linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Gabriel Krisman Bertazi <krisman@collabora.com>
To: tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, kernel@collabora.com,
	willy@infradead.org, luto@kernel.org, gofmanp@gmail.com,
	keescook@chromium.org, linux-kselftest@vger.kernel.org,
	shuah@kernel.org, Gabriel Krisman Bertazi <krisman@collabora.com>
Subject: [PATCH v4 2/2] selftests: Add kselftest for syscall user dispatch
Date: Thu, 16 Jul 2020 15:31:41 -0400	[thread overview]
Message-ID: <20200716193141.4068476-3-krisman@collabora.com> (raw)
In-Reply-To: <20200716193141.4068476-1-krisman@collabora.com>

Implement functionality tests for syscall user dispatch.  In order to
make the test portable, refrain from open coding syscall dispatchers and
calculating glibc memory ranges.

changes since v3:
  - Sort entry in Makefile
  - Add SPDX header
  - Use __NR_syscalls if available

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
---
 tools/testing/selftests/Makefile              |   1 +
 .../syscall_user_dispatch/.gitignore          |   2 +
 .../selftests/syscall_user_dispatch/Makefile  |   9 +
 .../selftests/syscall_user_dispatch/config    |   1 +
 .../syscall_user_dispatch.c                   | 256 ++++++++++++++++++
 5 files changed, 269 insertions(+)
 create mode 100644 tools/testing/selftests/syscall_user_dispatch/.gitignore
 create mode 100644 tools/testing/selftests/syscall_user_dispatch/Makefile
 create mode 100644 tools/testing/selftests/syscall_user_dispatch/config
 create mode 100644 tools/testing/selftests/syscall_user_dispatch/syscall_user_dispatch.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 1195bd85af38..07a3c682f1e4 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -53,6 +53,7 @@ TARGETS += sparc64
 TARGETS += splice
 TARGETS += static_keys
 TARGETS += sync
+TARGETS += syscall_user_dispatch
 TARGETS += sysctl
 TARGETS += timens
 ifneq (1, $(quicktest))
diff --git a/tools/testing/selftests/syscall_user_dispatch/.gitignore b/tools/testing/selftests/syscall_user_dispatch/.gitignore
new file mode 100644
index 000000000000..637f08107add
--- /dev/null
+++ b/tools/testing/selftests/syscall_user_dispatch/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+syscall_user_dispatch
diff --git a/tools/testing/selftests/syscall_user_dispatch/Makefile b/tools/testing/selftests/syscall_user_dispatch/Makefile
new file mode 100644
index 000000000000..eeb07a791057
--- /dev/null
+++ b/tools/testing/selftests/syscall_user_dispatch/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+top_srcdir = ../../../..
+INSTALL_HDR_PATH = $(top_srcdir)/usr
+LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/
+
+CFLAGS += -Wall -I$(LINUX_HDR_PATH)
+
+TEST_GEN_PROGS := syscall_user_dispatch
+include ../lib.mk
diff --git a/tools/testing/selftests/syscall_user_dispatch/config b/tools/testing/selftests/syscall_user_dispatch/config
new file mode 100644
index 000000000000..22c4dfe167ca
--- /dev/null
+++ b/tools/testing/selftests/syscall_user_dispatch/config
@@ -0,0 +1 @@
+CONFIG_SYSCALL_USER_DISPATCH=y
diff --git a/tools/testing/selftests/syscall_user_dispatch/syscall_user_dispatch.c b/tools/testing/selftests/syscall_user_dispatch/syscall_user_dispatch.c
new file mode 100644
index 000000000000..ed783fc447a2
--- /dev/null
+++ b/tools/testing/selftests/syscall_user_dispatch/syscall_user_dispatch.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020 Collabora Ltd.
