From f0fe970df3838c202ef6c07a4c2b36838ef0a88b 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 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 --- 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 53d0141b9c20..ca4e83750214 100644 --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -169,6 +169,19 @@ 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 specifying file to open @@ -403,7 +416,7 @@ 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, -- 2.20.1