From nobody Sun Feb 8 07:46:25 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 C8590175A1; Thu, 25 Jan 2024 23:57:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227058; cv=none; b=J4ouqNL1UeZ9T71jh3ph9t2+lLvf4rVGTFYft0gvVNxV6DX0tbLZNdfHlXFa8HVRdiomtLU1V9mwUmVTt+c2nhMkHajoqRz+rWWr3DS/gl/85NY9D+nM/z1fq8Jd97G3p7x51nvkvdyYqdd1gFqgOLHYcTSuEf/ZeUrdb+jMrYw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227058; c=relaxed/simple; bh=yZBuOVK56XcD+IZGWPAQUigedfDATjZAltUsMaV/oCg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=r0Cb6Q18M/7N8d41M04swciBYTGuNJ9DHTIAfN94cqVYtliLkLeKJi4aBf18UCcATxj/MEDiwzTp8mJP/Q/1akCmdqrvc8Sjb6L9OBCrv8QNGMzlxbdTYgvjQ3dsCcaAtdyZ1j8M9fOkJz8Z+0g7gGKAD+ZyZ4aHSC6E6AAdCYc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=AsXN9eHn; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="AsXN9eHn" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1706227057; x=1737763057; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=yZBuOVK56XcD+IZGWPAQUigedfDATjZAltUsMaV/oCg=; b=AsXN9eHnOETaFKprBaa7HPHK0s94neoXJrTN+3vH99Sk9bxO707483Hp Qkhufllppwk+HZi7/QRnG3b6Y8/icnD/Kpp0RFDLNxN8EkyQtfcv2mt6I Z7SnN9ZW1p1QXVoBhNMbyZE4Lp84XuCbcDz4IQTFMSzjIeyqaP7hc+Srb ZYzATNSaVvp6CGg8tugSfpu4PkWHY53ZvqNEVWrTQo9PPF8s5mUkHT09z yzgClk6rO8oj+0A8OgVr5YGXYAexbbWxatDX9TbPF/ycmfHGMwmMfvBEy Es7U8iYzSmdaDODftDzaO7d5sRVTIdgJaSzTzb9ppPWn2JKwhz3DYwU2E Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10964"; a="15867562" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="15867562" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10964"; a="930191098" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="930191098" Received: from vcostago-mobl3.jf.intel.com ([10.24.14.99]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:34 -0800 From: Vinicius Costa Gomes To: brauner@kernel.org, amir73il@gmail.com, hu1.chen@intel.com Cc: miklos@szeredi.hu, malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, lizhen.you@intel.com, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Vinicius Costa Gomes Subject: [RFC v2 1/4] cleanup: Fix discarded const warning when defining guards Date: Thu, 25 Jan 2024 15:57:20 -0800 Message-ID: <20240125235723.39507-2-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240125235723.39507-1-vinicius.gomes@intel.com> References: <20240125235723.39507-1-vinicius.gomes@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable When defining guards for const types the void* return implicitly discards the const modifier. Be explicit about it. Compiler warning (gcc 13.2.1): ./include/linux/cleanup.h:154:18: warning: return discards =E2=80=98const= =E2=80=99 qualifier from pointer target type [-Wdiscarded-qualifiers] 154 | { return *_T; } | ^~~ ./include/linux/cred.h:193:1: note: in expansion of macro =E2=80=98DEFINE_G= UARD=E2=80=99 193 | DEFINE_GUARD(cred, const struct cred *, _T =3D override_creds_light= (_T), | ^~~~~~~~~~~~ Signed-off-by: Vinicius Costa Gomes --- include/linux/cleanup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h index c2d09bc4f976..ac521c4521cd 100644 --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -151,7 +151,7 @@ static inline class_##_name##_t class_##_name##ext##_co= nstructor(_init_args) \ #define DEFINE_GUARD(_name, _type, _lock, _unlock) \ DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type = _T); \ static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \ - { return *_T; } + { return (void *)*_T; } =20 #define DEFINE_GUARD_COND(_name, _ext, _condlock) \ EXTEND_CLASS(_name, _ext, \ --=20 2.43.0 From nobody Sun Feb 8 07:46:25 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 E4E3B1A731; Thu, 25 Jan 2024 23:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227059; cv=none; b=Suijg7OzZVS0+loNCeS5bmBKi/ShYpeeLEpH5KuZnP+dCFj+oUPTq7wAqQmVm1rKnV5WnO2nbBi+VN3OMVNsVTpZvnHPtVYzNmGhCtftoMi6dqRPn/kRCDifNrg4X/K76gye6MBNm0Cq1mk6kYvYiLG9Ckvzh8waLsLQXht6dfU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227059; c=relaxed/simple; bh=+5d3tyhMXlyo3iELNdYQuZU7PNVS/IBrZgPRKsrWJ48=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; 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charset="utf-8" Add a light version of override/revert_creds(), this should only be used when the credentials in question will outlive the