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Date: Thu, 17 Mar 2016 02:18:48 -0700
From: tip-bot for Andy Lutomirski <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: andrew.cooper3@...rix.com, dvlasenk@...hat.com,
torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
boris.ostrovsky@...cle.com, luto@...nel.org, peterz@...radead.org,
brgerst@...il.com, mingo@...nel.org, JBeulich@...e.com,
luto@...capital.net, hpa@...or.com, david.vrabel@...rix.com,
tglx@...utronix.de, bp@...en8.de
Subject: [tip:x86/urgent] selftests/x86: Add an iopl test
Commit-ID: b08983015cdddca7e41c95f5054e2a8fb222a264
Gitweb: http://git.kernel.org/tip/b08983015cdddca7e41c95f5054e2a8fb222a264
Author: Andy Lutomirski <luto@...nel.org>
AuthorDate: Wed, 16 Mar 2016 14:14:20 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 17 Mar 2016 09:49:26 +0100
selftests/x86: Add an iopl test
This exercises two cases that are known to be buggy on Xen PV right
now.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David Vrabel <david.vrabel@...rix.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jan Beulich <JBeulich@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/61afe904c95c92abb29cd075b51e10e7feb0f774.1458162709.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/iopl.c | 135 +++++++++++++++++++++++++++++++++++
2 files changed, 136 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index d5ce7d7..b47ebd1 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -5,7 +5,7 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall \
- check_initial_reg_state sigreturn ldt_gdt
+ check_initial_reg_state sigreturn ldt_gdt iopl
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
diff --git a/tools/testing/selftests/x86/iopl.c b/tools/testing/selftests/x86/iopl.c
new file mode 100644
index 0000000..c496ca9
--- /dev/null
+++ b/tools/testing/selftests/x86/iopl.c
@@ -0,0 +1,135 @@
+/*
+ * iopl.c - Test case for a Linux on Xen 64-bit bug
+ * Copyright (c) 2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <sys/io.h>
+
+static int nerrs = 0;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+ int flags)
+{
+ struct sigaction sa;
+ memset(&sa, 0, sizeof(sa));
+ sa.sa_sigaction = handler;
+ sa.sa_flags = SA_SIGINFO | flags;
+ sigemptyset(&sa.sa_mask);
+ if (sigaction(sig, &sa, 0))
+ err(1, "sigaction");
+
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
+{
+ siglongjmp(jmpbuf, 1);
+}
+
+int main(void)
+{
+ cpu_set_t cpuset;
+ CPU_ZERO(&cpuset);
+ CPU_SET(0, &cpuset);
+ if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+ err(1, "sched_setaffinity to CPU 0");
+
+ /* Probe for iopl support. Note that iopl(0) works even as nonroot. */
+ if (iopl(3) != 0) {
+ printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
+ errno);
+ return 0;
+ }
+
+ /* Restore our original state prior to starting the test. */
+ if (iopl(0) != 0)
+ err(1, "iopl(0)");
+
+ pid_t child = fork();
+ if (child == -1)
+ err(1, "fork");
+
+ if (child == 0) {
+ printf("\tchild: set IOPL to 3\n");
+ if (iopl(3) != 0)
+ err(1, "iopl");
+
+ printf("[RUN]\tchild: write to 0x80\n");
+ asm volatile ("outb %%al, $0x80" : : "a" (0));
+
+ return 0;
+ } else {
+ int status;
+ if (waitpid(child, &status, 0) != child ||
+ !WIFEXITED(status)) {
+ printf("[FAIL]\tChild died\n");
+ nerrs++;
+ } else if (WEXITSTATUS(status) != 0) {
+ printf("[FAIL]\tChild failed\n");
+ nerrs++;
+ } else {
+ printf("[OK]\tChild succeeded\n");
+ }
+ }
+
+ printf("[RUN]\tparent: write to 0x80 (should fail)\n");
+
+ sethandler(SIGSEGV, sigsegv, 0);
+ if (sigsetjmp(jmpbuf, 1) != 0) {
+ printf("[OK]\twrite was denied\n");
+ } else {
+ asm volatile ("outb %%al, $0x80" : : "a" (0));
+ printf("[FAIL]\twrite was allowed\n");
+ nerrs++;
+ }
+
+ /* Test the capability checks. */
+ printf("\tiopl(3)\n");
+ if (iopl(3) != 0)
+ err(1, "iopl(3)");
+
+ printf("\tDrop privileges\n");
+ if (setresuid(1, 1, 1) != 0) {
+ printf("[WARN]\tDropping privileges failed\n");
+ goto done;
+ }
+
+ printf("[RUN]\tiopl(3) unprivileged but with IOPL==3\n");
+ if (iopl(3) != 0) {
+ printf("[FAIL]\tiopl(3) should work if iopl is already 3 even if unprivileged\n");
+ nerrs++;
+ }
+
+ printf("[RUN]\tiopl(0) unprivileged\n");
+ if (iopl(0) != 0) {
+ printf("[FAIL]\tiopl(0) should work if iopl is already 3 even if unprivileged\n");
+ nerrs++;
+ }
+
+ printf("[RUN]\tiopl(3) unprivileged\n");
+ if (iopl(3) == 0) {
+ printf("[FAIL]\tiopl(3) should fail if when unprivileged if iopl==0\n");
+ nerrs++;
+ } else {
+ printf("[OK]\tFailed as expected\n");
+ }
+
+done:
+ return nerrs ? 1 : 0;
+}
+
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