xcb_auth.c revision b20a2039 
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, int display)
93{
94    char *addr = 0;
95    int addrlen = 0;
96    unsigned short family;
97    char hostnamebuf[256];   /* big enough for max hostname */
98    char dispbuf[40];   /* big enough to hold more than 2^64 base 10 */
99    int dispbuflen;
100
101    family = FamilyLocal; /* 256 */
102    switch(sockname->sa_family)
103    {
104#ifdef AF_INET6
105    case AF_INET6:
106        addr = (char *) SIN6_ADDR(sockname);
107        addrlen = sizeof(*SIN6_ADDR(sockname));
108        if(!IN6_IS_ADDR_V4MAPPED(SIN6_ADDR(sockname)))
109        {
110            if(!IN6_IS_ADDR_LOOPBACK(SIN6_ADDR(sockname)))
111                family = XCB_FAMILY_INTERNET_6;
112            break;
113        }
114        addr += 12;
115        /* if v4-mapped, fall through. */
116#endif
117    case AF_INET:
118        if(!addr)
119            addr = (char *) &((struct sockaddr_in *)sockname)->sin_addr;
120        addrlen = sizeof(((struct sockaddr_in *)sockname)->sin_addr);
121        if(*(in_addr_t *) addr != htonl(INADDR_LOOPBACK))
122            family = XCB_FAMILY_INTERNET;
123        break;
124    case AF_UNIX:
125        break;
126    default:
127        return 0;   /* cannot authenticate this family */
128    }
129
130    dispbuflen = snprintf(dispbuf, sizeof(dispbuf), "%d", display);
131    if(dispbuflen < 0)
132        return 0;
133    /* snprintf may have truncate our text */
134    dispbuflen = MIN(dispbuflen, sizeof(dispbuf) - 1);
135
136    if (family == FamilyLocal) {
137        if (gethostname(hostnamebuf, sizeof(hostnamebuf)) == -1)
138            return 0;   /* do not know own hostname */
139        addr = hostnamebuf;
140        addrlen = strlen(addr);
141    }
142
143    return XauGetBestAuthByAddr (family,
144                                 (unsigned short) addrlen, addr,
145                                 (unsigned short) dispbuflen, dispbuf,
146                                 N_AUTH_PROTOS, authnames, authnameslen);
147}
148
149#ifdef HASXDMAUTH
150static int next_nonce(void)
151{
152    static int nonce = 0;
153    static pthread_mutex_t nonce_mutex = PTHREAD_MUTEX_INITIALIZER;
154    int ret;
155    pthread_mutex_lock(&nonce_mutex);
156    ret = nonce++;
157    pthread_mutex_unlock(&nonce_mutex);
158    return ret;
159}
160
161static void do_append(char *buf, int *idxp, void *val, size_t valsize) {
162    memcpy(buf + *idxp, val, valsize);
163    *idxp += valsize;
164}
165#endif
166
167static int compute_auth(xcb_auth_info_t *info, Xauth *authptr, struct sockaddr *sockname)
168{
169    if (authname_match(AUTH_MC1, authptr->name, authptr->name_length)) {
170        info->datalen = memdup(&info->data, authptr->data, authptr->data_length);
171        if(!info->datalen)
172            return 0;
173        return 1;
174    }
175#ifdef HASXDMAUTH
176#define APPEND(buf,idx,val) do_append((buf),&(idx),&(val),sizeof(val))
177    if (authname_match(AUTH_XA1, authptr->name, authptr->name_length)) {
178	int j;
179
180	info->data = malloc(192 / 8);
181	if(!info->data)
182	    return 0;
183
184	for (j = 0; j < 8; j++)
185	    info->data[j] = authptr->data[j];
186	switch(sockname->sa_family) {
187        case AF_INET:
188            /*block*/ {
189	    struct sockaddr_in *si = (struct sockaddr_in *) sockname;
190	    APPEND(info->data, j, si->sin_addr.s_addr);
191	    APPEND(info->data, j, si->sin_port);
192	}
193	break;
194#ifdef AF_INET6
195        case AF_INET6:
196            /*block*/ {
197            struct sockaddr_in6 *si6 = (struct sockaddr_in6 *) sockname;
198            if(IN6_IS_ADDR_V4MAPPED(SIN6_ADDR(sockname)))
199            {
200                do_append(info->data, &j, &si6->sin6_addr.s6_addr[12], 4);
201                APPEND(info->data, j, si6->sin6_port);
202            }
203            else
204            {
205                /* XDM-AUTHORIZATION-1 does not handle IPv6 correctly.  Do the
206                   same thing Xlib does: use all zeroes for the 4-byte address
207                   and 2-byte port number. */
208                uint32_t fakeaddr = 0;
209                uint16_t fakeport = 0;
210                APPEND(info->data, j, fakeaddr);
211                APPEND(info->data, j, fakeport);
212            }
213        }
214        break;
