This doesn't fully exercise the interaction between KVM and ioperm(),
but it does test basic functionality.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/ioperm.c | 171 +++++++++++++++++++++++++++++++++++
2 files changed, 172 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/ioperm.c
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 8c1cb423cfe6..5743e2966adb 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 test_mremap_vdso \
- check_initial_reg_state sigreturn ldt_gdt iopl \
+ check_initial_reg_state sigreturn ldt_gdt iopl ioperm \
protection_keys test_vdso
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
diff --git a/tools/testing/selftests/x86/ioperm.c b/tools/testing/selftests/x86/ioperm.c
new file mode 100644
index 000000000000..3c4c7feb93af
--- /dev/null
+++ b/tools/testing/selftests/x86/ioperm.c
@@ -0,0 +1,171 @@
+/*
+ * 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 void clearhandler(int sig)
+{
+ struct sigaction sa;
+ memset(&sa, 0, sizeof(sa));
+ sa.sa_handler = SIG_DFL;
+ 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);
+}
+
+static bool try_outb(unsigned short port)
+{
+ sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
+ if (sigsetjmp(jmpbuf, 1) != 0) {
+ return false;
+ } else {
+ asm volatile ("outb %%al, %w[port]"
+ : : [port] "Nd" (port), "a" (0));
+ return true;
+ }
+ clearhandler(SIGSEGV);
+}
+
+static void expect_ok(unsigned short port)
+{
+ if (!try_outb(port)) {
+ printf("[FAIL]\toutb to 0x%02hx failed\n", port);
+ exit(1);
+ }
+
+ printf("[OK]\toutb to 0x%02hx worked\n", port);
+}
+
+static void expect_gp(unsigned short port)
+{
+ if (try_outb(port)) {
+ printf("[FAIL]\toutb to 0x%02hx worked\n", port);
+ exit(1);
+ }
+
+ printf("[OK]\toutb to 0x%02hx failed\n", port);
+}
+
+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");
+
+ expect_gp(0x80);
+ expect_gp(0xed);
+
+ /*
+ * Probe for ioperm support. Note that clearing ioperm bits
+ * works even as nonroot.
+ */
+ printf("[RUN]\tenable 0x80\n");
+ if (ioperm(0x80, 1, 1) != 0) {
+ printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",
+ errno);
+ return 0;
+ }
+ expect_ok(0x80);
+ expect_gp(0xed);
+
+ printf("[RUN]\tdisable 0x80\n");
+ if (ioperm(0x80, 1, 0) != 0) {
+ printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+ return 1;
+ }
+ expect_gp(0x80);
+ expect_gp(0xed);
+
+ /* Make sure that fork() preserves ioperm. */
+ if (ioperm(0x80, 1, 1) != 0) {
+ printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+ return 1;
+ }
+
+ pid_t child = fork();
+ if (child == -1)
+ err(1, "fork");
+
+ if (child == 0) {
+ printf("[RUN]\tchild: check that we inherited permissions\n");
+ expect_ok(0x80);
+ expect_gp(0xed);
+ 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");
+ }
+ }
+
+ /* Test the capability checks. */
+
+ printf("\tDrop privileges\n");
+ if (setresuid(1, 1, 1) != 0) {
+ printf("[WARN]\tDropping privileges failed\n");
+ return 0;
+ }
+
+ printf("[RUN]\tdisable 0x80\n");
+ if (ioperm(0x80, 1, 0) != 0) {
+ printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+ return 1;
+ }
+ printf("[OK]\tit worked\n");
+
+ printf("[RUN]\tenable 0x80 again\n");
+ if (ioperm(0x80, 1, 1) == 0) {
+ printf("[FAIL]\tit succeeded but should have failed.\n");
+ return 1;
+ }
+ printf("[OK]\tit failed\n");
+ return 0;
+}
+
--
2.9.3
