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df94a2f1eb
Add support for digital message signing with the private key stored in the MCU. Turris Omnia boards with MKL MCUs have a NIST256p ECDSA private key generated and burned into MCU's flash when manufactured. The private key is not readable from the MCU, but MCU allows for signing messages with it and retrieving the public key. This is exposed to userspace via the keyctl API. In userspace, the user can look at /proc/keys or list the keyring: $ cat /proc/keys 0a3b7cd3 ... keyring .turris-signing-keys: 1 3caf0b1a ... turris-om Turris Omnia SN 0000000A1000023 MCU ECDSA k... $ keyctl rlist %:.turris-signing-keys 1018104602 To get the public key: $ keyctl read 1018104602 33 bytes of data in key: 025d9108 1fb538ae 8435c88b b4379171 d6b158a9 55751b91 1d23e6a9 d017f4b2 1c To sign a message: $ dd if=/dev/urandom of=msg_to_sign bs=32 count=1 $ keyctl pkey_sign 1018104602 0 msg_to_sign >signature Signed-off-by: Marek Behún <kabel@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
163 lines
5 KiB
C
163 lines
5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* CZ.NIC's Turris Omnia MCU driver
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*
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* 2024 by Marek Behún <kabel@kernel.org>
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*/
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#ifndef __TURRIS_OMNIA_MCU_H
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#define __TURRIS_OMNIA_MCU_H
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#include <linux/completion.h>
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#include <linux/gpio/driver.h>
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#include <linux/hw_random.h>
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#include <linux/if_ether.h>
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#include <linux/interrupt.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <linux/watchdog.h>
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#include <linux/workqueue.h>
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enum {
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OMNIA_MCU_CRYPTO_PUBLIC_KEY_LEN = 1 + 32,
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OMNIA_MCU_CRYPTO_SIGNATURE_LEN = 64,
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};
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struct i2c_client;
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struct rtc_device;
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/**
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* struct omnia_mcu - driver private data structure
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* @client: I2C client
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* @type: MCU type (STM32, GD32, MKL, or unknown)
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* @features: bitmap of features supported by the MCU firmware
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* @board_serial_number: board serial number, if stored in MCU
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* @board_first_mac: board first MAC address, if stored in MCU
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* @board_revision: board revision, if stored in MCU
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* @gc: GPIO chip
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* @lock: mutex to protect internal GPIO chip state
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* @mask: bitmap of masked IRQs
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* @rising: bitmap of rising edge IRQs
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* @falling: bitmap of falling edge IRQs
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* @both: bitmap of both edges IRQs
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* @cached: bitmap of cached IRQ line values (when an IRQ line is configured for
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* both edges, we cache the corresponding GPIO values in the IRQ
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* handler)
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* @is_cached: bitmap of which IRQ line values are cached
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* @button_release_emul_work: front button release emulation work, used with old MCU firmware
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* versions which did not send button release events, only button press
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* events
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* @last_status: cached value of the status word, to be compared with new value to
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* determine which interrupt events occurred, used with old MCU
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* firmware versions which only informed that the status word changed,
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* but not which bits of the status word changed
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* @button_pressed_emul: the front button is still emulated to be pressed
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* @rtcdev: RTC device, does not actually count real-time, the device is only
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* used for the RTC alarm mechanism, so that the board can be
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* configured to wake up from poweroff state at a specific time
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* @rtc_alarm: RTC alarm that was set for the board to wake up on, in MCU time
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* (seconds since last MCU reset)
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* @front_button_poweron: the front button should power on the device after it is powered off
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* @wdt: watchdog driver structure
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* @trng: RNG driver structure
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* @trng_entropy_ready: RNG entropy ready completion
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* @msg_signed: message signed completion
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* @sign_lock: mutex to protect message signing state
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* @sign_requested: flag indicating that message signing was requested but not completed
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* @sign_err: message signing error number, filled in interrupt handler
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* @signature: message signing signature, filled in interrupt handler
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* @board_public_key: board public key, if stored in MCU
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*/
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struct omnia_mcu {
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struct i2c_client *client;
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const char *type;
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u32 features;
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u64 board_serial_number;
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u8 board_first_mac[ETH_ALEN];
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u8 board_revision;
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#ifdef CONFIG_TURRIS_OMNIA_MCU_GPIO
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struct gpio_chip gc;
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struct mutex lock;
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unsigned long mask, rising, falling, both, cached, is_cached;
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struct delayed_work button_release_emul_work;
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unsigned long last_status;
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bool button_pressed_emul;
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_SYSOFF_WAKEUP
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struct rtc_device *rtcdev;
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u32 rtc_alarm;
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bool front_button_poweron;
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_WATCHDOG
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struct watchdog_device wdt;
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_TRNG
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struct hwrng trng;
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struct completion trng_entropy_ready;
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_KEYCTL
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struct completion msg_signed;
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struct mutex sign_lock;
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bool sign_requested;
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int sign_err;
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u8 signature[OMNIA_MCU_CRYPTO_SIGNATURE_LEN];
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u8 board_public_key[OMNIA_MCU_CRYPTO_PUBLIC_KEY_LEN];
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#endif
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};
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#ifdef CONFIG_TURRIS_OMNIA_MCU_GPIO
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extern const struct attribute_group omnia_mcu_gpio_group;
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int omnia_mcu_register_gpiochip(struct omnia_mcu *mcu);
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int omnia_mcu_request_irq(struct omnia_mcu *mcu, u32 spec,
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irq_handler_t thread_fn, const char *devname);
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#else
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static inline int omnia_mcu_register_gpiochip(struct omnia_mcu *mcu)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_KEYCTL
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int omnia_mcu_register_keyctl(struct omnia_mcu *mcu);
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#else
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static inline int omnia_mcu_register_keyctl(struct omnia_mcu *mcu)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_SYSOFF_WAKEUP
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extern const struct attribute_group omnia_mcu_poweroff_group;
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int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu);
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#else
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static inline int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_TRNG
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int omnia_mcu_register_trng(struct omnia_mcu *mcu);
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#else
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static inline int omnia_mcu_register_trng(struct omnia_mcu *mcu)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_TURRIS_OMNIA_MCU_WATCHDOG
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int omnia_mcu_register_watchdog(struct omnia_mcu *mcu);
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#else
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static inline int omnia_mcu_register_watchdog(struct omnia_mcu *mcu)
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{
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return 0;
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}
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#endif
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#endif /* __TURRIS_OMNIA_MCU_H */
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