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 <dan...@iogearbox.net>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
samples/bpf/Makefile | 3 +
samples/bpf/fds_example.c | 183 ++++++++++++++++++++++++++++++++++++++++++++++
samples/bpf/libbpf.c | 19 +++++
samples/bpf/libbpf.h | 3 +
4 files changed, 208 insertions(+)
create mode 100644 samples/bpf/fds_example.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index b305145..79b4596 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -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
diff --git a/samples/bpf/fds_example.c b/samples/bpf/fds_example.c
new file mode 100644
index 0000000..e2fd16c
--- /dev/null
+++ b/samples/bpf/fds_example.c
@@ -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;
+}
diff --git a/samples/bpf/libbpf.c b/samples/bpf/libbpf.c
index 7e1efa7..65a8d48 100644
--- a/samples/bpf/libbpf.c
+++ b/samples/bpf/libbpf.c
@@ -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;
diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h
index b7f63c70..014aacf 100644
--- a/samples/bpf/libbpf.h
+++ b/samples/bpf/libbpf.h
@@ -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];
--
1.9.3
--
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