iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: selftest: Ensure the return value of the bpf_per_cpu_ptr() must be checked

Browse Source 
This patch tests all pointers returned by bpf_per_cpu_ptr() must be
tested for NULL first before it can be accessed.

This patch adds a subtest "null_check", so it moves the ".data..percpu"
existence check to the very beginning and before doing any subtest.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201019194225.1051596-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2020-10-19 12:42:25 -07:00 committed by Alexei Starovoitov
parent e710bcc6d9
commit 8568c3cefd
2 changed files with 70 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
View File

@ -5,18 +5,17 @@
#include <bpf/libbpf.h>
#include <bpf/btf.h>
#include "test_ksyms_btf.skel.h"
#include "test_ksyms_btf_null_check.skel.h"
static int duration;
void test_ksyms_btf(void)
static void test_basic(void)
{
__u64 runqueues_addr, bpf_prog_active_addr;
__u32 this_rq_cpu;
int this_bpf_prog_active;
struct test_ksyms_btf *skel = NULL;
struct test_ksyms_btf__data *data;
struct btf *btf;
int percpu_datasec;
int err;
err = kallsyms_find("runqueues", &runqueues_addr);
@ -31,20 +30,6 @@ void test_ksyms_btf(void)
if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_prog_active' not found\n"))
return;
btf = libbpf_find_kernel_btf();
if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n",
PTR_ERR(btf)))
return;
percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu",
BTF_KIND_DATASEC);
if (percpu_datasec < 0) {
printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n",
__func__);
test__skip();
goto cleanup;
}
skel = test_ksyms_btf__open_and_load();
if (CHECK(!skel, "skel_open", "failed to open and load skeleton\n"))
goto cleanup;
@ -83,6 +68,42 @@ void test_ksyms_btf(void)
data->out__bpf_prog_active);
cleanup:
btf__free(btf);
test_ksyms_btf__destroy(skel);
}
static void test_null_check(void)
{
struct test_ksyms_btf_null_check *skel;
skel = test_ksyms_btf_null_check__open_and_load();
CHECK(skel, "skel_open", "unexpected load of a prog missing null check\n");
test_ksyms_btf_null_check__destroy(skel);
}
void test_ksyms_btf(void)
{
int percpu_datasec;
struct btf *btf;
btf = libbpf_find_kernel_btf();
if (CHECK(IS_ERR(btf), "btf_exists", "failed to load kernel BTF: %ld\n",
PTR_ERR(btf)))
return;
percpu_datasec = btf__find_by_name_kind(btf, ".data..percpu",
BTF_KIND_DATASEC);
btf__free(btf);
if (percpu_datasec < 0) {
printf("%s:SKIP:no PERCPU DATASEC in kernel btf\n",
__func__);
test__skip();
return;
}
if (test__start_subtest("basic"))
test_basic();
if (test__start_subtest("null_check"))
test_null_check();
}

31
tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c Normal file
View File

@ -0,0 +1,31 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
extern const struct rq runqueues __ksym; /* struct type global var. */
extern const int bpf_prog_active __ksym; /* int type global var. */
SEC("raw_tp/sys_enter")
int handler(const void *ctx)
{
struct rq *rq;
int *active;
__u32 cpu;
cpu = bpf_get_smp_processor_id();
rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu);
active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
if (active) {
/* READ_ONCE */
*(volatile int *)active;
/* !rq has not been tested, so verifier should reject. */
*(volatile int *)(&rq->cpu);
}
return 0;
}
char _license[] SEC("license") = "GPL";