Message-ID: <3F355AB0.6@kolumbus.fi>
Date: Sat, 09 Aug 2003 23:33:52 +0300
From: =?ISO-8859-15?Q?Mika_Penttil=E4?= <mika.penttila@kolumbus.fi>
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To: linux-kernel@vger.kernel.org, linux-net@vger.kernel.org
Subject: cryptoapi incorrect struct page usage
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It seems that cryptoapi usage wrt mm is not safe. At least both ipsec 
and cryptoloop practise these kinds of things :

example from net/xfrm/xfrm_algo.c

int
skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, 
int len)
{
    int start = skb_headlen(skb);
    int i, copy = start - offset;
    int elt = 0;

    if (copy > 0) {
        if (copy > len)
            copy = len;
        sg[elt].page = virt_to_page(skb->data + offset);
        sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
        sg[elt].length = copy;


so unpinned pages are passed to cryptoapi. Nothing prevents these pages 
from being swapped out. Something like get_user_pages() is needed to pin 
these pages for the duration of crypto operations. Comments?

--Mika


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