Blame Restrict-dev-mem-and-dev-kmem-when-module-loading-is.patch
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From 3dfb34906e9e57e70bd497ee21e8d59325c841d2 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 5bb1985..74ee6a4 100644
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--- a/drivers/char/mem.c
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+++ b/drivers/char/mem.c
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@@ -163,6 +163,9 @@ 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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@@ -515,6 +518,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf,
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if (!pfn_valid(PFN_DOWN(p)))
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return -EIO;
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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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2.7.4
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