path: root/tc/m_xt.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * m_xt.c	xtables based targets
 *		utilities mostly ripped from iptables <duh, its the linux way>
 *
 * Authors:  J Hadi Salim (hadi@cyberus.ca)
 */

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <limits.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <xtables.h>
#include "utils.h"
#include "tc_util.h"
#include <linux/tc_act/tc_ipt.h>
#include <stdio.h>
#include <dlfcn.h>
#include <getopt.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
#ifndef XT_LIB_DIR
#       define XT_LIB_DIR "/lib/xtables"
#endif

#ifndef __ALIGN_KERNEL
#define __ALIGN_KERNEL(x, a)	\
	__ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
#define __ALIGN_KERNEL_MASK(x, mask) \
	(((x) + (mask)) & ~(mask))
#endif

#ifndef ALIGN
#define ALIGN(x, a)	__ALIGN_KERNEL((x), (a))
#endif

static const char *tname = "mangle";

char *lib_dir;

static const char * const ipthooks[] = {
	"NF_IP_PRE_ROUTING",
	"NF_IP_LOCAL_IN",
	"NF_IP_FORWARD",
	"NF_IP_LOCAL_OUT",
	"NF_IP_POST_ROUTING",
};

static struct option original_opts[] = {
	{
		.name = "jump",
		.has_arg = 1,
		.val = 'j'
	},
	{0, 0, 0, 0}
};

static struct xtables_globals tcipt_globals = {
	.option_offset = 0,
	.program_name = "tc-ipt",
	.program_version = "0.2",
	.orig_opts = original_opts,
	.opts = original_opts,
	.exit_err = NULL,
#if XTABLES_VERSION_CODE >= 11
	.compat_rev = xtables_compatible_revision,
#endif
};

/*
 * we may need to check for version mismatch
*/
static int
build_st(struct xtables_target *target, struct xt_entry_target *t)
{

	size_t size =
		    XT_ALIGN(sizeof(struct xt_entry_target)) + target->size;

	if (t == NULL) {
		target->t = xtables_calloc(1, size);
		target->t->u.target_size = size;
		strncpy(target->t->u.user.name, target->name,
			sizeof(target->t->u.user.name) - 1);
		target->t->u.user.revision = target->revision;

		if (target->init != NULL)
			target->init(target->t);
	} else {
		target->t = t;
	}
	return 0;

}

static void set_lib_dir(void)
{

	lib_dir = getenv("XTABLES_LIBDIR");
	if (!lib_dir) {
		lib_dir = getenv("IPTABLES_LIB_DIR");
		if (lib_dir)
			fprintf(stderr, "using deprecated IPTABLES_LIB_DIR\n");
	}
	if (lib_dir == NULL)
		lib_dir = XT_LIB_DIR;

}

static int get_xtables_target_opts(struct xtables_globals *globals,
				   struct xtables_target *m)
{
	struct option *opts;

#if XTABLES_VERSION_CODE >= 6
	opts = xtables_options_xfrm(globals->orig_opts,
				    globals->opts,
				    m->x6_options,
				    &m->option_offset);
#else
	opts = xtables_merge_options(globals->opts,
				     m->extra_opts,
				     &m->option_offset);
#endif
	if (!opts)
		return -1;
	globals->opts = opts;
	return 0;
}

static int parse_ipt(struct action_util *a, int *argc_p,
		     char ***argv_p, int tca_id, struct nlmsghdr *n)
{
	struct xtables_target *m = NULL;
#if XTABLES_VERSION_CODE >= 6
	struct ipt_entry fw = {};
#endif
	struct rtattr *tail;

	int c;
	char **argv = *argv_p;
	int argc;
	char k[FILTER_NAMESZ];
	int size = 0;
	int iok = 0, ok = 0;
	__u32 hook = 0, index = 0;

	/* copy tcipt_globals because .opts will be modified by iptables */
	struct xtables_globals tmp_tcipt_globals = tcipt_globals;

	xtables_init_all(&tmp_tcipt_globals, NFPROTO_IPV4);
	set_lib_dir();

	/* parse only up until the next action */
	for (argc = 0; argc < *argc_p; argc++) {
		if (!argv[argc] || !strcmp(argv[argc], "action"))
			break;
	}

	if (argc <= 2) {
		fprintf(stderr,
			"too few arguments for xt, need at least '-j <target>'\n");
		return -1;
	}

	while (1) {
		c = getopt_long(argc, argv, "j:", tmp_tcipt_globals.opts, NULL);
		if (c == -1)
			break;
		switch (c) {
		case 'j':
			m = xtables_find_target(optarg, XTF_TRY_LOAD);
			if (!m) {
				fprintf(stderr,
					" failed to find target %s\n\n",
					optarg);
				return -1;
			}

			if (build_st(m, NULL) < 0) {
				printf(" %s error\n", m->name);
				return -1;
			}

			if (get_xtables_target_opts(&tmp_tcipt_globals,
						    m) < 0) {
				fprintf(stderr,
					" failed to find additional options for target %s\n\n",
					optarg);
				return -1;
			}
			ok++;
			break;

		default:
#if XTABLES_VERSION_CODE >= 6
			if (m != NULL && m->x6_parse != NULL) {
				xtables_option_tpcall(c, argv, 0, m, &fw);
#else
			if (m != NULL && m->parse != NULL) {
				m->parse(c - m->option_offset, argv, 0,
					 &m->tflags, NULL, &m->t);
#endif
			} else {
				fprintf(stderr,
					"failed to find target %s\n\n", optarg);
				return -1;

