6a228a1b19
MFC after: 3 weeks
403 lines
10 KiB
C
403 lines
10 KiB
C
/*-
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* Copyright (c) 2010 The FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed by Shteryana Sotirova Shopova under
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* sponsorship from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <stdarg.h>
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#ifdef HAVE_STDINT_H
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#include <stdint.h>
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#elif defined(HAVE_INTTYPES_H)
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#include <inttypes.h>
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#endif
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#include <string.h>
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#include <ctype.h>
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#include <errno.h>
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#include <netinet/in.h>
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#ifdef HAVE_LIBCRYPTO
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#include <openssl/evp.h>
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#endif
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#include "asn1.h"
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#include "snmp.h"
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#include "snmppriv.h"
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#define SNMP_PRIV_AES_IV_SIZ 16
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#define SNMP_EXTENDED_KEY_SIZ 64
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#define SNMP_AUTH_KEY_LOOPCNT 1048576
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#define SNMP_AUTH_BUF_SIZE 72
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static const uint8_t ipad = 0x36;
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static const uint8_t opad = 0x5c;
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#ifdef HAVE_LIBCRYPTO
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static int32_t
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snmp_digest_init(const struct snmp_user *user, EVP_MD_CTX *ctx,
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const EVP_MD **dtype, uint32_t *keylen)
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{
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if (user->auth_proto == SNMP_AUTH_HMAC_MD5) {
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*dtype = EVP_md5();
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*keylen = SNMP_AUTH_HMACMD5_KEY_SIZ;
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} else if (user->auth_proto == SNMP_AUTH_HMAC_SHA) {
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*dtype = EVP_sha1();
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*keylen = SNMP_AUTH_HMACSHA_KEY_SIZ;
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} else if (user->auth_proto == SNMP_AUTH_NOAUTH)
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return (0);
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else {
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snmp_error("unknown authentication option - %d",
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user->auth_proto);
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return (-1);
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}
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if (EVP_DigestInit(ctx, *dtype) != 1)
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return (-1);
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return (1);
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}
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enum snmp_code
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snmp_pdu_calc_digest(const struct snmp_pdu *pdu, uint8_t *digest)
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{
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uint8_t md[EVP_MAX_MD_SIZE], extkey[SNMP_EXTENDED_KEY_SIZ];
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uint8_t key1[SNMP_EXTENDED_KEY_SIZ], key2[SNMP_EXTENDED_KEY_SIZ];
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uint32_t i, keylen, olen;
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int32_t err;
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const EVP_MD *dtype;
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EVP_MD_CTX ctx;
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err = snmp_digest_init(&pdu->user, &ctx, &dtype, &keylen);
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if (err < 0)
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return (SNMP_CODE_BADDIGEST);
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else if (err == 0)
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return (SNMP_CODE_OK);
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memset(pdu->digest_ptr, 0, sizeof(pdu->msg_digest));
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memcpy(extkey, pdu->user.auth_key, keylen);
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memset(extkey + keylen, 0, sizeof(extkey) - keylen);
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for (i = 0; i < SNMP_EXTENDED_KEY_SIZ; i++) {
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key1[i] = extkey[i] ^ ipad;
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key2[i] = extkey[i] ^ opad;
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}
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if (EVP_DigestUpdate(&ctx, key1, SNMP_EXTENDED_KEY_SIZ) != 1 ||
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EVP_DigestUpdate(&ctx, pdu->outer_ptr, pdu->outer_len) != 1 ||
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EVP_DigestFinal(&ctx, md, &olen) != 1)
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goto failed;
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if (EVP_DigestInit(&ctx, dtype) != 1 ||
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EVP_DigestUpdate(&ctx, key2, SNMP_EXTENDED_KEY_SIZ) != 1 ||
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EVP_DigestUpdate(&ctx, md, olen) != 1 ||
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EVP_DigestFinal(&ctx, md, &olen) != 1)
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goto failed;
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if (olen < SNMP_USM_AUTH_SIZE) {
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snmp_error("bad digest size - %d", olen);
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_BADDIGEST);
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}
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memcpy(digest, md, SNMP_USM_AUTH_SIZE);
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_OK);
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failed:
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_BADDIGEST);
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}
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static int32_t
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snmp_pdu_cipher_init(const struct snmp_pdu *pdu, int32_t len,
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const EVP_CIPHER **ctype, uint8_t *piv)
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{
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int i;
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uint32_t netint;
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if (pdu->user.priv_proto == SNMP_PRIV_DES) {
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if (len % 8 != 0)
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return (-1);
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*ctype = EVP_des_cbc();
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memcpy(piv, pdu->msg_salt, sizeof(pdu->msg_salt));
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for (i = 0; i < 8; i++)
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piv[i] = piv[i] ^ pdu->user.priv_key[8 + i];
