samples/bpf/fds_example.c

0001 #include <linux/unistd.h>
0002 #include <linux/bpf.h>
0003
0004 #include <stdio.h>
0005 #include <stdlib.h>
0006 #include <stdint.h>
0007 #include <unistd.h>
0008 #include <string.h>
0009 #include <assert.h>
0010 #include <errno.h>
0011
0012 #include <sys/types.h>
0013 #include <sys/socket.h>
0014
0015 #include <bpf/bpf.h>
0016
0017 #include <bpf/libbpf.h>
0018 #include "bpf_insn.h"
0019 #include "sock_example.h"
0020 #include "bpf_util.h"
0021
0022 #define BPF_F_PIN   (1 << 0)
0023 #define BPF_F_GET   (1 << 1)
0024 #define BPF_F_PIN_GET   (BPF_F_PIN | BPF_F_GET)
0025
0026 #define BPF_F_KEY   (1 << 2)
0027 #define BPF_F_VAL   (1 << 3)
0028 #define BPF_F_KEY_VAL   (BPF_F_KEY | BPF_F_VAL)
0029
0030 #define BPF_M_UNSPEC    0
0031 #define BPF_M_MAP   1
0032 #define BPF_M_PROG  2
0033
0034 char bpf_log_buf[BPF_LOG_BUF_SIZE];
0035
0036 static void usage(void)
0037 {
0038     printf("Usage: fds_example [...]\n");
0039     printf("       -F <file>   File to pin/get object\n");
0040     printf("       -P          |- pin object\n");
0041     printf("       -G          `- get object\n");
0042     printf("       -m          eBPF map mode\n");
0043     printf("       -k <key>    |- map key\n");
0044     printf("       -v <value>  `- map value\n");
0045     printf("       -p          eBPF prog mode\n");
0046     printf("       -o <object> `- object file\n");
0047     printf("       -h          Display this help.\n");
0048 }
0049
0050 static int bpf_prog_create(const char *object)
0051 {
0052     static struct bpf_insn insns[] = {
0053         BPF_MOV64_IMM(BPF_REG_0, 1),
0054         BPF_EXIT_INSN(),
0055     };
0056     size_t insns_cnt = ARRAY_SIZE(insns);
0057     struct bpf_object *obj;
0058     int err;
0059
0060     if (object) {
0061         obj = bpf_object__open_file(object, NULL);
0062         assert(!libbpf_get_error(obj));
0063         err = bpf_object__load(obj);
0064         assert(!err);
0065         return bpf_program__fd(bpf_object__next_program(obj, NULL));
0066     } else {
0067         LIBBPF_OPTS(bpf_prog_load_opts, opts,
0068             .log_buf = bpf_log_buf,
0069             .log_size = BPF_LOG_BUF_SIZE,
0070         );
0071
0072         return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
0073                      insns, insns_cnt, &opts);
0074     }
0075 }
0076
0077 static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
0078               uint32_t value)
0079 {
0080     int fd, ret;
0081
0082     if (flags & BPF_F_PIN) {
0083         fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(uint32_t),
0084                     sizeof(uint32_t), 1024, NULL);
0085         printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
0086         assert(fd > 0);
0087
0088         ret = bpf_obj_pin(fd, file);
0089         printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
0090         assert(ret == 0);
0091     } else {
0092         fd = bpf_obj_get(file);
0093         printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
0094         assert(fd > 0);
0095     }
0096
0097     if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
0098         ret = bpf_map_update_elem(fd, &key, &value, 0);
0099         printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
0100                ret, strerror(errno));
0101         assert(ret == 0);
0102     } else if (flags & BPF_F_KEY) {
0103         ret = bpf_map_lookup_elem(fd, &key, &value);
0104         printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
0105                ret, strerror(errno));
0106         assert(ret == 0);
0107     }
0108
0109     return 0;
0110 }
0111
0112 static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
0113 {
0114     int fd, sock, ret;
0115
0116     if (flags & BPF_F_PIN) {
0117         fd = bpf_prog_create(object);
0118         printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
0119         assert(fd > 0);
0120
0121         ret = bpf_obj_pin(fd, file);
0122         printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
0123         assert(ret == 0);
0124     } else {
0125         fd = bpf_obj_get(file);
0126         printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
0127         assert(fd > 0);
0128     }
0129
0130     sock = open_raw_sock("lo");
0131     assert(sock > 0);
0132
0133     ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
0134     printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
0135            ret, strerror(errno));
0136     assert(ret == 0);
0137
0138     return 0;
0139 }
0140
0141 int main(int argc, char **argv)
0142 {
0143     const char *file = NULL, *object = NULL;
0144     uint32_t key = 0, value = 0, flags = 0;
0145     int opt, mode = BPF_M_UNSPEC;
0146
0147     while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
0148         switch (opt) {
0149         /* General args */
0150         case 'F':
0151             file = optarg;
0152             break;
0153         case 'P':
0154             flags |= BPF_F_PIN;
0155             break;
0156         case 'G':
0157             flags |= BPF_F_GET;
0158             break;
0159         /* Map-related args */
0160         case 'm':
0161             mode = BPF_M_MAP;
0162             break;
0163         case 'k':
0164             key = strtoul(optarg, NULL, 0);
0165             flags |= BPF_F_KEY;
0166             break;
0167         case 'v':
0168             value = strtoul(optarg, NULL, 0);
0169             flags |= BPF_F_VAL;
0170             break;
0171         /* Prog-related args */
0172         case 'p':
0173             mode = BPF_M_PROG;
0174             break;
0175         case 'o':
0176             object = optarg;
0177             break;
0178         default:
0179             goto out;
0180         }
0181     }
0182
0183     if (!(flags & BPF_F_PIN_GET) || !file)
0184         goto out;
0185
0186     switch (mode) {
0187     case BPF_M_MAP:
0188         return bpf_do_map(file, flags, key, value);
0189     case BPF_M_PROG:
0190         return bpf_do_prog(file, flags, object);
0191     }
0192 out:
0193     usage();
0194     return -1;
0195 }