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