Fix for random stream generator.

Jeremy.
(This used to be commit b2867ddfa26ffbc94d022d88b849ef58fd1cc788)

1 files changed, 186 insertions, 168 deletions

diff --git a/source3/lib/genrand.c b/source3/lib/genrand.c
index 4a7de802e8..86b3b56696 100644
--- a/source3/lib/genrand.c
+++ b/source3/lib/genrand.c
@@ -1,10 +1,10 @@
 /* 
    Unix SMB/Netbios implementation.
-   Version 1.9.
+   Version 2.2
 
    Functions to create reasonable random numbers for crypto use.
 
-   Copyright (C) Jeremy Allison 1998
+   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
@@ -24,12 +24,88 @@
 #include "includes.h"
 
 extern int DEBUGLEVEL;
-static uint32 counter = 0;
+
+
+static unsigned char hash[258];
+static uint32 counter;
+unsigned char *reseed_data;
+size_t reseed_data_size;
+
+/**************************************************************** 
+ Copy any user given reseed data.
+*****************************************************************/
+
+void set_rand_reseed_data(unsigned char *data, size_t len)
+{
+	if (reseed_data)
+		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.
+ Get a 16 byte hash from the contents of a file.
+ Note that the hash is not initialised.
 *****************************************************************/
+
 static void do_filehash(char *fname, unsigned char *hash)
 {
 	unsigned char buf[1011]; /* deliberate weird size */
@@ -37,7 +113,8 @@ static void do_filehash(char *fname, unsigned char *hash)
 	int fd, n;
 
 	fd = sys_open(fname,O_RDONLY,0);
-	if (fd == -1) return;
+	if (fd == -1)
+		return;
 
 	while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
 		mdfour(tmp_md4, buf, n);
@@ -47,185 +124,126 @@ static void do_filehash(char *fname, unsigned char *hash)
 	close(fd);
 }
 
-
-
-/****************************************************************
- Try and get a seed by looking at the atimes of files in a given
- directory. XOR them into the buf array.
-*****************************************************************/
-
-static void do_dirrand(char *name, unsigned char *buf, int buf_len)
-{
-  DIR *dp = opendir(name);
-  pstring fullname;
-  int len_left;
-  int fullname_len;
-  char *pos;
-
-  pstrcpy(fullname, name);
-  fullname_len = strlen(fullname);
-
-  if(fullname_len + 2 > sizeof(pstring))
-    return;
-
-  if(fullname[fullname_len] != '/') {
-    fullname[fullname_len] = '/';
-    fullname[fullname_len+1] = '\0';
-    fullname_len = strlen(fullname);
-  }
-
-  len_left = sizeof(pstring) - fullname_len - 1;
-  pos = &fullname[fullname_len];
-
-  if(dp != NULL) {
-    char *p;
-
-    while ((p = readdirname(dp))) {           
-      SMB_STRUCT_STAT st;
-
-      if(strlen(p) <= len_left)
-        pstrcpy(pos, p);
-
-      if(sys_stat(fullname,&st) == 0) {
-        SIVAL(buf, ((counter * 4)%(buf_len-4)), 
-              IVAL(buf,((counter * 4)%(buf_len-4))) ^ st.st_atime);
-        counter++;
-        DEBUG(10,("do_dirrand: value from file %s.\n", fullname));
-      }
-    }
-    closedir(dp); 
-  }
-}
-
 /**************************************************************
  Try and get a good random number seed. Try a number of
- different factors. Firstly, try /dev/urandom and try and
- read from this. If this fails iterate through /tmp and
- /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.
+ 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.
 
- The result goes in a 16 byte buffer passed from the caller
+ If we can't use /dev/urandom then seed the stream random generator
+ above...
 **************************************************************/
 
-static uint32 do_reseed(unsigned char *md4_outbuf)
+static int do_reseed(BOOL use_fd, int fd)
 {
-  unsigned char md4_inbuf[40];
-  BOOL got_random = False;
-  uint32 v1, v2, ret;
-  int fd;
-  struct timeval tval;
-  pid_t mypid;
-  struct passwd *pw;
-
-  memset(md4_inbuf, '\0', sizeof(md4_inbuf));
-
-  fd = sys_open( "/dev/urandom", O_RDONLY,0);
-  if(fd >= 0) {
-    /* 
-     * We can use /dev/urandom !
-     */
-    if(read(fd, md4_inbuf, 40) == 40) {
-      got_random = True;
-      DEBUG(10,("do_reseed: got 40 bytes from /dev/urandom.\n"));
-    }
-    close(fd);
-  }
-
-  if(!got_random) {
-    /*
-     * /dev/urandom failed - try /dev for timestamps.
-     */
-    do_dirrand("/dev", md4_inbuf, sizeof(md4_inbuf));
-  }
-
-  /* possibly add in some secret file contents */
-  do_filehash("/etc/shadow", &md4_inbuf[0]);
-  do_filehash(lp_smb_passwd_file(), &md4_inbuf[16]);
-
-  /* add in the root encrypted password. On any system where security is taken
-     seriously this will be secret */
-  pw = sys_getpwnam("root");
-  if (pw && pw->pw_passwd) {
-	  int i;
-	  unsigned char md4_tmp[16];
-	  mdfour(md4_tmp, (unsigned char *)pw->pw_passwd, strlen(pw->pw_passwd));
-	  for (i=0;i<16;i++)
-		  md4_inbuf[8+i] ^= md4_tmp[i];
-  }
-
-  /*
-   * Finally add the counter, time of day, and pid.
-   */
-  GetTimeOfDay(&tval);
-  mypid = sys_getpid();
-  v1 = (counter++) + mypid + tval.tv_sec;
-  v2 = (counter++) * mypid + tval.tv_usec;
-
-  SIVAL(md4_inbuf, 32, v1 ^ IVAL(md4_inbuf, 32));
-  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));
+	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 = sys_getpwnam("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];
+	}
+
+	/*
+	 * Add the counter, time of day, and pid.
+	 */
+
+	GetTimeOfDay(&tval);
+	mypid = sys_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 re_seed)
+void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now)
 {
-  static BOOL done_reseed = False;
-  static unsigned char md4_buf[16];
-  unsigned char tmp_buf[16];
-  unsigned char *p;
-
-  if(!done_reseed || re_seed) {
-	  sys_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)sys_random()));
-    memcpy(p, tmp_buf, copy_len);
-    p += copy_len;
-    len -= copy_len;
-  }
+	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;
+	}
 }
 
 /*******************************************************************