src/main.c

   1 /*
   2  * cgi-io - LuCI non-RPC helper
   3  *
   4  *   Copyright (C) 2013 Jo-Philipp Wich <jo@mein.io>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #define _GNU_SOURCE /* splice(), SPLICE_F_MORE */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <stdbool.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <ctype.h>
  29 #include <sys/stat.h>
  30 #include <sys/wait.h>
  31 #include <sys/sendfile.h>
  32 #include <sys/ioctl.h>
  33 #include <linux/fs.h>
  34
  35 #include <libubus.h>
  36 #include <libubox/blobmsg.h>
  37
  38 #include "multipart_parser.h"
  39
  40 #define READ_BLOCK 4096
  41
  42 enum part {
  43         PART_UNKNOWN,
  44         PART_SESSIONID,
  45         PART_FILENAME,
  46         PART_FILEMODE,
  47         PART_FILEDATA
  48 };
  49
  50 const char *parts[] = {
  51         "(bug)",
  52         "sessionid",
  53         "filename",
  54         "filemode",
  55         "filedata",
  56 };
  57
  58 struct state
  59 {
  60         bool is_content_disposition;
  61         enum part parttype;
  62         char *sessionid;
  63         char *filename;
  64         bool filedata;
  65         int filemode;
  66         int filefd;
  67         int tempfd;
  68 };
  69
  70 enum {
  71         SES_ACCESS,
  72         __SES_MAX,
  73 };
  74
  75 static const struct blobmsg_policy ses_policy[__SES_MAX] = {
  76         [SES_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_BOOL },
  77 };
  78
  79
  80 static struct state st;
  81
  82 static void
  83 session_access_cb(struct ubus_request *req, int type, struct blob_attr *msg)
  84 {
  85         struct blob_attr *tb[__SES_MAX];
  86         bool *allow = (bool *)req->priv;
  87
  88         if (!msg)
  89                 return;
  90
  91         blobmsg_parse(ses_policy, __SES_MAX, tb, blob_data(msg), blob_len(msg));
  92
  93         if (tb[SES_ACCESS])
  94                 *allow = blobmsg_get_bool(tb[SES_ACCESS]);
  95 }
  96
  97 static bool
  98 session_access(const char *sid, const char *scope, const char *obj, const char *func)
  99 {
 100         uint32_t id;
 101         bool allow = false;
 102         struct ubus_context *ctx;
 103         static struct blob_buf req;
 104
 105         ctx = ubus_connect(NULL);
 106
 107         if (!ctx || ubus_lookup_id(ctx, "session", &id))
 108                 goto out;
 109
 110         blob_buf_init(&req, 0);
 111         blobmsg_add_string(&req, "ubus_rpc_session", sid);
 112         blobmsg_add_string(&req, "scope", scope);
 113         blobmsg_add_string(&req, "object", obj);
 114         blobmsg_add_string(&req, "function", func);
 115
 116         ubus_invoke(ctx, id, "access", req.head, session_access_cb, &allow, 500);
 117
 118 out:
 119         if (ctx)
 120                 ubus_free(ctx);
 121
 122         return allow;
 123 }
 124
 125 static char *
 126 checksum(const char *applet, size_t sumlen, const char *file)
 127 {
 128         pid_t pid;
 129         int fds[2];
 130         static char chksum[65];
 131
 132         if (pipe(fds))
 133                 return NULL;
 134
 135         switch ((pid = fork()))
 136         {
 137         case -1:
 138                 return NULL;
 139
 140         case 0:
 141                 uloop_done();
 142
 143                 dup2(fds[1], 1);
 144
 145                 close(0);
 146                 close(2);
 147                 close(fds[0]);
 148                 close(fds[1]);
 149
 150                 if (execl("/bin/busybox", "/bin/busybox", applet, file, NULL))
 151                         return NULL;
 152
 153                 break;
 154
 155         default:
 156                 memset(chksum, 0, sizeof(chksum));
 157                 read(fds[0], chksum, sumlen);
 158                 waitpid(pid, NULL, 0);
 159                 close(fds[0]);
 160                 close(fds[1]);
 161         }
 162
 163         return chksum;
 164 }
 165
 166 static char *
 167 datadup(const void *in, size_t len)
 168 {
 169         char *out = malloc(len + 1);
 170
 171         if (!out)
