diff mbox series

[bpf-next,v2,3/3] bpf/selftests: Test PTR_TO_RDONLY_MEM

Message ID 20211025231256.4030142-4-haoluo@google.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Prevent writing read-only memory | expand

Checks

Context Check Description
netdev/cover_letter success Series has a cover letter
netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 7 maintainers not CCed: john.fastabend@gmail.com linux-kselftest@vger.kernel.org yhs@fb.com netdev@vger.kernel.org songliubraving@fb.com kafai@fb.com shuah@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success No Fixes tag
netdev/checkpatch warning WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? WARNING: line length of 83 exceeds 80 columns
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success No static functions without inline keyword in header files
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next success VM_Test

Commit Message

Hao Luo Oct. 25, 2021, 11:12 p.m. UTC 
This test verifies that a ksym of non-struct can not be directly
updated.

Signed-off-by: Hao Luo <haoluo@google.com>
---
 Changes since v1:
  - Replaced CHECK() with ASSERT_ERR_PTR()
  - Commented in the test for the reason of verification failure.

 .../selftests/bpf/prog_tests/ksyms_btf.c      | 14 +++++++++
 .../bpf/progs/test_ksyms_btf_write_check.c    | 29 +++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
index cf3acfa5a91d..69455fe90ac3 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c
@@ -7,6 +7,7 @@ 
 #include "test_ksyms_btf.skel.h"
 #include "test_ksyms_btf_null_check.skel.h"
 #include "test_ksyms_weak.skel.h"
+#include "test_ksyms_btf_write_check.skel.h"
 
 static int duration;
 
@@ -109,6 +110,16 @@  static void test_weak_syms(void)
 	test_ksyms_weak__destroy(skel);
 }
 
+static void test_write_check(void)
+{
+	struct test_ksyms_btf_write_check *skel;
+
+	skel = test_ksyms_btf_write_check__open_and_load();
+	ASSERT_ERR_PTR(skel, "unexpected load of a prog writing to ksym memory\n");
+
+	test_ksyms_btf_write_check__destroy(skel);
+}
+
 void test_ksyms_btf(void)
 {
 	int percpu_datasec;
@@ -136,4 +147,7 @@  void test_ksyms_btf(void)
 
 	if (test__start_subtest("weak_ksyms"))
 		test_weak_syms();
+
+	if (test__start_subtest("write_check"))
+		test_write_check();
 }
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
new file mode 100644
index 000000000000..2180c41cd890
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf_write_check.c
@@ -0,0 +1,29 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google */
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+
+extern const int bpf_prog_active __ksym; /* int type global var. */
+
+SEC("raw_tp/sys_enter")
+int handler(const void *ctx)
+{
+	int *active;
+	__u32 cpu;
+
+	cpu = bpf_get_smp_processor_id();
+	active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
+	if (active) {
+		/* Kernel memory obtained from bpf_{per,this}_cpu_ptr
+		 * is read-only, should _not_ pass verification.
+		 */
+		/* WRITE_ONCE */
+		*(volatile int *)active = -1;
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";