[PATCH v2 1/1] crypto: atmel-aes: add support to the XTS mode

From: Cyrille Pitchen
Date: Mon Oct 03 2016 - 08:32:46 EST

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This patch adds the xts(aes) algorithm, which is supported from
hardware version 0x500 and above (sama5d2x).

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
---
ChangeLog:

v1 -> v2:
- fix typo in comment inside atmel_aes_xts_process_data():
s/reverted/reversed/
- use xts_check_key() from atmel_aes_xts_setkey() as suggested by
Stephan Mueller.

drivers/crypto/atmel-aes-regs.h | 4 +
drivers/crypto/atmel-aes.c | 185 ++++++++++++++++++++++++++++++++++++++--
2 files changed, 183 insertions(+), 6 deletions(-)

diff --git a/drivers/crypto/atmel-aes-regs.h b/drivers/crypto/atmel-aes-regs.h
index 6c2951bb70b1..0ec04407b533 100644
--- a/drivers/crypto/atmel-aes-regs.h
+++ b/drivers/crypto/atmel-aes-regs.h
@@ -28,6 +28,7 @@
#define AES_MR_OPMOD_CFB (0x3 << 12)
#define AES_MR_OPMOD_CTR (0x4 << 12)
#define AES_MR_OPMOD_GCM (0x5 << 12)
+#define AES_MR_OPMOD_XTS (0x6 << 12)
#define AES_MR_LOD (0x1 << 15)
#define AES_MR_CFBS_MASK (0x7 << 16)
#define AES_MR_CFBS_128b (0x0 << 16)
@@ -67,6 +68,9 @@
#define AES_CTRR 0x98
#define AES_GCMHR(x) (0x9c + ((x) * 0x04))

+#define AES_TWR(x) (0xc0 + ((x) * 0x04))
+#define AES_ALPHAR(x) (0xd0 + ((x) * 0x04))
+
#define AES_HW_VERSION 0xFC

#endif /* __ATMEL_AES_REGS_H__ */
diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index 1d9e7bd3f377..6b656f4a9378 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -36,6 +36,7 @@
#include <crypto/scatterwalk.h>
#include <crypto/algapi.h>
#include <crypto/aes.h>
+#include <crypto/xts.h>
#include <crypto/internal/aead.h>
#include <linux/platform_data/crypto-atmel.h>
#include <dt-bindings/dma/at91.h>
@@ -68,6 +69,7 @@
#define AES_FLAGS_CFB8 (AES_MR_OPMOD_CFB | AES_MR_CFBS_8b)
#define AES_FLAGS_CTR AES_MR_OPMOD_CTR
#define AES_FLAGS_GCM AES_MR_OPMOD_GCM
+#define AES_FLAGS_XTS AES_MR_OPMOD_XTS

#define AES_FLAGS_MODE_MASK (AES_FLAGS_OPMODE_MASK | \
AES_FLAGS_ENCRYPT | \
@@ -89,6 +91,7 @@ struct atmel_aes_caps {
bool has_cfb64;
bool has_ctr32;
bool has_gcm;
+ bool has_xts;
u32 max_burst_size;
};

@@ -135,6 +138,12 @@ struct atmel_aes_gcm_ctx {
atmel_aes_fn_t ghash_resume;
};

+struct atmel_aes_xts_ctx {
+ struct atmel_aes_base_ctx base;
+
+ u32 key2[AES_KEYSIZE_256 / sizeof(u32)];
+};
+
struct atmel_aes_reqctx {
unsigned long mode;
};
@@ -282,6 +291,20 @@ static const char *atmel_aes_reg_name(u32 offset, char *tmp, size_t sz)
snprintf(tmp, sz, "GCMHR[%u]", (offset - AES_GCMHR(0)) >> 2);
break;

+ case AES_TWR(0):
+ case AES_TWR(1):
+ case AES_TWR(2):
+ case AES_TWR(3):
+ snprintf(tmp, sz, "TWR[%u]", (offset - AES_TWR(0)) >> 2);
+ break;
+
+ case AES_ALPHAR(0):
+ case AES_ALPHAR(1):
+ case AES_ALPHAR(2):
+ case AES_ALPHAR(3):
+ snprintf(tmp, sz, "ALPHAR[%u]", (offset - AES_ALPHAR(0)) >> 2);
+ break;
+
default:
snprintf(tmp, sz, "0x%02x", offset);
break;
@@ -453,15 +476,15 @@ static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
return err;
}

-static void atmel_aes_write_ctrl(struct atmel_aes_dev *dd, bool use_dma,
- const u32 *iv)
+static void atmel_aes_write_ctrl_key(struct atmel_aes_dev *dd, bool use_dma,
+ const u32 *iv, const u32 *key, int keylen)
{
u32 valmr = 0;

