tc/f_bpf.c

/*
 * f_bpf.c	BPF-based Classifier
 *
 *		This program is free software; you can distribute 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.
 *
 * Authors:	Daniel Borkmann <dborkman@redhat.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <limits.h>
#include <linux/filter.h>
#include <linux/if.h>

#include "utils.h"
#include "tc_util.h"
#include "tc_bpf.h"

static void explain(void)
{
	fprintf(stderr, "Usage: ... bpf ...\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " [inline]:     run bytecode BPF_BYTECODE\n");
	fprintf(stderr, " [from file]:  run bytecode-file FILE\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "               [ action ACTION_SPEC ]\n");
	fprintf(stderr, "               [ classid CLASSID ]\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "Where BPF_BYTECODE := \'s,c t f k,c t f k,c t f k,...\'\n");
	fprintf(stderr, "      c,t,f,k and s are decimals; s denotes number of 4-tuples\n");
	fprintf(stderr, "Where FILE points to a file containing the BPF_BYTECODE string\n");
	fprintf(stderr, "\nACTION_SPEC := ... look at individual actions\n");
	fprintf(stderr, "NOTE: CLASSID is parsed as hexadecimal input.\n");
}

static int bpf_parse_opt(struct filter_util *qu, char *handle,
			 int argc, char **argv, struct nlmsghdr *n)
{
	struct tcmsg *t = NLMSG_DATA(n);
	struct rtattr *tail;
	long h = 0;

	if (argc == 0)
		return 0;

	if (handle) {
		h = strtol(handle, NULL, 0);
		if (h == LONG_MIN || h == LONG_MAX) {
			fprintf(stderr, "Illegal handle \"%s\", must be "
				"numeric.\n", handle);
			return -1;
		}
	}

	t->tcm_handle = h;

	tail = (struct rtattr*)(((void*)n)+NLMSG_ALIGN(n->nlmsg_len));
	addattr_l(n, MAX_MSG, TCA_OPTIONS, NULL, 0);

	while (argc > 0) {
		if (matches(*argv, "run") == 0) {
			bool from_file;
			struct sock_filter bpf_ops[BPF_MAXINSNS];
			__u16 bpf_len;
			int ret;

			NEXT_ARG();
			if (strcmp(*argv, "bytecode-file") == 0) {
				from_file = true;
			} else if (strcmp(*argv, "bytecode") == 0) {
				from_file = false;
			} else {
				fprintf(stderr, "What is \"%s\"?\n", *argv);
				explain();
				return -1;
			}
			NEXT_ARG();
			ret = bpf_parse_ops(argc, argv, bpf_ops, from_file);
			if (ret < 0) {
				fprintf(stderr, "Illegal \"bytecode\"\n");
				return -1;
			}
			bpf_len = ret;
			addattr16(n, MAX_MSG, TCA_BPF_OPS_LEN, bpf_len);
			addattr_l(n, MAX_MSG, TCA_BPF_OPS, &bpf_ops,
				  bpf_len * sizeof(struct sock_filter));
		} else if (matches(*argv, "classid") == 0 ||
			   strcmp(*argv, "flowid") == 0) {
			unsigned handle;
			NEXT_ARG();
			if (get_tc_classid(&handle, *argv)) {
				fprintf(stderr, "Illegal \"classid\"\n");
				return -1;
			}
			addattr_l(n, MAX_MSG, TCA_BPF_CLASSID, &handle, 4);
		} else if (matches(*argv, "action") == 0) {
			NEXT_ARG();
			if (parse_action(&argc, &argv, TCA_BPF_ACT, n)) {
				fprintf(stderr, "Illegal \"action\"\n");
				return -1;
			}
			continue;
		} else if (matches(*argv, "police") == 0) {
			NEXT_ARG();
			if (parse_police(&argc, &argv, TCA_BPF_POLICE, n)) {
				fprintf(stderr, "Illegal \"police\"\n");
				return -1;
			}
			continue;
		} else if (strcmp(*argv, "help") == 0) {
			explain();
			return -1;
		} else {
			fprintf(stderr, "What is \"%s\"?\n", *argv);
			explain();
			return -1;
		}
		argc--; argv++;
	}

	tail->rta_len = (((void*)n)+n->nlmsg_len) - (void*)tail;
	return 0;
}

static int bpf_print_opt(struct filter_util *qu, FILE *f,
			 struct rtattr *opt, __u32 handle)
{
	struct rtattr *tb[TCA_BPF_MAX + 1];

	if (opt == NULL)
		return 0;

	parse_rtattr_nested(tb, TCA_BPF_MAX, opt);

	if (handle)
		fprintf(f, "handle 0x%x ", handle);

	if (tb[TCA_BPF_CLASSID]) {
		SPRINT_BUF(b1);
		fprintf(f, "flowid %s ",
			sprint_tc_classid(rta_getattr_u32(tb[TCA_BPF_CLASSID]), b1));
	}

	if (tb[TCA_BPF_OPS] && tb[TCA_BPF_OPS_LEN])
		bpf_print_ops(f, tb[TCA_BPF_OPS],
			      rta_getattr_u16(tb[TCA_BPF_OPS_LEN]));

	if (tb[TCA_BPF_POLICE]) {
		fprintf(f, "\n");
		tc_print_police(f, tb[TCA_BPF_POLICE]);
	}

	if (tb[TCA_BPF_ACT]) {
		tc_print_action(f, tb[TCA_BPF_ACT]);
	}

	return 0;
}

struct filter_util bpf_filter_util = {
	.id = "bpf",
	.parse_fopt = bpf_parse_opt,
	.print_fopt = bpf_print_opt,
};