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Subject[PATCH bpf-next v2 3/3] selftests/bpf: add destructive kfunc test
Date
Add a test checking that programs calling destructive kfuncs can only do
so if they have CAP_SYS_BOOT capabilities.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
net/bpf/test_run.c | 5 +++
.../selftests/bpf/prog_tests/kfunc_call.c | 36 +++++++++++++++++++
.../bpf/progs/kfunc_call_destructive.c | 14 ++++++++
3 files changed, 55 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/kfunc_call_destructive.c

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index cbc9cd5058cb..afa7125252f6 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -695,6 +695,10 @@ noinline void bpf_kfunc_call_test_ref(struct prog_test_ref_kfunc *p)
{
}

+noinline void bpf_kfunc_call_test_destructive(void)
+{
+}
+
__diag_pop();

ALLOW_ERROR_INJECTION(bpf_modify_return_test, ERRNO);
@@ -719,6 +723,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_pass1)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE)
BTF_SET8_END(test_sk_check_kfunc_ids)

static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c
index c00eb974eb85..351fafa006fb 100644
--- a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c
+++ b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c
@@ -5,6 +5,9 @@
#include "kfunc_call_test.lskel.h"
#include "kfunc_call_test_subprog.skel.h"
#include "kfunc_call_test_subprog.lskel.h"
+#include "kfunc_call_destructive.skel.h"
+
+#include "cap_helpers.h"

static void test_main(void)
{
@@ -86,6 +89,36 @@ static void test_subprog_lskel(void)
kfunc_call_test_subprog_lskel__destroy(skel);
}

+static int test_destructive_open_and_load(void)
+{
+ struct kfunc_call_destructive *skel;
+ int err;
+
+ skel = kfunc_call_destructive__open();
+ if (!ASSERT_OK_PTR(skel, "prog_open"))
+ return -1;
+
+ err = kfunc_call_destructive__load(skel);
+
+ kfunc_call_destructive__destroy(skel);
+
+ return err;
+}
+
+static void test_destructive(void)
+{
+ __u64 save_caps = 0;
+
+ ASSERT_OK(test_destructive_open_and_load(), "succesful_load");
+
+ if (!ASSERT_OK(cap_disable_effective(1ULL << CAP_SYS_BOOT, &save_caps), "drop_caps"))
+ return;
+
+ ASSERT_EQ(test_destructive_open_and_load(), -13, "no_caps_failure");
+
+ cap_enable_effective(save_caps, NULL);
+}
+
void test_kfunc_call(void)
{
if (test__start_subtest("main"))
@@ -96,4 +129,7 @@ void test_kfunc_call(void)

if (test__start_subtest("subprog_lskel"))
test_subprog_lskel();
+
+ if (test__start_subtest("destructive"))
+ test_destructive();
}
diff --git a/tools/testing/selftests/bpf/progs/kfunc_call_destructive.c b/tools/testing/selftests/bpf/progs/kfunc_call_destructive.c
new file mode 100644
index 000000000000..767472bc5a97
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/kfunc_call_destructive.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+extern void bpf_kfunc_call_test_destructive(void) __ksym;
+
+SEC("tc")
+int kfunc_destructive_test(void)
+{
+ bpf_kfunc_call_test_destructive();
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.35.3
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