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author | Daniel T. Lee <danieltimlee@gmail.com> | 2020-05-16 13:06:06 +0900 |
---|---|---|
committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-05-19 17:12:56 +0200 |
commit | bc1a85977b950407d67cd1e5b74f261a4bee3284 (patch) | |
tree | e4c5283ae3815b08fe2a09a34576a7ebf7931ecf /samples | |
parent | 63841bc0833623ecd4f758ec055b543cf1bc56ba (diff) | |
download | lwn-bc1a85977b950407d67cd1e5b74f261a4bee3284.tar.gz lwn-bc1a85977b950407d67cd1e5b74f261a4bee3284.zip |
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 <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@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200516040608.1377876-4-danieltimlee@gmail.com
Diffstat (limited to 'samples')
-rw-r--r-- | samples/bpf/Makefile | 4 | ||||
-rw-r--r-- | samples/bpf/sockex3_user.c | 64 | ||||
-rw-r--r-- | samples/bpf/tracex5_user.c | 66 |
3 files changed, 103 insertions, 31 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..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 <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]) - 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; } diff --git a/samples/bpf/tracex5_user.c b/samples/bpf/tracex5_user.c index c2317b39e0d2..98dad57a96c4 100644 --- a/samples/bpf/tracex5_user.c +++ b/samples/bpf/tracex5_user.c @@ -1,15 +1,21 @@ // 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" +#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 +34,57 @@ 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 (libbpf_get_error(obj)) { + fprintf(stderr, "ERROR: opening BPF object file failed\n"); + return 0; + } + + 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 (libbpf_get_error(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 +94,8 @@ int main(int ac, char **argv) read_trace_pipe(); +cleanup: + bpf_link__destroy(link); + bpf_object__close(obj); return 0; } |