path: root/arch/x86/kernel/ioport.c
diff options
authorMatthew Garrett <mjg59@srcf.ucam.org>2019-08-19 17:17:48 -0700
committerJames Morris <jmorris@namei.org>2019-08-19 21:54:16 -0700
commit96c4f67293e4cd8b3394adce5a8041a2784e68a3 (patch)
tree3751173c1272f25476857239381f2c63165ee7cf /arch/x86/kernel/ioport.c
parentPCI: Lock down BAR access when the kernel is locked down (diff)
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: Matthew Garrett <mjg59@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'arch/x86/kernel/ioport.c')
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 0fe1c8782208..61a89d3c0382 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -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) |