Patch "eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files" has been added to the 3.0-stable tree

Patch "eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files" has been added to the 3.0-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files

to the 3.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ecryptfs-gracefully-refuse-miscdev-file-ops-on-inherited-passed-files.patch
and it can be found in the queue-3.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8dc6780587c99286c0d3de747a2946a76989414a Mon Sep 17 00:00:00 2001
From: Tyler Hicks <tyhicks@canonical.com>
Date: Mon, 11 Jun 2012 09:24:11 -0700
Subject: eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files

From: Tyler Hicks <tyhicks@canonical.com>

commit 8dc6780587c99286c0d3de747a2946a76989414a upstream.

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 <tyhicks@canonical.com>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ecryptfs/miscdev.c |   23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -49,7 +49,10 @@ ecryptfs_miscdev_poll(struct file *file,
 	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 *inod
 		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 *i
 
 	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);
@@ -246,8 +250,16 @@ ecryptfs_miscdev_read(struct file *file,
 	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);
@@ -284,9 +296,6 @@ 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);


Patches currently in stable-queue which might be from tyhicks@canonical.com are

queue-3.0/ecryptfs-properly-check-for-o_rdonly-flag-before-doing-privileged-open.patch
queue-3.0/ecryptfs-fix-lockdep-warning-in-miscdev-operations.patch
queue-3.0/ecryptfs-gracefully-refuse-miscdev-file-ops-on-inherited-passed-files.patch