diff --git a/fs/fhandle.c b/fs/fhandle.c index 68a7d2861c58..a907ddfac4d5 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -207,6 +207,14 @@ static int vfs_dentry_acceptable(void *context, struct dentry *dentry) if (!ctx->flags) return 1; + /* + * Verify that the decoded dentry itself has a valid id mapping. + * In case the decoded dentry is the mountfd root itself, this + * verifies that the mountfd inode itself has a valid id mapping. + */ + if (!privileged_wrt_inode_uidgid(user_ns, idmap, d_inode(dentry))) + return 0; + /* * It's racy as we're not taking rename_lock but we're able to ignore * permissions and we just need an approximation whether we were able