src/libsystemd/sd-bus/bus-socket.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2013 Lennart Poettering
   6 ***/
   7
   8 #include <endian.h>
   9 #include <poll.h>
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12
  13 #include "sd-bus.h"
  14 #include "sd-daemon.h"
  15
  16 #include "alloc-util.h"
  17 #include "bus-internal.h"
  18 #include "bus-message.h"
  19 #include "bus-socket.h"
  20 #include "fd-util.h"
  21 #include "format-util.h"
  22 #include "fs-util.h"
  23 #include "hexdecoct.h"
  24 #include "io-util.h"
  25 #include "macro.h"
  26 #include "missing.h"
  27 #include "path-util.h"
  28 #include "process-util.h"
  29 #include "selinux-util.h"
  30 #include "signal-util.h"
  31 #include "stdio-util.h"
  32 #include "string-util.h"
  33 #include "user-util.h"
  34 #include "utf8.h"
  35 #include "util.h"
  36
  37 #define SNDBUF_SIZE (8*1024*1024)
  38
  39 static void iovec_advance(struct iovec iov[], unsigned *idx, size_t size) {
  40
  41         while (size > 0) {
  42                 struct iovec *i = iov + *idx;
  43
  44                 if (i->iov_len > size) {
  45                         i->iov_base = (uint8_t*) i->iov_base + size;
  46                         i->iov_len -= size;
  47                         return;
  48                 }
  49
  50                 size -= i->iov_len;
  51
  52                 i->iov_base = NULL;
  53                 i->iov_len = 0;
  54
  55                 (*idx)++;
  56         }
  57 }
  58
  59 static int append_iovec(sd_bus_message *m, const void *p, size_t sz) {
  60         assert(m);
  61         assert(p);
  62         assert(sz > 0);
  63
  64         m->iovec[m->n_iovec].iov_base = (void*) p;
  65         m->iovec[m->n_iovec].iov_len = sz;
  66         m->n_iovec++;
  67
  68         return 0;
  69 }
  70
  71 static int bus_message_setup_iovec(sd_bus_message *m) {
  72         struct bus_body_part *part;
  73         unsigned n, i;
  74         int r;
  75
  76         assert(m);
  77         assert(m->sealed);
  78
  79         if (m->n_iovec > 0)
  80                 return 0;
  81
  82         assert(!m->iovec);
  83
  84         n = 1 + m->n_body_parts;
  85         if (n < ELEMENTSOF(m->iovec_fixed))
  86                 m->iovec = m->iovec_fixed;
  87         else {
  88                 m->iovec = new(struct iovec, n);
  89                 if (!m->iovec) {
  90                         r = -ENOMEM;
  91                         goto fail;
  92                 }
  93         }
  94
  95         r = append_iovec(m, m->header, BUS_MESSAGE_BODY_BEGIN(m));
  96         if (r < 0)
  97                 goto fail;
  98
  99         MESSAGE_FOREACH_PART(part, i, m)  {
 100                 r = bus_body_part_map(part);
 101                 if (r < 0)
 102                         goto fail;
 103
 104                 r = append_iovec(m, part->data, part->size);
 105                 if (r < 0)
 106                         goto fail;
 107         }
 108
 109         assert(n == m->n_iovec);
 110
 111         return 0;
 112
 113 fail:
 114         m->poisoned = true;
 115         return r;
 116 }
 117
 118 bool bus_socket_auth_needs_write(sd_bus *b) {
 119
 120         unsigned i;
 121
 122         if (b->auth_index >= ELEMENTSOF(b->auth_iovec))
 123                 return false;
 124
 125         for (i = b->auth_index; i < ELEMENTSOF(b->auth_iovec); i++) {
 126                 struct iovec *j = b->auth_iovec + i;
 127
 128                 if (j->iov_len > 0)
 129                         return true;
 130         }
 131
 132         return false;
 133 }
 134
 135 static int bus_socket_write_auth(sd_bus *b) {
 136         ssize_t k;
 137
 138         assert(b);
 139         assert(b->state == BUS_AUTHENTICATING);
 140
 141         if (!bus_socket_auth_needs_write(b))
 142                 return 0;
 143
 144         if (b->prefer_writev)
 145                 k = writev(b->output_fd, b->auth_iovec + b->auth_index, ELEMENTSOF(b->auth_iovec) - b->auth_index);
 146         else {
 147                 struct msghdr mh;
 148                 zero(mh);
 149
 150                 mh.msg_iov = b->auth_iovec + b->auth_index;
 151                 mh.msg_iovlen = ELEMENTSOF(b->auth_iovec) - b->auth_index;
 152
 153                 k = sendmsg(b->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
 154                 if (k < 0 && errno == ENOTSOCK) {
 155                         b->prefer_writev = true;
 156                         k = writev(b->output_fd, b->auth_iovec + b->auth_index, ELEMENTSOF(b->auth_iovec) - b->auth_index);
 157                 }
 158         }
 159
 160         if (k < 0)
 161                 return errno == EAGAIN ? 0 : -errno;
 162
 163         iovec_advance(b->auth_iovec, &b->auth_index, (size_t) k);
 164         return 1;
 165 }
 166
 167 static int bus_socket_auth_verify_client(sd_bus *b) {
 168         char *e, *f, *start;
 169         sd_id128_t peer;
 170         unsigned i;
 171         int r;
 172
 173         assert(b);
 174
 175         /* We expect two response lines: "OK" and possibly
 176          * "AGREE_UNIX_FD" */
 177
 178         e = memmem_safe(b->rbuffer, b->rbuffer_size, "\r\n", 2);
 179         if (!e)
 180                 return 0;
 181
 182         if (b->accept_fd) {
 183                 f = memmem(e + 2, b->rbuffer_size - (e - (char*) b->rbuffer) - 2, "\r\n", 2);
 184                 if (!f)
 185                         return 0;
 186
 187                 start = f + 2;
 188         } else {
 189                 f = NULL;
 190                 start = e + 2;
 191         }
 192
 193         /* Nice! We got all the lines we need. First check the OK
 194          * line */
 195
 196         if (e - (char*) b->rbuffer != 3 + 32)
 197                 return -EPERM;
 198
 199         if (memcmp(b->rbuffer, "OK ", 3))
 200                 return -EPERM;
 201
 202         b->auth = b->anonymous_auth ? BUS_AUTH_ANONYMOUS : BUS_AUTH_EXTERNAL;
