135 lines · c
1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2022 Red Hat */3#include <test_progs.h>4#include <bpf/btf.h>5#include "bpf/libbpf_internal.h"6#include "cgroup_helpers.h"7#include "bpf_util.h"8 9static const char *module_name = "bpf_testmod";10static const char *symbol_name = "bpf_fentry_shadow_test";11 12static int get_bpf_testmod_btf_fd(void)13{14 struct bpf_btf_info info;15 char name[64];16 __u32 id = 0, len;17 int err, fd;18 19 while (true) {20 err = bpf_btf_get_next_id(id, &id);21 if (err) {22 log_err("failed to iterate BTF objects");23 return err;24 }25 26 fd = bpf_btf_get_fd_by_id(id);27 if (fd < 0) {28 if (errno == ENOENT)29 continue; /* expected race: BTF was unloaded */30 err = -errno;31 log_err("failed to get FD for BTF object #%d", id);32 return err;33 }34 35 len = sizeof(info);36 memset(&info, 0, sizeof(info));37 info.name = ptr_to_u64(name);38 info.name_len = sizeof(name);39 40 err = bpf_obj_get_info_by_fd(fd, &info, &len);41 if (err) {42 err = -errno;43 log_err("failed to get info for BTF object #%d", id);44 close(fd);45 return err;46 }47 48 if (strcmp(name, module_name) == 0)49 return fd;50 51 close(fd);52 }53 return -ENOENT;54}55 56void test_module_fentry_shadow(void)57{58 struct btf *vmlinux_btf = NULL, *mod_btf = NULL;59 int err, i;60 int btf_fd[2] = {};61 int prog_fd[2] = {};62 int link_fd[2] = {};63 __s32 btf_id[2] = {};64 65 if (!env.has_testmod) {66 test__skip();67 return;68 }69 70 LIBBPF_OPTS(bpf_prog_load_opts, load_opts,71 .expected_attach_type = BPF_TRACE_FENTRY,72 );73 74 const struct bpf_insn trace_program[] = {75 BPF_MOV64_IMM(BPF_REG_0, 0),76 BPF_EXIT_INSN(),77 };78 79 vmlinux_btf = btf__load_vmlinux_btf();80 if (!ASSERT_OK_PTR(vmlinux_btf, "load_vmlinux_btf"))81 return;82 83 btf_fd[1] = get_bpf_testmod_btf_fd();84 if (!ASSERT_GE(btf_fd[1], 0, "get_bpf_testmod_btf_fd"))85 goto out;86 87 mod_btf = btf_get_from_fd(btf_fd[1], vmlinux_btf);88 if (!ASSERT_OK_PTR(mod_btf, "btf_get_from_fd"))89 goto out;90 91 btf_id[0] = btf__find_by_name_kind(vmlinux_btf, symbol_name, BTF_KIND_FUNC);92 if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name"))93 goto out;94 95 btf_id[1] = btf__find_by_name_kind(mod_btf, symbol_name, BTF_KIND_FUNC);96 if (!ASSERT_GT(btf_id[1], 0, "btf_find_by_name"))97 goto out;98 99 for (i = 0; i < 2; i++) {100 load_opts.attach_btf_id = btf_id[i];101 load_opts.attach_btf_obj_fd = btf_fd[i];102 prog_fd[i] = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL",103 trace_program,104 ARRAY_SIZE(trace_program),105 &load_opts);106 if (!ASSERT_GE(prog_fd[i], 0, "bpf_prog_load"))107 goto out;108 109 /* If the verifier incorrectly resolves addresses of the110 * shadowed functions and uses the same address for both the111 * vmlinux and the bpf_testmod functions, this will fail on112 * attempting to create two trampolines for the same address,113 * which is forbidden.114 */115 link_fd[i] = bpf_link_create(prog_fd[i], 0, BPF_TRACE_FENTRY, NULL);116 if (!ASSERT_GE(link_fd[i], 0, "bpf_link_create"))117 goto out;118 }119 120 err = bpf_prog_test_run_opts(prog_fd[0], NULL);121 ASSERT_OK(err, "running test");122 123out:124 btf__free(vmlinux_btf);125 btf__free(mod_btf);126 for (i = 0; i < 2; i++) {127 if (btf_fd[i])128 close(btf_fd[i]);129 if (prog_fd[i] > 0)130 close(prog_fd[i]);131 if (link_fd[i] > 0)132 close(link_fd[i]);133 }134}135