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firewall: introduce stm32_firewall framework

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Introduce a STM32 firewall framework that offers to firewall consumers
different firewall services such as the ability to check their access
rights against their firewall controller(s).

The STM32 firewall framework offers a generic API for STM32 firewall
controllers that is defined in their drivers to best fit the
specificity of each firewall.

There are various types of firewalls:
-Peripheral firewalls that filter accesses to peripherals
-Memory firewalls that filter accesses to memories or memory regions
-No type for undefined type of firewall

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
This commit is contained in:
Gatien Chevallier 2024-01-05 14:03:56 +01:00 committed by Alexandre Torgue
parent c1c67654df
commit 5c9668cfc6
8 changed files with 537 additions and 0 deletions
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5
MAINTAINERS
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@ -20811,6 +20811,11 @@ T: git git://linuxtv.org/media_tree.git
F: Documentation/devicetree/bindings/media/i2c/st,st-mipid02.yaml
F: drivers/media/i2c/st-mipid02.c
ST STM32 FIREWALL
M: Gatien Chevallier <gatien.chevallier@foss.st.com>
S: Maintained
F: drivers/bus/stm32_firewall.c
ST STM32 I2C/SMBUS DRIVER
M: Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
M: Alain Volmat <alain.volmat@foss.st.com>

1
arch/arm/mach-stm32/Kconfig
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@ -12,6 +12,7 @@ menuconfig ARCH_STM32
select PINCTRL
select RESET_CONTROLLER
select STM32_EXTI
select STM32_FIREWALL
help
Support for STMicroelectronics STM32 processors.

1
arch/arm64/Kconfig.platforms
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@ -305,6 +305,7 @@ config ARCH_STM32
select ARM_SMC_MBOX
select ARM_SCMI_PROTOCOL
select COMMON_CLK_SCMI
select STM32_FIREWALL
help
This enables support for ARMv8 based STMicroelectronics
STM32 family, including:

10
drivers/bus/Kconfig
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@ -163,6 +163,16 @@ config QCOM_SSC_BLOCK_BUS
i2c/spi/uart controllers, a hexagon core, and a clock controller
which provides clocks for the above.
config STM32_FIREWALL
bool "STM32 Firewall framework"
depends on (ARCH_STM32 || COMPILE_TEST) && OF
select OF_DYNAMIC
help
Say y to enable STM32 firewall framework and its services. Firewall
controllers will be able to register to the framework. Access for
hardware resources linked to a firewall controller can be requested
through this STM32 framework.
config SUN50I_DE2_BUS
bool "Allwinner A64 DE2 Bus Driver"
default ARM64

1
drivers/bus/Makefile
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@ -26,6 +26,7 @@ obj-$(CONFIG_OMAP_INTERCONNECT) += omap_l3_smx.o omap_l3_noc.o
obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o
obj-$(CONFIG_QCOM_EBI2) += qcom-ebi2.o
obj-$(CONFIG_QCOM_SSC_BLOCK_BUS) += qcom-ssc-block-bus.o
obj-$(CONFIG_STM32_FIREWALL) += stm32_firewall.o
obj-$(CONFIG_SUN50I_DE2_BUS) += sun50i-de2.o
obj-$(CONFIG_SUNXI_RSB) += sunxi-rsb.o
obj-$(CONFIG_OF) += simple-pm-bus.o