 172                 return NULL;
 173
 174         memcpy(out, in, len);
 175
 176         *(out + len) = 0;
 177
 178         return out;
 179 }
 180
 181 static bool
 182 urldecode(char *buf)
 183 {
 184         char *c, *p;
 185
 186         if (!buf || !*buf)
 187                 return true;
 188
 189 #define hex(x) \
 190         (((x) <= '9') ? ((x) - '0') : \
 191                 (((x) <= 'F') ? ((x) - 'A' + 10) : \
 192                         ((x) - 'a' + 10)))
 193
 194         for (c = p = buf; *p; c++)
 195         {
 196                 if (*p == '%')
 197                 {
 198                         if (!isxdigit(*(p + 1)) || !isxdigit(*(p + 2)))
 199                                 return false;
 200
 201                         *c = (char)(16 * hex(*(p + 1)) + hex(*(p + 2)));
 202
 203                         p += 3;
 204                 }
 205                 else if (*p == '+')
 206                 {
 207                         *c = ' ';
 208                         p++;
 209                 }
 210                 else
 211                 {
 212                         *c = *p++;
 213                 }
 214         }
 215
 216         *c = 0;
 217
 218         return true;
 219 }
 220
 221 static bool
 222 postdecode(char **fields, int n_fields)
 223 {
 224         char *p;
 225         const char *var;
 226         static char buf[1024];
 227         int i, len, field, found = 0;
 228
 229         var = getenv("CONTENT_TYPE");
 230
 231         if (!var || strncmp(var, "application/x-www-form-urlencoded", 33))
 232                 return false;
 233
 234         memset(buf, 0, sizeof(buf));
 235
 236         if ((len = read(0, buf, sizeof(buf) - 1)) > 0)
 237         {
 238                 for (p = buf, i = 0; i <= len; i++)
 239                 {
 240                         if (buf[i] == '=')
 241                         {
 242                                 buf[i] = 0;
 243
 244                                 for (field = 0; field < (n_fields * 2); field += 2)
 245                                 {
 246                                         if (!strcmp(p, fields[field]))
 247                                         {
 248                                                 fields[field + 1] = buf + i + 1;
 249                                                 found++;
 250                                         }
 251                                 }
 252                         }
 253                         else if (buf[i] == '&' || buf[i] == '\0')
 254                         {
 255                                 buf[i] = 0;
 256
 257                                 if (found >= n_fields)
 258                                         break;
 259
 260                                 p = buf + i + 1;
 261                         }
 262                 }
 263         }
 264
 265         for (field = 0; field < (n_fields * 2); field += 2)
 266                 if (!urldecode(fields[field + 1]))
 267                         return false;
 268
 269         return (found >= n_fields);
 270 }
 271
 272 static char *
 273 canonicalize_path(const char *path, size_t len)
 274 {
 275         char *canonpath, *cp;
 276         const char *p, *e;
 277
 278         if (path == NULL || *path == '\0')
 279                 return NULL;
 280
 281         canonpath = datadup(path, len);
 282
 283         if (canonpath == NULL)
 284                 return NULL;
 285
 286         /* normalize */
 287         for (cp = canonpath, p = path, e = path + len; p < e; ) {
 288                 if (*p != '/')
 289                         goto next;
 290
 291                 /* skip repeating / */
 292                 if ((p + 1 < e) && (p[1] == '/')) {
 293                         p++;
 294                         continue;
 295                 }
 296
 297                 /* /./ or /../ */
 298                 if ((p + 1 < e) && (p[1] == '.')) {
 299                         /* skip /./ */
 300                         if ((p + 2 >= e) || (p[2] == '/')) {
 301                                 p += 2;
