test: add firmware_class loader test

This provides a simple interface to trigger the firmware_class loader
to test built-in, filesystem, and user helper modes. Additionally adds
tests via the new interface to the selftests tree.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kees Cook 2014-07-14 14:38:12 -07:00 committed by Greg Kroah-Hartman
parent b1425189d0
commit 0a8adf5847
7 changed files with 310 additions and 0 deletions

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@ -1649,6 +1649,19 @@ config TEST_BPF
If unsure, say N.
config TEST_FIRMWARE
tristate "Test firmware loading via userspace interface"
default n
depends on FW_LOADER
help
This builds the "test_firmware" module that creates a userspace
interface for testing firmware loading. This can be used to
control the triggering of firmware loading without needing an
actual firmware-using device. The contents can be rechecked by
userspace.
If unsure, say N.
source "samples/Kconfig"
source "lib/Kconfig.kgdb"

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@ -34,6 +34,7 @@ obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
obj-$(CONFIG_TEST_MODULE) += test_module.o
obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
obj-$(CONFIG_TEST_BPF) += test_bpf.o
obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o
ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG

117
lib/test_firmware.c Normal file
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@ -0,0 +1,117 @@
/*
* This module provides an interface to trigger and test firmware loading.
*
* It is designed to be used for basic evaluation of the firmware loading
* subsystem (for example when validating firmware verification). It lacks
* any extra dependencies, and will not normally be loaded by the system
* unless explicitly requested by name.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/firmware.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
static DEFINE_MUTEX(test_fw_mutex);
static const struct firmware *test_firmware;
static ssize_t test_fw_misc_read(struct file *f, char __user *buf,
size_t size, loff_t *offset)
{
ssize_t rc = 0;
mutex_lock(&test_fw_mutex);
if (test_firmware)
rc = simple_read_from_buffer(buf, size, offset,
test_firmware->data,
test_firmware->size);
mutex_unlock(&test_fw_mutex);
return rc;
}
static const struct file_operations test_fw_fops = {
.owner = THIS_MODULE,
.read = test_fw_misc_read,
};
static struct miscdevice test_fw_misc_device = {
.minor = MISC_DYNAMIC_MINOR,
.name = "test_firmware",
.fops = &test_fw_fops,
};
static ssize_t trigger_request_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int rc;
char *name;
name = kzalloc(count + 1, GFP_KERNEL);
if (!name)
return -ENOSPC;
memcpy(name, buf, count);
pr_info("loading '%s'\n", name);
mutex_lock(&test_fw_mutex);
release_firmware(test_firmware);
test_firmware = NULL;
rc = request_firmware(&test_firmware, name, dev);
if (rc)
pr_info("load of '%s' failed: %d\n", name, rc);
pr_info("loaded: %zu\n", test_firmware ? test_firmware->size : 0);
mutex_unlock(&test_fw_mutex);
kfree(name);
return count;
}
static DEVICE_ATTR_WO(trigger_request);
static int __init test_firmware_init(void)
{
int rc;
rc = misc_register(&test_fw_misc_device);
if (rc) {
pr_err("could not register misc device: %d\n", rc);
return rc;
}
rc = device_create_file(test_fw_misc_device.this_device,
&dev_attr_trigger_request);
if (rc) {
pr_err("could not create sysfs interface: %d\n", rc);
goto dereg;
}
pr_warn("interface ready\n");
return 0;
dereg:
misc_deregister(&test_fw_misc_device);
return rc;
}
module_init(test_firmware_init);
static void __exit test_firmware_exit(void)
{
release_firmware(test_firmware);
device_remove_file(test_fw_misc_device.this_device,
&dev_attr_trigger_request);
misc_deregister(&test_fw_misc_device);
pr_warn("removed interface\n");
}
module_exit(test_firmware_exit);
MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
MODULE_LICENSE("GPL");

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@ -11,6 +11,7 @@ TARGETS += vm
TARGETS += powerpc
TARGETS += user
TARGETS += sysctl
TARGETS += firmware
all:
for TARGET in $(TARGETS); do \

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@ -0,0 +1,27 @@
# Makefile for firmware loading selftests
# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
all:
fw_filesystem:
@if /bin/sh ./fw_filesystem.sh ; then \
echo "fw_filesystem: ok"; \
else \
echo "fw_filesystem: [FAIL]"; \
exit 1; \
fi
fw_userhelper:
@if /bin/sh ./fw_userhelper.sh ; then \
echo "fw_userhelper: ok"; \
else \
echo "fw_userhelper: [FAIL]"; \
exit 1; \
fi
run_tests: all fw_filesystem fw_userhelper
# Nothing to clean up.
clean:
.PHONY: all clean run_tests fw_filesystem fw_userhelper

