From: Hans-Gert Dahmen <hans-gert.dahmen@immu.ne>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, philipp.deppenwiese@immu.ne,
Hans-Gert Dahmen <hans-gert.dahmen@immu.ne>
Subject: [PATCH] firmware: export x86_64 platform flash bios region via sysfs
Date: Fri, 18 Jun 2021 18:47:18 +0200 [thread overview]
Message-ID: <20210618164718.37866-1-hans-gert.dahmen@immu.ne> (raw)
Make the 16MiB long memory-mapped BIOS region of the platform SPI flash
on X86_64 system available via /sys/kernel/firmware/flash_mmap/bios_region
for pen-testing, security analysis and malware detection on kernels
which restrict module loading and/or access to /dev/mem.
It will be used by the open source Converged Security Suite.
https://github.com/9elements/converged-security-suite
Signed-off-by: Hans-Gert Dahmen <hans-gert.dahmen@immu.ne>
---
drivers/firmware/Kconfig | 9 ++++
drivers/firmware/Makefile | 1 +
drivers/firmware/x86_64_flash_mmap.c | 65 ++++++++++++++++++++++++++++
3 files changed, 75 insertions(+)
create mode 100644 drivers/firmware/x86_64_flash_mmap.c
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index db0ea2d2d75a..bd77ca2b4fa6 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -296,6 +296,15 @@ config TURRIS_MOX_RWTM
other manufacturing data and also utilize the Entropy Bit Generator
for hardware random number generation.
+config X86_64_FLASH_MMAP
+ tristate "Export platform flash memory-mapped BIOS region"
+ depends on X86_64
+ help
+ Export the memory-mapped BIOS region of the platform SPI flash as
+ a read-only sysfs binary attribute on X86_64 systems. The first 16MiB
+ will be accessible via /sys/kernel/firmware/flash_mmap/bios_region
+ for security and malware analysis for example.
+
source "drivers/firmware/broadcom/Kconfig"
source "drivers/firmware/google/Kconfig"
source "drivers/firmware/efi/Kconfig"
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 5e013b6a3692..eb7483c5a2ac 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_QCOM_SCM) += qcom_scm.o qcom_scm-smc.o qcom_scm-legacy.o
obj-$(CONFIG_TI_SCI_PROTOCOL) += ti_sci.o
obj-$(CONFIG_TRUSTED_FOUNDATIONS) += trusted_foundations.o
obj-$(CONFIG_TURRIS_MOX_RWTM) += turris-mox-rwtm.o
+obj-$(CONFIG_X86_64_FLASH_MMAP) += x86_64_flash_mmap.o
obj-y += arm_scmi/
obj-y += broadcom/
diff --git a/drivers/firmware/x86_64_flash_mmap.c b/drivers/firmware/x86_64_flash_mmap.c
new file mode 100644
index 000000000000..f9d871a8b516
--- /dev/null
+++ b/drivers/firmware/x86_64_flash_mmap.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Export the memory-mapped BIOS region of the platform SPI flash as
+ * a read-only sysfs binary attribute on X86_64 systems.
+ *
+ * Copyright © 2021 immune GmbH
+ */
+
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+
+#define FLASH_REGION_START 0xFF000000ULL
+#define FLASH_REGION_SIZE 0x1000000ULL
+#define FLASH_REGION_MASK (FLASH_REGION_SIZE - 1)
+
+struct kobject *kobj_ref;
+
+static ssize_t bios_region_read(struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buffer,
+ loff_t offset, size_t count)
+{
+ resource_size_t pa = FLASH_REGION_START + (offset & FLASH_REGION_MASK);
+ void __iomem *va = ioremap(pa, PAGE_SIZE);
+
+ memcpy_fromio(buffer, va, PAGE_SIZE);
+ iounmap(va);
+
+ return min(count, PAGE_SIZE);
+}
+
+BIN_ATTR_RO(bios_region, FLASH_REGION_SIZE);
+
+static int __init flash_mmap_init(void)
+{
+ int ret = 0;
+
