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bpf: add sample usages for persistent maps/progs 

This patch adds a couple of stand-alone examples on how BPF_OBJ_PIN
and BPF_OBJ_GET commands can be used.

Example with maps:

  # ./fds_example -F /sys/fs/bpf/m -P -m -k 1 -v 42
  bpf: map fd:3 (Success)
  bpf: pin ret:(0,Success)
  bpf: fd:3 u->(1:42) ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/m -G -m -k 1
  bpf: get fd:3 (Success)
  bpf: fd:3 l->(1):42 ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/m -G -m -k 1 -v 24
  bpf: get fd:3 (Success)
  bpf: fd:3 u->(1:24) ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/m -G -m -k 1
  bpf: get fd:3 (Success)
  bpf: fd:3 l->(1):24 ret:(0,Success)

  # ./fds_example -F /sys/fs/bpf/m2 -P -m
  bpf: map fd:3 (Success)
  bpf: pin ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/m2 -G -m -k 1
  bpf: get fd:3 (Success)
  bpf: fd:3 l->(1):0 ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/m2 -G -m
  bpf: get fd:3 (Success)

Example with progs:

  # ./fds_example -F /sys/fs/bpf/p -P -p
  bpf: prog fd:3 (Success)
  bpf: pin ret:(0,Success)
  bpf sock:4 <- fd:3 attached ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/p -G -p
  bpf: get fd:3 (Success)
  bpf: sock:4 <- fd:3 attached ret:(0,Success)

  # ./fds_example -F /sys/fs/bpf/p2 -P -p -o ./sockex1_kern.o
  bpf: prog fd:5 (Success)
  bpf: pin ret:(0,Success)
  bpf: sock:3 <- fd:5 attached ret:(0,Success)
  # ./fds_example -F /sys/fs/bpf/p2 -G -p
  bpf: get fd:3 (Success)
  bpf: sock:4 <- fd:3 attached ret:(0,Success)

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Daniel Borkmann 2015-10-29 14:58:10 +01:00 committed by David S. Miller
parent b2197755b2
commit 42984d7c1e
4 changed files with 208 additions and 0 deletions
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3
samples/bpf/Makefile
View File

@ -4,6 +4,7 @@ obj- := dummy.o
# List of programs to build
hostprogs-y := test_verifier test_maps
hostprogs-y += sock_example
hostprogs-y += fds_example
hostprogs-y += sockex1
hostprogs-y += sockex2
hostprogs-y += sockex3
@ -19,6 +20,7 @@ hostprogs-y += lathist
test_verifier-objs := test_verifier.o libbpf.o
test_maps-objs := test_maps.o libbpf.o
sock_example-objs := sock_example.o libbpf.o
fds_example-objs := bpf_load.o libbpf.o fds_example.o
sockex1-objs := bpf_load.o libbpf.o sockex1_user.o
sockex2-objs := bpf_load.o libbpf.o sockex2_user.o
sockex3-objs := bpf_load.o libbpf.o sockex3_user.o
@ -49,6 +51,7 @@ always += lathist_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable
HOSTLOADLIBES_fds_example += -lelf
HOSTLOADLIBES_sockex1 += -lelf
HOSTLOADLIBES_sockex2 += -lelf
HOSTLOADLIBES_sockex3 += -lelf

