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From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Thu, 8 Mar 2012 10:35:59 -0500
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Subject: [PATCH] x86: Lock down IO port access when module security is enabled
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IO port access would permit users to gain access to PCI configuration
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registers, which in turn (on a lot of hardware) give access to MMIO register
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space. This would potentially permit root to trigger arbitrary DMA, so lock
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it down by default.
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Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
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---
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arch/x86/kernel/ioport.c | 5 +++--
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drivers/char/mem.c | 4 ++++
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2 files changed, 7 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
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index 4ddaf66ea35f..00b440307419 100644
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--- a/arch/x86/kernel/ioport.c
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+++ b/arch/x86/kernel/ioport.c
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@@ -15,6 +15,7 @@
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#include <linux/thread_info.h>
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#include <linux/syscalls.h>
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#include <linux/bitmap.h>
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+#include <linux/module.h>
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#include <asm/syscalls.h>
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/*
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@@ -28,7 +29,7 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
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if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
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return -EINVAL;
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- if (turn_on && !capable(CAP_SYS_RAWIO))
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+ if (turn_on && (!capable(CAP_SYS_RAWIO) || secure_modules()))
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return -EPERM;
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/*
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@@ -103,7 +104,7 @@ SYSCALL_DEFINE1(iopl, unsigned int, level)
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return -EINVAL;
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/* Trying to gain more privileges? */
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if (level > old) {
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- if (!capable(CAP_SYS_RAWIO))
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+ if (!capable(CAP_SYS_RAWIO) || secure_modules())
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return -EPERM;
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}
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regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
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diff --git a/drivers/char/mem.c b/drivers/char/mem.c
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index 297110c12635..efe38c1bc234 100644
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--- a/drivers/char/mem.c
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+++ b/drivers/char/mem.c
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@@ -27,6 +27,7 @@
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#include <linux/export.h>
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#include <linux/io.h>
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#include <linux/aio.h>
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+#include <linux/module.h>
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#include <linux/uaccess.h>
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@@ -577,6 +578,9 @@ static ssize_t write_port(struct file *file, const char __user *buf,
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unsigned long i = *ppos;
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const char __user *tmp = buf;
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+ if (secure_modules())
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+ return -EPERM;
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+
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if (!access_ok(VERIFY_READ, buf, count))
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return -EFAULT;
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while (count-- > 0 && i < 65536) {
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