Add a new exe_file_kfunc test suite that is responsible for verifying
the behaviour of the newly added exe_file based BPF kfuncs.
For now, this new exe_file_kfunc test suite covers the following BPF
kfuncs:
struct file *bpf_get_task_exe_file(struct task_struct *task);
struct file *bpf_get_mm_exe_file(struct mm_struct *mm);
void bpf_put_file(struct file *f);
Signed-off-by: Matt Bobrowski <mattbobrowski@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/exe_file_kfunc.c | 49 +++++
.../bpf/progs/exe_file_kfunc_common.h | 23 +++
.../bpf/progs/exe_file_kfunc_failure.c | 181 ++++++++++++++++++
.../bpf/progs/exe_file_kfunc_success.c | 52 +++++
4 files changed, 305 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/exe_file_kfunc.c
create mode 100644 tools/testing/selftests/bpf/progs/exe_file_kfunc_common.h
create mode 100644 tools/testing/selftests/bpf/progs/exe_file_kfunc_failure.c
create mode 100644 tools/testing/selftests/bpf/progs/exe_file_kfunc_success.c
diff --git a/tools/testing/selftests/bpf/prog_tests/exe_file_kfunc.c b/tools/testing/selftests/bpf/prog_tests/exe_file_kfunc.c
new file mode 100644
index 000000000000..5900c1d4e820
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/exe_file_kfunc.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Google LLC. */
+
+#define _GNU_SOURCE
+#include <test_progs.h>
+
+#include "exe_file_kfunc_failure.skel.h"
+#include "exe_file_kfunc_success.skel.h"
+
+static void run_test(const char *prog_name)
+{
+ struct bpf_link *link;
+ struct bpf_program *prog;
+ struct exe_file_kfunc_success *skel;
+
+ skel = exe_file_kfunc_success__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "file_kfunc_success__open_and_load"))
+ return;
+
+ link = NULL;
+ prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+ if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+ goto cleanup;
+
+ link = bpf_program__attach(prog);
+ ASSERT_OK_PTR(link, "bpf_program__attach");
+cleanup:
+ bpf_link__destroy(link);
+ exe_file_kfunc_success__destroy(skel);
+}
+
+static const char * const success_tests[] = {
+ "get_task_exe_file_and_put_kfunc_from_current",
+ "get_task_exe_file_and_put_kfunc_from_argument",
+ "get_mm_exe_file_and_put_kfunc_from_current",
+};
+
+void test_exe_file_kfunc(void)
+{
+ int i = 0;
+
+ for (; i < ARRAY_SIZE(success_tests); i++) {
+ if (!test__start_subtest(success_tests[i]))
+ continue;
+ run_test(success_tests[i]);
+ }
+
+ RUN_TESTS(exe_file_kfunc_failure);
+}
diff --git a/tools/testing/selftests/bpf/progs/exe_file_kfunc_common.h b/tools/testing/selftests/bpf/progs/exe_file_kfunc_common.h
new file mode 100644
index 000000000000..6623bcc130c3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/exe_file_kfunc_common.h
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Google LLC. */
+
+#ifndef _FILE_KFUNC_COMMON_H
+#define _FILE_KFUNC_COMMON_H
+
+#include <vmlinux.h>
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#include "bpf_misc.h"
+
+struct mm_struct *bpf_task_mm_grab(struct task_struct *task) __ksym;
+void bpf_mm_drop(struct mm_struct *mm) __ksym;
+
+struct file *bpf_get_task_exe_file(struct task_struct *task) __ksym;
+struct file *bpf_get_mm_exe_file(struct mm_struct *mm) __ksym;
+void bpf_put_file(struct file *f) __ksym;
+
+char _license[] SEC("license") = "GPL";
+
+#endif /* _FILE_KFUNC_COMMON_H */
diff --git a/tools/testing/selftests/bpf/progs/exe_file_kfunc_failure.c b/tools/testing/selftests/bpf/progs/exe_file_kfunc_failure.c
new file mode 100644
index 000000000000..8a4464481531
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/exe_file_kfunc_failure.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Google LLC. */
+
+#include "exe_file_kfunc_common.h"
+
+SEC("lsm.s/file_open")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(get_task_exe_file_kfunc_null)
+{
+ struct file *acquired;
+
+ /* Can't pass a NULL pointer to bpf_get_task_exe_file(). */
+ acquired = bpf_get_task_exe_file(NULL);
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("Possibly NULL pointer passed to trusted arg0")
+int BPF_PROG(get_mm_exe_file_kfunc_null)
+{
+ struct file *acquired;
+
+ /* Can't pass a NULL pointer to bpf_get_mm_exe_file(). */
+ acquired = bpf_get_mm_exe_file(NULL);
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/inode_getxattr")
+__failure __msg("arg#0 pointer type STRUCT task_struct must point to scalar, or struct with scalar")
+int BPF_PROG(get_task_exe_file_kfunc_fp)
