[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>

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 @@ static int __crypto_register_alg(struct crypto_alg *alg)
 	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);

crypto/api.c

@@ -15,11 +15,13 @@
  *
  */
 
+#include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/kmod.h>
 #include <linux/module.h>
 #include <linux/param.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include "internal.h"
@@ -38,12 +40,6 @@ static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
 	return alg;
 }
 
-static inline void crypto_alg_put(struct crypto_alg *alg)
-{
-	if (atomic_dec_and_test(&alg->cra_refcnt) && alg->cra_destroy)
-		alg->cra_destroy(alg);
-}
-
 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
 {
 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
@@ -65,6 +61,9 @@ struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type, u32 mask)
 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
 		int exact, fuzzy;
 
+		if (crypto_is_moribund(q))
+			continue;
+
 		if ((q->cra_flags ^ type) & mask)
 			continue;
 
@@ -111,7 +110,7 @@ static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
 
 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
 	if (!larval)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	larval->mask = mask;
 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
@@ -153,8 +152,11 @@ static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
 
 	wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
 	alg = larval->adult;
-	if (alg && !crypto_mod_get(alg))
-		alg = NULL;
+	if (alg) {
+		if (!crypto_mod_get(alg))
+			alg = ERR_PTR(-EAGAIN);
+	} else
+		alg = ERR_PTR(-ENOENT);
 	crypto_mod_put(&larval->alg);
 
 	return alg;
@@ -165,9 +167,6 @@ static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
 {
 	struct crypto_alg *alg;
 
-	if (!name)
-		return NULL;
-
 	down_read(&crypto_alg_sem);
 	alg = __crypto_alg_lookup(name, type, mask);
 	up_read(&crypto_alg_sem);
@@ -181,7 +180,10 @@ struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 	struct crypto_alg *larval;
 	int ok;
 
-	mask &= ~CRYPTO_ALG_LARVAL;
+	if (!name)
+		return ERR_PTR(-ENOENT);
+
+	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
 	type &= mask;
 
 	alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
@@ -190,7 +192,7 @@ struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 
 	larval = crypto_larval_alloc(name, type, mask);
-	if (!larval || !crypto_is_larval(larval))
+	if (IS_ERR(larval) || !crypto_is_larval(larval))
 		return larval;
 
 	ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
@@ -203,7 +205,7 @@ struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
 		alg = crypto_larval_wait(larval);
 	else {
 		crypto_mod_put(larval);
-		alg = NULL;
+		alg = ERR_PTR(-ENOENT);
 	}
 	crypto_larval_kill(larval);
 	return alg;
@@ -298,31 +300,40 @@ static unsigned int crypto_ctxsize(struct crypto_alg *alg, int flags)
 	return len + (alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 }
 
-struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
+void crypto_shoot_alg(struct crypto_alg *alg)
+{
+	down_write(&crypto_alg_sem);
+	alg->cra_flags |= CRYPTO_ALG_DYING;
+	up_write(&crypto_alg_sem);
+}
+EXPORT_SYMBOL_GPL(crypto_shoot_alg);
+
+struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 flags)
 {
 	struct crypto_tfm *tfm = NULL;
-	struct crypto_alg *alg;
 	unsigned int tfm_size;
-
-	alg = crypto_alg_mod_lookup(name, 0, 0);
-	if (alg == NULL)
-		goto out;
+	int err = -ENOMEM;
 
 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, flags);
 	tfm = kzalloc(tfm_size, GFP_KERNEL);
 	if (tfm == NULL)
-		goto out_put;
+		goto out;
 
 	tfm->__crt_alg = alg;
-	
-	if (crypto_init_flags(tfm, flags))
+
+	err = crypto_init_flags(tfm, flags);
+	if (err)
 		goto out_free_tfm;
 		
-	if (crypto_init_ops(tfm))
+	err = crypto_init_ops(tfm);
+	if (err)
 		goto out_free_tfm;
 
-	if (alg->cra_init && alg->cra_init(tfm))
+	if (alg->cra_init && (err = alg->cra_init(tfm))) {
+		if (err == -EAGAIN)
+			crypto_shoot_alg(alg);
 		goto cra_init_failed;
+	}
 
 	goto out;
 
@@ -330,12 +341,36 @@ struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
 	crypto_exit_ops(tfm);
 out_free_tfm:
 	kfree(tfm);
-	tfm = NULL;
-out_put:
-	crypto_mod_put(alg);
+	tfm = ERR_PTR(err);
 out:
 	return tfm;
 }
+EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
+
+struct crypto_tfm *crypto_alloc_tfm(const char *name, u32 flags)
+{
+	struct crypto_tfm *tfm = NULL;
+	int err;
+
+	do {
+		struct crypto_alg *alg;
+
+		alg = crypto_alg_mod_lookup(name, 0, 0);
+		err = PTR_ERR(alg);
+		if (IS_ERR(alg))
+			continue;
+
+		tfm = __crypto_alloc_tfm(alg, flags);
+		err = 0;
+		if (IS_ERR(tfm)) {
+			crypto_mod_put(alg);
+			err = PTR_ERR(tfm);
+			tfm = NULL;
+		}
+	} while (err == -EAGAIN && !signal_pending(current));
+
+	return tfm;
+}
 
 void crypto_free_tfm(struct crypto_tfm *tfm)
 {
@@ -361,7 +396,7 @@ int crypto_alg_available(const char *name, u32 flags)
 	int ret = 0;
 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, 0, 0);
 	
