path: root/tdm/backend/genauth.c

/*

Copyright 1988, 1998  The Open Group
Copyright 2003-2004 Oswald Buddenhagen <ossi@kde.org>

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of a copyright holder shall
not be used in advertising or otherwise to promote the sale, use or
other dealings in this Software without prior written authorization
from the copyright holder.

*/

/*
 * xdm - display manager daemon
 * Author: Keith Packard, MIT X Consortium
 */

#include "dm.h"
#include "dm_auth.h"
#include "dm_error.h"

#ifdef NEED_ENTROPY

# include <signal.h>

/* ####################################################################### */

/*
 * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
 * Copyright (c) 2001-2002 Damien Miller.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "dm_socket.h"

#include <string.h>

#ifndef INADDR_LOOPBACK
# define INADDR_LOOPBACK 0x7F000001U
#endif

#ifndef offsetof
# define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif

static int
getPrngdBytes( char *buf, int len,
               unsigned short tcp_port, const char *socket_path )
{
		int fd, addr_len, rval, errors;
		char msg[2];
		struct sockaddr *addr;
		struct sockaddr_in addr_in;
		struct sockaddr_un addr_un;
		int af;
		SIGFUNC old_sigpipe;

		if (tcp_port) {
				memset( &addr_in, 0, sizeof(addr_in) );
				af = addr_in.sin_family = AF_INET;
				addr_in.sin_addr.s_addr = htonl( INADDR_LOOPBACK );
				addr_in.sin_port = htons( tcp_port );
				addr_len = sizeof(addr_in);
				addr = (struct sockaddr *)&addr_in;
		} else if (*socket_path) {
				unsigned spl = strlen( socket_path );
				if (spl >= sizeof(addr_un.sun_path)) {
						LogError( "get_random_prngd: "
						          "Random pool path is too long\n" );
						return -1;
				}
				af = addr_un.sun_family = AF_UNIX;
				strncpy( addr_un.sun_path, socket_path,
				         sizeof(addr_un.sun_path) );
				addr_len = offsetof( struct sockaddr_un, sun_path ) + spl + 1;
				addr = (struct sockaddr *)&addr_un;
		} else
				return -1;

		old_sigpipe = Signal( SIGPIPE, SIG_IGN );

		errors = 0;
		rval = -1;
reopen:
		if ((fd = socket( af, SOCK_STREAM, 0 )) < 0) {
				LogError( "Couldn't create socket: %m\n" );
				goto done;
		}

		if (connect( fd, (struct sockaddr *)addr, addr_len )) {
				if (af == AF_INET)
						LogError( "Couldn't connect to PRNGD port %d: %m\n",
						          tcp_port );
				else
						LogError( "Couldn't connect to PRNGD socket %\"s: %m\n",
						          socket_path );
				goto done;
		}

		/* Send blocking read request to PRNGD */
		msg[0] = 0x02;
		msg[1] = len;

		if (Writer( fd, msg, sizeof(msg) ) != sizeof(msg)) {
				if (errno == EPIPE && errors < 10) {
						close( fd );
						errors++;
						goto reopen;
				}
				LogError( "Couldn't write to PRNGD socket: %m\n" );
				goto done;
		}

		if (Reader( fd, buf, len ) != len) {
				if (errno == EPIPE && errors < 10) {
						close( fd );
						errors++;
						goto reopen;
				}
				LogError( "Couldn't read from PRNGD socket: %m\n" );
				goto done;
		}

		rval = 0;
done:
		Signal( SIGPIPE, old_sigpipe );
		if (fd != -1)
				close( fd );
		return rval;
}

