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selftests/bpf: Uprobe tests should verify param/return values

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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: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649245431-29956-4-git-send-email-alan.maguire@oracle.com
This commit is contained in:
Alan Maguire 2022-04-06 12:43:51 +01:00 committed by Andrii Nakryiko
parent 90db26e6be
commit 1717e24801
2 changed files with 50 additions and 18 deletions
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25
tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c
View File

@ -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);
}

43
tools/testing/selftests/bpf/progs/test_uprobe_autoattach.c
View File

@ -1,15 +1,22 @@
// 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;
}