 203
 204         for (i = 0; i < 32; i += 2) {
 205                 int x, y;
 206
 207                 x = unhexchar(((char*) b->rbuffer)[3 + i]);
 208                 y = unhexchar(((char*) b->rbuffer)[3 + i + 1]);
 209
 210                 if (x < 0 || y < 0)
 211                         return -EINVAL;
 212
 213                 peer.bytes[i/2] = ((uint8_t) x << 4 | (uint8_t) y);
 214         }
 215
 216         if (!sd_id128_is_null(b->server_id) &&
 217             !sd_id128_equal(b->server_id, peer))
 218                 return -EPERM;
 219
 220         b->server_id = peer;
 221
 222         /* And possibly check the second line, too */
 223
 224         if (f)
 225                 b->can_fds =
 226                         (f - e == STRLEN("\r\nAGREE_UNIX_FD")) &&
 227                         memcmp(e + 2, "AGREE_UNIX_FD",
 228                                STRLEN("AGREE_UNIX_FD")) == 0;
 229
 230         b->rbuffer_size -= (start - (char*) b->rbuffer);
 231         memmove(b->rbuffer, start, b->rbuffer_size);
 232
 233         r = bus_start_running(b);
 234         if (r < 0)
 235                 return r;
 236
 237         return 1;
 238 }
 239
 240 static bool line_equals(const char *s, size_t m, const char *line) {
 241         size_t l;
 242
 243         l = strlen(line);
 244         if (l != m)
 245                 return false;
 246
 247         return memcmp(s, line, l) == 0;
 248 }
 249
 250 static bool line_begins(const char *s, size_t m, const char *word) {
 251         const char *p;
 252
 253         p = memory_startswith(s, m, word);
 254         if (!p)
 255                 return false;
 256
 257         return IN_SET(*p, 0, ' ');
 258 }
 259
 260 static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) {
 261         _cleanup_free_ char *token = NULL;
 262         size_t len;
 263         int r;
 264
 265         if (!b->anonymous_auth)
 266                 return 0;
 267
 268         if (l <= 0)
 269                 return 1;
 270
 271         assert(p[0] == ' ');
 272         p++; l--;
 273
 274         if (l % 2 != 0)
 275                 return 0;
 276
 277         r = unhexmem(p, l, (void **) &token, &len);
 278         if (r < 0)
 279                 return 0;
 280
 281         if (memchr(token, 0, len))
 282                 return 0;
 283
 284         return !!utf8_is_valid(token);
 285 }
 286
 287 static int verify_external_token(sd_bus *b, const char *p, size_t l) {
 288         _cleanup_free_ char *token = NULL;
 289         size_t len;
 290         uid_t u;
 291         int r;
 292
 293         /* We don't do any real authentication here. Instead, we if
 294          * the owner of this bus wanted authentication he should have
 295          * checked SO_PEERCRED before even creating the bus object. */
 296
 297         if (!b->anonymous_auth && !b->ucred_valid)
 298                 return 0;
 299
 300         if (l <= 0)
 301                 return 1;
 302
 303         assert(p[0] == ' ');
 304         p++; l--;
 305
 306         if (l % 2 != 0)
 307                 return 0;
 308
 309         r = unhexmem(p, l, (void**) &token, &len);
 310         if (r < 0)
 311                 return 0;
 312
 313         if (memchr(token, 0, len))
 314                 return 0;
 315
 316         r = parse_uid(token, &u);
 317         if (r < 0)
 318                 return 0;
 319
 320         /* We ignore the passed value if anonymous authentication is
 321          * on anyway. */
 322         if (!b->anonymous_auth && u != b->ucred.uid)
 323                 return 0;
 324
 325         return 1;
 326 }
 327
 328 static int bus_socket_auth_write(sd_bus *b, const char *t) {
 329         char *p;
 330         size_t l;
 331
 332         assert(b);
 333         assert(t);
 334
 335         /* We only make use of the first iovec */
 336         assert(IN_SET(b->auth_index, 0, 1));
 337
 338         l = strlen(t);
 339         p = malloc(b->auth_iovec[0].iov_len + l);
 340         if (!p)
 341                 return -ENOMEM;
 342
 343         memcpy_safe(p, b->auth_iovec[0].iov_base, b->auth_iovec[0].iov_len);
 344         memcpy(p + b->auth_iovec[0].iov_len, t, l);
 345
 346         b->auth_iovec[0].iov_base = p;
 347         b->auth_iovec[0].iov_len += l;
 348
 349         free(b->auth_buffer);
 350         b->auth_buffer = p;
 351         b->auth_index = 0;
 352         return 0;
 353 }
 354
 355 static int bus_socket_auth_write_ok(sd_bus *b) {
 356         char t[3 + 32 + 2 + 1];
 357
 358         assert(b);
 359
 360         xsprintf(t, "OK " SD_ID128_FORMAT_STR "\r\n", SD_ID128_FORMAT_VAL(b->server_id));
 361
 362         return bus_socket_auth_write(b, t);
 363 }
 364
 365 static int bus_socket_auth_verify_server(sd_bus *b) {
 366         char *e;
 367         const char *line;
 368         size_t l;
 369         bool processed = false;
 370         int r;
 371
 372         assert(b);
 373
 374         if (b->rbuffer_size < 1)
 375                 return 0;
 376
 377         /* First char must be a NUL byte */
 378         if (*(char*) b->rbuffer != 0)
 379                 return -EIO;
 380
 381         if (b->rbuffer_size < 3)
 382                 return 0;
 383
 384         /* Begin with the first line */
 385         if (b->auth_rbegin <= 0)
 386                 b->auth_rbegin = 1;
 387
 388         for (;;) {
 389                 /* Check if line is complete */
 390                 line = (char*) b->rbuffer + b->auth_rbegin;
 391                 e = memmem(line, b->rbuffer_size - b->auth_rbegin, "\r\n", 2);
 392                 if (!e)
 393                         return processed;
 394
 395                 l = e - line;
 396
 397                 if (line_begins(line, l, "AUTH ANONYMOUS")) {
 398
 399                         r = verify_anonymous_token(b, line + 14, l - 14);
 400                         if (r < 0)