+ *
+ * Test code for syscall user dispatch
+ */
+
+#define _GNU_SOURCE
+#include <sys/prctl.h>
+#include <sys/sysinfo.h>
+#include <sys/syscall.h>
+#include <signal.h>
+
+#include <asm/unistd.h>
+#include "../kselftest_harness.h"
+
+#ifndef PR_SET_SYSCALL_USER_DISPATCH
+# define PR_SET_SYSCALL_USER_DISPATCH	59
+# define PR_SYS_DISPATCH_OFF	0
+# define PR_SYS_DISPATCH_ON	1
+#endif
+
+#ifndef SYS_USER_DISPATCH
+# define SYS_USER_DISPATCH	2
+#endif
+
+#ifdef __NR_syscalls
+# define MAGIC_SYSCALL_1 (__NR_syscalls + 1) /* Bad Linux syscall number */
+#else
+# define MAGIC_SYSCALL_1 (0xff00)  /* Bad Linux syscall number */
+#endif
+
+#define SYSCALL_DISPATCH_ON(x) ((x) = 1)
+#define SYSCALL_DISPATCH_OFF(x) ((x) = 0)
+
+/* Test Summary:
+ *
+ * - dispatch_trigger_sigsys: Verify if PR_SET_SYSCALL_USER_DISPATCH is
+ *   able to trigger SIGSYS on a syscall.
+ *
+ * - bad_selector: Test that a bad selector value triggers SIGSEGV.
+ *
+ * - bad_prctl_param: Test that the API correctly rejects invalid
+ *   parameters on prctl
+ *
+ * - dispatch_and_return: Test that a syscall is selectively dispatched
+ *   to userspace depending on the value of selector.
+ *
+ * - disable_dispatch: Test that the PR_SYS_DISPATCH_OFF correctly
+ *   disables the dispatcher
+ *
+ * - direct_dispatch_range: Test that a syscall within the allowed range
+ *   can bypass the dispatcher.
+ */
+
+TEST_SIGNAL(dispatch_trigger_sigsys, SIGSYS)
+{
+	char sel = 0;
+	struct sysinfo info;
+	int ret;
+
+	ret = sysinfo(&info);
+	ASSERT_EQ(0, ret);
+
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &sel);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH");
+	}
+
+	SYSCALL_DISPATCH_ON(sel);
+
+	sysinfo(&info);
+
+	EXPECT_FALSE(true) {
+		TH_LOG("Unreachable!");
+	}
+}
+
+TEST_SIGNAL(bad_selector, SIGSEGV)
+{
+	char sel = -1;
+	long ret;
+
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &sel);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH");
+	}
+	EXPECT_FALSE(true) {
+		TH_LOG("Unreachable!");
+	}
+}
+
+TEST(bad_prctl_param)
+{
+	char sel = 0;
+	int op;
+
+	/* Invalid op */
+	op = -1;
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0, 0, &sel);
+	ASSERT_EQ(EINVAL, errno);
+
+	/* PR_SYS_DISPATCH_OFF */
+	op = PR_SYS_DISPATCH_OFF;
+
+	/* start_addr != 0 */
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0xff, 0);
+	EXPECT_EQ(EINVAL, errno);
+
+	/* end_addr != 0 */
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0xff, 0);
+	EXPECT_EQ(EINVAL, errno);
+
+	/* sel != NULL */
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, &sel);
+	EXPECT_EQ(EINVAL, errno);
+
+	/* Valid parameter */
+	errno = 0;
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, 0x0);
+	EXPECT_EQ(0, errno);
+
+	/* PR_SYS_DISPATCH_ON */
+	op = PR_SYS_DISPATCH_ON;
+
+	/* start_addr > end_addr */
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, &sel);
+	EXPECT_EQ(EINVAL, errno);
+
+	/* Invalid selector */
+	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x1, (void *) -1);
+	ASSERT_EQ(EFAULT, errno);
+}
+
+/*
+ * Use global selector for handle_sigsys tests, to avoid passing
+ * selector to signal handler
+ */
+char glob_sel;
+int nr_syscalls_emulated;
+int si_code;
+
+static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
+{
+	si_code = info->si_code;
+
+	if (info->si_syscall == MAGIC_SYSCALL_1)
+		nr_syscalls_emulated++;
+
+	/* In preparation for sigreturn. */
+	SYSCALL_DISPATCH_OFF(glob_sel);
+}
+
+TEST(dispatch_and_return)
+{
+	long ret;
+	struct sigaction act;
+	sigset_t mask;
+
+	glob_sel = 0;
+	nr_syscalls_emulated = 0;
+	si_code = 0;
+
+	memset(&act, 0, sizeof(act));
