eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files
authorTyler Hicks <tyhicks@canonical.com>
Mon, 11 Jun 2012 16:24:11 +0000 (09:24 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 16 Jul 2012 16:04:26 +0000 (09:04 -0700)
commit6dfa530c0b33f1ccd2d8b103a2dea6ec559de66c
treedf4f53ead7bb20b2ca77c173cd5ed8eb5d155762
parent6d442d8f7e1a6920aad3d3f3ea544f6f8e6898b8
eCryptfs: Gracefully refuse miscdev file ops on inherited/passed files

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