[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>

1 files changed, 157 insertions, 1 deletions

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 092d965..d1df528 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");