From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH 03/10] x86: Lock down IO port access when module security is enabled Date: Mon, 19 Aug 2013 12:10:12 -0400 Message-ID: <1376928619-3775-3-git-send-email-matthew.garrett@nebula.com> References: <1376928619-3775-1-git-send-email-matthew.garrett@nebula.com> Return-path: In-Reply-To: <1376928619-3775-1-git-send-email-matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jwboyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, Matthew Garrett List-Id: linux-efi@vger.kernel.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. Signed-off-by: Matthew Garrett --- arch/x86/kernel/ioport.c | 5 +++-- drivers/char/mem.c | 4 ++++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c index 4ddaf66..00b4403 100644 --- a/arch/x86/kernel/ioport.c +++ b/arch/x86/kernel/ioport.c @@ -15,6 +15,7 @@ #include #include #include +#include #include /* @@ -28,7 +29,7 @@ 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) || secure_modules())) return -EPERM; /* @@ -103,7 +104,7 @@ 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) || secure_modules()) return -EPERM; } regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); diff --git a/drivers/char/mem.c b/drivers/char/mem.c index f895a8c..1af8664 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -28,6 +28,7 @@ #include #include #include +#include #include @@ -563,6 +564,9 @@ static ssize_t write_port(struct file *file, const char __user *buf, unsigned long i = *ppos; const char __user *tmp = buf; + if (secure_modules()) + return -EPERM; + if (!access_ok(VERIFY_READ, buf, count)) return -EFAULT; while (count-- > 0 && i < 65536) { -- 1.8.3.1