From dda201ee7d3bec62b02ee180ccdfae5cb29aad18 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 18 Feb 2019 12:44:59 +0000 Subject: [PATCH] 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 Signed-off-by: David Howells Reviewed-by: Thomas Gleixner Reviewed-by: "Lee, Chun-Yi" cc: x86@kernel.org Gbp-Pq: Topic features/all/lockdown Gbp-Pq: Name 0013-x86-Lock-down-IO-port-access-when-the-kernel-is-lock.patch --- 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 0fe1c878220..abc702a6ae9 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) | -- 2.30.2