diff mbox series

[bpf-next,v2] bpf/selftests: Test bpf_d_path on rdonly_mem.

Message ID 20220106205525.2116218-1-haoluo@google.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series [bpf-next,v2] bpf/selftests: Test bpf_d_path on rdonly_mem. | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 4 maintainers not CCed: linux-kselftest@vger.kernel.org netdev@vger.kernel.org john.fastabend@gmail.com shuah@kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next success VM_Test
bpf/vmtest-bpf-next-PR success PR summary

Commit Message

Hao Luo Jan. 6, 2022, 8:55 p.m. UTC 
The second parameter of bpf_d_path() can only accept writable
memories. Rdonly_mem obtained from bpf_per_cpu_ptr() can not
be passed into bpf_d_path for modification. This patch adds
a selftest to verify this behavior.

Signed-off-by: Hao Luo <haoluo@google.com>
---
Changelog since v1:
 - remove duplicated vmlinux.h (Yonghong)
 - use 'void *' as type of 'active' (Andrii)
 - use codename instead of descriptive sentense in ASSERT_ERR_PTR's
   error message. (Andrii)

 .../testing/selftests/bpf/prog_tests/d_path.c | 22 ++++++++++++++-
 .../bpf/progs/test_d_path_check_rdonly_mem.c  | 28 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c

Comments

Yonghong Song Jan. 6, 2022, 11:17 p.m. UTC | #1 
On 1/6/22 12:55 PM, Hao Luo wrote:
> The second parameter of bpf_d_path() can only accept writable
> memories. Rdonly_mem obtained from bpf_per_cpu_ptr() can not
> be passed into bpf_d_path for modification. This patch adds
> a selftest to verify this behavior.
> 
> Signed-off-by: Hao Luo <haoluo@google.com>

Acked-by: Yonghong Song <yhs@fb.com>
Andrii Nakryiko Jan. 6, 2022, 11:25 p.m. UTC | #2 
On Thu, Jan 6, 2022 at 3:17 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 1/6/22 12:55 PM, Hao Luo wrote:
> > The second parameter of bpf_d_path() can only accept writable
> > memories. Rdonly_mem obtained from bpf_per_cpu_ptr() can not
> > be passed into bpf_d_path for modification. This patch adds
> > a selftest to verify this behavior.
> >
> > Signed-off-by: Hao Luo <haoluo@google.com>
>
> Acked-by: Yonghong Song <yhs@fb.com>

Applied to bpf-next, thanks.
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/d_path.c b/tools/testing/selftests/bpf/prog_tests/d_path.c
index 0a577a248d34..42bf4272bb5e 100644
--- a/tools/testing/selftests/bpf/prog_tests/d_path.c
+++ b/tools/testing/selftests/bpf/prog_tests/d_path.c
@@ -9,6 +9,7 @@ 
 #define MAX_FILES		7
 
 #include "test_d_path.skel.h"
+#include "test_d_path_check_rdonly_mem.skel.h"
 
 static int duration;
 
@@ -99,7 +100,7 @@  static int trigger_fstat_events(pid_t pid)
 	return ret;
 }
 
-void test_d_path(void)
+static void test_d_path_basic(void)
 {
 	struct test_d_path__bss *bss;
 	struct test_d_path *skel;
@@ -155,3 +156,22 @@  void test_d_path(void)
 cleanup:
 	test_d_path__destroy(skel);
 }
+
+static void test_d_path_check_rdonly_mem(void)
+{
+	struct test_d_path_check_rdonly_mem *skel;
+
+	skel = test_d_path_check_rdonly_mem__open_and_load();
+	ASSERT_ERR_PTR(skel, "unexpected_load_overwriting_rdonly_mem\n");
+
+	test_d_path_check_rdonly_mem__destroy(skel);
+}
+
+void test_d_path(void)
+{
+	if (test__start_subtest("basic"))
+		test_d_path_basic();
+
+	if (test__start_subtest("check_rdonly_mem"))
+		test_d_path_check_rdonly_mem();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c b/tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c
new file mode 100644
index 000000000000..27c27cff6a3a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c
@@ -0,0 +1,28 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Google */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern const int bpf_prog_active __ksym;
+
+SEC("fentry/security_inode_getattr")
+int BPF_PROG(d_path_check_rdonly_mem, struct path *path, struct kstat *stat,
+	     __u32 request_mask, unsigned int query_flags)
+{
+	void *active;
+	__u32 cpu;
+
+	cpu = bpf_get_smp_processor_id();
+	active = (void *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
+	if (active) {
+		/* FAIL here! 'active' points to readonly memory. bpf helpers
+		 * that update its arguments can not write into it.
+		 */
+		bpf_d_path(path, active, sizeof(int));
+	}
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";