294
drivers/bus/stm32_firewall.c Normal file
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@ -0,0 +1,294 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2023, STMicroelectronics - All Rights Reserved
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/bus/stm32_firewall_device.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/slab.h>
#include "stm32_firewall.h"
/* Corresponds to STM32_FIREWALL_MAX_EXTRA_ARGS + firewall ID */
#define STM32_FIREWALL_MAX_ARGS (STM32_FIREWALL_MAX_EXTRA_ARGS + 1)
static LIST_HEAD(firewall_controller_list);
static DEFINE_MUTEX(firewall_controller_list_lock);
/* Firewall device API */
int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
unsigned int nb_firewall)
{
struct stm32_firewall_controller *ctrl;
struct of_phandle_iterator it;
unsigned int i, j = 0;
int err;
if (!firewall || !nb_firewall)
return -EINVAL;
/* Parse property with phandle parsed out */
of_for_each_phandle(&it, err, np, "access-controllers", "#access-controller-cells", 0) {
struct of_phandle_args provider_args;
struct device_node *provider = it.node;
const char *fw_entry;
bool match = false;
if (err) {
pr_err("Unable to get access-controllers property for node %s\n, err: %d",
np->full_name, err);
of_node_put(provider);
return err;
}
if (j > nb_firewall) {
pr_err("Too many firewall controllers");
of_node_put(provider);
return -EINVAL;
}
provider_args.args_count = of_phandle_iterator_args(&it, provider_args.args,
STM32_FIREWALL_MAX_ARGS);
/* Check if the parsed phandle corresponds to a registered firewall controller */
mutex_lock(&firewall_controller_list_lock);
list_for_each_entry(ctrl, &firewall_controller_list, entry) {
if (ctrl->dev->of_node->phandle == it.phandle) {
match = true;
firewall[j].firewall_ctrl = ctrl;
break;
}
}
mutex_unlock(&firewall_controller_list_lock);
if (!match) {
firewall[j].firewall_ctrl = NULL;
pr_err("No firewall controller registered for %s\n", np->full_name);
of_node_put(provider);
return -ENODEV;
}
err = of_property_read_string_index(np, "access-controller-names", j, &fw_entry);
if (err == 0)
firewall[j].entry = fw_entry;
/* Handle the case when there are no arguments given along with the phandle */
if (provider_args.args_count < 0 ||
provider_args.args_count > STM32_FIREWALL_MAX_ARGS) {
of_node_put(provider);
return -EINVAL;
} else if (provider_args.args_count == 0) {
firewall[j].extra_args_size = 0;
firewall[j].firewall_id = U32_MAX;
j++;
continue;
}
/* The firewall ID is always the first argument */
firewall[j].firewall_id = provider_args.args[0];
/* Extra args start at the second argument */
for (i = 0; i < provider_args.args_count - 1; i++)
firewall[j].extra_args[i] = provider_args.args[i + 1];
/* Remove the firewall ID arg that is not an extra argument */
firewall[j].extra_args_size = provider_args.args_count - 1;
j++;
}
return 0;
}
EXPORT_SYMBOL_GPL(stm32_firewall_get_firewall);
int stm32_firewall_grant_access(struct stm32_firewall *firewall)
{
struct stm32_firewall_controller *firewall_controller;
if (!firewall || firewall->firewall_id == U32_MAX)
return -EINVAL;
firewall_controller = firewall->firewall_ctrl;
if (!firewall_controller)
return -ENODEV;
return firewall_controller->grant_access(firewall_controller, firewall->firewall_id);
}
EXPORT_SYMBOL_GPL(stm32_firewall_grant_access);
int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
{
struct stm32_firewall_controller *firewall_controller;
if (!firewall || subsystem_id == U32_MAX || firewall->firewall_id == U32_MAX)
return -EINVAL;
firewall_controller = firewall->firewall_ctrl;
if (!firewall_controller)
return -ENODEV;
return firewall_controller->grant_access(firewall_controller, subsystem_id);
}
EXPORT_SYMBOL_GPL(stm32_firewall_grant_access_by_id);
void stm32_firewall_release_access(struct stm32_firewall *firewall)
{
struct stm32_firewall_controller *firewall_controller;
if (!firewall || firewall->firewall_id == U32_MAX) {
pr_debug("Incorrect arguments when releasing a firewall access\n");
return;
}
firewall_controller = firewall->firewall_ctrl;
if (!firewall_controller) {
pr_debug("No firewall controller to release\n");
return;
}
firewall_controller->release_access(firewall_controller, firewall->firewall_id);
}
EXPORT_SYMBOL_GPL(stm32_firewall_release_access);
void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
{
struct stm32_firewall_controller *firewall_controller;
if (!firewall || subsystem_id == U32_MAX || firewall->firewall_id == U32_MAX) {
pr_debug("Incorrect arguments when releasing a firewall access");
return;
}
firewall_controller = firewall->firewall_ctrl;
if (!firewall_controller) {
pr_debug("No firewall controller to release");
return;
}
firewall_controller->release_access(firewall_controller, subsystem_id);
}
EXPORT_SYMBOL_GPL(stm32_firewall_release_access_by_id);
/* Firewall controller API */
int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller)
{
struct stm32_firewall_controller *ctrl;
if (!firewall_controller)
return -ENODEV;
pr_info("Registering %s firewall controller\n", firewall_controller->name);
mutex_lock(&firewall_controller_list_lock);
list_for_each_entry(ctrl, &firewall_controller_list, entry) {
if (ctrl == firewall_controller) {
pr_debug("%s firewall controller already registered\n",
firewall_controller->name);
mutex_unlock(&firewall_controller_list_lock);
return 0;
}
}
list_add_tail(&firewall_controller->entry, &firewall_controller_list);
mutex_unlock(&firewall_controller_list_lock);
return 0;
}
EXPORT_SYMBOL_GPL(stm32_firewall_controller_register);
void stm32_firewall_controller_unregister(struct stm32_firewall_controller *firewall_controller)
{
struct stm32_firewall_controller *ctrl;
bool controller_removed = false;
if (!firewall_controller) {
pr_debug("Null reference while unregistering firewall controller\n");
return;
}
mutex_lock(&firewall_controller_list_lock);
list_for_each_entry(ctrl, &firewall_controller_list, entry) {
if (ctrl == firewall_controller) {
controller_removed = true;
list_del_init(&ctrl->entry);
break;
}
}
mutex_unlock(&firewall_controller_list_lock);
if (!controller_removed)
pr_debug("There was no firewall controller named %s to unregister\n",
firewall_controller->name);
}
EXPORT_SYMBOL_GPL(stm32_firewall_controller_unregister);
int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
{
struct stm32_firewall *firewalls;
struct device_node *child;
struct device *parent;
unsigned int i;
int len;
int err;
parent = firewall_controller->dev;
dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
for_each_available_child_of_node(dev_of_node(parent), child) {
/* The access-controllers property is mandatory for firewall bus devices */
len = of_count_phandle_with_args(child, "access-controllers",
"#access-controller-cells");
if (len <= 0) {
of_node_put(child);
return -EINVAL;
}
firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
if (!firewalls) {
of_node_put(child);
return -ENOMEM;
}
err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
if (err) {
kfree(firewalls);
of_node_put(child);
return err;
}
for (i = 0; i < len; i++) {
if (firewall_controller->grant_access(firewall_controller,
firewalls[i].firewall_id)) {
/*
* Peripheral access not allowed or not defined.
* Mark the node as populated so platform bus won't probe it
*/
of_detach_node(child);
dev_err(parent, "%s: Device driver will not be probed\n",
child->full_name);
}
}
kfree(firewalls);
}
return 0;
}
EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);

