xcb_auth.c revision 602e473d 
1/* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a
4 * copy of this software and associated documentation files (the "Software"),
5 * to deal in the Software without restriction, including without limitation
6 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
7 * and/or sell copies of the Software, and to permit persons to whom the
8 * Software is furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
17 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
18 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
19 *
20 * Except as contained in this notice, the names of the authors or their
21 * institutions shall not be used in advertising or otherwise to promote the
22 * sale, use or other dealings in this Software without prior written
23 * authorization from the authors.
24 */
25
26/* Authorization systems for the X protocol. */
27
28#include <assert.h>
29#include <X11/Xauth.h>
30#include <sys/socket.h>
31#include <netinet/in.h>
32#include <sys/un.h>
33#include <sys/param.h>
34#include <unistd.h>
35#include <stdlib.h>
36
37#include "xcb.h"
38#include "xcbint.h"
39
40#ifdef HASXDMAUTH
41#include <X11/Xdmcp.h>
42#endif
43
44enum auth_protos {
45#ifdef HASXDMAUTH
46    AUTH_XA1,
47#endif
48    AUTH_MC1,
49    N_AUTH_PROTOS
50};
51
52#define AUTH_PROTO_XDM_AUTHORIZATION "XDM-AUTHORIZATION-1"
53#define AUTH_PROTO_MIT_MAGIC_COOKIE "MIT-MAGIC-COOKIE-1"
54
55static char *authnames[N_AUTH_PROTOS] = {
56#ifdef HASXDMAUTH
57    AUTH_PROTO_XDM_AUTHORIZATION,
58#endif
59    AUTH_PROTO_MIT_MAGIC_COOKIE,
60};
61
62static int authnameslen[N_AUTH_PROTOS] = {
63#ifdef HASXDMAUTH
64    sizeof(AUTH_PROTO_XDM_AUTHORIZATION) - 1,
65#endif
66    sizeof(AUTH_PROTO_MIT_MAGIC_COOKIE) - 1,
67};
68
69static size_t memdup(char **dst, void *src, size_t len)
70{
71    if(len)
72	*dst = malloc(len);
73    else
74	*dst = 0;
75    if(!*dst)
76	return 0;
77    memcpy(*dst, src, len);
78    return len;
79}
80
81static int authname_match(enum auth_protos kind, char *name, size_t namelen)
82{
83    if(authnameslen[kind] != namelen)
84	return 0;
85    if(memcmp(authnames[kind], name, namelen))
86	return 0;
87    return 1;
88}
89
90#define SIN6_ADDR(s) (&((struct sockaddr_in6 *)s)->sin6_addr)
91
92static Xauth *get_authptr(struct sockaddr *sockname, unsigned int socknamelen,
93                          int display)
94{
95    char *addr = 0;
96    int addrlen = 0;
97    unsigned short family;
98    char hostnamebuf[256];   /* big enough for max hostname */
99    char dispbuf[40];   /* big enough to hold more than 2^64 base 10 */
100    int dispbuflen;
101
102    family = FamilyLocal; /* 256 */
103    switch(sockname->sa_family)
104    {
105#ifdef AF_INET6
106    case AF_INET6:
107        addr = (char *) SIN6_ADDR(sockname);
108        addrlen = sizeof(*SIN6_ADDR(sockname));
109        if(!IN6_IS_ADDR_V4MAPPED(SIN6_ADDR(sockname)))
110        {
111            if(!IN6_IS_ADDR_LOOPBACK(SIN6_ADDR(sockname)))
112                family = XCB_FAMILY_INTERNET_6;
113            break;
114        }
115        addr += 12;
116        /* if v4-mapped, fall through. */
117#endif
118    case AF_INET:
119        if(!addr)
120            addr = (char *) &((struct sockaddr_in *)sockname)->sin_addr;
121        addrlen = sizeof(((struct sockaddr_in *)sockname)->sin_addr);
122        if(*(in_addr_t *) addr != htonl(INADDR_LOOPBACK))
123            family = XCB_FAMILY_INTERNET;
124        break;
125    case AF_UNIX:
126        break;
127    default:
128        return 0;   /* cannot authenticate this family */
129    }
130
131    dispbuflen = snprintf(dispbuf, sizeof(dispbuf), "%d", display);
132    if(dispbuflen < 0)
133        return 0;
134    /* snprintf may have truncate our text */
135    dispbuflen = MIN(dispbuflen, sizeof(dispbuf) - 1);
136
137    if (family == FamilyLocal) {
138        if (gethostname(hostnamebuf, sizeof(hostnamebuf)) == -1)
139            return 0;   /* do not know own hostname */
140        addr = hostnamebuf;
141        addrlen = strlen(addr);
142    }
143
144    return XauGetBestAuthByAddr (family,
145                                 (unsigned short) addrlen, addr,
146                                 (unsigned short) dispbuflen, dispbuf,
147                                 N_AUTH_PROTOS, authnames, authnameslen);
148}
149
150#ifdef HASXDMAUTH
151static int next_nonce(void)
152{
153    static int nonce = 0;
154    static pthread_mutex_t nonce_mutex = PTHREAD_MUTEX_INITIALIZER;
155    int ret;
156    pthread_mutex_lock(&nonce_mutex);
157    ret = nonce++;
158    pthread_mutex_unlock(&nonce_mutex);
159    return ret;
160}
161
