On Tue, 3 Sep 2013, Matthew Garrett wrote:
> 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 <matthew.garr...@nebula.com>
Reviewed-by: James Morris <jmor...@namei.org>
> ---
> 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 <linux/thread_info.h>
> #include <linux/syscalls.h>
> #include <linux/bitmap.h>
> +#include <linux/module.h>
> #include <asm/syscalls.h>
>
> /*
> @@ -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 <linux/export.h>
> #include <linux/io.h>
> #include <linux/aio.h>
> +#include <linux/module.h>
>
> #include <asm/uaccess.h>
>
> @@ -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
>
> --
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>
--
James Morris
<jmor...@namei.org>
--
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