/* ####################################################################### */

/*
 * Stolen from the Linux kernel.
 *
 * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999.	 All
 * rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, and the entire permission notice in its entirety,
 *    including the disclaimer of warranties.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

static unsigned epool[32], erotate, eadd_ptr;

static void
add_entropy( unsigned const *in, int nwords )
{
		static unsigned const twist_table[8] = {
				         0, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
				0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
		unsigned i, w;
		int new_rotate;

		while (nwords--) {
				w = *in++;
				w = (w<<erotate | w>>(32-erotate)) & 0xffffffff;
				i = eadd_ptr = (eadd_ptr - 1) & 31;
				new_rotate = erotate + 14;
				if (i)
						new_rotate = erotate + 7;
				erotate = new_rotate & 31;
				w ^= epool[(i + 26) & 31];
				w ^= epool[(i + 20) & 31];
				w ^= epool[(i + 14) & 31];
				w ^= epool[(i + 7) & 31];
				w ^= epool[(i + 1) & 31];
				w ^= epool[i];
				epool[i] = (w >> 3) ^ twist_table[w & 7];
		}
}

/* ####################################################################### */

/*
 * This code implements something close to the MD5 message-digest
 * algorithm. This code is based on code written by Colin Plumb
 * in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 */

/* The four core functions - F1 is optimized somewhat */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1 (z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define pmd5_step(f, w, x, y, z, data, s) \
		(w += (f(x, y, z) + data) & 0xffffffff, w = w<<s | w>>(32-s), w += x)

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.
 */
static void
pmd5_hash( unsigned *out, unsigned const in[16] )
{
	unsigned a, b, c, d;

	a = out[0];
	b = out[1];
	c = out[2];
	d = out[3];

	pmd5_step( F1, a, b, c, d, in[0] + 0xd76aa478, 7 );
	pmd5_step( F1, d, a, b, c, in[1] + 0xe8c7b756, 12 );
	pmd5_step( F1, c, d, a, b, in[2] + 0x242070db, 17 );
	pmd5_step( F1, b, c, d, a, in[3] + 0xc1bdceee, 22 );
	pmd5_step( F1, a, b, c, d, in[4] + 0xf57c0faf, 7 );
	pmd5_step( F1, d, a, b, c, in[5] + 0x4787c62a, 12 );
	pmd5_step( F1, c, d, a, b, in[6] + 0xa8304613, 17 );
	pmd5_step( F1, b, c, d, a, in[7] + 0xfd469501, 22 );
	pmd5_step( F1, a, b, c, d, in[8] + 0x698098d8, 7 );
	pmd5_step( F1, d, a, b, c, in[9] + 0x8b44f7af, 12 );
	pmd5_step( F1, c, d, a, b, in[10] + 0xffff5bb1, 17 );
	pmd5_step( F1, b, c, d, a, in[11] + 0x895cd7be, 22 );
	pmd5_step( F1, a, b, c, d, in[12] + 0x6b901122, 7 );
	pmd5_step( F1, d, a, b, c, in[13] + 0xfd987193, 12 );
	pmd5_step( F1, c, d, a, b, in[14] + 0xa679438e, 17 );
	pmd5_step( F1, b, c, d, a, in[15] + 0x49b40821, 22 );

	pmd5_step( F2, a, b, c, d, in[1] + 0xf61e2562, 5 );
	pmd5_step( F2, d, a, b, c, in[6] + 0xc040b340, 9 );
	pmd5_step( F2, c, d, a, b, in[11] + 0x265e5a51, 14 );
	pmd5_step( F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20 );
	pmd5_step( F2, a, b, c, d, in[5] + 0xd62f105d, 5 );
	pmd5_step( F2, d, a, b, c, in[10] + 0x02441453, 9 );
	pmd5_step( F2, c, d, a, b, in[15] + 0xd8a1e681, 14 );
	pmd5_step( F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20 );
	pmd5_step( F2, a, b, c, d, in[9] + 0x21e1cde6, 5 );
	pmd5_step( F2, d, a, b, c, in[14] + 0xc33707d6, 9 );
	pmd5_step( F2, c, d, a, b, in[3] + 0xf4d50d87, 14 );
	pmd5_step( F2, b, c, d, a, in[8] + 0x455a14ed, 20 );
	pmd5_step( F2, a, b, c, d, in[13] + 0xa9e3e905, 5 );
	pmd5_step( F2, d, a, b, c, in[2] + 0xfcefa3f8, 9 );
	pmd5_step( F2, c, d, a, b, in[7] + 0x676f02d9, 14 );
	pmd5_step( F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20 );

