BPF tail call uses the BPF_MAP_TYPE_PROG_ARRAY type map for calling
into other BPF programs and this PROG_ARRAY should be filled prior to
use. Currently, samples with the PROG_ARRAY type MAP fill this program
array with bpf_load. For bpf_load to fill this map, kernel BPF program
must specify the section with specific format of <prog_type>/<array_idx>
(e.g. SEC("socket/0"))
But by using libbpf instead of bpf_load, user program can specify which
programs should be added to PROG_ARRAY. The advantage of this approach
is that you can selectively add only the programs you want, rather than
adding all of them to PROG_ARRAY, and it's much more intuitive than the
traditional approach.
This commit refactors user programs with the PROG_ARRAY type MAP with
libbpf instead of using bpf_load.
Signed-off-by: Daniel T. Lee <danieltimlee@xxxxxxxxx>
---
samples/bpf/Makefile | 4 +--
samples/bpf/sockex3_user.c | 66 ++++++++++++++++++++++++-----------
samples/bpf/tracex5_user.c | 70 +++++++++++++++++++++++++++++++++-----
3 files changed, 110 insertions(+), 30 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 4c91e5914329..8403e4762306 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -63,12 +63,12 @@ TRACE_HELPERS := ../../tools/testing/selftests/bpf/trace_helpers.o
fds_example-objs := fds_example.o
sockex1-objs := sockex1_user.o
sockex2-objs := sockex2_user.o
-sockex3-objs := bpf_load.o sockex3_user.o
+sockex3-objs := sockex3_user.o
tracex1-objs := tracex1_user.o $(TRACE_HELPERS)
tracex2-objs := tracex2_user.o
tracex3-objs := tracex3_user.o
tracex4-objs := tracex4_user.o
-tracex5-objs := bpf_load.o tracex5_user.o $(TRACE_HELPERS)
+tracex5-objs := tracex5_user.o $(TRACE_HELPERS)
tracex6-objs := tracex6_user.o
tracex7-objs := tracex7_user.o
test_probe_write_user-objs := bpf_load.o test_probe_write_user_user.o
diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c
index bbb1cd0666a9..961ae9c7deb9 100644
--- a/samples/bpf/sockex3_user.c
+++ b/samples/bpf/sockex3_user.c
@@ -1,17 +1,15 @@
// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <assert.h>
-#include <linux/bpf.h>
#include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
#include "sock_example.h"
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/resource.h>
-#define PARSE_IP 3
-#define PARSE_IP_PROG_FD (prog_fd[0])
-#define PROG_ARRAY_FD (map_fd[0])
+#define __must_check
+#include <linux/err.h>
struct flow_key_record {
__be32 src;
@@ -30,31 +28,56 @@ struct pair {
int main(int argc, char **argv)
{
+ int i, sock, key, fd, main_prog_fd, jmp_table_fd, hash_map_fd;
struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+ struct bpf_program *prog;
+ struct bpf_object *obj;
char filename[256];
+ const char *title;
FILE *f;
- int i, sock, err, id, key = PARSE_IP;
- struct bpf_prog_info info = {};
- uint32_t info_len = sizeof(info);
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
setrlimit(RLIMIT_MEMLOCK, &r);
- if (load_bpf_file(filename)) {
- printf("%s", bpf_log_buf);
- return 1;
+ obj = bpf_object__open_file(filename, NULL);
+ if (IS_ERR(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ obj = NULL;
+ goto cleanup;
}
- /* Test fd array lookup which returns the id of the bpf_prog */
- err = bpf_obj_get_info_by_fd(PARSE_IP_PROG_FD, &info, &info_len);
- assert(!err);
- err = bpf_map_lookup_elem(PROG_ARRAY_FD, &key, &id);
- assert(!err);
- assert(id == info.id);
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ jmp_table_fd = bpf_object__find_map_fd_by_name(obj, "jmp_table");
+ hash_map_fd = bpf_object__find_map_fd_by_name(obj, "hash_map");
+ if (jmp_table_fd < 0 || hash_map_fd < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