83
drivers/bus/stm32_firewall.h Normal file
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@ -0,0 +1,83 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2023, STMicroelectronics - All Rights Reserved
*/
#ifndef _STM32_FIREWALL_H
#define _STM32_FIREWALL_H
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
/**
* STM32_PERIPHERAL_FIREWALL: This type of firewall protects peripherals
* STM32_MEMORY_FIREWALL: This type of firewall protects memories/subsets of memory
* zones
* STM32_NOTYPE_FIREWALL: Undefined firewall type
*/
#define STM32_PERIPHERAL_FIREWALL BIT(1)
#define STM32_MEMORY_FIREWALL BIT(2)
#define STM32_NOTYPE_FIREWALL BIT(3)
/**
* struct stm32_firewall_controller - Information on firewall controller supplying services
*
* @name: Name of the firewall controller
* @dev: Device reference of the firewall controller
* @mmio: Base address of the firewall controller
* @entry: List entry of the firewall controller list
* @type: Type of firewall
* @max_entries: Number of entries covered by the firewall
* @grant_access: Callback used to grant access for a device access against a
* firewall controller
* @release_access: Callback used to release resources taken by a device when access was
* granted
* @grant_memory_range_access: Callback used to grant access for a device to a given memory region
*/
struct stm32_firewall_controller {
const char *name;
struct device *dev;
void __iomem *mmio;
struct list_head entry;
unsigned int type;
unsigned int max_entries;
int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
size_t size);
};
/**
* stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
* framework
* @firewall_controller: Firewall controller to register
*
* Returns 0 in case of success or -ENODEV if no controller was given.
*/
int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);
/**
* stm32_firewall_controller_unregister - Unregister a firewall controller from the STM32
* firewall framework
* @firewall_controller: Firewall controller to unregister
*/
void stm32_firewall_controller_unregister(struct stm32_firewall_controller *firewall_controller);
/**
* stm32_firewall_populate_bus - Populate device tree nodes that have a correct firewall
* configuration. This is used at boot-time only, as a sanity check
* between device tree and firewalls hardware configurations to
* prevent a kernel crash when a device driver is not granted access
*
* @firewall_controller: Firewall controller which nodes will be populated or not
*
* Returns 0 in case of success or appropriate errno code if error occurred.
*/
int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller);
#endif /* _STM32_FIREWALL_H */

