87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
/* 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 sets the sk_bound_dev_if index in new AF_INET{6}
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* sockets opened by processes in the cgroup.
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*
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* - Attaches the new 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 "libbpf.h"
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char bpf_log_buf[BPF_LOG_BUF_SIZE];
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static int prog_load(int idx)
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{
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struct bpf_insn prog[] = {
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BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
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BPF_MOV64_IMM(BPF_REG_3, idx),
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BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, bound_dev_if)),
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BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, bound_dev_if)),
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BPF_MOV64_IMM(BPF_REG_0, 1), /* r0 = verdict */
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BPF_EXIT_INSN(),
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};
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size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn);
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return bpf_load_program(BPF_PROG_TYPE_CGROUP_SOCK, prog, insns_cnt,
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"GPL", 0, bpf_log_buf, BPF_LOG_BUF_SIZE);
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}
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static int usage(const char *argv0)
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{
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printf("Usage: %s cg-path device-index\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, prog_fd, ret;
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unsigned int idx;
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if (argc < 2)
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return usage(argv[0]);
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idx = if_nametoindex(argv[2]);
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if (!idx) {
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printf("Invalid device name\n");
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return EXIT_FAILURE;
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}
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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 EXIT_FAILURE;
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}
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prog_fd = prog_load(idx);
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printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
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if (prog_fd < 0) {
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printf("Failed to load prog: '%s'\n", strerror(errno));
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return EXIT_FAILURE;
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}
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ret = bpf_prog_attach(prog_fd, cg_fd, BPF_CGROUP_INET_SOCK_CREATE);
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if (ret < 0) {
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printf("Failed to attach prog to cgroup: '%s'\n",
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strerror(errno));
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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