+{
+ u64 x;
+ struct file *acquired;
+ struct task_struct *fp;
+
+ fp = (struct task_struct *)&x;
+ /* Can't pass random frame pointer to bpf_get_task_exe_file(). */
+ acquired = bpf_get_task_exe_file(fp);
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/inode_getxattr")
+__failure __msg("arg#0 pointer type STRUCT mm_struct must point to scalar, or struct with scalar")
+int BPF_PROG(get_mm_exe_file_kfunc_fp)
+{
+ int x;
+ struct file *acquired;
+ struct mm_struct *fp;
+
+ fp = (struct mm_struct *)&x;
+ /* Can't pass random frame pointer to bpf_get_mm_exe_file(). */
+ acquired = bpf_get_mm_exe_file(fp);
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("R1 must be referenced or trusted")
+int BPF_PROG(get_task_exe_file_kfunc_untrusted)
+{
+ struct file *acquired;
+ struct task_struct *parent;
+
+ /* Walking a trusted struct task_struct returned from
+ * bpf_get_current_task_btf() yields an untrusted pointer. */
+ parent = bpf_get_current_task_btf()->parent;
+ /* Can't pass untrusted pointer to bpf_get_task_exe_file(). */
+ acquired = bpf_get_task_exe_file(parent);
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("R1 must be referenced or trusted")
+int BPF_PROG(get_mm_exe_file_kfunc_untrusted)
+{
+ struct file *acquired;
+ struct mm_struct *mm;
+
+ /* Walking a struct task_struct obtained from bpf_get_current_task_btf()
+ * yields an untrusted pointer. */
+ mm = bpf_get_current_task_btf()->mm;
+ /* Can't pass untrusted pointer to bpf_get_mm_exe_file(). */
+ acquired = bpf_get_mm_exe_file(mm);
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("Unreleased reference")
+int BPF_PROG(get_task_exe_file_kfunc_unreleased)
+{
+ struct file *acquired;
+
+ acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
+ if (!acquired)
+ return 0;
+ __sink(acquired);
+
+ /* Acquired but never released. */
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("Unreleased reference")
+int BPF_PROG(get_mm_exe_file_kfunc_unreleased)
+{
+ struct file *acquired;
+ struct mm_struct *mm;
+
+ mm = bpf_task_mm_grab(bpf_get_current_task_btf());
+ if (!mm)
+ return 0;
+
+ acquired = bpf_get_mm_exe_file(mm);
+ if (!acquired) {
+ bpf_mm_drop(mm);
+ return 0;
+ }
+ __sink(acquired);
+ bpf_mm_drop(mm);
+
+ /* Acquired but never released. */
+ return 0;
+}
+
+SEC("lsm/file_open")
+__failure __msg("program must be sleepable to call sleepable kfunc bpf_put_file")
+int BPF_PROG(put_file_kfunc_not_sleepable, struct file *f)
+{
+ struct file *acquired;
+
+ acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
+ if (!acquired)
+ return 0;
+
+ /* Can't call bpf_put_file() from non-sleepable BPF program. */
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("release kernel function bpf_put_file expects")
+int BPF_PROG(put_file_kfunc_unacquired, struct file *f)
+{
+ /* Can't release an unacquired pointer. */
+ bpf_put_file(f);
+
+ return 0;
+}
+
+SEC("tp_btf/task_newtask")
+__failure __msg("calling kernel function bpf_get_task_exe_file is not allowed")
+int BPF_PROG(get_task_exe_file_kfunc_not_lsm_prog, struct task_struct *task)
+{
+ struct file *acquired;
+
+ /* bpf_get_task_exe_file() can only be called from BPF LSM program. */
+ acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/exe_file_kfunc_success.c b/tools/testing/selftests/bpf/progs/exe_file_kfunc_success.c
new file mode 100644
index 000000000000..ae789cb0a9ae
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/exe_file_kfunc_success.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Google LLC. */
+
+#include "exe_file_kfunc_common.h"
+
+SEC("lsm.s/file_open")
+int BPF_PROG(get_task_exe_file_and_put_kfunc_from_current)
+{
+ struct file *acquired;
+
+ acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/task_alloc")
+int BPF_PROG(get_task_exe_file_and_put_kfunc_from_argument,
+ struct task_struct *task)
+{
+ struct file *acquired;
+
+ acquired = bpf_get_task_exe_file(task);
+ if (!acquired)
+ return 0;
+ bpf_put_file(acquired);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+int BPF_PROG(get_mm_exe_file_and_put_kfunc_from_current)
+{
+ struct file *acquired;
+ struct mm_struct *mm;
+
+ mm = bpf_task_mm_grab(bpf_get_current_task_btf());
+ if (!mm)
+ return 0;
+
+ acquired = bpf_get_mm_exe_file(mm);
+ if (!acquired) {
+ bpf_mm_drop(mm);
+ return 0;
+ }
+ bpf_put_file(acquired);
+ bpf_mm_drop(mm);
+
+ return 0;
+}
--
2.44.0.rc0.258.g7320e95886-goog
/M
