crypto: ecdsa - Fix NIST P521 key size reported by KEYCTL_PKEY_QUERY

When user space issues a KEYCTL_PKEY_QUERY system call for a NIST P521
key, the key_size is incorrectly reported as 528 bits instead of 521.

That's because the key size obtained through crypto_sig_keysize() is in
bytes and software_key_query() multiplies by 8 to yield the size in bits.
The underlying assumption is that the key size is always a multiple of 8.
With the recent addition of NIST P521, that's no longer the case.

Fix by returning the key_size in bits from crypto_sig_keysize() and
adjusting the calculations in software_key_query().

The ->key_size() callbacks of sig_alg algorithms now return the size in
bits, whereas the ->digest_size() and ->max_size() callbacks return the
size in bytes.  This matches with the units in struct keyctl_pkey_query.

Fixes: a7d45ba77d ("crypto: ecdsa - Register NIST P521 and extend test suite")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/asymmetric_keys/public_key.c

@@ -205,6 +205,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 			goto error_free_tfm;
 
 		len = crypto_sig_keysize(sig);
+		info->key_size = len;
 		info->max_sig_size = crypto_sig_maxsize(sig);
 		info->max_data_size = crypto_sig_digestsize(sig);
 
@@ -213,8 +214,8 @@ static int software_key_query(const struct kernel_pkey_params *params,
 			info->supported_ops |= KEYCTL_SUPPORTS_SIGN;
 
 		if (strcmp(params->encoding, "pkcs1") == 0) {
-			info->max_enc_size = len;
+			info->max_enc_size = len / BITS_PER_BYTE;
-			info->max_dec_size = len;
+			info->max_dec_size = len / BITS_PER_BYTE;
 
 			info->supported_ops |= KEYCTL_SUPPORTS_ENCRYPT;
 			if (pkey->key_is_private)
@@ -235,6 +236,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 			goto error_free_tfm;
 
 		len = crypto_akcipher_maxsize(tfm);
+		info->key_size = len * BITS_PER_BYTE;
 		info->max_sig_size = len;
 		info->max_data_size = len;
 		info->max_enc_size = len;
@@ -245,8 +247,6 @@ static int software_key_query(const struct kernel_pkey_params *params,
 			info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;
 	}
 
-	info->key_size = len * 8;
-
 	ret = 0;
 
 error_free_tfm:

crypto/ecdsa-p1363.c

@@ -21,7 +21,8 @@ static int ecdsa_p1363_verify(struct crypto_sig *tfm,
 			      const void *digest, unsigned int dlen)
 {
 	struct ecdsa_p1363_ctx *ctx = crypto_sig_ctx(tfm);
-	unsigned int keylen = crypto_sig_keysize(ctx->child);
+	unsigned int keylen = DIV_ROUND_UP_POW2(crypto_sig_keysize(ctx->child),
+						BITS_PER_BYTE);
 	unsigned int ndigits = DIV_ROUND_UP_POW2(keylen, sizeof(u64));
 	struct ecdsa_raw_sig sig;
 
@@ -45,7 +46,8 @@ static unsigned int ecdsa_p1363_max_size(struct crypto_sig *tfm)
 {
 	struct ecdsa_p1363_ctx *ctx = crypto_sig_ctx(tfm);
 
-	return 2 * crypto_sig_keysize(ctx->child);
+	return 2 * DIV_ROUND_UP_POW2(crypto_sig_keysize(ctx->child),
+				     BITS_PER_BYTE);
 }
 
 static unsigned int ecdsa_p1363_digest_size(struct crypto_sig *tfm)

crypto/ecdsa-x962.c

@@ -82,7 +82,7 @@ static int ecdsa_x962_verify(struct crypto_sig *tfm,
 	int err;
 
 	sig_ctx.ndigits = DIV_ROUND_UP_POW2(crypto_sig_keysize(ctx->child),
-					    sizeof(u64));
+					    sizeof(u64) * BITS_PER_BYTE);
 
 	err = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx, src, slen);
 	if (err < 0)
@@ -103,7 +103,8 @@ static unsigned int ecdsa_x962_max_size(struct crypto_sig *tfm)
 {
 	struct ecdsa_x962_ctx *ctx = crypto_sig_ctx(tfm);
 	struct sig_alg *alg = crypto_sig_alg(ctx->child);
-	int slen = crypto_sig_keysize(ctx->child);
+	int slen = DIV_ROUND_UP_POW2(crypto_sig_keysize(ctx->child),
+				     BITS_PER_BYTE);
 
 	/*
 	 * Verify takes ECDSA-Sig-Value (described in RFC 5480) as input,

crypto/ecdsa.c

@@ -167,7 +167,7 @@ static unsigned int ecdsa_key_size(struct crypto_sig *tfm)
 {
 	struct ecc_ctx *ctx = crypto_sig_ctx(tfm);
 
-	return DIV_ROUND_UP(ctx->curve->nbits, 8);
+	return ctx->curve->nbits;
 }
 
 static unsigned int ecdsa_digest_size(struct crypto_sig *tfm)

crypto/ecrdsa.c

@@ -249,7 +249,7 @@ static unsigned int ecrdsa_key_size(struct crypto_sig *tfm)
 	 * Verify doesn't need any output, so it's just informational
 	 * for keyctl to determine the key bit size.
 	 */
-	return ctx->pub_key.ndigits * sizeof(u64);
+	return ctx->pub_key.ndigits * sizeof(u64) * BITS_PER_BYTE;
 }
 
 static unsigned int ecrdsa_max_size(struct crypto_sig *tfm)

crypto/rsassa-pkcs1.c

@@ -301,7 +301,7 @@ static unsigned int rsassa_pkcs1_key_size(struct crypto_sig *tfm)
 {
 	struct rsassa_pkcs1_ctx *ctx = crypto_sig_ctx(tfm);
 
-	return ctx->key_size;
+	return ctx->key_size * BITS_PER_BYTE;
 }
 
 static int rsassa_pkcs1_set_pub_key(struct crypto_sig *tfm,

crypto/sig.c

@@ -102,6 +102,11 @@ static int sig_default_set_key(struct crypto_sig *tfm,
 	return -ENOSYS;
 }
 
+static unsigned int sig_default_size(struct crypto_sig *tfm)
+{
+	return DIV_ROUND_UP_POW2(crypto_sig_keysize(tfm), BITS_PER_BYTE);
+}
+
 static int sig_prepare_alg(struct sig_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;
@@ -117,9 +122,9 @@ static int sig_prepare_alg(struct sig_alg *alg)
 	if (!alg->key_size)
 		return -EINVAL;
 	if (!alg->max_size)
-		alg->max_size = alg->key_size;
+		alg->max_size = sig_default_size;
 	if (!alg->digest_size)
-		alg->digest_size = alg->key_size;
+		alg->digest_size = sig_default_size;
 
 	base->cra_type = &crypto_sig_type;
 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;

include/crypto/sig.h

@@ -128,7 +128,7 @@ static inline void crypto_free_sig(struct crypto_sig *tfm)
 /**
  * crypto_sig_keysize() - Get key size
  *
- * Function returns the key size in bytes.
+ * Function returns the key size in bits.
  * Function assumes that the key is already set in the transformation. If this
  * function is called without a setkey or with a failed setkey, you may end up
  * in a NULL dereference.