From d6f39601ec5e708fb666a2ad437c7bef4cfab39b Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 14 Nov 2019 10:57:20 -0800 Subject: selftests/bpf: Add a test for attaching BPF prog to another BPF prog and subprog Add a test that attaches one FEXIT program to main sched_cls networking program and two other FEXIT programs to subprograms. All three tracing programs access return values and skb->len of networking program and subprograms. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191114185720.1641606-21-ast@kernel.org --- .../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 76 ++++++++++++++++++ tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c | 91 ++++++++++++++++++++++ 2 files changed, 167 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c create mode 100644 tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c new file mode 100644 index 000000000000..15c7378362dd --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ +#include + +#define PROG_CNT 3 + +void test_fexit_bpf2bpf(void) +{ + const char *prog_name[PROG_CNT] = { + "fexit/test_pkt_access", + "fexit/test_pkt_access_subprog1", + "fexit/test_pkt_access_subprog2", + }; + struct bpf_object *obj = NULL, *pkt_obj; + int err, pkt_fd, i; + struct bpf_link *link[PROG_CNT] = {}; + struct bpf_program *prog[PROG_CNT]; + __u32 duration, retval; + struct bpf_map *data_map; + const int zero = 0; + u64 result[PROG_CNT]; + + err = bpf_prog_load("./test_pkt_access.o", BPF_PROG_TYPE_UNSPEC, + &pkt_obj, &pkt_fd); + if (CHECK(err, "prog_load sched cls", "err %d errno %d\n", err, errno)) + return; + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, + .attach_prog_fd = pkt_fd, + ); + + obj = bpf_object__open_file("./fexit_bpf2bpf.o", &opts); + if (CHECK(IS_ERR_OR_NULL(obj), "obj_open", + "failed to open fexit_bpf2bpf: %ld\n", + PTR_ERR(obj))) + goto close_prog; + + err = bpf_object__load(obj); + if (CHECK(err, "obj_load", "err %d\n", err)) + goto close_prog; + + for (i = 0; i < PROG_CNT; i++) { + prog[i] = bpf_object__find_program_by_title(obj, prog_name[i]); + if (CHECK(!prog[i], "find_prog", "prog %s not found\n", prog_name[i])) + goto close_prog; + link[i] = bpf_program__attach_trace(prog[i]); + if (CHECK(IS_ERR(link[i]), "attach_trace", "failed to link\n")) + goto close_prog; + } + data_map = bpf_object__find_map_by_name(obj, "fexit_bp.bss"); + if (CHECK(!data_map, "find_data_map", "data map not found\n")) + goto close_prog; + + err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6), + NULL, NULL, &retval, &duration); + CHECK(err || retval, "ipv6", + "err %d errno %d retval %d duration %d\n", + err, errno, retval, duration); + + err = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, &result); + if (CHECK(err, "get_result", + "failed to get output data: %d\n", err)) + goto close_prog; + + for (i = 0; i < PROG_CNT; i++) + if (CHECK(result[i] != 1, "result", "fexit_bpf2bpf failed err %ld\n", + result[i])) + goto close_prog; + +close_prog: + for (i = 0; i < PROG_CNT; i++) + if (!IS_ERR_OR_NULL(link[i])) + bpf_link__destroy(link[i]); + if (!IS_ERR_OR_NULL(obj)) + bpf_object__close(obj); + bpf_object__close(pkt_obj); +} diff --git a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c new file mode 100644 index 000000000000..981f0474da5a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ +#include +#include "bpf_helpers.h" + +struct sk_buff { + unsigned int len; +}; + +struct args { + struct sk_buff *skb; + ks32 ret; +}; +static volatile __u64 test_result; +SEC("fexit/test_pkt_access") +int test_main(struct args *ctx) +{ + struct sk_buff *skb = ctx->skb; + int len; + + __builtin_preserve_access_index(({ + len = skb->len; + })); + if (len != 74 || ctx->ret != 0) + return 0; + test_result = 1; + return 0; +} + +struct args_subprog1 { + struct sk_buff *skb; + ks32 ret; +}; +static volatile __u64 test_result_subprog1; +SEC("fexit/test_pkt_access_subprog1") +int test_subprog1(struct args_subprog1 *ctx) +{ + struct sk_buff *skb = ctx->skb; + int len; + + __builtin_preserve_access_index(({ + len = skb->len; + })); + if (len != 74 || ctx->ret != 148) + return 0; + test_result_subprog1 = 1; + return 0; +} + +/* Though test_pkt_access_subprog2() is defined in C as: + * static __attribute__ ((noinline)) + * int test_pkt_access_subprog2(int val, volatile struct __sk_buff *skb) + * { + * return skb->len * val; + * } + * llvm optimizations remove 'int val' argument and generate BPF assembly: + * r0 = *(u32 *)(r1 + 0) + * w0 <<= 1 + * exit + * In such case the verifier falls back to conservative and + * tracing program can access arguments and return value as u64 + * instead of accurate types. + */ +struct args_subprog2 { + ku64 args[5]; + ku64 ret; +}; +static volatile __u64 test_result_subprog2; +SEC("fexit/test_pkt_access_subprog2") +int test_subprog2(struct args_subprog2 *ctx) +{ + struct sk_buff *skb = (void *)ctx->args[0]; + __u64 ret; + int len; + + bpf_probe_read_kernel(&len, sizeof(len), + __builtin_preserve_access_index(&skb->len)); + + ret = ctx->ret; + /* bpf_prog_load() loads "test_pkt_access.o" with BPF_F_TEST_RND_HI32 + * which randomizes upper 32 bits after BPF_ALU32 insns. + * Hence after 'w0 <<= 1' upper bits of $rax are random. + * That is expected and correct. Trim them. + */ + ret = (__u32) ret; + if (len != 74 || ret != 148) + return 0; + test_result_subprog2 = 1; + return 0; +} +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3