[PATCH v5 bpf-next 11/12] selftests/bpf: Add uptr failure verifier tests

[Martin KaFai Lau <martin.lau@linux.dev>]

From: Martin KaFai Lau <martin.lau@kernel.org>

Add verifier tests to ensure invalid uptr usages are rejected.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
 .../bpf/prog_tests/task_local_storage.c       |   2 +
 .../selftests/bpf/progs/uptr_failure.c        | 121 ++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/uptr_failure.c

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
index 4abe1621c5c0..55e36956bf52 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
@@ -18,6 +18,7 @@
 #include "uptr_test_common.h"
 #include "task_ls_uptr.skel.h"
 #include "uptr_update_failure.skel.h"
+#include "uptr_failure.skel.h"
 
 static void test_sys_enter_exit(void)
 {
@@ -463,4 +464,5 @@ void test_task_local_storage(void)
 		test_uptr_across_pages();
 	if (test__start_subtest("uptr_update_failure"))
 		test_uptr_update_failure();
+	RUN_TESTS(uptr_failure);
 }
diff --git a/tools/testing/selftests/bpf/progs/uptr_failure.c b/tools/testing/selftests/bpf/progs/uptr_failure.c
new file mode 100644
index 000000000000..e035130c2959
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uptr_failure.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_experimental.h"
+#include "bpf_misc.h"
+#include "uptr_test_common.h"
+
+void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct value_type);
+} datamap SEC(".maps");
+
+/* Avoid fwd user_data type in btf */
+struct user_data __dummy;
+
+SEC("?syscall")
+__failure __msg("store to uptr disallowed")
+int uptr_write(const void *ctx)
+{
+	struct task_struct *task;
+	struct value_type *v;
+
+	task = bpf_get_current_task_btf();
+	v = bpf_task_storage_get(&datamap, task, 0,
+				 BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!v)
+		return 0;
+
+	v->udata = NULL;
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("store to uptr disallowed")
+int uptr_write_nested(const void *ctx)
+{
+	struct task_struct *task;
+	struct value_type *v;
+
+	task = bpf_get_current_task_btf();
+	v = bpf_task_storage_get(&datamap, task, 0,
+				 BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!v)
+		return 0;
+
+	v->nested.udata = NULL;
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("R1 invalid mem access 'mem_or_null'")
+int uptr_no_null_check(const void *ctx)
+{
+	struct task_struct *task;
+	struct value_type *v;
+
+	task = bpf_get_current_task_btf();
+	v = bpf_task_storage_get(&datamap, task, 0,
+				 BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!v)
+		return 0;
+
+	v->udata->result = 0;
+
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("doesn't point to kptr")
+int uptr_kptr_xchg(const void *ctx)
+{
+	struct task_struct *task;
+	struct value_type *v;
+
+	task = bpf_get_current_task_btf();
+	v = bpf_task_storage_get(&datamap, task, 0,
+				 BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!v)
+		return 0;
+
+	bpf_kptr_xchg(&v->udata, NULL);
+
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("invalid mem access 'scalar'")
+int uptr_obj_new(const void *ctx)
+{
+	struct value_type *v;
+	struct cgroup *cgrp;
+
+	v = bpf_obj_new(typeof(*v));
+	if (!v)
+		return 0;
+
+	cgrp = bpf_kptr_xchg(&v->cgrp, NULL);
+	if (cgrp) {
+		/* Avoid fwd cgroup type in btf */
+		int lvl = cgrp->level;
+
+		bpf_cgroup_release(cgrp);
+		bpf_obj_drop(v);
+		return lvl;
+	}
+
+	if (v->udata)
+		v->udata->result = 0;
+
+	bpf_obj_drop(v);
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.43.5