125 lines
3.7 KiB
Diff
125 lines
3.7 KiB
Diff
From 4003b9a2c05f4d0d37535c3dffbf4a7b47d5c36c Mon Sep 17 00:00:00 2001
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From: Maarten ter Huurne <maarten@treewalker.org>
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Date: Wed, 8 Sep 2010 02:31:19 +0200
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Subject: [PATCH 09/21] /dev/mem: Add kernel config option to omit this
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device.
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Omitting this device prevents software from accessing the hardware directly, which can cause trouble if the kernel accesses the same hardware.
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It also saves some space on embedded systems.
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---
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arch/x86/Kconfig.debug | 1 +
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drivers/char/Kconfig | 10 ++++++++++
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drivers/char/mem.c | 17 +++++++++++++++++
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3 files changed, 28 insertions(+), 0 deletions(-)
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--- a/arch/x86/Kconfig.debug
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+++ b/arch/x86/Kconfig.debug
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@@ -7,6 +7,7 @@ source "lib/Kconfig.debug"
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config STRICT_DEVMEM
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bool "Filter access to /dev/mem"
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+ depends on DEVMEM
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---help---
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If this option is disabled, you allow userspace (root) access to all
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of memory, including kernel and userspace memory. Accidental
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--- a/drivers/char/Kconfig
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+++ b/drivers/char/Kconfig
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@@ -6,6 +6,16 @@ menu "Character devices"
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source "drivers/tty/Kconfig"
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+config DEVMEM
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+ bool "/dev/mem virtual device support"
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+ default y
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+ help
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+ Say Y here if you want to support the /dev/mem device.
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+ Some X server drivers access the video hardware using this device.
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+ Accessing hardware directly from user space can be useful in some
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+ cases, but it is not without risks.
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+ When in doubt, say "N".
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+
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config DEVKMEM
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bool "/dev/kmem virtual device support"
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default y
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--- a/drivers/char/mem.c
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+++ b/drivers/char/mem.c
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@@ -87,6 +87,8 @@ void __weak unxlate_dev_mem_ptr(unsigned
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{
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}
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+#ifdef CONFIG_DEVMEM
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+
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/*
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* This funcion reads the *physical* memory. The f_pos points directly to the
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* memory location.
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@@ -210,6 +212,10 @@ static ssize_t write_mem(struct file *fi
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return written;
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}
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+#endif
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+
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+#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM)
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+
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int __weak phys_mem_access_prot_allowed(struct file *file,
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unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
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{
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@@ -331,6 +337,8 @@ static int mmap_mem(struct file *file, s
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return 0;
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}
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+#endif
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+
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#ifdef CONFIG_DEVKMEM
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static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
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{
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@@ -694,6 +702,7 @@ static loff_t null_lseek(struct file *fi
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return file->f_pos = 0;
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}
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+#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || defined(CONFIG_DEVPORT)
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/*
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* The memory devices use the full 32/64 bits of the offset, and so we cannot
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* check against negative addresses: they are ok. The return value is weird,
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@@ -726,11 +735,15 @@ static loff_t memory_lseek(struct file *
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mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
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return ret;
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}
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+#endif
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+#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || \
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+ defined(CONFIG_DEVPORT) || defined(CONFIG_CRASH_DUMP)
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static int open_port(struct inode * inode, struct file * filp)
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{
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return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
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}
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+#endif
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#define zero_lseek null_lseek
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#define full_lseek null_lseek
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@@ -740,6 +753,7 @@ static int open_port(struct inode * inod
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#define open_kmem open_mem
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#define open_oldmem open_mem
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+#ifdef CONFIG_DEVMEM
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static const struct file_operations mem_fops = {
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.llseek = memory_lseek,
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.read = read_mem,
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@@ -748,6 +762,7 @@ static const struct file_operations mem_
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.open = open_mem,
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.get_unmapped_area = get_unmapped_area_mem,
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};
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+#endif
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#ifdef CONFIG_DEVKMEM
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static const struct file_operations kmem_fops = {
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@@ -851,7 +866,9 @@ static const struct memdev {
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const struct file_operations *fops;
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struct backing_dev_info *dev_info;
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} devlist[] = {
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+#ifdef CONFIG_DEVMEM
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[1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
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+#endif
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#ifdef CONFIG_DEVKMEM
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[2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
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#endif
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