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Commit 42984d7c authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b2197755

samples/bpf/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -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

samples/bpf/fds_example.c

0 → 100644
+183 −0
Original line number Diff line number Diff line 
#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;

}

samples/bpf/libbpf.c

+19 −0
Original line number Diff line number Diff line
@@ -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;

samples/bpf/libbpf.h

+3 −0
Original line number Diff line number Diff line
@@ -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];