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virtiofsd: Don't allow empty paths in lookup_name()

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When passed an empty filename, lookup_name() returns the inode of
the parent directory, unless the parent is the root in which case
the st_dev doesn't match and lo_find() returns NULL. This is
because lookup_name() passes AT_EMPTY_PATH down to fstatat() or
statx().

This behavior doesn't quite make sense because users of lookup_name()
then pass the name to unlinkat(), renameat() or renameat2(), all of
which will always fail on empty names.

Drop AT_EMPTY_PATH from the flags in lookup_name() so that it has
the consistent behavior of "returning an existing child inode or
NULL" for all directories.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210312141003.819108-2-groug@kaod.org>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Greg Kurz 2021-03-12 15:10:01 +01:00 committed by Dr. David Alan Gilbert
parent 28d1ad0ea4
commit 20afcc23b3
1 changed files with 1 additions and 2 deletions
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3
tools/virtiofsd/passthrough_ll.c
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@ -1330,8 +1330,7 @@ static struct lo_inode *lookup_name(fuse_req_t req, fuse_ino_t parent,
return NULL;
}
res = do_statx(lo, dir->fd, name, &attr,
AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW, &mnt_id);
res = do_statx(lo, dir->fd, name, &attr, AT_SYMLINK_NOFOLLOW, &mnt_id);
lo_inode_put(lo, &dir);
if (res == -1) {
return NULL;