 401                                 return r;
 402                         if (r == 0)
 403                                 r = bus_socket_auth_write(b, "REJECTED\r\n");
 404                         else {
 405                                 b->auth = BUS_AUTH_ANONYMOUS;
 406                                 r = bus_socket_auth_write_ok(b);
 407                         }
 408
 409                 } else if (line_begins(line, l, "AUTH EXTERNAL")) {
 410
 411                         r = verify_external_token(b, line + 13, l - 13);
 412                         if (r < 0)
 413                                 return r;
 414                         if (r == 0)
 415                                 r = bus_socket_auth_write(b, "REJECTED\r\n");
 416                         else {
 417                                 b->auth = BUS_AUTH_EXTERNAL;
 418                                 r = bus_socket_auth_write_ok(b);
 419                         }
 420
 421                 } else if (line_begins(line, l, "AUTH"))
 422                         r = bus_socket_auth_write(b, "REJECTED EXTERNAL ANONYMOUS\r\n");
 423                 else if (line_equals(line, l, "CANCEL") ||
 424                          line_begins(line, l, "ERROR")) {
 425
 426                         b->auth = _BUS_AUTH_INVALID;
 427                         r = bus_socket_auth_write(b, "REJECTED\r\n");
 428
 429                 } else if (line_equals(line, l, "BEGIN")) {
 430
 431                         if (b->auth == _BUS_AUTH_INVALID)
 432                                 r = bus_socket_auth_write(b, "ERROR\r\n");
 433                         else {
 434                                 /* We can't leave from the auth phase
 435                                  * before we haven't written
 436                                  * everything queued, so let's check
 437                                  * that */
 438
 439                                 if (bus_socket_auth_needs_write(b))
 440                                         return 1;
 441
 442                                 b->rbuffer_size -= (e + 2 - (char*) b->rbuffer);
 443                                 memmove(b->rbuffer, e + 2, b->rbuffer_size);
 444                                 return bus_start_running(b);
 445                         }
 446
 447                 } else if (line_begins(line, l, "DATA")) {
 448
 449                         if (b->auth == _BUS_AUTH_INVALID)
 450                                 r = bus_socket_auth_write(b, "ERROR\r\n");
 451                         else {
 452                                 if (b->auth == BUS_AUTH_ANONYMOUS)
 453                                         r = verify_anonymous_token(b, line + 4, l - 4);
 454                                 else
 455                                         r = verify_external_token(b, line + 4, l - 4);
 456
 457                                 if (r < 0)
 458                                         return r;
 459                                 if (r == 0) {
 460                                         b->auth = _BUS_AUTH_INVALID;
 461                                         r = bus_socket_auth_write(b, "REJECTED\r\n");
 462                                 } else
 463                                         r = bus_socket_auth_write_ok(b);
 464                         }
 465                 } else if (line_equals(line, l, "NEGOTIATE_UNIX_FD")) {
 466                         if (b->auth == _BUS_AUTH_INVALID || !b->accept_fd)
 467                                 r = bus_socket_auth_write(b, "ERROR\r\n");
 468                         else {
 469                                 b->can_fds = true;
 470                                 r = bus_socket_auth_write(b, "AGREE_UNIX_FD\r\n");
 471                         }
 472                 } else
 473                         r = bus_socket_auth_write(b, "ERROR\r\n");
 474
 475                 if (r < 0)
 476                         return r;
 477
 478                 b->auth_rbegin = e + 2 - (char*) b->rbuffer;
 479
 480                 processed = true;
 481         }
 482 }
 483
 484 static int bus_socket_auth_verify(sd_bus *b) {
 485         assert(b);
 486
 487         if (b->is_server)
 488                 return bus_socket_auth_verify_server(b);
 489         else
 490                 return bus_socket_auth_verify_client(b);
 491 }
 492
 493 static int bus_socket_read_auth(sd_bus *b) {
 494         struct msghdr mh;
 495         struct iovec iov = {};
 496         size_t n;
 497         ssize_t k;
 498         int r;
 499         void *p;
 500         union {
 501                 struct cmsghdr cmsghdr;
 502                 uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
 503         } control;
 504         bool handle_cmsg = false;
 505
 506         assert(b);
 507         assert(b->state == BUS_AUTHENTICATING);
 508
 509         r = bus_socket_auth_verify(b);
 510         if (r != 0)
 511                 return r;
 512
 513         n = MAX(256u, b->rbuffer_size * 2);
 514
 515         if (n > BUS_AUTH_SIZE_MAX)
 516                 n = BUS_AUTH_SIZE_MAX;
 517
 518         if (b->rbuffer_size >= n)
 519                 return -ENOBUFS;
 520
 521         p = realloc(b->rbuffer, n);
 522         if (!p)
 523                 return -ENOMEM;
 524
 525         b->rbuffer = p;
 526
 527         iov.iov_base = (uint8_t*) b->rbuffer + b->rbuffer_size;
 528         iov.iov_len = n - b->rbuffer_size;
 529
 530         if (b->prefer_readv)
 531                 k = readv(b->input_fd, &iov, 1);
 532         else {
 533                 zero(mh);
 534                 mh.msg_iov = &iov;
 535                 mh.msg_iovlen = 1;
 536                 mh.msg_control = &control;
 537                 mh.msg_controllen = sizeof(control);
 538
 539                 k = recvmsg(b->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
 540                 if (k < 0 && errno == ENOTSOCK) {
