NFSv4: Handle case where the lookup of a directory fails

If the application sets the O_DIRECTORY flag, and tries to open a
regular file, nfs_atomic_open() will punt to doing a regular lookup.
If the server then returns a regular file, we will happily return a
file descriptor with uninitialised open state.

The fix is to return the expected ENOTDIR error in these cases.

Reported-by: Lyu Tao <[email protected]>
Fixes: 0dd2b474d0b6 ("nfs: implement i_op->atomic_open()")
Signed-off-by: Trond Myklebust <[email protected]>
Signed-off-by: Anna Schumaker <[email protected]>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 2884138848f4c647a342a431291f1a1b17260718..408c3bb549b1e13428fa6ea219d62b3a8835b906 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1994,6 +1994,19 @@ out:
 
 no_open:
        res = nfs_lookup(dir, dentry, lookup_flags);
+       if (!res) {
+               inode = d_inode(dentry);
+               if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
+                   !S_ISDIR(inode->i_mode))
+                       res = ERR_PTR(-ENOTDIR);
+       } else if (!IS_ERR(res)) {
+               inode = d_inode(res);
+               if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
+                   !S_ISDIR(inode->i_mode)) {
+                       dput(res);
+                       res = ERR_PTR(-ENOTDIR);
+               }
+       }
        if (switched) {
                d_lookup_done(dentry);
                if (!res)