[CRYPTO] skcipher: Add crypto_grab_skcipher interface

Note: From now on the collective of ablkcipher/blkcipher/givcipher will
be known as skcipher, i.e., symmetric key cipher.  The name blkcipher has
always been much of a misnomer since it supports stream ciphers too.

This patch adds the function crypto_grab_skcipher as a new way of getting
an ablkcipher spawn.  The problem is that previously we did this in two
steps, first getting the algorithm and then calling crypto_init_spawn.

This meant that each spawn user had to be aware of what type and mask to
use for these two steps.  This is difficult and also presents a problem
when the type/mask changes as they're about to be for IV generators.

The new interface does both steps together just like crypto_alloc_ablkcipher.

As a side-effect this also allows us to be stronger on type enforcement
for spawns.  For now this is only done for ablkcipher but it's trivial
to extend for other types.

This patch also moves the type/mask logic for skcipher into the helpers
crypto_skcipher_type and crypto_skcipher_mask.

Finally this patch introduces the function crypto_require_sync to determine
whether the user is specifically requesting a sync algorithm.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

4 files changed, 108 insertions, 16 deletions

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 2731acb..0083140 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -13,14 +13,16 @@
  *
  */
 
-#include <crypto/algapi.h>
-#include <linux/errno.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 
+#include "internal.h"
+
 static int setkey_unaligned(struct crypto_ablkcipher *tfm, const u8 *key,
 			    unsigned int keylen)
 {
@@ -105,5 +107,24 @@ const struct crypto_type crypto_ablkcipher_type = {
 };
 EXPORT_SYMBOL_GPL(crypto_ablkcipher_type);
 
+int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
+			 u32 type, u32 mask)
+{
+	struct crypto_alg *alg;
+	int err;
+
+	type = crypto_skcipher_type(type);
+	mask = crypto_skcipher_mask(mask);
+
+	alg = crypto_alg_mod_lookup(name, type, mask);
+	if (IS_ERR(alg))
+		return PTR_ERR(alg);
+
+	err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
+	crypto_mod_put(alg);
+	return err;
+}
+EXPORT_SYMBOL_GPL(crypto_grab_skcipher);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Asynchronous block chaining cipher type");
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 726a765..fda1759 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -111,6 +111,12 @@ void crypto_drop_spawn(struct crypto_spawn *spawn);
 struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type,
 				    u32 mask);
 
+static inline void crypto_set_spawn(struct crypto_spawn *spawn,
+				    struct crypto_instance *inst)
+{
+	spawn->inst = inst;
+}
+
 struct crypto_attr_type *crypto_get_attr_type(struct rtattr **tb);
 int crypto_check_attr_type(struct rtattr **tb, u32 type);
 const char *crypto_attr_alg_name(struct rtattr *rta);
@@ -195,10 +201,9 @@ static inline struct crypto_instance *crypto_aead_alg_instance(
 static inline struct crypto_ablkcipher *crypto_spawn_ablkcipher(
 	struct crypto_spawn *spawn)
 {
-	u32 type = CRYPTO_ALG_TYPE_BLKCIPHER;
-	u32 mask = CRYPTO_ALG_TYPE_BLKCIPHER_MASK;
-
-	return __crypto_ablkcipher_cast(crypto_spawn_tfm(spawn, type, mask));
+	return __crypto_ablkcipher_cast(
+		crypto_spawn_tfm(spawn, crypto_skcipher_type(0),
+				 crypto_skcipher_mask(0)));
 }
 
 static inline struct crypto_blkcipher *crypto_spawn_blkcipher(
@@ -308,5 +313,14 @@ static inline struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb,
 	return crypto_attr_alg(tb[1], type, mask);
 }
 
+/*
+ * Returns CRYPTO_ALG_ASYNC if type/mask requires the use of sync algorithms.
+ * Otherwise returns zero.
+ */
+static inline int crypto_requires_sync(u32 type, u32 mask)
+{
+	return (type ^ CRYPTO_ALG_ASYNC) & mask & CRYPTO_ALG_ASYNC;
+}
+
 #endif	/* _CRYPTO_ALGAPI_H */
 