 302                                 continue;
 303                         }
 304
 305                         /* collapse /x/../ */
 306                         if ((p + 2 < e) && (p[2] == '.') && ((p + 3 >= e) || (p[3] == '/'))) {
 307                                 while ((cp > canonpath) && (*--cp != '/'))
 308                                         ;
 309
 310                                 p += 3;
 311                                 continue;
 312                         }
 313                 }
 314
 315 next:
 316                 *cp++ = *p++;
 317         }
 318
 319         /* remove trailing slash if not root / */
 320         if ((cp > canonpath + 1) && (cp[-1] == '/'))
 321                 cp--;
 322         else if (cp == canonpath)
 323                 *cp++ = '/';
 324
 325         *cp = '\0';
 326
 327         return canonpath;
 328 }
 329
 330 static int
 331 response(bool success, const char *message)
 332 {
 333         char *chksum;
 334         struct stat s;
 335
 336         printf("Status: 200 OK\r\n");
 337         printf("Content-Type: text/plain\r\n\r\n{\n");
 338
 339         if (success)
 340         {
 341                 if (!stat(st.filename, &s))
 342                         printf("\t\"size\": %u,\n", (unsigned int)s.st_size);
 343                 else
 344                         printf("\t\"size\": null,\n");
 345
 346                 chksum = checksum("md5sum", 32, st.filename);
 347                 printf("\t\"checksum\": %s%s%s,\n",
 348                         chksum ? "\"" : "",
 349                         chksum ? chksum : "null",
 350                         chksum ? "\"" : "");
 351
 352                 chksum = checksum("sha256sum", 64, st.filename);
 353                 printf("\t\"sha256sum\": %s%s%s\n",
 354                         chksum ? "\"" : "",
 355                         chksum ? chksum : "null",
 356                         chksum ? "\"" : "");
 357         }
 358         else
 359         {
 360                 if (message)
 361                         printf("\t\"message\": \"%s\",\n", message);
 362
 363                 printf("\t\"failure\": [ %u, \"%s\" ]\n", errno, strerror(errno));
 364
 365                 if (st.filefd > -1)
 366                         unlink(st.filename);
 367         }
 368
 369         printf("}\n");
 370
 371         return -1;
 372 }
 373
 374 static int
 375 failure(int code, int e, const char *message)
 376 {
 377         printf("Status: %d %s\r\n", code, message);
 378         printf("Content-Type: text/plain\r\n\r\n");
 379         printf("%s", message);
 380
 381         if (e)
 382                 printf(": %s", strerror(e));
 383
 384         printf("\n");
 385
 386         return -1;
 387 }
 388
 389 static int
 390 filecopy(void)
 391 {
 392         int len;
 393         char buf[READ_BLOCK];
 394
 395         if (!st.filedata)
 396         {
 397                 close(st.tempfd);
 398                 errno = EINVAL;
 399                 return response(false, "No file data received");
 400         }
 401
 402         if (lseek(st.tempfd, 0, SEEK_SET) < 0)
 403         {
 404                 close(st.tempfd);
 405                 return response(false, "Failed to rewind temp file");
 406         }
 407
 408         st.filefd = open(st.filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
 409
 410         if (st.filefd < 0)
 411         {
 412                 close(st.tempfd);
 413                 return response(false, "Failed to open target file");
 414         }
 415
 416         while ((len = read(st.tempfd, buf, sizeof(buf))) > 0)
 417         {
 418                 if (write(st.filefd, buf, len) != len)
 419                 {
 420                         close(st.tempfd);
 421                         close(st.filefd);
 422                         return response(false, "I/O failure while writing target file");
 423                 }
 424         }
 425
 426         close(st.tempfd);
 427         close(st.filefd);
 428
 429         if (chmod(st.filename, st.filemode))
