[CRYPTO]: Add crypto_alg_available interface.

crypto/api.c

@@ -100,13 +100,7 @@ struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 	struct crypto_tfm *tfm = NULL;
 	struct crypto_alg *alg;
 
-	alg = crypto_alg_lookup(name);
-#ifdef CONFIG_KMOD
-	if (alg == NULL) {
-		crypto_alg_autoload(name);
-		alg = crypto_alg_lookup(name);
-	}
-#endif
+	alg = crypto_alg_mod_lookup(name);
 	if (alg == NULL)
 		goto out;
 	
@@ -208,6 +202,19 @@ int crypto_unregister_alg(struct crypto_alg *alg)
 	return ret;
 }
 
+int crypto_alg_available(const char *name, u32 flags)
+{
+	int ret = 0;
+	struct crypto_alg *alg = crypto_alg_mod_lookup(name);
+	
+	if (alg) {
+		crypto_alg_put(alg);
+		ret = 1;
+	}
+	
+	return ret;
+}
+
 static void *c_start(struct seq_file *m, loff_t *pos)
 {
 	struct list_head *v;
@@ -297,3 +304,4 @@ EXPORT_SYMBOL_GPL(crypto_register_alg);
 EXPORT_SYMBOL_GPL(crypto_unregister_alg);
 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
 EXPORT_SYMBOL_GPL(crypto_free_tfm);
+EXPORT_SYMBOL_GPL(crypto_alg_available);

crypto/autoload.c

@@ -25,3 +25,13 @@ void crypto_alg_autoload(const char *name)
 {
 	request_module(name);
 }
+
+struct crypto_alg *crypto_alg_mod_lookup(const char *name)
+{
+	struct crypto_alg *alg = crypto_alg_lookup(name);
+	if (alg == NULL) {
+		crypto_alg_autoload(name);
+		alg = crypto_alg_lookup(name);
+	}
+	return alg;
+}

crypto/internal.h

@@ -40,8 +40,16 @@ static inline u32 crypto_cipher_flags(u32 flags)
 	return flags & (CRYPTO_TFM_MODE_MASK|CRYPTO_TFM_REQ_WEAK_KEY);
 }
 
+struct crypto_alg *crypto_alg_lookup(const char *name);
+
 #ifdef CONFIG_KMOD
 void crypto_alg_autoload(const char *name);
+struct crypto_alg *crypto_alg_mod_lookup(const char *name);
+#else
+static inline struct crypto_alg *crypto_alg_mod_lookup(const char *name)
+{
+	return crypto_alg_lookup(name);
+}
 #endif
 
 int crypto_init_digest_flags(struct crypto_tfm *tfm, u32 flags);

crypto/tcrypt.c

@@ -46,6 +46,8 @@ static int mode = 0;
 static char *xbuf;
 static char *tvmem;
 
+static char *check[] = { "des", "md5", "des3_ede", "rot13", "sha1", NULL };
+
 static void
 hexdump(unsigned char *buf, unsigned int len)
 {
@@ -1299,6 +1301,19 @@ test_des3_ede(void)
 	crypto_free_tfm(tfm);
 }
 
+static void
+test_available(void)
+{
+	char **name = check;
+	
+	while (*name) {
+		printk("alg %s ", *name);
+		printk((crypto_alg_available(*name, 0)) ?
+			"found\n" : "not found\n");
+		name++;
+	}	
+}
+
 static void
 do_test(void)
 {
@@ -1332,6 +1347,10 @@ do_test(void)
 		test_md4();
 		break;
 
+	case 100:
+		test_available();
+		break;
+		
 	default:
 		/* useful for debugging */
 		printk("not testing anything\n");

include/linux/crypto.h

@@ -111,6 +111,11 @@ struct crypto_alg {
 int crypto_register_alg(struct crypto_alg *alg);
 int crypto_unregister_alg(struct crypto_alg *alg);
 
+/*
+ * Algorithm query interface.
+ */
+int crypto_alg_available(const char *name, u32 flags);
+
 /*
  * Transforms: user-instantiated objects which encapsulate algorithms
  * and core processing logic.  Managed via crypto_alloc_tfm() and