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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Red Hat, Inc. */
#include <test_progs.h>
#include "fentry_recursive.skel.h"
#include "fentry_recursive_target.skel.h"
#include <bpf/btf.h>
#include "bpf/libbpf_internal.h"
/* Test recursive attachment of tracing progs with more than one nesting level
* is not possible. Create a chain of attachment, verify that the last prog
* will fail. Depending on the arguments, following cases are tested:
*
* - Recursive loading of tracing progs, without attaching (attach = false,
* detach = false). The chain looks like this:
* load target
* load fentry1 -> target
* load fentry2 -> fentry1 (fail)
*
* - Recursive attach of tracing progs (attach = true, detach = false). The
* chain looks like this:
* load target
* load fentry1 -> target
* attach fentry1 -> target
* load fentry2 -> fentry1 (fail)
*
* - Recursive attach and detach of tracing progs (attach = true, detach =
* true). This validates that attach_tracing_prog flag will be set throughout
* the whole lifecycle of an fentry prog, independently from whether it's
* detached. The chain looks like this:
* load target
* load fentry1 -> target
* attach fentry1 -> target
* detach fentry1
* load fentry2 -> fentry1 (fail)
*/
static void test_recursive_fentry_chain(bool attach, bool detach)
{
struct fentry_recursive_target *target_skel = NULL;
struct fentry_recursive *tracing_chain[2] = {};
struct bpf_program *prog;
int prev_fd, err;
target_skel = fentry_recursive_target__open_and_load();
if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
return;
/* Create an attachment chain with two fentry progs */
for (int i = 0; i < 2; i++) {
tracing_chain[i] = fentry_recursive__open();
if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
goto close_prog;
/* The first prog in the chain is going to be attached to the target
* fentry program, the second one to the previous in the chain.
*/
prog = tracing_chain[i]->progs.recursive_attach;
if (i == 0) {
prev_fd = bpf_program__fd(target_skel->progs.test1);
err = bpf_program__set_attach_target(prog, prev_fd, "test1");
} else {
prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
}
if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
goto close_prog;
err = fentry_recursive__load(tracing_chain[i]);
/* The first attach should succeed, the second fail */
if (i == 0) {
if (!ASSERT_OK(err, "fentry_recursive__load"))
goto close_prog;
if (attach) {
err = fentry_recursive__attach(tracing_chain[i]);
if (!ASSERT_OK(err, "fentry_recursive__attach"))
goto close_prog;
}
if (detach) {
/* Flag attach_tracing_prog should still be set, preventing
* attachment of the following prog.
*/
fentry_recursive__detach(tracing_chain[i]);
}
} else {
if (!ASSERT_ERR(err, "fentry_recursive__load"))
goto close_prog;
}
}
close_prog:
fentry_recursive_target__destroy(target_skel);
for (int i = 0; i < 2; i++) {
fentry_recursive__destroy(tracing_chain[i]);
}
}
void test_recursive_fentry(void)
{
if (test__start_subtest("attach"))
test_recursive_fentry_chain(true, false);
if (test__start_subtest("load"))
test_recursive_fentry_chain(false, false);
if (test__start_subtest("detach"))
test_recursive_fentry_chain(true, true);
}
/* Test that a tracing prog reattachment (when we land in
* "prog->aux->dst_trampoline and tgt_prog is NULL" branch in
* bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf
*/
void test_fentry_attach_btf_presence(void)
{
struct fentry_recursive_target *target_skel = NULL;
struct fentry_recursive *tracing_skel = NULL;
struct bpf_program *prog;
int err, link_fd, tgt_prog_fd;
target_skel = fentry_recursive_target__open_and_load();
if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
goto close_prog;
tracing_skel = fentry_recursive__open();
if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
goto close_prog;
prog = tracing_skel->progs.recursive_attach;
tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target");
if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
goto close_prog;
err = fentry_recursive__load(tracing_skel);
if (!ASSERT_OK(err, "fentry_recursive__load"))
goto close_prog;
tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach);
link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL);
if (!ASSERT_GE(link_fd, 0, "link_fd"))
goto close_prog;
fentry_recursive__detach(tracing_skel);
err = fentry_recursive__attach(tracing_skel);
ASSERT_ERR(err, "fentry_recursive__attach");
close_prog:
fentry_recursive_target__destroy(target_skel);
fentry_recursive__destroy(tracing_skel);
}
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