 541                         b->prefer_readv = true;
 542                         k = readv(b->input_fd, &iov, 1);
 543                 } else
 544                         handle_cmsg = true;
 545         }
 546         if (k < 0)
 547                 return errno == EAGAIN ? 0 : -errno;
 548         if (k == 0)
 549                 return -ECONNRESET;
 550
 551         b->rbuffer_size += k;
 552
 553         if (handle_cmsg) {
 554                 struct cmsghdr *cmsg;
 555
 556                 CMSG_FOREACH(cmsg, &mh)
 557                         if (cmsg->cmsg_level == SOL_SOCKET &&
 558                             cmsg->cmsg_type == SCM_RIGHTS) {
 559                                 int j;
 560
 561                                 /* Whut? We received fds during the auth
 562                                  * protocol? Somebody is playing games with
 563                                  * us. Close them all, and fail */
 564                                 j = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
 565                                 close_many((int*) CMSG_DATA(cmsg), j);
 566                                 return -EIO;
 567                         } else
 568                                 log_debug("Got unexpected auxiliary data with level=%d and type=%d",
 569                                           cmsg->cmsg_level, cmsg->cmsg_type);
 570         }
 571
 572         r = bus_socket_auth_verify(b);
 573         if (r != 0)
 574                 return r;
 575
 576         return 1;
 577 }
 578
 579 void bus_socket_setup(sd_bus *b) {
 580         assert(b);
 581
 582         /* Increase the buffers to 8 MB */
 583         (void) fd_inc_rcvbuf(b->input_fd, SNDBUF_SIZE);
 584         (void) fd_inc_sndbuf(b->output_fd, SNDBUF_SIZE);
 585
 586         b->message_version = 1;
 587         b->message_endian = 0;
 588 }
 589
 590 static void bus_get_peercred(sd_bus *b) {
 591         int r;
 592
 593         assert(b);
 594         assert(!b->ucred_valid);
 595         assert(!b->label);
 596         assert(b->n_groups == (size_t) -1);
 597
 598         /* Get the peer for socketpair() sockets */
 599         b->ucred_valid = getpeercred(b->input_fd, &b->ucred) >= 0;
 600
 601         /* Get the SELinux context of the peer */
 602         r = getpeersec(b->input_fd, &b->label);
 603         if (r < 0 && !IN_SET(r, -EOPNOTSUPP, -ENOPROTOOPT))
 604                 log_debug_errno(r, "Failed to determine peer security context: %m");
 605
 606         /* Get the list of auxiliary groups of the peer */
 607         r = getpeergroups(b->input_fd, &b->groups);
 608         if (r >= 0)
 609                 b->n_groups = (size_t) r;
 610         else if (!IN_SET(r, -EOPNOTSUPP, -ENOPROTOOPT))
 611                 log_debug_errno(r, "Failed to determine peer's group list: %m");
 612 }
 613
 614 static int bus_socket_start_auth_client(sd_bus *b) {
 615         size_t l;
 616         const char *auth_suffix, *auth_prefix;
 617
 618         assert(b);
 619
 620         if (b->anonymous_auth) {
 621                 auth_prefix = "\0AUTH ANONYMOUS ";
 622
 623                 /* For ANONYMOUS auth we send some arbitrary "trace" string */
 624                 l = 9;
 625                 b->auth_buffer = hexmem("anonymous", l);
 626         } else {
 627                 char text[DECIMAL_STR_MAX(uid_t) + 1];
 628
 629                 auth_prefix = "\0AUTH EXTERNAL ";
 630
 631                 xsprintf(text, UID_FMT, geteuid());
 632
 633                 l = strlen(text);
 634                 b->auth_buffer = hexmem(text, l);
 635         }
 636
 637         if (!b->auth_buffer)
 638                 return -ENOMEM;
 639
 640         if (b->accept_fd)
 641                 auth_suffix = "\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n";
 642         else
 643                 auth_suffix = "\r\nBEGIN\r\n";
 644
 645         b->auth_iovec[0].iov_base = (void*) auth_prefix;
 646         b->auth_iovec[0].iov_len = 1 + strlen(auth_prefix + 1);
 647         b->auth_iovec[1].iov_base = (void*) b->auth_buffer;
 648         b->auth_iovec[1].iov_len = l * 2;
 649         b->auth_iovec[2].iov_base = (void*) auth_suffix;
 650         b->auth_iovec[2].iov_len = strlen(auth_suffix);
 651
 652         return bus_socket_write_auth(b);
 653 }
 654
 655 int bus_socket_start_auth(sd_bus *b) {
 656         assert(b);
 657
 658         bus_get_peercred(b);
 659
 660         bus_set_state(b, BUS_AUTHENTICATING);
 661         b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_AUTH_TIMEOUT;
 662
 663         if (sd_is_socket(b->input_fd, AF_UNIX, 0, 0) <= 0)
 664                 b->accept_fd = false;
 665
 666         if (b->output_fd != b->input_fd)
 667                 if (sd_is_socket(b->output_fd, AF_UNIX, 0, 0) <= 0)
 668                         b->accept_fd = false;
 669
 670         if (b->is_server)
 671                 return bus_socket_read_auth(b);
 672         else
 673                 return bus_socket_start_auth_client(b);
 674 }
 675
 676 static int bus_socket_inotify_setup(sd_bus *b) {
 677         _cleanup_free_ int *new_watches = NULL;
 678         _cleanup_free_ char *absolute = NULL;
 679         size_t n_allocated = 0, n = 0, done = 0, i;
 680         unsigned max_follow = 32;
 681         const char *p;
 682         int wd, r;
 683
 684         assert(b);
 685         assert(b->watch_bind);
 686         assert(b->sockaddr.sa.sa_family == AF_UNIX);
 687         assert(b->sockaddr.un.sun_path[0] != 0);
 688
 689         /* Sets up an inotify fd in case watch_bind is enabled: wait until the configured AF_UNIX file system socket
 690          * appears before connecting to it. The implemented is pretty simplistic: we just subscribe to relevant changes
 691          * to all prefix components of the path, and every time we get an event for that we try to reconnect again,
