From d9ce899cd99c1b22fb991a5942a1e0e504f6f498 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 commit f0fe970df3838c202ef6c07a4c2b36838ef0a88b upstream. 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 [tyhicks: clean up f_op check by using ecryptfs_file_to_lower()] Signed-off-by: Tyler Hicks Signed-off-by: Ben Hutchings --- 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 0682699519af5..b6c9410f3d049 100644 --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -177,6 +177,19 @@ 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 @@ -374,7 +387,7 @@ 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, -- 2.47.3