76 lines
2.3 KiB
Diff
76 lines
2.3 KiB
Diff
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From: Ben Hutchings <ben@decadent.org.uk>
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Date: Fri, 30 Aug 2019 15:54:24 +0100
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Subject: mtd: phram,slram: Disable when the kernel is locked down
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Forwarded: https://lore.kernel.org/linux-security-module/20190830154720.eekfjt6c4jzvlbfz@decadent.org.uk/
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These drivers allow mapping arbitrary memory ranges as MTD devices.
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This should be disabled to preserve the kernel's integrity when it is
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locked down.
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* Add the HWPARAM flag to the module parameters
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* When slram is built-in, it uses __setup() to read kernel parameters,
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so add an explicit check security_locked_down() check
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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Cc: Matthew Garrett <mjg59@google.com>
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Cc: David Howells <dhowells@redhat.com>
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Cc: Joern Engel <joern@lazybastard.org>
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Cc: linux-mtd@lists.infradead.org
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---
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drivers/mtd/devices/phram.c | 6 +++++-
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drivers/mtd/devices/slram.c | 9 ++++++++-
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2 files changed, 13 insertions(+), 2 deletions(-)
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--- a/drivers/mtd/devices/phram.c
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+++ b/drivers/mtd/devices/phram.c
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@@ -364,7 +364,11 @@ static int phram_param_call(const char *
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#endif
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}
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-module_param_call(phram, phram_param_call, NULL, NULL, 0200);
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+static const struct kernel_param_ops phram_param_ops = {
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+ .set = phram_param_call
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+};
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+__module_param_call(MODULE_PARAM_PREFIX, phram, &phram_param_ops, NULL,
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+ 0200, -1, KERNEL_PARAM_FL_HWPARAM | hwparam_iomem);
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MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
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#ifdef CONFIG_OF
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--- a/drivers/mtd/devices/slram.c
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+++ b/drivers/mtd/devices/slram.c
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@@ -43,6 +43,7 @@
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#include <linux/ioctl.h>
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#include <linux/init.h>
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#include <linux/io.h>
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+#include <linux/security.h>
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#include <linux/mtd/mtd.h>
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@@ -65,7 +66,7 @@ typedef struct slram_mtd_list {
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#ifdef MODULE
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static char *map[SLRAM_MAX_DEVICES_PARAMS];
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-module_param_array(map, charp, NULL, 0);
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+module_param_hw_array(map, charp, iomem, NULL, 0);
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MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
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#else
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static char *map;
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@@ -281,11 +282,17 @@ static int __init init_slram(void)
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#ifndef MODULE
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char *devstart;
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char *devlength;
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+ int ret;
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if (!map) {
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E("slram: not enough parameters.\n");
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return(-EINVAL);
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}
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+
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+ ret = security_locked_down(LOCKDOWN_MODULE_PARAMETERS);
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+ if (ret)
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+ return ret;
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+
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while (map) {
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devname = devstart = devlength = NULL;
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