Add kernel backend for Bitlk key decryption.

lib/crypto_backend/crypto_backend_internal.h

@@ -55,5 +55,9 @@ int crypt_cipher_decrypt_kernel(struct crypt_cipher_kernel *ctx,
 				const char *in, char *out, size_t length,
 				const char *iv, size_t iv_length);
 void crypt_cipher_destroy_kernel(struct crypt_cipher_kernel *ctx);
+int crypt_bitlk_decrypt_key_kernel(const void *key, size_t key_length,
+				   const char *in, char *out, size_t length,
+				   const char *iv, size_t iv_length,
+				   const char *tag, size_t tag_length);
 
 #endif /* _CRYPTO_BACKEND_INTERNAL_H */

lib/crypto_backend/crypto_cipher_kernel.c

@@ -49,7 +49,7 @@
  */
 static int _crypt_cipher_init(struct crypt_cipher_kernel *ctx,
 			      const void *key, size_t key_length,
-			      struct sockaddr_alg *sa)
+			      size_t tag_length, struct sockaddr_alg *sa)
 {
 	if (!ctx)
 		return -EINVAL;
@@ -71,6 +71,11 @@ static int _crypt_cipher_init(struct crypt_cipher_kernel *ctx,
 		return -EINVAL;
 	}
 
+	if (tag_length && setsockopt(ctx->tfmfd, SOL_ALG, ALG_SET_AEAD_AUTHSIZE, NULL, tag_length) < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -EINVAL;
+	}
+
 	ctx->opfd = accept(ctx->tfmfd, NULL, 0);
 	if (ctx->opfd < 0) {
 		crypt_cipher_destroy_kernel(ctx);
@@ -93,12 +98,13 @@ int crypt_cipher_init_kernel(struct crypt_cipher_kernel *ctx, const char *name,
 
 	snprintf((char *)sa.salg_name, sizeof(sa.salg_name), "%s(%s)", mode, name);
 
-	return _crypt_cipher_init(ctx, key, key_length, &sa);
+	return _crypt_cipher_init(ctx, key, key_length, 0, &sa);
 }
 
 /* The in/out should be aligned to page boundary */
 static int _crypt_cipher_crypt(struct crypt_cipher_kernel *ctx,
-			       const char *in, char *out, size_t length,
+			       const char *in, size_t in_length,
+			       char *out, size_t out_length,
 			       const char *iv, size_t iv_length,
 			       uint32_t direction)
 {
@@ -109,7 +115,7 @@ static int _crypt_cipher_crypt(struct crypt_cipher_kernel *ctx,
 	uint32_t *type;
 	struct iovec iov = {
 		.iov_base = (void*)(uintptr_t)in,
-		.iov_len = length,
+		.iov_len = in_length,
 	};
 	int iv_msg_size = iv ? CMSG_SPACE(sizeof(*alg_iv) + iv_length) : 0;
 	char buffer[CMSG_SPACE(sizeof(*type)) + iv_msg_size];
@@ -120,7 +126,7 @@ static int _crypt_cipher_crypt(struct crypt_cipher_kernel *ctx,
 		.msg_iovlen = 1,
 	};
 
-	if (!in || !out || !length)
+	if (!in || !out || !in_length)
 		return -EINVAL;
 
 	if ((!iv && iv_length) || (iv && !iv_length))
@@ -151,13 +157,13 @@ static int _crypt_cipher_crypt(struct crypt_cipher_kernel *ctx,
 	}
 
 	len = sendmsg(ctx->opfd, &msg, 0);
-	if (len != (ssize_t)length) {
+	if (len != (ssize_t)(in_length)) {
 		r = -EIO;
 		goto bad;
 	}
 
