[PATCHv8 bpf-next 8/9] selftests/bpf: Add uretprobe shadow stack test

Jiri Olsa
2024-06-11T11:23:43Z

Adding uretprobe shadow stack test that runs all existing
uretprobe tests with shadow stack enabled if it's available.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../selftests/bpf/prog_tests/uprobe_syscall.c | 60 +++++++++++++++++++
1 file changed, 60 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
index 11ccd693ef73..c8517c8f5313 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
@@ -9,6 +9,9 @@
#include <linux/compiler.h>
#include <linux/stringify.h>
#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <sys/prctl.h>
+#include <asm/prctl.h>
#include "uprobe_syscall.skel.h"
#include "uprobe_syscall_executed.skel.h"

@@ -297,6 +300,56 @@ static void test_uretprobe_syscall_call(void)
close(go[1]);
close(go[0]);
}
+
+/*
+ * Borrowed from tools/testing/selftests/x86/test_shadow_stack.c.
+ *
+ * For use in inline enablement of shadow stack.
+ *
+ * The program can't return from the point where shadow stack gets enabled
+ * because there will be no address on the shadow stack. So it can't use
+ * syscall() for enablement, since it is a function.
+ *
+ * Based on code from nolibc.h. Keep a copy here because this can't pull
+ * in all of nolibc.h.
+ */
+#define ARCH_PRCTL(arg1, arg2) \
+({ \
+ long _ret; \
+ register long _num asm("eax") = __NR_arch_prctl; \
+ register long _arg1 asm("rdi") = (long)(arg1); \
+ register long _arg2 asm("rsi") = (long)(arg2); \
+ \
+ asm volatile ( \
+ "syscall\n" \
+ : "=a"(_ret) \
+ : "r"(_arg1), "r"(_arg2), \
+ "0"(_num) \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#ifndef ARCH_SHSTK_ENABLE
+#define ARCH_SHSTK_ENABLE 0x5001
+#define ARCH_SHSTK_DISABLE 0x5002
+#define ARCH_SHSTK_SHSTK (1ULL << 0)
+#endif
+
+static void test_uretprobe_shadow_stack(void)
+{
+ if (ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_SHSTK)) {
+ test__skip();
+ return;
+ }
+
+ /* Run all of the uretprobe tests. */
+ test_uretprobe_regs_equal();
+ test_uretprobe_regs_change();
+ test_uretprobe_syscall_call();
+
+ ARCH_PRCTL(ARCH_SHSTK_DISABLE, ARCH_SHSTK_SHSTK);
+}
#else
static void test_uretprobe_regs_equal(void)
{
@@ -312,6 +365,11 @@ static void test_uretprobe_syscall_call(void)
{
test__skip();
}
+
+static void test_uretprobe_shadow_stack(void)
+{
+ test__skip();
+}
#endif

void test_uprobe_syscall(void)
@@ -322,4 +380,6 @@ void test_uprobe_syscall(void)
test_uretprobe_regs_change();
if (test__start_subtest("uretprobe_syscall_call"))
test_uretprobe_syscall_call();
+ if (test__start_subtest("uretprobe_shadow_stack"))
+ test_uretprobe_shadow_stack();
}
--
2.45.1