linux/crypto/lrw.c
Eric Biggers af5034e8e4 crypto: remove propagation of CRYPTO_TFM_RES_* flags
The CRYPTO_TFM_RES_* flags were apparently meant as a way to make the
->setkey() functions provide more information about errors.  But these
flags weren't actually being used or tested, and in many cases they
weren't being set correctly anyway.  So they've now been removed.

Also, if someone ever actually needs to start better distinguishing
->setkey() errors (which is somewhat unlikely, as this has been unneeded
for a long time), we'd be much better off just defining different return
values, like -EINVAL if the key is invalid for the algorithm vs.
-EKEYREJECTED if the key was rejected by a policy like "no weak keys".
That would be much simpler, less error-prone, and easier to test.

So just remove CRYPTO_TFM_RES_MASK and all the unneeded logic that
propagates these flags around.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-01-09 11:30:53 +08:00

440 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* 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 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>
#define LRW_BLOCK_SIZE 16
struct priv {
struct crypto_skcipher *child;
/*
* optimizes multiplying a random (non incrementing, as at the
* start of a new sector) value with key2, we could also have
* used 4k optimization tables or no optimization at all. In the
* latter case we would have to store key2 here
*/
struct gf128mul_64k *table;
/*
* stores:
* key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
* key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
* key2*{ 0,0,...1,1,1,1,1 }, etc
* needed for optimized multiplication of incrementing values
* with key2
*/
be128 mulinc[128];
};
struct rctx {
be128 t;
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);
}
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;
be128 tmp = { 0 };
int i;
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);
if (err)
return err;
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;
}
/*
* Returns the number of trailing '1' bits in the words of the counter, which is
* represented by 4 32-bit words, arranged from least to most significant.
* At the same time, increments the counter by one.
*
* For example:
*
* u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
* int i = next_index(&counter);
* // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
*/
static int next_index(u32 *counter)
{
int i, res = 0;
for (i = 0; i < 4; i++) {
if (counter[i] + 1 != 0)
return res + ffz(counter[i]++);
counter[i] = 0;
res += 32;
}
/*
* If we get here, then x == 128 and we are incrementing the counter
* from all ones to all zeros. This means we must return index 127, i.e.
* the one corresponding to key2*{ 1,...,1 }.
*/
return 127;
}
/*
* We compute the tweak masks twice (both before and after the ECB encryption or
* decryption) to avoid having to allocate a temporary buffer and/or make
* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
* just doing the next_index() calls again.
*/
static int xor_tweak(struct skcipher_request *req, bool second_pass)
{
const int bs = LRW_BLOCK_SIZE;
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct priv *ctx = crypto_skcipher_ctx(tfm);
struct rctx *rctx = skcipher_request_ctx(req);
be128 t = rctx->t;
struct skcipher_walk w;
__be32 *iv;
u32 counter[4];
int err;
if (second_pass) {
req = &rctx->subreq;
/* set to our TFM to enforce correct alignment: */
skcipher_request_set_tfm(req, tfm);
}
err = skcipher_walk_virt(&w, req, false);
if (err)
return err;
iv = (__be32 *)w.iv;
counter[0] = be32_to_cpu(iv[3]);
counter[1] = be32_to_cpu(iv[2]);
counter[2] = be32_to_cpu(iv[1]);
counter[3] = be32_to_cpu(iv[0]);
while (w.nbytes) {
unsigned int avail = w.nbytes;
be128 *wsrc;
be128 *wdst;
wsrc = w.src.virt.addr;
wdst = w.dst.virt.addr;
do {
be128_xor(wdst++, &t, wsrc++);
/* T <- I*Key2, using the optimization
* discussed in the specification */
be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
} while ((avail -= bs) >= bs);
if (second_pass && w.nbytes == w.total) {
iv[0] = cpu_to_be32(counter[3]);
iv[1] = cpu_to_be32(counter[2]);
iv[2] = cpu_to_be32(counter[1]);
iv[3] = cpu_to_be32(counter[0]);
}
err = skcipher_walk_done(&w, avail);
}
return err;
}
static int xor_tweak_pre(struct skcipher_request *req)
{
return xor_tweak(req, false);
}
static int xor_tweak_post(struct skcipher_request *req)
{
return xor_tweak(req, true);
}
static void crypt_done(struct crypto_async_request *areq, int err)
{
struct skcipher_request *req = areq->data;
if (!err) {
struct rctx *rctx = skcipher_request_ctx(req);
rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
err = xor_tweak_post(req);
}
skcipher_request_complete(req, err);
}
static void init_crypt(struct skcipher_request *req)
{
struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
skcipher_request_set_tfm(subreq, ctx->child);
skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
/* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
skcipher_request_set_crypt(subreq, req->dst, req->dst,
req->cryptlen, req->iv);
/* calculate first value of T */
memcpy(&rctx->t, req->iv, sizeof(rctx->t));
/* T <- I*Key2 */
gf128mul_64k_bbe(&rctx->t, ctx->table);
}
static int encrypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
init_crypt(req);
return xor_tweak_pre(req) ?:
crypto_skcipher_encrypt(subreq) ?:
xor_tweak_post(req);
}
static int decrypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
init_crypt(req);
return xor_tweak_pre(req) ?:
crypto_skcipher_decrypt(subreq) ?:
xor_tweak_post(req);
}
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);
if (ctx->table)
gf128mul_free_64k(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) {
err = -ENAMETOOLONG;
goto err_drop_spawn;
}
} else
goto err_drop_spawn;
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__(be128) - 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);
}
subsys_initcall(crypto_module_init);
module_exit(crypto_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");
MODULE_ALIAS_CRYPTO("lrw");