net/cgi-io/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
  41 enum part {
  42         PART_UNKNOWN,
  43         PART_SESSIONID,
  44         PART_FILENAME,
  45         PART_FILEMODE,
  46         PART_FILEDATA
  47 };
  48
  49 const char *parts[] = {
  50         "(bug)",
  51         "sessionid",
  52         "filename",
  53         "filemode",
  54         "filedata",
  55 };
  56
  57 struct state
  58 {
  59         bool is_content_disposition;
  60         enum part parttype;
  61         char *sessionid;
  62         char *filename;
  63         bool filedata;
  64         int filemode;
  65         int filefd;
  66         int tempfd;
  67 };
  68
  69 enum {
  70         SES_ACCESS,
  71         __SES_MAX,
  72 };
  73
  74 static const struct blobmsg_policy ses_policy[__SES_MAX] = {
  75         [SES_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_BOOL },
  76 };
  77
  78
  79 static struct state st;
  80
  81 static void
  82 session_access_cb(struct ubus_request *req, int type, struct blob_attr *msg)
  83 {
  84         struct blob_attr *tb[__SES_MAX];
  85         bool *allow = (bool *)req->priv;
  86
  87         if (!msg)
  88                 return;
  89
  90         blobmsg_parse(ses_policy, __SES_MAX, tb, blob_data(msg), blob_len(msg));
  91
  92         if (tb[SES_ACCESS])
  93                 *allow = blobmsg_get_bool(tb[SES_ACCESS]);
  94 }
  95
  96 static bool
  97 session_access(const char *sid, const char *scope, const char *obj, const char *func)
  98 {
  99         uint32_t id;
 100         bool allow = false;
 101         struct ubus_context *ctx;
 102         static struct blob_buf req;
 103
 104         ctx = ubus_connect(NULL);
 105
 106         if (!ctx || ubus_lookup_id(ctx, "session", &id))
 107                 goto out;
 108
 109         blob_buf_init(&req, 0);
 110         blobmsg_add_string(&req, "ubus_rpc_session", sid);
 111         blobmsg_add_string(&req, "scope", scope);
 112         blobmsg_add_string(&req, "object", obj);
 113         blobmsg_add_string(&req, "function", func);
 114
 115         ubus_invoke(ctx, id, "access", req.head, session_access_cb, &allow, 500);
 116
 117 out:
 118         if (ctx)
 119                 ubus_free(ctx);
 120
 121         return allow;
 122 }
 123
 124 static char *
 125 checksum(const char *applet, size_t sumlen, const char *file)
 126 {
 127         pid_t pid;
 128         int fds[2];
 129         static char chksum[65];
 130
 131         if (pipe(fds))
 132                 return NULL;
 133
 134         switch ((pid = fork()))
 135         {
 136         case -1:
 137                 return NULL;
 138
 139         case 0:
 140                 uloop_done();
 141
 142                 dup2(fds[1], 1);
 143
 144                 close(0);
 145                 close(2);
 146                 close(fds[0]);
 147                 close(fds[1]);
 148
 149                 if (execl("/bin/busybox", "/bin/busybox", applet, file, NULL))
 150                         return NULL;
 151
 152                 break;
 153
 154         default:
 155                 memset(chksum, 0, sizeof(chksum));
 156                 read(fds[0], chksum, sumlen);
 157                 waitpid(pid, NULL, 0);
 158                 close(fds[0]);
 159                 close(fds[1]);
 160         }
 161
 162         return chksum;
 163 }
 164
 165 static char *
 166 datadup(const void *in, size_t len)
 167 {
 168         char *out = malloc(len + 1);
 169
 170         if (!out)
 171                 return NULL;
 172
 173         memcpy(out, in, len);
 174
 175         *(out + len) = 0;
 176
 177         return out;
 178 }
 179
 180 static bool
 181 urldecode(char *buf)
 182 {
 183         char *c, *p;
 184
 185         if (!buf || !*buf)
 186                 return true;
 187
 188 #define hex(x) \
 189         (((x) <= '9') ? ((x) - '0') : \
 190                 (((x) <= 'F') ? ((x) - 'A' + 10) : \
 191                         ((x) - 'a' + 10)))
 192
 193         for (c = p = buf; *p; c++)
 194         {
 195                 if (*p == '%')
 196                 {
 197                         if (!isxdigit(*(p + 1)) || !isxdigit(*(p + 2)))
 198                                 return false;
 199
 200                         *c = (char)(16 * hex(*(p + 1)) + hex(*(p + 2)));
 201
 202                         p += 3;
 203                 }
 204                 else if (*p == '+')
 205                 {
 206                         *c = ' ';
 207                         p++;
 208                 }
 209                 else
 210                 {
 211                         *c = *p++;
 212                 }
 213         }
 214
 215         *c = 0;
 216
 217         return true;
 218 }
 219
 220 static bool
