extcap/sdjournal.c

   1 /* sdjournal.c
   2  * sdjournal is an extcap tool used to dump systemd journal entries.
   3  *
   4  * Adapted from sshdump.
   5  * Copyright 2018, Gerald Combs and Dario Lombardo
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * SPDX-License-Identifier: GPL-2.0-or-later
  12  */
  13
  14 /*
  15  * To do:
  16  * - Add an option for sd_journal_open flags, e.g. SD_JOURNAL_LOCAL_ONLY.
  17  * - Add journalctl options - --boot, --machine, --directory, etc.
  18  */
  19
  20 #include "config.h"
  21 #define WS_LOG_DOMAIN "sdjournal"
  22
  23 #include <extcap/extcap-base.h>
  24 #include <wsutil/interface.h>
  25 #include <wsutil/file_util.h>
  26 #include <wsutil/filesystem.h>
  27 #include <wsutil/privileges.h>
  28 #include <wsutil/wslog.h>
  29 #include <writecap/pcapio.h>
  30 #include <wiretap/wtap.h>
  31
  32 #include <systemd/sd-journal.h>
  33 #include <systemd/sd-id128.h>
  34
  35 #include <errno.h>
  36 #include <string.h>
  37 #include <fcntl.h>
  38
  39 #define SDJOURNAL_VERSION_MAJOR "1"
  40 #define SDJOURNAL_VERSION_MINOR "0"
  41 #define SDJOURNAL_VERSION_RELEASE "0"
  42
  43 #define SDJOURNAL_EXTCAP_INTERFACE "sdjournal"
  44 #define BLOCK_TYPE_SYSTEMD_JOURNAL_EXPORT 0x00000009
  45
  46 enum {
  47         EXTCAP_BASE_OPTIONS_ENUM,
  48         OPT_HELP,
  49         OPT_VERSION,
  50         OPT_START_FROM
  51 };
  52
  53 static const struct ws_option longopts[] = {
  54         EXTCAP_BASE_OPTIONS,
  55         { "help", ws_no_argument, NULL, OPT_HELP},
  56         { "version", ws_no_argument, NULL, OPT_VERSION},
  57         { "start-from", ws_required_argument, NULL, OPT_START_FROM},
  58         { 0, 0, 0, 0}
  59 };
  60
  61 #define FLD_BOOT_ID "_BOOT_ID="
  62 #define FLD_BOOT_ID_LEN (8 + 1 + 33 + 1)
  63
  64 // The Journal Export Format specification doesn't place limits on entry
  65 // lengths or lines per entry. We do.
  66 #define ENTRY_BUF_LENGTH WTAP_MAX_PACKET_SIZE_STANDARD
  67 #define MAX_EXPORT_ENTRY_LENGTH (ENTRY_BUF_LENGTH - 4 - 4 - 4) // Block type - total length - total length
  68
  69 static int sdj_dump_entries(sd_journal *jnl, FILE* fp)
  70 {
  71         int ret = EXIT_SUCCESS;
  72         uint8_t *entry_buff = g_new(uint8_t, ENTRY_BUF_LENGTH);
  73         int jr = 0;
  74
  75         /*
  76          * Read journal entries and write them as packets. Output must
  77          * match `journalctl --output=export`.
