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authorHao Luo <haoluo@google.com>2022-01-06 12:55:25 -0800
committerAndrii Nakryiko <andrii@kernel.org>2022-01-06 15:20:49 -0800
commit44bab87d8ca6f0544a9f8fc97bdf33aa5b3c899e (patch)
treee88c204993400047827074a50eb71bf3e50319bc
parente59618f0f46fa6cf86d5b82380e0f453756b282b (diff)
downloadlinux-44bab87d8ca6f0544a9f8fc97bdf33aa5b3c899e.tar.bz2
bpf/selftests: Test bpf_d_path on rdonly_mem.
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> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20220106205525.2116218-1-haoluo@google.com
-rw-r--r--tools/testing/selftests/bpf/prog_tests/d_path.c22
-rw-r--r--tools/testing/selftests/bpf/progs/test_d_path_check_rdonly_mem.c28
2 files changed, 49 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/d_path.c b/tools/testing/selftests/bpf/prog_tests/d_path.c
index 0a577a248d34..32fc5b3b5cf6 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 @@ out_close:
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");
+
+ 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";