 221 postdecode(char **fields, int n_fields)
 222 {
 223         char *p;
 224         const char *var;
 225         static char buf[1024];
 226         int i, len, field, found = 0;
 227
 228         var = getenv("CONTENT_TYPE");
 229
 230         if (!var || strncmp(var, "application/x-www-form-urlencoded", 33))
 231                 return false;
 232
 233         memset(buf, 0, sizeof(buf));
 234
 235         if ((len = read(0, buf, sizeof(buf) - 1)) > 0)
 236         {
 237                 for (p = buf, i = 0; i <= len; i++)
 238                 {
 239                         if (buf[i] == '=')
 240                         {
 241                                 buf[i] = 0;
 242
 243                                 for (field = 0; field < (n_fields * 2); field += 2)
 244                                 {
 245                                         if (!strcmp(p, fields[field]))
 246                                         {
 247                                                 fields[field + 1] = buf + i + 1;
 248                                                 found++;
 249                                         }
 250                                 }
 251                         }
 252                         else if (buf[i] == '&' || buf[i] == '\0')
 253                         {
 254                                 buf[i] = 0;
 255
 256                                 if (found >= n_fields)
 257                                         break;
 258
 259                                 p = buf + i + 1;
 260                         }
 261                 }
 262         }
 263
 264         for (field = 0; field < (n_fields * 2); field += 2)
 265                 if (!urldecode(fields[field + 1]))
 266                         return false;
 267
 268         return (found >= n_fields);
 269 }
 270
 271 static char *
 272 canonicalize_path(const char *path, size_t len)
 273 {
 274         char *canonpath, *cp;
 275         const char *p, *e;
 276
 277         if (path == NULL || *path == '\0')
 278                 return NULL;
 279
 280         canonpath = datadup(path, len);
 281
 282         if (canonpath == NULL)
 283                 return NULL;
 284
 285         /* normalize */
 286         for (cp = canonpath, p = path, e = path + len; p < e; ) {
 287                 if (*p != '/')
 288                         goto next;
 289
 290                 /* skip repeating / */
 291                 if ((p + 1 < e) && (p[1] == '/')) {
 292                         p++;
 293                         continue;
 294                 }
 295
 296                 /* /./ or /../ */
 297                 if ((p + 1 < e) && (p[1] == '.')) {
 298                         /* skip /./ */
 299                         if ((p + 2 >= e) || (p[2] == '/')) {
 300                                 p += 2;
 301                                 continue;
 302                         }
 303
 304                         /* collapse /x/../ */
 305                         if ((p + 2 < e) && (p[2] == '.') && ((p + 3 >= e) || (p[3] == '/'))) {
 306                                 while ((cp > canonpath) && (*--cp != '/'))
 307                                         ;
 308
 309                                 p += 3;
 310                                 continue;
 311                         }
 312                 }
 313
 314 next:
 315                 *cp++ = *p++;
 316         }
 317
 318         /* remove trailing slash if not root / */
 319         if ((cp > canonpath + 1) && (cp[-1] == '/'))
 320                 cp--;
 321         else if (cp == canonpath)
 322                 *cp++ = '/';
 323
 324         *cp = '\0';
 325
 326         return canonpath;
 327 }
 328
 329 static int
 330 response(bool success, const char *message)
 331 {
 332         char *chksum;
 333         struct stat s;
 334
 335         printf("Status: 200 OK\r\n");
 336         printf("Content-Type: text/plain\r\n\r\n{\n");
 337
 338         if (success)
 339         {
 340                 if (!stat(st.filename, &s))
 341                         printf("\t\"size\": %u,\n", (unsigned int)s.st_size);
 342                 else
 343                         printf("\t\"size\": null,\n");
 344
 345                 chksum = checksum("md5sum", 32, st.filename);
 346                 printf("\t\"checksum\": %s%s%s,\n",
 347                         chksum ? "\"" : "",
 348                         chksum ? chksum : "null",
 349                         chksum ? "\"" : "");
 350
 351                 chksum = checksum("sha256sum", 64, st.filename);
 352                 printf("\t\"sha256sum\": %s%s%s\n",
 353                         chksum ? "\"" : "",
 354                         chksum ? chksum : "null",
 355                         chksum ? "\"" : "");
 356         }
