleroy@kernel.org> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8333; i=chleroy@kernel.org; h=from:subject:message-id; bh=Z8Nr1QvwMGZovkr0ftgEALk+HzXNA2h8VoVMn52LLrQ=; b=owGbwMvMwCV2d0KB2p7V54MZT6slMWRu0I10iOWVK5ft8jw48Wh19D6XquUrVFMnht9KYRCVc xO1bJvQUcrCIMbFICumyHL8P/euGV1fUvOn7tKHmcPKBDKEgYtTACai94mRYdpPXYHUG85PSn9f XOhwjufhBr+lm3olXPol39nP+FLvMI2R4b+6sJFU5/65tTL6qsdUZlpkLj/6PdRYMvAqLz+Hp9F qdgA= X-Developer-Key: i=chleroy@kernel.org; a=openpgp; fpr=10FFE6F8B390DE17ACC2632368A92FEB01B8DD78 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Scoped user access reduces code complexity and seamlessly bring masked user access on architectures that support it. Replace user_access_begin/user_access_end blocks in fs by scoped user access. Signed-off-by: Christophe Leroy (CS GROUP) --- fs/readdir.c | 92 +++++++++++++++++++++------------------------------- fs/select.c | 33 ++++++++----------- 2 files changed, 50 insertions(+), 75 deletions(-) diff --git a/fs/readdir.c b/fs/readdir.c index 73707b6816e9..3ebe4adbe36c 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -198,18 +198,15 @@ static bool fillonedir(struct dir_context *ctx, const= char *name, int namlen, } buf->result++; dirent =3D buf->dirent; - if (!user_write_access_begin(dirent, + scoped_user_write_access_size(dirent, (unsigned long)(dirent->d_name + namlen + 1) - - (unsigned long)dirent)) - goto efault; - unsafe_put_user(d_ino, &dirent->d_ino, efault_end); - unsafe_put_user(offset, &dirent->d_offset, efault_end); - unsafe_put_user(namlen, &dirent->d_namlen, efault_end); - unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_write_access_end(); + (unsigned long)dirent, efault) { + unsafe_put_user(d_ino, &dirent->d_ino, efault); + unsafe_put_user(offset, &dirent->d_offset, efault); + unsafe_put_user(namlen, &dirent->d_namlen, efault); + unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault); + } return true; -efault_end: - user_write_access_end(); efault: buf->result =3D -EFAULT; return false; @@ -287,23 +284,19 @@ static bool filldir(struct dir_context *ctx, const ch= ar *name, int namlen, return false; dirent =3D buf->current_dir; prev =3D (void __user *) dirent - prev_reclen; - if (!user_write_access_begin(prev, reclen + prev_reclen)) - goto efault; - - /* This might be 'dirent->d_off', but if so it will get overwritten */ - unsafe_put_user(offset, &prev->d_off, efault_end); - unsafe_put_user(d_ino, &dirent->d_ino, efault_end); - unsafe_put_user(reclen, &dirent->d_reclen, efault_end); - unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); - unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_write_access_end(); + scoped_user_write_access_size(prev, reclen + prev_reclen, efault) { + /* This might be 'dirent->d_off', but if so it will get overwritten */ + unsafe_put_user(offset, &prev->d_off, efault); + unsafe_put_user(d_ino, &dirent->d_ino, efault); + unsafe_put_user(reclen, &dirent->d_reclen, efault); + unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault); + unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault); + } =20 buf->current_dir =3D (void __user *)dirent + reclen; buf->prev_reclen =3D reclen; ctx->count -=3D reclen; return true; -efault_end: - user_write_access_end(); efault: buf->error =3D -EFAULT; return false; @@ -371,24 +364,20 @@ static bool filldir64(struct dir_context *ctx, const = char *name, int namlen, return false; dirent =3D buf->current_dir; prev =3D (void __user *)dirent - prev_reclen; - if (!user_write_access_begin(prev, reclen + prev_reclen)) - goto efault; - - /* This might be 'dirent->d_off', but if so it will get overwritten */ - unsafe_put_user(offset, &prev->d_off, efault_end); - unsafe_put_user(ino, &dirent->d_ino, efault_end); - unsafe_put_user(reclen, &dirent->d_reclen, efault_end); - unsafe_put_user(d_type, &dirent->d_type, efault_end); - unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_write_access_end(); + scoped_user_write_access_size(prev, reclen + prev_reclen, efault) { + /* This might be 'dirent->d_off', but if so it will get overwritten */ + unsafe_put_user(offset, &prev->d_off, efault); + unsafe_put_user(ino, &dirent->d_ino, efault); + unsafe_put_user(reclen, &dirent->d_reclen, efault); + unsafe_put_user(d_type, &dirent->d_type, efault); + unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault); + } =20 