linux/crypto/lrw.c
Eric Biggers 9df0eb180c crypto: xts,lrw - fix out-of-bounds write after kmalloc failure
In the generic XTS and LRW algorithms, for input data > 128 bytes, a
temporary buffer is allocated to hold the values to be XOR'ed with the
data before and after encryption or decryption.  If the allocation
fails, the fixed-size buffer embedded in the request buffer is meant to
be used as a fallback --- resulting in more calls to the ECB algorithm,
but still producing the correct result.  However, we weren't correctly
limiting subreq->cryptlen in this case, resulting in pre_crypt()
overrunning the embedded buffer.  Fix this by setting subreq->cryptlen
correctly.

Fixes: f1c131b454 ("crypto: xts - Convert to skcipher")
Fixes: 700cb3f5fe ("crypto: lrw - Convert to skcipher")
Cc: stable@vger.kernel.org # v4.10+
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-03-24 21:51:34 +08:00

660 lines
15 KiB
C

/* LRW: as defined by Cyril Guyot in
* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
*
* Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
*
* Based on ecb.c
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*/
/* This implementation is checked against the test vectors in the above
* document and by a test vector provided by Ken Buchanan at
* http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
*
* The test vectors are included in the testing module tcrypt.[ch] */
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/lrw.h>
#define LRW_BUFFER_SIZE 128u
struct priv {
struct crypto_skcipher *child;
struct lrw_table_ctx table;
};
struct rctx {
be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
be128 t;
be128 *ext;
struct scatterlist srcbuf[2];
struct scatterlist dstbuf[2];
struct scatterlist *src;
struct scatterlist *dst;
unsigned int left;
struct skcipher_request subreq;
};
static inline void setbit128_bbe(void *b, int bit)
{
__set_bit(bit ^ (0x80 -
#ifdef __BIG_ENDIAN
BITS_PER_LONG
#else
BITS_PER_BYTE
#endif
), b);
}
int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
{
be128 tmp = { 0 };
int i;
if (ctx->table)
gf128mul_free_64k(ctx->table);
/* initialize multiplication table for Key2 */
ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
if (!ctx->table)
return -ENOMEM;
/* initialize optimization table */
for (i = 0; i < 128; i++) {
setbit128_bbe(&tmp, i);
ctx->mulinc[i] = tmp;
gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
}
return 0;
}
EXPORT_SYMBOL_GPL(lrw_init_table);
void lrw_free_table(struct lrw_table_ctx *ctx)
{
if (ctx->table)
gf128mul_free_64k(ctx->table);
}
EXPORT_SYMBOL_GPL(lrw_free_table);
static int setkey(struct crypto_skcipher *parent, const u8 *key,
unsigned int keylen)
{
struct priv *ctx = crypto_skcipher_ctx(parent);
struct crypto_skcipher *child = ctx->child;
int err, bsize = LRW_BLOCK_SIZE;
const u8 *tweak = key + keylen - bsize;
crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_skcipher_setkey(child, key, keylen - bsize);
crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
if (err)
return err;
return lrw_init_table(&ctx->table, tweak);
}
static inline void inc(be128 *iv)
{
be64_add_cpu(&iv->b, 1);
if (!iv->b)
be64_add_cpu(&iv->a, 1);
}
/* this returns the number of consequative 1 bits starting
* from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
static inline int get_index128(be128 *block)
{
int x;
__be32 *p = (__be32 *) block;
for (p += 3, x = 0; x < 128; p--, x += 32) {
u32 val = be32_to_cpup(p);
if (!~val)
continue;
return x + ffz(val);
}
return x;
}
static int post_crypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
be128 *buf = rctx->ext ?: rctx->buf;
struct skcipher_request *subreq;
const int bs = LRW_BLOCK_SIZE;
struct skcipher_walk w;
struct scatterlist *sg;
unsigned offset;
int err;
subreq = &rctx->subreq;
err = skcipher_walk_virt(&w, subreq, false);
while (w.nbytes) {
unsigned int avail = w.nbytes;
be128 *wdst;
wdst = w.dst.virt.addr;
do {
be128_xor(wdst, buf++, wdst);
wdst++;
} while ((avail -= bs) >= bs);
err = skcipher_walk_done(&w, avail);
}
rctx->left -= subreq->cryptlen;
if (err || !rctx->left)
goto out;
rctx->dst = rctx->dstbuf;
scatterwalk_done(&w.out, 0, 1);
sg = w.out.sg;
offset = w.out.offset;
if (rctx->dst != sg) {
rctx->dst[0] = *sg;
sg_unmark_end(rctx->dst);
scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
}
rctx->dst[0].length -= offset - sg->offset;
rctx->dst[0].offset = offset;
out:
return err;
}
static int pre_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct rctx *rctx = skcipher_request_ctx(req);
struct priv *ctx = crypto_skcipher_ctx(tfm);
be128 *buf = rctx->ext ?: rctx->buf;
