lkml.org 
[lkml]   [2012]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[ 136/187] eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------

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);
@@ -269,8 +273,16 @@ 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);
@@ -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);



\
 
 \ /
  Last update: 2012-07-13 02:02    [W:0.404 / U:0.124 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site