crypto: add CMAC support to CryptoAPI
Patch adds support for NIST recommended block cipher mode CMAC to CryptoAPI.
This work is based on Tom St Denis' earlier patch,
http://marc.info/?l=linux-crypto-vger&m=135877306305466&w=2
Cc: Tom St Denis <tstdenis@elliptictech.com>
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/cmac.c b/crypto/cmac.c
new file mode 100644
index 0000000..50880cf
--- /dev/null
+++ b/crypto/cmac.c
@@ -0,0 +1,315 @@
+/*
+ * CMAC: Cipher Block Mode for Authentication
+ *
+ * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
+ *
+ * Based on work by:
+ * Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
+ * Based on crypto/xcbc.c:
+ * Copyright © 2006 USAGI/WIDE Project,
+ * Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
+ *
+ * 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.
+ *
+ */
+
+#include <crypto/internal/hash.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+/*
+ * +------------------------
+ * | <parent tfm>
+ * +------------------------
+ * | cmac_tfm_ctx
+ * +------------------------
+ * | consts (block size * 2)
+ * +------------------------
+ */
+struct cmac_tfm_ctx {
+ struct crypto_cipher *child;
+ u8 ctx[];
+};
+
+/*
+ * +------------------------
+ * | <shash desc>
+ * +------------------------
+ * | cmac_desc_ctx
+ * +------------------------
+ * | odds (block size)
+ * +------------------------
+ * | prev (block size)
+ * +------------------------
+ */
+struct cmac_desc_ctx {
+ unsigned int len;
+ u8 ctx[];
+};
+
+static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
+ const u8 *inkey, unsigned int keylen)
+{
+ unsigned long alignmask = crypto_shash_alignmask(parent);
+ struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
+ unsigned int bs = crypto_shash_blocksize(parent);
+ __be64 *consts = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
+ u64 _const[2];
+ int i, err = 0;
+ u8 msb_mask, gfmask;
+
+ err = crypto_cipher_setkey(ctx->child, inkey, keylen);
+ if (err)
+ return err;
+
+ /* encrypt the zero block */
+ memset(consts, 0, bs);
+ crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);
+
+ switch (bs) {
+ case 16:
+ gfmask = 0x87;
+ _const[0] = be64_to_cpu(consts[1]);
+ _const[1] = be64_to_cpu(consts[0]);
+
+ /* gf(2^128) multiply zero-ciphertext with u and u^2 */
+ for (i = 0; i < 4; i += 2) {
+ msb_mask = ((s64)_const[1] >> 63) & gfmask;
+ _const[1] = (_const[1] << 1) | (_const[0] >> 63);
+ _const[0] = (_const[0] << 1) ^ msb_mask;
+
+ consts[i + 0] = cpu_to_be64(_const[1]);
+ consts[i + 1] = cpu_to_be64(_const[0]);
+ }
+
+ break;
+ case 8:
+ gfmask = 0x1B;
+ _const[0] = be64_to_cpu(consts[0]);
+
+ /* gf(2^64) multiply zero-ciphertext with u and u^2 */
+ for (i = 0; i < 2; i++) {
+ msb_mask = ((s64)_const[0] >> 63) & gfmask;
+ _const[0] = (_const[0] << 1) ^ msb_mask;
+
+ consts[i] = cpu_to_be64(_const[0]);
+ }
+
+ break;
+ }
+
+ return 0;
+}
+
+static int crypto_cmac_digest_init(struct shash_desc *pdesc)
+{
+ unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
+ struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
+ int bs = crypto_shash_blocksize(pdesc->tfm);
+ u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs;
+
+ ctx->len = 0;
+ memset(prev, 0, bs);
+
+ return 0;
+}
+
+static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
+ unsigned int len)
+{
+ struct crypto_shash *parent = pdesc->tfm;
+ unsigned long alignmask = crypto_shash_alignmask(parent);
+ struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
+ struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
+ struct crypto_cipher *tfm = tctx->child;
+ int bs = crypto_shash_blocksize(parent);
+ u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
+ u8 *prev = odds + bs;
+
+ /* checking the data can fill the block */
+ if ((ctx->len + len) <= bs) {
+ memcpy(odds + ctx->len, p, len);
+ ctx->len += len;
+ return 0;
+ }
+
+ /* filling odds with new data and encrypting it */
+ memcpy(odds + ctx->len, p, bs - ctx->len);
+ len -= bs - ctx->len;
+ p += bs - ctx->len;
+
+ crypto_xor(prev, odds, bs);
