5dfaa0d10b
Allow them to disable the EGD/profile access and the use of a random seed file. These facilities are not tenable when running in the kernel.
114 lines
3.5 KiB
C
114 lines
3.5 KiB
C
/*
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* Copyright (c) 1997 - 2008 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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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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*
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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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*
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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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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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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#include "krb5_locl.h"
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#define ENTROPY_NEEDED 128
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static HEIMDAL_MUTEX crypto_mutex = HEIMDAL_MUTEX_INITIALIZER;
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static int
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seed_something(void)
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{
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#ifndef NO_RANDFILE
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char buf[1024], seedfile[256];
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/* If there is a seed file, load it. But such a file cannot be trusted,
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so use 0 for the entropy estimate */
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if (RAND_file_name(seedfile, sizeof(seedfile))) {
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int fd;
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fd = open(seedfile, O_RDONLY | O_BINARY | O_CLOEXEC);
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if (fd >= 0) {
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ssize_t ret;
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rk_cloexec(fd);
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ret = read(fd, buf, sizeof(buf));
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if (ret > 0)
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RAND_add(buf, ret, 0.0);
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close(fd);
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} else
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seedfile[0] = '\0';
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} else
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seedfile[0] = '\0';
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#endif
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/* Calling RAND_status() will try to use /dev/urandom if it exists so
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we do not have to deal with it. */
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if (RAND_status() != 1) {
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#ifndef NO_RAND_EGD_METHOD
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krb5_context context;
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const char *p;
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/* Try using egd */
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if (!krb5_init_context(&context)) {
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p = krb5_config_get_string(context, NULL, "libdefaults",
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"egd_socket", NULL);
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if (p != NULL)
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RAND_egd_bytes(p, ENTROPY_NEEDED);
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krb5_free_context(context);
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}
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#else
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/* TODO: Once a Windows CryptoAPI RAND method is defined, we
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can use that and failover to another method. */
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#endif
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}
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if (RAND_status() == 1) {
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#ifndef NO_RANDFILE
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/* Update the seed file */
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if (seedfile[0])
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RAND_write_file(seedfile);
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#endif
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return 0;
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} else
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return -1;
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}
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KRB5_LIB_FUNCTION void KRB5_LIB_CALL
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krb5_generate_random_block(void *buf, size_t len)
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{
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static int rng_initialized = 0;
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HEIMDAL_MUTEX_lock(&crypto_mutex);
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if (!rng_initialized) {
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if (seed_something())
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krb5_abortx(NULL, "Fatal: could not seed the "
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"random number generator");
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rng_initialized = 1;
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}
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HEIMDAL_MUTEX_unlock(&crypto_mutex);
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if (RAND_bytes(buf, len) <= 0)
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krb5_abortx(NULL, "Failed to generate random block");
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}
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