 692          * without actually caring what precisely the event we got told us. If we still can't connect we re-subscribe
 693          * to all relevant changes of anything in the path, so that our watches include any possibly newly created path
 694          * components. */
 695
 696         if (b->inotify_fd < 0) {
 697                 b->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
 698                 if (b->inotify_fd < 0)
 699                         return -errno;
 700
 701                 b->inotify_fd = fd_move_above_stdio(b->inotify_fd);
 702         }
 703
 704         /* Make sure the path is NUL terminated */
 705         p = strndupa(b->sockaddr.un.sun_path, sizeof(b->sockaddr.un.sun_path));
 706
 707         /* Make sure the path is absolute */
 708         r = path_make_absolute_cwd(p, &absolute);
 709         if (r < 0)
 710                 goto fail;
 711
 712         /* Watch all parent directories, and don't mind any prefix that doesn't exist yet. For the innermost directory
 713          * that exists we want to know when files are created or moved into it. For all parents of it we just care if
 714          * they are removed or renamed. */
 715
 716         if (!GREEDY_REALLOC(new_watches, n_allocated, n + 1)) {
 717                 r = -ENOMEM;
 718                 goto fail;
 719         }
 720
 721         /* Start with the top-level directory, which is a bit simpler than the rest, since it can't be a symlink, and
 722          * always exists */
 723         wd = inotify_add_watch(b->inotify_fd, "/", IN_CREATE|IN_MOVED_TO);
 724         if (wd < 0) {
 725                 r = log_debug_errno(errno, "Failed to add inotify watch on /: %m");
 726                 goto fail;
 727         } else
 728                 new_watches[n++] = wd;
 729
 730         for (;;) {
 731                 _cleanup_free_ char *component = NULL, *prefix = NULL, *destination = NULL;
 732                 size_t n_slashes, n_component;
 733                 char *c = NULL;
 734
 735                 n_slashes = strspn(absolute + done, "/");
 736                 n_component = n_slashes + strcspn(absolute + done + n_slashes, "/");
 737
 738                 if (n_component == 0) /* The end */
 739                         break;
 740
 741                 component = strndup(absolute + done, n_component);
 742                 if (!component) {
 743                         r = -ENOMEM;
 744                         goto fail;
 745                 }
 746
 747                 /* A trailing slash? That's a directory, and not a socket then */
 748                 if (path_equal(component, "/")) {
 749                         r = -EISDIR;
 750                         goto fail;
 751                 }
 752
 753                 /* A single dot? Let's eat this up */
 754                 if (path_equal(component, "/.")) {
 755                         done += n_component;
 756                         continue;
 757                 }
 758
 759                 prefix = strndup(absolute, done + n_component);
 760                 if (!prefix) {
 761                         r = -ENOMEM;
 762                         goto fail;
 763                 }
 764
 765                 if (!GREEDY_REALLOC(new_watches, n_allocated, n + 1)) {
 766                         r = -ENOMEM;
 767                         goto fail;
 768                 }
 769
 770                 wd = inotify_add_watch(b->inotify_fd, prefix, IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO|IN_DONT_FOLLOW);
 771                 log_debug("Added inotify watch for %s on bus %s: %i", prefix, strna(b->description), wd);
 772
 773                 if (wd < 0) {
 774                         if (IN_SET(errno, ENOENT, ELOOP))
 775                                 break; /* This component doesn't exist yet, or the path contains a cyclic symlink right now */
 776
 777                         r = log_debug_errno(errno, "Failed to add inotify watch on %s: %m", empty_to_root(prefix));
 778                         goto fail;
 779                 } else
 780                         new_watches[n++] = wd;
 781
 782                 /* Check if this is possibly a symlink. If so, let's follow it and watch it too. */
 783                 r = readlink_malloc(prefix, &destination);
 784                 if (r == -EINVAL) { /* not a symlink */
 785                         done += n_component;
 786                         continue;
 787                 }
 788                 if (r < 0)
 789                         goto fail;
 790
 791                 if (isempty(destination)) { /* Empty symlink target? Yuck! */
 792                         r = -EINVAL;
 793                         goto fail;
 794                 }
 795
 796                 if (max_follow <= 0) { /* Let's make sure we don't follow symlinks forever */
 797                         r = -ELOOP;
 798                         goto fail;
 799                 }
 800
 801                 if (path_is_absolute(destination)) {
 802                         /* For absolute symlinks we build the new path and start anew */
 803                         c = strjoin(destination, absolute + done + n_component);
 804                         done = 0;
 805                 } else {
 806                         _cleanup_free_ char *t = NULL;
 807
 808                         /* For relative symlinks we replace the last component, and try again */
 809                         t = strndup(absolute, done);
 810                         if (!t)
 811                                 return -ENOMEM;
 812
 813                         c = strjoin(t, "/", destination, absolute + done + n_component);
 814                 }
 815                 if (!c) {
 816                         r = -ENOMEM;
 817                         goto fail;
 818                 }
 819
 820                 free(absolute);
 821                 absolute = c;
 822
 823                 max_follow--;
 824         }
 825
