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Message-ID:
<AM6PR03MB58481542FD4940701FE3161F99802@AM6PR03MB5848.eurprd03.prod.outlook.com>
Date: Thu, 15 Aug 2024 17:16:56 +0100
From: Juntong Deng <juntong.deng@...look.com>
To: ast@...nel.org,
daniel@...earbox.net,
john.fastabend@...il.com,
andrii@...nel.org,
martin.lau@...ux.dev,
eddyz87@...il.com,
song@...nel.org,
yonghong.song@...ux.dev,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
jolsa@...nel.org
Cc: bpf@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next 2/2] selftests/bpf: Add tests for iter next method returning valid pointer
This patch adds two test cases for iter next method returning valid
pointer, which can also used as usage examples.
Currently iter next method should return valid pointer.
iter_next_trusted is the correct usage and test if iter next method
return valid pointer. bpf_iter_task_vma_next has KF_RET_NULL flag,
so the returned pointer may be NULL. We need to check if the pointer
is NULL before using it.
iter_next_trusted_or_null is the incorrect usage. There is no checking
before using the pointer, so it will be rejected by the verifier.
Signed-off-by: Juntong Deng <juntong.deng@...look.com>
---
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 5 ++
.../bpf/bpf_testmod/bpf_testmod_kfunc.h | 2 +
.../testing/selftests/bpf/prog_tests/iters.c | 5 +-
.../selftests/bpf/progs/iters_testmod.c | 48 +++++++++++++++++++
4 files changed, 59 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/progs/iters_testmod.c
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index a80b0d2c6f38..810d8005211e 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -176,6 +176,10 @@ __bpf_kfunc void bpf_kfunc_dynptr_test(struct bpf_dynptr *ptr,
{
}
+__bpf_kfunc void bpf_kfunc_valid_pointer_test(struct vm_area_struct *ptr)
+{
+}
+
__bpf_kfunc struct bpf_testmod_ctx *
bpf_testmod_ctx_create(int *err)
{
@@ -533,6 +537,7 @@ BTF_ID_FLAGS(func, bpf_iter_testmod_seq_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_testmod_seq_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_kfunc_common_test)
BTF_ID_FLAGS(func, bpf_kfunc_dynptr_test)
+BTF_ID_FLAGS(func, bpf_kfunc_valid_pointer_test, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_testmod_ctx_create, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_testmod_ctx_release, KF_RELEASE)
BTF_KFUNCS_END(bpf_testmod_common_kfunc_ids)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
index e587a79f2239..8f122dc8a328 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
@@ -144,4 +144,6 @@ void bpf_kfunc_dynptr_test(struct bpf_dynptr *ptr, struct bpf_dynptr *ptr__nulla
struct bpf_testmod_ctx *bpf_testmod_ctx_create(int *err) __ksym;
void bpf_testmod_ctx_release(struct bpf_testmod_ctx *ctx) __ksym;
+void bpf_kfunc_valid_pointer_test(struct vm_area_struct *ptr) __ksym;
+
#endif /* _BPF_TESTMOD_KFUNC_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index 3c440370c1f0..89ff23c4a8bc 100644
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -14,6 +14,7 @@
#include "iters_state_safety.skel.h"
#include "iters_looping.skel.h"
#include "iters_num.skel.h"
+#include "iters_testmod.skel.h"
#include "iters_testmod_seq.skel.h"
#include "iters_task_vma.skel.h"
#include "iters_task.skel.h"
@@ -297,8 +298,10 @@ void test_iters(void)
RUN_TESTS(iters);
RUN_TESTS(iters_css_task);
- if (env.has_testmod)
+ if (env.has_testmod) {
+ RUN_TESTS(iters_testmod);
RUN_TESTS(iters_testmod_seq);
+ }
if (test__start_subtest("num"))
subtest_num_iters();
diff --git a/tools/testing/selftests/bpf/progs/iters_testmod.c b/tools/testing/selftests/bpf/progs/iters_testmod.c
new file mode 100644
index 000000000000..009b9f7ad45c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_testmod.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include "bpf_experimental.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "../bpf_testmod/bpf_testmod_kfunc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("raw_tp/sys_enter")
+__success
+int iter_next_trusted(const void *ctx)
+{
+ struct task_struct *task = bpf_get_current_task_btf();
+ struct bpf_iter_task_vma vma_it;
+ struct vm_area_struct *vma;
+
+ bpf_iter_task_vma_new(&vma_it, task, 0);
+
+ vma = bpf_iter_task_vma_next(&vma_it);
+
+ if (vma == NULL)
+ goto out;
+
+ bpf_kfunc_valid_pointer_test(vma);
+out:
+ bpf_iter_task_vma_destroy(&vma_it);
+ return 0;
+}
+
+SEC("raw_tp/sys_enter")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int iter_next_trusted_or_null(const void *ctx)
+{
+ struct task_struct *task = bpf_get_current_task_btf();
+ struct bpf_iter_task_vma vma_it;
+ struct vm_area_struct *vma;
+
+ bpf_iter_task_vma_new(&vma_it, task, 0);
+
+ vma = bpf_iter_task_vma_next(&vma_it);
+
+ bpf_kfunc_valid_pointer_test(vma);
+
+ bpf_iter_task_vma_destroy(&vma_it);
+ return 0;
+}
--
2.39.2
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