cifs: Fix and improve cifs_is_path_accessible() function

Do not call SMBQueryInformation() command for path with SMB wildcard
characters on non-UNICODE connection because server expands wildcards.
Function cifs_is_path_accessible() needs to check if the real path exists
and must not expand wildcard characters.

Do not dynamically allocate memory for small FILE_ALL_INFO structure and
instead allocate it on the stack. This structure is allocated on stack by
all other functions.

When CAP_NT_SMBS was not negotiated then do not issue CIFSSMBQPathInfo()
command. This command returns failure by non-NT Win9x SMB servers, so there
is no need try it. The purpose of cifs_is_path_accessible() function is
just to check if the path is accessible, so SMBQueryInformation() for old
servers is enough.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index f72879af12c978b8531eee9eea3f9647e6198369..dc5a8c1da623166c5be6e988d8ba133b8f1aea2e 100644 (file)
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -505,21 +505,27 @@ static int
 cifs_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
                        struct cifs_sb_info *cifs_sb, const char *full_path)
 {
-       int rc;
-       FILE_ALL_INFO *file_info;
+       int rc = -EOPNOTSUPP;
+       FILE_ALL_INFO file_info;
 
-       file_info = kmalloc_obj(FILE_ALL_INFO);
-       if (file_info == NULL)
-               return -ENOMEM;
+       if (tcon->ses->capabilities & CAP_NT_SMBS)
+               rc = CIFSSMBQPathInfo(xid, tcon, full_path, &file_info,
+                                     0 /* not legacy */, cifs_sb->local_nls,
+                                     cifs_remap(cifs_sb));
 
-       rc = CIFSSMBQPathInfo(xid, tcon, full_path, file_info,
-                             0 /* not legacy */, cifs_sb->local_nls,
-                             cifs_remap(cifs_sb));
+       /*
+        * Non-UNICODE variant of fallback functions below expands wildcards,
+        * so they cannot be used for querying paths with wildcard characters.
+        * Therefore for such paths returns -ENOENT as they cannot exist.
+        */
+       if ((rc == -EOPNOTSUPP || rc == -EINVAL) &&
+           !(tcon->ses->capabilities & CAP_UNICODE) &&
+           strpbrk(full_path, "*?\"><"))
+               rc = -ENOENT;
 
        if (rc == -EOPNOTSUPP || rc == -EINVAL)
-               rc = SMBQueryInformation(xid, tcon, full_path, file_info,
+               rc = SMBQueryInformation(xid, tcon, full_path, &file_info,
                                cifs_sb->local_nls, cifs_remap(cifs_sb));
-       kfree(file_info);
        return rc;
 }