 357         else
 358         {
 359                 if (message)
 360                         printf("\t\"message\": \"%s\",\n", message);
 361
 362                 printf("\t\"failure\": [ %u, \"%s\" ]\n", errno, strerror(errno));
 363
 364                 if (st.filefd > -1)
 365                         unlink(st.filename);
 366         }
 367
 368         printf("}\n");
 369
 370         return -1;
 371 }
 372
 373 static int
 374 failure(int code, int e, const char *message)
 375 {
 376         printf("Status: %d %s\r\n", code, message);
 377         printf("Content-Type: text/plain\r\n\r\n");
 378         printf("%s", message);
 379
 380         if (e)
 381                 printf(": %s", strerror(e));
 382
 383         printf("\n");
 384
 385         return -1;
 386 }
 387
 388 static int
 389 filecopy(void)
 390 {
 391         int len;
 392         char buf[4096];
 393
 394         if (!st.filedata)
 395         {
 396                 close(st.tempfd);
 397                 errno = EINVAL;
 398                 return response(false, "No file data received");
 399         }
 400
 401         if (lseek(st.tempfd, 0, SEEK_SET) < 0)
 402         {
 403                 close(st.tempfd);
 404                 return response(false, "Failed to rewind temp file");
 405         }
 406
 407         st.filefd = open(st.filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
 408
 409         if (st.filefd < 0)
 410         {
 411                 close(st.tempfd);
 412                 return response(false, "Failed to open target file");
 413         }
 414
 415         while ((len = read(st.tempfd, buf, sizeof(buf))) > 0)
 416         {
 417                 if (write(st.filefd, buf, len) != len)
 418                 {
 419                         close(st.tempfd);
 420                         close(st.filefd);
 421                         return response(false, "I/O failure while writing target file");
 422                 }
 423         }
 424
 425         close(st.tempfd);
 426         close(st.filefd);
 427
 428         if (chmod(st.filename, st.filemode))
 429                 return response(false, "Failed to chmod target file");
 430
 431         return 0;
 432 }
 433
 434 static int
 435 header_field(multipart_parser *p, const char *data, size_t len)
 436 {
 437         st.is_content_disposition = !strncasecmp(data, "Content-Disposition", len);
 438         return 0;
 439 }
 440
 441 static int
 442 header_value(multipart_parser *p, const char *data, size_t len)
 443 {
 444         int i, j;
 445
 446         if (!st.is_content_disposition)
 447                 return 0;
 448
 449         if (len < 10 || strncasecmp(data, "form-data", 9))
 450                 return 0;
 451
 452         for (data += 9, len -= 9; *data == ' ' || *data == ';'; data++, len--);
 453
 454         if (len < 8 || strncasecmp(data, "name=\"", 6))
 455                 return 0;
 456
 457         for (data += 6, len -= 6, i = 0; i <= len; i++)
 458         {
 459                 if (*(data + i) != '"')
 460                         continue;
 461
 462                 for (j = 1; j < sizeof(parts) / sizeof(parts[0]); j++)
 463                         if (!strncmp(data, parts[j], i))
 464                                 st.parttype = j;
 465
 466                 break;
 467         }
 468
 469         return 0;
 470 }
 471
 472 static int
 473 data_begin_cb(multipart_parser *p)
 474 {
 475         char tmpname[24] = "/tmp/luci-upload.XXXXXX";
 476
 477         if (st.parttype == PART_FILEDATA)
 478         {
 479                 if (!st.sessionid)
 480                         return response(false, "File data without session");
 481
 482                 if (!st.filename)
 483                         return response(false, "File data without name");
 484
 485                 if (!session_access(st.sessionid, "file", st.filename, "write"))
 486                         return response(false, "Access to path denied by ACL");
 487
 488                 st.tempfd = mkstemp(tmpname);
 489
 490                 if (st.tempfd < 0)
 491                         return response(false, "Failed to create temporary file");
 492
 493                 unlink(tmpname);
 494         }
 495
 496         return 0;
 497 }
 498
 499 static int
 500 data_cb(multipart_parser *p, const char *data, size_t len)
 501 {
 502         switch (st.parttype)
 503         {
 504         case PART_SESSIONID:
 505                 st.sessionid = datadup(data, len);
 506                 break;
 507
 508         case PART_FILENAME:
 509                 st.filename = canonicalize_path(data, len);
 510                 break;
 511
 512         case PART_FILEMODE:
 513                 st.filemode = strtoul(data, NULL, 8);
 514                 break;
 515