struct skcipher_request *subreq;
const int bs = LRW_BLOCK_SIZE;
struct skcipher_walk w;
struct scatterlist *sg;
unsigned cryptlen;
unsigned offset;
be128 *iv;
bool more;
int err;
subreq = &rctx->subreq;
skcipher_request_set_tfm(subreq, tfm);
cryptlen = subreq->cryptlen;
more = rctx->left > cryptlen;
if (!more)
cryptlen = rctx->left;
skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
cryptlen, req->iv);
err = skcipher_walk_virt(&w, subreq, false);
iv = w.iv;
while (w.nbytes) {
unsigned int avail = w.nbytes;
be128 *wsrc;
be128 *wdst;
wsrc = w.src.virt.addr;
wdst = w.dst.virt.addr;
do {
*buf++ = rctx->t;
be128_xor(wdst++, &rctx->t, wsrc++);
/* T <- I*Key2, using the optimization
* discussed in the specification */
be128_xor(&rctx->t, &rctx->t,
&ctx->table.mulinc[get_index128(iv)]);
inc(iv);
} while ((avail -= bs) >= bs);
err = skcipher_walk_done(&w, avail);
}
skcipher_request_set_tfm(subreq, ctx->child);
skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
cryptlen, NULL);
if (err || !more)
goto out;
rctx->src = rctx->srcbuf;
scatterwalk_done(&w.in, 0, 1);
sg = w.in.sg;
offset = w.in.offset;
if (rctx->src != sg) {
rctx->src[0] = *sg;
sg_unmark_end(rctx->src);
scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
}
rctx->src[0].length -= offset - sg->offset;
rctx->src[0].offset = offset;
out:
return err;
}
static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
{
struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq;
gfp_t gfp;
subreq = &rctx->subreq;
skcipher_request_set_callback(subreq, req->base.flags, done, req);
gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
GFP_ATOMIC;
rctx->ext = NULL;
subreq->cryptlen = LRW_BUFFER_SIZE;
if (req->cryptlen > LRW_BUFFER_SIZE) {
unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
rctx->ext = kmalloc(n, gfp);
if (rctx->ext)
subreq->cryptlen = n;
}
rctx->src = req->src;
rctx->dst = req->dst;
rctx->left = req->cryptlen;
/* calculate first value of T */
memcpy(&rctx->t, req->iv, sizeof(rctx->t));
/* T <- I*Key2 */
gf128mul_64k_bbe(&rctx->t, ctx->table.table);
return 0;
}
static void exit_crypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
rctx->left = 0;
if (rctx->ext)
kfree(rctx->ext);
}
static int do_encrypt(struct skcipher_request *req, int err)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq;
subreq = &rctx->subreq;
while (!err && rctx->left) {
err = pre_crypt(req) ?:
crypto_skcipher_encrypt(subreq) ?:
post_crypt(req);
if (err == -EINPROGRESS ||
(err == -EBUSY &&
req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
return err;
}
exit_crypt(req);
return err;
}
static void encrypt_done(struct crypto_async_request *areq, int err)
{
struct skcipher_request *req = areq->data;
struct skcipher_request *subreq;
struct rctx *rctx;
rctx = skcipher_request_ctx(req);
subreq = &rctx->subreq;
subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
err = do_encrypt(req, err ?: post_crypt(req));
if (rctx->left)
return;
skcipher_request_complete(req, err);
}
static int encrypt(struct skcipher_request *req)
{
return do_encrypt(req, init_crypt(req, encrypt_done));
}
static int do_decrypt(struct skcipher_request *req, int err)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq;
subreq = &rctx->subreq;
while (!err && rctx->left) {
err = pre_crypt(req) ?:
crypto_skcipher_decrypt(subreq) ?:
post_crypt(req);
if (err == -EINPROGRESS ||
(err == -EBUSY &&
req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
return err;
}
exit_crypt(req);
return err;
}
static void decrypt_done(struct crypto_async_request *areq, int err)
{
struct skcipher_request *req = areq->data;
struct skcipher_request *subreq;
struct rctx *rctx;
rctx = skcipher_request_ctx(req);
subreq = &rctx->subreq;
subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
err = do_decrypt(req, err ?: post_crypt(req));
if (rctx->left)
return;
skcipher_request_complete(req, err);
}
static int decrypt(struct skcipher_request *req)
{
return do_decrypt(req, init_crypt(req, decrypt_done));
}
int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
struct scatterlist *ssrc, unsigned int nbytes,
struct lrw_crypt_req *req)
{
const unsigned int bsize = LRW_BLOCK_SIZE;
const unsigned int max_blks = req->tbuflen / bsize;
struct lrw_table_ctx *ctx = req->table_ctx;
struct blkcipher_walk walk;
unsigned int nblocks;
be128 *iv, *src, *dst, *t;
be128 *t_buf = req->tbuf;
int err, i;
BUG_ON(max_blks < 1);
blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
err = blkcipher_walk_virt(desc, &walk);
nbytes = walk.nbytes;
if (!nbytes)
return err;
nblocks = min(walk.nbytes / bsize, max_blks);
