diff options
Diffstat (limited to 'source3/lib')
| -rw-r--r-- | source3/lib/genrand.c | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/source3/lib/genrand.c b/source3/lib/genrand.c index 8d7084d9f6..e20f054504 100644 --- a/source3/lib/genrand.c +++ b/source3/lib/genrand.c @@ -26,7 +26,6 @@ extern int DEBUGLEVEL; static uint32 counter = 0; - /**************************************************************** get a 16 byte hash from the contents of a file Note that the hash is not initialised. @@ -102,18 +101,19 @@ static void do_dirrand(char *name, unsigned char *buf, int buf_len) Try and get a good random number seed. Try a number of different factors. Firstly, try /dev/random and try and read from this. If this fails iterate through /tmp and - XOR all the file timestamps. If this fails then just use - a combination of pid and time of day (yes I know this + /dev and XOR all the file timestamps. Next add in + a hash of the contents of /etc/shadow and the smb passwd + file and a combination of pid and time of day (yes I know this sucks :-). Finally md4 the result. The result goes in a 16 byte buffer passed from the caller **************************************************************/ -static void do_reseed(unsigned char *md4_outbuf) +static uint32 do_reseed(unsigned char *md4_outbuf) { unsigned char md4_inbuf[40]; BOOL got_random = False; - uint32 v1, v2; + uint32 v1, v2, ret; int fd; struct timeval tval; pid_t mypid; @@ -135,7 +135,7 @@ static void do_reseed(unsigned char *md4_outbuf) if(!got_random) { /* - * /dev/random failed - try /tmp/ for timestamps. + * /dev/random failed - try /tmp and /dev for timestamps. */ do_dirrand("/tmp", md4_inbuf, sizeof(md4_inbuf)); do_dirrand("/dev", md4_inbuf, sizeof(md4_inbuf)); @@ -148,7 +148,7 @@ static void do_reseed(unsigned char *md4_outbuf) /* add in the root encrypted password. On any system where security is taken seriously this will be secret */ pw = getpwnam("root"); - if (pw) { + if (pw && pw->pw_passwd) { int i; unsigned char md4_tmp[16]; mdfour(md4_tmp, pw->pw_passwd, strlen(pw->pw_passwd)); @@ -168,6 +168,16 @@ static void do_reseed(unsigned char *md4_outbuf) SIVAL(md4_inbuf, 36, v2 ^ IVAL(md4_inbuf, 36)); mdfour(md4_outbuf, md4_inbuf, sizeof(md4_inbuf)); + + /* + * Return a 32 bit int created from XORing the + * 16 bit return buffer. + */ + + ret = IVAL(md4_outbuf, 0); + ret ^= IVAL(md4_outbuf, 4); + ret ^= IVAL(md4_outbuf, 8); + return (ret ^ IVAL(md4_outbuf, 12)); } /******************************************************************* @@ -177,25 +187,38 @@ static void do_reseed(unsigned char *md4_outbuf) void generate_random_buffer( unsigned char *out, int len, BOOL re_seed) { static BOOL done_reseed = False; + static unsigned char md4_buf[16]; unsigned char tmp_buf[16]; - unsigned char md4_buf[16]; unsigned char *p; if(!done_reseed || re_seed) { - do_reseed(md4_buf); + srandom(do_reseed(md4_buf)); done_reseed = True; } /* * Generate random numbers in chunks of 64 bytes, * then md4 them & copy to the output buffer. + * Added XOR with output from random, seeded + * by the original md4_buf. This is to stop the + * output from this function being the previous + * md4_buf md4'ed. The output from this function + * is often output onto the wire, and so it should + * not be possible to guess the next output from + * this function based on the previous output. + * XORing in the output from random(), seeded by + * the original md4 hash should stop this. JRA. */ p = out; while(len > 0) { + int i; int copy_len = len > 16 ? 16 : len; mdfour(tmp_buf, md4_buf, sizeof(md4_buf)); memcpy(md4_buf, tmp_buf, sizeof(md4_buf)); + /* XOR in output from random(). */ + for(i = 0; i < 4; i++) + SIVAL(tmp_buf, i*4, (IVAL(tmp_buf, i*4) ^ (uint32)random())); memcpy(p, tmp_buf, copy_len); p += copy_len; len -= copy_len; |