/* MR register must be set before IV registers */
- if (dd->ctx->keylen == AES_KEYSIZE_128)
+ if (keylen == AES_KEYSIZE_128)
valmr |= AES_MR_KEYSIZE_128;
- else if (dd->ctx->keylen == AES_KEYSIZE_192)
+ else if (keylen == AES_KEYSIZE_192)
valmr |= AES_MR_KEYSIZE_192;
else
valmr |= AES_MR_KEYSIZE_256;
@@ -478,13 +501,19 @@ static void atmel_aes_write_ctrl(struct atmel_aes_dev *dd, bool use_dma,

atmel_aes_write(dd, AES_MR, valmr);

- atmel_aes_write_n(dd, AES_KEYWR(0), dd->ctx->key,
- SIZE_IN_WORDS(dd->ctx->keylen));
+ atmel_aes_write_n(dd, AES_KEYWR(0), key, SIZE_IN_WORDS(keylen));

if (iv && (valmr & AES_MR_OPMOD_MASK) != AES_MR_OPMOD_ECB)
atmel_aes_write_block(dd, AES_IVR(0), iv);
}

+static inline void atmel_aes_write_ctrl(struct atmel_aes_dev *dd, bool use_dma,
+ const u32 *iv)
+
+{
+ atmel_aes_write_ctrl_key(dd, use_dma, iv,
+ dd->ctx->key, dd->ctx->keylen);
+}

/* CPU transfer */

@@ -1769,6 +1798,137 @@ static struct aead_alg aes_gcm_alg = {
};

+/* xts functions */
+
+static inline struct atmel_aes_xts_ctx *
+atmel_aes_xts_ctx_cast(struct atmel_aes_base_ctx *ctx)
+{
+ return container_of(ctx, struct atmel_aes_xts_ctx, base);
+}
+
+static int atmel_aes_xts_process_data(struct atmel_aes_dev *dd);
+
+static int atmel_aes_xts_start(struct atmel_aes_dev *dd)
+{
+ struct atmel_aes_xts_ctx *ctx = atmel_aes_xts_ctx_cast(dd->ctx);
+ struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
+ struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
+ unsigned long flags;
+ int err;
+
+ atmel_aes_set_mode(dd, rctx);
+
+ err = atmel_aes_hw_init(dd);
+ if (err)
+ return atmel_aes_complete(dd, err);
+
+ /* Compute the tweak value from req->info with ecb(aes). */
+ flags = dd->flags;
+ dd->flags &= ~AES_FLAGS_MODE_MASK;
+ dd->flags |= (AES_FLAGS_ECB | AES_FLAGS_ENCRYPT);
+ atmel_aes_write_ctrl_key(dd, false, NULL,
+ ctx->key2, ctx->base.keylen);
+ dd->flags = flags;
+
+ atmel_aes_write_block(dd, AES_IDATAR(0), req->info);
+ return atmel_aes_wait_for_data_ready(dd, atmel_aes_xts_process_data);
+}
+
+static int atmel_aes_xts_process_data(struct atmel_aes_dev *dd)
+{
+ struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
+ bool use_dma = (req->nbytes >= ATMEL_AES_DMA_THRESHOLD);
+ u32 tweak[AES_BLOCK_SIZE / sizeof(u32)];
+ static const u32 one[AES_BLOCK_SIZE / sizeof(u32)] = {cpu_to_le32(1), };
+ u8 *tweak_bytes = (u8 *)tweak;
+ int i;
+
+ /* Read the computed ciphered tweak value. */
+ atmel_aes_read_block(dd, AES_ODATAR(0), tweak);
+ /*
+ * Hardware quirk:
+ * the order of the ciphered tweak bytes need to be reversed before
+ * writing them into the ODATARx registers.
+ */
+ for (i = 0; i < AES_BLOCK_SIZE/2; ++i) {
+ u8 tmp = tweak_bytes[AES_BLOCK_SIZE - 1 - i];
+
+ tweak_bytes[AES_BLOCK_SIZE - 1 - i] = tweak_bytes[i];
+ tweak_bytes[i] = tmp;
+ }
+
+ /* Process the data. */
+ atmel_aes_write_ctrl(dd, use_dma, NULL);
+ atmel_aes_write_block(dd, AES_TWR(0), tweak);
+ atmel_aes_write_block(dd, AES_ALPHAR(0), one);
+ if (use_dma)
+ return atmel_aes_dma_start(dd, req->src, req->dst, req->nbytes,
+ atmel_aes_transfer_complete);
+
+ return atmel_aes_cpu_start(dd, req->src, req->dst, req->nbytes,
+ atmel_aes_transfer_complete);
+}
+
+static int atmel_aes_xts_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
+ unsigned int keylen)
+{
+ struct atmel_aes_xts_ctx *ctx = crypto_ablkcipher_ctx(tfm);
+ int err;
+
+ err = xts_check_key(crypto_ablkcipher_tfm(tfm), key, keylen);
+ if (err)
+ return err;
+
+ memcpy(ctx->base.key, key, keylen/2);
+ memcpy(ctx->key2, key + keylen/2, keylen/2);
+ ctx->base.keylen = keylen/2;
+
+ return 0;
+}
+
+static int atmel_aes_xts_encrypt(struct ablkcipher_request *req)
+{
+ return atmel_aes_crypt(req, AES_FLAGS_XTS | AES_FLAGS_ENCRYPT);
+}
+
+static int atmel_aes_xts_decrypt(struct ablkcipher_request *req)
+{
+ return atmel_aes_crypt(req, AES_FLAGS_XTS);
+}
+
+static int atmel_aes_xts_cra_init(struct crypto_tfm *tfm)
+{
+ struct atmel_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+
+ tfm->crt_ablkcipher.reqsize = sizeof(struct atmel_aes_reqctx);
+ ctx->base.start = atmel_aes_xts_start;
+
+ return 0;
+}
+
+static struct crypto_alg aes_xts_alg = {
+ .cra_name = "xts(aes)",
+ .cra_driver_name = "atmel-xts-aes",
+ .cra_priority = ATMEL_AES_PRIORITY,
+ .cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
+ .cra_blocksize = AES_BLOCK_SIZE,
+ .cra_ctxsize = sizeof(struct atmel_aes_xts_ctx),
+ .cra_alignmask = 0xf,
+ .cra_type = &crypto_ablkcipher_type,
+ .cra_module = THIS_MODULE,
+ .cra_init = atmel_aes_xts_cra_init,
+ .cra_exit = atmel_aes_cra_exit,
+ .cra_u.ablkcipher = {
+ .min_keysize = 2 * AES_MIN_KEY_SIZE,
+ .max_keysize = 2 * AES_MAX_KEY_SIZE,
+ .ivsize = AES_BLOCK_SIZE,
+ .setkey = atmel_aes_xts_setkey,
+ .encrypt = atmel_aes_xts_encrypt,
+ .decrypt = atmel_aes_xts_decrypt,
+ }
+};
+
+
/* Probe functions */