 430                 return response(false, "Failed to chmod target file");
 431
 432         return 0;
 433 }
 434
 435 static int
 436 header_field(multipart_parser *p, const char *data, size_t len)
 437 {
 438         st.is_content_disposition = !strncasecmp(data, "Content-Disposition", len);
 439         return 0;
 440 }
 441
 442 static int
 443 header_value(multipart_parser *p, const char *data, size_t len)
 444 {
 445         int i, j;
 446
 447         if (!st.is_content_disposition)
 448                 return 0;
 449
 450         if (len < 10 || strncasecmp(data, "form-data", 9))
 451                 return 0;
 452
 453         for (data += 9, len -= 9; *data == ' ' || *data == ';'; data++, len--);
 454
 455         if (len < 8 || strncasecmp(data, "name=\"", 6))
 456                 return 0;
 457
 458         for (data += 6, len -= 6, i = 0; i <= len; i++)
 459         {
 460                 if (*(data + i) != '"')
 461                         continue;
 462
 463                 for (j = 1; j < sizeof(parts) / sizeof(parts[0]); j++)
 464                         if (!strncmp(data, parts[j], i))
 465                                 st.parttype = j;
 466
 467                 break;
 468         }
 469
 470         return 0;
 471 }
 472
 473 static int
 474 data_begin_cb(multipart_parser *p)
 475 {
 476         char tmpname[24] = "/tmp/luci-upload.XXXXXX";
 477
 478         if (st.parttype == PART_FILEDATA)
 479         {
 480                 if (!st.sessionid)
 481                         return response(false, "File data without session");
 482
 483                 if (!st.filename)
 484                         return response(false, "File data without name");
 485
 486                 if (!session_access(st.sessionid, "file", st.filename, "write"))
 487                         return response(false, "Access to path denied by ACL");
 488
 489                 st.tempfd = mkstemp(tmpname);
 490
 491                 if (st.tempfd < 0)
 492                         return response(false, "Failed to create temporary file");
 493
 494                 unlink(tmpname);
 495         }
 496
 497         return 0;
 498 }
 499
 500 static int
 501 data_cb(multipart_parser *p, const char *data, size_t len)
 502 {
 503         switch (st.parttype)
 504         {
 505         case PART_SESSIONID:
 506                 st.sessionid = datadup(data, len);
 507                 break;
 508
 509         case PART_FILENAME:
 510                 st.filename = canonicalize_path(data, len);
 511                 break;
 512
 513         case PART_FILEMODE:
 514                 st.filemode = strtoul(data, NULL, 8);
 515                 break;
 516
 517         case PART_FILEDATA:
 518                 if (write(st.tempfd, data, len) != len)
 519                 {
 520                         close(st.tempfd);
 521                         return response(false, "I/O failure while writing temporary file");
 522                 }
 523
 524                 if (!st.filedata)
 525                         st.filedata = !!len;
 526
 527                 break;
 528
 529         default:
 530                 break;
 531         }
 532
 533         return 0;
 534 }
 535
 536 static int
 537 data_end_cb(multipart_parser *p)
 538 {
 539         if (st.parttype == PART_SESSIONID)
 540         {
 541                 if (!session_access(st.sessionid, "cgi-io", "upload", "write"))
 542                 {
 543                         errno = EPERM;
 544                         return response(false, "Upload permission denied");
 545                 }
 546         }
 547         else if (st.parttype == PART_FILEDATA)
 548         {
 549                 if (st.tempfd < 0)
 550                         return response(false, "Internal program failure");
 551
 552 #if 0
 553                 /* prepare directory */
 554                 for (ptr = st.filename; *ptr; ptr++)
 555                 {
 556                         if (*ptr == '/')
 557                         {
 558                                 *ptr = 0;
 559
