linux-stable/crypto/xts.c
Linus Torvalds dca0ae3900 gcc-10: avoid shadowing standard library 'free()' in crypto
commit 1a263ae60b upstream.

gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.

This results in warnings like:

   crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]

because the crypto layer had its local freeing functions called
'free()'.

Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.

But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.

[ Side note: gcc knowing about 'free()' is in itself not the
  mis-feature: the semantics of 'free()' are special enough that a
  compiler can validly do special things when seeing it.

  So the mis-feature here is that gcc thinks that 'free()' is some
  restricted name, and you can't shadow it as a local static function.

  Making the special 'free()' semantics be a function attribute rather
  than tied to the name would be the much better model ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-20 08:20:29 +02:00

479 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* XTS: as defined in IEEE1619/D16
* http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
*
* Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
*
* Based on ecb.c
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*/
#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/xts.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
struct priv {
struct crypto_skcipher *child;
struct crypto_cipher *tweak;
};
struct xts_instance_ctx {
struct crypto_skcipher_spawn spawn;
char name[CRYPTO_MAX_ALG_NAME];
};
struct rctx {
le128 t;
struct scatterlist *tail;
struct scatterlist sg[2];
struct skcipher_request subreq;
};
static int setkey(struct crypto_skcipher *parent, const u8 *key,
unsigned int keylen)
{
struct priv *ctx = crypto_skcipher_ctx(parent);
struct crypto_skcipher *child;
struct crypto_cipher *tweak;
int err;
err = xts_verify_key(parent, key, keylen);
if (err)
return err;
keylen /= 2;
/* we need two cipher instances: one to compute the initial 'tweak'
* by encrypting the IV (usually the 'plain' iv) and the other
* one to encrypt and decrypt the data */
/* tweak cipher, uses Key2 i.e. the second half of *key */
tweak = ctx->tweak;
crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(tweak, key + keylen, keylen);
crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
CRYPTO_TFM_RES_MASK);
if (err)
return err;
/* data cipher, uses Key1 i.e. the first half of *key */
child = ctx->child;
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);
crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
return err;
}
/*
* 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 gf128mul_x_ble() calls again.
*/
static int xor_tweak(struct skcipher_request *req, bool second_pass, bool enc)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
const int bs = XTS_BLOCK_SIZE;
struct skcipher_walk w;
le128 t = rctx->t;
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);
while (w.nbytes) {
unsigned int avail = w.nbytes;
le128 *wsrc;
le128 *wdst;
wsrc = w.src.virt.addr;
wdst = w.dst.virt.addr;
do {
if (unlikely(cts) &&
w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
if (!enc) {
if (second_pass)
rctx->t = t;
gf128mul_x_ble(&t, &t);
}
le128_xor(wdst, &t, wsrc);
if (enc && second_pass)
gf128mul_x_ble(&rctx->t, &t);
skcipher_walk_done(&w, avail - bs);
return 0;
}
le128_xor(wdst++, &t, wsrc++);
gf128mul_x_ble(&t, &t);
} while ((avail -= bs) >= bs);
err = skcipher_walk_done(&w, avail);
}
return err;
}
static int xor_tweak_pre(struct skcipher_request *req, bool enc)
{
return xor_tweak(req, false, enc);
}
static int xor_tweak_post(struct skcipher_request *req, bool enc)
{
return xor_tweak(req, true, enc);
}
static void cts_done(struct crypto_async_request *areq, int err)
{
struct skcipher_request *req = areq->data;
le128 b;
if (!err) {
struct rctx *rctx = skcipher_request_ctx(req);
scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
le128_xor(&b, &rctx->t, &b);
scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
}
skcipher_request_complete(req, err);
}
static int cts_final(struct skcipher_request *req,
int (*crypt)(struct skcipher_request *req))
{
struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
int tail = req->cryptlen % XTS_BLOCK_SIZE;
le128 b[2];
int err;
rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
offset - XTS_BLOCK_SIZE);
scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
memcpy(b + 1, b, tail);
scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
le128_xor(b, &rctx->t, b);
scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
skcipher_request_set_tfm(subreq, ctx->child);
skcipher_request_set_callback(subreq, req->base.flags, cts_done, req);
skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
