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 <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> Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
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@ -230,6 +230,19 @@ out:
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return rc;
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}
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static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct file *lower_file = ecryptfs_file_to_lower(file);
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/*
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* Don't allow mmap on top of file systems that don't support it
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* natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
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* allows recursive mounting, this will need to be extended.
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*/
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if (!lower_file->f_op->mmap)
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return -ENODEV;
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return generic_file_mmap(file, vma);
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}
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/**
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* ecryptfs_open
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* @inode: inode speciying file to open
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@ -551,7 +564,7 @@ const struct file_operations ecryptfs_main_fops = {
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#ifdef CONFIG_COMPAT
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.compat_ioctl = ecryptfs_compat_ioctl,
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#endif
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.mmap = generic_file_mmap,
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.mmap = ecryptfs_mmap,
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.open = ecryptfs_open,
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.flush = ecryptfs_flush,
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.release = ecryptfs_release,
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