critical section and the critical section doesn't change the ->usage of the credentials. To make their usage less error prone, introduce cleanup guards asto be used like this: guard(cred)(credentials_to_override_and_restore); or this: scoped_guard(cred, credentials_to_override_and_restore) { /* with credentials overridden */ } Signed-off-by: Vinicius Costa Gomes Reviewed-by: Amir Goldstein Suggested-by: Christian Brauner --- include/linux/cred.h | 21 +++++++++++++++++++++ kernel/cred.c | 6 +++--- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/include/linux/cred.h b/include/linux/cred.h index 2976f534a7a3..e9f2237e4bf8 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -172,6 +172,27 @@ static inline bool cap_ambient_invariant_ok(const stru= ct cred *cred) cred->cap_inheritable)); } =20 +/* + * Override creds without bumping reference count. Caller must ensure + * reference remains valid or has taken reference. Almost always not the + * interface you want. Use override_creds()/revert_creds() instead. + */ +static inline const struct cred *override_creds_light(const struct cred *o= verride_cred) +{ + const struct cred *old =3D current->cred; + + rcu_assign_pointer(current->cred, override_cred); + return old; +} + +static inline void revert_creds_light(const struct cred *revert_cred) +{ + rcu_assign_pointer(current->cred, revert_cred); +} + +DEFINE_GUARD(cred, const struct cred *, _T =3D override_creds_light(_T), + revert_creds_light(_T)); + /** * get_new_cred_many - Get references on a new set of credentials * @cred: The new credentials to reference diff --git a/kernel/cred.c b/kernel/cred.c index c033a201c808..f95f71e3ac1d 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -485,7 +485,7 @@ EXPORT_SYMBOL(abort_creds); */ const struct cred *override_creds(const struct cred *new) { - const struct cred *old =3D current->cred; + const struct cred *old; =20 kdebug("override_creds(%p{%ld})", new, atomic_long_read(&new->usage)); @@ -499,7 +499,7 @@ const struct cred *override_creds(const struct cred *ne= w) * visible to other threads under RCU. */ get_new_cred((struct cred *)new); - rcu_assign_pointer(current->cred, new); + old =3D override_creds_light(new); =20 kdebug("override_creds() =3D %p{%ld}", old, atomic_long_read(&old->usage)); @@ -521,7 +521,7 @@ void revert_creds(const struct cred *old) kdebug("revert_creds(%p{%ld})", old, atomic_long_read(&old->usage)); =20 - rcu_assign_pointer(current->cred, old); + revert_creds_light(old); put_cred(override); } EXPORT_SYMBOL(revert_creds); --=20 2.43.0 From nobody Sun Feb 8 07:46:25 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 374D81B278; Thu, 25 Jan 2024 23:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227061; cv=none; b=syDwzh3Z813LQGR11+bBC6WcIhAvH7IdoUFtuD5XzqDf3TBsD5wWGF6TdDjqneOrVmdutcXzsxq5u5LpUyRrVE8TEktiavGsj7jdoxHeaI7FDo/BFTIMCIasKlqbBvzCUsi4yQzpnZFoQJvC5Fgq8TwB9zDaIMNEyKF0F8KhT1w= ARC-Message-Signature: i=1; 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d="scan'208";a="930191104" Received: from vcostago-mobl3.jf.intel.com ([10.24.14.99]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:36 -0800 From: Vinicius Costa Gomes To: brauner@kernel.org, amir73il@gmail.com, hu1.chen@intel.com Cc: miklos@szeredi.hu, malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, lizhen.you@intel.com, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Vinicius Costa Gomes Subject: [RFC v2 3/4] overlayfs: Optimize credentials usage Date: Thu, 25 Jan 2024 15:57:22 -0800 Message-ID: <20240125235723.39507-4-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240125235723.39507-1-vinicius.gomes@intel.com> References: <20240125235723.39507-1-vinicius.gomes@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" File operations in overlayfs also check against the credentials of the mounter task, stored in the superblock, this credentials will outlive most of the operations. For these cases, use the recently introduced guard statements to guarantee that override/revert_creds() are paired. Signed-off-by: Vinicius Costa Gomes --- fs/overlayfs/copy_up.c | 4 +-- fs/overlayfs/dir.c | 22 +++++++------ fs/overlayfs/file.c | 70 ++++++++++++++++++++++-------------------- fs/overlayfs/inode.c | 60 +++++++++++++++++++----------------- fs/overlayfs/namei.c | 21 ++++++------- fs/overlayfs/readdir.c | 18 +++++------ fs/overlayfs/util.c | 23 +++++++------- fs/overlayfs/xattrs.c | 34 ++++++++++---------- 8 files changed, 130 insertions(+), 122 deletions(-) diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b8e25ca51016..55d1f2b60775 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -1202,7 +1202,8 @@ static int ovl_copy_up_flags(struct dentry *dentry, i= nt flags) if (err) return err; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); while (!err) { struct dentry *next; struct dentry *parent =3D NULL; @@ -1227,7 +1228,6 @@ static int ovl_copy_up_flags(struct dentry *dentry, i= nt flags) dput(parent); dput(next); } - revert_creds(old_cred); =20 return err; } diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 0f8b4a719237..5aa43a3a7b3e 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -687,9 +687,9 @@ static int ovl_set_link_redirect(struct dentry *dentry) const struct cred *old_cred; int err; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); err =3D ovl_set_redirect(dentry, false); - revert_creds(old_cred); =20 return err; } @@ -894,12 +894,13 @@ static int ovl_do_remove(struct dentry *dentry, bool = is_dir) if (err) goto out; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - if (!lower_positive) - err =3D ovl_remove_upper(dentry, is_dir, &list); - else - err =3D ovl_remove_and_whiteout(dentry, &list); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) { + if (!lower_positive) + err =3D ovl_remove_upper(dentry, is_dir, &list); + else + err =3D ovl_remove_and_whiteout(dentry, &list); + } if (!err) { if (is_dir) clear_nlink(dentry->d_inode); @@ -1146,7 +1147,8 @@ static int ovl_rename(struct mnt_idmap *idmap, struct= inode *olddir, goto out; } =20 - old_cred =3D ovl_override_creds(old->d_sb); + old_cred =3D ovl_creds(old->d_sb); + old_cred =3D override_creds_light(old_cred); =20 if (!list_empty(&list)) { opaquedir =3D ovl_clear_empty(new, &list); @@ -1279,7 +1281,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct= inode *olddir, out_unlock: unlock_rename(new_upperdir, old_upperdir); out_revert_creds: - revert_creds(old_cred); + revert_creds_light(old_cred); if (update_nlink) ovl_nlink_end(new); else diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 05536964d37f..482bf78555e2 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -42,7 +42,8 @@ static struct file *ovl_open_realfile(const struct file *= file, if (flags & O_APPEND) acc_mode |=3D MAY_APPEND; =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); real_idmap =3D mnt_idmap(realpath->mnt); err =3D inode_permission(real_idmap, realinode, MAY_OPEN | acc_mode); if (err) { @@ -54,7 +55,6 @@ static struct file *ovl_open_realfile(const struct file *= file, realfile =3D backing_file_open(&file->f_path, flags, realpath, current_cred()); } - revert_creds(old_cred); =20 pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n", file, file, ovl_whatisit(inode, realinode), file->f_flags, @@ -214,9 +214,9 @@ static loff_t ovl_llseek(struct file *file, loff_t offs= et, int whence) ovl_inode_lock(inode); real.file->f_pos =3D file->f_pos; =20 - old_cred =3D ovl_override_creds(inode->i_sb); - ret =3D vfs_llseek(real.file, offset, whence); - revert_creds(old_cred); + old_cred =3D ovl_creds(inode->i_sb); + scoped_guard(cred, old_cred) + ret =3D vfs_llseek(real.file, offset, whence); =20 file->f_pos =3D real.file->f_pos; ovl_inode_unlock(inode); @@ -388,7 +388,6 @@ static ssize_t ovl_splice_write(struct pipe_inode_info = *pipe, struct file *out, static int ovl_fsync(struct file *file, loff_t start, loff_t end, int data= sync) { struct fd real; - const struct cred *old_cred; int ret; =20 ret =3D ovl_sync_status(OVL_FS(file_inode(file)->i_sb)); @@ -401,9 +400,11 @@ static int ovl_fsync(struct file *file, loff_t start, = loff_t end, int datasync) =20 /* Don't sync lower file for fear of receiving EROFS error */ if (file_inode(real.file) =3D=3D ovl_inode_upper(file_inode(file))) { - old_cred =3D ovl_override_creds(file_inode(file)->i_sb); + const struct cred *old_cred; + + old_cred =3D ovl_creds(file_inode(file)->i_sb); + guard(cred)(old_cred); ret =3D vfs_fsync_range(real.file, start, end, datasync); - revert_creds(old_cred); } =20 fdput(real); @@ -441,9 +442,9 @@ static long ovl_fallocate(struct file *file, int mode, = loff_t offset, loff_t len if (ret) goto out_unlock; =20 - old_cred =3D ovl_override_creds(file_inode(file)->i_sb); - ret =3D vfs_fallocate(real.file, mode, offset, len); - revert_creds(old_cred); + old_cred =3D ovl_creds(file_inode(file)->i_sb); + scoped_guard(cred, old_cred) + ret =3D vfs_fallocate(real.file, mode, offset, len); =20 /* Update size */ ovl_file_modified(file); @@ -466,9 +467,9 @@ static int ovl_fadvise(struct file *file, loff_t offset= , loff_t len, int advice) if (ret) return ret; =20 - old_cred =3D ovl_override_creds(file_inode(file)->i_sb); - ret =3D vfs_fadvise(real.file, offset, len, advice); - revert_creds(old_cred); + old_cred =3D ovl_creds(file_inode(file)->i_sb); + scoped_guard(cred, old_cred) + ret =3D vfs_fadvise(real.file, offset, len, advice); =20 fdput(real); =20 @@ -509,25 +510,25 @@ static loff_t ovl_copyfile(struct file *file_in, loff= _t pos_in, goto out_unlock; } =20 - old_cred =3D ovl_override_creds(file_inode(file_out)->i_sb); - switch (op) { - case OVL_COPY: - ret =3D vfs_copy_file_range(real_in.file, pos_in, - real_out.file, pos_out, len, flags); - break; + old_cred =3D ovl_creds(file_inode(file_out)->i_sb); + scoped_guard(cred, old_cred) + switch (op) { + case OVL_COPY: + ret =3D vfs_copy_file_range(real_in.file, pos_in, + real_out.file, pos_out, len, flags); + break; =20 - case OVL_CLONE: - ret =3D vfs_clone_file_range(real_in.file, pos_in, - real_out.file, pos_out, len, flags); - break; + case OVL_CLONE: + ret =3D vfs_clone_file_range(real_in.file, pos_in, + real_out.file, pos_out, len, flags); + break; =20 - case OVL_DEDUPE: - ret =3D vfs_dedupe_file_range_one(real_in.file, pos_in, - real_out.file, pos_out, len, - flags); - break; - } - revert_creds(old_cred); + case OVL_DEDUPE: + ret =3D vfs_dedupe_file_range_one(real_in.file, pos_in, + real_out.file, pos_out, len, + flags); + break; + } =20 /* Update size */ ovl_file_modified(file_out); @@ -579,7 +580,6 @@ static loff_t ovl_remap_file_range(struct file *file_in= , loff_t pos_in, static int ovl_flush(struct file *file, fl_owner_t id) { struct fd real; - const struct cred *old_cred; int err; =20 err =3D ovl_real_fdget(file, &real); @@ -587,9 +587,11 @@ static int ovl_flush(struct file *file, fl_owner_t id) return err; =20 if (real.file->f_op->flush) { - old_cred =3D ovl_override_creds(file_inode(file)->i_sb); + const struct cred *old_cred; + + old_cred =3D ovl_creds(file_inode(file)->i_sb); + guard(cred)(old_cred); err =3D real.file->f_op->flush(real.file, id); - revert_creds(old_cred); } fdput(real); =20 diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index c63b31a460be..9047f245ba0b 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -79,9 +79,10 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *= dentry, goto out_put_write; =20 inode_lock(upperdentry->d_inode); - old_cred =3D ovl_override_creds(dentry->d_sb); - err =3D ovl_do_notify_change(ofs, upperdentry, attr); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + err =3D ovl_do_notify_change(ofs, upperdentry, attr); + if (!err) ovl_copyattr(dentry->d_inode); inode_unlock(upperdentry->d_inode); @@ -170,7 +171,8 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct p= ath *path, metacopy_blocks =3D ovl_is_metacopy_dentry(dentry); =20 type =3D ovl_path_real(dentry, &realpath); - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); err =3D ovl_do_getattr(&realpath, stat, request_mask, flags); if (err) goto out; @@ -281,8 +283,6 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct p= ath *path, stat->nlink =3D dentry->d_inode->i_nlink; =20 out: - revert_creds(old_cred); - return err; } =20 @@ -310,7 +310,9 @@ int ovl_permission(struct mnt_idmap *idmap, if (err) return err; =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); + if (!upperinode && !special_file(realinode->i_mode) && mask & MAY_WRITE) { mask &=3D ~(MAY_WRITE | MAY_APPEND); @@ -318,7 +320,6 @@ int ovl_permission(struct mnt_idmap *idmap, mask |=3D MAY_READ; } err =3D inode_permission(mnt_idmap(realpath.mnt), realinode, mask); - revert_creds(old_cred); =20 return err; } @@ -333,9 +334,10 @@ static const char *ovl_get_link(struct dentry *dentry, if (!dentry) return ERR_PTR(-ECHILD); =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); p =3D vfs_get_link(ovl_dentry_real(dentry), done); - revert_creds(old_cred); + return p; } =20 @@ -468,9 +470,9 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idma= p, } else { const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); acl =3D ovl_get_acl_path(&realpath, posix_acl_xattr_name(type), noperm); - revert_creds(old_cred); } =20 return acl; @@ -496,10 +498,11 @@ static int ovl_set_or_remove_acl(struct dentry *dentr= y, struct inode *inode, struct posix_acl *real_acl; =20 ovl_path_lower(dentry, &realpath); - old_cred =3D ovl_override_creds(dentry->d_sb); - real_acl =3D vfs_get_acl(mnt_idmap(realpath.mnt), realdentry, - acl_name); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + real_acl =3D vfs_get_acl(mnt_idmap(realpath.mnt), realdentry, + acl_name); + if (IS_ERR(real_acl)) { err =3D PTR_ERR(real_acl); goto out; @@ -519,12 +522,13 @@ static int ovl_set_or_remove_acl(struct dentry *dentr= y, struct inode *inode, if (err) goto out; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - if (acl) - err =3D ovl_do_set_acl(ofs, realdentry, acl_name, acl); - else - err =3D ovl_do_remove_acl(ofs, realdentry, acl_name); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) { + if (acl) + err =3D ovl_do_set_acl(ofs, realdentry, acl_name, acl); + else + err =3D ovl_do_remove_acl(ofs, realdentry, acl_name); + } ovl_drop_write(dentry); =20 /* copy c/mtime */ @@ -599,9 +603,9 @@ static int ovl_fiemap(struct inode *inode, struct fiema= p_extent_info *fieinfo, if (!realinode->i_op->fiemap) return -EOPNOTSUPP; =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); err =3D realinode->i_op->fiemap(realinode, fieinfo, start, len); - revert_creds(old_cred); =20 return err; } @@ -661,7 +665,8 @@ int ovl_fileattr_set(struct mnt_idmap *idmap, if (err) goto out; =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); /* * Store immutable/append-only flags in xattr and clear them * in upper fileattr (in case they were set by older kernel) @@ -672,7 +677,6 @@ int ovl_fileattr_set(struct mnt_idmap *idmap, err =3D ovl_set_protattr(inode, upperpath.dentry, fa); if (!err) err =3D ovl_real_fileattr_set(&upperpath, fa); - revert_creds(old_cred); ovl_drop_write(dentry); =20 /* @@ -731,10 +735,10 @@ int ovl_fileattr_get(struct dentry *dentry, struct fi= leattr *fa) =20 ovl_path_real(dentry, &realpath); =20 - old_cred =3D ovl_override_creds(inode->i_sb); + old_cred =3D ovl_creds(inode->i_sb); + guard(cred)(old_cred); err =3D ovl_real_fileattr_get(&realpath, fa); ovl_fileattr_prot_flags(inode, fa); - revert_creds(old_cred); =20 return err; } diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 984ffdaeed6c..0b0258c582a0 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -946,13 +946,12 @@ static int ovl_maybe_validate_verity(struct dentry *d= entry) if (!ovl_test_flag(OVL_VERIFIED_DIGEST, inode)) { const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); =20 err =3D ovl_validate_verity(ofs, &metapath, &datapath); if (err =3D=3D 0) ovl_set_flag(OVL_VERIFIED_DIGEST, inode); - - revert_creds(old_cred); } =20 ovl_inode_unlock(inode); @@ -984,9 +983,10 @@ static int ovl_maybe_lookup_lowerdata(struct dentry *d= entry) if (ovl_dentry_lowerdata(dentry)) goto out; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - err =3D ovl_lookup_data_layers(dentry, redirect, &datapath); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + err =3D ovl_lookup_data_layers(dentry, redirect, &datapath); + if (err) goto out_err; =20 @@ -1052,7 +1052,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct d= entry *dentry, if (dentry->d_name.len > ofs->namelen) return ERR_PTR(-ENAMETOOLONG); =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); upperdir =3D ovl_dentry_upper(dentry->d_parent); if (upperdir) { d.mnt =3D ovl_upper_mnt(ofs); @@ -1331,7 +1332,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct d= entry *dentry, =20 ovl_dentry_init_reval(dentry, upperdentry, OVL_I_E(inode)); =20 - revert_creds(old_cred); if (origin_path) { dput(origin_path->dentry); kfree(origin_path); @@ -1355,7 +1355,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct d= entry *dentry, kfree(upperredirect); out: kfree(d.redirect); - revert_creds(old_cred); return ERR_PTR(err); } =20 @@ -1379,7 +1378,8 @@ bool ovl_lower_positive(struct dentry *dentry) if (!ovl_dentry_upper(dentry)) return true; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); /* Positive upper -> have to look up lower to see whether it exists */ for (i =3D 0; !done && !positive && i < ovl_numlower(poe); i++) { struct dentry *this; @@ -1412,7 +1412,6 @@ bool ovl_lower_positive(struct dentry *dentry) dput(this); } } - revert_creds(old_cred); =20 return positive; } diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index e71156baa7bc..58ea942921fc 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -275,7 +275,8 @@ static int ovl_check_whiteouts(const struct path *path,= struct ovl_readdir_data struct dentry *dentry, *dir =3D path->dentry; const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(rdd->dentry->d_sb); + old_cred =3D ovl_creds(rdd->dentry->d_sb); + guard(cred)(old_cred); =20 err =3D down_write_killable(&dir->d_inode->i_rwsem); if (!err) { @@ -290,7 +291,6 @@ static int ovl_check_whiteouts(const struct path *path,= struct ovl_readdir_data } inode_unlock(dir->d_inode); } - revert_creds(old_cred); =20 return err; } @@ -755,7 +755,8 @@ static int ovl_iterate(struct file *file, struct dir_co= ntext *ctx) const struct cred *old_cred; int err; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); if (!ctx->pos) ovl_dir_reset(file); =20 @@ -807,7 +808,6 @@ static int ovl_iterate(struct file *file, struct dir_co= ntext *ctx) } err =3D 0; out: - revert_creds(old_cred); return err; } =20 @@ -857,9 +857,9 @@ static struct file *ovl_dir_open_realfile(const struct = file *file, struct file *res; const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(file_inode(file)->i_sb); + old_cred =3D ovl_creds(file_inode(file)->i_sb); + guard(cred)(old_cred); res =3D ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE)); - revert_creds(old_cred); =20 return res; } @@ -984,9 +984,9 @@ int ovl_check_empty_dir(struct dentry *dentry, struct l= ist_head *list) struct rb_root root =3D RB_ROOT; const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - err =3D ovl_dir_read_merged(dentry, list, &root); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + err =3D ovl_dir_read_merged(dentry, list, &root); if (err) return err; =20 diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 0217094c23ea..7ba8449d920e 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -1157,15 +1157,16 @@ int ovl_nlink_start(struct dentry *dentry) if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode)) return 0; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - /* - * The overlay inode nlink should be incremented/decremented IFF the - * upper operation succeeds, along with nlink change of upper inode. - * Therefore, before link/unlink/rename, we store the union nlink - * value relative to the upper inode nlink in an upper inode xattr. - */ - err =3D ovl_set_nlink_upper(dentry); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) { + /* + * The overlay inode nlink should be incremented/decremented IFF the + * upper operation succeeds, along with nlink change of upper inode. + * Therefore, before link/unlink/rename, we store the union nlink + * value relative to the upper inode nlink in an upper inode xattr. + */ + err =3D ovl_set_nlink_upper(dentry); + } if (err) goto out_drop_write; =20 @@ -1188,9 +1189,9 @@ void ovl_nlink_end(struct dentry *dentry) if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink =3D=3D 0) { const struct cred *old_cred; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); ovl_cleanup_index(dentry); - revert_creds(old_cred); } =20 ovl_inode_unlock(inode); diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c index 383978e4663c..921a7d086fa1 100644 --- a/fs/overlayfs/xattrs.c +++ b/fs/overlayfs/xattrs.c @@ -45,9 +45,9 @@ static int ovl_xattr_set(struct dentry *dentry, struct in= ode *inode, const char =20 if (!value && !upperdentry) { ovl_path_lower(dentry, &realpath); - old_cred =3D ovl_override_creds(dentry->d_sb); - err =3D vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + err =3D vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0= ); if (err < 0) goto out; } @@ -64,15 +64,16 @@ static int ovl_xattr_set(struct dentry *dentry, struct = inode *inode, const char if (err) goto out; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - if (value) { - err =3D ovl_do_setxattr(ofs, realdentry, name, value, size, - flags); - } else { - WARN_ON(flags !