[flashrom-gerrit] Change in flashrom[master]: hwaccess_x86_io: refactor rget_io_perms()

[Nico Huber (Code Review)]

Nico Huber has submitted this change. ( https://review.coreboot.org/c/flashrom/+/61275 )

Change subject: hwaccess_x86_io: refactor rget_io_perms()
......................................................................

hwaccess_x86_io: refactor rget_io_perms()

Abstract the different I/O Port permission methods in own functions.

Change-Id: If4b2f8c2532f3732086ee1d479da6ae6693f9a42
Signed-off-by: Thomas Heijligen 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/61275
Tested-by: build bot (Jenkins) 
Reviewed-by: Edward O'Callaghan 
Reviewed-by: Nico Huber 
Reviewed-by: Angel Pons 
---
M hwaccess_x86_io.c
1 file changed, 98 insertions(+), 50 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Nico Huber: Looks good to me, approved
  Angel Pons: Looks good to me, but someone else must approve
  Edward O'Callaghan: Looks good to me, approved

diff --git a/hwaccess_x86_io.c b/hwaccess_x86_io.c
index 635b27e..e891d98 100644
--- a/hwaccess_x86_io.c
+++ b/hwaccess_x86_io.c
@@ -2,6 +2,8 @@
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2009,2010 Carl-Daniel Hailfinger
+ * Copyright (C) 2022 secunet Security Networks AG
+ * (Written by Thomas Heijligen <[e-mail])
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -14,70 +16,116 @@
  * GNU General Public License for more details.
  */

+/*
+ * This file implements x86 I/O port permission handling.
+ *
+ * For this purpose the platform specific code is encapsuled in two functions
+ * and compiled only on the respective platform. `platform_get_io_perms()` is
+ * called to get the permissions and `platform_release_io_perms()` is called for
+ * releasing those.
+ */
+
 #include <errno.h>
 #include <string.h>
-#if !defined (__DJGPP__) && !defined(__LIBPAYLOAD__)
-/* No file access needed/possible to get hardware access permissions. */
-#include <unistd.h>
-#include <fcntl.h>
-#endif

-#include "hwaccess_x86_io.h"
 #include "flash.h"
+#include "hwaccess_x86_io.h"

-#if USE_IOPERM
-#include <sys/io.h>
-#endif
-
-#if USE_DEV_IO
-int io_fd;
-#endif
-
-#if !(defined(__DJGPP__) || defined(__LIBPAYLOAD__))
-static int release_io_perms(void *p)
+#if defined(__DJGPP__) || defined(__LIBPAYLOAD) /* DJGPP, libpayload */
+static int platform_get_io_perms(void)
 {
-#if defined (__sun)
+	return 0;
+}
+
+static int platform_release_io_perms(void *p)
+{
+	return 0;
+}
+#endif
+
+#if defined(__sun) /* SunOS */
+#include <sys/sysi86.h>
+
+static int platform_get_io_perms(void)
+{
+	return sysi86(SI86V86, V86SC_IOPL, PS_IOPL);
+}
+
+static int platform_release_io_perms(void *p)
+{
    sysi86(SI86V86, V86SC_IOPL, 0);
-#elif USE_DEV_IO
+	return 0;
+}
+#endif
+
+#if USE_DEV_IO /* FreeBSD, DragonFlyBSD */
+#include <fcntl.h>
+#include <unistd.h>
+
+int io_fd;
+
+static int platform_get_io_perms(void)
+{
+	io_fd = open("/dev/io", O_RDWR);
+	return (io_fd >= 0 ? 0 : -1);
+}
+
+static int platform_release_io_perms(void *p)
+{
    close(io_fd);
-#elif USE_IOPERM
+	return 0;
+}
+#endif
+
+#if USE_IOPERM /* GNU Hurd */
+#include <sys/io.h>
+
+static int platform_get_io_perms(void)
+{
+	return ioperm(0, 65536, 1);
+}
+
+static int platform_release_io_perms(void *p)
+{
    ioperm(0, 65536, 0);
-#elif USE_IOPL
+	return 0;
+}
+#endif
+
+#if USE_IOPL /* Linux, Darwin, NetBSD, OpenBSD */
+static int platform_get_io_perms(void)
+{
+	return iopl(3);
+}
+
+static int platform_release_io_perms(void *p)
+{
    iopl(0);
-#endif
    return 0;
 }
+#endif

-/* Get I/O permissions with automatic permission release on shutdown. */
+/**
+ * @brief Get access to the x86 I/O ports
+ *
+ * This function abstracts the platform dependent function to get access to the
+ * x86 I/O ports and musst be called before using IN[B/W/L] or OUT[B/W/L].
+ * It registers a shutdown function to release those privileges.
+ *
+ * @return 0 on success, platform specific number on failure
+ */
 int rget_io_perms(void)
 {
-	#if defined (__sun)
-	if (sysi86(SI86V86, V86SC_IOPL, PS_IOPL) != 0) {
-#elif USE_DEV_IO
-	if ((io_fd = open("/dev/io", O_RDWR)) < 0) {
-#elif USE_IOPERM
-	if (ioperm(0, 65536, 1) != 0) {
-#elif USE_IOPL
-	if (iopl(3) != 0) {
-#endif
-		msg_perr("ERROR: Could not get I/O privileges (%s).\n", strerror(errno));
-		msg_perr("You need to be root.\n");
-		msg_perr("On OpenBSD set securelevel=-1 in /etc/rc.securelevel and\n"
-			 "reboot, or reboot into single user mode.\n");
-		msg_perr("On NetBSD reboot into single user mode or make sure\n"
-			 "that your kernel configuration has the option INSECURE enabled.\n");
-		return 1;
-	} else {
-		register_shutdown(release_io_perms, NULL);
+	if (platform_get_io_perms() == 0) {
+		register_shutdown(platform_release_io_perms, NULL);
+		return 0;
    }
-	return 0;
+	msg_perr("ERROR: Could not get I/O privileges (%s).\n", strerror(errno));
+	msg_perr("Make sure you are root. If you are root, your kernel may still\n"
+		 "prevent access based on security policies.\n");
+	msg_perr("On OpenBSD set securelevel=-1 in /etc/rc.securelevel and\n"
+		 "reboot, or reboot into single user mode.\n");
+	msg_perr("On NetBSD reboot into single user mode or make sure\n"
+		 "that your kernel configuration has the option INSECURE enabled.\n");
+	return 1;
 }
-
-#else
-
-/* DJGPP and libpayload environments have full PCI port I/O permissions by default. */
-int rget_io_perms(void)
-{
-	return 0;
-}
-#endif