 826         /* And now, let's remove all watches from the previous iteration we don't need anymore */
 827         for (i = 0; i < b->n_inotify_watches; i++) {
 828                 bool found = false;
 829                 size_t j;
 830
 831                 for (j = 0; j < n; j++)
 832                         if (new_watches[j] == b->inotify_watches[i]) {
 833                                 found = true;
 834                                 break;
 835                         }
 836
 837                 if (found)
 838                         continue;
 839
 840                 (void) inotify_rm_watch(b->inotify_fd, b->inotify_watches[i]);
 841         }
 842
 843         free_and_replace(b->inotify_watches, new_watches);
 844         b->n_inotify_watches = n;
 845
 846         return 0;
 847
 848 fail:
 849         bus_close_inotify_fd(b);
 850         return r;
 851 }
 852
 853 int bus_socket_connect(sd_bus *b) {
 854         bool inotify_done = false;
 855         int r;
 856
 857         assert(b);
 858
 859         for (;;) {
 860                 assert(b->input_fd < 0);
 861                 assert(b->output_fd < 0);
 862                 assert(b->sockaddr.sa.sa_family != AF_UNSPEC);
 863
 864                 b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 865                 if (b->input_fd < 0)
 866                         return -errno;
 867
 868                 b->input_fd = fd_move_above_stdio(b->input_fd);
 869
 870                 b->output_fd = b->input_fd;
 871                 bus_socket_setup(b);
 872
 873                 if (connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size) < 0) {
 874                         if (errno == EINPROGRESS) {
 875
 876                                 /* If we have any inotify watches open, close them now, we don't need them anymore, as
 877                                  * we have successfully initiated a connection */
 878                                 bus_close_inotify_fd(b);
 879
 880                                 /* Note that very likely we are already in BUS_OPENING state here, as we enter it when
 881                                  * we start parsing the address string. The only reason we set the state explicitly
 882                                  * here, is to undo BUS_WATCH_BIND, in case we did the inotify magic. */
 883                                 bus_set_state(b, BUS_OPENING);
 884                                 return 1;
 885                         }
 886
 887                         if (IN_SET(errno, ENOENT, ECONNREFUSED) &&  /* ENOENT → unix socket doesn't exist at all; ECONNREFUSED → unix socket stale */
 888                             b->watch_bind &&
 889                             b->sockaddr.sa.sa_family == AF_UNIX &&
 890                             b->sockaddr.un.sun_path[0] != 0) {
 891
 892                                 /* This connection attempt failed, let's release the socket for now, and start with a
 893                                  * fresh one when reconnecting. */
 894                                 bus_close_io_fds(b);
 895
 896                                 if (inotify_done) {
 897                                         /* inotify set up already, don't do it again, just return now, and remember
 898                                          * that we are waiting for inotify events now. */
 899                                         bus_set_state(b, BUS_WATCH_BIND);
 900                                         return 1;
 901                                 }
 902
 903                                 /* This is a file system socket, and the inotify logic is enabled. Let's create the necessary inotify fd. */
 904                                 r = bus_socket_inotify_setup(b);
 905                                 if (r < 0)
 906                                         return r;
 907
 908                                 /* Let's now try to connect a second time, because in theory there's otherwise a race
 909                                  * here: the socket might have been created in the time between our first connect() and
 910                                  * the time we set up the inotify logic. But let's remember that we set up inotify now,
 911                                  * so that we don't do the connect() more than twice. */
 912                                 inotify_done = true;
 913
 914                         } else
 915                                 return -errno;
 916                 } else
 917                         break;
 918         }
 919
 920         /* Yay, established, we don't need no inotify anymore! */
 921         bus_close_inotify_fd(b);
 922
 923         return bus_socket_start_auth(b);
 924 }
 925
 926 int bus_socket_exec(sd_bus *b) {
 927         int s[2], r;
 928
 929         assert(b);
 930         assert(b->input_fd < 0);
 931         assert(b->output_fd < 0);
 932         assert(b->exec_path);
 933         assert(b->busexec_pid == 0);
 934
 935         r = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s);
 936         if (r < 0)
 937                 return -errno;
 938
 939         r = safe_fork_full("(sd-busexec)", s+1, 1, FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS, &b->busexec_pid);
 940         if (r < 0) {
 941                 safe_close_pair(s);
 942                 return r;
 943         }
 944         if (r == 0) {
 945                 /* Child */
 946
 947                 if (rearrange_stdio(s[1], s[1], STDERR_FILENO) < 0)
 948                         _exit(EXIT_FAILURE);
 949
 950                 if (b->exec_argv)
 951                         execvp(b->exec_path, b->exec_argv);
 952                 else {
 953                         const char *argv[] = { b->exec_path, NULL };
 954                         execvp(b->exec_path, (char**) argv);
 955                 }
 956
 957                 _exit(EXIT_FAILURE);
