linux/crypto/ecdh.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/* ECDH key-agreement protocol
*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
*/
#include <linux/module.h>
#include <crypto/internal/ecc.h>
#include <crypto/internal/kpp.h>
#include <crypto/kpp.h>
#include <crypto/ecdh.h>
#include <linux/scatterlist.h>
struct ecdh_ctx {
unsigned int curve_id;
unsigned int ndigits;
u64 private_key[ECC_MAX_DIGITS];
};
static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
{
return kpp_tfm_ctx(tfm);
}
static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
unsigned int len)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
struct ecdh params;
if (crypto_ecdh_decode_key(buf, len, &params) < 0 ||
params.key_size > sizeof(u64) * ctx->ndigits)
return -EINVAL;
if (!params.key || !params.key_size)
return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
ctx->private_key);
memcpy(ctx->private_key, params.key, params.key_size);
if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
ctx->private_key, params.key_size) < 0) {
memzero_explicit(ctx->private_key, params.key_size);
return -EINVAL;
}
return 0;
}
static int ecdh_compute_value(struct kpp_request *req)
{
struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
u64 *public_key;
u64 *shared_secret = NULL;
void *buf;
size_t copied, nbytes, public_key_sz;
int ret = -ENOMEM;
nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
/* Public part is a point thus it has both coordinates */
public_key_sz = 2 * nbytes;
public_key = kmalloc(public_key_sz, GFP_KERNEL);
if (!public_key)
return -ENOMEM;
if (req->src) {
shared_secret = kmalloc(nbytes, GFP_KERNEL);
if (!shared_secret)
goto free_pubkey;
/* from here on it's invalid parameters */
ret = -EINVAL;
/* must have exactly two points to be on the curve */
if (public_key_sz != req->src_len)
goto free_all;
copied = sg_copy_to_buffer(req->src,
sg_nents_for_len(req->src,
public_key_sz),
public_key, public_key_sz);
if (copied != public_key_sz)
goto free_all;
ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
ctx->private_key, public_key,
shared_secret);
buf = shared_secret;
} else {
ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
ctx->private_key, public_key);
buf = public_key;
nbytes = public_key_sz;
}
if (ret < 0)
goto free_all;
/* might want less than we've got */
nbytes = min_t(size_t, nbytes, req->dst_len);
copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
nbytes),
buf, nbytes);
if (copied != nbytes)
ret = -EINVAL;
/* fall through */
free_all:
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 06:18:13 +00:00
kfree_sensitive(shared_secret);
free_pubkey:
kfree(public_key);
return ret;
}
static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
/* Public key is made of two coordinates, add one to the left shift */
return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
}
static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
ctx->curve_id = ECC_CURVE_NIST_P192;
ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS;
return 0;
}
static struct kpp_alg ecdh_nist_p192 = {
.set_secret = ecdh_set_secret,
.generate_public_key = ecdh_compute_value,
.compute_shared_secret = ecdh_compute_value,
.max_size = ecdh_max_size,
.init = ecdh_nist_p192_init_tfm,
.base = {
.cra_name = "ecdh-nist-p192",
.cra_driver_name = "ecdh-nist-p192-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecdh_ctx),
},
};
static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
ctx->curve_id = ECC_CURVE_NIST_P256;
ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS;
return 0;
}
static struct kpp_alg ecdh_nist_p256 = {
.set_secret = ecdh_set_secret,
.generate_public_key = ecdh_compute_value,
.compute_shared_secret = ecdh_compute_value,
.max_size = ecdh_max_size,
.init = ecdh_nist_p256_init_tfm,
.base = {
.cra_name = "ecdh-nist-p256",
.cra_driver_name = "ecdh-nist-p256-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecdh_ctx),
},
};
static int ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm)
{
struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
ctx->curve_id = ECC_CURVE_NIST_P384;
ctx->ndigits = ECC_CURVE_NIST_P384_DIGITS;
return 0;
}
static struct kpp_alg ecdh_nist_p384 = {
.set_secret = ecdh_set_secret,
.generate_public_key = ecdh_compute_value,
.compute_shared_secret = ecdh_compute_value,
.max_size = ecdh_max_size,
.init = ecdh_nist_p384_init_tfm,
.base = {
.cra_name = "ecdh-nist-p384",
.cra_driver_name = "ecdh-nist-p384-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecdh_ctx),
},
};
static bool ecdh_nist_p192_registered;
static int ecdh_init(void)
{
int ret;
/* NIST p192 will fail to register in FIPS mode */
ret = crypto_register_kpp(&ecdh_nist_p192);
ecdh_nist_p192_registered = ret == 0;
ret = crypto_register_kpp(&ecdh_nist_p256);
if (ret)
goto nist_p256_error;
ret = crypto_register_kpp(&ecdh_nist_p384);
if (ret)
goto nist_p384_error;
return 0;
nist_p384_error:
crypto_unregister_kpp(&ecdh_nist_p256);
nist_p256_error:
if (ecdh_nist_p192_registered)
crypto_unregister_kpp(&ecdh_nist_p192);
return ret;
}
static void ecdh_exit(void)
{
if (ecdh_nist_p192_registered)
crypto_unregister_kpp(&ecdh_nist_p192);
crypto_unregister_kpp(&ecdh_nist_p256);
crypto_unregister_kpp(&ecdh_nist_p384);
}
subsys_initcall(ecdh_init);
module_exit(ecdh_exit);
MODULE_ALIAS_CRYPTO("ecdh");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ECDH generic algorithm");