+	sigemptyset(&mask);
+
+	act.sa_sigaction = handle_sigsys;
+	act.sa_flags = SA_SIGINFO;
+	act.sa_mask = mask;
+
+	ret = sigaction(SIGSYS, &act, NULL);
+	ASSERT_EQ(0, ret);
+
+	/* Make sure selector is good prior to prctl. */
+	SYSCALL_DISPATCH_OFF(glob_sel);
+
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &glob_sel);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH");
+	}
+
+	/* MAGIC_SYSCALL_1 doesn't exist. */
+	SYSCALL_DISPATCH_OFF(glob_sel);
+	ret = syscall(MAGIC_SYSCALL_1);
+	EXPECT_EQ(-1, ret) {
+		TH_LOG("Dispatch triggered unexpectedly");
+	}
+
+	/* MAGIC_SYSCALL_1 should be emulated. */
+	nr_syscalls_emulated = 0;
+	SYSCALL_DISPATCH_ON(glob_sel);
+
+	ret = syscall(MAGIC_SYSCALL_1);
+	EXPECT_EQ(MAGIC_SYSCALL_1, ret) {
+		TH_LOG("Failed to intercept syscall");
+	}
+	EXPECT_EQ(1, nr_syscalls_emulated) {
+		TH_LOG("Failed to emulate syscall");
+	}
+	ASSERT_EQ(SYS_USER_DISPATCH, si_code) {
+		TH_LOG("Bad si_code in SIGSYS");
+	}
+}
+
+TEST(disable_dispatch)
+{
+	int ret;
+	struct sysinfo info;
+	char sel = 0;
+
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &sel);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH");
+	}
+
+	/* MAGIC_SYSCALL_1 doesn't exist. */
+	SYSCALL_DISPATCH_OFF(glob_sel);
+
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_OFF, 0, 0, 0);
+	EXPECT_EQ(0, ret) {
+		TH_LOG("Failed to unset syscall user dispatch");
+	}
+
+	/* Shouldn't have any effect... */
+	SYSCALL_DISPATCH_ON(glob_sel);
+
+	ret = syscall(__NR_sysinfo, &info);
+	EXPECT_EQ(0, ret) {
+		TH_LOG("Dispatch triggered unexpectedly");
+	}
+}
+
+TEST(direct_dispatch_range)
+{
+	int ret = 0;
+	struct sysinfo info;
+	char sel = 0;
+
+	/*
+	 * Instead of calculating libc addresses; allow the entire
+	 * memory map and lock the selector.
+	 */
+	ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, -1L, &sel);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH");
+	}
+
+	SYSCALL_DISPATCH_ON(sel);
+
+	ret = sysinfo(&info);
+	ASSERT_EQ(0, ret) {
+		TH_LOG("Dispatch triggered unexpectedly");
+	}
+}
+
+TEST_HARNESS_MAIN
-- 
2.27.0


  parent reply	other threads:[~2020-07-16 19:32 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 19:31 [PATCH v4 0/2] Syscall User Redirection Gabriel Krisman Bertazi
2020-07-16 19:31 ` [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection Gabriel Krisman Bertazi
2020-07-16 21:06   ` Matthew Wilcox
2020-07-16 21:26     ` Kees Cook
2020-07-17  0:20   ` Andy Lutomirski
2020-07-17  2:15     ` Gabriel Krisman Bertazi
2020-07-17  4:48       ` Andy Lutomirski
2020-07-21 12:06         ` Mark Rutland
2020-07-20  9:23     ` Thomas Gleixner
2020-07-20  9:44       ` Will Deacon
2020-07-20 10:08   ` Thomas Gleixner
2020-07-20 13:46     ` Gabriel Krisman Bertazi
2020-07-16 19:31 ` Gabriel Krisman Bertazi [this message]
2020-07-16 20:04 ` [PATCH v4 0/2] Syscall User Redirection Kees Cook
2020-07-16 20:22   ` Christian Brauner
2020-07-16 20:25     ` Kees Cook
2020-07-16 20:29       ` Christian Brauner
2020-07-16 20:30         ` Gabriel Krisman Bertazi
2020-07-16 21:06           ` Carlos O'Donell
2020-08-02 12:01 ` Pavel Machek
2020-08-04 14:26   ` Gabriel Krisman Bertazi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200716193141.4068476-3-krisman@collabora.com \
    --to=krisman@collabora.com \
    --cc=gofmanp@gmail.com \
    --cc=keescook@chromium.org \
    --cc=kernel@collabora.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=shuah@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH v4 2/2] selftests: Add kselftest for syscall user dispatch' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).