  78          */
  79         while (jr == 0) {
  80                 char *cursor;
  81                 uint64_t pkt_rt_ts, mono_ts;
  82                 sd_id128_t boot_id;
  83                 char boot_id_str[FLD_BOOT_ID_LEN] = FLD_BOOT_ID;
  84                 uint32_t block_type = BLOCK_TYPE_SYSTEMD_JOURNAL_EXPORT;
  85                 uint32_t data_end = 8; // Block type + total length
  86                 const void *fld_data;
  87                 size_t fld_len;
  88                 uint64_t bytes_written = 0;
  89                 int err;
  90
  91                 memcpy(entry_buff, &block_type, 4);
  92
  93                 jr = sd_journal_next(jnl);
  94                 ws_debug("sd_journal_next: %d", jr);
  95                 if (jr < 0) {
  96                         ws_warning("Error fetching journal entry: %s", g_strerror(jr));
  97                         goto end;
  98                 } else if (jr == 0) {
  99                         sd_journal_wait(jnl, (uint64_t) -1);
 100                         continue;
 101                 }
 102
 103                 jr = sd_journal_get_cursor(jnl, &cursor);
 104                 if (jr < 0) {
 105                         ws_warning("Error fetching cursor: %s", g_strerror(jr));
 106                         goto end;
 107                 }
 108                 data_end += snprintf(entry_buff+data_end, MAX_EXPORT_ENTRY_LENGTH-data_end, "__CURSOR=%s\n", cursor);
 109                 free(cursor);
 110
 111                 jr = sd_journal_get_realtime_usec(jnl, &pkt_rt_ts);
 112                 if (jr < 0) {
 113                         ws_warning("Error fetching realtime timestamp: %s", g_strerror(jr));
 114                         goto end;
 115                 }
 116                 data_end += snprintf(entry_buff+data_end, MAX_EXPORT_ENTRY_LENGTH-data_end, "__REALTIME_TIMESTAMP=%" PRIu64 "\n", pkt_rt_ts);
 117
 118                 jr = sd_journal_get_monotonic_usec(jnl, &mono_ts, &boot_id);
 119                 if (jr < 0) {
 120                         ws_warning("Error fetching monotonic timestamp: %s", g_strerror(jr));
 121                         goto end;
 122                 }
 123                 sd_id128_to_string(boot_id, boot_id_str + strlen(FLD_BOOT_ID));
 124                 data_end += snprintf(entry_buff+data_end, MAX_EXPORT_ENTRY_LENGTH-data_end, "__MONOTONIC_TIMESTAMP=%" PRIu64 "\n%s\n", mono_ts, boot_id_str);
 125                 ws_debug("Entry header is %u bytes", data_end);
 126
 127                 SD_JOURNAL_FOREACH_DATA(jnl, fld_data, fld_len) {
 128                         uint8_t *eq_ptr = (uint8_t *) memchr(fld_data, '=', fld_len);
 129                         if (!eq_ptr) {
 130                                 ws_warning("Invalid field.");
 131                                 goto end;
 132                         }
 133                         if (g_utf8_validate((const char *) fld_data, (ssize_t) fld_len, NULL)) {
 134                                 // Allow for two trailing newlines, one here and one
 135                                 // at the end of the buffer.
 136                                 if (fld_len > MAX_EXPORT_ENTRY_LENGTH-data_end-2) {
 137                                         ws_debug("Breaking on UTF-8 field: %u + %zd", data_end, fld_len);
 138                                         break;
 139                                 }
 140                                 memcpy(entry_buff+data_end, fld_data, fld_len);
 141                                 data_end += (uint32_t) fld_len;
 142                                 entry_buff[data_end] = '\n';
 143                                 data_end++;
 144                         } else {
 145                                 // \n + 64-bit size + \n + trailing \n = 11
 146                                 if (fld_len > MAX_EXPORT_ENTRY_LENGTH-data_end-11) {
 147                                         ws_debug("Breaking on binary field: %u + %zd", data_end, fld_len);
 148                                         break;
 149                                 }
 150                                 ptrdiff_t name_len = eq_ptr - (const uint8_t *) fld_data;
 151                                 uint64_t le_data_len;
 152                                 le_data_len = htole64(fld_len - name_len - 1);
 153                                 memcpy(entry_buff+data_end, fld_data, name_len);
