diff mbox series

[12/27] x86: Lock down IO port access when the kernel is locked down

Message ID 20190228231203.212359-12-matthewgarrett@google.com (mailing list archive)
State New, archived
Headers show
Series [PULL,REQUEST] Lock down patches | expand

Commit Message

Matthew Garrett Feb. 28, 2019, 11:11 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@srcf.ucam.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
cc: x86@kernel.org
---
 arch/x86/kernel/ioport.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 0fe1c8782208..abc702a6ae9c 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")))
 		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"))
 			return -EPERM;
 	}
 	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |