Mandatory locking is enforced for cached reads, which violates
default posix semantics, and also it is enforced inconsistently.
This affected recent versions of libreoffice, and can be
demonstrated by opening a file twice from the same client,
locking it from handle one and trying to read from it from
handle two (which fails, returning EACCES).
There is already a mount option "forcemandatorylock"
(which defaults to off), so with this change only when the user
intentionally specifies "forcemandatorylock" on mount will we
break posix semantics on read to a locked range (ie we will
only fail in this case, if the user mounts with
"forcemandatorylock").
An earlier patch fixed the write path.
Fixes: 85160e03a79e ("CIFS: Implement caching mechanism for mandatory brlocks")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Pavel Shilovsky <piastryyy@xxxxxxxxx>
Reviewed-by: David Howells <dhowells@xxxxxxxxxx>
Reported-by: abartlet@xxxxxxxxx
Reported-by: Kevin Ottens <kevin.ottens@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 1fc66bcf49eb..f9b302cb8233 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2912,9 +2912,7 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
if (!CIFS_CACHE_READ(cinode))
return netfs_unbuffered_read_iter(iocb, to);
- if (cap_unix(tcon->ses) &&
- (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
- ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) {
+ if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) {
if (iocb->ki_flags & IOCB_DIRECT)
return netfs_unbuffered_read_iter(iocb, to);
return netfs_buffered_read_iter(iocb, to);
