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Commit 96c4f672 authored by Matthew Garrett's avatar Matthew Garrett Committed by James Morris
Browse files

x86: Lock down IO port access when the kernel is locked down 



IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO
register space. This would potentially permit root to trigger arbitrary
DMA, so lock it down by default.

This also implicitly locks down the KDADDIO, KDDELIO, KDENABIO and
KDDISABIO console ioctls.

Signed-off-by: default avatarMatthew Garrett <mjg59@google.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
cc: x86@kernel.org
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent eb627e17

arch/x86/kernel/ioport.c

+5 −2
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/errno.h>

#include <linux/types.h>

#include <linux/ioport.h>

#include <linux/security.h>

#include <linux/smp.h>

#include <linux/stddef.h>

#include <linux/slab.h>
@@ -31,7 +32,8 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on) 


	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))

		return -EINVAL;

	if (turn_on && !capable(CAP_SYS_RAWIO))

	if (turn_on && (!capable(CAP_SYS_RAWIO) ||

			security_locked_down(LOCKDOWN_IOPORT)))

		return -EPERM;



	/*
@@ -126,7 +128,8 @@ SYSCALL_DEFINE1(iopl, unsigned int, level) 
		return -EINVAL;

	/* Trying to gain more privileges? */

	if (level > old) {

		if (!capable(CAP_SYS_RAWIO))

		if (!capable(CAP_SYS_RAWIO) ||

		    security_locked_down(LOCKDOWN_IOPORT))

			return -EPERM;

	}

	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |

include/linux/security.h

+1 −0
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ enum lockdown_reason { 
	LOCKDOWN_KEXEC,

	LOCKDOWN_HIBERNATION,

	LOCKDOWN_PCI_ACCESS,

	LOCKDOWN_IOPORT,

	LOCKDOWN_INTEGRITY_MAX,

	LOCKDOWN_CONFIDENTIALITY_MAX,

};

security/lockdown/lockdown.c

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { 
	[LOCKDOWN_KEXEC] = "kexec of unsigned images",

	[LOCKDOWN_HIBERNATION] = "hibernation",

	[LOCKDOWN_PCI_ACCESS] = "direct PCI access",

	[LOCKDOWN_IOPORT] = "raw io port access",

	[LOCKDOWN_INTEGRITY_MAX] = "integrity",

	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",

};