 154                                 data_end+= name_len;
 155                                 entry_buff[data_end] = '\n';
 156                                 data_end++;
 157                                 memcpy(entry_buff+data_end, &le_data_len, 8);
 158                                 data_end += 8;
 159                                 memcpy(entry_buff+data_end, (const uint8_t *) fld_data + name_len + 1, fld_len - name_len);
 160                                 data_end += fld_len - name_len;
 161                         }
 162                 }
 163
 164                 if (data_end % 4) {
 165                         size_t pad_len = 4 - (data_end % 4);
 166                         memset(entry_buff+data_end, '\0', pad_len);
 167                         data_end += pad_len;
 168                 }
 169
 170                 uint32_t total_len = data_end + 4;
 171                 memcpy (entry_buff+4, &total_len, 4);
 172                 memcpy (entry_buff+data_end, &total_len, 4);
 173
 174                 ws_debug("Attempting to write %u bytes", total_len);
 175                 if (!pcapng_write_block(fp, entry_buff, total_len, &bytes_written, &err)) {
 176                         ws_warning("Can't write event: %s", strerror(err));
 177                         ret = EXIT_FAILURE;
 178                         break;
 179                 }
 180
 181                 fflush(fp);
 182         }
 183
 184 end:
 185         g_free(entry_buff);
 186         return ret;
 187 }
 188
 189 static int sdj_start_export(const int start_from_entries, const bool start_from_end, const char* fifo)
 190 {
 191         FILE* fp = stdout;
 192         uint64_t bytes_written = 0;
 193         int err;
 194         sd_journal *jnl = NULL;
 195         sd_id128_t boot_id;
 196         char boot_id_str[FLD_BOOT_ID_LEN] = FLD_BOOT_ID;
 197         int ret = EXIT_FAILURE;
 198         char* err_info = NULL;
 199         char *appname;
 200         bool success;
 201         int jr = 0;
 202
 203         if (g_strcmp0(fifo, "-")) {
 204                 /* Open or create the output file */
 205                 fp = fopen(fifo, "wb");
 206                 if (fp == NULL) {
 207                         ws_warning("Error creating output file: %s (%s)", fifo, g_strerror(errno));
 208                         return EXIT_FAILURE;
 209                 }
 210         }
 211
 212
 213         appname = ws_strdup_printf(SDJOURNAL_EXTCAP_INTERFACE " (Wireshark) %s.%s.%s",
 214                 SDJOURNAL_VERSION_MAJOR, SDJOURNAL_VERSION_MINOR, SDJOURNAL_VERSION_RELEASE);
 215         success = pcapng_write_section_header_block(fp,
 216                                                         NULL,    /* Comment */
 217                                                         NULL,    /* HW */
 218                                                         NULL,    /* OS */
 219                                                         appname,
 220                                                         -1,      /* section_length */
 221                                                         &bytes_written,
 222                                                         &err);
 223         g_free(appname);
 224
 225         if (!success) {
 226                 ws_warning("Can't write pcapng file header");
 227                 goto cleanup;
 228         }
 229
 230         jr = sd_journal_open(&jnl, 0);
 231         if (jr < 0) {
 232                 ws_warning("Error opening journal: %s", g_strerror(jr));
 233                 goto cleanup;
 234         }
 235
 236         jr = sd_id128_get_boot(&boot_id);
 237         if (jr < 0) {
 238                 ws_warning("Error fetching system boot ID: %s", g_strerror(jr));
 239                 goto cleanup;
 240         }
 241
 242         sd_id128_to_string(boot_id, boot_id_str + strlen(FLD_BOOT_ID));
 243         jr = sd_journal_add_match(jnl, boot_id_str, strlen(boot_id_str));
 244         if (jr < 0) {
 245                 ws_warning("Error adding match: %s", g_strerror(jr));
 246                 goto cleanup;
 247         }
 248
 249         // According to the documentation, fields *might be* truncated to 64K.
 250         // Let's assume that 2048 is a good balance between fetching entire fields
 251         // and being able to fit as many fields as possible into a packet.
