libipt_LOG.c revision c0a9ab93f49a3d2508c95d0ca1a01c1089983731 
1/* Shared library add-on to iptables to add LOG support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <syslog.h>
7#include <getopt.h>
8#include <iptables.h>
9#include <linux/netfilter_ipv4/ip_tables.h>
10#include <linux/netfilter_ipv4/ipt_LOG.h>
11
12#define LOG_DEFAULT_LEVEL LOG_WARNING
13
14#ifndef IPT_LOG_UID /* Old kernel */
15#define IPT_LOG_UID	0x08	/* Log UID owning local socket */
16#undef  IPT_LOG_MASK
17#define IPT_LOG_MASK	0x0f
18#endif
19
20/* Function which prints out usage message. */
21static void
22help(void)
23{
24	printf(
25"LOG v%s options:\n"
26" --log-level level		Level of logging (numeric or see syslog.conf)\n"
27" --log-prefix prefix		Prefix log messages with this prefix.\n\n"
28" --log-tcp-sequence		Log TCP sequence numbers.\n\n"
29" --log-tcp-options		Log TCP options.\n\n"
30" --log-ip-options		Log IP options.\n\n"
31" --log-uid			Log UID owning the local socket.\n\n",
32IPTABLES_VERSION);
33}
34
35static struct option opts[] = {
36	{ .name = "log-level",        .has_arg = 1, .flag = 0, .val = '!' },
37	{ .name = "log-prefix",       .has_arg = 1, .flag = 0, .val = '#' },
38	{ .name = "log-tcp-sequence", .has_arg = 0, .flag = 0, .val = '1' },
39	{ .name = "log-tcp-options",  .has_arg = 0, .flag = 0, .val = '2' },
40	{ .name = "log-ip-options",   .has_arg = 0, .flag = 0, .val = '3' },
41	{ .name = "log-uid",          .has_arg = 0, .flag = 0, .val = '4' },
42	{ .name = 0 }
43};
44
45/* Initialize the target. */
46static void
47init(struct xt_entry_target *t, unsigned int *nfcache)
48{
49	struct ipt_log_info *loginfo = (struct ipt_log_info *)t->data;
50
51	loginfo->level = LOG_DEFAULT_LEVEL;
52
53}
54
55struct ipt_log_names {
56	const char *name;
57	unsigned int level;
58};
59
60static struct ipt_log_names ipt_log_names[]
61= { { .name = "alert",   .level = LOG_ALERT },
62    { .name = "crit",    .level = LOG_CRIT },
63    { .name = "debug",   .level = LOG_DEBUG },
64    { .name = "emerg",   .level = LOG_EMERG },
65    { .name = "error",   .level = LOG_ERR },		/* DEPRECATED */
66    { .name = "info",    .level = LOG_INFO },
67    { .name = "notice",  .level = LOG_NOTICE },
68    { .name = "panic",   .level = LOG_EMERG },		/* DEPRECATED */
69    { .name = "warning", .level = LOG_WARNING }
70};
71
72static u_int8_t
73parse_level(const char *level)
74{
75	unsigned int lev = -1;
76	unsigned int set = 0;
77
78	if (string_to_number(level, 0, 7, &lev) == -1) {
79		unsigned int i = 0;
80
81		for (i = 0;
82		     i < sizeof(ipt_log_names) / sizeof(struct ipt_log_names);
83		     i++) {
84			if (strncasecmp(level, ipt_log_names[i].name,
85					strlen(level)) == 0) {
86				if (set++)
87					exit_error(PARAMETER_PROBLEM,
88						   "log-level `%s' ambiguous",
89						   level);
90				lev = ipt_log_names[i].level;
91			}
92		}
93
94		if (!set)
95			exit_error(PARAMETER_PROBLEM,
96				   "log-level `%s' unknown", level);
97	}
98
99	return (u_int8_t)lev;
100}
101
102#define IPT_LOG_OPT_LEVEL 0x01
103#define IPT_LOG_OPT_PREFIX 0x02
104#define IPT_LOG_OPT_TCPSEQ 0x04
105#define IPT_LOG_OPT_TCPOPT 0x08
106#define IPT_LOG_OPT_IPOPT 0x10
107#define IPT_LOG_OPT_UID 0x20
108
109/* Function which parses command options; returns true if it
110   ate an option */
111static int
112parse(int c, char **argv, int invert, unsigned int *flags,
113      const void *entry,
114      struct xt_entry_target **target)
115{
116	struct ipt_log_info *loginfo = (struct ipt_log_info *)(*target)->data;
117
118	switch (c) {
119	case '!':
120		if (*flags & IPT_LOG_OPT_LEVEL)
121			exit_error(PARAMETER_PROBLEM,
122				   "Can't specify --log-level twice");
123
124		if (check_inverse(optarg, &invert, NULL, 0))
125			exit_error(PARAMETER_PROBLEM,
126				   "Unexpected `!' after --log-level");
127
128		loginfo->level = parse_level(optarg);
129		*flags |= IPT_LOG_OPT_LEVEL;
130		break;
131
132	case '#':
133		if (*flags & IPT_LOG_OPT_PREFIX)
134			exit_error(PARAMETER_PROBLEM,
135				   "Can't specify --log-prefix twice");
136
137		if (check_inverse(optarg, &invert, NULL, 0))
138			exit_error(PARAMETER_PROBLEM,
139				   "Unexpected `!' after --log-prefix");
