crypto: ecdsa - Add support for ECDSA signature verification

Add support for parsing the parameters of a NIST P256 or NIST P192 key.
Enable signature verification using these keys. The new module is
enabled with CONFIG_ECDSA:
  Elliptic Curve Digital Signature Algorithm (NIST P192, P256 etc.)
  is A NIST cryptographic standard algorithm. Only signature verification
  is implemented.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/Kconfig

@@ -242,6 +242,16 @@ config CRYPTO_ECDH
 	help
 	  Generic implementation of the ECDH algorithm
 
+config CRYPTO_ECDSA
+	tristate "ECDSA (NIST P192, P256 etc.) algorithm"
+	select CRYPTO_ECC
+	select CRYPTO_AKCIPHER
+	select ASN1
+	help
+	  Elliptic Curve Digital Signature Algorithm (NIST P192, P256 etc.)
+	  is A NIST cryptographic standard algorithm. Only signature verification
+	  is implemented.
+
 config CRYPTO_ECRDSA
 	tristate "EC-RDSA (GOST 34.10) algorithm"
 	select CRYPTO_ECC

crypto/Makefile

@@ -50,6 +50,12 @@ sm2_generic-y += sm2.o
 
 obj-$(CONFIG_CRYPTO_SM2) += sm2_generic.o
 
+$(obj)/ecdsasignature.asn1.o: $(obj)/ecdsasignature.asn1.c $(obj)/ecdsasignature.asn1.h
+$(obj)/ecdsa.o: $(obj)/ecdsasignature.asn1.h
+ecdsa_generic-y += ecdsa.o
+ecdsa_generic-y += ecdsasignature.asn1.o
+obj-$(CONFIG_CRYPTO_ECDSA) += ecdsa_generic.o
+
 crypto_acompress-y := acompress.o
 crypto_acompress-y += scompress.o
 obj-$(CONFIG_CRYPTO_ACOMP2) += crypto_acompress.o

crypto/ecc.c

@@ -42,7 +42,7 @@ typedef struct {
 	u64 m_high;
 } uint128_t;
 
-static inline const struct ecc_curve *ecc_get_curve(unsigned int curve_id)
+const struct ecc_curve *ecc_get_curve(unsigned int curve_id)
 {
 	switch (curve_id) {
 	/* In FIPS mode only allow P256 and higher */
@@ -54,6 +54,7 @@ static inline const struct ecc_curve *ecc_get_curve(unsigned int curve_id)
 		return NULL;
 	}
 }
+EXPORT_SYMBOL(ecc_get_curve);
 
 static u64 *ecc_alloc_digits_space(unsigned int ndigits)
 {
@@ -1281,16 +1282,6 @@ void ecc_point_mult_shamir(const struct ecc_point *result,
 }
 EXPORT_SYMBOL(ecc_point_mult_shamir);
 
-static inline void ecc_swap_digits(const u64 *in, u64 *out,
-				   unsigned int ndigits)
-{
-	const __be64 *src = (__force __be64 *)in;
-	int i;
-
-	for (i = 0; i < ndigits; i++)
-		out[i] = be64_to_cpu(src[ndigits - 1 - i]);
-}
-
 static int __ecc_is_key_valid(const struct ecc_curve *curve,
 			      const u64 *private_key, unsigned int ndigits)
 {

crypto/ecc.h

@@ -33,6 +33,8 @@
 
 #define ECC_DIGITS_TO_BYTES_SHIFT 3
 
+#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
+
 /**
  * struct ecc_point - elliptic curve point in affine coordinates
  *
@@ -70,6 +72,29 @@ struct ecc_curve {
 	u64 *b;
 };
 
+/**
+ * ecc_swap_digits() - Copy ndigits from big endian array to native array
+ * @in:       Input array
+ * @out:      Output array
+ * @ndigits:  Number of digits to copy
+ */
+static inline void ecc_swap_digits(const u64 *in, u64 *out, unsigned int ndigits)
+{
+	const __be64 *src = (__force __be64 *)in;
+	int i;
+
+	for (i = 0; i < ndigits; i++)
+		out[i] = be64_to_cpu(src[ndigits - 1 - i]);
+}
+
+/**
+ * ecc_get_curve()  - Get a curve given its curve_id
+ * @curve_id:  Id of the curve
+ *
+ * Returns pointer to the curve data, NULL if curve is not available
+ */
+const struct ecc_curve *ecc_get_curve(unsigned int curve_id);
+
 /**
  * ecc_is_key_valid() - Validate a given ECDH private key
  *