crypto: rsa - RSA padding algorithm

This patch adds PKCS#1 v1.5 standard RSA padding as a separate template.
This way an RSA cipher with padding can be obtained by instantiating
"pkcs1pad(rsa)".  The reason for adding this is that RSA is almost
never used without this padding (or OAEP) so it will be needed for
either certificate work in the kernel or the userspace, and I also hear
that it is likely implemented by hardware RSA in which case hardware
implementations of the whole of pkcs1pad(rsa) can be provided.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/Makefile

@@ -40,6 +40,7 @@ rsa_generic-y := rsapubkey-asn1.o
 rsa_generic-y += rsaprivkey-asn1.o
 rsa_generic-y += rsa.o
 rsa_generic-y += rsa_helper.o
+rsa_generic-y += rsa-pkcs1pad.o
 obj-$(CONFIG_CRYPTO_RSA) += rsa_generic.o
 
 cryptomgr-y := algboss.o testmgr.o

crypto/rsa.c

@@ -13,6 +13,7 @@
 #include <crypto/internal/rsa.h>
 #include <crypto/internal/akcipher.h>
 #include <crypto/akcipher.h>
+#include <crypto/algapi.h>
 
 /*
  * RSAEP function [RFC3447 sec 5.1.1]
@@ -315,11 +316,24 @@ static struct akcipher_alg rsa = {
 
 static int rsa_init(void)
 {
-	return crypto_register_akcipher(&rsa);
+	int err;
+
+	err = crypto_register_akcipher(&rsa);
+	if (err)
+		return err;
+
+	err = crypto_register_template(&rsa_pkcs1pad_tmpl);
+	if (err) {
+		crypto_unregister_akcipher(&rsa);
+		return err;
+	}
+
+	return 0;
 }
 
 static void rsa_exit(void)
 {
+	crypto_unregister_template(&rsa_pkcs1pad_tmpl);
 	crypto_unregister_akcipher(&rsa);
 }
 

include/crypto/internal/rsa.h

@@ -27,4 +27,6 @@ int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
 		       unsigned int key_len);
 
 void rsa_free_key(struct rsa_key *rsa_key);
+
+extern struct crypto_template rsa_pkcs1pad_tmpl;
 #endif