+ crypto_cipher_encrypt_one(tfm, prev, prev);
+
+ /* clearing the length */
+ ctx->len = 0;
+
+ /* encrypting the rest of data */
+ while (len > bs) {
+ crypto_xor(prev, p, bs);
+ crypto_cipher_encrypt_one(tfm, prev, prev);
+ p += bs;
+ len -= bs;
+ }
+
+ /* keeping the surplus of blocksize */
+ if (len) {
+ memcpy(odds, p, len);
+ ctx->len = len;
+ }
+
+ return 0;
+}
+
+static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out)
+{
+ struct crypto_shash *parent = pdesc->tfm;
+ unsigned long alignmask = crypto_shash_alignmask(parent);
+ struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
+ struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
+ struct crypto_cipher *tfm = tctx->child;
+ int bs = crypto_shash_blocksize(parent);
+ u8 *consts = PTR_ALIGN((void *)tctx->ctx, alignmask + 1);
+ u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
+ u8 *prev = odds + bs;
+ unsigned int offset = 0;
+
+ if (ctx->len != bs) {
+ unsigned int rlen;
+ u8 *p = odds + ctx->len;
+
+ *p = 0x80;
+ p++;
+
+ rlen = bs - ctx->len - 1;
+ if (rlen)
+ memset(p, 0, rlen);
+
+ offset += bs;
+ }
+
+ crypto_xor(prev, odds, bs);
+ crypto_xor(prev, consts + offset, bs);
+
+ crypto_cipher_encrypt_one(tfm, out, prev);
+
+ return 0;
+}
+
+static int cmac_init_tfm(struct crypto_tfm *tfm)
+{
+ struct crypto_cipher *cipher;
+ struct crypto_instance *inst = (void *)tfm->__crt_alg;
+ struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+ struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
+
+ cipher = crypto_spawn_cipher(spawn);
+ if (IS_ERR(cipher))
+ return PTR_ERR(cipher);
+
+ ctx->child = cipher;
+
+ return 0;
+};
+
+static void cmac_exit_tfm(struct crypto_tfm *tfm)
+{
+ struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
+ crypto_free_cipher(ctx->child);
+}
+
+static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+ struct shash_instance *inst;
+ struct crypto_alg *alg;
+ unsigned long alignmask;
+ int err;
+
+ err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
+ if (err)
+ return err;
+
+ alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
+ CRYPTO_ALG_TYPE_MASK);
+ if (IS_ERR(alg))
+ return PTR_ERR(alg);
+
+ switch (alg->cra_blocksize) {
+ case 16:
+ case 8:
+ break;
+ default:
+ goto out_put_alg;
+ }
+
+ inst = shash_alloc_instance("cmac", alg);
+ err = PTR_ERR(inst);
+ if (IS_ERR(inst))
+ goto out_put_alg;
+
+ err = crypto_init_spawn(shash_instance_ctx(inst), alg,
+ shash_crypto_instance(inst),
+ CRYPTO_ALG_TYPE_MASK);
+ if (err)
+ goto out_free_inst;
+
+ alignmask = alg->cra_alignmask | (sizeof(long) - 1);
+ inst->alg.base.cra_alignmask = alignmask;
+ inst->alg.base.cra_priority = alg->cra_priority;
+ inst->alg.base.cra_blocksize = alg->cra_blocksize;
+
+ inst->alg.digestsize = alg->cra_blocksize;
+ inst->alg.descsize =
+ ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
+ + (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
+ + alg->cra_blocksize * 2;
+
+ inst->alg.base.cra_ctxsize =
+ ALIGN(sizeof(struct cmac_tfm_ctx), alignmask + 1)
+ + alg->cra_blocksize * 2;
+
+ inst->alg.base.cra_init = cmac_init_tfm;
+ inst->alg.base.cra_exit = cmac_exit_tfm;
+
+ inst->alg.init = crypto_cmac_digest_init;
+ inst->alg.update = crypto_cmac_digest_update;
+ inst->alg.final = crypto_cmac_digest_final;
+ inst->alg.setkey = crypto_cmac_digest_setkey;
+
+ err = shash_register_instance(tmpl, inst);
+ if (err) {
+out_free_inst:
+ shash_free_instance(shash_crypto_instance(inst));
+ }
+
+out_put_alg:
+ crypto_mod_put(alg);
+ return err;
+}
+
+static struct crypto_template crypto_cmac_tmpl = {
+ .name = "cmac",
+ .create = cmac_create,
+ .free = shash_free_instance,
+ .module = THIS_MODULE,
+};
+
+static int __init crypto_cmac_module_init(void)
+{
+ return crypto_register_template(&crypto_cmac_tmpl);
+}
+
+static void __exit crypto_cmac_module_exit(void)
+{
+ crypto_unregister_template(&crypto_cmac_tmpl);
+}
+
+module_init(crypto_cmac_module_init);
+module_exit(crypto_cmac_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CMAC keyed hash algorithm");