=3D XATTR_REPLACE); - err =3D ovl_do_removexattr(ofs, realdentry, name); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) { + if (value) { + err =3D ovl_do_setxattr(ofs, realdentry, name, value, size, + flags); + } else { + WARN_ON(flags !=3D XATTR_REPLACE); + err =3D ovl_do_removexattr(ofs, realdentry, name); + } } - revert_creds(old_cred); ovl_drop_write(dentry); =20 /* copy c/mtime */ @@ -89,9 +90,9 @@ static int ovl_xattr_get(struct dentry *dentry, struct in= ode *inode, const char struct path realpath; =20 ovl_i_path_real(inode, &realpath); - old_cred =3D ovl_override_creds(dentry->d_sb); + old_cred =3D ovl_creds(dentry->d_sb); + guard(cred)(old_cred); res =3D vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry, name, valu= e, size); - revert_creds(old_cred); return res; } =20 @@ -119,9 +120,9 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list= , size_t size) const struct cred *old_cred; size_t prefix_len, name_len; =20 - old_cred =3D ovl_override_creds(dentry->d_sb); - res =3D vfs_listxattr(realdentry, list, size); - revert_creds(old_cred); + old_cred =3D ovl_creds(dentry->d_sb); + scoped_guard(cred, old_cred) + res =3D vfs_listxattr(realdentry, list, size); if (res <=3D 0 || size =3D=3D 0) return res; =20 @@ -268,4 +269,3 @@ const struct xattr_handler * const *ovl_xattr_handlers(= struct ovl_fs *ofs) return ofs->config.userxattr ? ovl_user_xattr_handlers : ovl_trusted_xattr_handlers; } - --=20 2.43.0 From nobody Sun Feb 8 07:46:25 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 D49961B59A; 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a="15867575" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="15867575" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10964"; a="930191107" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="930191107" Received: from vcostago-mobl3.jf.intel.com ([10.24.14.99]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:36 -0800 From: Vinicius Costa Gomes To: brauner@kernel.org, amir73il@gmail.com, hu1.chen@intel.com Cc: miklos@szeredi.hu, malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, lizhen.you@intel.com, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Vinicius Costa Gomes Subject: [RFC v2 4/4] fs: Optimize credentials reference count for backing file ops Date: Thu, 25 Jan 2024 15:57:23 -0800 Message-ID: <20240125235723.39507-5-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240125235723.39507-1-vinicius.gomes@intel.com> References: <20240125235723.39507-1-vinicius.gomes@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For backing file operations, users are expected to pass credentials that will outlive the backing file common operations. Use the specialized guard statements to override/revert the credentials. Signed-off-by: Vinicius Costa Gomes --- fs/backing-file.c | 124 ++++++++++++++++++++++------------------------ 1 file changed, 60 insertions(+), 64 deletions(-) diff --git a/fs/backing-file.c b/fs/backing-file.c index a681f38d84d8..9874f09f860f 100644 --- a/fs/backing-file.c +++ b/fs/backing-file.c @@ -140,7 +140,7 @@ ssize_t backing_file_read_iter(struct file *file, struc= t iov_iter *iter, struct backing_file_ctx *ctx) { struct backing_aio *aio =3D NULL; - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -153,29 +153,28 @@ ssize_t backing_file_read_iter(struct file *file, str= uct iov_iter *iter, !(file->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; =20 - old_cred =3D override_creds(ctx->cred); - if (is_sync_kiocb(iocb)) { - rwf_t rwf =3D iocb_to_rw_flags(flags); + scoped_guard(cred, old_cred) { + if (is_sync_kiocb(iocb)) { + rwf_t rwf =3D iocb_to_rw_flags(flags); =20 - ret =3D vfs_iter_read(file, iter, &iocb->ki_pos, rwf); - } else { - ret =3D -ENOMEM; - aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); - if (!aio) - goto out; + ret =3D vfs_iter_read(file, iter, &iocb->ki_pos, rwf); + } else { + ret =3D -ENOMEM; + aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + goto out; =20 - aio->orig_iocb =3D iocb; - kiocb_clone(&aio->iocb, iocb, get_file(file)); - aio->iocb.ki_complete =3D backing_aio_rw_complete; - refcount_set(&aio->ref, 2); - ret =3D vfs_iocb_iter_read(file, &aio->iocb, iter); - backing_aio_put(aio); - if (ret !