This patch add three testcases to verify the proper management of
return_instance data by uretprobes:
- uretprobe_longjmp() verifies that longjmp() bypasses the uretprobe BPF
program attached to the exit of instrumented function.
- uretprobe_cleanup_return_instance() verifies that uretprobe reclaim
the return_instances data created before a longjmp(), which leads to
kernel recount the nested depth of instrumented function.
- uretprobe_reach_nestedness_limit() confirms that the uretprobe doesn't
reclaim the return_instances data created before longjmp() and hijack
the return address of instrumented function upon the nestedness depth
reache the limits (64).
Signed-off-by: Liao Chang <liaochang1@xxxxxxxxxx>
---
.../bpf/prog_tests/uretprobe_depth.c | 150 ++++++++++++++++++
.../selftests/bpf/progs/uretprobe_depth.c | 19 +++
2 files changed, 169 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/uretprobe_depth.c
create mode 100644 tools/testing/selftests/bpf/progs/uretprobe_depth.c
diff --git a/tools/testing/selftests/bpf/prog_tests/uretprobe_depth.c b/tools/testing/selftests/bpf/prog_tests/uretprobe_depth.c
new file mode 100644
index 000000000000..ba03b1868e37
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/uretprobe_depth.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+
+#include <unistd.h>
+#include <setjmp.h>
+#include <asm/ptrace.h>
+#include <linux/compiler.h>
+#include <linux/stringify.h>
+#include "uretprobe_depth.skel.h"
+
+#define RETVAL 0xFFFF
+#define JMPVAL 0x4B1D
+#define MAX_URETPROBE_DEPTH 64 // See include/linux/uprobes.h
+#define NR_OMITTED_URETPROBE 16
+static jmp_buf jmp;
+
+unsigned long __uretprobe_longjmp(int nest, int jmpval, int retval)
+{
+ if (nest) {
+ nest = ++retval < MAX_URETPROBE_DEPTH + NR_OMITTED_URETPROBE;
+ return __uretprobe_longjmp(nest, jmpval, retval);
+ }
+
+ if (jmpval == JMPVAL) {
+ longjmp(jmp, jmpval);
+ return 0;
+ } else
+ return retval;
+}
+
+static void uretprobe_longjmp(void)
+{
+ if (setjmp(jmp) == JMPVAL) {
+ __uretprobe_longjmp(0, 0, JMPVAL);
+ return;
+ }
+
+ __uretprobe_longjmp(0, JMPVAL, RETVAL);
+}
+
+static void uretprobe_cleanup_return_instances(void)
+{
+ if (setjmp(jmp) == JMPVAL) {
+ /*
+ * Cleanup these return instance data created before longjmp
+ * firstly. Then create 16 new return_instance data from here.
+ */
+ __uretprobe_longjmp(1, 0, MAX_URETPROBE_DEPTH);
+ return;
+ }
+
+ /* Create 8 return_instance data from here. */
+ __uretprobe_longjmp(1, JMPVAL,
+ MAX_URETPROBE_DEPTH + NR_OMITTED_URETPROBE / 2);
+}
+
+static void uretprobe_reach_nestedness_limit(void)
+{
+ if (setjmp(jmp) == JMPVAL) {
+ /*
+ * Due to uretprobe reach to the nestedness limit, it doesn't
+ * cleanup the return instance created before longjmp.
+ */
+ __uretprobe_longjmp(1, 0, MAX_URETPROBE_DEPTH);
+ return;
+ }
+
+ /* Create 64 return_instance from here. */
+ __uretprobe_longjmp(1, JMPVAL, 0);
+}
+
+static void test_uretprobe_longjmp(void)
+{
+ struct uretprobe_depth *skel = NULL;
+ int err;
+
+ skel = uretprobe_depth__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "uretprobe_depth__open_and_load"))
+ goto cleanup;
+
+ err = uretprobe_depth__attach(skel);
+ if (!ASSERT_OK(err, "uretprobe_depth__attach"))
+ goto cleanup;
+
+ skel->bss->retval = -1;
+
+ uretprobe_longjmp();
+
+ ASSERT_EQ(skel->bss->retval, JMPVAL, "return value");
+
+cleanup:
+ uretprobe_depth__destroy(skel);
+}
+
+static void test_uretprobe_reach_nestedness_limit(void)
+{
+ struct uretprobe_depth *skel = NULL;
+ int err;
+
+ skel = uretprobe_depth__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "uretprobe_depth__open_and_load"))
+ goto cleanup;
+
+ err = uretprobe_depth__attach(skel);
+ if (!ASSERT_OK(err, "uretprobe_depth__attach"))
+ goto cleanup;
+
+ skel->bss->depth = 0;
+
+ uretprobe_reach_nestedness_limit();
+
+ ASSERT_EQ(skel->bss->depth, 0, "nest depth");
+
+cleanup:
+ uretprobe_depth__destroy(skel);
+}
+
+static void test_uretprobe_cleanup_return_instances(void)
+{
+ struct uretprobe_depth *skel = NULL;
+ int err;
+
+ skel = uretprobe_depth__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "uretprobe_depth__open_and_load"))
+ goto cleanup;
+
+ err = uretprobe_depth__attach(skel);
+ if (!ASSERT_OK(err, "uretprobe_depth__attach"))
+ goto cleanup;
+
+ skel->bss->depth = 0;
+
+ uretprobe_cleanup_return_instances();
+
+ ASSERT_EQ(skel->bss->depth, NR_OMITTED_URETPROBE + 1, "nest depth");
+
+cleanup:
+ uretprobe_depth__destroy(skel);
+}
+
+void test_uretprobe_return_instance(void)
+{
+ if (test__start_subtest("uretprobe_longjmp"))
+ test_uretprobe_longjmp();
+ if (test__start_subtest("uretprobe_cleanup_return_instances"))
+ test_uretprobe_cleanup_return_instances();
+ if (test__start_subtest("uretprobe_reach_nestedness_limit"))
+ test_uretprobe_reach_nestedness_limit();
+}
diff --git a/tools/testing/selftests/bpf/progs/uretprobe_depth.c b/tools/testing/selftests/bpf/progs/uretprobe_depth.c
new file mode 100644
index 000000000000..b71f2de52b5e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uretprobe_depth.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <string.h>
+
+int depth;
+unsigned long retval;
+
+char _license[] SEC("license") = "GPL";
+
+SEC("uretprobe//proc/self/exe:__uretprobe_longjmp")
+int uretprobe(struct pt_regs *ctx)
+{
+ depth++;
+#if defined(__TARGET_ARCH_arm64) || defined(__aarch64__)
+ retval = ctx->regs[0];
+#endif
+ return 0;
+}
--
2.34.1
