| Message ID | 20250308013314.719150-3-bboscaccy@linux.microsoft.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | security: Propagate caller information in bpf hooks | expand |
On Fri, Mar 7, 2025 at 5:33 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> > --- > .../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 > > 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..479ad5de3737e > --- /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; > + > + ret = test_kernel_flag__attach(lsm_skel); > + if (!ASSERT_OK(ret, "test_kernel_flag__attach")) > + goto close_prog; > + > + lsm_skel->bss->monitored_pid = getpid(); We usually set monitored_pid before attaching the program. > + > + /* 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_pid = 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..9ca01aadb6656 > --- /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_pid; > + > +SEC("lsm.s/bpf") > +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size, bool kernel) > +{ > + __u32 pid; > + > + pid = bpf_get_current_pid_tgid() >> 32; > + if (!kernel || pid != monitored_pid) > + return 0; We are blocking lskel load for the pid. This could make parallel testing (test_progs -j) flaky. We should probably change the logic to filtering on monitored_tiid. Thanks, Song > + else > + return -EINVAL; > +} > -- > 2.48.1 > >
On Mon, Mar 10, 2025 at 10:43 AM Blaise Boscaccy <bboscaccy@linux.microsoft.com> wrote: > > Song Liu <song@kernel.org> writes: > > > On Fri, Mar 7, 2025 at 5:33 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> > >> --- > >> .../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 > >> > >> 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..479ad5de3737e > >> --- /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; > >> + > >> + ret = test_kernel_flag__attach(lsm_skel); > >> + if (!ASSERT_OK(ret, "test_kernel_flag__attach")) > >> + goto close_prog; > >> + > >> + lsm_skel->bss->monitored_pid = getpid(); > > > > We usually set monitored_pid before attaching the program. > > > > Okay, copy that. > > >> + > >> + /* 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_pid = 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..9ca01aadb6656 > >> --- /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_pid; > >> + > >> +SEC("lsm.s/bpf") > >> +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size, bool kernel) > >> +{ > >> + __u32 pid; > >> + > >> + pid = bpf_get_current_pid_tgid() >> 32; > >> + if (!kernel || pid != monitored_pid) > >> + return 0; > > > > We are blocking lskel load for the pid. This could make > > parallel testing (test_progs -j) flaky. We should probably > > change the logic to filtering on monitored_tiid. > > > > Curious on this for my own edification. The > > pid = bpf_get_current_pid_tgid() >> 32; > > is used extensively in the current test suite in a bunch of other > tests. Why does that not cause an issue with the other tests during > parallel testing? We are blindly blocking all security_bpf() with kernel=true here, so any lskel load in parallel with this test may fail. On the other hand, existing tests only block some operations under certain conditions. For example, test_cgroup1_hierarchy.c only blocks operations for target_ancestor_cgid. Does this make sense? Thanks, Song
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..479ad5de3737e --- /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; + + ret = test_kernel_flag__attach(lsm_skel); + if (!ASSERT_OK(ret, "test_kernel_flag__attach")) + goto close_prog; + + lsm_skel->bss->monitored_pid = getpid(); + + /* 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_pid = 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..9ca01aadb6656 --- /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_pid; + +SEC("lsm.s/bpf") +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size, bool kernel) +{ + __u32 pid; + + pid = bpf_get_current_pid_tgid() >> 32; + if (!kernel || pid != monitored_pid) + 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