summaryrefslogtreecommitdiff
path: root/src/libsystemd-bus/bus-kernel.c
blob: 65b8b7b961c98f66729ca39dd0bd2e1fb77d8ecb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2013 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <fcntl.h>

#include "util.h"

#include "bus-internal.h"
#include "bus-message.h"
#include "bus-kernel.h"

#define KDBUS_MSG_FOREACH_DATA(d, k)                                    \
        for ((d) = (k)->data;                                           \
             (uint8_t*) (d) < (uint8_t*) (k) + (k)->size;               \
             (d) = (struct kdbus_msg_data*) ((uint8_t*) (d) + ALIGN8((d)->size)))



static int parse_unique_name(const char *s, uint64_t *id) {
        int r;

        assert(s);
        assert(id);

        if (!startswith(s, ":1."))
                return 0;

        r = safe_atou64(s + 3, id);
        if (r < 0)
                return r;

        return 1;
}

static void append_payload_vec(struct kdbus_msg_data **d, const void *p, size_t sz) {
        assert(d);
        assert(p);
        assert(sz > 0);

        (*d)->size = offsetof(struct kdbus_msg_data, vec) + sizeof(struct kdbus_vec);
        (*d)->type = KDBUS_MSG_PAYLOAD_VEC;
        (*d)->vec.address = (uint64_t) p;
        (*d)->vec.size = sz;

        *d = (struct kdbus_msg_data*) ((uint8_t*) *d + ALIGN8((*d)->size));
}

static void append_destination(struct kdbus_msg_data **d, const char *s, size_t length) {
        assert(d);
        assert(d);

        (*d)->size = offsetof(struct kdbus_msg_data, data) + length + 1;
        (*d)->type = KDBUS_MSG_DST_NAME;
        memcpy((*d)->data, s, length + 1);

        *d = (struct kdbus_msg_data*) ((uint8_t*) *d + ALIGN8((*d)->size));
}

static int bus_message_setup_kmsg(sd_bus_message *m) {
        struct kdbus_msg_data *d;
        bool well_known;
        uint64_t unique;
        size_t sz, dl;
        int r;

        assert(m);
        assert(m->sealed);
        assert(!m->kdbus);

        if (m->destination) {
                r = parse_unique_name(m->destination, &unique);
                if (r < 0)
                        return r;

                well_known = r == 0;
        } else
                well_known = false;

        sz = offsetof(struct kdbus_msg, data);

        /* Add in fixed header, fields header, fields header padding and payload */
        sz += 4 * ALIGN8(offsetof(struct kdbus_msg_data, vec) + sizeof(struct kdbus_vec));

        /* Add in well-known destination header */
        if (well_known) {
                dl = strlen(m->destination);
                sz += ALIGN8(offsetof(struct kdbus_msg, data) + dl + 1);
        }

        m->kdbus = malloc0(sz);
        if (!m->kdbus)
                return -ENOMEM;

        m->kdbus->flags =
                ((m->header->flags & SD_BUS_MESSAGE_NO_REPLY_EXPECTED) ? 0 : KDBUS_MSG_FLAGS_EXPECT_REPLY) |
                ((m->header->flags & SD_BUS_MESSAGE_NO_AUTO_START) ? KDBUS_MSG_FLAGS_NO_AUTO_START : 0);
        m->kdbus->dst_id =
                well_known ? 0 :
                m->destination ? unique : (uint64_t) -1;
        m->kdbus->payload_type = KDBUS_PAYLOAD_DBUS1;
        m->kdbus->cookie = m->header->serial;

        m->kdbus->timeout_ns = m->timeout * NSEC_PER_USEC;

        d = m->kdbus->data;

        if (well_known)
                append_destination(&d, m->destination, dl);

        append_payload_vec(&d, m->header, sizeof(*m->header));

        if (m->fields) {
                append_payload_vec(&d, m->fields, m->header->fields_size);

                if (m->header->fields_size % 8 != 0) {
                        static const uint8_t padding[7] = {};

                        append_payload_vec(&d, padding, 8 - (m->header->fields_size % 8));
                }
        }

        if (m->body)
                append_payload_vec(&d, m->body, m->header->body_size);

        m->kdbus->size = (uint8_t*) m - (uint8_t*) m->kdbus;
        assert(m->kdbus->size <= sz);

        return 0;
}

int bus_kernel_take_fd(sd_bus *b) {
        struct kdbus_cmd_hello hello = {};
        int r;

        assert(b);

        r = ioctl(b->input_fd, KDBUS_CMD_HELLO, &hello);
        if (r < 0)
                return -errno;

        if (asprintf(&b->unique_name, ":1.%llu", (unsigned long long) hello.id) < 0)
                return -ENOMEM;

        b->is_kernel = true;

        r = bus_start_running(b);
        if (r < 0)
                return r;

        return 1;
}

int bus_kernel_connect(sd_bus *b) {
        assert(b);
        assert(b->input_fd < 0);
        assert(b->output_fd < 0);
        assert(b->kernel);

        b->input_fd = open(b->kernel, O_RDWR|O_NOCTTY|O_CLOEXEC);
        if (b->input_fd)
                return -errno;

        b->output_fd = b->input_fd;

        return bus_kernel_take_fd(b);
}

int bus_kernel_write_message(sd_bus *bus, sd_bus_message *m) {
        int r;

        assert(bus);
        assert(m);
        assert(bus->state == BUS_RUNNING);

        r = bus_message_setup_kmsg(m);
        if (r < 0)
                return r;

        r = ioctl(bus->output_fd, KDBUS_CMD_MSG_SEND, m->kdbus);
        if (r < 0)
                return errno == EAGAIN ? 0 : -errno;

        return 0;
}

static void close_kdbus_msg(struct kdbus_msg *k) {
        struct kdbus_msg_data *d;

