service_manager.c revision a573f6a1d9b12393fbdfd2c0850499973849854b 
1/* Copyright 2008 The Android Open Source Project
2 */
3
4#include <stdio.h>
5#include <stdlib.h>
6#include <errno.h>
7#include <fcntl.h>
8
9#include <private/android_filesystem_config.h>
10
11#include "binder.h"
12
13#if 0
14#define ALOGI(x...) fprintf(stderr, "svcmgr: " x)
15#define ALOGE(x...) fprintf(stderr, "svcmgr: " x)
16#else
17#define LOG_TAG "ServiceManager"
18#include <cutils/log.h>
19#endif
20
21/* TODO:
22 * These should come from a config file or perhaps be
23 * based on some namespace rules of some sort (media
24 * uid can register media.*, etc)
25 */
26static struct {
27    unsigned uid;
28    const char *name;
29} allowed[] = {
30    { AID_MEDIA, "media.audio_flinger" },
31    { AID_MEDIA, "media.player" },
32    { AID_MEDIA, "media.camera" },
33    { AID_MEDIA, "media.audio_policy" },
34    { AID_DRM,   "drm.drmManager" },
35    { AID_NFC,   "nfc" },
36    { AID_RADIO, "radio.phone" },
37    { AID_RADIO, "radio.sms" },
38    { AID_RADIO, "radio.phonesubinfo" },
39    { AID_RADIO, "radio.simphonebook" },
40/* TODO: remove after phone services are updated: */
41    { AID_RADIO, "phone" },
42    { AID_RADIO, "sip" },
43    { AID_RADIO, "isms" },
44    { AID_RADIO, "iphonesubinfo" },
45    { AID_RADIO, "simphonebook" },
46};
47
48void *svcmgr_handle;
49
50const char *str8(uint16_t *x)
51{
52    static char buf[128];
53    unsigned max = 127;
54    char *p = buf;
55
56    if (x) {
57        while (*x && max--) {
58            *p++ = *x++;
59        }
60    }
61    *p++ = 0;
62    return buf;
63}
64
65int str16eq(uint16_t *a, const char *b)
66{
67    while (*a && *b)
68        if (*a++ != *b++) return 0;
69    if (*a || *b)
70        return 0;
71    return 1;
72}
73
74int svc_can_register(unsigned uid, uint16_t *name)
75{
76    unsigned n;
77
78    if ((uid == 0) || (uid == AID_SYSTEM))
79        return 1;
80
81    for (n = 0; n < sizeof(allowed) / sizeof(allowed[0]); n++)
82        if ((uid == allowed[n].uid) && str16eq(name, allowed[n].name))
83            return 1;
84
85    return 0;
86}
87
88struct svcinfo
89{
90    struct svcinfo *next;
91    void *ptr;
92    struct binder_death death;
93    int allow_isolated;
94    unsigned len;
95    uint16_t name[0];
96};
97
98struct svcinfo *svclist = 0;
99
100struct svcinfo *find_svc(uint16_t *s16, unsigned len)
101{
102    struct svcinfo *si;
103
104    for (si = svclist; si; si = si->next) {
105        if ((len == si->len) &&
106            !memcmp(s16, si->name, len * sizeof(uint16_t))) {
107            return si;
108        }
109    }
110    return 0;
111}
112
113void svcinfo_death(struct binder_state *bs, void *ptr)
114{
115    struct svcinfo *si = ptr;
116    ALOGI("service '%s' died\n", str8(si->name));
117    if (si->ptr) {
118        binder_release(bs, si->ptr);
119        si->ptr = 0;
120    }
121}
122
123uint16_t svcmgr_id[] = {
124    'a','n','d','r','o','i','d','.','o','s','.',
125    'I','S','e','r','v','i','c','e','M','a','n','a','g','e','r'
126};
127
128
129void *do_find_service(struct binder_state *bs, uint16_t *s, unsigned len, unsigned uid)
130{
131    struct svcinfo *si;
132    si = find_svc(s, len);
133
134//    ALOGI("check_service('%s') ptr = %p\n", str8(s), si ? si->ptr : 0);
135    if (si && si->ptr) {
136        if (!si->allow_isolated) {
137            // If this service doesn't allow access from isolated processes,
138            // then check the uid to see if it is isolated.
