From 2b113bf4bdc6a6ae0cd7d177b951e44089907534 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 18 Jul 2017 21:07:43 +0300 Subject: [PATCH] ovl: check for bad and whiteout index on lookup Index should always be of the same file type as origin, except for the case of a whiteout index. A whiteout index should only exist if all lower aliases have been unlinked, which means that finding a lower origin on lookup whose index is a whiteout should be treated as a lookup error. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 229a88ff335c4..8aef2b304b2d2 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -513,6 +513,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, goto out; } + inode = d_inode(index); if (d_is_negative(index)) { if (upper && d_inode(origin)->i_nlink > 1) { pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n", @@ -522,11 +523,22 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, dput(index); index = NULL; - } else if (upper && d_inode(index) != d_inode(upper)) { - inode = d_inode(index); - pr_warn_ratelimited("overlayfs: wrong index found (index ino: %lu, upper ino: %lu).\n", - d_inode(index)->i_ino, - d_inode(upper)->i_ino); + } else if (upper && d_inode(upper) != inode) { + pr_warn_ratelimited("overlayfs: wrong index found (index=%pd2, ino=%lu, upper ino=%lu).\n", + index, inode->i_ino, d_inode(upper)->i_ino); + goto fail; + } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) || + ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) { + /* + * Index should always be of the same file type as origin + * except for the case of a whiteout index. A whiteout + * index should only exist if all lower aliases have been + * unlinked, which means that finding a lower origin on lookup + * whose index is a whiteout should be treated as an error. + */ + pr_warn_ratelimited("overlayfs: bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n", + index, d_inode(index)->i_mode & S_IFMT, + d_inode(origin)->i_mode & S_IFMT); goto fail; } -- 2.39.5