![Eric Biggers](/assets/img/avatar_default.png)
The X.509 parser mishandles the case where the certificate's signature's
hash algorithm is not available in the crypto API. In this case,
x509_get_sig_params() doesn't allocate the cert->sig->digest buffer;
this part seems to be intentional. However,
public_key_verify_signature() is still called via
x509_check_for_self_signed(), which triggers the 'BUG_ON(!sig->digest)'.
Fix this by making public_key_verify_signature() return -ENOPKG if the
hash buffer has not been allocated.
Reproducer when all the CONFIG_CRYPTO_SHA512* options are disabled:
openssl req -new -sha512 -x509 -batch -nodes -outform der \
| keyctl padd asymmetric desc @s
Fixes: 6c2dc5ae4a
("X.509: Extract signature digest and make self-signed cert checks earlier")
Reported-by: Paolo Valente <paolo.valente@linaro.org>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
173 lines
4.4 KiB
C
173 lines
4.4 KiB
C
/* In-software asymmetric public-key crypto subtype
|
|
*
|
|
* See Documentation/crypto/asymmetric-keys.txt
|
|
*
|
|
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public Licence
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the Licence, or (at your option) any later version.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "PKEY: "fmt
|
|
#include <linux/module.h>
|
|
#include <linux/export.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/scatterlist.h>
|
|
#include <keys/asymmetric-subtype.h>
|
|
#include <crypto/public_key.h>
|
|
#include <crypto/akcipher.h>
|
|
|
|
MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
|
|
MODULE_AUTHOR("Red Hat, Inc.");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
/*
|
|
* Provide a part of a description of the key for /proc/keys.
|
|
*/
|
|
static void public_key_describe(const struct key *asymmetric_key,
|
|
struct seq_file *m)
|
|
{
|
|
struct public_key *key = asymmetric_key->payload.data[asym_crypto];
|
|
|
|
if (key)
|
|
seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
|
|
}
|
|
|
|
/*
|
|
* Destroy a public key algorithm key.
|
|
*/
|
|
void public_key_free(struct public_key *key)
|
|
{
|
|
if (key) {
|
|
kfree(key->key);
|
|
kfree(key);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(public_key_free);
|
|
|
|
/*
|
|
* Destroy a public key algorithm key.
|
|
*/
|
|
static void public_key_destroy(void *payload0, void *payload3)
|
|
{
|
|
public_key_free(payload0);
|
|
public_key_signature_free(payload3);
|
|
}
|
|
|
|
/*
|
|
* Verify a signature using a public key.
|
|
*/
|
|
int public_key_verify_signature(const struct public_key *pkey,
|
|
const struct public_key_signature *sig)
|
|
{
|
|
struct crypto_wait cwait;
|
|
struct crypto_akcipher *tfm;
|
|
struct akcipher_request *req;
|
|
struct scatterlist sig_sg, digest_sg;
|
|
const char *alg_name;
|
|
char alg_name_buf[CRYPTO_MAX_ALG_NAME];
|
|
void *output;
|
|
unsigned int outlen;
|
|
int ret;
|
|
|
|
pr_devel("==>%s()\n", __func__);
|
|
|
|
BUG_ON(!pkey);
|
|
BUG_ON(!sig);
|
|
BUG_ON(!sig->s);
|
|
|
|
if (!sig->digest)
|
|
return -ENOPKG;
|
|
|
|
alg_name = sig->pkey_algo;
|
|
if (strcmp(sig->pkey_algo, "rsa") == 0) {
|
|
/* The data wangled by the RSA algorithm is typically padded
|
|
* and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
|
|
* sec 8.2].
|
|
*/
|
|
if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
|
|
"pkcs1pad(rsa,%s)", sig->hash_algo
|
|
) >= CRYPTO_MAX_ALG_NAME)
|
|
return -EINVAL;
|
|
alg_name = alg_name_buf;
|
|
}
|
|
|
|
tfm = crypto_alloc_akcipher(alg_name, 0, 0);
|
|
if (IS_ERR(tfm))
|
|
return PTR_ERR(tfm);
|
|
|
|
ret = -ENOMEM;
|
|
req = akcipher_request_alloc(tfm, GFP_KERNEL);
|
|
if (!req)
|
|
goto error_free_tfm;
|
|
|
|
ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
|
|
if (ret)
|
|
goto error_free_req;
|
|
|
|
ret = -ENOMEM;
|
|
outlen = crypto_akcipher_maxsize(tfm);
|
|
output = kmalloc(outlen, GFP_KERNEL);
|
|
if (!output)
|
|
goto error_free_req;
|
|
|
|
sg_init_one(&sig_sg, sig->s, sig->s_size);
|
|
sg_init_one(&digest_sg, output, outlen);
|
|
akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
|
|
outlen);
|
|
crypto_init_wait(&cwait);
|
|
akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
|
|
CRYPTO_TFM_REQ_MAY_SLEEP,
|
|
crypto_req_done, &cwait);
|
|
|
|
/* Perform the verification calculation. This doesn't actually do the
|
|
* verification, but rather calculates the hash expected by the
|
|
* signature and returns that to us.
|
|
*/
|
|
ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
|
|
if (ret)
|
|
goto out_free_output;
|
|
|
|
/* Do the actual verification step. */
|
|
if (req->dst_len != sig->digest_size ||
|
|
memcmp(sig->digest, output, sig->digest_size) != 0)
|
|
ret = -EKEYREJECTED;
|
|
|
|
out_free_output:
|
|
kfree(output);
|
|
error_free_req:
|
|
akcipher_request_free(req);
|
|
error_free_tfm:
|
|
crypto_free_akcipher(tfm);
|
|
pr_devel("<==%s() = %d\n", __func__, ret);
|
|
if (WARN_ON_ONCE(ret > 0))
|
|
ret = -EINVAL;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(public_key_verify_signature);
|
|
|
|
static int public_key_verify_signature_2(const struct key *key,
|
|
const struct public_key_signature *sig)
|
|
{
|
|
const struct public_key *pk = key->payload.data[asym_crypto];
|
|
return public_key_verify_signature(pk, sig);
|
|
}
|
|
|
|
/*
|
|
* Public key algorithm asymmetric key subtype
|
|
*/
|
|
struct asymmetric_key_subtype public_key_subtype = {
|
|
.owner = THIS_MODULE,
|
|
.name = "public_key",
|
|
.name_len = sizeof("public_key") - 1,
|
|
.describe = public_key_describe,
|
|
.destroy = public_key_destroy,
|
|
.verify_signature = public_key_verify_signature_2,
|
|
};
|
|
EXPORT_SYMBOL_GPL(public_key_subtype);
|