=3D -EIOCBQUEUED) - backing_aio_cleanup(aio, ret); + aio->orig_iocb =3D iocb; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_complete =3D backing_aio_rw_complete; + refcount_set(&aio->ref, 2); + ret =3D vfs_iocb_iter_read(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret !=3D -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } } out: - revert_creds(old_cred); - if (ctx->accessed) ctx->accessed(ctx->user_file); =20 @@ -187,7 +186,7 @@ ssize_t backing_file_write_iter(struct file *file, stru= ct iov_iter *iter, struct kiocb *iocb, int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -210,39 +209,37 @@ ssize_t backing_file_write_iter(struct file *file, st= ruct iov_iter *iter, */ flags &=3D ~IOCB_DIO_CALLER_COMP; =20 - old_cred =3D override_creds(ctx->cred); - if (is_sync_kiocb(iocb)) { - rwf_t rwf =3D iocb_to_rw_flags(flags); + scoped_guard(cred, old_cred) { + if (is_sync_kiocb(iocb)) { + rwf_t rwf =3D iocb_to_rw_flags(flags); =20 - ret =3D vfs_iter_write(file, iter, &iocb->ki_pos, rwf); - if (ctx->end_write) - ctx->end_write(ctx->user_file); - } else { - struct backing_aio *aio; + ret =3D vfs_iter_write(file, iter, &iocb->ki_pos, rwf); + if (ctx->end_write) + ctx->end_write(ctx->user_file); + } else { + struct backing_aio *aio; =20 - ret =3D backing_aio_init_wq(iocb); - if (ret) - goto out; + ret =3D backing_aio_init_wq(iocb); + if (ret) + return ret; =20 - ret =3D -ENOMEM; - aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); - if (!aio) - goto out; + ret =3D -ENOMEM; + aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + return ret; =20 - aio->orig_iocb =3D iocb; - aio->end_write =3D ctx->end_write; - kiocb_clone(&aio->iocb, iocb, get_file(file)); - aio->iocb.ki_flags =3D flags; - aio->iocb.ki_complete =3D backing_aio_queue_completion; - refcount_set(&aio->ref, 2); - ret =3D vfs_iocb_iter_write(file, &aio->iocb, iter); - backing_aio_put(aio); - if (ret !=3D -EIOCBQUEUED) - backing_aio_cleanup(aio, ret); + aio->orig_iocb =3D iocb; + aio->end_write =3D ctx->end_write; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_flags =3D flags; + aio->iocb.ki_complete =3D backing_aio_queue_completion; + refcount_set(&aio->ref, 2); + ret =3D vfs_iocb_iter_write(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret !=3D -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } } -out: - revert_creds(old_cred); - return ret; } EXPORT_SYMBOL_GPL(backing_file_write_iter); @@ -252,15 +249,15 @@ ssize_t backing_file_splice_read(struct file *in, lof= f_t *ppos, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING))) return -EIO; =20 - old_cred =3D override_creds(ctx->cred); - ret =3D vfs_splice_read(in, ppos, pipe, len, flags); - revert_creds(old_cred); + scoped_guard(cred, old_cred) { + ret =3D vfs_splice_read(in, ppos, pipe, len, flags); + } =20 if (ctx->accessed) ctx->accessed(ctx->user_file); @@ -274,7 +271,7 @@ ssize_t backing_file_splice_write(struct pipe_inode_inf= o *pipe, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING))) @@ -284,12 +281,11 @@ ssize_t backing_file_splice_write(struct pipe_inode_i= nfo *pipe, if (ret) return ret; =20 - old_cred =3D override_creds(ctx->cred); - file_start_write(out); - ret =3D iter_file_splice_write(pipe, out, ppos, len, flags); - file_end_write(out); - revert_creds(old_cred); - + scoped_guard(cred, old_cred) { + file_start_write(out); + ret =3D iter_file_splice_write(pipe, out, ppos, len, flags); + file_end_write(out); + } if (ctx->end_write) ctx->end_write(ctx->user_file); =20 @@ -300,7 +296,7 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write); int backing_file_mmap(struct file *file, struct vm_area_struct *vma, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; int ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) || @@ -312,9 +308,9 @@ int backing_file_mmap(struct file *file, struct vm_area= _struct *vma, =20 vma_set_file(vma, file); =20 - old_cred =3D override_creds(ctx->cred); - ret =3D call_mmap(vma->vm_file, vma); - revert_creds(old_cred); + scoped_guard(cred, old_cred) { + ret =3D call_mmap(vma->vm_file, vma); + } =20 if (ctx->accessed) ctx->accessed(ctx->user_file); --=20 2.43.0