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SubjectRe: [PATCH 3/3] eCryptfs: Encrypted passthrough
On Tue, 9 Jan 2007 16:23:37 -0600
Michael Halcrow <mhalcrow@us.ibm.com> wrote:

> + page_virt = (char *)kmap(page);

Do we _have_ to use kmap here? It's slow and theoretically deadlocky.
kmap_atomic() is much preferred.

Can the other kmap() calls in ecryptfs be converted?

We'd actually like to remove kmap() one day. Not much chance of that, but
it's an objective.

> + if (!page_virt) {
> + rc = -ENOMEM;
> + printk(KERN_ERR "Error mapping page\n");
> + goto out;
> + }
> + memset(page_virt, 0, PAGE_CACHE_SIZE);
> + if (page->index == 0) {
> + rc = ecryptfs_read_xattr_region(
> + page_virt, file->f_path.dentry);

Are we assured that ecryptfs_read_xattr_region() cannot overrun the page?

> + set_header_info(page_virt, crypt_stat);
> + }

The kernel must always run flush_dcache_page() after modifying a pagecache
page by hand. Please review all of ecryptfs for this.


> + kunmap(page);
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