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f70ee5ec8f
In the loop in scatterwalk_copychunks(), if walk->offset is zero,
then scatterwalk_pagedone rounds that up to the nearest page boundary:
walk->offset += PAGE_SIZE - 1;
walk->offset &= PAGE_MASK;
which is a no-op in this case, so we don't advance to the next element
of the scatterlist array:
if (walk->offset >= walk->sg->offset + walk->sg->length)
scatterwalk_start(walk, sg_next(walk->sg));
and we end up copying the same data twice.
It appears that other callers of scatterwalk_{page}done first advance
walk->offset, so I believe that's the correct thing to do here.
This caused a bug in NFS when run with krb5p security, which would
cause some writes to fail with permissions errors--for example, writes
of less than 8 bytes (the des blocksize) at the start of a file.
A git-bisect shows the bug was originally introduced by
5c64097aa0, first in 2.6.19-rc1.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
105 lines
2.4 KiB
C
105 lines
2.4 KiB
C
/*
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* Cryptographic API.
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*
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* Cipher operations.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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* 2002 Adam J. Richter <adam@yggdrasil.com>
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* 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/scatterlist.h>
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#include "internal.h"
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#include "scatterwalk.h"
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enum km_type crypto_km_types[] = {
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KM_USER0,
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KM_USER1,
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KM_SOFTIRQ0,
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KM_SOFTIRQ1,
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};
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EXPORT_SYMBOL_GPL(crypto_km_types);
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static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
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{
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void *src = out ? buf : sgdata;
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void *dst = out ? sgdata : buf;
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memcpy(dst, src, nbytes);
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}
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void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
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{
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walk->sg = sg;
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BUG_ON(!sg->length);
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walk->offset = sg->offset;
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}
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EXPORT_SYMBOL_GPL(scatterwalk_start);
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void *scatterwalk_map(struct scatter_walk *walk, int out)
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{
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return crypto_kmap(scatterwalk_page(walk), out) +
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offset_in_page(walk->offset);
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}
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EXPORT_SYMBOL_GPL(scatterwalk_map);
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static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
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unsigned int more)
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{
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if (out)
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flush_dcache_page(scatterwalk_page(walk));
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if (more) {
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walk->offset += PAGE_SIZE - 1;
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walk->offset &= PAGE_MASK;
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if (walk->offset >= walk->sg->offset + walk->sg->length)
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scatterwalk_start(walk, sg_next(walk->sg));
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}
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}
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void scatterwalk_done(struct scatter_walk *walk, int out, int more)
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{
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if (!offset_in_page(walk->offset) || !more)
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scatterwalk_pagedone(walk, out, more);
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}
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EXPORT_SYMBOL_GPL(scatterwalk_done);
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void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
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size_t nbytes, int out)
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{
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for (;;) {
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unsigned int len_this_page = scatterwalk_pagelen(walk);
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u8 *vaddr;
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if (len_this_page > nbytes)
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len_this_page = nbytes;
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vaddr = scatterwalk_map(walk, out);
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memcpy_dir(buf, vaddr, len_this_page, out);
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scatterwalk_unmap(vaddr, out);
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scatterwalk_advance(walk, nbytes);
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if (nbytes == len_this_page)
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break;
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buf += len_this_page;
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nbytes -= len_this_page;
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scatterwalk_pagedone(walk, out, 1);
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}
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}
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EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
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