 516         case PART_FILEDATA:
 517                 if (write(st.tempfd, data, len) != len)
 518                 {
 519                         close(st.tempfd);
 520                         return response(false, "I/O failure while writing temporary file");
 521                 }
 522
 523                 if (!st.filedata)
 524                         st.filedata = !!len;
 525
 526                 break;
 527
 528         default:
 529                 break;
 530         }
 531
 532         return 0;
 533 }
 534
 535 static int
 536 data_end_cb(multipart_parser *p)
 537 {
 538         if (st.parttype == PART_SESSIONID)
 539         {
 540                 if (!session_access(st.sessionid, "cgi-io", "upload", "write"))
 541                 {
 542                         errno = EPERM;
 543                         return response(false, "Upload permission denied");
 544                 }
 545         }
 546         else if (st.parttype == PART_FILEDATA)
 547         {
 548                 if (st.tempfd < 0)
 549                         return response(false, "Internal program failure");
 550
 551 #if 0
 552                 /* prepare directory */
 553                 for (ptr = st.filename; *ptr; ptr++)
 554                 {
 555                         if (*ptr == '/')
 556                         {
 557                                 *ptr = 0;
 558
 559                                 if (mkdir(st.filename, 0755))
 560                                 {
 561                                         unlink(st.tmpname);
 562                                         return response(false, "Failed to create destination directory");
 563                                 }
 564
 565                                 *ptr = '/';
 566                         }
 567                 }
 568 #endif
 569
 570                 if (filecopy())
 571                         return -1;
 572
 573                 return response(true, NULL);
 574         }
 575
 576         st.parttype = PART_UNKNOWN;
 577         return 0;
 578 }
 579
 580 static multipart_parser *
 581 init_parser(void)
 582 {
 583         char *boundary;
 584         const char *var;
 585
 586         multipart_parser *p;
 587         static multipart_parser_settings s = {
 588                 .on_part_data        = data_cb,
 589                 .on_headers_complete = data_begin_cb,
 590                 .on_part_data_end    = data_end_cb,
 591                 .on_header_field     = header_field,
 592                 .on_header_value     = header_value
 593         };
 594
 595         var = getenv("CONTENT_TYPE");
 596
 597         if (!var || strncmp(var, "multipart/form-data;", 20))
 598                 return NULL;
 599
 600         for (var += 20; *var && *var != '='; var++);
 601
 602         if (*var++ != '=')
 603                 return NULL;
 604
 605         boundary = malloc(strlen(var) + 3);
 606
 607         if (!boundary)
 608                 return NULL;
 609
 610         strcpy(boundary, "--");
 611         strcpy(boundary + 2, var);
 612
 613         st.tempfd = -1;
 614         st.filefd = -1;
 615         st.filemode = 0600;
 616
 617         p = multipart_parser_init(boundary, &s);
 618
 619         free(boundary);
 620
 621         return p;
 622 }
 623
 624 static int
 625 main_upload(int argc, char *argv[])
 626 {
 627         int rem, len;
 628         char buf[4096];
 629         multipart_parser *p;
 630
 631         p = init_parser();
 632
 633         if (!p)
 634         {
 635                 errno = EINVAL;
 636                 return response(false, "Invalid request");
 637         }
 638
 639         while ((len = read(0, buf, sizeof(buf))) > 0)
 640         {
 641                 rem = multipart_parser_execute(p, buf, len);
 642
 643                 if (rem < len)
 644                         break;
 645         }
 646
 647         multipart_parser_free(p);
 648
 649         /* read remaining post data */
 650         while ((len = read(0, buf, sizeof(buf))) > 0);
 651
 652         return 0;
 653 }
 654
 655 static int
 656 main_download(int argc, char **argv)
 657 {
 658         char *fields[] = { "sessionid", NULL, "path", NULL, "filename", NULL, "mimetype", NULL };
 659         unsigned long long size = 0;
 660         char *p, buf[4096];
 661         ssize_t len = 0;
 662         struct stat s;
 663         int rfd;
 664
 665         postdecode(fields, 4);
 666
 667         if (!fields[1] || !session_access(fields[1], "cgi-io", "download", "read"))
 668                 return failure(403, 0, "Download permission denied");
 669
 670         if (!fields[3] || !session_access(fields[1], "file", fields[3], "read"))
 671                 return failure(403, 0, "Access to path denied by ACL");
 672
