/* $OpenBSD: mac.c,v 1.18 2012/06/28 05:07:45 dtucker Exp $ */ /* * Copyright (c) 2001 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <sys/types.h> #include <openssl/hmac.h> #include <string.h> #include <signal.h> #include "xmalloc.h" #include "log.h" #include "cipher.h" #include "buffer.h" #include "key.h" #include "kex.h" #include "mac.h" #include "misc.h" #include "umac.h" #define SSH_EVP 1 /* OpenSSL EVP-based MAC */ #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ struct { char *name; int type; const EVP_MD * (*mdfunc)(void); int truncatebits; /* truncate digest if != 0 */ int key_len; /* just for UMAC */ int len; /* just for UMAC */ } macs[] = { { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 }, { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 }, { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, -1, -1 }, { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, -1, -1 }, { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 }, { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 }, { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 }, { NULL, 0, NULL, 0, -1, -1 } }; static void mac_setup_by_id(Mac *mac, int which) { int evp_len; mac->type = macs[which].type; if (mac->type == SSH_EVP) { mac->evp_md = (*macs[which].mdfunc)(); if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) fatal("mac %s len %d", mac->name, evp_len); mac->key_len = mac->mac_len = (u_int)evp_len; } else { mac->mac_len = macs[which].len / 8; mac->key_len = macs[which].key_len / 8; mac->umac_ctx = NULL; } if (macs[which].truncatebits != 0) mac->mac_len = macs[which].truncatebits / 8; } int mac_setup(Mac *mac, char *name) { int i; for (i = 0; macs[i].name; i++) { if (strcmp(name, macs[i].name) == 0) { if (mac != NULL) mac_setup_by_id(mac, i); debug2("mac_setup: found %s", name); return (0); } } debug2("mac_setup: unknown %s", name); return (-1); } int mac_init(Mac *mac) { if (mac->key == NULL) fatal("mac_init: no key"); switch (mac->type) { case SSH_EVP: if (mac->evp_md == NULL) return -1; HMAC_CTX_init(&mac->evp_ctx); HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); return 0; case SSH_UMAC: mac->umac_ctx = umac_new(mac->key); return 0; default: return -1; } } u_char * mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) { static u_char m[EVP_MAX_MD_SIZE]; u_char b[4], nonce[8]; if (mac->mac_len > sizeof(m)) fatal("mac_compute: mac too long %u %lu", mac->mac_len, (u_long)sizeof(m)); switch (mac->type) { case SSH_EVP: put_u32(b, seqno); /* reset HMAC context */ HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); HMAC_Update(&mac->evp_ctx, b, sizeof(b)); HMAC_Update(&mac->evp_ctx, data, datalen); HMAC_Final(&mac->evp_ctx, m, NULL); break; case SSH_UMAC: put_u64(nonce, seqno); umac_update(mac->umac_ctx, data, datalen); umac_final(mac->umac_ctx, m, nonce); break; default: fatal("mac_compute: unknown MAC type"); } return (m); } void mac_clear(Mac *mac) { if (mac->type == SSH_UMAC) { if (mac->umac_ctx != NULL) umac_delete(mac->umac_ctx); } else if (mac->evp_md != NULL) HMAC_cleanup(&mac->evp_ctx); mac->evp_md = NULL; mac->umac_ctx = NULL; } /* XXX copied from ciphers_valid */ #define MAC_SEP "," int mac_valid(const char *names) { char *maclist, *cp, *p; if (names == NULL || strcmp(names, "") == 0) return (0); maclist = cp = xstrdup(names); for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; (p = strsep(&cp, MAC_SEP))) { if (mac_setup(NULL, p) < 0) { debug("bad mac %s [%s]", p, names); xfree(maclist); return (0); } else { debug3("mac ok: %s [%s]", p, names); } } debug3("macs ok: [%s]", names); xfree(maclist); return (1); }