linux-kernel - [PATCH 2/5] cifs: Do not add FILE_READ_ATTRIBUTES when using GENERIC

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Message-Id: <20241231223514.15595-2-pali@kernel.org>
Date: Tue, 31 Dec 2024 23:35:11 +0100
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>
Cc: linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] cifs: Do not add FILE_READ_ATTRIBUTES when using GENERIC_READ/EXECUTE/ALL

Individual bits GENERIC_READ, GENERIC_EXECUTE and GENERIC_ALL have meaning
which includes also access right for FILE_READ_ATTRIBUTES. So specifying
FILE_READ_ATTRIBUTES bit together with one of those GENERIC (except
GENERIC_WRITE) does not do anything.

This change prevents calling additional (fallback) code and sending more
requests without FILE_READ_ATTRIBUTES when the primary request fails on
-EACCES, as it is not needed at all.

Signed-off-by: Pali Rohár <pali@...nel.org>
---
 fs/smb/client/smb2file.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c
index 1476cb824ae4..0f3d20b597d6 100644
--- a/fs/smb/client/smb2file.c
+++ b/fs/smb/client/smb2file.c
@@ -158,7 +158,16 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms, __u32
 	if (smb2_path == NULL)
 		return -ENOMEM;
 
+	/*
+	 * GENERIC_READ, GENERIC_EXECUTE, GENERIC_ALL and MAXIMUM_ALLOWED
+	 * contains also FILE_READ_ATTRIBUTES access right. So do not append
+	 * FILE_READ_ATTRIBUTES when not needed and prevent calling code path
+	 * for retry_without_read_attributes.
+	 */
 	if (!(oparms->desired_access & FILE_READ_ATTRIBUTES) &&
+	    !(oparms->desired_access & GENERIC_READ) &&
+	    !(oparms->desired_access & GENERIC_EXECUTE) &&
+	    !(oparms->desired_access & GENERIC_ALL) &&
 	    !(oparms->desired_access & MAXIMUM_ALLOWED)) {
 		oparms->desired_access |= FILE_READ_ATTRIBUTES;
 		retry_without_read_attributes = true;
-- 
2.20.1