File: kmsgsd.c

package info (click to toggle)
psad 2.4.3-1.2~deb9u1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 3,884 kB
  • sloc: perl: 13,751; ansic: 1,322; sh: 342; makefile: 74
file content (548 lines) | stat: -rw-r--r-- 17,897 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
/*
******************************************************************************
*
*  File: kmsgsd.c
*
*  Purpose: kmsgsd separates iptables messages from all other
*           kernel messages.
*
*  Strategy: read messages from the /var/log/psadfifo named pipe and
*            print any firewall related dop/reject/deny messages to
*            the psad data file "/var/log/psad/fwdata".
*
*  Author: Michael Rash (mbr@cipherdyne.org)
*
*  Credits:  (see the CREDITS file)
*
*  Copyright (C) 1999-2007 Michael Rash (mbr@cipherdyne.org)
*
*  License (GNU Public License):
*
*     This program is distributed in the hope that it will be useful,
*     but WITHOUT ANY WARRANTY; without even the implied warranty of
*     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*     GNU General Public License for more details.
*
*     You should have received a copy of the GNU General Public License
*     along with this program; if not, write to the Free Software
*     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
*     USA
******************************************************************************
*/

/* includes */
#include "psad.h"
#include <getopt.h>

/* defines */
#define CONFIG_FILE "/etc/psad/psad.conf"

/* Maximum number of overwrite files allowed on the command line */
#define MAX_OVW_FILES   3

/* globals */
static volatile sig_atomic_t received_sighup = 0;
extern char *optarg; /* for getopt */
extern int   optind; /* for getopt */
char *fw_msg_search[MAX_GEN_LEN];
char psadfifo_file[MAX_PATH_LEN];
char fwdata_file[MAX_PATH_LEN];
char fw_search_file[MAX_PATH_LEN];
char snort_sid_str[MAX_PATH_LEN];
char install_root[MAX_PATH_LEN];
char psad_dir[MAX_PATH_LEN];
char psad_fifo_dir[MAX_PATH_LEN];
char psad_run_dir[MAX_PATH_LEN];
char kmsgsd_pid_file[MAX_PATH_LEN];
int num_fw_search_strings;
int fw_search_all_flag;
unsigned char dump_cfg;

/* prototypes */
static void usage(void);
static void clean_settings(void);
static void parse_config(char *file);
static void check_config(void);
static void dump_config(void);
static int match_fw_msg(char *fw_mgs);
static void find_sub_var_value(
    char *value,
    char *sub_var,
    char *pre_str,
    char *post_str
);

static void expand_config_vars(void);
static void sighup_handler(int sig);

/* main */
int main(int argc, char *argv[]) {

    char **ovw_file_ptr;
    char  *overwrite_files[MAX_OVW_FILES+1];
    char   overwrite_cmd[MAX_PATH_LEN];
    char   config_file[MAX_PATH_LEN];
    char   buf[MAX_LINE_BUF];
    int    fifo_fd, fwdata_fd;  /* file descriptors */
    int    cmdlopt, numbytes;
#ifdef DEBUG
    int    matched_ipt_log_msg = 0;
    int    fwlinectr = 0;
#endif

#ifdef DEBUG
    fprintf(stderr, "[+] Entering DEBUG mode\n");
    fprintf(stderr, "[+] Firewall messages will be written to both ");
    fprintf(stderr, "STDOUT _and_ to fwdata.\n\n");
#endif

    overwrite_files[0] = NULL;
    strlcpy(config_file, CONFIG_FILE, MAX_PATH_LEN);
    dump_cfg = 0;

    while((cmdlopt = getopt(argc, argv, "c:O:Dh")) != -1) {
        switch(cmdlopt) {
            case 'c':
                strlcpy(config_file, optarg, MAX_PATH_LEN);
                break;
            case 'O':
                strlcpy(overwrite_cmd, optarg, MAX_PATH_LEN);
                list_to_array(overwrite_cmd, ',', overwrite_files, MAX_OVW_FILES);
                break;
            case 'D':
                dump_cfg = 1;
                break;
            default:
                usage();
        }
    }

    /* clean our settings */
    clean_settings();

    /* Parse both the overwrite and configuration file */
    for (ovw_file_ptr=overwrite_files; *ovw_file_ptr!=NULL; ovw_file_ptr++)
        parse_config(*ovw_file_ptr);
    parse_config(config_file);

    /* Check our settings */
    check_config();

    if (dump_cfg == 1)
        dump_config();

    /* make sure there isn't another kmsgsd already running */
    check_unique_pid(kmsgsd_pid_file, "kmsgsd");

#ifndef DEBUG
    /* become a daemon */
    daemonize_process(kmsgsd_pid_file);
#endif

    /* install signal handler for HUP signals */
    signal(SIGHUP, sighup_handler);

