diff options
Diffstat (limited to 'samples/bpf/test_cgrp2_attach.c')
| -rw-r--r-- | samples/bpf/test_cgrp2_attach.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/samples/bpf/test_cgrp2_attach.c b/samples/bpf/test_cgrp2_attach.c new file mode 100644 index 000000000000..a19484c45b79 --- /dev/null +++ b/samples/bpf/test_cgrp2_attach.c @@ -0,0 +1,167 @@ +/* eBPF example program: + * + * - Creates arraymap in kernel with 4 bytes keys and 8 byte values + * + * - Loads eBPF program + * + * The eBPF program accesses the map passed in to store two pieces of + * information. The number of invocations of the program, which maps + * to the number of packets received, is stored to key 0. Key 1 is + * incremented on each iteration by the number of bytes stored in + * the skb. + * + * - Attaches the new program to a cgroup using BPF_PROG_ATTACH + * + * - Every second, reads map[0] and map[1] to see how many bytes and + * packets were seen on any socket of tasks in the given cgroup. + */ + +#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 <linux/bpf.h> + +#include "libbpf.h" + +enum { + MAP_KEY_PACKETS, + MAP_KEY_BYTES, +}; + +static int prog_load(int map_fd, int verdict) +{ + struct bpf_insn prog[] = { + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), /* save r6 so it's not clobbered by BPF_CALL */ + + /* Count packets */ + BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_PACKETS), /* r0 = 0 */ + BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ + BPF_LD_MAP_FD(BPF_REG_1, map_fd), /* load map fd to r1 */ + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */ + BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */ + + /* Count bytes */ + BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_BYTES), /* r0 = 1 */ + BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ + BPF_LD_MAP_FD(BPF_REG_1, map_fd), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, offsetof(struct __sk_buff, len)), /* r1 = skb->len */ + BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */ + + BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */ + BPF_EXIT_INSN(), + }; + + return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SKB, + prog, sizeof(prog), "GPL", 0); +} + +static int usage(const char *argv0) +{ + printf("Usage: %s [-d] [-D] <cg-path> <egress|ingress>\n", argv0); + printf(" -d Drop Traffic\n"); + printf(" -D Detach filter, and exit\n"); + return EXIT_FAILURE; +} + +static int attach_filter(int cg_fd, int type, int verdict) +{ + int prog_fd, map_fd, ret, key; + long long pkt_cnt, byte_cnt; + + map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, + sizeof(key), sizeof(byte_cnt), + 256, 0); + if (map_fd < 0) { + printf("Failed to create map: '%s'\n", strerror(errno)); + return EXIT_FAILURE; + } + + prog_fd = prog_load(map_fd, verdict); + printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf); + + if (prog_fd < 0) { + printf("Failed to load prog: '%s'\n", strerror(errno)); + return EXIT_FAILURE; + } + + ret = bpf_prog_attach(prog_fd, cg_fd, type); + if (ret < 0) { + printf("Failed to attach prog to cgroup: '%s'\n", + strerror(errno)); + return EXIT_FAILURE; + } + while (1) { + key = MAP_KEY_PACKETS; + assert(bpf_lookup_elem(map_fd, &key, &pkt_cnt) == 0); + + key = MAP_KEY_BYTES; + assert(bpf_lookup_elem(map_fd, &key, &byte_cnt) == 0); + + printf("cgroup received %lld packets, %lld bytes\n", + pkt_cnt, byte_cnt); + sleep(1); + } + + return EXIT_SUCCESS; +} + +int main(int argc, char **argv) +{ + int detach_only = 0, verdict = 1; + enum bpf_attach_type type; + int opt, cg_fd, ret; + + while ((opt = getopt(argc, argv, "Dd")) != -1) { + switch (opt) { + case 'd': + verdict = 0; + break; + case 'D': + detach_only = 1; + break; + default: + return usage(argv[0]); + } + } + + if (argc - optind < 2) + return usage(argv[0]); + + if (strcmp(argv[optind + 1], "ingress") == 0) + type = BPF_CGROUP_INET_INGRESS; + else if (strcmp(argv[optind + 1], "egress") == 0) + type = BPF_CGROUP_INET_EGRESS; + else + return usage(argv[0]); + + cg_fd = open(argv[optind], O_DIRECTORY | O_RDONLY); + if (cg_fd < 0) { + printf("Failed to open cgroup path: '%s'\n", strerror(errno)); + return EXIT_FAILURE; + } + + if (detach_only) { + ret = bpf_prog_detach(cg_fd, type); + printf("bpf_prog_detach() returned '%s' (%d)\n", + strerror(errno), errno); + } else + ret = attach_filter(cg_fd, type, verdict); + + return ret; +} |