[v4,20/32] crypto: arm/aes-ce - provide a synchronous version of ctr(aes)
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Message ID 20190702194150.10405-21-ard.biesheuvel@linaro.org
State Accepted
Delegated to: Herbert Xu
Headers show
Series
  • crypto: AES cleanup
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Commit Message

Ard Biesheuvel July 2, 2019, 7:41 p.m. UTC
AES in CTR mode is used by modes such as GCM and CCM, which are often
used in contexts where only synchronous ciphers are permitted. So
provide a synchronous version of ctr(aes) based on the existing code.
This requires a non-SIMD fallback to deal with invocations occurring
from a context where SIMD instructions may not be used. We have a
helper for this now in the AES library, so wire that up.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/arm/crypto/aes-ce-glue.c | 43 ++++++++++++++++++++
 1 file changed, 43 insertions(+)

Patch
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diff --git a/arch/arm/crypto/aes-ce-glue.c b/arch/arm/crypto/aes-ce-glue.c
index e6da3e30018b..1d93da29d03a 100644
--- a/arch/arm/crypto/aes-ce-glue.c
+++ b/arch/arm/crypto/aes-ce-glue.c
@@ -10,8 +10,10 @@ 
 
 #include <asm/hwcap.h>
 #include <asm/neon.h>
+#include <asm/simd.h>
 #include <asm/unaligned.h>
 #include <crypto/aes.h>
+#include <crypto/ctr.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/cpufeature.h>
@@ -289,6 +291,29 @@  static int ctr_encrypt(struct skcipher_request *req)
 	return err;
 }
 
+static void ctr_encrypt_one(struct crypto_skcipher *tfm, const u8 *src, u8 *dst)
+{
+	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+	unsigned long flags;
+
+	/*
+	 * Temporarily disable interrupts to avoid races where
+	 * cachelines are evicted when the CPU is interrupted
+	 * to do something else.
+	 */
+	local_irq_save(flags);
+	aes_encrypt(ctx, dst, src);
+	local_irq_restore(flags);
+}
+
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
+	if (!crypto_simd_usable())
+		return crypto_ctr_encrypt_walk(req, ctr_encrypt_one);
+
+	return ctr_encrypt(req);
+}
+
 static int xts_encrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
@@ -378,6 +403,21 @@  static struct skcipher_alg aes_algs[] = { {
 	.setkey			= ce_aes_setkey,
 	.encrypt		= ctr_encrypt,
 	.decrypt		= ctr_encrypt,
+}, {
+	.base.cra_name		= "ctr(aes)",
+	.base.cra_driver_name	= "ctr-aes-ce-sync",
+	.base.cra_priority	= 300 - 1,
+	.base.cra_blocksize	= 1,
+	.base.cra_ctxsize	= sizeof(struct crypto_aes_ctx),
+	.base.cra_module	= THIS_MODULE,
+
+	.min_keysize		= AES_MIN_KEY_SIZE,
+	.max_keysize		= AES_MAX_KEY_SIZE,
+	.ivsize			= AES_BLOCK_SIZE,
+	.chunksize		= AES_BLOCK_SIZE,
+	.setkey			= ce_aes_setkey,
+	.encrypt		= ctr_encrypt_sync,
+	.decrypt		= ctr_encrypt_sync,
 }, {
 	.base.cra_name		= "__xts(aes)",
 	.base.cra_driver_name	= "__xts-aes-ce",
@@ -421,6 +461,9 @@  static int __init aes_init(void)
 		return err;
 
 	for (i = 0; i < ARRAY_SIZE(aes_algs); i++) {
+		if (!(aes_algs[i].base.cra_flags & CRYPTO_ALG_INTERNAL))
+			continue;
+
 		algname = aes_algs[i].base.cra_name + 2;
 		drvname = aes_algs[i].base.cra_driver_name + 2;
 		basename = aes_algs[i].base.cra_driver_name;