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![David Howells](/assets/img/avatar_default.png)
Implement the encrypt, decrypt and sign operations for the software asymmetric key subtype. This mostly involves offloading the call to the crypto layer. Note that the decrypt and sign operations require a private key to be supplied. Encrypt (and also verify) will work with either a public or a private key. A public key can be supplied with an X.509 certificate and a private key can be supplied using a PKCS#8 blob: # j=`openssl pkcs8 -in ~/pkcs7/firmwarekey2.priv -topk8 -nocrypt -outform DER | keyctl padd asymmetric foo @s` # keyctl pkey_query $j - enc=pkcs1 key_size=4096 max_data_size=512 max_sig_size=512 max_enc_size=512 max_dec_size=512 encrypt=y decrypt=y sign=y verify=y # keyctl pkey_encrypt $j 0 data enc=pkcs1 >/tmp/enc # keyctl pkey_decrypt $j 0 /tmp/enc enc=pkcs1 >/tmp/dec # cmp data /tmp/dec # keyctl pkey_sign $j 0 data enc=pkcs1 hash=sha1 >/tmp/sig # keyctl pkey_verify $j 0 data /tmp/sig enc=pkcs1 hash=sha1 # Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: Marcel Holtmann <marcel@holtmann.org> Reviewed-by: Denis Kenzior <denkenz@gmail.com> Tested-by: Denis Kenzior <denkenz@gmail.com> Signed-off-by: James Morris <james.morris@microsoft.com>
327 lines
8.1 KiB
C
327 lines
8.1 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_DESCRIPTION("In-software asymmetric public-key subtype");
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MODULE_AUTHOR("Red Hat, Inc.");
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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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/*
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* Determine the crypto algorithm name.
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*/
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static
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int software_key_determine_akcipher(const char *encoding,
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const char *hash_algo,
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const struct public_key *pkey,
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char alg_name[CRYPTO_MAX_ALG_NAME])
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{
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int n;
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if (strcmp(encoding, "pkcs1") == 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 (!hash_algo)
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n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
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"pkcs1pad(%s)",
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pkey->pkey_algo);
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else
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n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
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"pkcs1pad(%s,%s)",
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pkey->pkey_algo, hash_algo);
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return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
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}
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if (strcmp(encoding, "raw") == 0) {
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strcpy(alg_name, pkey->pkey_algo);
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return 0;
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}
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return -ENOPKG;
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}
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/*
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* Query information about a key.
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*/
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static int software_key_query(const struct kernel_pkey_params *params,
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struct kernel_pkey_query *info)
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{
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struct crypto_akcipher *tfm;
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struct public_key *pkey = params->key->payload.data[asym_crypto];
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char alg_name[CRYPTO_MAX_ALG_NAME];
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int ret, len;
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ret = software_key_determine_akcipher(params->encoding,
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params->hash_algo,
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pkey, alg_name);
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if (ret < 0)
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return ret;
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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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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm,
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pkey->key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm,
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pkey->key, pkey->keylen);
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if (ret < 0)
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goto error_free_tfm;
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len = crypto_akcipher_maxsize(tfm);
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info->key_size = len * 8;
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info->max_data_size = len;
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info->max_sig_size = len;
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info->max_enc_size = len;
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info->max_dec_size = len;
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info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
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KEYCTL_SUPPORTS_VERIFY);
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if (pkey->key_is_private)
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info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
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KEYCTL_SUPPORTS_SIGN);
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ret = 0;
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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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/*
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* Do encryption, decryption and signing ops.
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*/
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static int software_key_eds_op(struct kernel_pkey_params *params,
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const void *in, void *out)
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{
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const struct public_key *pkey = params->key->payload.data[asym_crypto];
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struct akcipher_request *req;
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struct crypto_akcipher *tfm;
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struct crypto_wait cwait;
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struct scatterlist in_sg, out_sg;
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char alg_name[CRYPTO_MAX_ALG_NAME];
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int ret;
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pr_devel("==>%s()\n", __func__);
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ret = software_key_determine_akcipher(params->encoding,
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params->hash_algo,
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pkey, alg_name);
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if (ret < 0)
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return ret;
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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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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm,
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pkey->key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm,
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pkey->key, pkey->keylen);
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if (ret)
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goto error_free_req;
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sg_init_one(&in_sg, in, params->in_len);
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sg_init_one(&out_sg, out, params->out_len);
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akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
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params->out_len);
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crypto_init_wait(&cwait);
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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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crypto_req_done, &cwait);
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/* Perform the encryption calculation. */
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switch (params->op) {
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case kernel_pkey_encrypt:
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ret = crypto_akcipher_encrypt(req);
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break;
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case kernel_pkey_decrypt:
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ret = crypto_akcipher_decrypt(req);
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break;
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case kernel_pkey_sign:
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ret = crypto_akcipher_sign(req);
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break;
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default:
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BUG();
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}
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ret = crypto_wait_req(ret, &cwait);
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if (ret == 0)
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ret = req->dst_len;
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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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/*
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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 crypto_wait cwait;
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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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char alg_name[CRYPTO_MAX_ALG_NAME];
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void *output;
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unsigned int outlen;
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int ret;
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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->s);
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ret = software_key_determine_akcipher(sig->encoding,
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sig->hash_algo,
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pkey, alg_name);
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if (ret < 0)
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return ret;
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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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ret = -ENOMEM;
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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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if (pkey->key_is_private)
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ret = crypto_akcipher_set_priv_key(tfm,
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pkey->key, pkey->keylen);
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else
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ret = crypto_akcipher_set_pub_key(tfm,
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pkey->key, pkey->keylen);
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if (ret)
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goto error_free_req;
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ret = -ENOMEM;
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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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crypto_init_wait(&cwait);
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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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crypto_req_done, &cwait);
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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_wait_req(crypto_akcipher_verify(req), &cwait);
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if (ret)
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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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if (WARN_ON_ONCE(ret > 0))
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ret = -EINVAL;
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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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.query = software_key_query,
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.eds_op = software_key_eds_op,
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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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