[CRYPTO] api: Added spawns

Spawns lock a specific crypto algorithm in place.  They can then be used
with crypto_spawn_tfm to allocate a tfm for that algorithm.  When the base
algorithm of a spawn is deregistered, all its spawns will be automatically
removed.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 169 insertions, 16 deletions

diff --git a/crypto/algapi.c b/crypto/algapi.c
index acea250677c0..36c4f1bdb521 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -10,6 +10,7 @@
  *
  */
 
+#include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -73,27 +74,96 @@ static int crypto_check_alg(struct crypto_alg *alg)
         return crypto_set_driver_name(alg);
 }
 
-static int __crypto_register_alg(struct crypto_alg *alg)
+static void crypto_destroy_instance(struct crypto_alg *alg)
+{
+        struct crypto_instance *inst = (void *)alg;
+        struct crypto_template *tmpl = inst->tmpl;
+
+        tmpl->free(inst);
+        crypto_tmpl_put(tmpl);
+}
+
+static void crypto_remove_spawns(struct list_head *spawns,
+                                 struct list_head *list)
+{
+        struct crypto_spawn *spawn, *n;
+
+        list_for_each_entry_safe(spawn, n, spawns, list) {
+                struct crypto_instance *inst = spawn->inst;
+                struct crypto_template *tmpl = inst->tmpl;
+
+                list_del_init(&spawn->list);
+                spawn->alg = NULL;
+
+                if (crypto_is_dead(&inst->alg))
+                        continue;
+
+                inst->alg.cra_flags |= CRYPTO_ALG_DEAD;
+                if (!tmpl || !crypto_tmpl_get(tmpl))
+                        continue;
+
+                crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, &inst->alg);
+                list_move(&inst->alg.cra_list, list);
+                hlist_del(&inst->list);
+                inst->alg.cra_destroy = crypto_destroy_instance;
+
+                if (!list_empty(&inst->alg.cra_users)) {
+                        if (&n->list == spawns)
+                                n = list_entry(inst->alg.cra_users.next,
+                                               typeof(*n), list);
+                        __list_splice(&inst->alg.cra_users, spawns->prev);
+                }
+        }
+}
+
+static int __crypto_register_alg(struct crypto_alg *alg,
+                                 struct list_head *list)
 {
         struct crypto_alg *q;
-        int ret = -EEXIST;
+        int ret = -EAGAIN;
+
+        if (crypto_is_dead(alg))
+                goto out;
+
+        INIT_LIST_HEAD(&alg->cra_users);
+
+        ret = -EEXIST;
 
         atomic_set(&alg->cra_refcnt, 1);
         list_for_each_entry(q, &crypto_alg_list, cra_list) {
                 if (q == alg)
                         goto out;
-                if (crypto_is_larval(q) &&
-                    (!strcmp(alg->cra_name, q->cra_name) ||
-                     !strcmp(alg->cra_driver_name, q->cra_name))) {
+
+                if (crypto_is_moribund(q))
+                        continue;
+
+                if (crypto_is_larval(q)) {
                         struct crypto_larval *larval = (void *)q;
 
+                        if (strcmp(alg->cra_name, q->cra_name) &&
+                            strcmp(alg->cra_driver_name, q->cra_name))
+                                continue;
+
+                        if (larval->adult)
+                                continue;
                         if ((q->cra_flags ^ alg->cra_flags) & larval->mask)
                                 continue;
                         if (!crypto_mod_get(alg))
                                 continue;
+
                         larval->adult = alg;
                         complete(&larval->completion);
+                        continue;
                 }
+
+                if (strcmp(alg->cra_name, q->cra_name))
+                        continue;
+
+                if (strcmp(alg->cra_driver_name, q->cra_driver_name) &&
+                    q->cra_priority > alg->cra_priority)
+                        continue;
+
+                crypto_remove_spawns(&q->cra_users, list);
         }
         
         list_add(&alg->cra_list, &crypto_alg_list);
@@ -105,8 +175,20 @@ out:
         return ret;
 }
 
+static void crypto_remove_final(struct list_head *list)
+{
+        struct crypto_alg *alg;
+        struct crypto_alg *n;
+
+        list_for_each_entry_safe(alg, n, list, cra_list) {
+                list_del_init(&alg->cra_list);
+                crypto_alg_put(alg);
+        }
+}
+
 int crypto_register_alg(struct crypto_alg *alg)
 {
+        LIST_HEAD(list);
         int err;
 
         err = crypto_check_alg(alg);
@@ -114,23 +196,35 @@ int crypto_register_alg(struct crypto_alg *alg)
                 return err;
 
         down_write(&crypto_alg_sem);
-        err = __crypto_register_alg(alg);
+        err = __crypto_register_alg(alg, &list);
         up_write(&crypto_alg_sem);
 
