kernel/Restrict-dev-mem-and-dev-kmem-when-module-loading-is.patch
Josh Boyer 7c202583fc Linux v3.17-rc5-63-gd9773ceabfaf
- Enable infiniband on s390x
2014-09-19 12:40:32 -04:00

43 lines
1.3 KiB
Diff

From 578244241430ea55a7ed2b4ad7b6568c2140fde1 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Fri, 9 Mar 2012 09:28:15 -0500
Subject: [PATCH] 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@nebula.com>
---
drivers/char/mem.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index cdf839f9defe..c63cf93b00eb 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -164,6 +164,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
if (p != *ppos)
return -EFBIG;
+ if (secure_modules())
+ return -EPERM;
+
if (!valid_phys_addr_range(p, count))
return -EFAULT;
@@ -502,6 +505,9 @@ 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);
--
1.9.3