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linux-next/crypto/rng.c
Waiman Long 453431a549 mm, treewide: rename kzfree() to kfree_sensitive()
As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-07 11:33:22 -07:00

233 lines
4.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Cryptographic API.
*
* RNG operations.
*
* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
*/
#include <linux/atomic.h>
#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/cryptouser.h>
#include <linux/compiler.h>
#include <net/netlink.h>
#include "internal.h"
static DEFINE_MUTEX(crypto_default_rng_lock);
struct crypto_rng *crypto_default_rng;
EXPORT_SYMBOL_GPL(crypto_default_rng);
static int crypto_default_rng_refcnt;
int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
{
struct crypto_alg *alg = tfm->base.__crt_alg;
u8 *buf = NULL;
int err;
crypto_stats_get(alg);
if (!seed && slen) {
buf = kmalloc(slen, GFP_KERNEL);
if (!buf) {
crypto_alg_put(alg);
return -ENOMEM;
}
err = get_random_bytes_wait(buf, slen);
if (err) {
crypto_alg_put(alg);
goto out;
}
seed = buf;
}
err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
crypto_stats_rng_seed(alg, err);
out:
kfree_sensitive(buf);
return err;
}
EXPORT_SYMBOL_GPL(crypto_rng_reset);
static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
{
return 0;
}
static unsigned int seedsize(struct crypto_alg *alg)
{
struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
return ralg->seedsize;
}
#ifdef CONFIG_NET
static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_rng rrng;
memset(&rrng, 0, sizeof(rrng));
strscpy(rrng.type, "rng", sizeof(rrng.type));
rrng.seedsize = seedsize(alg);
return nla_put(skb, CRYPTOCFGA_REPORT_RNG, sizeof(rrng), &rrng);
}
#else
static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_printf(m, "type : rng\n");
seq_printf(m, "seedsize : %u\n", seedsize(alg));
}
static const struct crypto_type crypto_rng_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_rng_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_rng_show,
#endif
.report = crypto_rng_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_RNG,
.tfmsize = offsetof(struct crypto_rng, base),
};
struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
{
return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_rng);
int crypto_get_default_rng(void)
{
struct crypto_rng *rng;
int err;
mutex_lock(&crypto_default_rng_lock);
if (!crypto_default_rng) {
rng = crypto_alloc_rng("stdrng", 0, 0);
err = PTR_ERR(rng);
if (IS_ERR(rng))
goto unlock;
err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
if (err) {
crypto_free_rng(rng);
goto unlock;
}
crypto_default_rng = rng;
}
crypto_default_rng_refcnt++;
err = 0;
unlock:
mutex_unlock(&crypto_default_rng_lock);
return err;
}
EXPORT_SYMBOL_GPL(crypto_get_default_rng);
void crypto_put_default_rng(void)
{
mutex_lock(&crypto_default_rng_lock);
crypto_default_rng_refcnt--;
mutex_unlock(&crypto_default_rng_lock);
}
EXPORT_SYMBOL_GPL(crypto_put_default_rng);
#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
int crypto_del_default_rng(void)
{
int err = -EBUSY;
mutex_lock(&crypto_default_rng_lock);
if (crypto_default_rng_refcnt)
goto out;
crypto_free_rng(crypto_default_rng);
crypto_default_rng = NULL;
err = 0;
out:
mutex_unlock(&crypto_default_rng_lock);
return err;
}
EXPORT_SYMBOL_GPL(crypto_del_default_rng);
#endif
int crypto_register_rng(struct rng_alg *alg)
{
struct crypto_alg *base = &alg->base;
if (alg->seedsize > PAGE_SIZE / 8)
return -EINVAL;
base->cra_type = &crypto_rng_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_rng);
void crypto_unregister_rng(struct rng_alg *alg)
{
crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_rng);
int crypto_register_rngs(struct rng_alg *algs, int count)
{
int i, ret;
for (i = 0; i < count; i++) {
ret = crypto_register_rng(algs + i);
if (ret)
goto err;
}
return 0;
err:
for (--i; i >= 0; --i)
crypto_unregister_rng(algs + i);
return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_rngs);
void crypto_unregister_rngs(struct rng_alg *algs, int count)
{
int i;
for (i = count - 1; i >= 0; --i)
crypto_unregister_rng(algs + i);
}
EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Random Number Generator");