xdmauth.c

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/* $XConsortium: xdmauth.c,v 1.14 95/07/10 21:18:07 gildea Exp $ */
/*

Copyright (c) 1988  X Consortium

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

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 X CONSORTIUM 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 the X Consortium 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 X Consortium.

*/

/*
 * XDM-AUTHENTICATION-1 (XDMCP authentication) and
 * XDM-AUTHORIZATION-1 (client authorization) protocols
 *
 * Author:  Keith Packard, MIT X Consortium
 */

#include "X.h"
#include "Xtrans.h"
#include "os.h"
#include "osdep.h"
#include "dixstruct.h"

#ifdef HASXDMAUTH

static Bool authFromXDMCP;

#ifdef XDMCP
#include "Xmd.h"
#undef REQUEST
#include "Xdmcp.h"

/* XDM-AUTHENTICATION-1 */

static XdmAuthKeyRec	privateKey;
static char XdmAuthenticationName[] = "XDM-AUTHENTICATION-1";
#define XdmAuthenticationNameLen (sizeof XdmAuthenticationName - 1)
static XdmAuthKeyRec	rho;

static Bool XdmAuthenticationValidator (privateData, incomingData, packet_type)
    ARRAY8Ptr	privateData, incomingData;
    xdmOpCode	packet_type;
{
    XdmAuthKeyPtr	incoming;

    XdmcpUnwrap (incomingData->data, &privateKey,
			      incomingData->data,incomingData->length);
    switch (packet_type)
    {
    case ACCEPT:
    	if (incomingData->length != 8)
	    return FALSE;
    	incoming = (XdmAuthKeyPtr) incomingData->data;
    	XdmcpDecrementKey (incoming);
    	return XdmcpCompareKeys (incoming, &rho);
    }
    return FALSE;
}

static Bool
XdmAuthenticationGenerator (privateData, outgoingData, packet_type)
    ARRAY8Ptr	privateData, outgoingData;
    xdmOpCode	packet_type;
{
    outgoingData->length = 0;
    outgoingData->data = 0;
    switch (packet_type)
    {
    case REQUEST:
	if (XdmcpAllocARRAY8 (outgoingData, 8))
	    XdmcpWrap (&rho, &privateKey, outgoingData->data, 8);
    }
    return TRUE;
}

static Bool
XdmAuthenticationAddAuth (name_len, name, data_len, data)
    int	    name_len, data_len;
    char    *name, *data;
{
    Bool    ret;
    XdmcpUnwrap (data, &privateKey, data, data_len);
    authFromXDMCP = TRUE;
    ret = AddAuthorization (name_len, name, data_len, data);
    authFromXDMCP = FALSE;
    return ret;
}


#define atox(c)	('0' <= c && c <= '9' ? c - '0' : \
		 'a' <= c && c <= 'f' ? c - 'a' + 10 : \
		 'A' <= c && c <= 'F' ? c - 'A' + 10 : -1)

static int
HexToBinary (in, out, len)
    char    *out, *in;
    int len;
{
    int	    top, bottom;

    while (len > 0)
    {
	top = atox(in[0]);
	if (top == -1)
	    return 0;
	bottom = atox(in[1]);
	if (bottom == -1)
	    return 0;
	*out++ = (top << 4) | bottom;
	in += 2;
	len -= 2;
    }
    if (len)
	return 0;
    *out++ = '\0';
    return 1;
}

void
XdmAuthenticationInit (cookie, cookie_len)
    char    *cookie;
    int	    cookie_len;
{
    bzero (privateKey.data, 8);
    if (!strncmp (cookie, "0x", 2) || !strncmp (cookie, "0X", 2))
    {
	if (cookie_len > 2 + 2 * 8)
	    cookie_len = 2 + 2 * 8;
	HexToBinary (cookie + 2, (char *)privateKey.data, cookie_len - 2);
    }
    else
    {
    	if (cookie_len > 7)
	    cookie_len = 7;
    	memmove (privateKey.data + 1, cookie, cookie_len);
    }
    XdmcpGenerateKey (&rho);
    XdmcpRegisterAuthentication (XdmAuthenticationName, XdmAuthenticationNameLen,
				 &rho,
				 sizeof (rho),
				 XdmAuthenticationValidator,
				 XdmAuthenticationGenerator,
				 XdmAuthenticationAddAuth);
}

