/* $OpenBSD: mac.c,v 1.24 2013/06/03 00:03:18 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 "includes.h" #include #include #include #include #include #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" #include "openbsd-compat/openssl-compat.h" #define SSH_EVP 1 /* OpenSSL EVP-based MAC */ #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ #define SSH_UMAC128 3 struct macalg { 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 */ int etm; /* Encrypt-then-MAC */ }; static const struct macalg macs[] = { /* Encrypt-and-MAC (encrypt-and-authenticate) variants */ { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 }, { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 }, #ifdef HAVE_EVP_SHA256 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 }, { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 }, #endif { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 }, { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 }, { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 }, { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 }, /* Encrypt-then-MAC variants */ { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 }, { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 }, #ifdef HAVE_EVP_SHA256 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 }, { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 }, #endif { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 }, { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 }, { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 }, { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 }, { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 }, { NULL, 0, NULL, 0, 0, 0, 0 } }; /* Returns a comma-separated list of supported MACs. */ char * mac_alg_list(void) { char *ret = NULL; size_t nlen, rlen = 0; const struct macalg *m; for (m = macs; m->name != NULL; m++) { if (ret != NULL) ret[rlen++] = '\n'; nlen = strlen(m->name); ret = xrealloc(ret, 1, rlen + nlen + 2); memcpy(ret + rlen, m->name, nlen + 1); rlen += nlen; } return ret; } static void mac_setup_by_alg(Mac *mac, const struct macalg *macalg) { int evp_len; mac->type = macalg->type; if (mac->type == SSH_EVP) { mac->evp_md = macalg->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 = macalg->len / 8; mac->key_len = macalg->key_len / 8; mac->umac_ctx = NULL; } if (macalg->truncatebits != 0) mac->mac_len = macalg->truncatebits / 8; mac->etm = macalg->etm; } int mac_setup(Mac *mac, char *name) { const struct macalg *m; for (m = macs; m->name != NULL; m++) { if (strcmp(name, m->name) != 0) continue; if (mac != NULL) mac_setup_by_alg(mac, m); 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; case SSH_UMAC128: mac->umac_ctx = umac128_new(mac->key); return 0; default: return -1; } } u_char * mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) { static union { u_char m[EVP_MAX_MD_SIZE]; u_int64_t for_align; } u; u_char b[4], nonce[8]; if (mac->mac_len > sizeof(u)) fatal("mac_compute: mac too long %u %lu", mac->mac_len, (u_long)sizeof(u)); 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, u.m, NULL); break; case SSH_UMAC: put_u64(nonce, seqno); umac_update(mac->umac_ctx, data, datalen); umac_final(mac->umac_ctx, u.m, nonce); break; case SSH_UMAC128: put_u64(nonce, seqno); umac128_update(mac->umac_ctx, data, datalen); umac128_final(mac->umac_ctx, u.m, nonce); break; default: fatal("mac_compute: unknown MAC type"); } return (u.m); } void mac_clear(Mac *mac) { if (mac->type == SSH_UMAC) { if (mac->umac_ctx != NULL) umac_delete(mac->umac_ctx); } else if (mac->type == SSH_UMAC128) { if (mac->umac_ctx != NULL) umac128_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); free(maclist); return (0); } else { debug3("mac ok: %s [%s]", p, names); } } debug3("macs ok: [%s]", names); free(maclist); return (1); }