ebtables-compat: add log watcher extension

This patch adds the log 'watcher' extension.

The work was started by Giuseppe Longo <giuseppelng@gmail.com> and finised
by me.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/extensions/libebt_log.c b/extensions/libebt_log.c
new file mode 100644 (file)
index 0000000..0799185
--- /dev/null
+++ b/extensions/libebt_log.c
@@ -0,0 +1,197 @@
+/*
+ * Bart De Schuymer <bdschuym@pandora.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Giuseppe Longo <giuseppelng@gmail.com> adapted the original code to the
+ * xtables-compat environment in 2015.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <string.h>
+#include <getopt.h>
+#include <xtables.h>
+#include <linux/netfilter_bridge/ebt_log.h>
+
+#define LOG_DEFAULT_LEVEL LOG_INFO
+
+#define LOG_PREFIX '1'
+#define LOG_LEVEL  '2'
+#define LOG_ARP    '3'
+#define LOG_IP     '4'
+#define LOG_LOG    '5'
+#define LOG_IP6    '6'
+
+typedef struct _code {
+       char *c_name;
+       int c_val;
+} CODE;
+
+static CODE eight_priority[] = {
+       { "emerg", LOG_EMERG },
+       { "alert", LOG_ALERT },
+       { "crit", LOG_CRIT },
+       { "error", LOG_ERR },
+       { "warning", LOG_WARNING },
+       { "notice", LOG_NOTICE },
+       { "info", LOG_INFO },
+       { "debug", LOG_DEBUG }
+};
+
+static int name_to_loglevel(const char *arg)
+{
+       int i;
+
+       for (i = 0; i < 8; i++)
+               if (!strcmp(arg, eight_priority[i].c_name))
+                       return eight_priority[i].c_val;
+
+       /* return bad loglevel */
+       return 9;
+}
+
+static const struct option brlog_opts[] = {
+       { .name = "log-prefix",         .has_arg = true,  .val = LOG_PREFIX },
+       { .name = "log-level",          .has_arg = true,  .val = LOG_LEVEL  },
+       { .name = "log-arp",            .has_arg = false, .val = LOG_ARP    },
+       { .name = "log-ip",             .has_arg = false, .val = LOG_IP     },
+       { .name = "log",                .has_arg = false, .val = LOG_LOG    },
+       { .name = "log-ip6",            .has_arg = false, .val = LOG_IP6    },
+       XT_GETOPT_TABLEEND,
+};
+
+static void brlog_help(void)
+{
+       int i;
+
+       printf(
+"log options:\n"
+"--log               : use this if you're not specifying anything\n"
+"--log-level level   : level = [1-8] or a string\n"
+"--log-prefix prefix : max. %d chars.\n"
+"--log-ip            : put ip info. in the log for ip packets\n"
+"--log-arp           : put (r)arp info. in the log for (r)arp packets\n"
+"--log-ip6           : put ip6 info. in the log for ip6 packets\n"
+       , EBT_LOG_PREFIX_SIZE - 1);
+       for (i = 0; i < 8; i++)
+               printf("%d = %s\n", eight_priority[i].c_val,
+                                   eight_priority[i].c_name);
+}
+
+static void brlog_init(struct xt_entry_target *t)
+{
+       struct ebt_log_info *loginfo = (struct ebt_log_info *)t->data;
+
+       loginfo->bitmask = 0;
+       loginfo->prefix[0] = '\0';
+       loginfo->loglevel = LOG_NOTICE;
+}
+
+static int brlog_parse(int c, char **argv, int invert, unsigned int *flags,
+                      const void *entry, struct xt_entry_target **target)
+{
+       struct ebt_log_info *loginfo = (struct ebt_log_info *)(*target)->data;
+       long int i;
+       char *end;
+
+       switch (c) {
+       case LOG_PREFIX:
+               if (invert)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Unexpected `!` after --log-prefix");
+               if (strlen(optarg) > sizeof(loginfo->prefix) - 1)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Prefix too long");
+               if (strchr(optarg, '\"'))
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Use of \\\" is not allowed"
+                                     " in the prefix");
+               strcpy((char *)loginfo->prefix, (char *)optarg);
+               break;
+       case LOG_LEVEL:
+               i = strtol(optarg, &end, 16);
+               if (*end != '\0' || i < 0 || i > 7)
+                       loginfo->loglevel = name_to_loglevel(optarg);
+               else
+                       loginfo->loglevel = i;
+
+               if (loginfo->loglevel == 9)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Problem with the log-level");
+               break;
+       case LOG_IP:
+               if (invert)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Unexpected `!' after --log-ip");
+               loginfo->bitmask |= EBT_LOG_IP;
+               break;
+       case LOG_ARP:
+               if (invert)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Unexpected `!' after --log-arp");
+               loginfo->bitmask |= EBT_LOG_ARP;
+       case LOG_LOG:
+               if (invert)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Unexpected `!' after --log");
+               break;
+       case LOG_IP6:
+               if (invert)
+                       xtables_error(PARAMETER_PROBLEM,
+                                     "Unexpected `!' after --log-ip6");
+               loginfo->bitmask |= EBT_LOG_IP6;
+               break;
+       default:
+               return 0;
+       }
+
+       *flags |= loginfo->bitmask;
+       return 1;
+}
+
+static void brlog_final_check(unsigned int flags)
+{
+}
+
+static void brlog_print(const void *ip, const struct xt_entry_target *target,
+                       int numeric)
+{
+       struct ebt_log_info *loginfo = (struct ebt_log_info *)target->data;
+
+       printf("--log-level %s --log-prefix \"%s\"",
+               eight_priority[loginfo->loglevel].c_name,
+               loginfo->prefix);
+
+       if (loginfo->bitmask & EBT_LOG_IP)
+               printf(" --log-ip");
+       if (loginfo->bitmask & EBT_LOG_ARP)
+               printf(" --log-arp");
+       if (loginfo->bitmask & EBT_LOG_IP6)
+               printf(" --log-ip6");
+       printf(" ");
+}
+
+static struct xtables_target brlog_target = {
+       .name           = "log",
+       .revision       = 0,
+       .version        = XTABLES_VERSION,
+       .family         = NFPROTO_BRIDGE,
+       .size           = XT_ALIGN(sizeof(struct ebt_log_info)),
+       .userspacesize  = XT_ALIGN(sizeof(struct ebt_log_info)),
+       .init           = brlog_init,
+       .help           = brlog_help,
+       .parse          = brlog_parse,
+       .final_check    = brlog_final_check,
+       .print          = brlog_print,
+       .extra_opts     = brlog_opts,
+};
+
+void _init(void)
+{
+       xtables_register_target(&brlog_target);
+}