142
include/linux/bus/stm32_firewall_device.h Normal file
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@ -0,0 +1,142 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2023, STMicroelectronics - All Rights Reserved
*/
#ifndef STM32_FIREWALL_DEVICE_H
#define STM32_FIREWALL_DEVICE_H
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#define STM32_FIREWALL_MAX_EXTRA_ARGS 5
/* Opaque reference to stm32_firewall_controller */
struct stm32_firewall_controller;
/**
* struct stm32_firewall - Information on a device's firewall. Each device can have more than one
* firewall.
*
* @firewall_ctrl: Pointer referencing a firewall controller of the device. It is
* opaque so a device cannot manipulate the controller's ops or access
* the controller's data
* @extra_args: Extra arguments that are implementation dependent
* @entry: Name of the firewall entry
* @extra_args_size: Number of extra arguments
* @firewall_id: Firewall ID associated the device for this firewall controller
*/
struct stm32_firewall {
struct stm32_firewall_controller *firewall_ctrl;
u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
const char *entry;
size_t extra_args_size;
u32 firewall_id;
};
#if IS_ENABLED(CONFIG_STM32_FIREWALL)
/**
* stm32_firewall_get_firewall - Get the firewall(s) associated to given device.
* The firewall controller reference is always the first argument
* of each of the access-controller property entries.
* The firewall ID is always the second argument of each of the
* access-controller property entries.
* If there's no argument linked to the phandle, then the firewall ID
* field is set to U32_MAX, which is an invalid ID.
*
* @np: Device node to parse
* @firewall: Array of firewall references
* @nb_firewall: Number of firewall references to get. Must be at least 1.
*
* Returns 0 on success, -ENODEV if there's no match with a firewall controller or appropriate errno
* code if error occurred.
*/
int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
unsigned int nb_firewall);
/**
* stm32_firewall_grant_access - Request firewall access rights and grant access.
*
* @firewall: Firewall reference containing the ID to check against its firewall
* controller
*
* Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
* appropriate errno code if error occurred
*/
int stm32_firewall_grant_access(struct stm32_firewall *firewall);
/**
* stm32_firewall_release_access - Release access granted from a call to
* stm32_firewall_grant_access().
*
* @firewall: Firewall reference containing the ID to check against its firewall
* controller
*/
void stm32_firewall_release_access(struct stm32_firewall *firewall);
/**
* stm32_firewall_grant_access_by_id - Request firewall access rights of a given device
* based on a specific firewall ID
*
* Warnings:
* There is no way to ensure that the given ID will correspond to the firewall referenced in the
* device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
* function must be used with caution.
* This function should be used for subsystem resources that do not have the same firewall ID
* as their parent.
* U32_MAX is an invalid ID.
*
* @firewall: Firewall reference containing the firewall controller
* @subsystem_id: Firewall ID of the subsystem resource
*
* Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
* appropriate errno code if error occurred
*/
int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
/**
* stm32_firewall_release_access_by_id - Release access granted from a call to
* stm32_firewall_grant_access_by_id().
*
* Warnings:
* There is no way to ensure that the given ID will correspond to the firewall referenced in the
* device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
* function must be used with caution.
* This function should be used for subsystem resources that do not have the same firewall ID
* as their parent.
* U32_MAX is an invalid ID.
*
* @firewall: Firewall reference containing the firewall controller
* @subsystem_id: Firewall ID of the subsystem resource
*/
void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
#else /* CONFIG_STM32_FIREWALL */
int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
unsigned int nb_firewall);
{
return -ENODEV;
}
int stm32_firewall_grant_access(struct stm32_firewall *firewall)
{
return -ENODEV;
}
void stm32_firewall_release_access(struct stm32_firewall *firewall)
{
}
int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
{
return -ENODEV;
}
void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
{
}
#endif /* CONFIG_STM32_FIREWALL */
#endif /* STM32_FIREWALL_DEVICE_H */