From 1fb9218645d073f05ac88f7c73d2be103e31b9ea Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Tue, 5 Jul 2016 17:32:30 -0400 Subject: [PATCH] ecryptfs: don't allow mmap when the lower fs doesn't support it There are legitimate reasons to disallow mmap on certain files, notably in sysfs or procfs. We shouldn't emulate mmap support on file systems that don't offer support natively. CVE-2016-1583 Change-Id: I1d7c4a5923d57d5cfcdb3b01ba0300ede45790b5 Signed-off-by: Jeff Mahoney Cc: stable@vger.kernel.org [tyhicks: clean up f_op check by using ecryptfs_file_to_lower()] Signed-off-by: Tyler Hicks Signed-off-by: Kevin F. Haggerty --- fs/ecryptfs/file.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c index 5017d484fcb..aca6214c715 100644 --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -230,6 +230,19 @@ out: return rc; } +static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct file *lower_file = ecryptfs_file_to_lower(file); + /* + * Don't allow mmap on top of file systems that don't support it + * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs + * allows recursive mounting, this will need to be extended. + */ + if (!lower_file->f_op->mmap) + return -ENODEV; + return generic_file_mmap(file, vma); +} + /** * ecryptfs_open * @inode: inode speciying file to open @@ -551,7 +564,7 @@ const struct file_operations ecryptfs_main_fops = { #ifdef CONFIG_COMPAT .compat_ioctl = ecryptfs_compat_ioctl, #endif - .mmap = generic_file_mmap, + .mmap = ecryptfs_mmap, .open = ecryptfs_open, .flush = ecryptfs_flush, .release = ecryptfs_release,