139            unsigned appid = uid % AID_USER;
140            if (appid >= AID_ISOLATED_START && appid <= AID_ISOLATED_END) {
141                return 0;
142            }
143        }
144        return si->ptr;
145    } else {
146        return 0;
147    }
148}
149
150int do_add_service(struct binder_state *bs,
151                   uint16_t *s, unsigned len,
152                   void *ptr, unsigned uid, int allow_isolated)
153{
154    struct svcinfo *si;
155    //ALOGI("add_service('%s',%p,%s) uid=%d\n", str8(s), ptr,
156    //        allow_isolated ? "allow_isolated" : "!allow_isolated", uid);
157
158    if (!ptr || (len == 0) || (len > 127))
159        return -1;
160
161    if (!svc_can_register(uid, s)) {
162        ALOGE("add_service('%s',%p) uid=%d - PERMISSION DENIED\n",
163             str8(s), ptr, uid);
164        return -1;
165    }
166
167    si = find_svc(s, len);
168    if (si) {
169        if (si->ptr) {
170            ALOGE("add_service('%s',%p) uid=%d - ALREADY REGISTERED, OVERRIDE\n",
171                 str8(s), ptr, uid);
172            svcinfo_death(bs, si);
173        }
174        si->ptr = ptr;
175    } else {
176        si = malloc(sizeof(*si) + (len + 1) * sizeof(uint16_t));
177        if (!si) {
178            ALOGE("add_service('%s',%p) uid=%d - OUT OF MEMORY\n",
179                 str8(s), ptr, uid);
180            return -1;
181        }
182        si->ptr = ptr;
183        si->len = len;
184        memcpy(si->name, s, (len + 1) * sizeof(uint16_t));
185        si->name[len] = '\0';
186        si->death.func = svcinfo_death;
187        si->death.ptr = si;
188        si->allow_isolated = allow_isolated;
189        si->next = svclist;
190        svclist = si;
191    }
192
193    binder_acquire(bs, ptr);
194    binder_link_to_death(bs, ptr, &si->death);
195    return 0;
196}
197
198int svcmgr_handler(struct binder_state *bs,
199                   struct binder_txn *txn,
200                   struct binder_io *msg,
201                   struct binder_io *reply)
202{
203    struct svcinfo *si;
204    uint16_t *s;
205    unsigned len;
206    void *ptr;
207    uint32_t strict_policy;
208    int allow_isolated;
209
210//    ALOGI("target=%p code=%d pid=%d uid=%d\n",
211//         txn->target, txn->code, txn->sender_pid, txn->sender_euid);
212
213    if (txn->target != svcmgr_handle)
214        return -1;
215
216    // Equivalent to Parcel::enforceInterface(), reading the RPC
217    // header with the strict mode policy mask and the interface name.
218    // Note that we ignore the strict_policy and don't propagate it
219    // further (since we do no outbound RPCs anyway).
220    strict_policy = bio_get_uint32(msg);
221    s = bio_get_string16(msg, &len);
222    if ((len != (sizeof(svcmgr_id) / 2)) ||
223        memcmp(svcmgr_id, s, sizeof(svcmgr_id))) {
224        fprintf(stderr,"invalid id %s\n", str8(s));
225        return -1;
226    }
227
228    switch(txn->code) {
229    case SVC_MGR_GET_SERVICE:
230    case SVC_MGR_CHECK_SERVICE:
231        s = bio_get_string16(msg, &len);
232        ptr = do_find_service(bs, s, len, txn->sender_euid);
233        if (!ptr)
234            break;
235        bio_put_ref(reply, ptr);
236        return 0;
237
238    case SVC_MGR_ADD_SERVICE:
239        s = bio_get_string16(msg, &len);
240        ptr = bio_get_ref(msg);
241        allow_isolated = bio_get_uint32(msg) ? 1 : 0;
242        if (do_add_service(bs, s, len, ptr, txn->sender_euid, allow_isolated))
243            return -1;
244        break;
245
246    case SVC_MGR_LIST_SERVICES: {
247        unsigned n = bio_get_uint32(msg);
248
249        si = svclist;
250        while ((n-- > 0) && si)
251            si = si->next;
252        if (si) {
253            bio_put_string16(reply, si->name);
254            return 0;
255        }
256        return -1;
257    }
258    default:
259        ALOGE("unknown code %d\n", txn->code);
260        return -1;
261    }
262
263    bio_put_uint32(reply, 0);
264    return 0;
265}
266
267int main(int argc, char **argv)
268{
269    struct binder_state *bs;
270    void *svcmgr = BINDER_SERVICE_MANAGER;
271
272    bs = binder_open(128*1024);
273
274    if (binder_become_context_manager(bs)) {
275        ALOGE("cannot become context manager (%s)\n", strerror(errno));
276        return -1;
277    }
278
279    svcmgr_handle = svcmgr;
280    binder_loop(bs, svcmgr_handler);
281    return 0;
282}
283