[CRYPTO] api: Add cryptomgr

The cryptomgr module is a simple manager of crypto algorithm instances.
It ensures that parameterised algorithms of the type tmpl(alg) (e.g.,
cbc(aes)) are always created.

This is meant to satisfy the needs for most users.  For more complex
cases such as deeper combinations or multiple parameters, a netlink
module will be created which allows arbitrary expressions to be parsed
in user-space.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

crypto/Kconfig

@@ -16,6 +16,14 @@ config CRYPTO_ALGAPI
 	help
 	  This option provides the API for cryptographic algorithms.
 
+config CRYPTO_MANAGER
+	tristate "Cryptographic algorithm manager"
+	select CRYPTO_ALGAPI
+	default m
+	help
+	  Create default cryptographic template instantiations such as
+	  cbc(aes).
+
 config CRYPTO_HMAC
 	bool "HMAC support"
 	help

crypto/Makefile

@@ -8,6 +8,7 @@ crypto_algapi-$(CONFIG_PROC_FS) += proc.o
 crypto_algapi-objs := algapi.o $(crypto_algapi-y)
 obj-$(CONFIG_CRYPTO_ALGAPI) += crypto_algapi.o
 
+obj-$(CONFIG_CRYPTO_MANAGER) += cryptomgr.o
 obj-$(CONFIG_CRYPTO_HMAC) += hmac.o
 obj-$(CONFIG_CRYPTO_NULL) += crypto_null.o
 obj-$(CONFIG_CRYPTO_MD4) += md4.o

crypto/api.c

@@ -18,6 +18,7 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/kmod.h>
+#include <linux/module.h>
 #include <linux/param.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -170,6 +171,7 @@ static struct crypto_alg *crypto_alg_mod_lookup(const char *name)
 {
 	struct crypto_alg *alg;
 	struct crypto_alg *larval;
+	int ok;
 
 	alg = try_then_request_module(crypto_alg_lookup(name), name);
 	if (alg)
@@ -179,7 +181,13 @@ static struct crypto_alg *crypto_alg_mod_lookup(const char *name)
 	if (!larval || !crypto_is_larval(larval))
 		return larval;
 
-	if (crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval) == NOTIFY_STOP)
+	ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
+	if (ok == NOTIFY_DONE) {
+		request_module("cryptomgr");
+		ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
+	}
+
+	if (ok == NOTIFY_STOP)
 		alg = crypto_larval_wait(larval);
 	else {
 		crypto_mod_put(larval);

crypto/cryptomgr.c

+/*
+ * Create default crypto algorithm instances.
+ *
+ * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <linux/crypto.h>
+#include <linux/ctype.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/rtnetlink.h>
+#include <linux/string.h>
+#include <linux/workqueue.h>
+
+#include "internal.h"
+
+struct cryptomgr_param {
+	struct work_struct work;
+
+	struct {
+		struct rtattr attr;
+		struct crypto_attr_alg data;
+	} alg;
+
+	struct {
+		char name[CRYPTO_MAX_ALG_NAME];
+	} larval;
+
+	char template[CRYPTO_MAX_ALG_NAME];
+};
+
+static void cryptomgr_probe(void *data)
+{
+	struct cryptomgr_param *param = data;
+	struct crypto_template *tmpl;
+	struct crypto_instance *inst;
+
+	tmpl = crypto_lookup_template(param->template);
+	if (!tmpl)
+		goto err;
+
+	inst = tmpl->alloc(&param->alg, sizeof(param->alg));
+	if (IS_ERR(inst))
+		goto err;
+	else if ((err = crypto_register_instance(tmpl, inst))) {
+		tmpl->free(inst);
+		goto err;
+	}
+
+	crypto_tmpl_put(tmpl);
+
+out:
+	kfree(param);
+	return;
+
+err:
+	crypto_larval_error(param->larval.name);
+	goto out;
+}
+
+static int cryptomgr_schedule_probe(struct crypto_larval *larval)
+{
+	struct cryptomgr_param *param;
+	const char *name = larval->alg.cra_name;
+	const char *p;
+	unsigned int len;
+
+	param = kmalloc(sizeof(*param), GFP_KERNEL);
+	if (!param)
+		goto err;
+
+	for (p = name; isalnum(*p) || *p == '-' || *p == '_'; p++)
+		;
+
+	len = p - name;
+	if (!len || *p != '(')
+		goto err_free_param;
+
+	memcpy(param->template, name, len);
+	param->template[len] = 0;
+
+	name = p + 1;
+	for (p = name; isalnum(*p) || *p == '-' || *p == '_'; p++)
+		;
+
+	len = p - name;
+	if (!len || *p != ')' || p[1])
+		goto err_free_param;
+
+	param->alg.attr.rta_len = sizeof(param->alg);
+	param->alg.attr.rta_type = CRYPTOA_ALG;
+	memcpy(param->alg.data.name, name, len);
+	param->alg.data.name[len] = 0;
+
+	memcpy(param->larval.name, larval->alg.cra_name, CRYPTO_MAX_ALG_NAME);
+
+	INIT_WORK(&param->work, cryptomgr_probe, param);
+	schedule_work(&param->work);
+
+	return NOTIFY_STOP;
+
+err_free_param:
+	kfree(param);
+err:
+	return NOTIFY_OK;
+}
+
+static int cryptomgr_notify(struct notifier_block *this, unsigned long msg,
+			    void *data)
+{
+	switch (msg) {
+	case CRYPTO_MSG_ALG_REQUEST:
+		return cryptomgr_schedule_probe(data);
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block cryptomgr_notifier = {
+	.notifier_call = cryptomgr_notify,
+};
+
+static int __init cryptomgr_init(void)
+{
+	return crypto_register_notifier(&cryptomgr_notifier);
+}
+
+static void __exit cryptomgr_exit(void)
+{
+	int err = crypto_unregister_notifier(&cryptomgr_notifier);
+	BUG_ON(err);
+}
+
+module_init(cryptomgr_init);
+module_exit(cryptomgr_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Crypto Algorithm Manager");

include/linux/crypto.h

@@ -260,6 +260,15 @@ struct crypto_tfm {
 	void *__crt_ctx[] CRYPTO_MINALIGN_ATTR;
 };
 
+enum {
+	CRYPTOA_UNSPEC,
+	CRYPTOA_ALG,
+};
+
+struct crypto_attr_alg {
+	char name[CRYPTO_MAX_ALG_NAME];
+};
+
 /* 
  * Transform user interface.
  */