From bc1a85977b950407d67cd1e5b74f261a4bee3284 Mon Sep 17 00:00:00 2001 From: "Daniel T. Lee" Date: Sat, 16 May 2020 13:06:06 +0900 Subject: samples, bpf: Refactor tail call user progs with libbpf 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 / (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 Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200516040608.1377876-4-danieltimlee@gmail.com --- samples/bpf/sockex3_user.c | 64 +++++++++++++++++++++++++++++++--------------- 1 file changed, 43 insertions(+), 21 deletions(-) (limited to 'samples/bpf/sockex3_user.c') diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c index bbb1cd0666a9..4dbee7427d47 100644 --- a/samples/bpf/sockex3_user.c +++ b/samples/bpf/sockex3_user.c @@ -1,18 +1,13 @@ // SPDX-License-Identifier: GPL-2.0 #include #include -#include #include -#include "bpf_load.h" +#include #include "sock_example.h" #include #include #include -#define PARSE_IP 3 -#define PARSE_IP_PROG_FD (prog_fd[0]) -#define PROG_ARRAY_FD (map_fd[0]) - struct flow_key_record { __be32 src; __be32 dst; @@ -30,31 +25,55 @@ 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 (libbpf_get_error(obj)) { + fprintf(stderr, "ERROR: opening BPF object file failed\n"); + return 0; + } + + /* 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; } - /* 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); + 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 +88,8 @@ 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 +99,8 @@ int main(int argc, char **argv) key = next_key; } } + +cleanup: + bpf_object__close(obj); return 0; } -- cgit v1.2.3-59-g8ed1b