buf->prev_reclen =3D reclen; buf->current_dir =3D (void __user *)dirent + reclen; ctx->count -=3D reclen; return true; =20 -efault_end: - user_write_access_end(); efault: buf->error =3D -EFAULT; return false; @@ -460,18 +449,15 @@ static bool compat_fillonedir(struct dir_context *ctx= , const char *name, } buf->result++; dirent =3D buf->dirent; - if (!user_write_access_begin(dirent, + scoped_user_write_access_size(dirent, (unsigned long)(dirent->d_name + namlen + 1) - - (unsigned long)dirent)) - goto efault; - unsafe_put_user(d_ino, &dirent->d_ino, efault_end); - unsafe_put_user(offset, &dirent->d_offset, efault_end); - unsafe_put_user(namlen, &dirent->d_namlen, efault_end); - unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_write_access_end(); + (unsigned long)dirent), efault) { + unsafe_put_user(d_ino, &dirent->d_ino, efault); + unsafe_put_user(offset, &dirent->d_offset, efault); + unsafe_put_user(namlen, &dirent->d_namlen, efault); + unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault); + } return true; -efault_end: - user_write_access_end(); efault: buf->result =3D -EFAULT; return false; @@ -543,22 +529,18 @@ static bool compat_filldir(struct dir_context *ctx, c= onst char *name, int namlen return false; dirent =3D buf->current_dir; prev =3D (void __user *) dirent - prev_reclen; - if (!user_write_access_begin(prev, reclen + prev_reclen)) - goto efault; - - unsafe_put_user(offset, &prev->d_off, efault_end); - unsafe_put_user(d_ino, &dirent->d_ino, efault_end); - unsafe_put_user(reclen, &dirent->d_reclen, efault_end); - unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); - unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_write_access_end(); + scoped_user_write_access_size(prev, reclen + prev_reclen, efault); + unsafe_put_user(offset, &prev->d_off, efault); + unsafe_put_user(d_ino, &dirent->d_ino, efault); + unsafe_put_user(reclen, &dirent->d_reclen, efault); + unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault); + unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault); + } =20 buf->prev_reclen =3D reclen; buf->current_dir =3D (void __user *)dirent + reclen; ctx->count -=3D reclen; return true; -efault_end: - user_write_access_end(); efault: buf->error =3D -EFAULT; return false; diff --git a/fs/select.c b/fs/select.c index e0244dbe4429..7cf80568ff78 100644 --- a/fs/select.c +++ b/fs/select.c @@ -1004,17 +1004,17 @@ static int do_sys_poll(struct pollfd __user *ufds, = unsigned int nfds, fdcount =3D do_poll(head, &table, end_time); poll_freewait(&table); =20 - if (!user_write_access_begin(ufds, nfds * sizeof(*ufds))) - goto out_fds; + scoped_user_write_access_size(ufds, nfds * sizeof(*ufds), out_fds) { + struct pollfd __user *_ufds =3D ufds; =20 - for (walk =3D head; walk; walk =3D walk->next) { - struct pollfd *fds =3D walk->entries; - unsigned int j; + for (walk =3D head; walk; walk =3D walk->next) { + struct pollfd *fds =3D walk->entries; + unsigned int j; =20 - for (j =3D walk->len; j; fds++, ufds++, j--) - unsafe_put_user(fds->revents, &ufds->revents, Efault); - } - user_write_access_end(); + for (j =3D walk->len; j; fds++, _ufds++, j--) + unsafe_put_user(fds->revents, &_ufds->revents, out_fds); + } + } =20 err =3D fdcount; out_fds: @@ -1026,11 +1026,6 @@ static int do_sys_poll(struct pollfd __user *ufds, u= nsigned int nfds, } =20 return err; - -Efault: - user_write_access_end(); - err =3D -EFAULT; - goto out_fds; } =20 static long do_restart_poll(struct restart_block *restart_block) @@ -1338,15 +1333,13 @@ static inline int get_compat_sigset_argpack(struct = compat_sigset_argpack *to, struct compat_sigset_argpack __user *from) { if (from) { - if (!user_read_access_begin(from, sizeof(*from))) - return -EFAULT; - unsafe_get_user(to->p, &from->p, Efault); - unsafe_get_user(to->size, &from->size, Efault); - user_read_access_end(); + scoped_user_read_access(from, Efault) { + unsafe_get_user(to->p, &from->p, Efault); + unsafe_get_user(to->size, &from->size, Efault); + } } return 0; Efault: - user_read_access_end(); return -EFAULT; } =20 --=20 2.49.0