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Commit 6521f302 authored by Herbert Xu's avatar Herbert Xu
Browse files

[CRYPTO] api: Add crypto_alg reference counting 



Up until now we've relied on module reference counting to ensure that the
crypto_alg structures don't disappear from under us.  This was good enough
as long as each crypto_alg came from exactly one module.

However, with parameterised crypto algorithms a crypto_alg object may need
two or more modules to operate.  This means that we need to count the
references to the crypto_alg object directly.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 72fa4919

crypto/api.c

+26 −6
Original line number Diff line number Diff line
@@ -29,13 +29,26 @@ 
LIST_HEAD(crypto_alg_list);

DECLARE_RWSEM(crypto_alg_sem);



static inline int crypto_mod_get(struct crypto_alg *alg)

static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)

{

	return try_module_get(alg->cra_module);

	atomic_inc(&alg->cra_refcnt);

	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);

}



static struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)

{

	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;

}



static inline void crypto_mod_put(struct crypto_alg *alg)

static void crypto_mod_put(struct crypto_alg *alg)

{

	crypto_alg_put(alg);

	module_put(alg->cra_module);

}
@@ -274,6 +287,7 @@ int crypto_register_alg(struct crypto_alg *alg) 
	}

	

	list_add(&alg->cra_list, &crypto_alg_list);

	atomic_set(&alg->cra_refcnt, 1);

out:	

	up_write(&crypto_alg_sem);

	return ret;
@@ -284,8 +298,6 @@ int crypto_unregister_alg(struct crypto_alg *alg) 
	int ret = -ENOENT;

	struct crypto_alg *q;

	

	BUG_ON(!alg->cra_module);

	

	down_write(&crypto_alg_sem);

	list_for_each_entry(q, &crypto_alg_list, cra_list) {

		if (alg == q) {
@@ -296,7 +308,15 @@ int crypto_unregister_alg(struct crypto_alg *alg) 
	}

out:	

	up_write(&crypto_alg_sem);



	if (ret)

		return ret;



	BUG_ON(atomic_read(&alg->cra_refcnt) != 1);

	if (alg->cra_destroy)

		alg->cra_destroy(alg);



	return 0;

}



int crypto_alg_available(const char *name, u32 flags)

crypto/proc.c

+3 −0
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
 * any later version.

 *

 */



#include <asm/atomic.h>

#include <linux/init.h>

#include <linux/crypto.h>

#include <linux/rwsem.h>
@@ -54,6 +56,7 @@ static int c_show(struct seq_file *m, void *p) 
	seq_printf(m, "driver       : %s\n", alg->cra_driver_name);

	seq_printf(m, "module       : %s\n", module_name(alg->cra_module));

	seq_printf(m, "priority     : %d\n", alg->cra_priority);

	seq_printf(m, "refcnt       : %d\n", atomic_read(&alg->cra_refcnt));

	

	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {

	case CRYPTO_ALG_TYPE_CIPHER:

include/linux/crypto.h

+3 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#ifndef _LINUX_CRYPTO_H

#define _LINUX_CRYPTO_H



#include <asm/atomic.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/types.h>
@@ -148,6 +149,7 @@ struct crypto_alg { 
	unsigned int cra_alignmask;



	int cra_priority;

	atomic_t cra_refcnt;



	char cra_name[CRYPTO_MAX_ALG_NAME];

	char cra_driver_name[CRYPTO_MAX_ALG_NAME];
@@ -160,6 +162,7 @@ struct crypto_alg { 


	int (*cra_init)(struct crypto_tfm *tfm);

	void (*cra_exit)(struct crypto_tfm *tfm);

	void (*cra_destroy)(struct crypto_alg *alg);

	

	struct module *cra_module;

};