| Message ID | 20250310221737.821889-3-bboscaccy@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | security: Propagate caller information in bpf hooks | expand |
On Mon, Mar 10, 2025 at 3:18 PM Blaise Boscaccy <bboscaccy@linux.microsoft.com> wrote: > > This test exercises the kernel flag added to security_bpf by > effectively blocking light-skeletons from loading while allowing > normal skeletons to function as-is. Since this should work with any > arbitrary BPF program, an existing program from LSKELS_EXTRA was > used as a test payload. > > Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com> [...] > + > + /* Test with skel. This should pass the gatekeeper */ > + skel = kfunc_call_test__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel")) > + goto close_prog; > + > + /* Test with lskel. This should fail due to blocking kernel-based bpf() invocations */ > + lskel = kfunc_call_test_lskel__open_and_load(); > + if (!ASSERT_ERR_PTR(lskel, "lskel")) > + goto close_prog; This goto is not necessary. But I don't think we need v8 just for this. Acked-by: Song Liu <song@kernel.org> > + > +close_prog: > + if (skel) > + kfunc_call_test__destroy(skel); > + if (lskel) > + kfunc_call_test_lskel__destroy(lskel); [...]
On Tue, Mar 11, 2025 at 12:07 AM Song Liu <song@kernel.org> wrote: > > + lskel = kfunc_call_test_lskel__open_and_load(); > > + if (!ASSERT_ERR_PTR(lskel, "lskel")) > > + goto close_prog; > > This goto is not necessary. But I don't think we need v8 just for this. I left goto as-is while applying. I felt all error handling being consistent this way is cleaner.
diff --git a/tools/testing/selftests/bpf/prog_tests/kernel_flag.c b/tools/testing/selftests/bpf/prog_tests/kernel_flag.c new file mode 100644 index 0000000000000..a133354ac9bc2 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/kernel_flag.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Microsoft */ +#include <test_progs.h> +#include "kfunc_call_test.skel.h" +#include "kfunc_call_test.lskel.h" +#include "test_kernel_flag.skel.h" + +void test_kernel_flag(void) +{ + struct test_kernel_flag *lsm_skel; + struct kfunc_call_test *skel = NULL; + struct kfunc_call_test_lskel *lskel = NULL; + int ret; + + lsm_skel = test_kernel_flag__open_and_load(); + if (!ASSERT_OK_PTR(lsm_skel, "lsm_skel")) + return; + + lsm_skel->bss->monitored_tid = gettid(); + + ret = test_kernel_flag__attach(lsm_skel); + if (!ASSERT_OK(ret, "test_kernel_flag__attach")) + goto close_prog; + + /* Test with skel. This should pass the gatekeeper */ + skel = kfunc_call_test__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel")) + goto close_prog; + + /* Test with lskel. This should fail due to blocking kernel-based bpf() invocations */ + lskel = kfunc_call_test_lskel__open_and_load(); + if (!ASSERT_ERR_PTR(lskel, "lskel")) + goto close_prog; + +close_prog: + if (skel) + kfunc_call_test__destroy(skel); + if (lskel) + kfunc_call_test_lskel__destroy(lskel); + + lsm_skel->bss->monitored_tid = 0; + test_kernel_flag__destroy(lsm_skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_kernel_flag.c b/tools/testing/selftests/bpf/progs/test_kernel_flag.c new file mode 100644 index 0000000000000..b45fab3be3528 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_kernel_flag.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2025 Microsoft Corporation + * + * Author: Blaise Boscaccy <bboscaccy@linux.microsoft.com> + */ + +#include "vmlinux.h" +#include <errno.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +char _license[] SEC("license") = "GPL"; + +__u32 monitored_tid; + +SEC("lsm.s/bpf") +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size, bool kernel) +{ + __u32 tid; + + tid = bpf_get_current_pid_tgid() & 0xFFFFFFFF; + if (!kernel || tid != monitored_tid) + return 0; + else + return -EINVAL; +}
This test exercises the kernel flag added to security_bpf by effectively blocking light-skeletons from loading while allowing normal skeletons to function as-is. Since this should work with any arbitrary BPF program, an existing program from LSKELS_EXTRA was used as a test payload. Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com> --- .../selftests/bpf/prog_tests/kernel_flag.c | 43 +++++++++++++++++++ .../selftests/bpf/progs/test_kernel_flag.c | 28 ++++++++++++ 2 files changed, 71 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/kernel_flag.c create mode 100644 tools/testing/selftests/bpf/progs/test_kernel_flag.c