 560                                 if (mkdir(st.filename, 0755))
 561                                 {
 562                                         unlink(st.tmpname);
 563                                         return response(false, "Failed to create destination directory");
 564                                 }
 565
 566                                 *ptr = '/';
 567                         }
 568                 }
 569 #endif
 570
 571                 if (filecopy())
 572                         return -1;
 573
 574                 return response(true, NULL);
 575         }
 576
 577         st.parttype = PART_UNKNOWN;
 578         return 0;
 579 }
 580
 581 static multipart_parser *
 582 init_parser(void)
 583 {
 584         char *boundary;
 585         const char *var;
 586
 587         multipart_parser *p;
 588         static multipart_parser_settings s = {
 589                 .on_part_data        = data_cb,
 590                 .on_headers_complete = data_begin_cb,
 591                 .on_part_data_end    = data_end_cb,
 592                 .on_header_field     = header_field,
 593                 .on_header_value     = header_value
 594         };
 595
 596         var = getenv("CONTENT_TYPE");
 597
 598         if (!var || strncmp(var, "multipart/form-data;", 20))
 599                 return NULL;
 600
 601         for (var += 20; *var && *var != '='; var++);
 602
 603         if (*var++ != '=')
 604                 return NULL;
 605
 606         boundary = malloc(strlen(var) + 3);
 607
 608         if (!boundary)
 609                 return NULL;
 610
 611         strcpy(boundary, "--");
 612         strcpy(boundary + 2, var);
 613
 614         st.tempfd = -1;
 615         st.filefd = -1;
 616         st.filemode = 0600;
 617
 618         p = multipart_parser_init(boundary, &s);
 619
 620         free(boundary);
 621
 622         return p;
 623 }
 624
 625 static int
 626 main_upload(int argc, char *argv[])
 627 {
 628         int rem, len;
 629         bool done = false;
 630         char buf[READ_BLOCK];
 631         multipart_parser *p;
 632
 633         p = init_parser();
 634
 635         if (!p)
 636         {
 637                 errno = EINVAL;
 638                 return response(false, "Invalid request");
 639         }
 640
 641         while ((len = read(0, buf, sizeof(buf))) > 0)
 642         {
 643                 if (!done) {
 644                         rem = multipart_parser_execute(p, buf, len);
 645                         done = (rem < len);
 646                 }
 647         }
 648
 649         multipart_parser_free(p);
 650
 651         return 0;
 652 }
 653
 654 static int
 655 main_download(int argc, char **argv)
 656 {
 657         char *fields[] = { "sessionid", NULL, "path", NULL, "filename", NULL, "mimetype", NULL };
 658         unsigned long long size = 0;
 659         char *p, buf[READ_BLOCK];
 660         ssize_t len = 0;
 661         struct stat s;
 662         int rfd;
 663
 664         postdecode(fields, 4);
 665
 666         if (!fields[1] || !session_access(fields[1], "cgi-io", "download", "read"))
 667                 return failure(403, 0, "Download permission denied");
 668
 669         if (!fields[3] || !session_access(fields[1], "file", fields[3], "read"))
 670                 return failure(403, 0, "Access to path denied by ACL");
 671
 672         if (stat(fields[3], &s))
 673                 return failure(404, errno, "Failed to stat requested path");
 674
 675         if (!S_ISREG(s.st_mode) && !S_ISBLK(s.st_mode))
 676                 return failure(403, 0, "Requested path is not a regular file or block device");
 677
 678         for (p = fields[5]; p && *p; p++)
 679                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%-", *p))
 680                         return failure(400, 0, "Invalid characters in filename");
 681
 682         for (p = fields[7]; p && *p; p++)
 683                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 684                         return failure(400, 0, "Invalid characters in mimetype");
 685