    /* start doing the real work now that the daemon is running and
     * the config file has been processed */

    /* open the psadfifo named pipe.  Note that we are opening the pipe
     * _without_ the O_NONBLOCK flag since we want the read on the file
     * descriptor to block until there is something new in the pipe.
     * Also, note that we are opening with O_RDWR, since this seems to
     * fix the problem with kmsgsd not blocking on the read() if the
     * system logger dies (and hence closes its file descriptor for the
     * psadfifo). */
    if ((fifo_fd = open(psadfifo_file, O_RDWR)) < 0) {
        fprintf(stderr, "[*] Could not open %s for reading.\n",
            psadfifo_file);
        exit(EXIT_FAILURE);  /* could not open psadfifo named pipe */
    }

    /* open the fwdata file in append mode so we can write messages from
     * the pipe into this file. */
    if ((fwdata_fd = open(fwdata_file,
            O_CREAT|O_WRONLY|O_APPEND, 0600)) < 0) {
        fprintf(stderr, "[*] Could not open %s for writing.\n", fwdata_file);
        exit(EXIT_FAILURE);  /* could not open fwdata file */
    }

    /* MAIN LOOP;
     * Read data from the pipe indefinitely (we opened it _without_
     * O_NONBLOCK) and write it to the fwdata file if it is a firewall message
     */
    while ((numbytes = read(fifo_fd, buf, MAX_LINE_BUF-1)) >= 0) {

#ifdef DEBUG
        fprintf(stderr,
            "read %d bytes from %s fifo.\n", numbytes, psadfifo_file);
#endif

        /* make sure the buf contents qualifies as a string */
        buf[numbytes] = '\0';

        if (received_sighup) {

            /* clear the signal flag */
            received_sighup = 0;

            /* clean our settings */
            clean_settings();

            /* reparse the config file since we received a HUP signal */
            for (ovw_file_ptr=overwrite_files; *ovw_file_ptr!=NULL; ovw_file_ptr++)
                parse_config(*ovw_file_ptr);
            parse_config(config_file);

            check_config();

            /* close file descriptors and re-open them after
             * re-reading config file */
            close(fifo_fd);
            close(fwdata_fd);

            /* re-open psadfifo and fwdata files */
            if ((fifo_fd = open(psadfifo_file, O_RDWR)) < 0) {
                fprintf(stderr, "[*] Could not open %s for reading.\n",
                    psadfifo_file);
                exit(EXIT_FAILURE);  /* could not open psadfifo named pipe */
            }

            if ((fwdata_fd = open(fwdata_file, O_CREAT|O_WRONLY|O_APPEND,
                    0600)) < 0) {
                fprintf(stderr, "[*] Could not open %s for writing.\n",
                    fwdata_file);
                exit(EXIT_FAILURE);  /* could not open fwdata file */
            }
            slogr("psad(kmsgsd)", "received HUP signal");
        }

        /* see if we matched a firewall message and write it to the
         * fwdata file */
        if ((strstr(buf, "OUT=") != NULL
                && strstr(buf, "IN=") != NULL)) {
            if (! fw_search_all_flag) {
                /* we are looking for specific log prefixes */
                if (match_fw_msg(buf) || strstr(buf, snort_sid_str) != NULL) {
                    if (write(fwdata_fd, buf, numbytes) < 0) {
                        exit(EXIT_FAILURE);  /* could not write to the fwdata file */
                    }
#ifdef DEBUG
                    matched_ipt_log_msg = 1;
#endif
                }
            } else {
                if (write(fwdata_fd, buf, numbytes) < 0)
                    exit(EXIT_FAILURE);  /* could not write to the fwdata file */
#ifdef DEBUG
                matched_ipt_log_msg = 1;
#endif
            }
#ifdef DEBUG
            if (matched_ipt_log_msg) {
                puts(buf);
                fprintf(stderr, "[+] Line matched search strings.\n");
                fwlinectr++;
                if (fwlinectr % 50 == 0)
                    fprintf(stderr,
                        "[+] Processed %d firewall lines.\n", fwlinectr);
                matched_ipt_log_msg = 0;
            } else {
                puts(buf);
                fprintf(stderr, "[-] Line did not match search strings.\n");
            }
#endif
        }
    }

    /* these statements don't get executed, but for completeness... */
    close(fifo_fd);
    close(fwdata_fd);

    exit(EXIT_SUCCESS);
}
/******************** end main ********************/

static int match_fw_msg(char *fw_msg)
{
    int i;
    for (i=0; i < num_fw_search_strings; i++)
        if (strstr(fw_msg, fw_msg_search[i]) != NULL)
            return 1;
    return 0;
}

static void parse_config(char * file)
{
    FILE *config_ptr;   /* FILE pointer to the config file */
    int linectr = 0, i;
    char config_buf[MAX_LINE_BUF];
    char tmp_fw_search_buf[MAX_GEN_LEN], *index;

    for (i=0; i < num_fw_search_strings; i++)
        if (fw_msg_search[i] != NULL)
            free(fw_msg_search[i]);

    num_fw_search_strings = 0;
    fw_msg_search[num_fw_search_strings] = NULL;

