tc: add cls_bpf frontend

This is the iproute2 part of the kernel patch "net: sched:
add BPF-based traffic classifier".

[Will re-submit later again for iproute2 when window for
 -next submissions opens.]
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>

tc/Makefile

@@ -22,6 +22,7 @@ TCMODULES += f_u32.o
 TCMODULES += f_route.o
 TCMODULES += f_fw.o
 TCMODULES += f_basic.o
+TCMODULES += f_bpf.o
 TCMODULES += f_flow.o
 TCMODULES += f_cgroup.o
 TCMODULES += q_dsmark.o

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 <linux/filter.h>
+#include <linux/if.h>
+
+#include "utils.h"
+#include "tc_util.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, "               [ police POLICE_SPEC ] [ 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, "\nNOTE: CLASSID is parsed as hexadecimal input.\n");
+}
+
+static int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len,
+			    char **bpf_string, bool *need_release,
+			    const char separator)
+{
+	char sp;
+
+	if (from_file) {
+		size_t tmp_len, op_len = sizeof("65535 255 255 4294967295,");
+		char *tmp_string;
+		FILE *fp;
+
+		tmp_len = sizeof("4096,") + BPF_MAXINSNS * op_len;
+		tmp_string = malloc(tmp_len);
+		if (tmp_string == NULL)
+			return -ENOMEM;
+
+		memset(tmp_string, 0, tmp_len);
+
+		fp = fopen(arg, "r");
+		if (fp == NULL) {
+			perror("Cannot fopen");
+			free(tmp_string);
+			return -ENOENT;
+		}
+
+		if (!fgets(tmp_string, tmp_len, fp)) {
+			free(tmp_string);
+			fclose(fp);
+			return -EIO;
+		}
+
+		fclose(fp);
+
+		*need_release = true;
+		*bpf_string = tmp_string;
+	} else {
+		*need_release = false;
+		*bpf_string = arg;
+	}
+
+	if (sscanf(*bpf_string, "%hu%c", bpf_len, &sp) != 2 ||
+	    sp != separator) {
+		if (*need_release)
+			free(*bpf_string);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int bpf_parse_ops(int argc, char **argv, struct nlmsghdr *n,
+			 bool from_file)
+{
+	char *bpf_string, *token, separator = ',';
+	struct sock_filter bpf_ops[BPF_MAXINSNS];
+	int ret = 0, i = 0;
+	bool need_release;
+	__u16 bpf_len = 0;
+
+	if (argc < 1)
+		return -EINVAL;
+	if (bpf_parse_string(argv[0], from_file, &bpf_len, &bpf_string,
+			     &need_release, separator))
+		return -EINVAL;
+	if (bpf_len == 0 || bpf_len > BPF_MAXINSNS) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	token = bpf_string;
+	while ((token = strchr(token, separator)) && (++token)[0]) {
+		if (i >= bpf_len) {
+			fprintf(stderr, "Real program length exceeds encoded "
+				"length parameter!\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (sscanf(token, "%hu %hhu %hhu %u,",
+			   &bpf_ops[i].code, &bpf_ops[i].jt,
+			   &bpf_ops[i].jf, &bpf_ops[i].k) != 4) {
+			fprintf(stderr, "Error at instruction %d!\n", i);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		i++;
+	}
+
+	if (i != bpf_len) {
+		fprintf(stderr, "Parsed program length is less than encoded"
+			"length parameter!\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	addattr_l(n, MAX_MSG, TCA_BPF_OPS_LEN, &bpf_len, sizeof(bpf_len));
+	addattr_l(n, MAX_MSG, TCA_BPF_OPS, &bpf_ops,
+		  bpf_len * sizeof(struct sock_filter));
+out:
+	if (need_release)
+		free(bpf_string);
+
+	return ret;
+}
+
+static void bpf_print_ops(FILE *f, struct rtattr *bpf_ops, __u16 len)
+{
+	struct sock_filter *ops = (struct sock_filter *) RTA_DATA(bpf_ops);
+	int i;
+
+	if (len == 0)
+		return;
+
+	fprintf(f, "bytecode \'%u,", len);
+
+	for (i = 0; i < len - 1; i++)
+		fprintf(f, "%hu %hhu %hhu %u,", ops[i].code, ops[i].jt,
+			ops[i].jf, ops[i].k);
+
+	fprintf(f, "%hu %hhu %hhu %u\'\n", ops[i].code, ops[i].jt,
+		ops[i].jf, ops[i].k);
+}
+
+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;
+			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();
+			if (bpf_parse_ops(argc, argv, n, from_file)) {
+				fprintf(stderr, "Illegal \"bytecode\"\n");
+				return -1;
+			}
+		} 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,
+};