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Diffstat (limited to 'contrib/unbound/util/random.c')
-rw-r--r-- | contrib/unbound/util/random.c | 276 |
1 files changed, 276 insertions, 0 deletions
diff --git a/contrib/unbound/util/random.c b/contrib/unbound/util/random.c new file mode 100644 index 0000000..8a24ff0 --- /dev/null +++ b/contrib/unbound/util/random.c @@ -0,0 +1,276 @@ +/* + * util/random.c - thread safe random generator, which is reasonably secure. + * + * Copyright (c) 2007, NLnet Labs. All rights reserved. + * + * This software is open source. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 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. + * + * Neither the name of the NLNET LABS nor the names of its contributors may + * be used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "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 COPYRIGHT + * HOLDER OR CONTRIBUTORS 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. + */ + +/** + * \file + * Thread safe random functions. Similar to arc4random() with an explicit + * initialisation routine. + * + * The code in this file is based on arc4random from + * openssh-4.0p1/openbsd-compat/bsd-arc4random.c + * That code is also BSD licensed. Here is their statement: + * + * Copyright (c) 1996, David Mazieres <dm@uun.org> + * Copyright (c) 2008, Damien Miller <djm@openbsd.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#include "config.h" +#include "util/random.h" +#include "util/log.h" +#include <time.h> +#ifdef HAVE_SSL +#include <openssl/rand.h> +#include <openssl/rc4.h> +#include <openssl/err.h> +#elif defined(HAVE_NSS) +/* nspr4 */ +#include "prerror.h" +/* nss3 */ +#include "secport.h" +#include "pk11pub.h" +#endif + +/** + * Max random value. Similar to RAND_MAX, but more portable + * (mingw uses only 15 bits random). + */ +#define MAX_VALUE 0x7fffffff + +#ifdef HAVE_SSL +/** + * Struct with per-thread random state. + * Keeps SSL types away from the header file. + */ +struct ub_randstate { + /** key used for arc4random generation */ + RC4_KEY rc4; + /** keeps track of key usage */ + int rc4_ready; +}; + +/** Size of key to use (must be multiple of 8) */ +#define SEED_SIZE 24 + +/** Number of bytes to reseed after */ +#define REKEY_BYTES (1 << 24) + +/* (re)setup system seed */ +void +ub_systemseed(unsigned int seed) +{ + /* RAND_ is threadsafe, by the way */ + if(!RAND_status()) { + /* try to seed it */ + unsigned char buf[256]; + unsigned int v = seed; + size_t i; + for(i=0; i<256/sizeof(seed); i++) { + memmove(buf+i*sizeof(seed), &v, sizeof(seed)); + v = v*seed + (unsigned int)i; + } + RAND_seed(buf, 256); + if(!RAND_status()) { + log_err("Random generator has no entropy " + "(error %ld)", ERR_get_error()); + } else { + verbose(VERB_OPS, "openssl has no entropy, " + "seeding with time and pid"); + } + } +} + +/** reseed random generator */ +static void +ub_arc4random_stir(struct ub_randstate* s, struct ub_randstate* from) +{ + /* not as unsigned char, but longerint so that it is + aligned properly on alignment sensitive platforms */ + uint64_t rand_buf[SEED_SIZE/sizeof(uint64_t)]; + int i; + + memset(&s->rc4, 0, sizeof(s->rc4)); + memset(rand_buf, 0xc, sizeof(rand_buf)); + if (from) { + uint8_t* rbuf = (uint8_t*)rand_buf; + for(i=0; i<SEED_SIZE; i++) + rbuf[i] = (uint8_t)ub_random(from); + } else { + if(!RAND_status()) + ub_systemseed((unsigned)getpid()^(unsigned)time(NULL)); + if (RAND_bytes((unsigned