183
samples/bpf/fds_example.c 100644
View File

@ -0,0 +1,183 @@
#include <linux/unistd.h>
#include <linux/bpf.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "bpf_load.h"
#include "libbpf.h"
#define BPF_F_PIN (1 << 0)
#define BPF_F_GET (1 << 1)
#define BPF_F_PIN_GET (BPF_F_PIN | BPF_F_GET)
#define BPF_F_KEY (1 << 2)
#define BPF_F_VAL (1 << 3)
#define BPF_F_KEY_VAL (BPF_F_KEY | BPF_F_VAL)
#define BPF_M_UNSPEC 0
#define BPF_M_MAP 1
#define BPF_M_PROG 2
static void usage(void)
{
printf("Usage: fds_example [...]\n");
printf(" -F <file> File to pin/get object\n");
printf(" -P |- pin object\n");
printf(" -G `- get object\n");
printf(" -m eBPF map mode\n");
printf(" -k <key> |- map key\n");
printf(" -v <value> `- map value\n");
printf(" -p eBPF prog mode\n");
printf(" -o <object> `- object file\n");
printf(" -h Display this help.\n");
}
static int bpf_map_create(void)
{
return bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(uint32_t),
sizeof(uint32_t), 1024);
}
static int bpf_prog_create(const char *object)
{
static const struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 1),
BPF_EXIT_INSN(),
};
if (object) {
assert(!load_bpf_file((char *)object));
return prog_fd[0];
} else {
return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER,
insns, sizeof(insns), "GPL", 0);
}
}
static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
uint32_t value)
{
int fd, ret;
if (flags & BPF_F_PIN) {
fd = bpf_map_create();
printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
assert(fd > 0);
ret = bpf_obj_pin(fd, file);
printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
assert(ret == 0);
} else {
fd = bpf_obj_get(file);
printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
assert(fd > 0);
}
if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
ret = bpf_update_elem(fd, &key, &value, 0);
printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
ret, strerror(errno));
assert(ret == 0);
} else if (flags & BPF_F_KEY) {
ret = bpf_lookup_elem(fd, &key, &value);
printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
ret, strerror(errno));
assert(ret == 0);
}
return 0;
}
static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
{
int fd, sock, ret;
if (flags & BPF_F_PIN) {
fd = bpf_prog_create(object);
printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
assert(fd > 0);
ret = bpf_obj_pin(fd, file);
printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
assert(ret == 0);
} else {
fd = bpf_obj_get(file);
printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
assert(fd > 0);
}
sock = open_raw_sock("lo");
assert(sock > 0);
ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
ret, strerror(errno));
assert(ret == 0);
return 0;
}
int main(int argc, char **argv)
{
const char *file = NULL, *object = NULL;
uint32_t key = 0, value = 0, flags = 0;
int opt, mode = BPF_M_UNSPEC;
while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
switch (opt) {
/* General args */
case 'F':
file = optarg;
break;
case 'P':
flags |= BPF_F_PIN;
break;
case 'G':
flags |= BPF_F_GET;
break;
/* Map-related args */
case 'm':
mode = BPF_M_MAP;
break;
case 'k':
key = strtoul(optarg, NULL, 0);
flags |= BPF_F_KEY;
break;
case 'v':
value = strtoul(optarg, NULL, 0);
flags |= BPF_F_VAL;
break;
/* Prog-related args */
case 'p':
mode = BPF_M_PROG;
break;
case 'o':
object = optarg;
break;
default:
goto out;
}
}
if (!(flags & BPF_F_PIN_GET) || !file)
goto out;
switch (mode) {
case BPF_M_MAP:
return bpf_do_map(file, flags, key, value);
case BPF_M_PROG:
return bpf_do_prog(file, flags, object);
}
out:
usage();
return -1;
}

19
samples/bpf/libbpf.c
View File

@ -103,6 +103,25 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
}
int bpf_obj_pin(int fd, const char *pathname)
{
union bpf_attr attr = {
.pathname = ptr_to_u64((void *)pathname),
.bpf_fd = fd,
};
return syscall(__NR_bpf, BPF_OBJ_PIN, &attr, sizeof(attr));
}
int bpf_obj_get(const char *pathname)
{
union bpf_attr attr = {
.pathname = ptr_to_u64((void *)pathname),
};
return syscall(__NR_bpf, BPF_OBJ_GET, &attr, sizeof(attr));
}
int open_raw_sock(const char *name)
{
struct sockaddr_ll sll;

3
samples/bpf/libbpf.h
View File

@ -15,6 +15,9 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, int insn_len,
const char *license, int kern_version);
int bpf_obj_pin(int fd, const char *pathname);
int bpf_obj_get(const char *pathname);
#define LOG_BUF_SIZE 65536
extern char bpf_log_buf[LOG_BUF_SIZE];