crypto: api - Add crypto_alloc_instance2

This patch adds a new argument to crypto_alloc_instance which
sets aside some space before the instance for use by algorithms
such as shash that place type-specific data before crypto_alg.

For compatibility the function has been renamed so that existing
users aren't affected.

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

2 files changed, 33 insertions, 6 deletions

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 56c62e2858d5..429f1a003b06 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -627,17 +627,20 @@ int crypto_attr_u32(struct rtattr *rta, u32 *num)
 }
 EXPORT_SYMBOL_GPL(crypto_attr_u32);
 
-struct crypto_instance *crypto_alloc_instance(const char *name,
-                                              struct crypto_alg *alg)
+void *crypto_alloc_instance2(const char *name, struct crypto_alg *alg,
+                             unsigned int head)
 {
         struct crypto_instance *inst;
-        struct crypto_spawn *spawn;
+        char *p;
         int err;
 
-        inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
-        if (!inst)
+        p = kzalloc(head + sizeof(*inst) + sizeof(struct crypto_spawn),
+                    GFP_KERNEL);
+        if (!p)
                 return ERR_PTR(-ENOMEM);
 
+        inst = (void *)(p + head);
+
         err = -ENAMETOOLONG;
         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, "%s(%s)", name,
                      alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
@@ -647,6 +650,25 @@ struct crypto_instance *crypto_alloc_instance(const char *name,
                      name, alg->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
                 goto err_free_inst;
 
+        return p;
+
+err_free_inst:
+        kfree(p);
+        return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_instance2);
+
+struct crypto_instance *crypto_alloc_instance(const char *name,
+                                              struct crypto_alg *alg)
+{
+        struct crypto_instance *inst;
+        struct crypto_spawn *spawn;
+        int err;
+
+        inst = crypto_alloc_instance2(name, alg, 0);
+        if (IS_ERR(inst))
+                goto out;
+
         spawn = crypto_instance_ctx(inst);
         err = crypto_init_spawn(spawn, alg, inst,
                                 CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
@@ -658,7 +680,10 @@ struct crypto_instance *crypto_alloc_instance(const char *name,
 
 err_free_inst:
         kfree(inst);
-        return ERR_PTR(err);
+        inst = ERR_PTR(err);
+
+out:
+        return inst;
 }
 EXPORT_SYMBOL_GPL(crypto_alloc_instance);
 
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index ce010a346420..99bb29723130 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -132,6 +132,8 @@ int crypto_check_attr_type(struct rtattr **tb, u32 type);
 const char *crypto_attr_alg_name(struct rtattr *rta);
 struct crypto_alg *crypto_attr_alg(struct rtattr *rta, u32 type, u32 mask);
 int crypto_attr_u32(struct rtattr *rta, u32 *num);
+void *crypto_alloc_instance2(const char *name, struct crypto_alg *alg,
+                             unsigned int head);
 struct crypto_instance *crypto_alloc_instance(const char *name,
                                               struct crypto_alg *alg);