609b1c3275
Add option to detach programs from a cgroup. Signed-off-by: David Ahern <dsahern@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
208 lines
4.6 KiB
C
208 lines
4.6 KiB
C
/* eBPF example program:
|
|
*
|
|
* - Loads eBPF program
|
|
*
|
|
* The eBPF program sets the sk_bound_dev_if index in new AF_INET{6}
|
|
* sockets opened by processes in the cgroup.
|
|
*
|
|
* - Attaches the new program to a cgroup using BPF_PROG_ATTACH
|
|
*/
|
|
|
|
#define _GNU_SOURCE
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <stddef.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <net/if.h>
|
|
#include <inttypes.h>
|
|
#include <linux/bpf.h>
|
|
|
|
#include "libbpf.h"
|
|
|
|
char bpf_log_buf[BPF_LOG_BUF_SIZE];
|
|
|
|
static int prog_load(__u32 idx, __u32 mark, __u32 prio)
|
|
{
|
|
/* save pointer to context */
|
|
struct bpf_insn prog_start[] = {
|
|
BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
|
|
};
|
|
struct bpf_insn prog_end[] = {
|
|
BPF_MOV64_IMM(BPF_REG_0, 1), /* r0 = verdict */
|
|
BPF_EXIT_INSN(),
|
|
};
|
|
|
|
/* set sk_bound_dev_if on socket */
|
|
struct bpf_insn prog_dev[] = {
|
|
BPF_MOV64_IMM(BPF_REG_3, idx),
|
|
BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, bound_dev_if)),
|
|
BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, bound_dev_if)),
|
|
};
|
|
|
|
/* set mark on socket */
|
|
struct bpf_insn prog_mark[] = {
|
|
BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
|
|
BPF_MOV64_IMM(BPF_REG_3, mark),
|
|
BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, mark)),
|
|
BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, mark)),
|
|
};
|
|
|
|
/* set priority on socket */
|
|
struct bpf_insn prog_prio[] = {
|
|
BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
|
|
BPF_MOV64_IMM(BPF_REG_3, prio),
|
|
BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, priority)),
|
|
BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, priority)),
|
|
};
|
|
|
|
struct bpf_insn *prog;
|
|
size_t insns_cnt;
|
|
void *p;
|
|
int ret;
|
|
|
|
insns_cnt = sizeof(prog_start) + sizeof(prog_end);
|
|
if (idx)
|
|
insns_cnt += sizeof(prog_dev);
|
|
|
|
if (mark)
|
|
insns_cnt += sizeof(prog_mark);
|
|
|
|
if (prio)
|
|
insns_cnt += sizeof(prog_prio);
|
|
|
|
p = prog = malloc(insns_cnt);
|
|
if (!prog) {
|
|
fprintf(stderr, "Failed to allocate memory for instructions\n");
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
memcpy(p, prog_start, sizeof(prog_start));
|
|
p += sizeof(prog_start);
|
|
|
|
if (idx) {
|
|
memcpy(p, prog_dev, sizeof(prog_dev));
|
|
p += sizeof(prog_dev);
|
|
}
|
|
|
|
if (mark) {
|
|
memcpy(p, prog_mark, sizeof(prog_mark));
|
|
p += sizeof(prog_mark);
|
|
}
|
|
|
|
if (prio) {
|
|
memcpy(p, prog_prio, sizeof(prog_prio));
|
|
p += sizeof(prog_prio);
|
|
}
|
|
|
|
memcpy(p, prog_end, sizeof(prog_end));
|
|
p += sizeof(prog_end);
|
|
|
|
insns_cnt /= sizeof(struct bpf_insn);
|
|
|
|
ret = bpf_load_program(BPF_PROG_TYPE_CGROUP_SOCK, prog, insns_cnt,
|
|
"GPL", 0, bpf_log_buf, BPF_LOG_BUF_SIZE);
|
|
|
|
free(prog);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int usage(const char *argv0)
|
|
{
|
|
printf("Usage:\n");
|
|
printf(" Attach a program\n");
|
|
printf(" %s -b bind-to-dev -m mark -p prio cg-path\n", argv0);
|
|
printf("\n");
|
|
printf(" Detach a program\n");
|
|
printf(" %s -d cg-path\n", argv0);
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
__u32 idx = 0, mark = 0, prio = 0;
|
|
const char *cgrp_path = NULL;
|
|
int cg_fd, prog_fd, ret;
|
|
int do_attach = 1;
|
|
int rc;
|
|
|
|
while ((rc = getopt(argc, argv, "db:m:p:")) != -1) {
|
|
switch (rc) {
|
|
case 'd':
|
|
do_attach = 0;
|
|
break;
|
|
case 'b':
|
|
idx = if_nametoindex(optarg);
|
|
if (!idx) {
|
|
idx = strtoumax(optarg, NULL, 0);
|
|
if (!idx) {
|
|
printf("Invalid device name\n");
|
|
return EXIT_FAILURE;
|
|
}
|
|
}
|
|
break;
|
|
case 'm':
|
|
mark = strtoumax(optarg, NULL, 0);
|
|
break;
|
|
case 'p':
|
|
prio = strtoumax(optarg, NULL, 0);
|
|
break;
|
|
default:
|
|
return usage(argv[0]);
|
|
}
|
|
}
|
|
|
|
if (optind == argc)
|
|
return usage(argv[0]);
|
|
|
|
cgrp_path = argv[optind];
|
|
if (!cgrp_path) {
|
|
fprintf(stderr, "cgroup path not given\n");
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
if (do_attach && !idx && !mark && !prio) {
|
|
fprintf(stderr,
|
|
"One of device, mark or priority must be given\n");
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
cg_fd = open(cgrp_path, O_DIRECTORY | O_RDONLY);
|
|
if (cg_fd < 0) {
|
|
printf("Failed to open cgroup path: '%s'\n", strerror(errno));
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
if (do_attach) {
|
|
prog_fd = prog_load(idx, mark, prio);
|
|
if (prog_fd < 0) {
|
|
printf("Failed to load prog: '%s'\n", strerror(errno));
|
|
printf("Output from kernel verifier:\n%s\n-------\n",
|
|
bpf_log_buf);
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
ret = bpf_prog_attach(prog_fd, cg_fd,
|
|
BPF_CGROUP_INET_SOCK_CREATE, 0);
|
|
if (ret < 0) {
|
|
printf("Failed to attach prog to cgroup: '%s'\n",
|
|
strerror(errno));
|
|
return EXIT_FAILURE;
|
|
}
|
|
} else {
|
|
ret = bpf_prog_detach(cg_fd, BPF_CGROUP_INET_SOCK_CREATE);
|
|
if (ret < 0) {
|
|
printf("Failed to detach prog from cgroup: '%s'\n",
|
|
strerror(errno));
|
|
return EXIT_FAILURE;
|
|
}
|
|
}
|
|
|
|
close(cg_fd);
|
|
return EXIT_SUCCESS;
|
|
}
|