char*)rand_buf, + (int)sizeof(rand_buf)) <= 0) { + /* very unlikely that this happens, since we seeded + * above, if it does; complain and keep going */ + log_err("Couldn't obtain random bytes (error %ld)", + ERR_get_error()); + s->rc4_ready = 256; + return; + } + } +#ifdef HAVE_FIPS_MODE + if(FIPS_mode()) { + /* RC4 is not allowed, get some trustworthy randomness */ + /* double certainty here, this routine should not be + * called in FIPS_mode */ + memset(rand_buf, 0, sizeof(rand_buf)); + s->rc4_ready = REKEY_BYTES; + return; + } +#endif /* FIPS_MODE */ + RC4_set_key(&s->rc4, SEED_SIZE, (unsigned char*)rand_buf); + + /* + * Discard early keystream, as per recommendations in: + * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps + */ + for(i = 0; i <= 256; i += sizeof(rand_buf)) + RC4(&s->rc4, sizeof(rand_buf), (unsigned char*)rand_buf, + (unsigned char*)rand_buf); + + memset(rand_buf, 0, sizeof(rand_buf)); + + s->rc4_ready = REKEY_BYTES; +} + +struct ub_randstate* +ub_initstate(unsigned int seed, struct ub_randstate* from) +{ + struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s)); + if(!s) { + log_err("malloc failure in random init"); + return NULL; + } + ub_systemseed(seed); +#ifdef HAVE_FIPS_MODE + if(!FIPS_mode()) +#endif + ub_arc4random_stir(s, from); + return s; +} + +long int +ub_random(struct ub_randstate* s) +{ + unsigned int r = 0; +#ifdef HAVE_FIPS_MODE + if(FIPS_mode()) { + /* RC4 is not allowed, get some trustworthy randomness */ + /* we use pseudo bytes: it tries to return secure randomness + * but returns 'something' if that fails. We need something + * else if it fails, because we cannot block here */ + if(RAND_pseudo_bytes((unsigned char*)&r, (int)sizeof(r)) + == -1) { + log_err("FIPSmode, no arc4random but RAND failed " + "(error %ld)", ERR_get_error()); + } + return (long int)((r) % (((unsigned)MAX_VALUE + 1))); + } +#endif /* FIPS_MODE */ + if (s->rc4_ready <= 0) { + ub_arc4random_stir(s, NULL); + } + + RC4(&s->rc4, sizeof(r), + (unsigned char *)&r, (unsigned char *)&r); + s->rc4_ready -= sizeof(r); + return (long int)((r) % (((unsigned)MAX_VALUE + 1))); +} + +#elif defined(HAVE_NSS) + +/* not much to remember for NSS since we use its pk11_random, placeholder */ +struct ub_randstate { + int ready; +}; + +void ub_systemseed(unsigned int ATTR_UNUSED(seed)) +{ +} + +struct ub_randstate* ub_initstate(unsigned int ATTR_UNUSED(seed), + struct ub_randstate* ATTR_UNUSED(from)) +{ + struct ub_randstate* s = (struct ub_randstate*)calloc(1, sizeof(*s)); + if(!s) { + log_err("malloc failure in random init"); + return NULL; + } + return s; +} + +long int ub_random(struct ub_randstate* ATTR_UNUSED(state)) +{ + long int x; + /* random 31 bit value. */ + SECStatus s = PK11_GenerateRandom((unsigned char*)&x, (int)sizeof(x)); + if(s != SECSuccess) { + log_err("PK11_GenerateRandom error: %s", + PORT_ErrorToString(PORT_GetError())); + } + return x & MAX_VALUE; +} + +#endif /* HAVE_SSL or HAVE_NSS */ + +long int +ub_random_max(struct ub_randstate* state, long int x) +{ + /* make sure we fetch in a range that is divisible by x. ignore + * values from d .. MAX_VALUE, instead draw a new number */ + long int d = MAX_VALUE - (MAX_VALUE % x); /* d is divisible by x */ + long int v = ub_random(state); + while(d <= v) + v = ub_random(state); + return (v % x); +} + +void +ub_randfree(struct ub_randstate* s) +{ + if(s) + free(s); + /* user app must do RAND_cleanup(); */ +} |