-	if (alg) {
+	if (!IS_ERR(alg)) {
 		crypto_mod_put(alg);
 		ret = 1;
 	}

crypto/cryptomgr.c

@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/rtnetlink.h>
+#include <linux/sched.h>
 #include <linux/string.h>
 #include <linux/workqueue.h>
 
@@ -44,21 +45,25 @@ static void cryptomgr_probe(void *data)
 	struct cryptomgr_param *param = data;
 	struct crypto_template *tmpl;
 	struct crypto_instance *inst;
+	int err;
 
 	tmpl = crypto_lookup_template(param->template);
 	if (!tmpl)
 		goto err;
 
-	inst = tmpl->alloc(&param->alg, sizeof(param->alg));
-	if (IS_ERR(inst))
-		goto err;
-	else if ((err = crypto_register_instance(tmpl, inst))) {
-		tmpl->free(inst);
-		goto err;
-	}
+	do {
+		inst = tmpl->alloc(&param->alg, sizeof(param->alg));
+		if (IS_ERR(inst))
+			err = PTR_ERR(inst);
+		else if ((err = crypto_register_instance(tmpl, inst)))
+			tmpl->free(inst);
+	} while (err == -EAGAIN && !signal_pending(current));
 
 	crypto_tmpl_put(tmpl);
 
+	if (err)
+		goto err;
+
 out:
 	kfree(param);
 	return;

crypto/internal.h

@@ -142,12 +142,21 @@ void crypto_exit_compress_ops(struct crypto_tfm *tfm);
 
 void crypto_larval_error(const char *name, u32 type, u32 mask);
 
+void crypto_shoot_alg(struct crypto_alg *alg);
+struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 flags);
+
 int crypto_register_instance(struct crypto_template *tmpl,
 			     struct crypto_instance *inst);
 
 int crypto_register_notifier(struct notifier_block *nb);
 int crypto_unregister_notifier(struct notifier_block *nb);
 
+static inline void crypto_alg_put(struct crypto_alg *alg)
+{
+	if (atomic_dec_and_test(&alg->cra_refcnt) && alg->cra_destroy)
+		alg->cra_destroy(alg);
+}
+
 static inline int crypto_tmpl_get(struct crypto_template *tmpl)
 {
 	return try_module_get(tmpl->module);
@@ -163,6 +172,16 @@ static inline int crypto_is_larval(struct crypto_alg *alg)
 	return alg->cra_flags & CRYPTO_ALG_LARVAL;
 }
 
+static inline int crypto_is_dead(struct crypto_alg *alg)
+{
+	return alg->cra_flags & CRYPTO_ALG_DEAD;
+}
+
+static inline int crypto_is_moribund(struct crypto_alg *alg)
+{
+	return alg->cra_flags & (CRYPTO_ALG_DEAD | CRYPTO_ALG_DYING);
+}
+
 static inline int crypto_notify(unsigned long val, void *v)
 {
 	return blocking_notifier_call_chain(&crypto_chain, val, v);

include/crypto/algapi.h

@@ -36,10 +36,21 @@ struct crypto_template {
 	char name[CRYPTO_MAX_ALG_NAME];
 };
 
+struct crypto_spawn {
+	struct list_head list;
+	struct crypto_alg *alg;
+	struct crypto_instance *inst;
+};
+
 int crypto_register_template(struct crypto_template *tmpl);
 void crypto_unregister_template(struct crypto_template *tmpl);
 struct crypto_template *crypto_lookup_template(const char *name);
 
+int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
+		      struct crypto_instance *inst);
+void crypto_drop_spawn(struct crypto_spawn *spawn);
+struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn);
+
 static inline void *crypto_instance_ctx(struct crypto_instance *inst)
 {
 	return inst->__ctx;

include/linux/crypto.h

@@ -35,6 +35,8 @@
 #define CRYPTO_ALG_TYPE_COMPRESS	0x00000004
 
 #define CRYPTO_ALG_LARVAL		0x00000010
+#define CRYPTO_ALG_DEAD			0x00000020
+#define CRYPTO_ALG_DYING		0x00000040
 
 /*
  * Transform masks and values (for crt_flags).
@@ -145,6 +147,8 @@ struct compress_alg {
 
 struct crypto_alg {
 	struct list_head cra_list;
+	struct list_head cra_users;
+
 	u32 cra_flags;
 	unsigned int cra_blocksize;
 	unsigned int cra_ctxsize;