static int atmel_aes_buff_init(struct atmel_aes_dev *dd)
@@ -1877,6 +2037,9 @@ static void atmel_aes_unregister_algs(struct atmel_aes_dev *dd)
{
int i;

+ if (dd->caps.has_xts)
+ crypto_unregister_alg(&aes_xts_alg);
+
if (dd->caps.has_gcm)
crypto_unregister_aead(&aes_gcm_alg);

@@ -1909,8 +2072,16 @@ static int atmel_aes_register_algs(struct atmel_aes_dev *dd)
goto err_aes_gcm_alg;
}

+ if (dd->caps.has_xts) {
+ err = crypto_register_alg(&aes_xts_alg);
+ if (err)
+ goto err_aes_xts_alg;
+ }
+
return 0;

+err_aes_xts_alg:
+ crypto_unregister_aead(&aes_gcm_alg);
err_aes_gcm_alg:
crypto_unregister_alg(&aes_cfb64_alg);
err_aes_cfb64_alg:
@@ -1928,6 +2099,7 @@ static void atmel_aes_get_cap(struct atmel_aes_dev *dd)
dd->caps.has_cfb64 = 0;
dd->caps.has_ctr32 = 0;
dd->caps.has_gcm = 0;
+ dd->caps.has_xts = 0;
dd->caps.max_burst_size = 1;

/* keep only major version number */
@@ -1937,6 +2109,7 @@ static void atmel_aes_get_cap(struct atmel_aes_dev *dd)
dd->caps.has_cfb64 = 1;
dd->caps.has_ctr32 = 1;
dd->caps.has_gcm = 1;
+ dd->caps.has_xts = 1;
dd->caps.max_burst_size = 4;
break;
case 0x200:
--
2.7.4

Next message: Vladimir Davydov: "Re: [PATCH 1/2] mm: memcontrol: use special workqueue for creating per-memcg caches"
Previous message: SF Markus Elfring: "Re: [PATCH v2 2/2] KVM: s390: Use memdup_user() rather than duplicating code"
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