#endif /* XDMCP */

/* XDM-AUTHORIZATION-1 */
typedef struct _XdmAuthorization {
    struct _XdmAuthorization	*next;
    XdmAuthKeyRec		rho;
    XdmAuthKeyRec		key;
    XID				id;
} XdmAuthorizationRec, *XdmAuthorizationPtr;

static XdmAuthorizationPtr xdmAuth;

typedef struct _XdmClientAuth {
    struct _XdmClientAuth   *next;
    XdmAuthKeyRec	    rho;
    char		    client[6];
    long		    time;
} XdmClientAuthRec, *XdmClientAuthPtr;

static XdmClientAuthPtr    xdmClients;
static long	    clockOffset;
static Bool	    gotClock;

#define TwentyMinutes	(20 * 60)
#define TwentyFiveMinutes (25 * 60)

static Bool
XdmClientAuthCompare (a, b)
    XdmClientAuthPtr	a, b;
{
    int	i;

    if (!XdmcpCompareKeys (&a->rho, &b->rho))
	return FALSE;
    for (i = 0; i < 6; i++)
	if (a->client[i] != b->client[i])
	    return FALSE;
    return a->time == b->time;
}

static void
XdmClientAuthDecode (plain, auth)
    unsigned char	*plain;
    XdmClientAuthPtr	auth;
{
    int	    i, j;

    j = 0;
    for (i = 0; i < 8; i++)
    {
	auth->rho.data[i] = plain[j];
	++j;
    }
    for (i = 0; i < 6; i++)
    {
	auth->client[i] = plain[j];
	++j;
    }
    auth->time = 0;
    for (i = 0; i < 4; i++)
    {
	auth->time |= plain[j] << ((3 - i) << 3);
	j++;
    }
}

static void
XdmClientAuthTimeout (now)
    long	now;
{
    XdmClientAuthPtr	client, next, prev;

    prev = 0;
    for (client = xdmClients; client; client=next)
    {
	next = client->next;
	if (abs (now - client->time) > TwentyFiveMinutes)
	{
	    if (prev)
		prev->next = next;
	    else
		xdmClients = next;
	    xfree (client);
	}
	else
	    prev = client;
    }
}

static XdmClientAuthPtr
XdmAuthorizationValidate (plain, length, rho, xclient, reason)
    unsigned char	*plain;
    int			length;
    XdmAuthKeyPtr	rho;
    ClientPtr		xclient;
    char		**reason;
{
    XdmClientAuthPtr	client, existing;
    long		now;
    int			i;

    if (length != (192 / 8)) {
	if (reason)
	    *reason = "Bad XDM authorization key length";
	return NULL;
    }
    client = (XdmClientAuthPtr) xalloc (sizeof (XdmClientAuthRec));
    if (!client)
	return NULL;
    XdmClientAuthDecode (plain, client);
    if (!XdmcpCompareKeys (&client->rho, rho))
    {
	xfree (client);
	if (reason)
	    *reason = "Invalid XDM-AUTHORIZATION-1 key value";
	return NULL;
    }
    for (i = 18; i < 24; i++)
	if (plain[i] != 0) {
	    xfree (client);
	    if (reason)
		*reason = "Invalid XDM-AUTHORIZATION-1 key value";
	    return NULL;
	}
    if (xclient) {
	int family, addr_len;
	Xtransaddr *addr;

	if (_XSERVTransGetPeerAddr(((OsCommPtr)xclient->osPrivate)->trans_conn,
				   &family, &addr_len, &addr) == 0
	    && _XSERVTransConvertAddress(&family, &addr_len, &addr) == 0) {
#ifdef TCPCONN
	    if (family == FamilyInternet &&
		memcmp((char *)addr, client->client, 4) != 0) {
		xfree (client);
		xfree (addr);
		if (reason)
		    *reason = "Invalid XDM-AUTHORIZATION-1 key value";
		return NULL;

	    }
#endif
	    xfree (addr);
	}
    }
    now = time(0);
    if (!gotClock)
    {
	clockOffset = client->time - now;
	gotClock = TRUE;
    }
    now += clockOffset;
    XdmClientAuthTimeout (now);
    if (abs (client->time - now) > TwentyMinutes)
    {
	xfree (client);
	if (reason)
	    *reason = "Excessive XDM-AUTHORIZATION-1 time offset";
	return NULL;
    }
    for (existing = xdmClients; existing; existing=existing->next)
    {
	if (XdmClientAuthCompare (existing, client))
	{
	    xfree (client);
	    if (reason)
		*reason = "XDM authorization key matches an existing client!";
	    return NULL;
	}
    }
    return client;
}

int
XdmAddCookie (data_length, data, id)
unsigned short	data_length;
char	*data;
XID	id;
{
    XdmAuthorizationPtr	new;
    unsigned char	*rho_bits, *key_bits;