 673         if (stat(fields[3], &s))
 674                 return failure(404, errno, "Failed to stat requested path");
 675
 676         if (!S_ISREG(s.st_mode) && !S_ISBLK(s.st_mode))
 677                 return failure(403, 0, "Requested path is not a regular file or block device");
 678
 679         for (p = fields[5]; p && *p; p++)
 680                 if (!isalnum(*p) && !strchr(" ()<>@,;:[]?.=%", *p))
 681                         return failure(400, 0, "Invalid characters in filename");
 682
 683         for (p = fields[7]; p && *p; p++)
 684                 if (!isalnum(*p) && !strchr(" .;=/-", *p))
 685                         return failure(400, 0, "Invalid characters in mimetype");
 686
 687         rfd = open(fields[3], O_RDONLY);
 688
 689         if (rfd < 0)
 690                 return failure(500, errno, "Failed to open requested path");
 691
 692         if (S_ISBLK(s.st_mode))
 693                 ioctl(rfd, BLKGETSIZE64, &size);
 694         else
 695                 size = (unsigned long long)s.st_size;
 696
 697         printf("Status: 200 OK\r\n");
 698         printf("Content-Type: %s\r\n", fields[7] ? fields[7] : "application/octet-stream");
 699
 700         if (fields[5])
 701                 printf("Content-Disposition: attachment; filename=\"%s\"\r\n", fields[5]);
 702
 703         printf("Content-Length: %llu\r\n\r\n", size);
 704         fflush(stdout);
 705
 706         while (size > 0) {
 707                 len = sendfile(1, rfd, NULL, size);
 708
 709                 if (len == -1) {
 710                         if (errno == ENOSYS || errno == EINVAL) {
 711                                 while ((len = read(rfd, buf, sizeof(buf))) > 0)
 712                                         fwrite(buf, len, 1, stdout);
 713
 714                                 fflush(stdout);
 715                                 break;
 716                         }
 717
 718                         if (errno == EINTR || errno == EAGAIN)
 719                                 continue;
 720                 }
 721
 722                 if (len <= 0)
 723                         break;
 724
 725                 size -= len;
 726         }
 727
 728         close(rfd);
 729
 730         return 0;
 731 }
 732
 733 static int
 734 main_backup(int argc, char **argv)
 735 {
 736         pid_t pid;
 737         time_t now;
 738         int len;
 739         int status;
 740         int fds[2];
 741         char datestr[16] = { 0 };
 742         char hostname[64] = { 0 };
 743         char *fields[] = { "sessionid", NULL };
 744
 745         if (!postdecode(fields, 1) || !session_access(fields[1], "cgi-io", "backup", "read"))
 746                 return failure(403, 0, "Backup permission denied");
 747
 748         if (pipe(fds))
 749                 return failure(500, errno, "Failed to spawn pipe");
 750
 751         switch ((pid = fork()))
 752         {
 753         case -1:
 754                 return failure(500, errno, "Failed to fork process");
 755
 756         case 0:
 757                 dup2(fds[1], 1);
 758
 759                 close(0);
 760                 close(2);
 761                 close(fds[0]);
 762                 close(fds[1]);
 763
 764                 chdir("/");
 765
 766                 execl("/sbin/sysupgrade", "/sbin/sysupgrade",
 767                       "--create-backup", "-", NULL);
 768
 769                 return -1;
 770
 771         default:
 772                 now = time(NULL);
 773                 strftime(datestr, sizeof(datestr) - 1, "%Y-%m-%d", localtime(&now));
 774
 775                 if (gethostname(hostname, sizeof(hostname) - 1))
 776                         sprintf(hostname, "OpenWrt");
 777
 778                 printf("Status: 200 OK\r\n");
 779                 printf("Content-Type: application/x-targz\r\n");
 780                 printf("Content-Disposition: attachment; "
 781                        "filename=\"backup-%s-%s.tar.gz\"\r\n\r\n", hostname, datestr);
 782
 783                 fflush(stdout);
 784
 785                 do {
 786                         len = splice(fds[0], NULL, 1, NULL, 4096, SPLICE_F_MORE);
 787                 } while (len > 0);
 788
 789                 waitpid(pid, &status, 0);
 790
 791                 close(fds[0]);
 792                 close(fds[1]);
 793
 794                 return 0;
 795         }
 796 }
 797
 798 int main(int argc, char **argv)
 799 {
 800         if (strstr(argv[0], "cgi-upload"))
 801                 return main_upload(argc, argv);
 802         else if (strstr(argv[0], "cgi-download"))
 803                 return main_download(argc, argv);
 804         else if (strstr(argv[0], "cgi-backup"))
 805                 return main_backup(argc, argv);
 806
 807         return -1;
 808 }