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authorJeff Mahoney <jeffm@suse.com>2016-07-05 17:32:30 -0400
committerTyler Hicks <tyhicks@canonical.com>2016-07-08 10:35:28 -0500
commitf0fe970df3838c202ef6c07a4c2b36838ef0a88b (patch)
treef9556752b553050c87aef3172147f94e242778a9
parent78c4e172412de5d0456dc00d2b34050aa0b683b5 (diff)
downloadlinux-sh-f0fe970df3838c202ef6c07a4c2b36838ef0a88b.tar.gz
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 <jeffm@suse.com> Cc: stable@vger.kernel.org [tyhicks: clean up f_op check by using ecryptfs_file_to_lower()] Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
-rw-r--r--fs/ecryptfs/file.c15
1 files changed, 14 insertions, 1 deletions
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,