 252         sd_journal_set_data_threshold(jnl, 2048);
 253
 254         if (start_from_end) {
 255                 ws_debug("Attempting to seek %d entries from the end", start_from_entries);
 256                 jr = sd_journal_seek_tail(jnl);
 257                 if (jr < 0) {
 258                         ws_warning("Error starting at end: %s", g_strerror(jr));
 259                         goto cleanup;
 260                 }
 261                 jr = sd_journal_previous_skip(jnl, (uint64_t) start_from_entries + 1);
 262                 if (jr < 0) {
 263                         ws_warning("Error skipping backward: %s", g_strerror(jr));
 264                         goto cleanup;
 265                 }
 266         } else {
 267                 ws_debug("Attempting to seek %d entries from the beginning", start_from_entries);
 268                 jr = sd_journal_seek_head(jnl);
 269                 if (jr < 0) {
 270                         ws_warning("Error starting at beginning: %s", g_strerror(jr));
 271                         goto cleanup;
 272                 }
 273                 if (start_from_entries > 0) {
 274                         jr = sd_journal_next_skip(jnl, (uint64_t) start_from_entries);
 275                         if (jr < 0) {
 276                                 ws_warning("Error skipping forward: %s", g_strerror(jr));
 277                                 goto cleanup;
 278                         }
 279                 }
 280         }
 281
 282         /* read from channel and write into fp */
 283         if (sdj_dump_entries(jnl, fp) != 0) {
 284                 ws_warning("Error dumping entries");
 285                 goto cleanup;
 286         }
 287
 288         ret = EXIT_SUCCESS;
 289
 290 cleanup:
 291         if (jnl) {
 292                 sd_journal_close(jnl);
 293         }
 294
 295         if (err_info) {
 296                 ws_warning("%s", err_info);
 297         }
 298
 299         g_free(err_info);
 300
 301         /* clean up and exit */
 302         if (g_strcmp0(fifo, "-")) {
 303                 fclose(fp);
 304         }
 305         return ret;
 306 }
 307
 308 static int list_config(char *interface)
 309 {
 310         unsigned inc = 0;
 311
 312         if (!interface) {
 313                 ws_warning("ERROR: No interface specified.");
 314                 return EXIT_FAILURE;
 315         }
 316
 317         if (g_strcmp0(interface, SDJOURNAL_EXTCAP_INTERFACE)) {
 318                 ws_warning("ERROR: interface must be %s", SDJOURNAL_EXTCAP_INTERFACE);
 319                 return EXIT_FAILURE;
 320         }
 321
 322         printf("arg {number=%u}{call=--start-from}{display=Starting position}"
 323                         "{type=string}{tooltip=The journal starting position. Values "
 324                         "with a leading \"+\" start from the beginning, similar to the "
 325                         "\"tail\" command}{required=false}{group=Journal}\n", inc++);
 326
 327         extcap_config_debug(&inc);
 328
 329         return EXIT_SUCCESS;
 330 }
 331
 332 int main(int argc, char **argv)
 333 {
 334         char* configuration_init_error;
 335         int result;
 336         int option_idx = 0;
 337         int start_from_entries = 10;
 338         bool start_from_end = true;
 339         int ret = EXIT_FAILURE;
 340         extcap_parameters* extcap_conf = g_new0(extcap_parameters, 1);
 341         char* help_url;
 342         char* help_header = NULL;
 343
 344         /* Set the program name. */
 345         g_set_prgname("sdjournal");
 346
 347         /* Initialize log handler early so we can have proper logging during startup. */
 348         extcap_log_init();
 349
 350         /*
 351          * Get credential information for later use.
 352          */
 353         init_process_policies();
 354
 355         /*
 356          * Attempt to get the pathname of the directory containing the
 357          * executable file.
 358          */
 359         configuration_init_error = configuration_init(argv[0]);
 360         if (configuration_init_error != NULL) {
 361                 ws_warning("Can't get pathname of directory containing the extcap program: %s.",
 362                         configuration_init_error);
 363                 g_free(configuration_init_error);
 364         }
 365
 366         help_url = data_file_url("sdjournal.html");
 367         extcap_base_set_util_info(extcap_conf, argv[0], SDJOURNAL_VERSION_MAJOR, SDJOURNAL_VERSION_MINOR,
 368                         SDJOURNAL_VERSION_RELEASE, help_url);
 369         g_free(help_url);
 370         // We don't have an SDJOURNAL DLT, so use USER0 (147).