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@ -0,0 +1,62 @@
#!/bin/sh
# This validates that the kernel will load firmware out of its list of
# firmware locations on disk. Since the user helper does similar work,
# we reset the custom load directory to a location the user helper doesn't
# know so we can be sure we're not accidentally testing the user helper.
set -e
modprobe test_firmware
DIR=/sys/devices/virtual/misc/test_firmware
OLD_TIMEOUT=$(cat /sys/class/firmware/timeout)
OLD_FWPATH=$(cat /sys/module/firmware_class/parameters/path)
FWPATH=$(mktemp -d)
FW="$FWPATH/test-firmware.bin"
test_finish()
{
echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
echo -n "$OLD_PATH" >/sys/module/firmware_class/parameters/path
rm -f "$FW"
rmdir "$FWPATH"
}
trap "test_finish" EXIT
# Turn down the timeout so failures don't take so long.
echo 1 >/sys/class/firmware/timeout
# Set the kernel search path.
echo -n "$FWPATH" >/sys/module/firmware_class/parameters/path
# This is an unlikely real-world firmware content. :)
echo "ABCD0123" >"$FW"
NAME=$(basename "$FW")
# Request a firmware that doesn't exist, it should fail.
echo -n "nope-$NAME" >"$DIR"/trigger_request
if diff -q "$FW" /dev/test_firmware >/dev/null ; then
echo "$0: firmware was not expected to match" >&2
exit 1
else
echo "$0: timeout works"
fi
# This should succeed via kernel load or will fail after 1 second after
# being handed over to the user helper, which won't find the fw either.
if ! echo -n "$NAME" >"$DIR"/trigger_request ; then
echo "$0: could not trigger request" >&2
exit 1
fi
# Verify the contents are what we expect.
if ! diff -q "$FW" /dev/test_firmware >/dev/null ; then
echo "$0: firmware was not loaded" >&2
exit 1
else
echo "$0: filesystem loading works"
fi
exit 0

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@ -0,0 +1,89 @@
#!/bin/sh
# This validates that the kernel will fall back to using the user helper
# to load firmware it can't find on disk itself. We must request a firmware
# that the kernel won't find, and any installed helper (e.g. udev) also
# won't find so that we can do the load ourself manually.
set -e
modprobe test_firmware
DIR=/sys/devices/virtual/misc/test_firmware
OLD_TIMEOUT=$(cat /sys/class/firmware/timeout)
FWPATH=$(mktemp -d)
FW="$FWPATH/test-firmware.bin"
test_finish()
{
echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
rm -f "$FW"
rmdir "$FWPATH"
}
load_fw()
{
local name="$1"
local file="$2"
# This will block until our load (below) has finished.
echo -n "$name" >"$DIR"/trigger_request &
# Give kernel a chance to react.
local timeout=10
while [ ! -e "$DIR"/"$name"/loading ]; do
sleep 0.1
timeout=$(( $timeout - 1 ))
if [ "$timeout" -eq 0 ]; then
echo "$0: firmware interface never appeared" >&2
exit 1
fi
done
echo 1 >"$DIR"/"$name"/loading
cat "$file" >"$DIR"/"$name"/data
echo 0 >"$DIR"/"$name"/loading
# Wait for request to finish.
wait
}
trap "test_finish" EXIT
# This is an unlikely real-world firmware content. :)
echo "ABCD0123" >"$FW"
NAME=$(basename "$FW")
# Test failure when doing nothing (timeout works).
echo 1 >/sys/class/firmware/timeout
echo -n "$NAME" >"$DIR"/trigger_request
if diff -q "$FW" /dev/test_firmware >/dev/null ; then
echo "$0: firmware was not expected to match" >&2
exit 1
else
echo "$0: timeout works"
fi
# Put timeout high enough for us to do work but not so long that failures
# slow down this test too much.
echo 4 >/sys/class/firmware/timeout
# Load this script instead of the desired firmware.
load_fw "$NAME" "$0"
if diff -q "$FW" /dev/test_firmware >/dev/null ; then
echo "$0: firmware was not expected to match" >&2
exit 1
else
echo "$0: firmware comparison works"
fi
# Do a proper load, which should work correctly.
load_fw "$NAME" "$FW"
if ! diff -q "$FW" /dev/test_firmware >/dev/null ; then
echo "$0: firmware was not loaded" >&2
exit 1
else
echo "$0: user helper firmware loading works"
fi
exit 0