mirror of
https://github.com/torvalds/linux
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d89af13c92
This commit refactors the existing cgroup program with libbpf bpf
loader. The original test_cgrp2_sock2 has keeped the bpf program
attached to the cgroup hierarchy even after the exit of user program.
To implement the same functionality with libbpf, this commit uses the
BPF_LINK_PINNING to pin the link attachment even after it is closed.
Since this uses LINK instead of ATTACH, detach of bpf program from
cgroup with 'test_cgrp2_sock' is not used anymore.
The code to mount the bpf was added to the .sh file in case the bpff
was not mounted on /sys/fs/bpf. Additionally, to fix the problem that
shell script cannot find the binary object from the current path,
relative path './' has been added in front of binary.
Fixes: 554ae6e792 ("samples/bpf: add userspace example for prohibiting sockets")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201124090310.24374-3-danieltimlee@gmail.com
96 lines
2 KiB
C
96 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* eBPF example program:
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*
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* - Loads eBPF program
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*
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* The eBPF program loads a filter from file and attaches the
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* program to a cgroup using BPF_PROG_ATTACH
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*/
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <string.h>
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#include <unistd.h>
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <net/if.h>
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#include <linux/bpf.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include "bpf_insn.h"
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static int usage(const char *argv0)
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{
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printf("Usage: %s cg-path filter-path [filter-id]\n", argv0);
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return EXIT_FAILURE;
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}
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int main(int argc, char **argv)
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{
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int cg_fd, err, ret = EXIT_FAILURE, filter_id = 0, prog_cnt = 0;
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const char *link_pin_path = "/sys/fs/bpf/test_cgrp2_sock2";
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struct bpf_link *link = NULL;
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struct bpf_program *progs[2];
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struct bpf_program *prog;
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struct bpf_object *obj;
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if (argc < 3)
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return usage(argv[0]);
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if (argc > 3)
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filter_id = atoi(argv[3]);
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cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
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if (cg_fd < 0) {
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printf("Failed to open cgroup path: '%s'\n", strerror(errno));
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return ret;
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}
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obj = bpf_object__open_file(argv[2], NULL);
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if (libbpf_get_error(obj)) {
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printf("ERROR: opening BPF object file failed\n");
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return ret;
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}
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bpf_object__for_each_program(prog, obj) {
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progs[prog_cnt] = prog;
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prog_cnt++;
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}
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if (filter_id >= prog_cnt) {
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printf("Invalid program id; program not found in file\n");
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goto cleanup;
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}
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/* load BPF program */
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if (bpf_object__load(obj)) {
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printf("ERROR: loading BPF object file failed\n");
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goto cleanup;
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}
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link = bpf_program__attach_cgroup(progs[filter_id], cg_fd);
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if (libbpf_get_error(link)) {
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printf("ERROR: bpf_program__attach failed\n");
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link = NULL;
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goto cleanup;
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}
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err = bpf_link__pin(link, link_pin_path);
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if (err < 0) {
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printf("ERROR: bpf_link__pin failed: %d\n", err);
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goto cleanup;
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}
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ret = EXIT_SUCCESS;
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cleanup:
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bpf_link__destroy(link);
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bpf_object__close(obj);
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return ret;
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}
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