[CRYPTO] skcipher: Create default givcipher instances

This patch makes crypto_alloc_ablkcipher/crypto_grab_skcipher always
return algorithms that are capable of generating their own IVs through
givencrypt and givdecrypt.  Each algorithm may specify its default IV
generator through the geniv field.

For algorithms that do not set the geniv field, the blkcipher layer will
pick a default.  Currently it's chainiv for synchronous algorithms and
eseqiv for asynchronous algorithms.  Note that if these wrappers do not
work on an algorithm then that algorithm must specify its own geniv or
it can't be used at all.

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

4 files changed, 177 insertions, 6 deletions

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 092d9659b86..d1df528c8fa 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -18,6 +18,8 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/rtnetlink.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 
@@ -68,6 +70,16 @@ static unsigned int crypto_ablkcipher_ctxsize(struct crypto_alg *alg, u32 type,
 	return alg->cra_ctxsize;
 }
 
+int skcipher_null_givencrypt(struct skcipher_givcrypt_request *req)
+{
+	return crypto_ablkcipher_encrypt(&req->creq);
+}
+
+int skcipher_null_givdecrypt(struct skcipher_givcrypt_request *req)
+{
+	return crypto_ablkcipher_decrypt(&req->creq);
+}
+
 static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
 				      u32 mask)
 {
@@ -80,6 +92,10 @@ static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
 	crt->setkey = setkey;
 	crt->encrypt = alg->encrypt;
 	crt->decrypt = alg->decrypt;
+	if (!alg->ivsize) {
+		crt->givencrypt = skcipher_null_givencrypt;
+		crt->givdecrypt = skcipher_null_givdecrypt;
+	}
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;
 
@@ -163,6 +179,108 @@ const char *crypto_default_geniv(const struct crypto_alg *alg)
 	return alg->cra_flags & CRYPTO_ALG_ASYNC ? "eseqiv" : "chainiv";
 }
 
+static int crypto_givcipher_default(struct crypto_alg *alg, u32 type, u32 mask)
+{
+	struct rtattr *tb[3];
+	struct {
+		struct rtattr attr;
+		struct crypto_attr_type data;
+	} ptype;
+	struct {
+		struct rtattr attr;
+		struct crypto_attr_alg data;
+	} palg;
+	struct crypto_template *tmpl;
+	struct crypto_instance *inst;
+	struct crypto_alg *larval;
+	const char *geniv;
+	int err;
+
+	larval = crypto_larval_lookup(alg->cra_driver_name,
+				      CRYPTO_ALG_TYPE_GIVCIPHER,
+				      CRYPTO_ALG_TYPE_MASK);
+	err = PTR_ERR(larval);
+	if (IS_ERR(larval))
+		goto out;
+
+	err = -EAGAIN;
+	if (!crypto_is_larval(larval))
+		goto drop_larval;
+
+	ptype.attr.rta_len = sizeof(ptype);
+	ptype.attr.rta_type = CRYPTOA_TYPE;
+	ptype.data.type = type | CRYPTO_ALG_GENIV;
+	/* GENIV tells the template that we're making a default geniv. */
+	ptype.data.mask = mask | CRYPTO_ALG_GENIV;
+	tb[0] = &ptype.attr;
+
+	palg.attr.rta_len = sizeof(palg);
+	palg.attr.rta_type = CRYPTOA_ALG;
+	/* Must use the exact name to locate ourselves. */
+	memcpy(palg.data.name, alg->cra_driver_name, CRYPTO_MAX_ALG_NAME);
+	tb[1] = &palg.attr;
+
+	tb[2] = NULL;
+
+	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+	    CRYPTO_ALG_TYPE_BLKCIPHER)
+		geniv = alg->cra_blkcipher.geniv;
+	else
+		geniv = alg->cra_ablkcipher.geniv;
+
+	if (!geniv)
+		geniv = crypto_default_geniv(alg);
+
+	tmpl = crypto_lookup_template(geniv);
+	err = -ENOENT;
+	if (!tmpl)
+		goto kill_larval;
+
+	inst = tmpl->alloc(tb);
+	err = PTR_ERR(inst);
+	if (IS_ERR(inst))
+		goto put_tmpl;
+
+	if ((err = crypto_register_instance(tmpl, inst))) {
+		tmpl->free(inst);
+		goto put_tmpl;
+	}
+
+	/* Redo the lookup to use the instance we just registered. */
+	err = -EAGAIN;
+
+put_tmpl:
+	crypto_tmpl_put(tmpl);
+kill_larval:
+	crypto_larval_kill(larval);
+drop_larval:
+	crypto_mod_put(larval);
+out:
+	crypto_mod_put(alg);
+	return err;
+}
+
+static struct crypto_alg *crypto_lookup_skcipher(const char *name, u32 type,
+						 u32 mask)
+{
+	struct crypto_alg *alg;
+
+	alg = crypto_alg_mod_lookup(name, type, mask);
+	if (IS_ERR(alg))
+		return alg;
+
+	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+	    CRYPTO_ALG_TYPE_GIVCIPHER)
+		return alg;
+
+	if (!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+	      CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
+					  alg->cra_ablkcipher.ivsize))
+		return alg;
+
+	return ERR_PTR(crypto_givcipher_default(alg, type, mask));
+}
+
 int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
 			 u32 type, u32 mask)
 {
@@ -172,7 +290,7 @@ int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
 	type = crypto_skcipher_type(type);
 	mask = crypto_skcipher_mask(mask);
 