XTS_BLOCK_SIZE, NULL);
err = crypt(subreq);
if (err)
return err;
scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
le128_xor(b, &rctx->t, b);
scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
return 0;
}
static void encrypt_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, true);
if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
err = cts_final(req, crypto_skcipher_encrypt);
if (err == -EINPROGRESS)
return;
}
}
skcipher_request_complete(req, err);
}
static void decrypt_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, false);
if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
err = cts_final(req, crypto_skcipher_decrypt);
if (err == -EINPROGRESS)
return;
}
}
skcipher_request_complete(req, err);
}
static int init_crypt(struct skcipher_request *req, crypto_completion_t compl)
{
struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
if (req->cryptlen < XTS_BLOCK_SIZE)
return -EINVAL;
skcipher_request_set_tfm(subreq, ctx->child);
skcipher_request_set_callback(subreq, req->base.flags, compl, req);
skcipher_request_set_crypt(subreq, req->dst, req->dst,
req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);
/* calculate first value of T */
crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
return 0;
}
static int encrypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
int err;
err = init_crypt(req, encrypt_done) ?:
xor_tweak_pre(req, true) ?:
crypto_skcipher_encrypt(subreq) ?:
xor_tweak_post(req, true);
if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
return err;
return cts_final(req, crypto_skcipher_encrypt);
}
static int decrypt(struct skcipher_request *req)
{
struct rctx *rctx = skcipher_request_ctx(req);
struct skcipher_request *subreq = &rctx->subreq;
int err;
err = init_crypt(req, decrypt_done) ?:
xor_tweak_pre(req, false) ?:
crypto_skcipher_decrypt(subreq) ?:
xor_tweak_post(req, false);
if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
return err;
return cts_final(req, crypto_skcipher_decrypt);
}
static int init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
struct priv *ctx = crypto_skcipher_ctx(tfm);
struct crypto_skcipher *child;
struct crypto_cipher *tweak;
child = crypto_spawn_skcipher(&ictx->spawn);
if (IS_ERR(child))
return PTR_ERR(child);
ctx->child = child;
tweak = crypto_alloc_cipher(ictx->name, 0, 0);
if (IS_ERR(tweak)) {
crypto_free_skcipher(ctx->child);
return PTR_ERR(tweak);
}
ctx->tweak = tweak;
crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
sizeof(struct rctx));
return 0;
}
static void exit_tfm(struct crypto_skcipher *tfm)
{
struct priv *ctx = crypto_skcipher_ctx(tfm);
crypto_free_skcipher(ctx->child);
crypto_free_cipher(ctx->tweak);
}
static void free_inst(struct skcipher_instance *inst)
{
crypto_drop_skcipher(skcipher_instance_ctx(inst));
kfree(inst);
}
static int create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct skcipher_instance *inst;
struct crypto_attr_type *algt;
struct xts_instance_ctx *ctx;
struct skcipher_alg *alg;
const char *cipher_name;
u32 mask;
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(*ctx), GFP_KERNEL);
if (!inst)
return -ENOMEM;
ctx = skcipher_instance_ctx(inst);
crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
mask = crypto_requires_off(algt->type, algt->mask,
CRYPTO_ALG_NEED_FALLBACK |
CRYPTO_ALG_ASYNC);
err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
if (err == -ENOENT) {
err = -ENAMETOOLONG;
if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
cipher_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
}
if (err)
goto err_free_inst;
alg = crypto_skcipher_spawn_alg(&ctx->spawn);
err = -EINVAL;
if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
goto err_drop_spawn;
if (crypto_skcipher_alg_ivsize(alg))
goto err_drop_spawn;
err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
&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(ctx->name, cipher_name + 4, sizeof(ctx->name));
if (len < 2 || len >= sizeof(ctx->name))
goto err_drop_spawn;
if (ctx->name[len - 1] != ')')
goto err_drop_spawn;
ctx->name[len - 1] = 0;
if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
"xts(%s)", ctx->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 = XTS_BLOCK_SIZE;
inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
(__alignof__(u64) - 1);
inst->alg.ivsize = XTS_BLOCK_SIZE;
inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
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_inst;
err = skcipher_register_instance(tmpl, inst);
if (err)
goto err_drop_spawn;
out:
return err;
err_drop_spawn:
crypto_drop_skcipher(&ctx->spawn);
err_free_inst:
kfree(inst);
goto out;
}
static struct crypto_template crypto_tmpl = {
.name = "xts",
.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("XTS block cipher mode");
MODULE_ALIAS_CRYPTO("xts");