137 lines
2.7 KiB
C
137 lines
2.7 KiB
C
/* eBPF example program:
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*
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* - Creates arraymap in kernel with 4 bytes keys and 8 byte values
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*
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* - Loads eBPF program
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*
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* The eBPF program accesses the map passed in to store two pieces of
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* information. The number of invocations of the program, which maps
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* to the number of packets received, is stored to key 0. Key 1 is
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* incremented on each iteration by the number of bytes stored in
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* the skb.
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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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* - Every second, reads map[0] and map[1] to see how many bytes and
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* packets were seen on any socket of tasks in the given cgroup.
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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 <assert.h>
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#include <unistd.h>
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#include <linux/bpf.h>
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#include "libbpf.h"
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#include "cgroup_helpers.h"
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#define FOO "/foo"
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#define BAR "/foo/bar/"
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#define PING_CMD "ping -c1 -w1 127.0.0.1"
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char bpf_log_buf[BPF_LOG_BUF_SIZE];
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static int prog_load(int verdict)
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{
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int ret;
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struct bpf_insn prog[] = {
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BPF_MOV64_IMM(BPF_REG_0, verdict), /* 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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ret = bpf_load_program(BPF_PROG_TYPE_CGROUP_SKB,
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prog, insns_cnt, "GPL", 0,
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bpf_log_buf, BPF_LOG_BUF_SIZE);
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if (ret < 0) {
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log_err("Loading program");
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printf("Output from verifier:\n%s\n-------\n", bpf_log_buf);
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return 0;
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}
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return ret;
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}
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int main(int argc, char **argv)
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{
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int drop_prog, allow_prog, foo = 0, bar = 0, rc = 0;
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allow_prog = prog_load(1);
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if (!allow_prog)
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goto err;
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drop_prog = prog_load(0);
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if (!drop_prog)
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goto err;
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if (setup_cgroup_environment())
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goto err;
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/* Create cgroup /foo, get fd, and join it */
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foo = create_and_get_cgroup(FOO);
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if (!foo)
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goto err;
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if (join_cgroup(FOO))
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goto err;
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if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS)) {
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log_err("Attaching prog to /foo");
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goto err;
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}
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assert(system(PING_CMD) != 0);
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/* Create cgroup /foo/bar, get fd, and join it */
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bar = create_and_get_cgroup(BAR);
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if (!bar)
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goto err;
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if (join_cgroup(BAR))
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goto err;
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assert(system(PING_CMD) != 0);
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if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) {
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log_err("Attaching prog to /foo/bar");
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goto err;
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}
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assert(system(PING_CMD) == 0);
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if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) {
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log_err("Detaching program from /foo/bar");
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goto err;
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}
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assert(system(PING_CMD) != 0);
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if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) {
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log_err("Attaching prog to /foo/bar");
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goto err;
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}
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if (bpf_prog_detach(foo, BPF_CGROUP_INET_EGRESS)) {
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log_err("Detaching program from /foo");
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goto err;
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}
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assert(system(PING_CMD) == 0);
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goto out;
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err:
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rc = 1;
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out:
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close(foo);
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close(bar);
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cleanup_cgroup_environment();
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return rc;
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}
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