 686         rfd = open(fields[3], O_RDONLY);
 687
 688         if (rfd < 0)
 689                 return failure(500, errno, "Failed to open requested path");
 690
 691         if (S_ISBLK(s.st_mode))
 692                 ioctl(rfd, BLKGETSIZE64, &size);
 693         else
 694                 size = (unsigned long long)s.st_size;
 695
 696         printf("Status: 200 OK\r\n");
 697         printf("Content-Type: %s\r\n", fields[7] ? fields[7] : "application/octet-stream");
 698
 699         if (fields[5])
 700                 printf("Content-Disposition: attachment; filename=\"%s\"\r\n", fields[5]);
 701
 702         printf("Content-Length: %llu\r\n\r\n", size);
 703         fflush(stdout);
 704
 705         while (size > 0) {
 706                 len = sendfile(1, rfd, NULL, size);
 707
 708                 if (len == -1) {
 709                         if (errno == ENOSYS || errno == EINVAL) {
 710                                 while ((len = read(rfd, buf, sizeof(buf))) > 0)
 711                                         fwrite(buf, len, 1, stdout);
 712
 713                                 fflush(stdout);
 714                                 break;
 715                         }
 716
 717                         if (errno == EINTR || errno == EAGAIN)
 718                                 continue;
 719                 }
 720
 721                 if (len <= 0)
 722                         break;
 723
 724                 size -= len;
 725         }
 726
 727         close(rfd);
 728
 729         return 0;
 730 }
 731
 732 static int
 733 main_backup(int argc, char **argv)
 734 {
 735         pid_t pid;
 736         time_t now;
 737         int len;
 738         int status;
 739         int fds[2];
 740         char datestr[16] = { 0 };
 741         char hostname[64] = { 0 };
 742         char *fields[] = { "sessionid", NULL };
 743
 744         if (!postdecode(fields, 1) || !session_access(fields[1], "cgi-io", "backup", "read"))
 745                 return failure(403, 0, "Backup permission denied");
 746
 747         if (pipe(fds))
 748                 return failure(500, errno, "Failed to spawn pipe");
 749
 750         switch ((pid = fork()))
 751         {
 752         case -1:
 753                 return failure(500, errno, "Failed to fork process");
 754
 755         case 0:
 756                 dup2(fds[1], 1);
 757
 758                 close(0);
 759                 close(2);
 760                 close(fds[0]);
 761                 close(fds[1]);
 762
 763                 chdir("/");
 764
 765                 execl("/sbin/sysupgrade", "/sbin/sysupgrade",
 766                       "--create-backup", "-", NULL);
 767
 768                 return -1;
 769
 770         default:
 771                 now = time(NULL);
 772                 strftime(datestr, sizeof(datestr) - 1, "%Y-%m-%d", localtime(&now));
 773
 774                 if (gethostname(hostname, sizeof(hostname) - 1))
 775                         sprintf(hostname, "OpenWrt");
 776
 777                 printf("Status: 200 OK\r\n");
 778                 printf("Content-Type: application/x-targz\r\n");
 779                 printf("Content-Disposition: attachment; "
 780                        "filename=\"backup-%s-%s.tar.gz\"\r\n\r\n", hostname, datestr);
 781
 782                 fflush(stdout);
 783
 784                 do {
 785                         len = splice(fds[0], NULL, 1, NULL, READ_BLOCK, SPLICE_F_MORE);
 786                 } while (len > 0);
 787
 788                 waitpid(pid, &status, 0);
 789
 790                 close(fds[0]);
 791                 close(fds[1]);
 792
 793                 return 0;
 794         }
 795 }
 796
 797 int main(int argc, char **argv)
 798 {
 799         if (strstr(argv[0], "cgi-upload"))
 800                 return main_upload(argc, argv);
 801         else if (strstr(argv[0], "cgi-download"))
 802                 return main_download(argc, argv);
 803         else if (strstr(argv[0], "cgi-backup"))
 804                 return main_backup(argc, argv);
 805
 806         return -1;
 807 }