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 ---
Changes in V8: - Add missing dependency on OF for OF_DYNAMIC
Changes in V7: - Select OF_DYNAMIC when STM32_FIREWALL is set in order to use of_detach_node() in the firewall framework. Since the simple-bus pre-probe creates devices for all subnodes. This function is needed to detach particular nodes so that there's no match
Changes in V6: - Renamed access-controller to access-controllers
Changes in V5: - Rename feature-domain* to access-control* - Fix index out of range in stm32_firewall_get_firewall() - Add mising "select STM32_FIREWALL" in config ARCH_STM32 in arch/arm/mach-stm32/Kconfig
Changes in V4: - Fix documentation syntax - Put node in case of error in stm32_firewall_populate_bus() - Check firewall controller presence before using it in stm32_firewall_controller_register()
Changes in V2: - Support multiple entries for "feature-domains" property. Change stm32_firewall_get_firewall() to do so. - Better handle the device-tree parsing using phandle+args APIs and phandle iterator. - Remove "resource firewall" type - Rephrase STM32_FIREWALL description in the bus Kconfig and remove useless default value - Add missing EXPORT_SYMBOL_GPL - Remove useless stm32_firewall_get_id() API - Add a field for the name of the firewall entry in the stm32_firewall_controller structure - Minor fixes on some traces level (err -> debug) - Fix licenses to GPL-2.0-only - Fix stm32_firewall_get_firewall() description - Rephrase some sentences to better emphasize this is STM32-specific - Switch to list_for_each_entry() in stm32_firewall_controller_unregister() as we only expect one firewall controller instance per device. The loop just breaks when found - Do not register the firewall controller if it is already registered to the framework
MAINTAINERS | 5 + arch/arm/mach-stm32/Kconfig | 1 + arch/arm64/Kconfig.platforms | 1 + drivers/bus/Kconfig | 10 + drivers/bus/Makefile | 1 + drivers/bus/stm32_firewall.c | 294 ++++++++++++++++++++++ drivers/bus/stm32_firewall.h | 83 ++++++ include/linux/bus/stm32_firewall_device.h | 141 +++++++++++ 8 files changed, 536 insertions(+) create mode 100644 drivers/bus/stm32_firewall.c create mode 100644 drivers/bus/stm32_firewall.h create mode 100644 include/linux/bus/stm32_firewall_device.h
diff --git a/MAINTAINERS b/MAINTAINERS index e2c6187a3ac8..774c7e1601d8 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20430,6 +20430,11 @@ 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 diff --git a/arch/arm/mach-stm32/Kconfig b/arch/arm/mach-stm32/Kconfig index 98145031586f..ae21a9f78f9c 100644 --- a/arch/arm/mach-stm32/Kconfig +++ b/arch/arm/mach-stm32/Kconfig @@ -12,6 +12,7 @@ menuconfig ARCH_STM32 select PINCTRL select RESET_CONTROLLER select STM32_EXTI + select STM32_FIREWALL help Support for STMicroelectronics STM32 processors.
diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms index 24335565bad5..13ed0a483617 100644 --- a/arch/arm64/Kconfig.platforms +++ b/arch/arm64/Kconfig.platforms @@ -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: diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index e6742998f372..7d47e0005cfe 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -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 diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index d90eed189a65..fc0511450ec2 100644 --- a/drivers/bus/Makefile +++ b/drivers/bus/Makefile @@ -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 diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c new file mode 100644 index 000000000000..decb79449047 --- /dev/null +++ b/drivers/bus/stm32_firewall.c @@ -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); diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h new file mode 100644 index 000000000000..e5fac85fe346 --- /dev/null +++ b/drivers/bus/stm32_firewall.h @@ -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 */ diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h new file mode 100644 index 000000000000..bbbee0b24ea8 --- /dev/null +++ b/include/linux/bus/stm32_firewall_device.h @@ -0,0 +1,141 @@ +/* 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) +{ + 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 */