arm64/crypto: AES in CCM mode using ARMv8 Crypto Extensions
This patch adds support for the AES-CCM encryption algorithm for CPUs that
have support for the AES part of the ARM v8 Crypto Extensions.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c
new file mode 100644
index 0000000..9e6cdde9
--- /dev/null
+++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
@@ -0,0 +1,297 @@
+/*
+ * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
+ *
+ * Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/neon.h>
+#include <asm/unaligned.h>
+#include <crypto/aes.h>
+#include <crypto/algapi.h>
+#include <crypto/scatterwalk.h>
+#include <linux/crypto.h>
+#include <linux/module.h>
+
+static int num_rounds(struct crypto_aes_ctx *ctx)
+{
+ /*
+ * # of rounds specified by AES:
+ * 128 bit key 10 rounds
+ * 192 bit key 12 rounds
+ * 256 bit key 14 rounds
+ * => n byte key => 6 + (n/4) rounds
+ */
+ return 6 + ctx->key_length / 4;
+}
+
+asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
+ u32 *macp, u32 const rk[], u32 rounds);
+
+asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
+ u32 const rk[], u32 rounds, u8 mac[],
+ u8 ctr[]);
+
+asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
+ u32 const rk[], u32 rounds, u8 mac[],
+ u8 ctr[]);
+
+asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
+ u32 rounds);
+
+static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
+ unsigned int key_len)
+{
+ struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
+ int ret;
+
+ ret = crypto_aes_expand_key(ctx, in_key, key_len);
+ if (!ret)
+ return 0;
+
+ tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
+ return -EINVAL;
+}
+
+static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
+{
+ if ((authsize & 1) || authsize < 4)
+ return -EINVAL;
+ return 0;
+}
+
+static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
+{
+ struct crypto_aead *aead = crypto_aead_reqtfm(req);
+ __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
+ u32 l = req->iv[0] + 1;
+
+ /* verify that CCM dimension 'L' is set correctly in the IV */
+ if (l < 2 || l > 8)
+ return -EINVAL;
+
+ /* verify that msglen can in fact be represented in L bytes */
+ if (l < 4 && msglen >> (8 * l))
+ return -EOVERFLOW;
+
+ /*
+ * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
+ * uses a u32 type to represent msglen so the top 4 bytes are always 0.
+ */
+ n[0] = 0;
+ n[1] = cpu_to_be32(msglen);
+
+ memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
+
+ /*
+ * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
+ * - bits 0..2 : max # of bytes required to represent msglen, minus 1
+ * (already set by caller)
+ * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
+ * - bit 6 : indicates presence of authenticate-only data
+ */
+ maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
+ if (req->assoclen)
+ maciv[0] |= 0x40;
+
+ memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
+ return 0;
+}
+
+static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
+{
+ struct crypto_aead *aead = crypto_aead_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
+ struct __packed { __be16 l; __be32 h; u16 len; } ltag;
+ struct scatter_walk walk;
+ u32 len = req->assoclen;
+ u32 macp = 0;
+
+ /* prepend the AAD with a length tag */
+ if (len < 0xff00) {
+ ltag.l = cpu_to_be16(len);
+ ltag.len = 2;
+ } else {
+ ltag.l = cpu_to_be16(0xfffe);
+ put_unaligned_be32(len, <ag.h);
+ ltag.len = 6;
+ }
+
+ ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc,
+ num_rounds(ctx));
+ scatterwalk_start(&walk, req->assoc);
+
+ do {
+ u32 n = scatterwalk_clamp(&walk, len);
+ u8 *p;
+
+ if (!n) {
+ scatterwalk_start(&walk, sg_next(walk.sg));
+ n = scatterwalk_clamp(&walk, len);
+ }
+ p = scatterwalk_map(&walk);
+ ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc,