+ kobj_ref = kobject_create_and_add("flash_mmap", firmware_kobj);
+ ret = sysfs_create_bin_file(kobj_ref, &bin_attr_bios_region);
+ if (ret) {
+ pr_err("sysfs_create_bin_file failed\n");
+ goto error;
+ }
+
+ return ret;
+
+error:
+ kobject_put(kobj_ref);
+ return ret;
+}
+
+static void __exit flash_mmap_exit(void)
+{
+ sysfs_remove_bin_file(kernel_kobj, &bin_attr_bios_region);
+ kobject_put(kobj_ref);
+}
+
+module_init(flash_mmap_init);
+module_exit(flash_mmap_exit);
+MODULE_DESCRIPTION("Export SPI platform flash memory mapped region via sysfs");
+MODULE_AUTHOR("Hans-Gert Dahmen <hans-gert.dahmen@immu.ne>");
+MODULE_LICENSE("GPL");
--
2.30.2
next reply other threads:[~2021-06-18 16:47 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 16:47 Hans-Gert Dahmen [this message]
2021-06-22 14:23 [PATCH] firmware: export x86_64 platform flash bios region via sysfs Hans-Gert Dahmen
2021-06-22 20:02 ` Greg KH
2021-06-25 13:54 ` Hans-Gert Dahmen
2021-06-22 22:18 ` David Laight
2021-06-23 12:17 ` Hans-Gert Dahmen
2021-06-23 12:40 ` gregkh
2021-06-24 11:20 ` Hans-Gert Dahmen
2021-06-24 11:42 ` gregkh
2021-06-23 13:22 ` David Laight
2021-11-09 0:01 Hans-Gert Dahmen
2021-11-09 6:16 ` Greg KH
2021-11-09 8:52 ` Hans-Gert Dahmen
2021-11-09 8:56 ` Hans-Gert Dahmen
2021-11-09 10:28 ` Greg KH
2021-11-09 12:32 ` Hans-Gert Dahmen
2021-11-09 12:42 ` Greg KH
2021-11-09 14:09 ` Mauro Lima
2021-11-09 14:11 ` Mauro Lima
2021-11-09 14:10 ` Hans-Gert Dahmen
[not found] ` <CAHp75VfbYsyC=7Ncnex1f_jiwrZhExDF7iy4oSGZgS1cHmsN0Q@mail.gmail.com>
2021-11-10 8:37 ` Hans-Gert Dahmen
2021-11-10 9:04 ` Andy Shevchenko
2021-11-10 9:17 ` Hans-Gert Dahmen
2021-11-10 9:25 ` Andy Shevchenko
2021-11-10 10:00 ` Hans-Gert Dahmen
2021-11-10 13:13 ` Mauro Lima
2021-11-10 16:31 ` Andy Shevchenko
2021-11-10 17:37 ` Mauro Lima
2021-11-11 6:42 ` Mika Westerberg
2021-11-11 8:59 ` Hans-Gert Dahmen
2021-11-11 10:32 ` Mika Westerberg
2021-11-11 10:55 ` Hans-Gert Dahmen
2021-11-11 11:43 ` Greg KH
2021-11-11 11:46 ` Richard Hughes
2021-11-11 12:46 ` Andy Shevchenko
2021-11-11 12:56 ` Hans-Gert Dahmen
2021-11-11 13:54 ` Andy Shevchenko
2021-11-11 14:33 ` Hans-Gert Dahmen
2021-11-11 15:30 ` Andy Shevchenko
2021-11-11 15:43 ` Ard Biesheuvel
2021-11-11 15:49 ` Andy Shevchenko
2021-11-11 16:05 ` Hans-Gert Dahmen
2021-11-11 21:07 ` Richard Hughes
2021-11-12 6:52 ` Greg KH
2021-11-12 10:09 ` Richard Hughes
2021-11-12 10:43 ` Greg KH
2021-11-12 12:25 ` Hans-Gert Dahmen
2021-11-11 16:07 ` Hans-Gert Dahmen
2021-11-11 16:44 ` Andy Shevchenko
2021-11-11 16:55 ` Hans-Gert Dahmen
2021-11-11 17:48 ` Andy Shevchenko
2021-11-11 18:14 ` Hans-Gert Dahmen
2021-11-11 19:14 ` Ard Biesheuvel
2021-11-11 20:50 ` Hans-Gert Dahmen
2021-11-11 13:00 ` Mika Westerberg
2021-11-11 13:22 ` Richard Hughes
2021-11-11 13:34 ` Mika Westerberg
2021-11-11 13:36 ` Hans-Gert Dahmen
2021-11-11 14:42 ` Mauro Lima
2021-11-11 15:06 ` Mika Westerberg
2021-11-11 15:16 ` Hans-Gert Dahmen
2021-11-12 6:59 ` Mika Westerberg
2021-11-11 15:31 ` Mauro Lima
2021-11-11 11:50 ` Mauro Lima
2021-11-10 17:41 ` Hans-Gert Dahmen
[not found] ` <E1CBFD23-AC3B-43BF-BF0A-158844486BA9@getmailspring.com>
2021-11-09 10:24 ` Greg KH
2021-11-09 10:30 ` Philipp Deppenwiese
2021-11-09 11:25 ` Greg KH
2021-11-09 13:55 ` Mauro Lima
2021-11-09 16:12 ` Greg KH
2021-11-09 17:23 ` Mauro Lima
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