-	alg = crypto_alg_mod_lookup(name, type, mask);
+	alg = crypto_lookup_skcipher(name, type, mask);
 	if (IS_ERR(alg))
 		return PTR_ERR(alg);
 
@@ -182,5 +300,43 @@ int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
 }
 EXPORT_SYMBOL_GPL(crypto_grab_skcipher);
 
+struct crypto_ablkcipher *crypto_alloc_ablkcipher(const char *alg_name,
+						  u32 type, u32 mask)
+{
+	struct crypto_tfm *tfm;
+	int err;
+
+	type = crypto_skcipher_type(type);
+	mask = crypto_skcipher_mask(mask);
+
+	for (;;) {
+		struct crypto_alg *alg;
+
+		alg = crypto_lookup_skcipher(alg_name, type, mask);
+		if (IS_ERR(alg)) {
+			err = PTR_ERR(alg);
+			goto err;
+		}
+
+		tfm = __crypto_alloc_tfm(alg, type, mask);
+		if (!IS_ERR(tfm))
+			return __crypto_ablkcipher_cast(tfm);
+
+		crypto_mod_put(alg);
+		err = PTR_ERR(tfm);
+
+err:
+		if (err != -EAGAIN)
+			break;
+		if (signal_pending(current)) {
+			err = -EINTR;
+			break;
+		}
+	}
+
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_ablkcipher);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Asynchronous block chaining cipher type");
diff --git a/crypto/api.c b/crypto/api.c
index 1f5c7247735..a2496d1bc6d 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -137,7 +137,7 @@ static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
 	return alg;
 }
 
-static void crypto_larval_kill(struct crypto_alg *alg)
+void crypto_larval_kill(struct crypto_alg *alg)
 {
 	struct crypto_larval *larval = (void *)alg;
 
@@ -147,6 +147,7 @@ static void crypto_larval_kill(struct crypto_alg *alg)
 	complete_all(&larval->completion);
 	crypto_alg_put(alg);
 }
+EXPORT_SYMBOL_GPL(crypto_larval_kill);
 
 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 {
@@ -176,11 +177,9 @@ static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 	return alg;
 }
 
-struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
+struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
 {
 	struct crypto_alg *alg;
-	struct crypto_alg *larval;
-	int ok;
 
 	if (!name)
 		return ERR_PTR(-ENOENT);
@@ -193,7 +192,17 @@ struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 	if (alg)
 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 
-	larval = crypto_larval_alloc(name, type, mask);
+	return crypto_larval_alloc(name, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_larval_lookup);
+
+struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
+{
+	struct crypto_alg *alg;
+	struct crypto_alg *larval;
+	int ok;
+
+	larval = crypto_larval_lookup(name, type, mask);
 	if (IS_ERR(larval) || !crypto_is_larval(larval))
 		return larval;
 
diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index ca6ef065cde..4a7e65c4df4 100644
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -450,6 +450,10 @@ static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
 	crt->setkey = async_setkey;
 	crt->encrypt = async_encrypt;
 	crt->decrypt = async_decrypt;
+	if (!alg->ivsize) {
+		crt->givencrypt = skcipher_null_givencrypt;
+		crt->givdecrypt = skcipher_null_givdecrypt;
+	}
 	crt->base = __crypto_ablkcipher_cast(tfm);
 	crt->ivsize = alg->ivsize;
 
diff --git a/crypto/internal.h b/crypto/internal.h
index cb13952f82b..32f4c214560 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -93,6 +93,8 @@ void crypto_exit_digest_ops(struct crypto_tfm *tfm);
 void crypto_exit_cipher_ops(struct crypto_tfm *tfm);
 void crypto_exit_compress_ops(struct crypto_tfm *tfm);
 
+void crypto_larval_kill(struct crypto_alg *alg);
+struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask);
 void crypto_larval_error(const char *name, u32 type, u32 mask);
 
 void crypto_shoot_alg(struct crypto_alg *alg);