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authorMartin KaFai Lau <kafai@fb.com>2020-10-19 22:42:25 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-10-20 01:57:42 +0300
commit8568c3cefd5143fa0dc09f90e1bc9dc8905292f4 (patch)
tree90ff2079a7ea6260ffe6399e1d00f457cabea8cf /tools
parente710bcc6d92c47bb7d8e803b41ef529c09ad6a9e (diff)
downloadlinux-8568c3cefd5143fa0dc09f90e1bc9dc8905292f4.tar.xz
bpf: selftest: Ensure the return value of the bpf_per_cpu_ptr() must be checked
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
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/prog_tests/ksyms_btf.c57
-rw-r--r--tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c31
2 files changed, 70 insertions, 18 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index 28e26bd3e0ca..b58b775d19f3 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -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();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c
new file mode 100644
index 000000000000..8bc8f7c637bc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_null_check.c
@@ -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";