/* 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> #define LRW_BUFFER_SIZE 128u #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 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); } 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); crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & CRYPTO_TFM_RES_MASK); 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; } 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->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); return 0; } static void exit_crypt(struct skcipher_request *req) { struct rctx *rctx = skcipher_request_ctx(req); rctx->left = 0; if (rctx->ext) kzfree(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) 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); if (err == -EINPROGRESS) { if (rctx->left != req->cryptlen) return; goto out; } subreq = &rctx->subreq; subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG; err = do_encrypt(req, err ?: post_crypt(req)); if (rctx->left) return; out: 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) 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); if (err == -EINPROGRESS) { if (rctx->left != req->cryptlen) return; goto out; } subreq = &rctx->subreq; subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG; err = do_decrypt(req, err ?: post_crypt(req)); if (rctx->left) return; out: skcipher_request_complete(req, err); } static int decrypt(struct skcipher_request *req) { return do_decrypt(req, init_crypt(req, decrypt_done)); } 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__(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");