    switch (data_length)
    {
    case 16:		    /* auth from files is 16 bytes long */
	if (authFromXDMCP)
	{
	    /* R5 xdm sent bogus authorization data in the accept packet,
	     * but we can recover */
	    rho_bits = rho.data;
	    key_bits = (unsigned char *) data;
	    key_bits[0] = '\0';
	}
	else
	{
	    rho_bits = (unsigned char *) data;
	    key_bits = (unsigned char *) (data + 8);
	}
	break;
    case 8:		    /* auth from XDMCP is 8 bytes long */
	rho_bits = rho.data;
	key_bits = (unsigned char *) data;
	break;
    default:
	return 0;
    }
    /* the first octet of the key must be zero */
    if (key_bits[0] != '\0')
	return 0;
    new = (XdmAuthorizationPtr) xalloc (sizeof (XdmAuthorizationRec));
    if (!new)
	return 0;
    new->next = xdmAuth;
    xdmAuth = new;
    memmove (new->key.data, key_bits, (int) 8);
    memmove (new->rho.data, rho_bits, (int) 8);
    new->id = id;
    return 1;
}

XID
XdmCheckCookie (cookie_length, cookie, xclient, reason)
    unsigned short	cookie_length;
    char	*cookie;
    ClientPtr xclient;
    char	**reason;
{
    XdmAuthorizationPtr	auth;
    XdmClientAuthPtr	client;
    unsigned char	*plain;

    /* Auth packets must be a multiple of 8 bytes long */
    if (cookie_length & 7)
	return (XID) -1;
    plain = (unsigned char *) xalloc (cookie_length);
    if (!plain)
	return (XID) -1;
    for (auth = xdmAuth; auth; auth=auth->next) {
	XdmcpUnwrap (cookie, &auth->key, plain, cookie_length);
	if (client = XdmAuthorizationValidate (plain, cookie_length, &auth->rho, xclient, reason))
	{
	    client->next = xdmClients;
	    xdmClients = client;
	    xfree (plain);
	    return auth->id;
	}
    }
    xfree (plain);
    return (XID) -1;
}

int
XdmResetCookie ()
{
    XdmAuthorizationPtr	auth, next_auth;
    XdmClientAuthPtr	client, next_client;

    for (auth = xdmAuth; auth; auth=next_auth)
    {
	next_auth = auth->next;
	xfree (auth);
    }
    xdmAuth = 0;
    for (client = xdmClients; client; client=next_client)
    {
	next_client = client->next;
	xfree (client);
    }
    xdmClients = (XdmClientAuthPtr) 0;
    return 1;
}

XID
XdmToID (cookie_length, cookie)
unsigned short	cookie_length;
char	*cookie;
{
    XdmAuthorizationPtr	auth;
    XdmClientAuthPtr	client;
    unsigned char	*plain;

    plain = (unsigned char *) xalloc (cookie_length);
    if (!plain)
	return (XID) -1;
    for (auth = xdmAuth; auth; auth=auth->next) {
	XdmcpUnwrap (cookie, &auth->key, plain, cookie_length);
	if (client = XdmAuthorizationValidate (plain, cookie_length, &auth->rho, NULL, NULL))
	{
	    xfree (client);
	    xfree (cookie);
	    return auth->id;
	}
    }
    xfree (cookie);
    return (XID) -1;
}

int
XdmFromID (id, data_lenp, datap)
XID id;
unsigned short	*data_lenp;
char	**datap;
{
    XdmAuthorizationPtr	auth;

    for (auth = xdmAuth; auth; auth=auth->next) {
	if (id == auth->id) {
	    *data_lenp = 16;
	    *datap = (char *) &auth->rho;
	    return 1;
	}
    }
    return 0;
}

int
XdmRemoveCookie (data_length, data)
unsigned short	data_length;
char	*data;
{
    XdmAuthorizationPtr	auth, prev;
    XdmAuthKeyPtr	key_bits, rho_bits;

    prev = 0;
    switch (data_length)
    {
    case 16:
	rho_bits = (XdmAuthKeyPtr) data;
	key_bits = (XdmAuthKeyPtr) (data + 8);
	break;
    case 8:
	rho_bits = &rho;
	key_bits = (XdmAuthKeyPtr) data;
	break;
    default:
	return 0;
    }
    for (auth = xdmAuth; auth; auth=auth->next) {
	if (XdmcpCompareKeys (rho_bits, &auth->rho) &&
	    XdmcpCompareKeys (key_bits, &auth->key))
 	{
	    if (prev)
		prev->next = auth->next;
	    else
		xdmAuth = auth->next;
	    xfree (auth);
	    return 1;
	}
    }
    return 0;
}

#endif