-	len = read(ctx->opfd, out, length);
+	len = read(ctx->opfd, out, out_length);
-	if (len != (ssize_t)length)
+	if (len != (ssize_t)out_length)
 		r = -EIO;
 bad:
 	crypt_backend_memzero(buffer, sizeof(buffer));
@@ -168,7 +174,7 @@ int crypt_cipher_encrypt_kernel(struct crypt_cipher_kernel *ctx,
 				const char *in, char *out, size_t length,
 				const char *iv, size_t iv_length)
 {
-	return _crypt_cipher_crypt(ctx, in, out, length,
+	return _crypt_cipher_crypt(ctx, in, length, out, length,
 				   iv, iv_length, ALG_OP_ENCRYPT);
 }
 
@@ -176,7 +182,7 @@ int crypt_cipher_decrypt_kernel(struct crypt_cipher_kernel *ctx,
 				const char *in, char *out, size_t length,
 				const char *iv, size_t iv_length)
 {
-	return _crypt_cipher_crypt(ctx, in, out, length,
+	return _crypt_cipher_crypt(ctx, in, length, out, length,
 				   iv, iv_length, ALG_OP_DECRYPT);
 }
 
@@ -243,13 +249,56 @@ int crypt_cipher_check_kernel(const char *name, const char *mode,
 	memset(key, 0xab, key_length);
 	*key = 0xef;
 
-	r = _crypt_cipher_init(&c, key, key_length, &sa);
+	r = _crypt_cipher_init(&c, key, key_length, 0, &sa);
 	crypt_cipher_destroy_kernel(&c);
 	free(key);
 
 	return r;
 }
 
+int crypt_bitlk_decrypt_key_kernel(const void *key, size_t key_length,
+				   const char *in, char *out, size_t length,
+				   const char *iv, size_t iv_length,
+				   const char *tag, size_t tag_length)
+{
+	struct crypt_cipher_kernel c;
+	struct sockaddr_alg sa = {
+		.salg_family = AF_ALG,
+		.salg_type = "aead",
+		.salg_name = "ccm(aes)",
+	};
+	int r;
+	char buffer[128], ccm_iv[16];
+
+	if (length + tag_length > sizeof(buffer))
+		return -EINVAL;
+
+	if (iv_length > sizeof(ccm_iv) - 1)
+		return -EINVAL;
+
+	r = _crypt_cipher_init(&c, key, key_length, tag_length, &sa);
+	if (r < 0)
+		return r;
+
+	memcpy(buffer, in, length);
+	memcpy(buffer + length, tag, tag_length);
+
+	/* CCM IV - RFC3610 */
+	memset(ccm_iv, 0, sizeof(ccm_iv));
+	ccm_iv[0] = 15 - iv_length - 1;
+	memcpy(ccm_iv + 1, iv, iv_length);
+	memset(ccm_iv + 1 + iv_length, 0, ccm_iv[0] + 1);
+	iv_length = sizeof(ccm_iv);
+
+	r =  _crypt_cipher_crypt(&c, buffer, length + tag_length, out, length,
+				 ccm_iv, iv_length, ALG_OP_DECRYPT);
+
+	crypt_cipher_destroy_kernel(&c);
+	crypt_backend_memzero(buffer, sizeof(buffer));
+
+	return r;
+}
+
 #else /* ENABLE_AF_ALG */
 int crypt_cipher_init_kernel(struct crypt_cipher_kernel *ctx, const char *name,
 			     const char *mode, const void *key, size_t key_length)
@@ -280,4 +329,11 @@ int crypt_cipher_check_kernel(const char *name, const char *mode,
 	/* Cannot check, expect success. */
 	return 0;
 }
+int crypt_bitlk_decrypt_key_kernel(const void *key, size_t key_length,
+				   const char *in, char *out, size_t length,
+				   const char *iv, size_t iv_length,
+				   const char *tag, size_t tag_length)
+{
+	return -ENOTSUP;
+}
 #endif

lib/crypto_backend/crypto_kernel.c

@@ -398,5 +398,6 @@ int crypt_bitlk_decrypt_key(const void *key, size_t key_length,
 			    const char *iv, size_t iv_length,
 			    const char *tag, size_t tag_length)
 {
-	return -ENOTSUP;
+	return crypt_bitlk_decrypt_key_kernel(key, key_length, in, out, length,
+					      iv, iv_length, tag, tag_length);
 }