[v4] Add Intel umip(User Mode Instruction Prevention) basic function tests

Message ID 20190110105856.32422-1-pengfei.xu@intel.com
State Changes Requested
Headers show
Series
  • [v4] Add Intel umip(User Mode Instruction Prevention) basic function tests
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Commit Message

Pengfei Xu Jan. 10, 2019, 10:58 a.m.
umip is a security feature present in new Intel Processors.
  Intel CPU like ICE lake or newer is required.
  When umip enabled, it prevents the execution of certain instructions
  and situation as below:
    when Current Privilege Level (CPL) is greater than 0, user space
    applications could not access to system-wide settings such as
    the global and local descriptor tables, the segment selectors to
    the current task state and the local descriptor table.
  umip is enabled by default at boot.
  umip will protect below instructions in user mode:
    * SGDT - Store Global Descriptor Table
    * SIDT - Store Interrupt Descriptor Table
    * SLDT - Store Local Descriptor Table
    * SMSW - Store Machine Status Word
    * STR  - Store Task Register
  If CPU not support umip, you still could comment cpuinfo check code
  to verify anyway.

Signed-off-by: Pengfei Xu <pengfei.xu@intel.com>
---
 runtest/secure_umip                           |   2 +
 testcases/kernel/security/umip/.gitignore     |   1 +
 testcases/kernel/security/umip/Makefile       |   7 +
 testcases/kernel/security/umip/umip_gp_test.c | 212 ++++++++++++++++++++++++++
 4 files changed, 222 insertions(+)
 create mode 100644 runtest/secure_umip
 create mode 100644 testcases/kernel/security/umip/.gitignore
 create mode 100644 testcases/kernel/security/umip/Makefile
 create mode 100644 testcases/kernel/security/umip/umip_gp_test.c

Comments

Cyril Hrubis Jan. 16, 2019, 1:45 p.m. | #1
Hi!
> +static void sig_handler(int signal)
> +{
> +	int exp_sigsegv = 11;
> +
> +	if (exp_sigsegv == signal) {
> +		sigsegv_cnt++;
> +		tst_res(TPASS, "Received SIGSEGV signal:%d, num:%d",
> +			signal, sigsegv_cnt);
> +		// signal handler by app, kernel will not kill, need exit
> +		exit(EXIT_VALUE);
> +	} else {
> +		tst_res(TWARN, "Received unexpected signal:%d", signal);
> +		SAFE_KILL(pid, SIGINT);
> +	}
> +}

I think I already tried to explain that signal handler runs
asynchronously to the rest of the code and that calling anything else
than a few signal-async-safe functions may cause undefined behavior,
which mostly translates to deadlocks.

Why can't we write the test as:

static void asm_sgdt(void)
{
	unsigned char val[GDT_LEN];

	tst_res(TINFO, "TEST sgdt, sgdt result save at [%p]", val);
	asm volatile("sgdt %0\n" : "=m" (val));
	exit(0);
}

...

static void do_test(unsigned int n)
{
	int pid, status;

	pid = SAFE_FORK();

	if (!pid) {
		switch (n) {
		case 0:
			asm_sgdt();
		break;
		...
		}
	}

	SAFE_WAITPID(pid, &status, 0);

	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSEGV) {
		tst_res(TPASS, "Got SIGSEGV");
		return;
	}

	tst_res(TFAIL, "Child exitted with %s", tst_strstatus(status));
}
Pengfei Xu Jan. 16, 2019, 5:39 p.m. | #2
Hi Cyril,
  Thanks for your advice.
  I make it complex and contain potential risk.

BR.

On 2019-01-16 at 14:45:24 +0100, Cyril Hrubis wrote:
> Hi!
> 
> I think I already tried to explain that signal handler runs
> asynchronously to the rest of the code and that calling anything else
> than a few signal-async-safe functions may cause undefined behavior,
> which mostly translates to deadlocks.
> 
> Why can't we write the test as:
> 
> 	SAFE_WAITPID(pid, &status, 0);
> 
> 	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSEGV) {
> 		tst_res(TPASS, "Got SIGSEGV");
> 		return;
> 	}
> 
> 	tst_res(TFAIL, "Child exitted with %s", tst_strstatus(status));
> }
> 
> 
> -- 
> Cyril Hrubis
> chrubis@suse.cz