215#endif
216        case AF_UNIX:
217            /*block*/ {
218	    uint32_t fakeaddr = htonl(0xffffffff - next_nonce());
219	    uint16_t fakeport = htons(getpid());
220	    APPEND(info->data, j, fakeaddr);
221	    APPEND(info->data, j, fakeport);
222	}
223	break;
224        default:
225            free(info->data);
226            return 0;   /* do not know how to build this */
227	}
228	{
229	    uint32_t now = htonl(time(0));
230	    APPEND(info->data, j, now);
231	}
232	assert(j <= 192 / 8);
233	while (j < 192 / 8)
234	    info->data[j++] = 0;
235	info->datalen = j;
236	XdmcpWrap ((unsigned char *) info->data, (unsigned char *) authptr->data + 8, (unsigned char *) info->data, info->datalen);
237	return 1;
238    }
239#undef APPEND
240#endif
241
242    return 0;   /* Unknown authorization type */
243}
244
245/* `sockaddr_un.sun_path' typical size usually ranges between 92 and 108 */
246#define INITIAL_SOCKNAME_SLACK 108
247
248/* Return a dynamically allocated socket address structure according
249   to the value returned by either getpeername() or getsockname()
250   (according to POSIX, applications should not assume a particular
251   length for `sockaddr_un.sun_path') */
252static struct sockaddr *get_peer_sock_name(int (*socket_func)(int,
253							      struct sockaddr *,
254							      socklen_t *),
255					   int fd)
256{
257    socklen_t socknamelen = sizeof(struct sockaddr) + INITIAL_SOCKNAME_SLACK;
258    socklen_t actual_socknamelen = socknamelen;
259    struct sockaddr *sockname = malloc(socknamelen), *new_sockname = NULL;
260
261    if (sockname == NULL)
262        return NULL;
263
264    /* Both getpeername() and getsockname() truncates sockname if
265       there is not enough space and set the required length in
266       actual_socknamelen */
267    if (socket_func(fd, sockname, &actual_socknamelen) == -1)
268        goto sock_or_realloc_error;
269
270    if (actual_socknamelen > socknamelen)
271    {
272        socknamelen = actual_socknamelen;
273
274        if ((new_sockname = realloc(sockname, actual_socknamelen)) == NULL ||
275            socket_func(fd, new_sockname, &actual_socknamelen) == -1 ||
276            actual_socknamelen > socknamelen)
277            goto sock_or_realloc_error;
278
279        sockname = new_sockname;
280    }
281
282    return sockname;
283
284 sock_or_realloc_error:
285    free(sockname);
286    return NULL;
287}
288
289int _xcb_get_auth_info(int fd, xcb_auth_info_t *info, int display)
290{
291    /* code adapted from Xlib/ConnDis.c, xtrans/Xtranssocket.c,
292       xtrans/Xtransutils.c */
293    struct sockaddr *sockname = NULL;
294    int gotsockname = 0;
295    Xauth *authptr = 0;
296    int ret = 1;
297
298    /* Some systems like hpux or Hurd do not expose peer names
299     * for UNIX Domain Sockets, but this is irrelevant,
300     * since compute_auth() ignores the peer name in this
301     * case anyway.*/
302    if ((sockname = get_peer_sock_name(getpeername, fd)) == NULL)
303    {
304        if ((sockname = get_peer_sock_name(getsockname, fd)) == NULL)
305            return 0;   /* can only authenticate sockets */
306        if (sockname->sa_family != AF_UNIX)
307        {
308            free(sockname);
309            return 0;   /* except for AF_UNIX, sockets should have peernames */
310        }
311        gotsockname = 1;
312    }
313
314    authptr = get_authptr(sockname, display);
315    if (authptr == 0)
316    {
317        free(sockname);
318        return 0;   /* cannot find good auth data */
319    }
320
321    info->namelen = memdup(&info->name, authptr->name, authptr->name_length);
322    if (!info->namelen)
323        goto no_auth;   /* out of memory */
324
325    if (!gotsockname && (sockname = get_peer_sock_name(getsockname, fd)) == NULL)
326    {
327        free(info->name);
328        goto no_auth;   /* can only authenticate sockets */
329    }
330
331    ret = compute_auth(info, authptr, sockname);
332    if(!ret)
333    {
334        free(info->name);
335        goto no_auth;   /* cannot build auth record */
336    }
337
338    free(sockname);
339    sockname = NULL;
340
341    XauDisposeAuth(authptr);
342    return ret;
343
344 no_auth:
345    free(sockname);
346
347    info->name = 0;
348    info->namelen = 0;
349    XauDisposeAuth(authptr);
350    return 0;
351}
352