	pmd5_step( F3, a, b, c, d, in[5] + 0xfffa3942, 4 );
	pmd5_step( F3, d, a, b, c, in[8] + 0x8771f681, 11 );
	pmd5_step( F3, c, d, a, b, in[11] + 0x6d9d6122, 16 );
	pmd5_step( F3, b, c, d, a, in[14] + 0xfde5380c, 23 );
	pmd5_step( F3, a, b, c, d, in[1] + 0xa4beea44, 4 );
	pmd5_step( F3, d, a, b, c, in[4] + 0x4bdecfa9, 11 );
	pmd5_step( F3, c, d, a, b, in[7] + 0xf6bb4b60, 16 );
	pmd5_step( F3, b, c, d, a, in[10] + 0xbebfbc70, 23 );
	pmd5_step( F3, a, b, c, d, in[13] + 0x289b7ec6, 4 );
	pmd5_step( F3, d, a, b, c, in[0] + 0xeaa127fa, 11 );
	pmd5_step( F3, c, d, a, b, in[3] + 0xd4ef3085, 16 );
	pmd5_step( F3, b, c, d, a, in[6] + 0x04881d05, 23 );
	pmd5_step( F3, a, b, c, d, in[9] + 0xd9d4d039, 4 );
	pmd5_step( F3, d, a, b, c, in[12] + 0xe6db99e5, 11 );
	pmd5_step( F3, c, d, a, b, in[15] + 0x1fa27cf8, 16 );
	pmd5_step( F3, b, c, d, a, in[2] + 0xc4ac5665, 23 );

	pmd5_step( F4, a, b, c, d, in[0] + 0xf4292244, 6 );
	pmd5_step( F4, d, a, b, c, in[7] + 0x432aff97, 10 );
	pmd5_step( F4, c, d, a, b, in[14] + 0xab9423a7, 15 );
	pmd5_step( F4, b, c, d, a, in[5] + 0xfc93a039, 21 );
	pmd5_step( F4, a, b, c, d, in[12] + 0x655b59c3, 6 );
	pmd5_step( F4, d, a, b, c, in[3] + 0x8f0ccc92, 10 );
	pmd5_step( F4, c, d, a, b, in[10] + 0xffeff47d, 15 );
	pmd5_step( F4, b, c, d, a, in[1] + 0x85845dd1, 21 );
	pmd5_step( F4, a, b, c, d, in[8] + 0x6fa87e4f, 6 );
	pmd5_step( F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10 );
	pmd5_step( F4, c, d, a, b, in[6] + 0xa3014314, 15 );
	pmd5_step( F4, b, c, d, a, in[13] + 0x4e0811a1, 21 );
	pmd5_step( F4, a, b, c, d, in[4] + 0xf7537e82, 6 );
	pmd5_step( F4, d, a, b, c, in[11] + 0xbd3af235, 10 );
	pmd5_step( F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15 );
	pmd5_step( F4, b, c, d, a, in[9] + 0xeb86d391, 21 );

	out[0] += a;
	out[1] += b;
	out[2] += c;
	out[3] += d;
}

/* ####################################################################### */


static int
sumFile( const char *name, int len, int whence, long offset )
{
	int fd, i, cnt, readlen = 0;
	unsigned char buf[0x1000];

	if ((fd = open( name, O_RDONLY )) < 0) {
		Debug( "cannot open entropy source %\"s: %m\n", name );
		return -1;
	}
	lseek( fd, offset, whence );
	while (readlen < len) {
		if (!(cnt = read( fd, buf, sizeof(buf) )))
			break;
		if (cnt < 0) {
			close( fd );
			Debug( "cannot read entropy source %\"s: %m\n", name );
			return -1;
		}
		readlen += cnt;
		if (sizeof(unsigned) == 4)
			add_entropy( (unsigned *)buf, (cnt + 3) / 4 );
		else {
			unsigned buf2[sizeof(buf) / 4];
			for (i = 0; i < cnt; i += 8) {
				buf2[i / 4] = *(unsigned *)(buf + i) & 0xffffffff;
				buf2[i / 4 + 1] = *(unsigned *)(buf + i) >> 32;
			}
			add_entropy( buf2, (cnt + 3) / 4 );
		}
	}
	close( fd );
	Debug( "read %d bytes from entropy source %\"s\n", readlen, name );
	return readlen;
}

void
AddTimerEntropy( void )
{
	struct timeval now;
	gettimeofday( &now, 0 );
	add_entropy( (unsigned *)&now, sizeof(now)/sizeof(unsigned) );
}

