Revision 0620fddb56dfaf0e1034eeb69d79c73b361debbf authored by Eric Biggers on 08 June 2017, 13:49:26 UTC, committed by James Morris on 09 June 2017, 03:29:48 UTC
While a 'struct key' itself normally does not contain sensitive
information, Documentation/security/keys.txt actually encourages this:

     "Having a payload is not required; and the payload can, in fact,
     just be a value stored in the struct key itself."

In case someone has taken this advice, or will take this advice in the
future, zero the key structure before freeing it.  We might as well, and
as a bonus this could make it a bit more difficult for an adversary to
determine which keys have recently been in use.

This is safe because the key_jar cache does not use a constructor.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
1 parent ee618b4
Raw File
akcipher.c
/*
 * Public Key Encryption
 *
 * Copyright (c) 2015, Intel Corporation
 * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/compiler.h>
#include <crypto/algapi.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <crypto/akcipher.h>
#include <crypto/internal/akcipher.h>
#include "internal.h"

#ifdef CONFIG_NET
static int crypto_akcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
	struct crypto_report_akcipher rakcipher;

	strncpy(rakcipher.type, "akcipher", sizeof(rakcipher.type));

	if (nla_put(skb, CRYPTOCFGA_REPORT_AKCIPHER,
		    sizeof(struct crypto_report_akcipher), &rakcipher))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -EMSGSIZE;
}
#else
static int crypto_akcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
	return -ENOSYS;
}
#endif

static void crypto_akcipher_show(struct seq_file *m, struct crypto_alg *alg)
	__maybe_unused;

static void crypto_akcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
	seq_puts(m, "type         : akcipher\n");
}

static void crypto_akcipher_exit_tfm(struct crypto_tfm *tfm)
{
	struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
	struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);

	alg->exit(akcipher);
}

static int crypto_akcipher_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
	struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);

	if (alg->exit)
		akcipher->base.exit = crypto_akcipher_exit_tfm;

	if (alg->init)
		return alg->init(akcipher);

	return 0;
}

static void crypto_akcipher_free_instance(struct crypto_instance *inst)
{
	struct akcipher_instance *akcipher = akcipher_instance(inst);

	akcipher->free(akcipher);
}

static const struct crypto_type crypto_akcipher_type = {
	.extsize = crypto_alg_extsize,
	.init_tfm = crypto_akcipher_init_tfm,
	.free = crypto_akcipher_free_instance,
#ifdef CONFIG_PROC_FS
	.show = crypto_akcipher_show,
#endif
	.report = crypto_akcipher_report,
	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
	.maskset = CRYPTO_ALG_TYPE_MASK,
	.type = CRYPTO_ALG_TYPE_AKCIPHER,
	.tfmsize = offsetof(struct crypto_akcipher, base),
};

int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn, const char *name,
			 u32 type, u32 mask)
{
	spawn->base.frontend = &crypto_akcipher_type;
	return crypto_grab_spawn(&spawn->base, name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_grab_akcipher);

struct crypto_akcipher *crypto_alloc_akcipher(const char *alg_name, u32 type,
					      u32 mask)
{
	return crypto_alloc_tfm(alg_name, &crypto_akcipher_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_akcipher);

static void akcipher_prepare_alg(struct akcipher_alg *alg)
{
	struct crypto_alg *base = &alg->base;

	base->cra_type = &crypto_akcipher_type;
	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
	base->cra_flags |= CRYPTO_ALG_TYPE_AKCIPHER;
}

int crypto_register_akcipher(struct akcipher_alg *alg)
{
	struct crypto_alg *base = &alg->base;

	akcipher_prepare_alg(alg);
	return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_akcipher);

void crypto_unregister_akcipher(struct akcipher_alg *alg)
{
	crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_akcipher);

int akcipher_register_instance(struct crypto_template *tmpl,
			       struct akcipher_instance *inst)
{
	akcipher_prepare_alg(&inst->alg);
	return crypto_register_instance(tmpl, akcipher_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(akcipher_register_instance);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic public key cipher type");
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