[bpf-next,07/11] bpf/selftests: add selftests for exe_file acquire/release BPF kfuncs

Message ID	c626e45e0d6bf37e81c6581f66b9f82fb6a19d1d.1708377880.git.mattbobrowski@google.com (mailing list archive)
State	New, archived
Headers	show Received: from mail-ed1-f45.google.com (mail-ed1-f45.google.com [209.85.208.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F2B55FDC6 for <linux-fsdevel@vger.kernel.org>; Tue, 20 Feb 2024 09:28:15 +0000 (UTC) Date: Tue, 20 Feb 2024 09:28:10 +0000 From: Matt Bobrowski <mattbobrowski@google.com> To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, kpsingh@google.com, jannh@google.com, jolsa@kernel.org, daniel@iogearbox.net, brauner@kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH bpf-next 07/11] bpf/selftests: add selftests for exe_file acquire/release BPF kfuncs Message-ID: <c626e45e0d6bf37e81c6581f66b9f82fb6a19d1d.1708377880.git.mattbobrowski@google.com> References: <cover.1708377880.git.mattbobrowski@google.com> Precedence: bulk MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <cover.1708377880.git.mattbobrowski@google.com>
Series	bpf: probe-read bpf_d_path() and add new acquire/release BPF kfuncs \| expand [bpf-next,00/11] bpf: probe-read bpf_d_path() and add new acquire/release BPF kfuncs [bpf-next,01/11] bpf: make bpf_d_path() helper use probe-read semantics [bpf-next,02/11] bpf/selftests: adjust selftests for BPF helper bpf_d_path() [bpf-next,03/11] bpf: rename fs_kfunc_set_ids to lsm_kfunc_set_ids [bpf-next,04/11] bpf: add new acquire/release BPF kfuncs for mm_struct [bpf-next,05/11] bpf/selftests: add selftests for mm_struct acquire/release BPF kfuncs [bpf-next,06/11] bpf: add new acquire/release based BPF kfuncs for exe_file [bpf-next,07/11] bpf/selftests: add selftests for exe_file acquire/release BPF kfuncs [bpf-next,08/11] bpf: add acquire/release based BPF kfuncs for fs_struct's paths [bpf-next,09/11] bpf/selftests: add selftests for root/pwd path based BPF kfuncs [bpf-next,10/11] bpf: add trusted d_path() based BPF kfunc bpf_path_d_path() [bpf-next,11/11] bpf/selftests: adapt selftests test_d_path for BPF kfunc bpf_path_d_path()

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; +}

[bpf-next,07/11] bpf/selftests: add selftests for exe_file acquire/release BPF kfuncs

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Patch