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-rw-r--r--crypto/lrw.c431
1 files changed, 431 insertions, 0 deletions
diff --git a/crypto/lrw.c b/crypto/lrw.c
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+// 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
+ * https://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 lrw_tfm_ctx {
+ 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 lrw_request_ctx {
+ be128 t;
+ struct skcipher_request subreq;
+};
+
+static inline void lrw_setbit128_bbe(void *b, int bit)
+{
+ __set_bit(bit ^ (0x80 -
+#ifdef __BIG_ENDIAN
+ BITS_PER_LONG
+#else
+ BITS_PER_BYTE
+#endif
+ ), b);
+}
+
+static int lrw_setkey(struct crypto_skcipher *parent, const u8 *key,
+ unsigned int keylen)
+{
+ struct lrw_tfm_ctx *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++) {
+ lrw_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 = lrw_next_index(&counter);
+ * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
+ */
+static int lrw_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 lrw_next_index() calls again.
+ */
+static int lrw_xor_tweak(struct skcipher_request *req, bool second_pass)
+{
+ const int bs = LRW_BLOCK_SIZE;
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ const struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct lrw_request_ctx *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[lrw_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 lrw_xor_tweak_pre(struct skcipher_request *req)
+{
+ return lrw_xor_tweak(req, false);
+}
+
+static int lrw_xor_tweak_post(struct skcipher_request *req)
+{
+ return lrw_xor_tweak(req, true);
+}
+
+static void lrw_crypt_done(struct crypto_async_request *areq, int err)
+{
+ struct skcipher_request *req = areq->data;
+
+ if (!err) {
+ struct lrw_request_ctx *rctx = skcipher_request_ctx(req);
+
+ rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
+ err = lrw_xor_tweak_post(req);
+ }
+
+ skcipher_request_complete(req, err);
+}
+
+static void lrw_init_crypt(struct skcipher_request *req)
+{
+ const struct lrw_tfm_ctx *ctx =
+ crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
+ struct lrw_request_ctx *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, lrw_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 lrw_encrypt(struct skcipher_request *req)
+{
+ struct lrw_request_ctx *rctx = skcipher_request_ctx(req);
+ struct skcipher_request *subreq = &rctx->subreq;
+
+ lrw_init_crypt(req);
+ return lrw_xor_tweak_pre(req) ?:
+ crypto_skcipher_encrypt(subreq) ?:
+ lrw_xor_tweak_post(req);
+}
+
+static int lrw_decrypt(struct skcipher_request *req)
+{
+ struct lrw_request_ctx *rctx = skcipher_request_ctx(req);
+ struct skcipher_request *subreq = &rctx->subreq;
+
+ lrw_init_crypt(req);
+ return lrw_xor_tweak_pre(req) ?:
+ crypto_skcipher_decrypt(subreq) ?:
+ lrw_xor_tweak_post(req);
+}
+
+static int lrw_init_tfm(struct crypto_skcipher *tfm)
+{
+ struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+ struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
+ struct lrw_tfm_ctx *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 lrw_request_ctx));
+
+ return 0;
+}
+
+static void lrw_exit_tfm(struct crypto_skcipher *tfm)
+{
+ struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+ if (ctx->table)
+ gf128mul_free_64k(ctx->table);
+ crypto_free_skcipher(ctx->child);
+}
+
+static void lrw_free_instance(struct skcipher_instance *inst)
+{
+ crypto_drop_skcipher(skcipher_instance_ctx(inst));
+ kfree(inst);
+}
+
+static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+ struct crypto_skcipher_spawn *spawn;
+ struct skcipher_instance *inst;
+ struct skcipher_alg *alg;
+ const char *cipher_name;
+ char ecb_name[CRYPTO_MAX_ALG_NAME];
+ u32 mask;
+ int err;
+
+ err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
+ if (err)
+ return err;
+
+ 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);
+
+ err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),
+ cipher_name, 0, 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,
+ skcipher_crypto_instance(inst),
+ ecb_name, 0, 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_free_inst;
+
+ if (crypto_skcipher_alg_ivsize(alg))
+ goto err_free_inst;
+
+ err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
+ &alg->base);
+ if (err)
+ goto err_free_inst;
+
+ 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)) {
+ int len;
+
+ len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
+ if (len < 2)
+ goto err_free_inst;
+
+ if (ecb_name[len - 1] != ')')
+ goto err_free_inst;
+
+ 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_free_inst;
+ }
+ } else
+ goto err_free_inst;
+
+ 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 lrw_tfm_ctx);
+
+ inst->alg.init = lrw_init_tfm;
+ inst->alg.exit = lrw_exit_tfm;
+
+ inst->alg.setkey = lrw_setkey;
+ inst->alg.encrypt = lrw_encrypt;
+ inst->alg.decrypt = lrw_decrypt;
+
+ inst->free = lrw_free_instance;
+
+ err = skcipher_register_instance(tmpl, inst);
+ if (err) {
+err_free_inst:
+ lrw_free_instance(inst);
+ }
+ return err;
+}
+
+static struct crypto_template lrw_tmpl = {
+ .name = "lrw",
+ .create = lrw_create,
+ .module = THIS_MODULE,
+};
+
+static int __init lrw_module_init(void)
+{
+ return crypto_register_template(&lrw_tmpl);
+}
+
+static void __exit lrw_module_exit(void)
+{
+ crypto_unregister_template(&lrw_tmpl);
+}
+
+subsys_initcall(lrw_module_init);
+module_exit(lrw_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LRW block cipher mode");
+MODULE_ALIAS_CRYPTO("lrw");
+MODULE_SOFTDEP("pre: ecb");