#ifdef DEBUG
    fprintf(stderr, "[+] Parsing file %s\n", file);
#endif

    if ((config_ptr = fopen(file, "r")) == NULL) {
        perror("[*] Could not open config file");
        exit(EXIT_FAILURE);
    }

    /* increment through each line of the config file */
    while ((fgets(config_buf, MAX_LINE_BUF, config_ptr)) != NULL) {
        linectr++;
        /* set the index pointer to the beginning of the line */
        index = config_buf;

        /* advance the index pointer through any whitespace
         * at the beginning of the line */
        while (*index == ' ' || *index == '\t') index++;

        /* skip comments and blank lines, etc. */
        if ((*index != '#') && (*index != '\n') &&
                (*index != ';') && (index != NULL)) {

            find_char_var("INSTALL_ROOT", install_root, index);
            find_char_var("PSAD_DIR", psad_dir, index);
            find_char_var("PSAD_FIFO_DIR", psad_fifo_dir, index);
            find_char_var("PSAD_RUN_DIR", psad_run_dir, index);
            find_char_var("SNORT_SID_STR", snort_sid_str, index);
            find_char_var("PSAD_FIFO_FILE", psadfifo_file, index);
            find_char_var("FW_DATA_FILE", fwdata_file, index);
            find_char_var("KMSGSD_PID_FILE", kmsgsd_pid_file, index);
            if (find_char_var("FW_MSG_SEARCH", tmp_fw_search_buf, index)) {
                fw_msg_search[num_fw_search_strings]
                    = (char *) safe_malloc(strlen(tmp_fw_search_buf)+1);
                strlcpy(fw_msg_search[num_fw_search_strings],
                    tmp_fw_search_buf, strlen(tmp_fw_search_buf)+1);
                num_fw_search_strings++;
            }
            if (find_char_var("FW_SEARCH_ALL", tmp_fw_search_buf, index)) {
                if (tmp_fw_search_buf[0] == 'N')
                    fw_search_all_flag = 0;
            }
        }
    }
    fclose(config_ptr);

    return;
}

static void expand_config_vars(void)
{
    char sub_var[MAX_GEN_LEN]  = "";
    char pre_str[MAX_GEN_LEN]  = "";
    char post_str[MAX_GEN_LEN] = "";
    int found_sub_var = 1, resolve_ctr = 0;

    while (found_sub_var) {
        resolve_ctr++;
        if (resolve_ctr >= 20) {
            fprintf(stderr, "[*] Exceeded maximum variable resolution attempts.\n");
            exit(EXIT_FAILURE);
        }
        found_sub_var = 0;

        if (has_sub_var("INSTALL_ROOT", install_root, sub_var,
                pre_str, post_str)) {
            find_sub_var_value(install_root, sub_var, pre_str, post_str);
            found_sub_var = 1;
        }

        if (has_sub_var("SNORT_SID_STR", snort_sid_str, sub_var,
                pre_str, post_str)) {
            find_sub_var_value(snort_sid_str, sub_var, pre_str, post_str);
            found_sub_var = 1;
        }

        if (has_sub_var("FW_DATA_FILE", fwdata_file, sub_var,
                pre_str, post_str)) {
            find_sub_var_value(fwdata_file, sub_var, pre_str, post_str);
            found_sub_var = 1;
        }

        if (has_sub_var("PSAD_FIFO_FILE", psadfifo_file, sub_var,
                pre_str, post_str)) {
            find_sub_var_value(psadfifo_file, sub_var, pre_str, post_str);
            found_sub_var = 1;
        }

        if (has_sub_var("KMSGSD_PID_FILE", kmsgsd_pid_file, sub_var,
                pre_str, post_str)) {
            find_sub_var_value(kmsgsd_pid_file, sub_var, pre_str, post_str);
            found_sub_var = 1;
        }
    }
    return;
}

static void find_sub_var_value(char *value, char *sub_var, char *pre_str,
    char *post_str)
{
    int found_var = 0;
    if (strncmp(sub_var, "PSAD_DIR", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, psad_dir, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "PSAD_FIFO_DIR", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, psad_fifo_dir, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "INSTALL_ROOT", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, install_root, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "PSAD_RUN_DIR", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, psad_run_dir, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "SNORT_SID_STR", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, snort_sid_str, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "FW_DATA_FILE", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, fwdata_file, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "PSAD_FIFO_FILE", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, psadfifo_file, MAX_GEN_LEN);
        found_var = 1;
    } else if (strncmp(sub_var, "KMSGSD_PID_FILE", MAX_GEN_LEN) == 0) {
        strlcpy(sub_var, kmsgsd_pid_file, MAX_GEN_LEN);
        found_var = 1;
    }

    if (found_var) {

        /* substitute the variable value */
        expand_sub_var_value(value, sub_var, pre_str, post_str);

