tools: bpf: add bpftool

Add a simple tool for querying and updating BPF objects on the system.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/bpf/bpftool/common.c

@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2017 Netronome Systems, Inc.
+ *
+ * This software is dual licensed under the GNU General License Version 2,
+ * June 1991 as shown in the file COPYING in the top-level directory of this
+ * source tree or the BSD 2-Clause License provided below.  You have the
+ * option to license this software under the complete terms of either license.
+ *
+ * The BSD 2-Clause License:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      1. Redistributions of source code must retain the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer.
+ *
+ *      2. Redistributions in binary form must reproduce the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer in the documentation and/or other materials
+ *         provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/* Author: Jakub Kicinski <kubakici@wp.pl> */
+
+#include <errno.h>
+#include <libgen.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/limits.h>
+#include <linux/magic.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+static bool is_bpffs(char *path)
+{
+	struct statfs st_fs;
+
+	if (statfs(path, &st_fs) < 0)
+		return false;
+
+	return (unsigned long)st_fs.f_type == BPF_FS_MAGIC;
+}
+
+int open_obj_pinned_any(char *path, enum bpf_obj_type exp_type)
+{
+	enum bpf_obj_type type;
+	int fd;
+
+	fd = bpf_obj_get(path);
+	if (fd < 0) {
+		err("bpf obj get (%s): %s\n", path,
+		    errno == EACCES && !is_bpffs(dirname(path)) ?
+		    "directory not in bpf file system (bpffs)" :
+		    strerror(errno));
+		return -1;
+	}
+
+	type = get_fd_type(fd);
+	if (type < 0) {
+		close(fd);
+		return type;
+	}
+	if (type != exp_type) {
+		err("incorrect object type: %s\n", get_fd_type_name(type));
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32))
+{
+	unsigned int id;
+	char *endptr;
+	int err;
+	int fd;
+
+	if (!is_prefix(*argv, "id")) {
+		err("expected 'id' got %s\n", *argv);
+		return -1;
+	}
+	NEXT_ARG();
+
+	id = strtoul(*argv, &endptr, 0);
+	if (*endptr) {
+		err("can't parse %s as ID\n", *argv);
+		return -1;
+	}
+	NEXT_ARG();
+
+	if (argc != 1)
+		usage();
+
+	fd = get_fd_by_id(id);
+	if (fd < 0) {
+		err("can't get prog by id (%u): %s\n", id, strerror(errno));
+		return -1;
+	}
+
+	err = bpf_obj_pin(fd, *argv);
+	close(fd);
+	if (err) {
+		err("can't pin the object (%s): %s\n", *argv,
+		    errno == EACCES && !is_bpffs(dirname(*argv)) ?
+		    "directory not in bpf file system (bpffs)" :
+		    strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+const char *get_fd_type_name(enum bpf_obj_type type)
+{
+	static const char * const names[] = {
+		[BPF_OBJ_UNKNOWN]	= "unknown",
+		[BPF_OBJ_PROG]		= "prog",
+		[BPF_OBJ_MAP]		= "map",
+	};
+
+	if (type < 0 || type >= ARRAY_SIZE(names) || !names[type])
+		return names[BPF_OBJ_UNKNOWN];
+
+	return names[type];
+}
+
+int get_fd_type(int fd)
+{
+	char path[PATH_MAX];
+	char buf[512];
+	ssize_t n;
+
+	snprintf(path, sizeof(path), "/proc/%d/fd/%d", getpid(), fd);
+
+	n = readlink(path, buf, sizeof(buf));
+	if (n < 0) {
+		err("can't read link type: %s\n", strerror(errno));
+		return -1;
+	}
+	if (n == sizeof(path)) {
+		err("can't read link type: path too long!\n");
+		return -1;
+	}
+
+	if (strstr(buf, "bpf-map"))
+		return BPF_OBJ_MAP;
+	else if (strstr(buf, "bpf-prog"))
+		return BPF_OBJ_PROG;
+
+	return BPF_OBJ_UNKNOWN;
+}
+
+char *get_fdinfo(int fd, const char *key)
+{
+	char path[PATH_MAX];
+	char *line = NULL;
+	size_t line_n = 0;
+	ssize_t n;
+	FILE *fdi;
+
+	snprintf(path, sizeof(path), "/proc/%d/fdinfo/%d", getpid(), fd);
+
+	fdi = fopen(path, "r");
+	if (!fdi) {
+		err("can't open fdinfo: %s\n", strerror(errno));
+		return NULL;
+	}
+
+	while ((n = getline(&line, &line_n, fdi))) {
+		char *value;
+		int len;
+
+		if (!strstr(line, key))
+			continue;
+
+		fclose(fdi);
+
+		value = strchr(line, '\t');
+		if (!value || !value[1]) {
+			err("malformed fdinfo!?\n");
+			free(line);
+			return NULL;
+		}
+		value++;
+
+		len = strlen(value);
+		memmove(line, value, len);
+		line[len - 1] = '\0';
+
+		return line;
+	}
+
+	err("key '%s' not found in fdinfo\n", key);
+	free(line);
+	fclose(fdi);
+	return NULL;
+}