From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753883Ab2FMAGn (ORCPT ); Tue, 12 Jun 2012 20:06:43 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:54050 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753261Ab2FMAF7 (ORCPT ); Tue, 12 Jun 2012 20:05:59 -0400 From: Tyler Hicks To: ecryptfs@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sasha Levin Subject: [PATCH 1/3] eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files Date: Tue, 12 Jun 2012 17:05:38 -0700 Message-Id: <1339545940-11736-2-git-send-email-tyhicks@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1339545940-11736-1-git-send-email-tyhicks@canonical.com> References: <1338061161.4284.16.camel@lappy> <1339545940-11736-1-git-send-email-tyhicks@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org File operations on /dev/ecryptfs would BUG() when the operations were performed by processes other than the process that originally opened the file. This could happen with open files inherited after fork() or file descriptors passed through IPC mechanisms. Rather than calling BUG(), an error code can be safely returned in most situations. In ecryptfs_miscdev_release(), eCryptfs still needs to handle the release even if the last file reference is being held by a process that didn't originally open the file. ecryptfs_find_daemon_by_euid() will not be successful, so a pointer to the daemon is stored in the file's private_data. The private_data pointer is initialized when the miscdev file is opened and only used when the file is released. https://launchpad.net/bugs/994247 Signed-off-by: Tyler Hicks Reported-by: Sasha Levin Cc: Sasha Levin --- fs/ecryptfs/miscdev.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c index 3a06f40..2cd9c3f 100644 --- a/fs/ecryptfs/miscdev.c +++ b/fs/ecryptfs/miscdev.c @@ -49,7 +49,10 @@ ecryptfs_miscdev_poll(struct file *file, poll_table *pt) mutex_lock(&ecryptfs_daemon_hash_mux); /* TODO: Just use file->private_data? */ rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - BUG_ON(rc || !daemon); + if (rc || !daemon) { + mutex_unlock(&ecryptfs_daemon_hash_mux); + return -EINVAL; + } mutex_lock(&daemon->mux); mutex_unlock(&ecryptfs_daemon_hash_mux); if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { @@ -122,6 +125,7 @@ ecryptfs_miscdev_open(struct inode *inode, struct file *file) goto out_unlock_daemon; } daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN; + file->private_data = daemon; atomic_inc(&ecryptfs_num_miscdev_opens); out_unlock_daemon: mutex_unlock(&daemon->mux); @@ -152,9 +156,9 @@ ecryptfs_miscdev_release(struct inode *inode, struct file *file) mutex_lock(&ecryptfs_daemon_hash_mux); rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - BUG_ON(rc || !daemon); + if (rc || !daemon) + daemon = file->private_data; mutex_lock(&daemon->mux); - BUG_ON(daemon->pid != task_pid(current)); BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN)); daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN; atomic_dec(&ecryptfs_num_miscdev_opens); @@ -269,8 +273,16 @@ ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count, mutex_lock(&ecryptfs_daemon_hash_mux); /* TODO: Just use file->private_data? */ rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns()); - BUG_ON(rc || !daemon); + if (rc || !daemon) { + mutex_unlock(&ecryptfs_daemon_hash_mux); + return -EINVAL; + } mutex_lock(&daemon->mux); + if (task_pid(current) != daemon->pid) { + mutex_unlock(&daemon->mux); + mutex_unlock(&ecryptfs_daemon_hash_mux); + return -EPERM; + } if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) { rc = 0; mutex_unlock(&ecryptfs_daemon_hash_mux); @@ -307,9 +319,6 @@ check_list: * message from the queue; try again */ goto check_list; } - BUG_ON(euid != daemon->euid); - BUG_ON(current_user_ns() != daemon->user_ns); - BUG_ON(task_pid(current) != daemon->pid); msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue, struct ecryptfs_msg_ctx, daemon_out_list); BUG_ON(!msg_ctx); -- 1.7.9.5