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auditd-config.c

/* auditd-config.c -- 
 * Copyright 2007 Red Hat Inc., Durham, North Carolina.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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
 *
 * Authors:
 *   Steve Grubb <sgrubb@redhat.com>
 * 
 */

#include "config.h"
#include "internal.h"
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <libgen.h>
#include <dirent.h>
#include <ctype.h>

/* Local prototypes */
00037 struct _pair
{
      const char *name;
      const char *value;
};

struct kw_pair 
{
      const char *name;
      int (*parser)(const char *, int, struct daemon_conf *);
};

struct nv_list
{ 
      const char *name;
      int option;
};

static char *get_line(FILE *f, char *buf);
static int nv_split(char *buf, struct _pair *nv);
static const struct kw_pair *kw_lookup(const char *val);
static int log_file_parser(const char *val, int line, 
            struct daemon_conf *config);
static int num_logs_parser(const char *val, int line, 
            struct daemon_conf *config);
static int log_format_parser(const char *val, int line, 
            struct daemon_conf *config);

static const struct kw_pair keywords[] = 
{
  {"log_file",                 log_file_parser },
  {"log_format",               log_format_parser },
  {"num_logs",                 num_logs_parser },
  { NULL,                      NULL }
};

static const struct nv_list log_formats[] =
{
  {"raw",  LF_RAW },
  {"nolog", LF_NOLOG },
  { NULL,  0 }
};


/*
 * Set everything to its default value
*/
static void clear_config(struct daemon_conf *config)
{
      config->qos = QOS_NON_BLOCKING;
      config->sender_uid = 0;
      config->sender_pid = 0;
      config->sender_ctx = NULL;
      config->log_file = strdup("/var/log/audit/audit.log");
      config->log_format = LF_RAW;
      config->log_group = 0;
      config->priority_boost = 3;
      config->flush =  FT_NONE;
      config->freq = 0;
      config->num_logs = 0L;
      config->dispatcher = NULL;
      config->node_name_format = N_NONE;
      config->node_name = NULL;
      config->max_log_size = 0L;
      config->max_log_size_action = SZ_IGNORE;
      config->space_left = 0L;
      config->space_left_action = FA_IGNORE;
      config->space_left_exe = NULL;
      config->action_mail_acct = strdup("root");
      config->admin_space_left= 0L;
      config->admin_space_left_action = FA_IGNORE;
      config->admin_space_left_exe = NULL;
      config->disk_full_action = FA_IGNORE;
      config->disk_full_exe = NULL;
      config->disk_error_action = FA_SYSLOG;
      config->disk_error_exe = NULL;
}

int load_config(struct daemon_conf *config, log_test_t lt)
{
      int fd, rc, lineno = 1;
      struct stat st;
      FILE *f;
      char buf[128];

      clear_config(config);
      lt = lt;

      /* open the file */
      rc = open(CONFIG_FILE, O_RDONLY|O_NOFOLLOW);
      if (rc < 0) {
            if (errno != ENOENT) {
                  audit_msg(LOG_ERR, "Error opening config file (%s)", 
                        strerror(errno));
                  return 1;
            }
            audit_msg(LOG_WARNING,
                  "Config file %s doesn't exist, skipping", CONFIG_FILE);
            return 0;
      }
      fd = rc;

      /* check the file's permissions: owned by root, not world writable,
       * not symlink.
       */
      if (fstat(fd, &st) < 0) {
            audit_msg(LOG_ERR, "Error fstat'ing config file (%s)", 
                  strerror(errno));
            close(fd);
            return 1;
      }
      if (st.st_uid != 0) {
            audit_msg(LOG_ERR, "Error - %s isn't owned by root", 
                  CONFIG_FILE);
            close(fd);
            return 1;
      }
      if (!S_ISREG(st.st_mode)) {
            audit_msg(LOG_ERR, "Error - %s is not a regular file", 
                  CONFIG_FILE);
            close(fd);
            return 1;
      }

      /* it's ok, read line by line */
      f = fdopen(fd, "r");
      if (f == NULL) {
            audit_msg(LOG_ERR, "Error - fdopen failed (%s)", 
                  strerror(errno));
            close(fd);
            return 1;
      }

      while (get_line(f, buf)) {
            // convert line into name-value pair
            const struct kw_pair *kw;
            struct _pair nv;
            rc = nv_split(buf, &nv);
            switch (rc) {
                  case 0: // fine
                        break;
                  case 1: // not the right number of tokens.
                        audit_msg(LOG_ERR, 
                        "Wrong number of arguments for line %d in %s", 
                              lineno, CONFIG_FILE);
                        break;
                  case 2: // no '=' sign
                        audit_msg(LOG_ERR, 
                              "Missing equal sign for line %d in %s", 
                              lineno, CONFIG_FILE);
                        break;
                  default: // something else went wrong... 
                        audit_msg(LOG_ERR, 
                              "Unknown error for line %d in %s", 
                              lineno, CONFIG_FILE);
                        break;
            }
            if (nv.name == NULL) {
                  lineno++;
                  continue;
            }
            if (nv.value == NULL) {
                  fclose(f);
                  return 1;
            }

