linux/drivers/crypto/omap-crypto.c
Tero Kristo 7e34e0bbc6 crypto: omap-crypto - fix userspace copied buffer access
In case buffers are copied from userspace, directly accessing the page
will most likely fail because it hasn't been mapped into the kernel
memory space. Fix the issue by forcing a kmap / kunmap within the
cleanup functionality.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-06-04 22:03:40 +10:00

227 lines
4.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* OMAP Crypto driver common support routines.
*
* Copyright (c) 2017 Texas Instruments Incorporated
* Tero Kristo <t-kristo@ti.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/scatterlist.h>
#include <crypto/scatterwalk.h>
#include "omap-crypto.h"
static int omap_crypto_copy_sg_lists(int total, int bs,
struct scatterlist **sg,
struct scatterlist *new_sg, u16 flags)
{
int n = sg_nents(*sg);
struct scatterlist *tmp;
if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY)) {
new_sg = kmalloc_array(n, sizeof(*sg), GFP_KERNEL);
if (!new_sg)
return -ENOMEM;
sg_init_table(new_sg, n);
}
tmp = new_sg;
while (*sg && total) {
int len = (*sg)->length;
if (total < len)
len = total;
if (len > 0) {
total -= len;
sg_set_page(tmp, sg_page(*sg), len, (*sg)->offset);
if (total <= 0)
sg_mark_end(tmp);
tmp = sg_next(tmp);
}
*sg = sg_next(*sg);
}
*sg = new_sg;
return 0;
}
static int omap_crypto_copy_sgs(int total, int bs, struct scatterlist **sg,
struct scatterlist *new_sg, u16 flags)
{
void *buf;
int pages;
int new_len;
new_len = ALIGN(total, bs);
pages = get_order(new_len);
buf = (void *)__get_free_pages(GFP_ATOMIC, pages);
if (!buf) {
pr_err("%s: Couldn't allocate pages for unaligned cases.\n",
__func__);
return -ENOMEM;
}
if (flags & OMAP_CRYPTO_COPY_DATA) {
scatterwalk_map_and_copy(buf, *sg, 0, total, 0);
if (flags & OMAP_CRYPTO_ZERO_BUF)
memset(buf + total, 0, new_len - total);
}
if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY))
sg_init_table(new_sg, 1);
sg_set_buf(new_sg, buf, new_len);
*sg = new_sg;
return 0;
}
static int omap_crypto_check_sg(struct scatterlist *sg, int total, int bs,
u16 flags)
{
int len = 0;
int num_sg = 0;
if (!IS_ALIGNED(total, bs))
return OMAP_CRYPTO_NOT_ALIGNED;
while (sg) {
num_sg++;
if (!IS_ALIGNED(sg->offset, 4))
return OMAP_CRYPTO_NOT_ALIGNED;
if (!IS_ALIGNED(sg->length, bs))
return OMAP_CRYPTO_NOT_ALIGNED;
#ifdef CONFIG_ZONE_DMA
if (page_zonenum(sg_page(sg)) != ZONE_DMA)
return OMAP_CRYPTO_NOT_ALIGNED;
#endif
len += sg->length;
sg = sg_next(sg);
if (len >= total)
break;
}
if ((flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY) && num_sg > 1)
return OMAP_CRYPTO_NOT_ALIGNED;
if (len != total)
return OMAP_CRYPTO_BAD_DATA_LENGTH;
return 0;
}
int omap_crypto_align_sg(struct scatterlist **sg, int total, int bs,
struct scatterlist *new_sg, u16 flags,
u8 flags_shift, unsigned long *dd_flags)
{
int ret;
*dd_flags &= ~(OMAP_CRYPTO_COPY_MASK << flags_shift);
if (flags & OMAP_CRYPTO_FORCE_COPY)
ret = OMAP_CRYPTO_NOT_ALIGNED;
else
ret = omap_crypto_check_sg(*sg, total, bs, flags);
if (ret == OMAP_CRYPTO_NOT_ALIGNED) {
ret = omap_crypto_copy_sgs(total, bs, sg, new_sg, flags);
if (ret)
return ret;
*dd_flags |= OMAP_CRYPTO_DATA_COPIED << flags_shift;
} else if (ret == OMAP_CRYPTO_BAD_DATA_LENGTH) {
ret = omap_crypto_copy_sg_lists(total, bs, sg, new_sg, flags);
if (ret)
return ret;
if (!(flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY))
*dd_flags |= OMAP_CRYPTO_SG_COPIED << flags_shift;
} else if (flags & OMAP_CRYPTO_FORCE_SINGLE_ENTRY) {
sg_set_buf(new_sg, sg_virt(*sg), (*sg)->length);
}
return 0;
}
EXPORT_SYMBOL_GPL(omap_crypto_align_sg);
static void omap_crypto_copy_data(struct scatterlist *src,
struct scatterlist *dst,
int offset, int len)
{
int amt;
void *srcb, *dstb;
int srco = 0, dsto = offset;
while (src && dst && len) {
if (srco >= src->length) {
srco -= src->length;
src = sg_next(src);
continue;
}
if (dsto >= dst->length) {
dsto -= dst->length;
dst = sg_next(dst);
continue;
}
amt = min(src->length - srco, dst->length - dsto);
amt = min(len, amt);
srcb = kmap_atomic(sg_page(src)) + srco + src->offset;
dstb = kmap_atomic(sg_page(dst)) + dsto + dst->offset;
memcpy(dstb, srcb, amt);
if (!PageSlab(sg_page(dst)))
flush_kernel_dcache_page(sg_page(dst));
kunmap_atomic(srcb);
kunmap_atomic(dstb);
srco += amt;
dsto += amt;
len -= amt;
}
}
void omap_crypto_cleanup(struct scatterlist *sg, struct scatterlist *orig,
int offset, int len, u8 flags_shift,
unsigned long flags)
{
void *buf;
int pages;
flags >>= flags_shift;
flags &= OMAP_CRYPTO_COPY_MASK;
if (!flags)
return;
buf = sg_virt(sg);
pages = get_order(len);
if (orig && (flags & OMAP_CRYPTO_COPY_MASK))
omap_crypto_copy_data(sg, orig, offset, len);
if (flags & OMAP_CRYPTO_DATA_COPIED)
free_pages((unsigned long)buf, pages);
else if (flags & OMAP_CRYPTO_SG_COPIED)
kfree(sg);
}
EXPORT_SYMBOL_GPL(omap_crypto_cleanup);
MODULE_DESCRIPTION("OMAP crypto support library.");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");