Blame Restrict-dev-mem-and-dev-kmem-when-module-loading-is.patch
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From 0e6a3e329c18855d60da298c578c15068af744d8 Mon Sep 17 00:00:00 2001
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From: Matthew Garrett <matthew.garrett@nebula.com>
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Date: Fri, 9 Mar 2012 09:28:15 -0500
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Subject: [PATCH] Restrict /dev/mem and /dev/kmem when module loading is
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restricted
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Allowing users to write to address space makes it possible for the kernel
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to be subverted, avoiding module loading restrictions. Prevent this when
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any restrictions have been imposed on loading modules.
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Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
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---
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drivers/char/mem.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/drivers/char/mem.c b/drivers/char/mem.c
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index cdf839f9defe..c63cf93b00eb 100644
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--- a/drivers/char/mem.c
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+++ b/drivers/char/mem.c
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@@ -164,6 +164,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
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if (p != *ppos)
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return -EFBIG;
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+ if (secure_modules())
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+ return -EPERM;
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+
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if (!valid_phys_addr_range(p, count))
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return -EFAULT;
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@@ -502,6 +505,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf,
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char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
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int err = 0;
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+ if (secure_modules())
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+ return -EPERM;
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+
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if (p < (unsigned long) high_memory) {
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unsigned long to_write = min_t(unsigned long, count,
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(unsigned long)high_memory - p);
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--
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1.9.3
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