Test struct_ops programs returning referenced kptr. When the return type
of a struct_ops operator is pointer to struct, the verifier should
only allow programs that return a scalar NULL or a non-local kptr with the
correct type in its unmodified form.
Signed-off-by: Amery Hung <amery.hung@xxxxxxxxxxxxx>
---
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 8 ++
.../selftests/bpf/bpf_testmod/bpf_testmod.h | 4 +
.../prog_tests/test_struct_ops_kptr_return.c | 87 +++++++++++++++++++
.../bpf/progs/struct_ops_kptr_return.c | 29 +++++++
...uct_ops_kptr_return_fail__invalid_scalar.c | 24 +++++
.../struct_ops_kptr_return_fail__local_kptr.c | 30 +++++++
...uct_ops_kptr_return_fail__nonzero_offset.c | 23 +++++
.../struct_ops_kptr_return_fail__wrong_type.c | 28 ++++++
8 files changed, 233 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c
create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 244234546ae2..cfab09f16cc2 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -1141,11 +1141,19 @@ static int bpf_testmod_ops__test_refcounted(int dummy,
return 0;
}
+static struct task_struct *
+bpf_testmod_ops__test_return_ref_kptr(int dummy, struct task_struct *task__ref,
+ struct cgroup *cgrp)
+{
+ return NULL;
+}
+
static struct bpf_testmod_ops __bpf_testmod_ops = {
.test_1 = bpf_testmod_test_1,
.test_2 = bpf_testmod_test_2,
.test_maybe_null = bpf_testmod_ops__test_maybe_null,
.test_refcounted = bpf_testmod_ops__test_refcounted,
+ .test_return_ref_kptr = bpf_testmod_ops__test_return_ref_kptr,
};
struct bpf_struct_ops bpf_bpf_testmod_ops = {
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index 0e31586c1353..a66659314e67 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -6,6 +6,7 @@
#include <linux/types.h>
struct task_struct;
+struct cgroup;
struct bpf_testmod_test_read_ctx {
char *buf;
@@ -38,6 +39,9 @@ struct bpf_testmod_ops {
int (*unsupported_ops)(void);
/* Used to test ref_acquired arguments. */
int (*test_refcounted)(int dummy, struct task_struct *task);
+ /* Used to test returning referenced kptr. */
+ struct task_struct *(*test_return_ref_kptr)(int dummy, struct task_struct *task,
+ struct cgroup *cgrp);
/* The following fields are used to test shadow copies. */
char onebyte;
diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c
new file mode 100644
index 000000000000..bc2fac39215a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c
@@ -0,0 +1,87 @@
+#include <test_progs.h>
+
+#include "struct_ops_kptr_return.skel.h"
+#include "struct_ops_kptr_return_fail__wrong_type.skel.h"
+#include "struct_ops_kptr_return_fail__invalid_scalar.skel.h"
+#include "struct_ops_kptr_return_fail__nonzero_offset.skel.h"
+#include "struct_ops_kptr_return_fail__local_kptr.skel.h"
+
+/* Test that the verifier accepts a program that acquires a referenced
+ * kptr and releases the reference through return
+ */
+static void kptr_return(void)
+{
+ struct struct_ops_kptr_return *skel;
+
+ skel = struct_ops_kptr_return__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "struct_ops_module_open_and_load"))
+ return;
+
+ struct_ops_kptr_return__destroy(skel);
+}
+
+/* Test that the verifier rejects a program that returns a kptr of the
+ * wrong type
+ */
+static void kptr_return_fail__wrong_type(void)
+{
+ struct struct_ops_kptr_return_fail__wrong_type *skel;
+
+ skel = struct_ops_kptr_return_fail__wrong_type__open_and_load();
+ if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__wrong_type__open_and_load"))
+ return;
+
+ struct_ops_kptr_return_fail__wrong_type__destroy(skel);
+}
+
+/* Test that the verifier rejects a program that returns a non-null scalar */
+static void kptr_return_fail__invalid_scalar(void)
+{
+ struct struct_ops_kptr_return_fail__invalid_scalar *skel;
+
+ skel = struct_ops_kptr_return_fail__invalid_scalar__open_and_load();
+ if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__invalid_scalar__open_and_load"))
+ return;
+
+ struct_ops_kptr_return_fail__invalid_scalar__destroy(skel);
+}
+
+/* Test that the verifier rejects a program that returns kptr with non-zero offset */
+static void kptr_return_fail__nonzero_offset(void)
+{
+ struct struct_ops_kptr_return_fail__nonzero_offset *skel;
+
+ skel = struct_ops_kptr_return_fail__nonzero_offset__open_and_load();
+ if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__nonzero_offset__open_and_load"))
+ return;
+
+ struct_ops_kptr_return_fail__nonzero_offset__destroy(skel);
+}
+
+/* Test that the verifier rejects a program that returns local kptr */
+static void kptr_return_fail__local_kptr(void)
+{
+ struct struct_ops_kptr_return_fail__local_kptr *skel;