Patch

diff --git a/runtest/secure_umip b/runtest/secure_umip
new file mode 100644
index 000000000..4082bc2a3
--- /dev/null
+++ b/runtest/secure_umip
@@ -0,0 +1,2 @@ 
+#DESCRIPTION: CPU security feature UMIP test
+umip_instruction_test umip_gp_test
diff --git a/testcases/kernel/security/umip/.gitignore b/testcases/kernel/security/umip/.gitignore
new file mode 100644
index 000000000..9e7022c59
--- /dev/null
+++ b/testcases/kernel/security/umip/.gitignore
@@ -0,0 +1 @@ 
+umip_gp_test
diff --git a/testcases/kernel/security/umip/Makefile b/testcases/kernel/security/umip/Makefile
new file mode 100644
index 000000000..18896b6f2
--- /dev/null
+++ b/testcases/kernel/security/umip/Makefile
@@ -0,0 +1,7 @@ 
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+top_srcdir		?= ../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/security/umip/umip_gp_test.c b/testcases/kernel/security/umip/umip_gp_test.c
new file mode 100644
index 000000000..d9b1e882e
--- /dev/null
+++ b/testcases/kernel/security/umip/umip_gp_test.c
@@ -0,0 +1,212 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * testcases/security/umip/umip_gp_test.c
+ * Copyright (C) 2018 Intel Corporation
+ * Author: Neri, Ricardo <ricardo.neri@intel.com>
+ *	 Pengfei, Xu   <pengfei.xu@intel.com>
+ */
+
+/*
+ * This test will check if Intel umip(User-Mode Execution Prevention) is
+ * working.
+ *
+ * Intel CPU of ICE lake or newer is required for the test
+ * kconfig requirement:CONFIG_X86_INTEL_UMIP=y
+ *
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#include "tst_test.h"
+#include "tst_safe_stdio.h"
+
+#define CPUINFO_FILE "/proc/cpuinfo"
+
+#define GDT_LEN 10
+#define IDT_LEN 10
+#define EXIT_VALUE 200
+
+static int fd = -1, sigsegv_cnt;
+static pid_t pid;
+
+static struct tcase {
+	enum {
+	sgdt,
+	sidt,
+	sldt,
+	smsw,
+	str
+	} option;
+	int exp_sig;
+} tcases[] = {
+	{sgdt, SIGSEGV},
+	{sidt, SIGSEGV},
+	{sldt, SIGSEGV},
+	{smsw, SIGSEGV},
+	{str, SIGSEGV},
+};
+
+static void asm_sgdt(void)
+{
+	unsigned char val[GDT_LEN];
+
+	memset(val, 0, sizeof(val));
+	tst_res(TINFO, "TEST sgdt, sgdt result save at [%p]", val);
+	asm volatile("sgdt %0\n" : "=m" (val));
+	tst_res(TINFO, "Test sgdt instruction finished");
+}
+
+static void asm_sidt(void)
+{
+	unsigned char val[IDT_LEN];
+
+	memset(val, 0, sizeof(val));
+	tst_res(TINFO, "TEST sidt, sidt result save at [%p]\n", val);
+	asm volatile("sidt %0\n" : "=m" (val));
+	tst_res(TINFO, "Test sidt instruction finished");
+}
+
+static void asm_sldt(void)
+{
+	unsigned long val;
+
+	tst_res(TINFO, "TEST sldt, sldt result save at [%p]\n", &val);
+	asm volatile("sldt %0\n" : "=m" (val));
+	tst_res(TINFO, "Test sldt instruction finished");
+}
+
+static void asm_smsw(void)
+{
+	unsigned long val;
+
+	tst_res(TINFO, "TEST smsw, smsw result save at [%p]\n", &val);
+	asm volatile("smsw %0\n" : "=m" (val));
+	tst_res(TINFO, "Test sidt instruction finished");
+}
+
+static void asm_str(void)
+{
+	unsigned long val;
+
+	tst_res(TINFO, "TEST str, str result save at [%p]\n", &val);
+	asm volatile("str %0\n" : "=m" (val));
+	tst_res(TINFO, "Test str instruction finished");
+}
+
+static void verify_umip_instruction(unsigned int n)
+{
+	int es = -1, status;
+	struct tcase *tc = &tcases[n];
+
+	pid = SAFE_FORK();
+	if (pid == 0) {
+		switch (tc->option) {
+		case 0:
+			asm_sgdt();
+			break;
+		case 1:
+			asm_sidt();
+			break;
+		case 2:
+			asm_sldt();
+			break;
+		case 3:
+			asm_smsw();
+			break;
+		case 4:
+			asm_str();
+			break;
+		default:
+			tst_brk(TCONF, "Invalid tcase parameter:%d",
+				tc->option);
+		}
+	} else {
+		// let child process execute first
+		sleep(1);
+		SAFE_KILL(pid, SIGINT);
+	}
+
+	SAFE_WAITPID(pid, &status, 0);
+
+	if (WIFEXITED(status)) {
+		es = WEXITSTATUS(status);
+		tst_res(TPASS, "Child pid stopped as expected status:%d",
+			status);
+	} else
+		tst_res(TFAIL, "Could not get pid return value");
+	if (es == EXIT_VALUE) {
+		tst_res(TPASS, "Received expected return value %d", es);
+	} else {
+		tst_res(TWARN,
+			"Please confirm kconfig already set CONFIG_X86_INTEL_UMIP=y");
+		tst_res(TFAIL,
+			"Didn't receive SIGSEGV #11, return %d, expect:%d",
+			es, EXIT_VALUE);
+	}
+}
+
+static void sig_handler(int signal)
+{
+	int exp_sigsegv = 11;
+
+	if (exp_sigsegv == signal) {
+		sigsegv_cnt++;
+		tst_res(TPASS, "Received SIGSEGV signal:%d, num:%d",
+			signal, sigsegv_cnt);
+		// signal handler by app, kernel will not kill, need exit
+		exit(EXIT_VALUE);
+	} else {
+		tst_res(TWARN, "Received unexpected signal:%d", signal);
+		SAFE_KILL(pid, SIGINT);
+	}
+}
+
+static void setup(void)
+{
+	FILE *fp;
+	int max = 2048;
+	char buf[max];
+
+	// cpuinfo should contain umip
+	fp = SAFE_FOPEN(CPUINFO_FILE, "r");
+	while (!feof(fp)) {
+		if (fgets(buf, sizeof(buf), fp) == NULL) {
+			tst_brk(TCONF, "cpuinfo show: cpu does not support umip");
+		}
+
+		if (!strstr(buf, "flags"))
+			continue;
+
+		if (strstr(buf, "umip")) {
+			tst_res(TINFO, "cpuinfo contain umip, cpu support umip");
+			break;
+		} else
+			continue;
+	}
+
+	SAFE_FCLOSE(fp);
+	SAFE_SIGNAL(SIGSEGV, sig_handler);
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.min_kver = "4.1",
+	.setup = setup,
+	.tcnt = ARRAY_SIZE(tcases),
+	.forks_child = 1,
+	.test = verify_umip_instruction,
+	.cleanup = cleanup,
+	.needs_root = 1,
+};