 958         }
 959
 960         safe_close(s[1]);
 961         b->output_fd = b->input_fd = fd_move_above_stdio(s[0]);
 962
 963         bus_socket_setup(b);
 964
 965         return bus_socket_start_auth(b);
 966 }
 967
 968 int bus_socket_take_fd(sd_bus *b) {
 969         assert(b);
 970
 971         bus_socket_setup(b);
 972
 973         return bus_socket_start_auth(b);
 974 }
 975
 976 int bus_socket_write_message(sd_bus *bus, sd_bus_message *m, size_t *idx) {
 977         struct iovec *iov;
 978         ssize_t k;
 979         size_t n;
 980         unsigned j;
 981         int r;
 982
 983         assert(bus);
 984         assert(m);
 985         assert(idx);
 986         assert(IN_SET(bus->state, BUS_RUNNING, BUS_HELLO));
 987
 988         if (*idx >= BUS_MESSAGE_SIZE(m))
 989                 return 0;
 990
 991         r = bus_message_setup_iovec(m);
 992         if (r < 0)
 993                 return r;
 994
 995         n = m->n_iovec * sizeof(struct iovec);
 996         iov = alloca(n);
 997         memcpy_safe(iov, m->iovec, n);
 998
 999         j = 0;
1000         iovec_advance(iov, &j, *idx);
1001
1002         if (bus->prefer_writev)
1003                 k = writev(bus->output_fd, iov, m->n_iovec);
1004         else {
1005                 struct msghdr mh = {
1006                         .msg_iov = iov,
1007                         .msg_iovlen = m->n_iovec,
1008                 };
1009
1010                 if (m->n_fds > 0 && *idx == 0) {
1011                         struct cmsghdr *control;
1012
1013                         mh.msg_control = control = alloca(CMSG_SPACE(sizeof(int) * m->n_fds));
1014                         mh.msg_controllen = control->cmsg_len = CMSG_LEN(sizeof(int) * m->n_fds);
1015                         control->cmsg_level = SOL_SOCKET;
1016                         control->cmsg_type = SCM_RIGHTS;
1017                         memcpy(CMSG_DATA(control), m->fds, sizeof(int) * m->n_fds);
1018                 }
1019
1020                 k = sendmsg(bus->output_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
1021                 if (k < 0 && errno == ENOTSOCK) {
1022                         bus->prefer_writev = true;
1023                         k = writev(bus->output_fd, iov, m->n_iovec);
1024                 }
1025         }
1026
1027         if (k < 0)
1028                 return errno == EAGAIN ? 0 : -errno;
1029
1030         *idx += (size_t) k;
1031         return 1;
1032 }
1033
1034 static int bus_socket_read_message_need(sd_bus *bus, size_t *need) {
1035         uint32_t a, b;
1036         uint8_t e;
1037         uint64_t sum;
1038
1039         assert(bus);
1040         assert(need);
1041         assert(IN_SET(bus->state, BUS_RUNNING, BUS_HELLO));
1042
1043         if (bus->rbuffer_size < sizeof(struct bus_header)) {
1044                 *need = sizeof(struct bus_header) + 8;
1045
1046                 /* Minimum message size:
1047                  *
1048                  * Header +
1049                  *
1050                  *  Method Call: +2 string headers
1051                  *       Signal: +3 string headers
1052                  * Method Error: +1 string headers
1053                  *               +1 uint32 headers
1054                  * Method Reply: +1 uint32 headers
1055                  *
1056                  * A string header is at least 9 bytes
1057                  * A uint32 header is at least 8 bytes
1058                  *
1059                  * Hence the minimum message size of a valid message
1060                  * is header + 8 bytes */
1061
1062                 return 0;
1063         }
1064
1065         a = ((const uint32_t*) bus->rbuffer)[1];
1066         b = ((const uint32_t*) bus->rbuffer)[3];
1067
1068         e = ((const uint8_t*) bus->rbuffer)[0];
1069         if (e == BUS_LITTLE_ENDIAN) {
1070                 a = le32toh(a);
1071                 b = le32toh(b);
1072         } else if (e == BUS_BIG_ENDIAN) {
1073                 a = be32toh(a);
1074                 b = be32toh(b);
1075         } else
1076                 return -EBADMSG;
1077
1078         sum = (uint64_t) sizeof(struct bus_header) + (uint64_t) ALIGN_TO(b, 8) + (uint64_t) a;
1079         if (sum >= BUS_MESSAGE_SIZE_MAX)
1080                 return -ENOBUFS;
1081
1082         *need = (size_t) sum;
1083         return 0;
1084 }
1085
1086 static int bus_socket_make_message(sd_bus *bus, size_t size) {
1087         sd_bus_message *t;
1088         void *b;
1089         int r;
1090
1091         assert(bus);
1092         assert(bus->rbuffer_size >= size);
1093         assert(IN_SET(bus->state, BUS_RUNNING, BUS_HELLO));
1094
1095         r = bus_rqueue_make_room(bus);
1096         if (r < 0)
1097                 return r;
1098
1099         if (bus->rbuffer_size > size) {
1100                 b = memdup((const uint8_t*) bus->rbuffer + size,
1101                            bus->rbuffer_size - size);
1102                 if (!b)
1103                         return -ENOMEM;
1104         } else
1105                 b = NULL;
1106
1107         r = bus_message_from_malloc(bus,
1108                                     bus->rbuffer, size,
1109                                     bus->fds, bus->n_fds,
1110                                     NULL,
1111                                     &t);
1112         if (r < 0) {
1113                 free(b);
1114                 return r;
1115         }
1116
1117         bus->rbuffer = b;
1118         bus->rbuffer_size -= size;
1119
1120         bus->fds = NULL;
1121         bus->n_fds = 0;
1122
1123         bus->rqueue[bus->rqueue_size++] = t;
1124
1125         return 1;
1126 }
1127
1128 int bus_socket_read_message(sd_bus *bus) {
1129         struct msghdr mh;
1130         struct iovec iov = {};
1131         ssize_t k;
1132         size_t need;
1133         int r;
1134         void *b;
1135         union {
1136                 struct cmsghdr cmsghdr;