140
141		if (strlen(optarg) > sizeof(loginfo->prefix) - 1)
142			exit_error(PARAMETER_PROBLEM,
143				   "Maximum prefix length %u for --log-prefix",
144				   (unsigned int)sizeof(loginfo->prefix) - 1);
145
146		if (strlen(optarg) == 0)
147			exit_error(PARAMETER_PROBLEM,
148				   "No prefix specified for --log-prefix");
149
150		if (strlen(optarg) != strlen(strtok(optarg, "\n")))
151			exit_error(PARAMETER_PROBLEM,
152				   "Newlines not allowed in --log-prefix");
153
154		strcpy(loginfo->prefix, optarg);
155		*flags |= IPT_LOG_OPT_PREFIX;
156		break;
157
158	case '1':
159		if (*flags & IPT_LOG_OPT_TCPSEQ)
160			exit_error(PARAMETER_PROBLEM,
161				   "Can't specify --log-tcp-sequence "
162				   "twice");
163
164		loginfo->logflags |= IPT_LOG_TCPSEQ;
165		*flags |= IPT_LOG_OPT_TCPSEQ;
166		break;
167
168	case '2':
169		if (*flags & IPT_LOG_OPT_TCPOPT)
170			exit_error(PARAMETER_PROBLEM,
171				   "Can't specify --log-tcp-options twice");
172
173		loginfo->logflags |= IPT_LOG_TCPOPT;
174		*flags |= IPT_LOG_OPT_TCPOPT;
175		break;
176
177	case '3':
178		if (*flags & IPT_LOG_OPT_IPOPT)
179			exit_error(PARAMETER_PROBLEM,
180				   "Can't specify --log-ip-options twice");
181
182		loginfo->logflags |= IPT_LOG_IPOPT;
183		*flags |= IPT_LOG_OPT_IPOPT;
184		break;
185
186	case '4':
187		if (*flags & IPT_LOG_OPT_UID)
188			exit_error(PARAMETER_PROBLEM,
189				   "Can't specify --log-uid twice");
190
191		loginfo->logflags |= IPT_LOG_UID;
192		*flags |= IPT_LOG_OPT_UID;
193		break;
194
195	default:
196		return 0;
197	}
198
199	return 1;
200}
201
202/* Final check; nothing. */
203static void final_check(unsigned int flags)
204{
205}
206
207/* Prints out the targinfo. */
208static void
209print(const void *ip,
210      const struct xt_entry_target *target,
211      int numeric)
212{
213	const struct ipt_log_info *loginfo
214		= (const struct ipt_log_info *)target->data;
215	unsigned int i = 0;
216
217	printf("LOG ");
218	if (numeric)
219		printf("flags %u level %u ",
220		       loginfo->logflags, loginfo->level);
221	else {
222		for (i = 0;
223		     i < sizeof(ipt_log_names) / sizeof(struct ipt_log_names);
224		     i++) {
225			if (loginfo->level == ipt_log_names[i].level) {
226				printf("level %s ", ipt_log_names[i].name);
227				break;
228			}
229		}
230		if (i == sizeof(ipt_log_names) / sizeof(struct ipt_log_names))
231			printf("UNKNOWN level %u ", loginfo->level);
232		if (loginfo->logflags & IPT_LOG_TCPSEQ)
233			printf("tcp-sequence ");
234		if (loginfo->logflags & IPT_LOG_TCPOPT)
235			printf("tcp-options ");
236		if (loginfo->logflags & IPT_LOG_IPOPT)
237			printf("ip-options ");
238		if (loginfo->logflags & IPT_LOG_UID)
239			printf("uid ");
240		if (loginfo->logflags & ~(IPT_LOG_MASK))
241			printf("unknown-flags ");
242	}
243
244	if (strcmp(loginfo->prefix, "") != 0)
245		printf("prefix `%s' ", loginfo->prefix);
246}
247
248/* Saves the union ipt_targinfo in parsable form to stdout. */
249static void
250save(const void *ip, const struct xt_entry_target *target)
251{
252	const struct ipt_log_info *loginfo
253		= (const struct ipt_log_info *)target->data;
254
255	if (strcmp(loginfo->prefix, "") != 0)
256		printf("--log-prefix \"%s\" ", loginfo->prefix);
257
258	if (loginfo->level != LOG_DEFAULT_LEVEL)
259		printf("--log-level %d ", loginfo->level);
260
261	if (loginfo->logflags & IPT_LOG_TCPSEQ)
262		printf("--log-tcp-sequence ");
263	if (loginfo->logflags & IPT_LOG_TCPOPT)
264		printf("--log-tcp-options ");
265	if (loginfo->logflags & IPT_LOG_IPOPT)
266		printf("--log-ip-options ");
267	if (loginfo->logflags & IPT_LOG_UID)
268		printf("--log-uid ");
269}
270
271static
272struct iptables_target log
273= {
274    .name          = "LOG",
275    .version       = IPTABLES_VERSION,
276    .size          = IPT_ALIGN(sizeof(struct ipt_log_info)),
277    .userspacesize = IPT_ALIGN(sizeof(struct ipt_log_info)),
278    .help          = &help,
279    .init          = &init,
280    .parse         = &parse,
281    .final_check   = &final_check,
282    .print         = &print,
283    .save          = &save,
284    .extra_opts    = opts
285};
286
287void _init(void)
288{
289	register_target(&log);
290}
291