From: Matthew Garrett <[email protected]> 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 <[email protected]> Signed-off-by: David Howells <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Reviewed-by: "Lee, Chun-Yi" <[email protected]> cc: [email protected] --- 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 9c3cf0944bce..2c0f058651c5 100644 --- a/arch/x86/kernel/ioport.c +++ b/arch/x86/kernel/ioport.c @@ -30,7 +30,8 @@ asmlinkage long sys_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; /* @@ -120,7 +121,8 @@ 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) |