#define BSIZ 0x10000

void
AddOtherEntropy( void )
{
	AddTimerEntropy();
	/* XXX -- setup-specific ... use some common ones */
	sumFile( "/var/log/messages", 0x1000, SEEK_END, -0x1000 );
	sumFile( "/var/log/syslog", 0x1000, SEEK_END, -0x1000 );
	sumFile( "/var/log/debug", 0x1000, SEEK_END, -0x1000 );
	sumFile( "/var/log/kern.log", 0x1000, SEEK_END, -0x1000 );
	sumFile( "/var/log/daemon.log", 0x1000, SEEK_END, -0x1000 );
/* root hardly ever has an own box ... maybe pick a random mailbox instead? eek ...
	sumFile( "/var/spool/mail/root", 0x1000, SEEK_END, -0x1000 );
*/
}

void
AddPreGetEntropy( void )
{
	static long offset;
	int readlen;

	AddTimerEntropy();
	if ((readlen = sumFile( randomFile, BSIZ, SEEK_SET, offset )) == BSIZ) {
		offset += readlen;
#if defined(__i386__) || defined(amiga)
		if (!strcmp( randomFile, "/dev/mem" )) {
			if (offset == 0xa0000) /* skip 640kB-1MB ROM mappings */
				offset = 0x100000;
			else if (offset == 0xf00000) /* skip 15-16MB memory hole */
				offset = 0x1000000;
		}
#endif
		return;
	} else if (readlen >= 0 && offset) {
		if ((offset = sumFile( randomFile, BSIZ, SEEK_SET, 0 )) == BSIZ)
			return;
	}
	LogError( "Cannot read randomFile %\"s; "
	          "X cookies may be easily guessable\n", randomFile );
}
#endif

/* ONLY 8 or 16 bytes! */
/* auth MUST be sizeof(unsigned)-aligned! */
int
GenerateAuthData( char *auth, int len )
{
#ifdef HAVE_ARC4RANDOM
	int i;
	unsigned *rnd = (unsigned *)auth;
	if (sizeof(unsigned) == 4)
		for (i = 0; i < len; i += 4)
			rnd[i / 4] = arc4random();
	else
		for (i = 0; i < len; i += 8)
			rnd[i / 8] = arc4random() | (arc4random() << 32);
	return 1;
#else
	int fd;
	const char *rd = randomDevice;
# ifdef DEV_RANDOM
	if (!*rd)
		rd = DEV_RANDOM;
# else
	if (*rd) {
# endif
		if ((fd = open( rd, O_RDONLY )) >= 0) {
			if (read( fd, auth, len ) == len) {
				close( fd );
				return 1;
			}
			close( fd );
			LogError( "Cannot read randomDevice %\"s: %m\n", rd );
		} else
			LogError( "Cannot open randomDevice %\"s: %m\n", rd );
# ifdef DEV_RANDOM
		return 0;
# else
	}

	if (!getPrngdBytes( auth, len, prngdPort, prngdSocket ))
		return 1;

	{
		unsigned *rnd = (unsigned *)auth;
		unsigned tmp[4] = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 };
		AddPreGetEntropy();
		pmd5_hash( tmp, epool );
		add_entropy( tmp, 1 );
		pmd5_hash( tmp, epool + 16 );
		add_entropy( tmp + 2, 1 );
		if (sizeof(unsigned) == 4)
			memcpy( auth, tmp, len );
		else {
			int i;
			for (i = 0; i < len; i += 8)
				rnd[i / 8] = tmp[i / 4] | (tmp[i / 4 + 1] << 32);
		}
	}
	return 1;
# endif
#endif
}

#ifndef HAVE_ARC4RANDOM
int
secureRandom( void )
{
	int rslt;
	GenerateAuthData( (char *)&rslt, sizeof(int) );
	return rslt & 0x7fffffff;
}
#endif