>From e492d0a80bb591c34391757f97fc5aa8eb198e4f Mon Sep 17 00:00:00 2001
From: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
Date: Mon, 19 Aug 2013 13:26:07 -0400
Subject: [PATCH 06/13] Restrict /dev/mem and /dev/kmem when module loading is
restricted
Allowing users to write to address space makes it possible for the kernel
to be subverted, avoiding module loading restrictions. Prevent this when
any restrictions have been imposed on loading modules.
Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
---
drivers/char/mem.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1af8664..61406c8 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -159,6 +159,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
unsigned long copied;
void *ptr;
+ if (secure_modules())
+ return -EPERM;
+
if (!valid_phys_addr_range(p, count))
return -EFAULT;
@@ -497,6 +500,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf,
char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
int err = 0;
+ if (secure_modules())
+ return -EPERM;
+
if (p < (unsigned long) high_memory) {
unsigned long to_write = min_t(unsigned long, count,
(unsigned long)high_memory - p);
--
1.8.3.1
_______________________________________________
kernel mailing list
kernel@xxxxxxxxxxxxxxxxxxxxxxx
https://admin.fedoraproject.org/mailman/listinfo/kernel
