[PATCH 2/5] cifs: Do not add FILE_READ_ATTRIBUTES when using GENERIC_READ/EXECUTE/ALL

From: Pali Rohár
Date: Tue Dec 31 2024 - 17:36:09 EST


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@xxxxxxxxxx>
---
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