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![David Howells](/assets/img/avatar_default.png)
Allow authentication data to be stored in an asymmetric key in the 4th element of the key payload and provide a way for it to be destroyed. For the public key subtype, this will be a public_key_signature struct. Signed-off-by: David Howells <dhowells@redhat.com>
184 lines
4.6 KiB
C
184 lines
4.6 KiB
C
/* In-software asymmetric public-key crypto subtype
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*
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* See Documentation/crypto/asymmetric-keys.txt
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#define pr_fmt(fmt) "PKEY: "fmt
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#include <linux/module.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/scatterlist.h>
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#include <keys/asymmetric-subtype.h>
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#include <crypto/public_key.h>
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#include <crypto/akcipher.h>
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MODULE_LICENSE("GPL");
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/*
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* Provide a part of a description of the key for /proc/keys.
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*/
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static void public_key_describe(const struct key *asymmetric_key,
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struct seq_file *m)
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{
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struct public_key *key = asymmetric_key->payload.data[asym_crypto];
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if (key)
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seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
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}
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/*
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* Destroy a public key algorithm key.
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*/
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void public_key_free(struct public_key *key)
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{
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if (key) {
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kfree(key->key);
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kfree(key);
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}
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}
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EXPORT_SYMBOL_GPL(public_key_free);
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/*
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* Destroy a public key algorithm key.
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*/
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static void public_key_destroy(void *payload0, void *payload3)
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{
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public_key_free(payload0);
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public_key_signature_free(payload3);
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}
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struct public_key_completion {
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struct completion completion;
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int err;
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};
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static void public_key_verify_done(struct crypto_async_request *req, int err)
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{
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struct public_key_completion *compl = req->data;
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if (err == -EINPROGRESS)
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return;
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compl->err = err;
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complete(&compl->completion);
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}
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/*
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* Verify a signature using a public key.
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*/
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int public_key_verify_signature(const struct public_key *pkey,
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const struct public_key_signature *sig)
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{
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struct public_key_completion compl;
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struct crypto_akcipher *tfm;
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struct akcipher_request *req;
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struct scatterlist sig_sg, digest_sg;
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const char *alg_name;
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char alg_name_buf[CRYPTO_MAX_ALG_NAME];
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void *output;
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unsigned int outlen;
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int ret = -ENOMEM;
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pr_devel("==>%s()\n", __func__);
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BUG_ON(!pkey);
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BUG_ON(!sig);
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BUG_ON(!sig->digest);
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BUG_ON(!sig->s);
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alg_name = sig->pkey_algo;
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if (strcmp(sig->pkey_algo, "rsa") == 0) {
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/* The data wangled by the RSA algorithm is typically padded
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* and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
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* sec 8.2].
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*/
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if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
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"pkcs1pad(rsa,%s)", sig->hash_algo
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) >= CRYPTO_MAX_ALG_NAME)
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return -EINVAL;
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alg_name = alg_name_buf;
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}
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tfm = crypto_alloc_akcipher(alg_name, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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req = akcipher_request_alloc(tfm, GFP_KERNEL);
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if (!req)
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goto error_free_tfm;
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ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
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if (ret)
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goto error_free_req;
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outlen = crypto_akcipher_maxsize(tfm);
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output = kmalloc(outlen, GFP_KERNEL);
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if (!output)
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goto error_free_req;
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sg_init_one(&sig_sg, sig->s, sig->s_size);
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sg_init_one(&digest_sg, output, outlen);
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akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
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outlen);
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init_completion(&compl.completion);
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akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
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CRYPTO_TFM_REQ_MAY_SLEEP,
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public_key_verify_done, &compl);
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/* Perform the verification calculation. This doesn't actually do the
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* verification, but rather calculates the hash expected by the
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* signature and returns that to us.
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*/
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ret = crypto_akcipher_verify(req);
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if (ret == -EINPROGRESS) {
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wait_for_completion(&compl.completion);
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ret = compl.err;
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}
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if (ret < 0)
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goto out_free_output;
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/* Do the actual verification step. */
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if (req->dst_len != sig->digest_size ||
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memcmp(sig->digest, output, sig->digest_size) != 0)
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ret = -EKEYREJECTED;
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out_free_output:
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kfree(output);
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error_free_req:
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akcipher_request_free(req);
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error_free_tfm:
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crypto_free_akcipher(tfm);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(public_key_verify_signature);
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static int public_key_verify_signature_2(const struct key *key,
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const struct public_key_signature *sig)
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{
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const struct public_key *pk = key->payload.data[asym_crypto];
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return public_key_verify_signature(pk, sig);
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}
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/*
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* Public key algorithm asymmetric key subtype
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*/
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struct asymmetric_key_subtype public_key_subtype = {
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.owner = THIS_MODULE,
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.name = "public_key",
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.name_len = sizeof("public_key") - 1,
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.describe = public_key_describe,
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.destroy = public_key_destroy,
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.verify_signature = public_key_verify_signature_2,
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};
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EXPORT_SYMBOL_GPL(public_key_subtype);
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