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} else if (pdu->user.priv_proto == SNMP_PRIV_AES) {
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*ctype = EVP_aes_128_cfb128();
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netint = htonl(pdu->engine.engine_boots);
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memcpy(piv, &netint, sizeof(netint));
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piv += sizeof(netint);
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netint = htonl(pdu->engine.engine_time);
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memcpy(piv, &netint, sizeof(netint));
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piv += sizeof(netint);
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memcpy(piv, pdu->msg_salt, sizeof(pdu->msg_salt));
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} else if (pdu->user.priv_proto == SNMP_PRIV_NOPRIV)
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return (0);
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else {
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snmp_error("unknown privacy option - %d", pdu->user.priv_proto);
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return (-1);
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}
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return (1);
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}
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enum snmp_code
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snmp_pdu_encrypt(const struct snmp_pdu *pdu)
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{
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int32_t err, olen;
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uint8_t iv[SNMP_PRIV_AES_IV_SIZ];
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const EVP_CIPHER *ctype;
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EVP_CIPHER_CTX ctx;
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err = snmp_pdu_cipher_init(pdu, pdu->scoped_len, &ctype, iv);
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if (err < 0)
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return (SNMP_CODE_EDECRYPT);
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else if (err == 0)
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return (SNMP_CODE_OK);
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if (EVP_EncryptInit(&ctx, ctype, pdu->user.priv_key, iv) != 1)
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return (SNMP_CODE_FAILED);
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if (EVP_EncryptUpdate(&ctx, pdu->scoped_ptr, &olen, pdu->scoped_ptr,
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pdu->scoped_len) != 1 ||
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EVP_EncryptFinal(&ctx, pdu->scoped_ptr + olen, &olen) != 1) {
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EVP_CIPHER_CTX_cleanup(&ctx);
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return (SNMP_CODE_FAILED);
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}
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EVP_CIPHER_CTX_cleanup(&ctx);
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return (SNMP_CODE_OK);
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}
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enum snmp_code
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snmp_pdu_decrypt(const struct snmp_pdu *pdu)
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{
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int32_t err, olen;
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uint8_t iv[SNMP_PRIV_AES_IV_SIZ];
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const EVP_CIPHER *ctype;
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EVP_CIPHER_CTX ctx;
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err = snmp_pdu_cipher_init(pdu, pdu->scoped_len, &ctype, iv);
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if (err < 0)
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return (SNMP_CODE_EDECRYPT);
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else if (err == 0)
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return (SNMP_CODE_OK);
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if (EVP_DecryptInit(&ctx, ctype, pdu->user.priv_key, iv) != 1 ||
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EVP_CIPHER_CTX_set_padding(&ctx, 0) != 1)
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return (SNMP_CODE_EDECRYPT);
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if (EVP_DecryptUpdate(&ctx, pdu->scoped_ptr, &olen, pdu->scoped_ptr,
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pdu->scoped_len) != 1 ||
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EVP_DecryptFinal(&ctx, pdu->scoped_ptr + olen, &olen) != 1) {
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EVP_CIPHER_CTX_cleanup(&ctx);
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return (SNMP_CODE_EDECRYPT);
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}
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EVP_CIPHER_CTX_cleanup(&ctx);
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return (SNMP_CODE_OK);
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}
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/* [RFC 3414] - A.2. Password to Key Algorithm */
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enum snmp_code
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snmp_passwd_to_keys(struct snmp_user *user, char *passwd)
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{
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int err, loop, i, pwdlen;
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uint32_t keylen, olen;
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const EVP_MD *dtype;
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EVP_MD_CTX ctx;
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uint8_t authbuf[SNMP_AUTH_BUF_SIZE];
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if (passwd == NULL || user == NULL)
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return (SNMP_CODE_FAILED);
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err = snmp_digest_init(user, &ctx, &dtype, &keylen);
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if (err < 0)
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return (SNMP_CODE_BADDIGEST);
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else if (err == 0)
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return (SNMP_CODE_OK);
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memset(user->auth_key, 0, sizeof(user->auth_key));
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pwdlen = strlen(passwd);
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for (loop = 0; loop < SNMP_AUTH_KEY_LOOPCNT; loop += i) {
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for (i = 0; i < SNMP_EXTENDED_KEY_SIZ; i++)
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authbuf[i] = passwd[(loop + i) % pwdlen];
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if (EVP_DigestUpdate(&ctx, authbuf, SNMP_EXTENDED_KEY_SIZ) != 1)
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goto failed;
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}
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if (EVP_DigestFinal(&ctx, user->auth_key, &olen) != 1)
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goto failed;
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_OK);
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failed:
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_BADDIGEST);
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}
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/* [RFC 3414] - 2.6. Key Localization Algorithm */
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enum snmp_code
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snmp_get_local_keys(struct snmp_user *user, uint8_t *eid, uint32_t elen)