1137                 uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)];
1138         } control;
1139         bool handle_cmsg = false;
1140
1141         assert(bus);
1142         assert(IN_SET(bus->state, BUS_RUNNING, BUS_HELLO));
1143
1144         r = bus_socket_read_message_need(bus, &need);
1145         if (r < 0)
1146                 return r;
1147
1148         if (bus->rbuffer_size >= need)
1149                 return bus_socket_make_message(bus, need);
1150
1151         b = realloc(bus->rbuffer, need);
1152         if (!b)
1153                 return -ENOMEM;
1154
1155         bus->rbuffer = b;
1156
1157         iov.iov_base = (uint8_t*) bus->rbuffer + bus->rbuffer_size;
1158         iov.iov_len = need - bus->rbuffer_size;
1159
1160         if (bus->prefer_readv)
1161                 k = readv(bus->input_fd, &iov, 1);
1162         else {
1163                 zero(mh);
1164                 mh.msg_iov = &iov;
1165                 mh.msg_iovlen = 1;
1166                 mh.msg_control = &control;
1167                 mh.msg_controllen = sizeof(control);
1168
1169                 k = recvmsg(bus->input_fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
1170                 if (k < 0 && errno == ENOTSOCK) {
1171                         bus->prefer_readv = true;
1172                         k = readv(bus->input_fd, &iov, 1);
1173                 } else
1174                         handle_cmsg = true;
1175         }
1176         if (k < 0)
1177                 return errno == EAGAIN ? 0 : -errno;
1178         if (k == 0)
1179                 return -ECONNRESET;
1180
1181         bus->rbuffer_size += k;
1182
1183         if (handle_cmsg) {
1184                 struct cmsghdr *cmsg;
1185
1186                 CMSG_FOREACH(cmsg, &mh)
1187                         if (cmsg->cmsg_level == SOL_SOCKET &&
1188                             cmsg->cmsg_type == SCM_RIGHTS) {
1189                                 int n, *f, i;
1190
1191                                 n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
1192
1193                                 if (!bus->can_fds) {
1194                                         /* Whut? We received fds but this
1195                                          * isn't actually enabled? Close them,
1196                                          * and fail */
1197
1198                                         close_many((int*) CMSG_DATA(cmsg), n);
1199                                         return -EIO;
1200                                 }
1201
1202                                 f = reallocarray(bus->fds, bus->n_fds + n, sizeof(int));
1203                                 if (!f) {
1204                                         close_many((int*) CMSG_DATA(cmsg), n);
1205                                         return -ENOMEM;
1206                                 }
1207
1208                                 for (i = 0; i < n; i++)
1209                                         f[bus->n_fds++] = fd_move_above_stdio(((int*) CMSG_DATA(cmsg))[i]);
1210                                 bus->fds = f;
1211                         } else
1212                                 log_debug("Got unexpected auxiliary data with level=%d and type=%d",
1213                                           cmsg->cmsg_level, cmsg->cmsg_type);
1214         }
1215
1216         r = bus_socket_read_message_need(bus, &need);
1217         if (r < 0)
1218                 return r;
1219
1220         if (bus->rbuffer_size >= need)
1221                 return bus_socket_make_message(bus, need);
1222
1223         return 1;
1224 }
1225
1226 int bus_socket_process_opening(sd_bus *b) {
1227         int error = 0;
1228         socklen_t slen = sizeof(error);
1229         struct pollfd p = {
1230                 .fd = b->output_fd,
1231                 .events = POLLOUT,
1232         };
1233         int r;
1234
1235         assert(b->state == BUS_OPENING);
1236
1237         r = poll(&p, 1, 0);
1238         if (r < 0)
1239                 return -errno;
1240
1241         if (!(p.revents & (POLLOUT|POLLERR|POLLHUP)))
1242                 return 0;
1243
1244         r = getsockopt(b->output_fd, SOL_SOCKET, SO_ERROR, &error, &slen);
1245         if (r < 0)
1246                 b->last_connect_error = errno;
1247         else if (error != 0)
1248                 b->last_connect_error = error;
1249         else if (p.revents & (POLLERR|POLLHUP))
1250                 b->last_connect_error = ECONNREFUSED;
1251         else
1252                 return bus_socket_start_auth(b);
1253
1254         return bus_next_address(b);
1255 }
1256
1257 int bus_socket_process_authenticating(sd_bus *b) {
1258         int r;
1259
1260         assert(b);
1261         assert(b->state == BUS_AUTHENTICATING);
1262
1263         if (now(CLOCK_MONOTONIC) >= b->auth_timeout)
1264                 return -ETIMEDOUT;
1265
1266         r = bus_socket_write_auth(b);
1267         if (r != 0)
1268                 return r;
1269
1270         return bus_socket_read_auth(b);
1271 }
1272
1273 int bus_socket_process_watch_bind(sd_bus *b) {
1274         int r, q;
1275
1276         assert(b);
1277         assert(b->state == BUS_WATCH_BIND);
1278         assert(b->inotify_fd >= 0);
1279
1280         r = flush_fd(b->inotify_fd);
1281         if (r <= 0)
1282                 return r;
1283
1284         log_debug("Got inotify event on bus %s.", strna(b->description));
1285
1286         /* We flushed events out of the inotify fd. In that case, maybe the socket is valid now? Let's try to connect
1287          * to it again */
1288
1289         r = bus_socket_connect(b);
1290         if (r < 0)
1291                 return r;
1292
1293         q = bus_attach_io_events(b);
1294         if (q < 0)
1295                 return q;
1296
1297         q = bus_attach_inotify_event(b);
1298         if (q < 0)
1299                 return q;
1300
1301         return r;
1302 }