src = (be128 *)walk.src.virt.addr;
dst = (be128 *)walk.dst.virt.addr;
/* calculate first value of T */
iv = (be128 *)walk.iv;
t_buf[0] = *iv;
/* T <- I*Key2 */
gf128mul_64k_bbe(&t_buf[0], ctx->table);
i = 0;
goto first;
for (;;) {
do {
for (i = 0; i < nblocks; i++) {
/* T <- I*Key2, using the optimization
* discussed in the specification */
be128_xor(&t_buf[i], t,
&ctx->mulinc[get_index128(iv)]);
inc(iv);
first:
t = &t_buf[i];
/* PP <- T xor P */
be128_xor(dst + i, t, src + i);
}
/* CC <- E(Key2,PP) */
req->crypt_fn(req->crypt_ctx, (u8 *)dst,
nblocks * bsize);
/* C <- T xor CC */
for (i = 0; i < nblocks; i++)
be128_xor(dst + i, dst + i, &t_buf[i]);
src += nblocks;
dst += nblocks;
nbytes -= nblocks * bsize;
nblocks = min(nbytes / bsize, max_blks);
} while (nblocks > 0);
err = blkcipher_walk_done(desc, &walk, nbytes);
nbytes = walk.nbytes;
if (!nbytes)
break;
nblocks = min(nbytes / bsize, max_blks);
src = (be128 *)walk.src.virt.addr;
dst = (be128 *)walk.dst.virt.addr;
}
return err;
}
EXPORT_SYMBOL_GPL(lrw_crypt);
static int init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
struct priv *ctx = crypto_skcipher_ctx(tfm);
struct crypto_skcipher *cipher;
cipher = crypto_spawn_skcipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
sizeof(struct rctx));
return 0;
}
static void exit_tfm(struct crypto_skcipher *tfm)
{
struct priv *ctx = crypto_skcipher_ctx(tfm);
lrw_free_table(&ctx->table);
crypto_free_skcipher(ctx->child);
}
static void free(struct skcipher_instance *inst)
{
crypto_drop_skcipher(skcipher_instance_ctx(inst));
kfree(inst);
}
static int create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct crypto_skcipher_spawn *spawn;
struct skcipher_instance *inst;
struct crypto_attr_type *algt;
struct skcipher_alg *alg;
const char *cipher_name;
char ecb_name[CRYPTO_MAX_ALG_NAME];
int err;
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
return PTR_ERR(algt);
if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
return -EINVAL;
cipher_name = crypto_attr_alg_name(tb[1]);
if (IS_ERR(cipher_name))
return PTR_ERR(cipher_name);
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
spawn = skcipher_instance_ctx(inst);
crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
err = crypto_grab_skcipher(spawn, cipher_name, 0,
crypto_requires_sync(algt->type,
algt->mask));
if (err == -ENOENT) {
err = -ENAMETOOLONG;
if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
cipher_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
err = crypto_grab_skcipher(spawn, ecb_name, 0,
crypto_requires_sync(algt->type,
algt->mask));
}
if (err)
goto err_free_inst;
alg = crypto_skcipher_spawn_alg(spawn);
err = -EINVAL;
if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
goto err_drop_spawn;
if (crypto_skcipher_alg_ivsize(alg))
goto err_drop_spawn;
err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
&alg->base);
if (err)
goto err_drop_spawn;
err = -EINVAL;
cipher_name = alg->base.cra_name;
/* Alas we screwed up the naming so we have to mangle the
* cipher name.
*/
if (!strncmp(cipher_name, "ecb(", 4)) {
unsigned len;
len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
if (len < 2 || len >= sizeof(ecb_name))
goto err_drop_spawn;
if (ecb_name[len - 1] != ')')
goto err_drop_spawn;
ecb_name[len - 1] = 0;
if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
"lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME)
return -ENAMETOOLONG;
}
inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
inst->alg.base.cra_priority = alg->base.cra_priority;
inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
(__alignof__(u64) - 1);
inst->alg.ivsize = LRW_BLOCK_SIZE;
inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
LRW_BLOCK_SIZE;
inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
LRW_BLOCK_SIZE;
inst->alg.base.cra_ctxsize = sizeof(struct priv);
inst->alg.init = init_tfm;
inst->alg.exit = exit_tfm;
inst->alg.setkey = setkey;
inst->alg.encrypt = encrypt;
inst->alg.decrypt = decrypt;
inst->free = free;
err = skcipher_register_instance(tmpl, inst);
if (err)
goto err_drop_spawn;
out:
return err;
err_drop_spawn:
crypto_drop_skcipher(spawn);
err_free_inst:
kfree(inst);
goto out;
}
static struct crypto_template crypto_tmpl = {
.name = "lrw",
.create = create,
.module = THIS_MODULE,
};
static int __init crypto_module_init(void)
{
return crypto_register_template(&crypto_tmpl);
}
static void __exit crypto_module_exit(void)
{
crypto_unregister_template(&crypto_tmpl);
}
module_init(crypto_module_init);
module_exit(crypto_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");
MODULE_ALIAS_CRYPTO("lrw");