[CRYPTO] api: Added event notification

This patch adds a notifier chain for algorithm/template registration events.
This will be used to register compound algorithms such as cbc(aes).  In
future this will also be passed onto user-space through netlink.

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

3 files changed, 196 insertions, 13 deletions

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 232b37d816..f0df85fc1f 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -21,6 +21,24 @@
 
 static LIST_HEAD(crypto_template_list);
 
+void crypto_larval_error(const char *name)
+{
+        struct crypto_alg *alg;
+
+        down_read(&crypto_alg_sem);
+        alg = __crypto_alg_lookup(name);
+        up_read(&crypto_alg_sem);
+
+        if (alg) {
+                if (crypto_is_larval(alg)) {
+                        struct crypto_larval *larval = (void *)alg;
+                        complete(&larval->completion);
+                }
+                crypto_mod_put(alg);
+        }
+}
+EXPORT_SYMBOL_GPL(crypto_larval_error);
+
 static inline int crypto_set_driver_name(struct crypto_alg *alg)
 {
         static const char suffix[] = "-generic";
@@ -60,14 +78,27 @@ static int __crypto_register_alg(struct crypto_alg *alg)
         struct crypto_alg *q;
         int 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))) {
+                        struct crypto_larval *larval = (void *)q;
+
+                        if (!crypto_mod_get(alg))
+                                continue;
+                        larval->adult = alg;
+                        complete(&larval->completion);
+                }
         }
         
         list_add(&alg->cra_list, &crypto_alg_list);
-        atomic_set(&alg->cra_refcnt, 1);
+
+        crypto_notify(CRYPTO_MSG_ALG_REGISTER, alg);
         ret = 0;
+
 out:    
         return ret;
 }
@@ -97,6 +128,7 @@ int crypto_unregister_alg(struct crypto_alg *alg)
                 list_del_init(&alg->cra_list);
                 ret = 0;
         }
+        crypto_notify(CRYPTO_MSG_ALG_UNREGISTER, alg);
         up_write(&crypto_alg_sem);
 
         if (ret)
@@ -123,6 +155,7 @@ int crypto_register_template(struct crypto_template *tmpl)
         }
 
         list_add(&tmpl->list, &crypto_template_list);
+        crypto_notify(CRYPTO_MSG_TMPL_REGISTER, tmpl);
         err = 0;
 out:
         up_write(&crypto_alg_sem);
@@ -145,8 +178,11 @@ void crypto_unregister_template(struct crypto_template *tmpl)
         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);
         }
 
+        crypto_notify(CRYPTO_MSG_TMPL_UNREGISTER, tmpl);
+
         up_write(&crypto_alg_sem);
 
         hlist_for_each_entry_safe(inst, p, n, list, list) {
@@ -212,6 +248,18 @@ err:
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
 
+int crypto_register_notifier(struct notifier_block *nb)
+{
+        return blocking_notifier_chain_register(&crypto_chain, nb);
+}
+EXPORT_SYMBOL_GPL(crypto_register_notifier);
+
+int crypto_unregister_notifier(struct notifier_block *nb)
+{
+        return blocking_notifier_chain_unregister(&crypto_chain, nb);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_notifier);
+
 static int __init crypto_algapi_init(void)
 {
         crypto_init_proc();
diff --git a/crypto/api.c b/crypto/api.c
index c922090b48..5a0d6a17cf 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -18,6 +18,7 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/kmod.h>
+#include <linux/param.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include "internal.h"
@@ -27,6 +28,9 @@ EXPORT_SYMBOL_GPL(crypto_alg_list);
 DECLARE_RWSEM(crypto_alg_sem);
 EXPORT_SYMBOL_GPL(crypto_alg_sem);
 
+BLOCKING_NOTIFIER_HEAD(crypto_chain);
+EXPORT_SYMBOL_GPL(crypto_chain);
+
 static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
 {
         atomic_inc(&alg->cra_refcnt);
@@ -39,27 +43,24 @@ static inline void crypto_alg_put(struct crypto_alg *alg)
                 alg->cra_destroy(alg);
 }
 
-static struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
+struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
 {
         return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
 }
+EXPORT_SYMBOL_GPL(crypto_mod_get);
 
-static void crypto_mod_put(struct crypto_alg *alg)
+void crypto_mod_put(struct crypto_alg *alg)
 {
         crypto_alg_put(alg);
         module_put(alg->cra_module);
 }
+EXPORT_SYMBOL_GPL(crypto_mod_put);
 
-static struct crypto_alg *crypto_alg_lookup(const char *name)
+struct crypto_alg *__crypto_alg_lookup(const char *name)
 {
         struct crypto_alg *q, *alg = NULL;
-        int best = -1;
+        int best = -2;
 
-        if (!name)
-                return NULL;
-        
-        down_read(&crypto_alg_sem);
-        
         list_for_each_entry(q, &crypto_alg_list, cra_list) {
                 int exact, fuzzy;
 
