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Message-ID: <5e105b1382cd43d05f1d3a80958e4f50f32144c8.1739894594.git.dvyukov@google.com>
Date: Tue, 18 Feb 2025 17:04:36 +0100
From: Dmitry Vyukov <dvyukov@...gle.com>
To: krisman@...labora.com, tglx@...utronix.de, luto@...nel.org,
peterz@...radead.org, keescook@...omium.org, gregory.price@...verge.com
Cc: Dmitry Vyukov <dvyukov@...gle.com>, Marco Elver <elver@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] selftests: Extend syscall_user_dispatch test to check
allowed range
Add a test that ensures that PR_SET_SYSCALL_USER_DISPATCH respects
the specified allowed PC range. The test includes both a continuous
range and a wrap-around range.
Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Gabriel Krisman Bertazi <krisman@...labora.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Gregory Price <gregory.price@...verge.com>
Cc: Marco Elver <elver@...gle.com>
Cc: linux-kernel@...r.kernel.org
---
.../syscall_user_dispatch/sud_test.c | 79 +++++++++++--------
1 file changed, 48 insertions(+), 31 deletions(-)
diff --git a/tools/testing/selftests/syscall_user_dispatch/sud_test.c b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
index b0969925ec64c..fa40e46e6d3e9 100644
--- a/tools/testing/selftests/syscall_user_dispatch/sud_test.c
+++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
@@ -10,6 +10,7 @@
#include <sys/sysinfo.h>
#include <sys/syscall.h>
#include <signal.h>
+#include <stdbool.h>
#include <asm/unistd.h>
#include "../kselftest_harness.h"
@@ -110,31 +111,15 @@ TEST(bad_prctl_param)
/* PR_SYS_DISPATCH_ON */
op = PR_SYS_DISPATCH_ON;
- /* Dispatcher region is bad (offset > 0 && len == 0) */
- EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, &sel));
- EXPECT_EQ(EINVAL, errno);
- EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, -1L, 0x0, &sel));
- EXPECT_EQ(EINVAL, errno);
+ /* All ranges are allowed */
+ EXPECT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, &sel));
+ EXPECT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, -1L, 0x0, &sel));
+ EXPECT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 1, -1L, &sel));
+ EXPECT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, -1L, 0x1, &sel));
/* Invalid selector */
EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x1, (void *) -1));
EXPECT_EQ(EFAULT, errno);
-
- /*
- * Dispatcher range overflows unsigned long
- */
- EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 1, -1L, &sel));
- EXPECT_EQ(EINVAL, errno) {
- TH_LOG("Should reject bad syscall range");
- }
-
- /*
- * Allowed range overflows usigned long
- */
- EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, -1L, 0x1, &sel));
- EXPECT_EQ(EINVAL, errno) {
- TH_LOG("Should reject bad syscall range");
- }
}
/*
@@ -145,11 +130,13 @@ char glob_sel;
int nr_syscalls_emulated;
int si_code;
int si_errno;
+unsigned long syscall_addr;
static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
{
si_code = info->si_code;
si_errno = info->si_errno;
+ syscall_addr = (unsigned long)info->si_call_addr;
if (info->si_syscall == MAGIC_SYSCALL_1)
nr_syscalls_emulated++;
@@ -172,26 +159,29 @@ static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
#endif
}
-TEST(dispatch_and_return)
+int setup_sigsys_handler(void)
{
- long ret;
struct sigaction act;
sigset_t mask;
- glob_sel = 0;
- nr_syscalls_emulated = 0;
- si_code = 0;
- si_errno = 0;
-
memset(&act, 0, sizeof(act));
sigemptyset(&mask);
-
act.sa_sigaction = handle_sigsys;
act.sa_flags = SA_SIGINFO;
act.sa_mask = mask;
+ return sigaction(SIGSYS, &act, NULL);
+}
- ret = sigaction(SIGSYS, &act, NULL);
- ASSERT_EQ(0, ret);
+TEST(dispatch_and_return)
+{
+ long ret;
+
+ glob_sel = 0;
+ nr_syscalls_emulated = 0;
+ si_code = 0;
+ si_errno = 0;
+
+ ASSERT_EQ(0, setup_sigsys_handler());
/* Make sure selector is good prior to prctl. */
SYSCALL_DISPATCH_OFF(glob_sel);
@@ -321,4 +311,31 @@ TEST(direct_dispatch_range)
}
}
+bool test_range(unsigned long offset, unsigned long length)
+{
+ nr_syscalls_emulated = 0;
+ if (prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, offset, length, &glob_sel))
+ return false;
+ SYSCALL_DISPATCH_ON(glob_sel);
+ return syscall(MAGIC_SYSCALL_1) == MAGIC_SYSCALL_1 && nr_syscalls_emulated == 1;
+}
+
+TEST(dispatch_range)
+{
+ ASSERT_EQ(0, setup_sigsys_handler());
+ ASSERT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &glob_sel));
+ SYSCALL_DISPATCH_ON(glob_sel);
+ ASSERT_EQ(MAGIC_SYSCALL_1, syscall(MAGIC_SYSCALL_1));
+ TH_LOG("syscall_addr=0x%lx", syscall_addr);
+ EXPECT_FALSE(test_range(syscall_addr, 1));
+ EXPECT_FALSE(test_range(syscall_addr-100, 200));
+ EXPECT_TRUE(test_range(syscall_addr+1, 100));
+ EXPECT_TRUE(test_range(syscall_addr-100, 100));
+ /* Wrap-around tests for everything except for a single PC. */
+ EXPECT_TRUE(test_range(syscall_addr+1, -1));
+ EXPECT_FALSE(test_range(syscall_addr, -1));
+ EXPECT_FALSE(test_range(syscall_addr+2, -1));
+ SYSCALL_DISPATCH_OFF(glob_sel);
+}
+
TEST_HARNESS_MAIN
--
2.48.1.601.g30ceb7b040-goog
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