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{
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int err;
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uint32_t keylen, olen;
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const EVP_MD *dtype;
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EVP_MD_CTX ctx;
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uint8_t authbuf[SNMP_AUTH_BUF_SIZE];
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if (user == NULL || eid == NULL || elen > SNMP_ENGINE_ID_SIZ)
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return (SNMP_CODE_FAILED);
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memset(user->priv_key, 0, sizeof(user->priv_key));
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memset(authbuf, 0, sizeof(authbuf));
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err = snmp_digest_init(user, &ctx, &dtype, &keylen);
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if (err < 0)
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return (SNMP_CODE_BADDIGEST);
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else if (err == 0)
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return (SNMP_CODE_OK);
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memcpy(authbuf, user->auth_key, keylen);
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memcpy(authbuf + keylen, eid, elen);
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memcpy(authbuf + keylen + elen, user->auth_key, keylen);
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if (EVP_DigestUpdate(&ctx, authbuf, 2 * keylen + elen) != 1 ||
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EVP_DigestFinal(&ctx, user->auth_key, &olen) != 1) {
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_BADDIGEST);
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}
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EVP_MD_CTX_cleanup(&ctx);
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if (user->priv_proto != SNMP_PRIV_NOPRIV)
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memcpy(user->priv_key, user->auth_key, sizeof(user->priv_key));
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return (SNMP_CODE_OK);
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}
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enum snmp_code
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snmp_calc_keychange(struct snmp_user *user, uint8_t *keychange)
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{
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int32_t err, rvalue[SNMP_AUTH_HMACSHA_KEY_SIZ / 4];
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uint32_t i, keylen, olen;
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const EVP_MD *dtype;
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EVP_MD_CTX ctx;
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err = snmp_digest_init(user, &ctx, &dtype, &keylen);
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if (err < 0)
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return (SNMP_CODE_BADDIGEST);
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else if (err == 0)
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return (SNMP_CODE_OK);
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for (i = 0; i < keylen / 4; i++)
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rvalue[i] = random();
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memcpy(keychange, user->auth_key, keylen);
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memcpy(keychange + keylen, rvalue, keylen);
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if (EVP_DigestUpdate(&ctx, keychange, 2 * keylen) != 1 ||
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EVP_DigestFinal(&ctx, keychange, &olen) != 1) {
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_BADDIGEST);
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}
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EVP_MD_CTX_cleanup(&ctx);
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return (SNMP_CODE_OK);
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}
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#else /* !HAVE_LIBCRYPTO */
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enum snmp_code
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snmp_pdu_calc_digest(const struct snmp_pdu *pdu, uint8_t *digest __unused)
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{
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if (pdu->user.auth_proto != SNMP_AUTH_NOAUTH)
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return (SNMP_CODE_BADSECLEVEL);
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return (SNMP_CODE_OK);
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}
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enum snmp_code
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snmp_pdu_encrypt(const struct snmp_pdu *pdu)
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{
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if (pdu->user.priv_proto != SNMP_PRIV_NOPRIV)
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return (SNMP_CODE_BADSECLEVEL);
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return (SNMP_CODE_OK);
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}
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enum snmp_code
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snmp_pdu_decrypt(const struct snmp_pdu *pdu)
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{
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if (pdu->user.priv_proto != SNMP_PRIV_NOPRIV)
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return (SNMP_CODE_BADSECLEVEL);
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return (SNMP_CODE_OK);
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}
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enum snmp_code
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snmp_passwd_to_keys(struct snmp_user *user, char *passwd __unused)
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{
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if (user->auth_proto == SNMP_AUTH_NOAUTH &&
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user->priv_proto == SNMP_PRIV_NOPRIV)
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return (SNMP_CODE_OK);
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errno = EPROTONOSUPPORT;
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return (SNMP_CODE_FAILED);
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}
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enum snmp_code
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snmp_get_local_keys(struct snmp_user *user, uint8_t *eid __unused,
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uint32_t elen __unused)
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{
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if (user->auth_proto == SNMP_AUTH_NOAUTH &&
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user->priv_proto == SNMP_PRIV_NOPRIV)
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return (SNMP_CODE_OK);
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errno = EPROTONOSUPPORT;
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return (SNMP_CODE_FAILED);
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}
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enum snmp_code
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snmp_calc_keychange(struct snmp_user *user __unused,
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uint8_t *keychange __unused)
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{
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errno = EPROTONOSUPPORT;
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return (SNMP_CODE_FAILED);
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}
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#endif /* HAVE_LIBCRYPTO */
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