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
new file mode 100644
index 0000000..87879e6
--- /dev/null
+++ b/include/crypto/internal/skcipher.h
@@ -0,0 +1,51 @@
+/*
+ * Symmetric key ciphers.
+ * 
+ * Copyright (c) 2007 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.
+ *
+ */
+
+#ifndef _CRYPTO_INTERNAL_SKCIPHER_H
+#define _CRYPTO_INTERNAL_SKCIPHER_H
+
+#include <crypto/algapi.h>
+
+struct crypto_skcipher_spawn {
+	struct crypto_spawn base;
+};
+
+static inline void crypto_set_skcipher_spawn(
+	struct crypto_skcipher_spawn *spawn, struct crypto_instance *inst)
+{
+	crypto_set_spawn(&spawn->base, inst);
+}
+
+int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
+			 u32 type, u32 mask);
+
+static inline void crypto_drop_skcipher(struct crypto_skcipher_spawn *spawn)
+{
+	crypto_drop_spawn(&spawn->base);
+}
+
+static inline struct crypto_alg *crypto_skcipher_spawn_alg(
+	struct crypto_skcipher_spawn *spawn)
+{
+	return spawn->base.alg;
+}
+
+static inline struct crypto_ablkcipher *crypto_spawn_skcipher(
+	struct crypto_skcipher_spawn *spawn)
+{
+	return __crypto_ablkcipher_cast(
+		crypto_spawn_tfm(&spawn->base, crypto_skcipher_type(0),
+				 crypto_skcipher_mask(0)));
+}
+
+#endif	/* _CRYPTO_INTERNAL_SKCIPHER_H */
+
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index ef7642e..d6962b4 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -528,16 +528,26 @@ static inline struct crypto_ablkcipher *__crypto_ablkcipher_cast(
 	return (struct crypto_ablkcipher *)tfm;
 }
 
-static inline struct crypto_ablkcipher *crypto_alloc_ablkcipher(
-	const char *alg_name, u32 type, u32 mask)
+static inline u32 crypto_skcipher_type(u32 type)
 {
 	type &= ~CRYPTO_ALG_TYPE_MASK;
-	mask &= ~CRYPTO_ALG_TYPE_MASK;
 	type |= CRYPTO_ALG_TYPE_BLKCIPHER;
+	return type;
+}
+
+static inline u32 crypto_skcipher_mask(u32 mask)
+{
+	mask &= ~CRYPTO_ALG_TYPE_MASK;
 	mask |= CRYPTO_ALG_TYPE_BLKCIPHER_MASK;
+	return mask;
+}
 
+static inline struct crypto_ablkcipher *crypto_alloc_ablkcipher(
+	const char *alg_name, u32 type, u32 mask)
+{
 	return __crypto_ablkcipher_cast(
-		crypto_alloc_base(alg_name, type, mask));
+		crypto_alloc_base(alg_name, crypto_skcipher_type(type),
+				  crypto_skcipher_mask(mask)));
 }
 
 static inline struct crypto_tfm *crypto_ablkcipher_tfm(
@@ -554,12 +564,8 @@ static inline void crypto_free_ablkcipher(struct crypto_ablkcipher *tfm)
 static inline int crypto_has_ablkcipher(const char *alg_name, u32 type,
 					u32 mask)
 {
-	type &= ~CRYPTO_ALG_TYPE_MASK;
-	mask &= ~CRYPTO_ALG_TYPE_MASK;
-	type |= CRYPTO_ALG_TYPE_BLKCIPHER;
-	mask |= CRYPTO_ALG_TYPE_BLKCIPHER_MASK;
-
-	return crypto_has_alg(alg_name, type, mask);
+	return crypto_has_alg(alg_name, crypto_skcipher_type(type),
+			      crypto_skcipher_mask(mask));
 }
 
 static inline struct ablkcipher_tfm *crypto_ablkcipher_crt(