162static void do_append(char *buf, int *idxp, void *val, size_t valsize) {
163    memcpy(buf + *idxp, val, valsize);
164    *idxp += valsize;
165}
166#endif
167
168static int compute_auth(xcb_auth_info_t *info, Xauth *authptr, struct sockaddr *sockname)
169{
170    if (authname_match(AUTH_MC1, authptr->name, authptr->name_length)) {
171        info->datalen = memdup(&info->data, authptr->data, authptr->data_length);
172        if(!info->datalen)
173            return 0;
174        return 1;
175    }
176#ifdef HASXDMAUTH
177#define APPEND(buf,idx,val) do_append((buf),&(idx),&(val),sizeof(val))
178    if (authname_match(AUTH_XA1, authptr->name, authptr->name_length)) {
179	int j;
180
181	info->data = malloc(192 / 8);
182	if(!info->data)
183	    return 0;
184
185	for (j = 0; j < 8; j++)
186	    info->data[j] = authptr->data[j];
187	switch(sockname->sa_family) {
188        case AF_INET:
189            /*block*/ {
190	    struct sockaddr_in *si = (struct sockaddr_in *) sockname;
191	    APPEND(info->data, j, si->sin_addr.s_addr);
192	    APPEND(info->data, j, si->sin_port);
193	}
194	break;
195#ifdef AF_INET6
196        case AF_INET6:
197            /*block*/ {
198            struct sockaddr_in6 *si6 = (struct sockaddr_in6 *) sockname;
199            if(IN6_IS_ADDR_V4MAPPED(SIN6_ADDR(sockname)))
200            {
201                do_append(info->data, &j, &si6->sin6_addr.s6_addr[12], 4);
202                APPEND(info->data, j, si6->sin6_port);
203            }
204            else
205            {
206                /* XDM-AUTHORIZATION-1 does not handle IPv6 correctly.  Do the
207                   same thing Xlib does: use all zeroes for the 4-byte address
208                   and 2-byte port number. */
209                uint32_t fakeaddr = 0;
210                uint16_t fakeport = 0;
211                APPEND(info->data, j, fakeaddr);
212                APPEND(info->data, j, fakeport);
213            }
214        }
215        break;
216#endif
217        case AF_UNIX:
218            /*block*/ {
219	    uint32_t fakeaddr = htonl(0xffffffff - next_nonce());
220	    uint16_t fakeport = htons(getpid());
221	    APPEND(info->data, j, fakeaddr);
222	    APPEND(info->data, j, fakeport);
223	}
224	break;
225        default:
226            free(info->data);
227            return 0;   /* do not know how to build this */
228	}
229	{
230	    uint32_t now = htonl(time(0));
231	    APPEND(info->data, j, now);
232	}
233	assert(j <= 192 / 8);
234	while (j < 192 / 8)
235	    info->data[j++] = 0;
236	info->datalen = j;
237	XdmcpWrap ((unsigned char *) info->data, (unsigned char *) authptr->data + 8, (unsigned char *) info->data, info->datalen);
238	return 1;
239    }
240#undef APPEND
241#endif
242
243    return 0;   /* Unknown authorization type */
244}
245
246int _xcb_get_auth_info(int fd, xcb_auth_info_t *info, int display)
247{
248    /* code adapted from Xlib/ConnDis.c, xtrans/Xtranssocket.c,
249       xtrans/Xtransutils.c */
250    char sockbuf[sizeof(struct sockaddr) + MAXPATHLEN];
251    unsigned int socknamelen = sizeof(sockbuf);   /* need extra space */
252    struct sockaddr *sockname = (struct sockaddr *) &sockbuf;
253    int gotsockname = 0;
254    Xauth *authptr = 0;
255    int ret = 1;
256
257    /* Some systems like hpux or Hurd do not expose peer names
258     * for UNIX Domain Sockets, but this is irrelevant,
259     * since compute_auth() ignores the peer name in this
260     * case anyway.*/
261    if (getpeername(fd, sockname, &socknamelen) == -1)
262    {
263        if (getsockname(fd, sockname, &socknamelen) == -1)
264            return 0;   /* can only authenticate sockets */
265        if (sockname->sa_family != AF_UNIX)
266            return 0;   /* except for AF_UNIX, sockets should have peernames */
267        gotsockname = 1;
268    }
269
270    authptr = get_authptr(sockname, socknamelen, display);
271    if (authptr == 0)
272        return 0;   /* cannot find good auth data */
273
274    info->namelen = memdup(&info->name, authptr->name, authptr->name_length);
275    if (!info->namelen)
276        goto no_auth;   /* out of memory */
277
278    if (!gotsockname && getsockname(fd, sockname, &socknamelen) == -1)
279    {
280        free(info->name);
281        goto no_auth;   /* can only authenticate sockets */
282    }
283
284    ret = compute_auth(info, authptr, sockname);
285    if(!ret)
286    {
287        free(info->name);
288        goto no_auth;   /* cannot build auth record */
289    }
290
291    XauDisposeAuth(authptr);
292    return ret;
293
294 no_auth:
295    info->name = 0;
296    info->namelen = 0;
297    XauDisposeAuth(authptr);
298    return 0;
299}
300