    } else {
        fprintf(stderr, "[*] Could not resolve sub-var: %s to a value.\n",
            sub_var);
        exit(EXIT_FAILURE);
    }
    return;
}

static void dump_config(void)
{
    fprintf(stderr, "[+] dump_config()\n");
    fprintf(stderr, "    INSTALL_ROOT: %s\n", install_root);
    fprintf(stderr, "    PSAD_DIR: %s\n", psad_dir);
    fprintf(stderr, "    PSAD_RUN_DIR: %s\n", psad_run_dir);
    fprintf(stderr, "    PSAD_FIFO_FILE: %s\n", psadfifo_file);
    fprintf(stderr, "    FW_DATA_FILE: %s\n", fwdata_file);
    fprintf(stderr, "    SNORT_SID_STR: %s\n", snort_sid_str);
    fprintf(stderr, "    KMSGSD_PID_FILE: %s\n", kmsgsd_pid_file);

    exit(EXIT_SUCCESS);
}

static void check_config(void)
{
    unsigned char err;

#ifdef DEBUG
    fprintf(stderr, "[+] Checking configuration...\n");
#endif

    err = 1;
    if (psad_dir[0] == '\0')
        fprintf(stderr, "[*] Could not find PSAD_DIR\n");

    else if (install_root[0] == '\0')
        fprintf(stderr, "[*] Could not find INSTALL_ROOT\n");

    else if (psad_run_dir[0] == '\0')
        fprintf(stderr, "[*] Could not find PSAD_RUN_DIR\n");

    else if (psadfifo_file[0] == '\0')
        fprintf(stderr, "[*] Could not find PSAD_FIFO_FILE\n");

    else if (fwdata_file[0] == '\0')
        fprintf(stderr, "[*] Could not find FW_DATA_FILE\n");

    else if (snort_sid_str[0] == '\0')
        fprintf(stderr, "[*] Could not find SNORT_SID_STR\n");

    else if (kmsgsd_pid_file[0] == '\0')
        fprintf(stderr, "[*] Could not find KMSGSD_PID_FILE\n");

    /* Resolve any embedded variables */
    else {
        expand_config_vars();

        /* there are no FW_MSG_SEARCH vars in fw_search.conf; default
         * to "DROP".  Psad will generate a syslog warning.  */
        if (! fw_search_all_flag && num_fw_search_strings == 0) {
            fw_msg_search[num_fw_search_strings]
                = (char *) safe_malloc(strlen("DROP")+1);
            strlcpy(fw_msg_search[0], "DROP", strlen("DROP")+1);
            num_fw_search_strings++;
        }

        err = 0;
    }

    if (err == 1)
        exit(EXIT_FAILURE);
}

static void clean_settings (void)
{

#ifdef DEBUG
    fprintf(stderr, "[+] Cleaning settings\n");
#endif

    /* default to parse all iptables messages */
    num_fw_search_strings = 0;
    fw_search_all_flag    = 1;

    *psad_dir        = '\0';
    *psad_fifo_dir   = '\0';
    *install_root    = '\0';
    *psad_run_dir    = '\0';
    *psadfifo_file   = '\0';
    *fwdata_file     = '\0';
    *snort_sid_str   = '\0';
    *kmsgsd_pid_file = '\0';
}


static void sighup_handler(int sig)
{
    received_sighup = 1;
}

/*
 * Usage message to be displayed when -h option is supplied or a bad option
 * is passed to the daemon. This function ends the execution of the program.
 */
static void usage (void)
{
    fprintf(stderr,
"kmsgsd - separates iptables messages from all other kernel messages\n\n");

    fprintf(stderr, "[+] Version: %s\n", PSAD_VERSION);
    fprintf(stderr,
"    By Michael Rash (mbr@cipherdyne.org)\n"
"    URL: http://www.cipherdyne.org/psad/\n\n");

    fprintf(stderr, "Usage: kmsgsd [options]\n\n");

    fprintf(stderr,
"Options:\n"
"    -c <file>          - Specify path to config file instead of using the\n"
"                         default $config_file.\n"
"    -D                 - Dump  the  configuration values that psad\n"
"                         derives from the /etc/psad/psad.conf (or other\n"
"                         override files) on STDERR\n"
"    -h                 - Display this usage message and exit\n"
"    -O <file>          - Override config variable values that are normally\n"
"                         read from the /etc/psad/psad.conf file with\n"
"                         values from the specified file\n");

    exit(EXIT_FAILURE);
}