129 lines
3.1 KiB
C
129 lines
3.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Red Hat */
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#include <test_progs.h>
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#include <bpf/btf.h>
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#include "bpf/libbpf_internal.h"
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#include "cgroup_helpers.h"
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static const char *module_name = "bpf_testmod";
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static const char *symbol_name = "bpf_fentry_shadow_test";
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static int get_bpf_testmod_btf_fd(void)
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{
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struct bpf_btf_info info;
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char name[64];
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__u32 id = 0, len;
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int err, fd;
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while (true) {
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err = bpf_btf_get_next_id(id, &id);
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if (err) {
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log_err("failed to iterate BTF objects");
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return err;
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}
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fd = bpf_btf_get_fd_by_id(id);
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if (fd < 0) {
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if (errno == ENOENT)
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continue; /* expected race: BTF was unloaded */
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err = -errno;
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log_err("failed to get FD for BTF object #%d", id);
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return err;
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}
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len = sizeof(info);
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memset(&info, 0, sizeof(info));
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info.name = ptr_to_u64(name);
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info.name_len = sizeof(name);
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err = bpf_obj_get_info_by_fd(fd, &info, &len);
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if (err) {
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err = -errno;
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log_err("failed to get info for BTF object #%d", id);
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close(fd);
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return err;
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}
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if (strcmp(name, module_name) == 0)
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return fd;
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close(fd);
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}
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return -ENOENT;
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}
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void test_module_fentry_shadow(void)
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{
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struct btf *vmlinux_btf = NULL, *mod_btf = NULL;
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int err, i;
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int btf_fd[2] = {};
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int prog_fd[2] = {};
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int link_fd[2] = {};
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__s32 btf_id[2] = {};
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LIBBPF_OPTS(bpf_prog_load_opts, load_opts,
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.expected_attach_type = BPF_TRACE_FENTRY,
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);
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const struct bpf_insn trace_program[] = {
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BPF_MOV64_IMM(BPF_REG_0, 0),
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BPF_EXIT_INSN(),
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};
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vmlinux_btf = btf__load_vmlinux_btf();
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if (!ASSERT_OK_PTR(vmlinux_btf, "load_vmlinux_btf"))
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return;
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btf_fd[1] = get_bpf_testmod_btf_fd();
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if (!ASSERT_GE(btf_fd[1], 0, "get_bpf_testmod_btf_fd"))
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goto out;
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mod_btf = btf_get_from_fd(btf_fd[1], vmlinux_btf);
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if (!ASSERT_OK_PTR(mod_btf, "btf_get_from_fd"))
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goto out;
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btf_id[0] = btf__find_by_name_kind(vmlinux_btf, symbol_name, BTF_KIND_FUNC);
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if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name"))
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goto out;
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btf_id[1] = btf__find_by_name_kind(mod_btf, symbol_name, BTF_KIND_FUNC);
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if (!ASSERT_GT(btf_id[1], 0, "btf_find_by_name"))
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goto out;
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for (i = 0; i < 2; i++) {
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load_opts.attach_btf_id = btf_id[i];
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load_opts.attach_btf_obj_fd = btf_fd[i];
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prog_fd[i] = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL",
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trace_program,
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sizeof(trace_program) / sizeof(struct bpf_insn),
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&load_opts);
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if (!ASSERT_GE(prog_fd[i], 0, "bpf_prog_load"))
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goto out;
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/* If the verifier incorrectly resolves addresses of the
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* shadowed functions and uses the same address for both the
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* vmlinux and the bpf_testmod functions, this will fail on
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* attempting to create two trampolines for the same address,
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* which is forbidden.
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*/
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link_fd[i] = bpf_link_create(prog_fd[i], 0, BPF_TRACE_FENTRY, NULL);
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if (!ASSERT_GE(link_fd[i], 0, "bpf_link_create"))
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goto out;
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}
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err = bpf_prog_test_run_opts(prog_fd[0], NULL);
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ASSERT_OK(err, "running test");
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out:
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btf__free(vmlinux_btf);
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btf__free(mod_btf);
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for (i = 0; i < 2; i++) {
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if (btf_fd[i])
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close(btf_fd[i]);
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if (prog_fd[i] > 0)
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close(prog_fd[i]);
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if (link_fd[i] > 0)
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close(link_fd[i]);
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}
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}
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