Commit 1717e248 authored by Alan Maguire's avatar Alan Maguire Committed by Andrii Nakryiko
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selftests/bpf: Uprobe tests should verify param/return values 



uprobe/uretprobe tests don't do any validation of arguments/return values,
and without this we can't be sure we are attached to the right function,
or that we are indeed attached to a uprobe or uretprobe.  To fix this
record argument and return value for auto-attached functions and ensure
these match expectations.  Also need to filter by pid to ensure we do
not pick up stray malloc()s since auto-attach traces libc system-wide.

Suggested-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlan Maguire <alan.maguire@oracle.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649245431-29956-4-git-send-email-alan.maguire@oracle.com
parent 90db26e6

tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c

+18 −7
Original line number Diff line number Diff line
@@ -5,14 +5,17 @@ 
#include "test_uprobe_autoattach.skel.h"



/* uprobe attach point */

static void autoattach_trigger_func(void)

static noinline int autoattach_trigger_func(int arg)

{

	asm volatile ("");

	return arg + 1;

}



void test_uprobe_autoattach(void)

{

	struct test_uprobe_autoattach *skel;

	int trigger_val = 100, trigger_ret;

	size_t malloc_sz = 1;

	char *mem;



	skel = test_uprobe_autoattach__open_and_load();
@@ -22,17 +25,25 @@ void test_uprobe_autoattach(void) 
	if (!ASSERT_OK(test_uprobe_autoattach__attach(skel), "skel_attach"))

		goto cleanup;



	skel->bss->test_pid = getpid();



	/* trigger & validate uprobe & uretprobe */

	autoattach_trigger_func();

	trigger_ret = autoattach_trigger_func(trigger_val);



	skel->bss->test_pid = getpid();



	/* trigger & validate shared library u[ret]probes attached by name */

	mem = malloc(1);

	mem = malloc(malloc_sz);

	free(mem);



	ASSERT_EQ(skel->bss->uprobe_byname_res, 1, "check_uprobe_byname_res");

	ASSERT_EQ(skel->bss->uretprobe_byname_res, 2, "check_uretprobe_byname_res");

	ASSERT_EQ(skel->bss->uprobe_byname2_res, 3, "check_uprobe_byname2_res");

	ASSERT_EQ(skel->bss->uretprobe_byname2_res, 4, "check_uretprobe_byname2_res");

	ASSERT_EQ(skel->bss->uprobe_byname_parm1, trigger_val, "check_uprobe_byname_parm1");

	ASSERT_EQ(skel->bss->uprobe_byname_ran, 1, "check_uprobe_byname_ran");

	ASSERT_EQ(skel->bss->uretprobe_byname_rc, trigger_ret, "check_uretprobe_byname_rc");

	ASSERT_EQ(skel->bss->uretprobe_byname_ran, 2, "check_uretprobe_byname_ran");

	ASSERT_EQ(skel->bss->uprobe_byname2_parm1, malloc_sz, "check_uprobe_byname2_parm1");

	ASSERT_EQ(skel->bss->uprobe_byname2_ran, 3, "check_uprobe_byname2_ran");

	ASSERT_EQ(skel->bss->uretprobe_byname2_rc, mem, "check_uretprobe_byname2_rc");

	ASSERT_EQ(skel->bss->uretprobe_byname2_ran, 4, "check_uretprobe_byname2_ran");

cleanup:

	test_uprobe_autoattach__destroy(skel);

}

tools/testing/selftests/bpf/progs/test_uprobe_autoattach.c

+32 −11
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022, Oracle and/or its affiliates. */



#include <linux/ptrace.h>

#include <linux/bpf.h>

#include "vmlinux.h"



#include <bpf/bpf_core_read.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



int uprobe_byname_res = 0;

int uretprobe_byname_res = 0;

int uprobe_byname2_res = 0;

int uretprobe_byname2_res = 0;

int uprobe_byname_parm1 = 0;

int uprobe_byname_ran = 0;

int uretprobe_byname_rc = 0;

int uretprobe_byname_ran = 0;

size_t uprobe_byname2_parm1 = 0;

int uprobe_byname2_ran = 0;

char *uretprobe_byname2_rc = NULL;

int uretprobe_byname2_ran = 0;



int test_pid;



/* This program cannot auto-attach, but that should not stop other

 * programs from attaching.
@@ -23,14 +30,16 @@ int handle_uprobe_noautoattach(struct pt_regs *ctx) 
SEC("uprobe//proc/self/exe:autoattach_trigger_func")

int handle_uprobe_byname(struct pt_regs *ctx)

{

	uprobe_byname_res = 1;

	uprobe_byname_parm1 = PT_REGS_PARM1_CORE(ctx);

	uprobe_byname_ran = 1;

	return 0;

}



SEC("uretprobe//proc/self/exe:autoattach_trigger_func")

int handle_uretprobe_byname(struct pt_regs *ctx)

{

	uretprobe_byname_res = 2;

	uretprobe_byname_rc = PT_REGS_RC_CORE(ctx);

	uretprobe_byname_ran = 2;

	return 0;

}
@@ -38,14 +47,26 @@ int handle_uretprobe_byname(struct pt_regs *ctx) 
SEC("uprobe/libc.so.6:malloc")

int handle_uprobe_byname2(struct pt_regs *ctx)

{

	uprobe_byname2_res = 3;

	int pid = bpf_get_current_pid_tgid() >> 32;



	/* ignore irrelevant invocations */

	if (test_pid != pid)

		return 0;

	uprobe_byname2_parm1 = PT_REGS_PARM1_CORE(ctx);

	uprobe_byname2_ran = 3;

	return 0;

}



SEC("uretprobe/libc.so.6:free")

SEC("uretprobe/libc.so.6:malloc")

int handle_uretprobe_byname2(struct pt_regs *ctx)

{

	uretprobe_byname2_res = 4;

	int pid = bpf_get_current_pid_tgid() >> 32;



	/* ignore irrelevant invocations */

	if (test_pid != pid)

		return 0;

	uretprobe_byname2_rc = (char *)PT_REGS_RC_CORE(ctx);

	uretprobe_byname2_ran = 4;

	return 0;

}