+        crypto_remove_final(&list);
         return err;
 }
 EXPORT_SYMBOL_GPL(crypto_register_alg);
 
+static int crypto_remove_alg(struct crypto_alg *alg, struct list_head *list)
+{
+        if (unlikely(list_empty(&alg->cra_list)))
+                return -ENOENT;
+
+        alg->cra_flags |= CRYPTO_ALG_DEAD;
+
+        crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, alg);
+        list_del_init(&alg->cra_list);
+        crypto_remove_spawns(&alg->cra_users, list);
+
+        return 0;
+}
+
 int crypto_unregister_alg(struct crypto_alg *alg)
 {
-        int ret = -ENOENT;
+        int ret;
+        LIST_HEAD(list);
         
         down_write(&crypto_alg_sem);
-        if (likely(!list_empty(&alg->cra_list))) {
-                list_del_init(&alg->cra_list);
-                ret = 0;
-        }
-        crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, alg);
+        ret = crypto_remove_alg(alg, &list);
         up_write(&crypto_alg_sem);
 
         if (ret)
@@ -140,6 +234,7 @@ int crypto_unregister_alg(struct crypto_alg *alg)
         if (alg->cra_destroy)
                 alg->cra_destroy(alg);
 
+        crypto_remove_final(&list);
         return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_alg);
@@ -170,6 +265,7 @@ void crypto_unregister_template(struct crypto_template *tmpl)
         struct crypto_instance *inst;
         struct hlist_node *p, *n;
         struct hlist_head *list;
+        LIST_HEAD(users);
 
         down_write(&crypto_alg_sem);
 
@@ -178,9 +274,8 @@ void crypto_unregister_template(struct crypto_template *tmpl)
 
         list = &tmpl->instances;
         hlist_for_each_entry(inst, p, list, list) {
-                BUG_ON(list_empty(&inst->alg.cra_list));
-                list_del_init(&inst->alg.cra_list);
-                crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, &inst->alg);
+                int err = crypto_remove_alg(&inst->alg, &users);
+                BUG_ON(err);
         }
 
         crypto_notify(CRYPTO_MSG_TMPL_UNREGISTER, tmpl);
@@ -191,6 +286,7 @@ void crypto_unregister_template(struct crypto_template *tmpl)
                 BUG_ON(atomic_read(&inst->alg.cra_refcnt) != 1);
                 tmpl->free(inst);
         }
+        crypto_remove_final(&users);
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_template);
 
@@ -222,6 +318,7 @@ EXPORT_SYMBOL_GPL(crypto_lookup_template);
 int crypto_register_instance(struct crypto_template *tmpl,
                              struct crypto_instance *inst)
 {
+        LIST_HEAD(list);
         int err = -EINVAL;
 
         if (inst->alg.cra_destroy)
@@ -235,7 +332,7 @@ int crypto_register_instance(struct crypto_template *tmpl,
 
         down_write(&crypto_alg_sem);
 
-        err = __crypto_register_alg(&inst->alg);
+        err = __crypto_register_alg(&inst->alg, &list);
         if (err)
                 goto unlock;
 
@@ -245,11 +342,67 @@ int crypto_register_instance(struct crypto_template *tmpl,
 unlock:
         up_write(&crypto_alg_sem);
 
+        crypto_remove_final(&list);
+
 err:
         return err;
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
 
+int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
+                      struct crypto_instance *inst)
+{
+        int err = -EAGAIN;
+
+        spawn->inst = inst;
+
+        down_write(&crypto_alg_sem);
+        if (!crypto_is_moribund(alg)) {
+                list_add(&spawn->list, &alg->cra_users);
+                spawn->alg = alg;
+                err = 0;
+        }
+        up_write(&crypto_alg_sem);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(crypto_init_spawn);
+
+void crypto_drop_spawn(struct crypto_spawn *spawn)
+{
+        down_write(&crypto_alg_sem);
+        list_del(&spawn->list);
+        up_write(&crypto_alg_sem);
+}
+EXPORT_SYMBOL_GPL(crypto_drop_spawn);
+
+struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn)
+{
+        struct crypto_alg *alg;
+        struct crypto_alg *alg2;
+        struct crypto_tfm *tfm;
+
+        down_read(&crypto_alg_sem);
+        alg = spawn->alg;
+        alg2 = alg;
+        if (alg2)
+                alg2 = crypto_mod_get(alg2);
+        up_read(&crypto_alg_sem);
+
+        if (!alg2) {
+                if (alg)
+                        crypto_shoot_alg(alg);
+                return ERR_PTR(-EAGAIN);
+        }
+
+        tfm = __crypto_alloc_tfm(alg, 0);
+        if (IS_ERR(tfm))
+                crypto_mod_put(alg);
+
+        return tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_spawn_tfm);
+
 int crypto_register_notifier(struct notifier_block *nb)
 {
         return blocking_notifier_chain_register(&crypto_chain, nb);