diff mbox series

[V31,11/25] x86: Lock down IO port access when the kernel is locked down

Message ID 20190326182742.16950-12-matthewgarrett@google.com (mailing list archive)
State New, archived
Headers show
Series Add support for kernel lockdown | expand

Commit Message

Matthew Garrett March 26, 2019, 6:27 p.m. UTC 
From: Matthew Garrett <mjg59@srcf.ucam.org>

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: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: x86@kernel.org
---
 arch/x86/kernel/ioport.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Andy Lutomirski March 26, 2019, 8:56 p.m. UTC | #1 
On Tue, Mar 26, 2019 at 11:28 AM Matthew Garrett
<matthewgarrett@google.com> wrote:
>
> From: Matthew Garrett <mjg59@srcf.ucam.org>
>
> 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.
>

Reviewed-by: Andy Lutomirski <luto@kernel.org>
diff mbox series

Patch

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 0fe1c8782208..febbd7eb847c 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -31,7 +31,8 @@  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) ||
+			kernel_is_locked_down("ioperm", LOCKDOWN_INTEGRITY)))
 		return -EPERM;
 
 	/*
@@ -126,7 +127,8 @@  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) ||
+		    kernel_is_locked_down("iopl", LOCKDOWN_INTEGRITY))
 			return -EPERM;
 	}
 	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |