From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: [PATCH 10/24] x86: Lock down IO port access when the kernel is locked down Date: Wed, 11 Apr 2018 17:25:44 +0100 Message-ID: <152346394480.4030.1320576522708821046.stgit@warthog.procyon.org.uk> References: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <152346387861.4030.4408662483445703127.stgit@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: torvalds@linux-foundation.org Cc: linux-man@vger.kernel.org, linux-api@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org List-Id: linux-man@vger.kernel.org From: Matthew Garrett 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 Signed-off-by: David Howells Reviewed-by: Thomas Gleixner Reviewed-by: "Lee, Chun-Yi" cc: x86@kernel.org --- arch/x86/kernel/ioport.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) 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) |