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author | Andrew Tridgell <tridge@samba.org> | 2003-08-13 01:53:07 +0000 |
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committer | Andrew Tridgell <tridge@samba.org> | 2003-08-13 01:53:07 +0000 |
commit | cc3a6ea9920f30925a678c566b4af417da6d455b (patch) | |
tree | 60015a1a5f4b47ac3d133bdbbe32b75815595d4d /source4/lib/genrand.c | |
parent | 4d1f9d1def5bf5fea64722626028d94da49c654c (diff) | |
parent | ef2e26c91b80556af033d3335e55f5dfa6fff31d (diff) | |
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This commit was generated by cvs2svn to compensate for changes in r30,
which included commits to RCS files with non-trunk default branches.
(This used to be commit 3a69cffb062d4f1238b8cae10481c1f2ea4d3d8b)
Diffstat (limited to 'source4/lib/genrand.c')
-rw-r--r-- | source4/lib/genrand.c | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/source4/lib/genrand.c b/source4/lib/genrand.c new file mode 100644 index 0000000000..e2e66f7e58 --- /dev/null +++ b/source4/lib/genrand.c @@ -0,0 +1,267 @@ +/* + Unix SMB/CIFS implementation. + + Functions to create reasonable random numbers for crypto use. + + Copyright (C) Jeremy Allison 2001 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +#include "includes.h" + +static unsigned char hash[258]; +static uint32 counter; +static unsigned char *reseed_data; +static size_t reseed_data_size; + +/**************************************************************** + Copy any user given reseed data. +*****************************************************************/ + +void set_rand_reseed_data(unsigned char *data, size_t len) +{ + SAFE_FREE(reseed_data); + reseed_data_size = 0; + + reseed_data = (unsigned char *)memdup(data, len); + if (reseed_data) + reseed_data_size = len; +} + +/**************************************************************** + Setup the seed. +*****************************************************************/ + +static void seed_random_stream(unsigned char *seedval, size_t seedlen) +{ + unsigned char j = 0; + size_t ind; + + for (ind = 0; ind < 256; ind++) + hash[ind] = (unsigned char)ind; + + for( ind = 0; ind < 256; ind++) { + unsigned char tc; + + j += (hash[ind] + seedval[ind%seedlen]); + + tc = hash[ind]; + hash[ind] = hash[j]; + hash[j] = tc; + } + + hash[256] = 0; + hash[257] = 0; +} + +/**************************************************************** + Get datasize bytes worth of random data. +*****************************************************************/ + +static void get_random_stream(unsigned char *data, size_t datasize) +{ + unsigned char index_i = hash[256]; + unsigned char index_j = hash[257]; + size_t ind; + + for( ind = 0; ind < datasize; ind++) { + unsigned char tc; + unsigned char t; + + index_i++; + index_j += hash[index_i]; + + tc = hash[index_i]; + hash[index_i] = hash[index_j]; + hash[index_j] = tc; + + t = hash[index_i] + hash[index_j]; + data[ind] = hash[t]; + } + + hash[256] = index_i; + hash[257] = index_j; +} + +/**************************************************************** + Get a 16 byte hash from the contents of a file. + Note that the hash is not initialised. +*****************************************************************/ + +static void do_filehash(const char *fname, unsigned char *the_hash) +{ + unsigned char buf[1011]; /* deliberate weird size */ + unsigned char tmp_md4[16]; + int fd, n; + + fd = sys_open(fname,O_RDONLY,0); + if (fd == -1) + return; + + while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) { + mdfour(tmp_md4, buf, n); + for (n=0;n<16;n++) + the_hash[n] ^= tmp_md4[n]; + } + close(fd); +} + +/************************************************************** + Try and get a good random number seed. Try a number of + different factors. Firstly, try /dev/urandom - use if exists. + + We use /dev/urandom as a read of /dev/random can block if + the entropy pool dries up. This leads clients to timeout + or be very slow on connect. + + If we can't use /dev/urandom then seed the stream random generator + above... +**************************************************************/ + +static int do_reseed(BOOL use_fd, int fd) +{ + unsigned char seed_inbuf[40]; + uint32 v1, v2; struct timeval tval; pid_t mypid; + struct passwd *pw; + + if (use_fd) { + if (fd != -1) + return fd; + + fd = sys_open( "/dev/urandom", O_RDONLY,0); + if(fd >= 0) + return fd; + } + + /* Add in some secret file contents */ + + do_filehash("/etc/shadow", &seed_inbuf[0]); + do_filehash(lp_smb_passwd_file(), &seed_inbuf[16]); + + /* + * Add in the root encrypted password. + * On any system where security is taken + * seriously this will be secret. + */ + + pw = getpwnam_alloc("root"); + if (pw && pw->pw_passwd) { + size_t i; + unsigned char md4_tmp[16]; + mdfour(md4_tmp, (unsigned char *)pw->pw_passwd, strlen(pw->pw_passwd)); + for (i=0;i<16;i++) + seed_inbuf[8+i] ^= md4_tmp[i]; + passwd_free(&pw); + } + + /* + * Add the counter, time of day, and pid. + */ + + GetTimeOfDay(&tval); + mypid = getpid(); + v1 = (counter++) + mypid + tval.tv_sec; + v2 = (counter++) * mypid + tval.tv_usec; + + SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32)); + SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36)); + + /* + * Add any user-given reseed data. + */ + + if (reseed_data) { + size_t i; + for (i = 0; i < sizeof(seed_inbuf); i++) + seed_inbuf[i] ^= reseed_data[i % reseed_data_size]; + } + + seed_random_stream(seed_inbuf, sizeof(seed_inbuf)); + + return -1; +} + +/******************************************************************* + Interface to the (hopefully) good crypto random number generator. +********************************************************************/ + +void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now) +{ + static BOOL done_reseed = False; + static int urand_fd = -1; + unsigned char md4_buf[64]; + unsigned char tmp_buf[16]; + unsigned char *p; + + if(!done_reseed || do_reseed_now) { + urand_fd = do_reseed(True, urand_fd); + done_reseed = True; + } + + if (urand_fd != -1 && len > 0) { + + if (read(urand_fd, out, len) == len) + return; /* len bytes of random data read from urandom. */ + + /* Read of urand error, drop back to non urand method. */ + close(urand_fd); + urand_fd = -1; + do_reseed(False, -1); + done_reseed = True; + } + + /* + * Generate random numbers in chunks of 64 bytes, + * then md4 them & copy to the output buffer. + * This way the raw state of the stream is never externally + * seen. + */ + + p = out; + while(len > 0) { + int copy_len = len > 16 ? 16 : len; + + get_random_stream(md4_buf, sizeof(md4_buf)); + mdfour(tmp_buf, md4_buf, sizeof(md4_buf)); + memcpy(p, tmp_buf, copy_len); + p += copy_len; + len -= copy_len; + } +} + +/******************************************************************* + Use the random number generator to generate a random string. +********************************************************************/ + +static char c_list[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,"; + +char *generate_random_str(size_t len) +{ + static unsigned char retstr[256]; + size_t i; + + memset(retstr, '\0', sizeof(retstr)); + + if (len > sizeof(retstr)-1) + len = sizeof(retstr) -1; + generate_random_buffer( retstr, len, False); + for (i = 0; i < len; i++) + retstr[i] = c_list[ retstr[i] % (sizeof(c_list)-1) ]; + + retstr[i] = '\0'; + + return (char *)retstr; +} |