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Hallyn" , Mauro Carvalho Chehab , "David S. Miller" , Greg Kroah-Hartman , Nicolas Ferre , Stanislav Fomichev , Quentin Monnet , Andrey Ignatov , Joe Stringer Subject: [PATCH bpf-next v3 09/10] bpf: lsm: Add selftests for BPF_PROG_TYPE_LSM Date: Thu, 23 Jan 2020 07:24:39 -0800 Message-Id: <20200123152440.28956-10-kpsingh@chromium.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200123152440.28956-1-kpsingh@chromium.org> References: <20200123152440.28956-1-kpsingh@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: KP Singh * Load a BPF program that audits mprotect calls * Attach the program to the "file_mprotect" LSM hook. * Do an mprotect on some memory allocated on the heap * Verify if the audit event was received using the shared global result variable. Signed-off-by: KP Singh Reviewed-by: Brendan Jackman Reviewed-by: Florent Revest Reviewed-by: Thomas Garnier --- MAINTAINERS | 3 + tools/testing/selftests/bpf/lsm_helpers.h | 19 ++++++ .../bpf/prog_tests/lsm_mprotect_audit.c | 58 +++++++++++++++++++ .../selftests/bpf/progs/lsm_mprotect_audit.c | 47 +++++++++++++++ 4 files changed, 127 insertions(+) create mode 100644 tools/testing/selftests/bpf/lsm_helpers.h create mode 100644 tools/testing/selftests/bpf/prog_tests/lsm_mprotect_audit.c create mode 100644 tools/testing/selftests/bpf/progs/lsm_mprotect_audit.c diff --git a/MAINTAINERS b/MAINTAINERS index c606b3d89992..32236d89d00b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3210,6 +3210,9 @@ L: bpf@vger.kernel.org S: Maintained F: security/bpf/ F: include/linux/bpf_lsm.h +F: tools/testing/selftests/bpf/lsm_helpers.h +F: tools/testing/selftests/bpf/progs/lsm_mprotect_audit.c +F: tools/testing/selftests/bpf/prog_tests/lsm_mprotect_audit.c BROADCOM B44 10/100 ETHERNET DRIVER M: Michael Chan diff --git a/tools/testing/selftests/bpf/lsm_helpers.h b/tools/testing/selftests/bpf/lsm_helpers.h new file mode 100644 index 000000000000..8bad08f77654 --- /dev/null +++ b/tools/testing/selftests/bpf/lsm_helpers.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright 2019 Google LLC. + */ +#ifndef _LSM_HELPERS_H +#define _LSM_HELPERS_H + +struct lsm_mprotect_audit_result { + /* This ensures that the LSM Hook only monitors the PID requested + * by the loader + */ + __u32 monitored_pid; + /* The number of mprotect calls for the monitored PID. + */ + __u32 mprotect_count; +}; + +#endif /* _LSM_HELPERS_H */ diff --git a/tools/testing/selftests/bpf/prog_tests/lsm_mprotect_audit.c b/tools/testing/selftests/bpf/prog_tests/lsm_mprotect_audit.c new file mode 100644 index 000000000000..ff90b874eafc --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/lsm_mprotect_audit.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright 2019 Google LLC. + */ + +#include +#include +#include +#include +#include "lsm_helpers.h" +#include "lsm_mprotect_audit.skel.h" + +int heap_mprotect(void) +{ + void *buf; + long sz; + + sz = sysconf(_SC_PAGESIZE); + if (sz < 0) + return sz; + + buf = memalign(sz, 2 * sz); + if (buf == NULL) + return -ENOMEM; + + return mprotect(buf, sz, PROT_READ | PROT_EXEC); +} + +void test_lsm_mprotect_audit(void) +{ + struct lsm_mprotect_audit_result *result; + struct lsm_mprotect_audit *skel = NULL; + int err, duration = 0; + + skel = lsm_mprotect_audit__open_and_load(); + if (CHECK(!skel, "skel_load", "lsm_mprotect_audit skeleton failed\n")) + goto close_prog; + + err = lsm_mprotect_audit__attach(skel); + if (CHECK(err, "attach", "lsm_mprotect_audit attach failed: %d\n", err)) + goto close_prog; + + result = &skel->bss->result; + result->monitored_pid = getpid(); + + err = heap_mprotect(); + if (CHECK(err < 0, "heap_mprotect", "err %d errno %d\n", err, errno)) + goto close_prog; + + /* Make sure mprotect_audit program was triggered + * and detected an mprotect on the heap. + */ + CHECK_FAIL(result->mprotect_count != 1); + +close_prog: + lsm_mprotect_audit__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/lsm_mprotect_audit.c b/tools/testing/selftests/bpf/progs/lsm_mprotect_audit.c new file mode 100644 index 000000000000..231cd64fd0f7 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/lsm_mprotect_audit.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright 2019 Google LLC. + */ + +#include +#include +#include "bpf_trace_helpers.h" +#include "lsm_helpers.h" + +char _license[] SEC("license") = "GPL"; + +struct lsm_mprotect_audit_result result = { + .mprotect_count = 0, + .monitored_pid = 0, +}; + +/* + * Define some of the structs used in the BPF program. + * Only the field names and their sizes need to be the + * same as the kernel type, the order is irrelevant. + */ +struct mm_struct { + unsigned long start_brk, brk; +} __attribute__((preserve_access_index)); + +struct vm_area_struct { + unsigned long vm_start, vm_end; + struct mm_struct *vm_mm; +} __attribute__((preserve_access_index)); + +SEC("lsm/file_mprotect") +int BPF_PROG(mprotect_audit, struct vm_area_struct *vma, + unsigned long reqprot, unsigned long prot) +{ + __u32 pid = bpf_get_current_pid_tgid(); + int is_heap = 0; + + is_heap = (vma->vm_start >= vma->vm_mm->start_brk && + vma->vm_end <= vma->vm_mm->brk); + + if (is_heap && result.monitored_pid == pid) + result.mprotect_count++; + + return 0; +} -- 2.20.1