+ num_rounds(ctx));
+ len -= n;
+
+ scatterwalk_unmap(p);
+ scatterwalk_advance(&walk, n);
+ scatterwalk_done(&walk, 0, len);
+ } while (len);
+}
+
+static int ccm_encrypt(struct aead_request *req)
+{
+ struct crypto_aead *aead = crypto_aead_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
+ struct blkcipher_desc desc = { .info = req->iv };
+ struct blkcipher_walk walk;
+ u8 __aligned(8) mac[AES_BLOCK_SIZE];
+ u8 buf[AES_BLOCK_SIZE];
+ u32 len = req->cryptlen;
+ int err;
+
+ err = ccm_init_mac(req, mac, len);
+ if (err)
+ return err;
+
+ kernel_neon_begin_partial(6);
+
+ if (req->assoclen)
+ ccm_calculate_auth_mac(req, mac);
+
+ /* preserve the original iv for the final round */
+ memcpy(buf, req->iv, AES_BLOCK_SIZE);
+
+ blkcipher_walk_init(&walk, req->dst, req->src, len);
+ err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
+ AES_BLOCK_SIZE);
+
+ while (walk.nbytes) {
+ u32 tail = walk.nbytes % AES_BLOCK_SIZE;
+
+ if (walk.nbytes == len)
+ tail = 0;
+
+ ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ walk.nbytes - tail, ctx->key_enc,
+ num_rounds(ctx), mac, walk.iv);
+
+ len -= walk.nbytes - tail;
+ err = blkcipher_walk_done(&desc, &walk, tail);
+ }
+ if (!err)
+ ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
+
+ kernel_neon_end();
+
+ if (err)
+ return err;
+
+ /* copy authtag to end of dst */
+ scatterwalk_map_and_copy(mac, req->dst, req->cryptlen,
+ crypto_aead_authsize(aead), 1);
+
+ return 0;
+}
+
+static int ccm_decrypt(struct aead_request *req)
+{
+ struct crypto_aead *aead = crypto_aead_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
+ unsigned int authsize = crypto_aead_authsize(aead);
+ struct blkcipher_desc desc = { .info = req->iv };
+ struct blkcipher_walk walk;
+ u8 __aligned(8) mac[AES_BLOCK_SIZE];
+ u8 buf[AES_BLOCK_SIZE];
+ u32 len = req->cryptlen - authsize;
+ int err;
+
+ err = ccm_init_mac(req, mac, len);
+ if (err)
+ return err;
+
+ kernel_neon_begin_partial(6);
+
+ if (req->assoclen)
+ ccm_calculate_auth_mac(req, mac);
+
+ /* preserve the original iv for the final round */
+ memcpy(buf, req->iv, AES_BLOCK_SIZE);
+
+ blkcipher_walk_init(&walk, req->dst, req->src, len);
+ err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
+ AES_BLOCK_SIZE);
+
+ while (walk.nbytes) {
+ u32 tail = walk.nbytes % AES_BLOCK_SIZE;
+
+ if (walk.nbytes == len)
+ tail = 0;
+
+ ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ walk.nbytes - tail, ctx->key_enc,
+ num_rounds(ctx), mac, walk.iv);
+
+ len -= walk.nbytes - tail;
+ err = blkcipher_walk_done(&desc, &walk, tail);
+ }
+ if (!err)
+ ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
+
+ kernel_neon_end();
+
+ if (err)
+ return err;
+
+ /* compare calculated auth tag with the stored one */
+ scatterwalk_map_and_copy(buf, req->src, req->cryptlen - authsize,
+ authsize, 0);
+
+ if (memcmp(mac, buf, authsize))
+ return -EBADMSG;
+ return 0;
+}
+
+static struct crypto_alg ccm_aes_alg = {
+ .cra_name = "ccm(aes)",
+ .cra_driver_name = "ccm-aes-ce",
+ .cra_priority = 300,
+ .cra_flags = CRYPTO_ALG_TYPE_AEAD,
+ .cra_blocksize = 1,
+ .cra_ctxsize = sizeof(struct crypto_aes_ctx),
+ .cra_alignmask = 7,
+ .cra_type = &crypto_aead_type,
+ .cra_module = THIS_MODULE,
+ .cra_aead = {
+ .ivsize = AES_BLOCK_SIZE,
+ .maxauthsize = AES_BLOCK_SIZE,
+ .setkey = ccm_setkey,
+ .setauthsize = ccm_setauthsize,
+ .encrypt = ccm_encrypt,
+ .decrypt = ccm_decrypt,
+ }
+};
+
+static int __init aes_mod_init(void)
+{
+ if (!(elf_hwcap & HWCAP_AES))
+ return -ENODEV;
+ return crypto_register_alg(&ccm_aes_alg);
+}
+
+static void __exit aes_mod_exit(void)
+{
+ crypto_unregister_alg(&ccm_aes_alg);
+}
+
+module_init(aes_mod_init);
+module_exit(aes_mod_exit);
+
+MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
+MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("ccm(aes)");