 371         extcap_base_register_interface(extcap_conf, SDJOURNAL_EXTCAP_INTERFACE, "systemd Journal Export", 147, "USER0");
 372
 373         help_header = ws_strdup_printf(
 374                         " %s --extcap-interfaces\n"
 375                         " %s --extcap-interface=%s --extcap-dlts\n"
 376                         " %s --extcap-interface=%s --extcap-config\n"
 377                         " %s --extcap-interface=%s --start-from=+0 --fifo=FILENAME --capture\n",
 378                         argv[0],
 379                         argv[0], SDJOURNAL_EXTCAP_INTERFACE,
 380                         argv[0], SDJOURNAL_EXTCAP_INTERFACE,
 381                         argv[0], SDJOURNAL_EXTCAP_INTERFACE);
 382         extcap_help_add_header(extcap_conf, help_header);
 383         g_free(help_header);
 384         extcap_help_add_option(extcap_conf, "--help", "print this help");
 385         extcap_help_add_option(extcap_conf, "--version", "print the version");
 386         extcap_help_add_option(extcap_conf, "--start-from <entry count>", "starting position");
 387
 388         ws_opterr = 0;
 389         ws_optind = 0;
 390
 391         if (argc == 1) {
 392                 extcap_help_print(extcap_conf);
 393                 goto end;
 394         }
 395
 396         while ((result = ws_getopt_long(argc, argv, ":", longopts, &option_idx)) != -1) {
 397
 398                 switch (result) {
 399
 400                         case OPT_HELP:
 401                                 extcap_help_print(extcap_conf);
 402                                 ret = EXIT_SUCCESS;
 403                                 goto end;
 404
 405                         case OPT_VERSION:
 406                                 extcap_version_print(extcap_conf);
 407                                 ret = EXIT_SUCCESS;
 408                                 goto end;
 409
 410                         case OPT_START_FROM:
 411                                 start_from_entries = (int) strtol(ws_optarg, NULL, 10);
 412                                 if (errno == EINVAL) {
 413                                         ws_warning("Invalid entry count: %s", ws_optarg);
 414                                         goto end;
 415                                 }
 416                                 if (strlen(ws_optarg) > 0 && ws_optarg[0] == '+') {
 417                                         start_from_end = false;
 418                                 }
 419                                 if (start_from_entries < 0) {
 420                                         start_from_end = true;
 421                                         start_from_entries *= -1;
 422                                 }
 423                                 ws_debug("start %d from %s", start_from_entries, start_from_end ? "end" : "beginning");
 424                                 break;
 425
 426                         case ':':
 427                                 /* missing option argument */
 428                                 ws_warning("Option '%s' requires an argument", argv[ws_optind - 1]);
 429                                 break;
 430
 431                         default:
 432                                 if (!extcap_base_parse_options(extcap_conf, result - EXTCAP_OPT_LIST_INTERFACES, ws_optarg)) {
 433                                         ws_warning("Invalid option: %s", argv[ws_optind - 1]);
 434                                         goto end;
 435                                 }
 436                 }
 437         }
 438
 439         extcap_cmdline_debug(argv, argc);
 440
 441         if (extcap_base_handle_interface(extcap_conf)) {
 442                 ret = EXIT_SUCCESS;
 443                 goto end;
 444         }
 445
 446         if (extcap_conf->show_config) {
 447                 ret = list_config(extcap_conf->interface);
 448                 goto end;
 449         }
 450
 451         if (extcap_conf->capture) {
 452                 ret = sdj_start_export(start_from_entries, start_from_end, extcap_conf->fifo);
 453         } else {
 454                 ws_debug("You should not come here... maybe some parameter missing?");
 455                 ret = EXIT_FAILURE;
 456         }
 457
 458 end:
 459         /* clean up stuff */
 460         extcap_base_cleanup(&extcap_conf);
 461         return ret;
 462 }
 463
 464 /*
 465  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 466  *
 467  * Local variables:
 468  * c-basic-offset: 8
 469  * tab-width: 8
 470  * indent-tabs-mode: t
 471  * End:
 472  *
 473  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 474  * :indentSize=8:tabSize=8:noTabs=false:
 475  */