+
+ skel = struct_ops_kptr_return_fail__local_kptr__open_and_load();
+ if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__local_kptr__open_and_load"))
+ return;
+
+ struct_ops_kptr_return_fail__local_kptr__destroy(skel);
+}
+
+void test_struct_ops_kptr_return(void)
+{
+ if (test__start_subtest("kptr_return"))
+ kptr_return();
+ if (test__start_subtest("kptr_return_fail__wrong_type"))
+ kptr_return_fail__wrong_type();
+ if (test__start_subtest("kptr_return_fail__invalid_scalar"))
+ kptr_return_fail__invalid_scalar();
+ if (test__start_subtest("kptr_return_fail__nonzero_offset"))
+ kptr_return_fail__nonzero_offset();
+ if (test__start_subtest("kptr_return_fail__local_kptr"))
+ kptr_return_fail__local_kptr();
+}
+
+
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c
new file mode 100644
index 000000000000..29b7719cd4c9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c
@@ -0,0 +1,29 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* This test struct_ops BPF programs returning referenced kptr. The verifier should
+ * allow a referenced kptr or a NULL pointer to be returned. A referenced kptr to task
+ * here is acquried automatically as the task argument is tagged with "__ref".
+ */
+SEC("struct_ops/test_return_ref_kptr")
+struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy,
+ struct task_struct *task, struct cgroup *cgrp)
+{
+ if (dummy % 2) {
+ bpf_task_release(task);
+ return NULL;
+ }
+ return task;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_kptr_return = {
+ .test_return_ref_kptr = (void *)test_return_ref_kptr,
+};
+
+
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c
new file mode 100644
index 000000000000..d67982ba8224
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c
@@ -0,0 +1,24 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* This test struct_ops BPF programs returning referenced kptr. The verifier should
+ * reject programs returning a non-zero scalar value.
+ */
+SEC("struct_ops/test_return_ref_kptr")
+struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy,
+ struct task_struct *task, struct cgroup *cgrp)
+{
+ bpf_task_release(task);
+ return (struct task_struct *)1;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_kptr_return = {
+ .test_return_ref_kptr = (void *)test_return_ref_kptr,
+};
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c
new file mode 100644
index 000000000000..9a4247432539
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c
@@ -0,0 +1,30 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* This test struct_ops BPF programs returning referenced kptr. The verifier should
+ * reject programs returning a local kptr.
+ */
+SEC("struct_ops/test_return_ref_kptr")
+struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy,
+ struct task_struct *task, struct cgroup *cgrp)
+{
+ struct task_struct *t;
+
+ t = bpf_obj_new(typeof(*task));
+ if (!t)
+ return task;
+
+ return t;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_kptr_return = {
+ .test_return_ref_kptr = (void *)test_return_ref_kptr,
+};
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c
new file mode 100644
index 000000000000..5bb0b4029d11
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c
@@ -0,0 +1,23 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* This test struct_ops BPF programs returning referenced kptr. The verifier should
+ * reject programs returning a modified referenced kptr.
+ */
+SEC("struct_ops/test_return_ref_kptr")
+struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy,
+ struct task_struct *task, struct cgroup *cgrp)
+{
+ return (struct task_struct *)&task->jobctl;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_kptr_return = {
+ .test_return_ref_kptr = (void *)test_return_ref_kptr,
+};
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c
new file mode 100644
index 000000000000..32365cb7af49
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c
@@ -0,0 +1,28 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* This test struct_ops BPF programs returning referenced kptr. The verifier should
+ * reject programs returning a referenced kptr of the wrong type.
+ */
+SEC("struct_ops/test_return_ref_kptr")
+struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy,
+ struct task_struct *task, struct cgroup *cgrp)
+{
+ struct task_struct *ret;
+
+ ret = (struct task_struct *)bpf_cgroup_acquire(cgrp);
+ bpf_task_release(task);
+
+ return ret;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_kptr_return = {
+ .test_return_ref_kptr = (void *)test_return_ref_kptr,
+};
--
2.20.1