@@ -79,16 +80,113 @@ static struct crypto_alg *crypto_alg_lookup(const char *name)
                 if (exact)
                         break;
         }
-        
+
+        return alg;
+}
+EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
+
+static void crypto_larval_destroy(struct crypto_alg *alg)
+{
+        struct crypto_larval *larval = (void *)alg;
+
+        BUG_ON(!crypto_is_larval(alg));
+        if (larval->adult)
+                crypto_mod_put(larval->adult);
+        kfree(larval);
+}
+
+static struct crypto_alg *crypto_larval_alloc(const char *name)
+{
+        struct crypto_alg *alg;
+        struct crypto_larval *larval;
+
+        larval = kzalloc(sizeof(*larval), GFP_KERNEL);
+        if (!larval)
+                return NULL;
+
+        larval->alg.cra_flags = CRYPTO_ALG_LARVAL;
+        larval->alg.cra_priority = -1;
+        larval->alg.cra_destroy = crypto_larval_destroy;
+
+        atomic_set(&larval->alg.cra_refcnt, 2);
+        strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
+        init_completion(&larval->completion);
+
+        down_write(&crypto_alg_sem);
+        alg = __crypto_alg_lookup(name);
+        if (!alg) {
+                alg = &larval->alg;
+                list_add(&alg->cra_list, &crypto_alg_list);
+        }
+        up_write(&crypto_alg_sem);
+
+        if (alg != &larval->alg)
+                kfree(larval);
+
+        return alg;
+}
+
+static void crypto_larval_kill(struct crypto_alg *alg)
+{
+        struct crypto_larval *larval = (void *)alg;
+
+        down_write(&crypto_alg_sem);
+        list_del(&alg->cra_list);
+        up_write(&crypto_alg_sem);
+        complete(&larval->completion);
+        crypto_alg_put(alg);
+}
+
+static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
+{
+        struct crypto_larval *larval = (void *)alg;
+
+        wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
+        alg = larval->adult;
+        if (alg && !crypto_mod_get(alg))
+                alg = NULL;
+        crypto_mod_put(&larval->alg);
+
+        return alg;
+}
+
+static struct crypto_alg *crypto_alg_lookup(const char *name)
+{
+        struct crypto_alg *alg;
+
+        if (!name)
+                return NULL;
+
+        down_read(&crypto_alg_sem);
+        alg = __crypto_alg_lookup(name);
         up_read(&crypto_alg_sem);
+
         return alg;
 }
 
 /* A far more intelligent version of this is planned.  For now, just
  * try an exact match on the name of the algorithm. */
-static inline struct crypto_alg *crypto_alg_mod_lookup(const char *name)
+static struct crypto_alg *crypto_alg_mod_lookup(const char *name)
 {
-        return try_then_request_module(crypto_alg_lookup(name), name);
+        struct crypto_alg *alg;
+        struct crypto_alg *larval;
+
+        alg = try_then_request_module(crypto_alg_lookup(name), name);
+        if (alg)
+                return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
+
+        larval = crypto_larval_alloc(name);
+        if (!larval || !crypto_is_larval(larval))
+                return larval;
+
+        if (crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval) == NOTIFY_STOP)
+                alg = crypto_larval_wait(larval);
+        else {
+                crypto_mod_put(larval);
+                alg = NULL;
+        }
+        crypto_larval_kill(larval);
+        return alg;
 }
 
 static int crypto_init_flags(struct crypto_tfm *tfm, u32 flags)
diff --git a/crypto/internal.h b/crypto/internal.h
index c3ab4a950f..3a08d25fba 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -14,6 +14,7 @@
 #define _CRYPTO_INTERNAL_H
 
 #include <crypto/algapi.h>
+#include <linux/completion.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/interrupt.h>
@@ -21,15 +22,32 @@
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/notifier.h>
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <asm/kmap_types.h>
 
+/* Crypto notification events. */
+enum {
+        CRYPTO_MSG_ALG_REQUEST,
+        CRYPTO_MSG_ALG_REGISTER,
+        CRYPTO_MSG_ALG_UNREGISTER,
+        CRYPTO_MSG_TMPL_REGISTER,
+        CRYPTO_MSG_TMPL_UNREGISTER,
+};
+
 struct crypto_instance;
 struct crypto_template;
 
+struct crypto_larval {
+        struct crypto_alg alg;
+        struct crypto_alg *adult;
+        struct completion completion;
+};
+
 extern struct list_head crypto_alg_list;
 extern struct rw_semaphore crypto_alg_sem;
+extern struct blocking_notifier_head crypto_chain;
 
 extern enum km_type crypto_km_types[];
 
@@ -104,6 +122,10 @@ static inline unsigned int crypto_compress_ctxsize(struct crypto_alg *alg,
         return alg->cra_ctxsize;
 }
 
+struct crypto_alg *crypto_mod_get(struct crypto_alg *alg);
+void crypto_mod_put(struct crypto_alg *alg);
+struct crypto_alg *__crypto_alg_lookup(const char *name);
+
 int crypto_init_digest_flags(struct crypto_tfm *tfm, u32 flags);
 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags);
 int crypto_init_compress_flags(struct crypto_tfm *tfm, u32 flags);
@@ -116,9 +138,14 @@ 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_error(const char *name);
+
 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 int crypto_tmpl_get(struct crypto_template *tmpl)
 {
         return try_module_get(tmpl->module);
@@ -129,5 +156,15 @@ static inline void crypto_tmpl_put(struct crypto_template *tmpl)
         module_put(tmpl->module);
 }
 
+static inline int crypto_is_larval(struct crypto_alg *alg)
+{
+        return alg->cra_flags & CRYPTO_ALG_LARVAL;
+}
+
+static inline int crypto_notify(unsigned long val, void *v)
+{
+        return blocking_notifier_call_chain(&crypto_chain, val, v);
+}
+
 #endif  /* _CRYPTO_INTERNAL_H */