+ bpf_object__for_each_program(prog, obj) {
+ fd = bpf_program__fd(prog);
+
+ title = bpf_program__title(prog, false);
+ if (sscanf(title, "socket/%d", &key) != 1) {
+ fprintf(stderr, "ERROR: finding prog failed\n");
+ goto cleanup;
+ }
+
+ if (key == 0)
+ main_prog_fd = fd;
+ else
+ bpf_map_update_elem(jmp_table_fd, &key, &fd, BPF_ANY);
+ }
sock = open_raw_sock("lo");
- assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd[4],
+ /* attach BPF program to socket */
+ assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &main_prog_fd,
sizeof(__u32)) == 0);
if (argc > 1)
@@ -69,8 +92,8 @@ int main(int argc, char **argv)
sleep(1);
printf("IP src.port -> dst.port bytes packets\n");
- while (bpf_map_get_next_key(map_fd[2], &key, &next_key) == 0) {
- bpf_map_lookup_elem(map_fd[2], &next_key, &value);
+ while (bpf_map_get_next_key(hash_map_fd, &key, &next_key) == 0) {
+ bpf_map_lookup_elem(hash_map_fd, &next_key, &value);
printf("%s.%05d -> %s.%05d %12lld %12lld\n",
inet_ntoa((struct in_addr){htonl(next_key.src)}),
next_key.port16[0],
@@ -80,5 +103,8 @@ int main(int argc, char **argv)
key = next_key;
}
}
+
+cleanup:
+ bpf_object__close(obj);
return 0;
}
diff --git a/samples/bpf/tracex5_user.c b/samples/bpf/tracex5_user.c
index c2317b39e0d2..a88b234fac32 100644
--- a/samples/bpf/tracex5_user.c
+++ b/samples/bpf/tracex5_user.c
@@ -1,15 +1,24 @@
// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
-#include <linux/bpf.h>
+#include <stdlib.h>
#include <unistd.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
#include <sys/prctl.h>
#include <bpf/bpf.h>
-#include "bpf_load.h"
+#include <bpf/libbpf.h>
#include <sys/resource.h>
#include "trace_helpers.h"
+#define __must_check
+#include <linux/err.h>
+
+#ifdef __mips__
+#define MAX_ENTRIES 6000 /* MIPS n64 syscalls start at 5000 */
+#else
+#define MAX_ENTRIES 1024
+#endif
+
/* install fake seccomp program to enable seccomp code path inside the kernel,
* so that our kprobe attached to seccomp_phase1() can be triggered
*/
@@ -28,16 +37,58 @@ static void install_accept_all_seccomp(void)
int main(int ac, char **argv)
{
- FILE *f;
- char filename[256];
struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+ struct bpf_link *link = NULL;
+ struct bpf_program *prog;
+ struct bpf_object *obj;
+ int key, fd, progs_fd;
+ char filename[256];
+ const char *title;
+ FILE *f;
- snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
setrlimit(RLIMIT_MEMLOCK, &r);
- if (load_bpf_file(filename)) {
- printf("%s", bpf_log_buf);
- return 1;
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ obj = bpf_object__open_file(filename, NULL);
+ if (IS_ERR(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ obj = NULL;
+ goto cleanup;
+ }
+
+ prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
+ if (!prog) {
+ printf("finding a prog in obj file failed\n");
+ goto cleanup;
+ }
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ link = bpf_program__attach(prog);
+ if (IS_ERR(link)) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ link = NULL;
+ goto cleanup;
+ }
+
+ progs_fd = bpf_object__find_map_fd_by_name(obj, "progs");
+ if (progs_fd < 0) {
+ fprintf(stderr, "ERROR: finding a map in obj file failed\n");
+ goto cleanup;
+ }
+
+ bpf_object__for_each_program(prog, obj) {
+ title = bpf_program__title(prog, false);
+ /* register only syscalls to PROG_ARRAY */
+ if (sscanf(title, "kprobe/%d", &key) != 1)
+ continue;
+
+ fd = bpf_program__fd(prog);
+ bpf_map_update_elem(progs_fd, &key, &fd, BPF_ANY);
}
install_accept_all_seccomp();
@@ -47,5 +98,8 @@ int main(int ac, char **argv)
read_trace_pipe();
+cleanup:
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
return 0;
}
--
2.25.1
