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ecryptfs: don't allow mmap when the lower fs doesn't support it

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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>
This commit is contained in:
Jeff Mahoney 2016-07-05 17:32:30 -04:00 committed by Tyler Hicks
parent 78c4e17241
commit f0fe970df3
1 changed files with 14 additions and 1 deletions
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15
fs/ecryptfs/file.c
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@ -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,