wmi-1.3.16 from opsview.com
This commit is contained in:
Are Casilla
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/*
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Unix SMB/CIFS implementation.
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Functions to create reasonable random numbers for crypto use.
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Copyright (C) Jeremy Allison 2001
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "includes.h"
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#include "system/filesys.h"
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#include "lib/crypto/crypto.h"
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#include "system/locale.h"
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/**
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* @file
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* @brief Random number generation
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*/
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static unsigned char hash[258];
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static uint32_t counter;
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static BOOL done_reseed = False;
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static void (*reseed_callback)(int *newseed);
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/**
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Copy any user given reseed data.
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**/
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_PUBLIC_ void set_rand_reseed_callback(void (*fn)(int *))
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{
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reseed_callback = fn;
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set_need_random_reseed();
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}
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/**
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* Tell the random number generator it needs to reseed.
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*/
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_PUBLIC_ void set_need_random_reseed(void)
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{
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done_reseed = False;
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}
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static void get_rand_reseed_data(int *reseed_data)
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{
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if (reseed_callback) {
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reseed_callback(reseed_data);
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} else {
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*reseed_data = 0;
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}
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}
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/****************************************************************
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Setup the seed.
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*****************************************************************/
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static void seed_random_stream(unsigned char *seedval, size_t seedlen)
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{
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unsigned char j = 0;
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size_t ind;
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for (ind = 0; ind < 256; ind++)
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hash[ind] = (unsigned char)ind;
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for( ind = 0; ind < 256; ind++) {
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unsigned char tc;
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j += (hash[ind] + seedval[ind%seedlen]);
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tc = hash[ind];
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hash[ind] = hash[j];
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hash[j] = tc;
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}
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hash[256] = 0;
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hash[257] = 0;
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}
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/****************************************************************
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Get datasize bytes worth of random data.
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*****************************************************************/
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static void get_random_stream(unsigned char *data, size_t datasize)
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{
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unsigned char index_i = hash[256];
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unsigned char index_j = hash[257];
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size_t ind;
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for( ind = 0; ind < datasize; ind++) {
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unsigned char tc;
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unsigned char t;
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index_i++;
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index_j += hash[index_i];
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tc = hash[index_i];
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hash[index_i] = hash[index_j];
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hash[index_j] = tc;
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t = hash[index_i] + hash[index_j];
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data[ind] = hash[t];
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}
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hash[256] = index_i;
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hash[257] = index_j;
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}
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/****************************************************************
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Get a 16 byte hash from the contents of a file.
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Note that the hash is initialised, because the extra entropy is not
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worth the valgrind pain.
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*****************************************************************/
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static void do_filehash(const char *fname, unsigned char *the_hash)
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{
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unsigned char buf[1011]; /* deliberate weird size */
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unsigned char tmp_md4[16];
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int fd, n;
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ZERO_STRUCT(tmp_md4);
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fd = open(fname,O_RDONLY,0);
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if (fd == -1)
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return;
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while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
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mdfour(tmp_md4, buf, n);
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for (n=0;n<16;n++)
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the_hash[n] ^= tmp_md4[n];
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}
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close(fd);
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}
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/**************************************************************
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Try and get a good random number seed. Try a number of
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different factors. Firstly, try /dev/urandom - use if exists.
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We use /dev/urandom as a read of /dev/random can block if
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the entropy pool dries up. This leads clients to timeout
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or be very slow on connect.
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If we can't use /dev/urandom then seed the stream random generator
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above...
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**************************************************************/
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static int do_reseed(BOOL use_fd, int fd)
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{
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unsigned char seed_inbuf[40];
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uint32_t v1, v2; struct timeval tval; pid_t mypid;
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int reseed_data = 0;
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if (use_fd) {
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if (fd != -1)
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return fd;
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fd = open( "/dev/urandom", O_RDONLY,0);
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if(fd >= 0)
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return fd;
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}
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/* Add in some secret file contents */
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do_filehash("/etc/shadow", &seed_inbuf[0]);
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/*
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* Add the counter, time of day, and pid.
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*/
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GetTimeOfDay(&tval);
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mypid = getpid();
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v1 = (counter++) + mypid + tval.tv_sec;
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v2 = (counter++) * mypid + tval.tv_usec;
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SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
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SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
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/*
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* Add any user-given reseed data.
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*/
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get_rand_reseed_data(&reseed_data);
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if (reseed_data) {
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size_t i;
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for (i = 0; i < sizeof(seed_inbuf); i++)
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seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
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}
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seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
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return -1;
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}
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/**
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Interface to the (hopefully) good crypto random number generator.
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**/
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_PUBLIC_ void generate_random_buffer(uint8_t *out, int len)
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{
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static int urand_fd = -1;
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unsigned char md4_buf[64];
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unsigned char tmp_buf[16];
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unsigned char *p;
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if(!done_reseed) {
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urand_fd = do_reseed(True, urand_fd);
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done_reseed = True;
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}
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if (urand_fd != -1 && len > 0) {
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if (read(urand_fd, out, len) == len)
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return; /* len bytes of random data read from urandom. */
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/* Read of urand error, drop back to non urand method. */
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close(urand_fd);
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urand_fd = -1;
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do_reseed(False, -1);
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done_reseed = True;
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}
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/*
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* Generate random numbers in chunks of 64 bytes,
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* then md4 them & copy to the output buffer.
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* This way the raw state of the stream is never externally
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* seen.
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*/
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p = out;
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while(len > 0) {
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int copy_len = len > 16 ? 16 : len;
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get_random_stream(md4_buf, sizeof(md4_buf));
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mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
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memcpy(p, tmp_buf, copy_len);
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p += copy_len;
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len -= copy_len;
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}
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}
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/**
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generate a single random uint32_t
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**/
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_PUBLIC_ uint32_t generate_random(void)
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{
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uint8_t v[4];
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generate_random_buffer(v, 4);
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return IVAL(v, 0);
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}
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/**
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very basic password quality checker
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**/
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_PUBLIC_ BOOL check_password_quality(const char *s)
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{
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int has_digit=0, has_capital=0, has_lower=0;
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while (*s) {
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if (isdigit((unsigned char)*s)) {
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has_digit++;
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} else if (isupper((unsigned char)*s)) {
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has_capital++;
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} else if (islower((unsigned char)*s)) {
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has_lower++;
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}
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s++;
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}
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return has_digit && has_lower && has_capital;
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}
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/**
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Use the random number generator to generate a random string.
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**/
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_PUBLIC_ char *generate_random_str_list(TALLOC_CTX *mem_ctx, size_t len, const char *list)
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{
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size_t i;
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size_t list_len = strlen(list);
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char *retstr = talloc_array(mem_ctx, char, len + 1);
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if (!retstr) return NULL;
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generate_random_buffer((uint8_t *)retstr, len);
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for (i = 0; i < len; i++) {
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retstr[i] = list[retstr[i] % list_len];
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}
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retstr[i] = '\0';
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return retstr;
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}
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/**
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* Generate a random text string consisting of the specified length.
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* The returned string will be allocated.
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*
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* Characters used are: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,
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*/
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_PUBLIC_ char *generate_random_str(TALLOC_CTX *mem_ctx, size_t len)
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{
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char *retstr;
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const char *c_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
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again:
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retstr = generate_random_str_list(mem_ctx, len, c_list);
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if (!retstr) return NULL;
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/* we need to make sure the random string passes basic quality tests
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or it might be rejected by windows as a password */
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if (len >= 7 && !check_password_quality(retstr)) {
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talloc_free(retstr);
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goto again;
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}
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return retstr;
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}
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