			}
			ok++;
			break;
		}
	}

	if (argc > optind) {
		if (matches(argv[optind], "index") == 0) {
			if (get_u32(&index, argv[optind + 1], 10)) {
				fprintf(stderr, "Illegal \"index\"\n");
				xtables_free_opts(1);
				return -1;
			}
			iok++;

			optind += 2;
		}
	}

	if (!ok && !iok) {
		fprintf(stderr, " ipt Parser BAD!! (%s)\n", *argv);
		return -1;
	}

	/* check that we passed the correct parameters to the target */
#if XTABLES_VERSION_CODE >= 6
	if (m)
		xtables_option_tfcall(m);
#else
	if (m && m->final_check)
		m->final_check(m->tflags);
#endif

	{
		struct tcmsg *t = NLMSG_DATA(n);

		if (t->tcm_parent != TC_H_ROOT
		    && t->tcm_parent == TC_H_MAJ(TC_H_INGRESS)) {
			hook = NF_IP_PRE_ROUTING;
		} else {
			hook = NF_IP_POST_ROUTING;
		}
	}

	tail = addattr_nest(n, MAX_MSG, tca_id);
	fprintf(stdout, "tablename: %s hook: %s\n ", tname, ipthooks[hook]);
	fprintf(stdout, "\ttarget: ");

	if (m) {
		if (m->print)
			m->print(NULL, m->t, 0);
		else
			printf("%s ", m->name);
	}
	fprintf(stdout, " index %d\n", index);

	if (strlen(tname) >= 16) {
		size = 15;
		k[15] = 0;
	} else {
		size = 1 + strlen(tname);
	}
	strncpy(k, tname, size);

	addattr_l(n, MAX_MSG, TCA_IPT_TABLE, k, size);
	addattr_l(n, MAX_MSG, TCA_IPT_HOOK, &hook, 4);
	addattr_l(n, MAX_MSG, TCA_IPT_INDEX, &index, 4);
	if (m)
		addattr_l(n, MAX_MSG, TCA_IPT_TARG, m->t, m->t->u.target_size);
	addattr_nest_end(n, tail);

	argv += optind;
	*argc_p -= argc;
	*argv_p = argv;

	optind = 0;
	xtables_free_opts(1);

	if (m) {
		/* Clear flags if target will be used again */
		m->tflags = 0;
		m->used = 0;
		/* Free allocated memory */
		free(m->t);
	}

	return 0;

}

static int
print_ipt(struct action_util *au, FILE *f, struct rtattr *arg)
{
	struct xtables_target *m;
	struct rtattr *tb[TCA_IPT_MAX + 1];
	struct xt_entry_target *t = NULL;
	__u32 hook;

	if (arg == NULL)
		return 0;

	/* copy tcipt_globals because .opts will be modified by iptables */
	struct xtables_globals tmp_tcipt_globals = tcipt_globals;

	xtables_init_all(&tmp_tcipt_globals, NFPROTO_IPV4);
	set_lib_dir();

	parse_rtattr_nested(tb, TCA_IPT_MAX, arg);

	if (tb[TCA_IPT_TABLE] == NULL) {
		fprintf(stderr, "Missing ipt table name, assuming mangle\n");
	} else {
		fprintf(f, "tablename: %s ",
			rta_getattr_str(tb[TCA_IPT_TABLE]));
	}

	if (tb[TCA_IPT_HOOK] == NULL) {
		fprintf(stderr, "Missing ipt hook name\n ");
		return -1;
	}

	if (tb[TCA_IPT_TARG] == NULL) {
		fprintf(stderr, "Missing ipt target parameters\n");
		return -1;
	}

	hook = rta_getattr_u32(tb[TCA_IPT_HOOK]);
	fprintf(f, " hook: %s\n", ipthooks[hook]);

	t = RTA_DATA(tb[TCA_IPT_TARG]);
	m = xtables_find_target(t->u.user.name, XTF_TRY_LOAD);
	if (!m) {
		fprintf(stderr, " failed to find target %s\n\n",
			t->u.user.name);
		return -1;
	}
	if (build_st(m, t) < 0) {
		fprintf(stderr, " %s error\n", m->name);
		return -1;
	}

	if (get_xtables_target_opts(&tmp_tcipt_globals, m) < 0) {
		fprintf(stderr,
			" failed to find additional options for target %s\n\n",
			t->u.user.name);
		return -1;
	}
	fprintf(f, "\ttarget ");
	m->print(NULL, m->t, 0);
	if (tb[TCA_IPT_INDEX] == NULL) {
		fprintf(f, " [NULL ipt target index ]\n");
	} else {
		__u32 index;

		index = rta_getattr_u32(tb[TCA_IPT_INDEX]);
		fprintf(f, "\n\tindex %u", index);
	}

	if (tb[TCA_IPT_CNT]) {
		struct tc_cnt *c  = RTA_DATA(tb[TCA_IPT_CNT]);

		fprintf(f, " ref %d bind %d", c->refcnt, c->bindcnt);
	}
	if (show_stats) {
		if (tb[TCA_IPT_TM]) {
			struct tcf_t *tm = RTA_DATA(tb[TCA_IPT_TM]);

			print_tm(f, tm);
		}
	}
	print_nl();

	xtables_free_opts(1);

	return 0;
}

struct action_util xt_action_util = {
	.id = "xt",
	.parse_aopt = parse_ipt,
	.print_aopt = print_ipt,
};