            /* identify keyword or error */
            kw = kw_lookup(nv.name);
            if (kw->name) {
                  /* dispatch to keyword's local parser */
                  rc = kw->parser(nv.value, lineno, config);
                  if (rc != 0) {
                        fclose(f);
                        return 1; // local parser puts message out
                  }
            }

            lineno++;
      }

      fclose(f);
      return 0;
}

static char *get_line(FILE *f, char *buf)
{
      if (fgets_unlocked(buf, 128, f)) {
            /* remove newline */
            char *ptr = strchr(buf, 0x0a);
            if (ptr)
                  *ptr = 0;
            return buf;
      }
      return NULL;
}

static int nv_split(char *buf, struct _pair *nv)
{
      /* Get the name part */
      char *ptr;

      nv->name = NULL;
      nv->value = NULL;
      ptr = strtok(buf, " ");
      if (ptr == NULL)
            return 0; /* If there's nothing, go to next line */
      if (ptr[0] == '#')
            return 0; /* If there's a comment, go to next line */
      nv->name = ptr;

      /* Check for a '=' */
      ptr = strtok(NULL, " ");
      if (ptr == NULL)
            return 1;
      if (strcmp(ptr, "=") != 0)
            return 2;

      /* get the value */
      ptr = strtok(NULL, " ");
      if (ptr == NULL)
            return 1;
      nv->value = ptr;

      /* Make sure there's nothing else */
      ptr = strtok(NULL, " ");
      if (ptr)
            return 1;

      /* Everything is OK */
      return 0;
}

static const struct kw_pair *kw_lookup(const char *val)
{
      int i = 0;
      while (keywords[i].name != NULL) {
            if (strcasecmp(keywords[i].name, val) == 0)
                  break;
            i++;
      }
      return &keywords[i];
}
 
static int log_file_parser(const char *val, int line,struct daemon_conf *config)
{
      char *dir = NULL, *tdir, *base;
      DIR *d;
      int fd, mode;
      struct stat buf;

      /* split name into dir and basename. */
      tdir = strdup(val);
      if (tdir)
            dir = dirname(tdir);
      if (dir == NULL || strlen(dir) < 4) { //  '/var' is shortest dirname
            audit_msg(LOG_ERR, 
                  "The directory name: %s is too short - line %d", 
                  dir, line);
            free((void *)tdir);
            return 1;
      }

      base = basename((char *)val);
      if (base == 0 || strlen(base) == 0) {
            audit_msg(LOG_ERR, "The file name: %s is too short - line %d", 
                  base, line);
            free((void *)tdir);
            return 1;
      }
      
      /* verify the directory path exists */
      d = opendir(dir);
      if (d == NULL) {
            audit_msg(LOG_ERR, "Could not open dir %s (%s)", dir, 
                  strerror(errno));
            free((void *)tdir);
            return 1;
      }
      free((void *)tdir);
      closedir(d);

      /* if the file exists, see that its regular, owned by root, 
       * and not world anything */
      mode = O_RDONLY;

      fd = open(val, mode);
      if (fd < 0) {
            audit_msg(LOG_ERR, "Unable to open %s (%s)", val, 
                              strerror(errno));
            return 1;
      }
      if (fstat(fd, &buf) < 0) {
            audit_msg(LOG_ERR, "Unable to stat %s (%s)", 
                              val, strerror(errno));
            close(fd);
            return 1;
      }
      close(fd);
      if (!S_ISREG(buf.st_mode)) {
            audit_msg(LOG_ERR, "%s is not a regular file", val);
            return 1;
      }
      if (buf.st_uid != 0) {
            audit_msg(LOG_ERR, "%s is not owned by root", val);
            return 1;
      }
      if ( (buf.st_mode & (S_IXUSR|S_IWGRP|S_IXGRP|S_IRWXO)) ) {
            audit_msg(LOG_ERR, "%s permissions should be 0600 or 0640",
                        val);
            return 1;
      }
      if ( !(buf.st_mode & S_IWUSR) ) {
            audit_msg(LOG_ERR, "audit log is not writable by owner");
            return 1;
      }

      free((void *)config->log_file);
      config->log_file = strdup(val);
      if (config->log_file == NULL)
            return 1;
      return 0;
}

static int num_logs_parser(const char *val, int line, 
            struct daemon_conf *config)
{
      const char *ptr = val;
      unsigned long i;

      /* check that all chars are numbers */
      for (i=0; ptr[i]; i++) {
            if (!isdigit(ptr[i])) {
                  audit_msg(LOG_ERR, 
                        "Value %s should only be numbers - line %d",
                        val, line);
                  return 1;
            }
      }

      /* convert to unsigned long */
      errno = 0;
      i = strtoul(val, NULL, 10);
      if (errno) {
            audit_msg(LOG_ERR, 
                  "Error converting string to a number (%s) - line %d",
                  strerror(errno), line);
            return 1;
      }
      if (i > 99) {
            audit_msg(LOG_ERR, "num_logs must be 99 or less");
            return 1;
      }
      config->num_logs = i;
      return 0;
}

static int log_format_parser(const char *val, int line, 
            struct daemon_conf *config)
{
      int i;

      for (i=0; log_formats[i].name != NULL; i++) {
            if (strcasecmp(val, log_formats[i].name) == 0) {
                  config->log_format = log_formats[i].option;
                  return 0;
            }
      }
      audit_msg(LOG_ERR, "Option %s not found - line %d", val, line);
      return 1;
}

void free_config(struct daemon_conf *config)
{
      free((void*)config->sender_ctx);
      free((void*)config->log_file);
      free((void*)config->dispatcher);
      free((void *)config->node_name);
      free((void *)config->action_mail_acct);
      free((void *)config->space_left_exe);
      free((void *)config->admin_space_left_exe);
      free((void *)config->disk_full_exe);
      free((void *)config->disk_error_exe);
}


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