        KDBUS_MSG_FOREACH_DATA(d, k) {

                if (d->type != KDBUS_MSG_UNIX_FDS)
                        continue;

                close_many(d->fds, (d->size - offsetof(struct kdbus_msg_data, fds)) / sizeof(int));
        }
}

static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k, sd_bus_message **ret) {
        sd_bus_message *m = NULL;
        struct kdbus_msg_data *d;
        unsigned n_payload = 0, n_fds = 0;
        _cleanup_free_ int *fds = NULL;
        struct bus_header *h = NULL;
        size_t total, n_bytes = 0, idx = 0;
        int r;

        assert(bus);
        assert(k);
        assert(ret);

        if (k->payload_type != KDBUS_PAYLOAD_DBUS1)
                return 0;

        KDBUS_MSG_FOREACH_DATA(d, k) {
                size_t l;

                l = d->size - offsetof(struct kdbus_msg_data, data);

                if (d->type == KDBUS_MSG_PAYLOAD) {

                        if (!h) {
                                if (l < sizeof(struct bus_header))
                                        return -EBADMSG;

                                h = (struct bus_header*) d->data;
                        }

                        n_payload++;
                        n_bytes += l;

                } else if (d->type == KDBUS_MSG_UNIX_FDS) {
                        int *f;
                        unsigned j;

                        j = l / sizeof(int);
                        f = realloc(fds, sizeof(int) * (n_fds + j));
                        if (!f)
                                return -ENOMEM;

                        fds = f;
                        memcpy(fds + n_fds, d->fds, j);
                        n_fds += j;
                }
        }

        if (!h)
                return -EBADMSG;

        r = bus_header_size(h, &total);
        if (r < 0)
                return r;

        if (n_bytes != total)
                return -EBADMSG;

        r = bus_message_from_header(h, sizeof(struct bus_header), fds, n_fds, NULL, NULL, 0, &m);
        if (r < 0)
                return r;

        KDBUS_MSG_FOREACH_DATA(d, k) {
                size_t l;

                if (d->type != KDBUS_MSG_PAYLOAD)
                        continue;

                l = d->size - offsetof(struct kdbus_msg_data, data);

                if (idx == sizeof(struct bus_header) &&
                    l == BUS_MESSAGE_FIELDS_SIZE(m))
                        m->fields = d->data;
                else if (idx == sizeof(struct bus_header) + ALIGN8(BUS_MESSAGE_FIELDS_SIZE(m)) &&
                         l == BUS_MESSAGE_BODY_SIZE(m))
                        m->body = d->data;
                else {
                        sd_bus_message_unref(m);
                        return -EBADMSG;
                }

                idx += l;
        }

        r = bus_message_parse_fields(m);
        if (r < 0) {
                sd_bus_message_unref(m);
                return r;
        }

        /* We take possession of the kmsg struct now */
        m->kdbus = k;
        m->free_kdbus = true;
        m->free_fds = true;

        fds = NULL;

        *ret = m;
        return 1;
}

int bus_kernel_read_message(sd_bus *bus, sd_bus_message **m) {
        struct kdbus_msg *k;
        size_t sz = 128;
        int r;

        assert(bus);
        assert(m);

        for (;;) {
                void *q;

                q = realloc(bus->rbuffer, sz);
                if (!q)
                        return -errno;

                k = bus->rbuffer = q;
                k->size = sz;

                r = ioctl(bus->input_fd, KDBUS_CMD_MSG_RECV, bus->rbuffer);
                if (r >= 0)
                        break;

                if (errno == EAGAIN)
                        return 0;

                if (errno != -EMSGSIZE)
                        return -errno;

                sz *= 2;
        }

        r = bus_kernel_make_message(bus, k, m);
        if (r > 0)
                bus->rbuffer = NULL;
        else
                close_kdbus_msg(k);

        return r;
}

int bus_kernel_create(const char *name, char **s) {
        struct kdbus_cmd_fname *fname;
        size_t l;
        int fd;
        char *p;

        assert(name);
        assert(s);

        fd = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
        if (fd < 0)
                return -errno;

        l = strlen(name);
        fname = alloca(offsetof(struct kdbus_cmd_fname, name) + DECIMAL_STR_MAX(uid_t) + 1 + l + 1);
        sprintf(fname->name, "%lu-%s", (unsigned long) getuid(), name);
        fname->size = offsetof(struct kdbus_cmd_fname, name) + strlen(fname->name) + 1;
        fname->kernel_flags = KDBUS_CMD_FNAME_ACCESS_WORLD;
        fname->user_flags = 0;

        p = strjoin("/dev/kdbus/", fname->name, "/bus", NULL);
        if (!p)
                return -ENOMEM;

        if (ioctl(fd, KDBUS_CMD_BUS_MAKE, &fname) < 0) {
                close_nointr_nofail(fd);
                free(p);
                return -errno;
        }

        if (s)
                *s = p;

        return fd;
}