diff options
Diffstat (limited to 'security/pfe/pfk_kc.c')
| -rw-r--r-- | security/pfe/pfk_kc.c | 899 |
1 files changed, 899 insertions, 0 deletions
diff --git a/security/pfe/pfk_kc.c b/security/pfe/pfk_kc.c new file mode 100644 index 000000000000..b428e1b8b11c --- /dev/null +++ b/security/pfe/pfk_kc.c @@ -0,0 +1,899 @@ +/* + * Copyright (c) 2015-2017, The Linux Foundation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +/* + * PFK Key Cache + * + * Key Cache used internally in PFK. + * The purpose of the cache is to save access time to QSEE when loading keys. + * Currently the cache is the same size as the total number of keys that can + * be loaded to ICE. Since this number is relatively small, the algorithms for + * cache eviction are simple, linear and based on last usage timestamp, i.e + * the node that will be evicted is the one with the oldest timestamp. + * Empty entries always have the oldest timestamp. + */ + +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <crypto/ice.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/jiffies.h> +#include <linux/slab.h> +#include <linux/printk.h> +#include <linux/sched.h> + +#include "pfk_kc.h" +#include "pfk_ice.h" + + +/** the first available index in ice engine */ +#define PFK_KC_STARTING_INDEX 2 + +/** currently the only supported key and salt sizes */ +#define PFK_KC_KEY_SIZE 32 +#define PFK_KC_SALT_SIZE 32 + +/** Table size */ +/* TODO replace by some constant from ice.h */ +#define PFK_KC_TABLE_SIZE ((32) - (PFK_KC_STARTING_INDEX)) + +/** The maximum key and salt size */ +#define PFK_MAX_KEY_SIZE PFK_KC_KEY_SIZE +#define PFK_MAX_SALT_SIZE PFK_KC_SALT_SIZE +#define PFK_UFS "ufs" + +static DEFINE_SPINLOCK(kc_lock); +static unsigned long flags; +static bool kc_ready; +static char *s_type = "sdcc"; + +/** + * enum pfk_kc_entry_state - state of the entry inside kc table + * + * @FREE: entry is free + * @ACTIVE_ICE_PRELOAD: entry is actively used by ICE engine + and cannot be used by others. SCM call + to load key to ICE is pending to be performed + * @ACTIVE_ICE_LOADED: entry is actively used by ICE engine and + cannot be used by others. SCM call to load the + key to ICE was successfully executed and key is + now loaded + * @INACTIVE_INVALIDATING: entry is being invalidated during file close + and cannot be used by others until invalidation + is complete + * @INACTIVE: entry's key is already loaded, but is not + currently being used. It can be re-used for + optimization and to avoid SCM call cost or + it can be taken by another key if there are + no FREE entries + * @SCM_ERROR: error occurred while scm call was performed to + load the key to ICE + */ +enum pfk_kc_entry_state { + FREE, + ACTIVE_ICE_PRELOAD, + ACTIVE_ICE_LOADED, + INACTIVE_INVALIDATING, + INACTIVE, + SCM_ERROR +}; + +struct kc_entry { + unsigned char key[PFK_MAX_KEY_SIZE]; + size_t key_size; + + unsigned char salt[PFK_MAX_SALT_SIZE]; + size_t salt_size; + + u64 time_stamp; + u32 key_index; + + struct task_struct *thread_pending; + + enum pfk_kc_entry_state state; + + /* ref count for the number of requests in the HW queue for this key */ + int loaded_ref_cnt; + int scm_error; +}; + +static struct kc_entry kc_table[PFK_KC_TABLE_SIZE]; + +/** + * kc_is_ready() - driver is initialized and ready. + * + * Return: true if the key cache is ready. + */ +static inline bool kc_is_ready(void) +{ + return kc_ready; +} + +static inline void kc_spin_lock(void) +{ + spin_lock_irqsave(&kc_lock, flags); +} + +static inline void kc_spin_unlock(void) +{ + spin_unlock_irqrestore(&kc_lock, flags); +} + +/** + * kc_entry_is_available() - checks whether the entry is available + * + * Return true if it is , false otherwise or if invalid + * Should be invoked under spinlock + */ +static bool kc_entry_is_available(const struct kc_entry *entry) +{ + if (!entry) + return false; + + return (entry->state == FREE || entry->state == INACTIVE); +} + +/** + * kc_entry_wait_till_available() - waits till entry is available + * + * Returns 0 in case of success or -ERESTARTSYS if the wait was interrupted + * by signal + * + * Should be invoked under spinlock + */ +static int kc_entry_wait_till_available(struct kc_entry *entry) +{ + int res = 0; + + while (!kc_entry_is_available(entry)) { + set_current_state(TASK_INTERRUPTIBLE); + if (signal_pending(current)) { + res = -ERESTARTSYS; + break; + } + /* assuming only one thread can try to invalidate + * the same entry + */ + entry->thread_pending = current; + kc_spin_unlock(); + schedule(); + kc_spin_lock(); + } + set_current_state(TASK_RUNNING); + + return res; +} + +/** + * kc_entry_start_invalidating() - moves entry to state + * INACTIVE_INVALIDATING + * If entry is in use, waits till + * it gets available + * @entry: pointer to entry + * + * Return 0 in case of success, otherwise error + * Should be invoked under spinlock + */ +static int kc_entry_start_invalidating(struct kc_entry *entry) +{ + int res; + + res = kc_entry_wait_till_available(entry); + if (res) + return res; + + entry->state = INACTIVE_INVALIDATING; + + return 0; +} + +/** + * kc_entry_finish_invalidating() - moves entry to state FREE + * wakes up all the tasks waiting + * on it + * + * @entry: pointer to entry + * + * Return 0 in case of success, otherwise error + * Should be invoked under spinlock + */ +static void kc_entry_finish_invalidating(struct kc_entry *entry) +{ + if (!entry) + return; + + if (entry->state != INACTIVE_INVALIDATING) + return; + + entry->state = FREE; +} + +/** + * kc_min_entry() - compare two entries to find one with minimal time + * @a: ptr to the first entry. If NULL the other entry will be returned + * @b: pointer to the second entry + * + * Return the entry which timestamp is the minimal, or b if a is NULL + */ +static inline struct kc_entry *kc_min_entry(struct kc_entry *a, + struct kc_entry *b) +{ + if (!a) + return b; + + if (time_before64(b->time_stamp, a->time_stamp)) + return b; + + return a; +} + +/** + * kc_entry_at_index() - return entry at specific index + * @index: index of entry to be accessed + * + * Return entry + * Should be invoked under spinlock + */ +static struct kc_entry *kc_entry_at_index(int index) +{ + return &(kc_table[index]); +} + +/** + * kc_find_key_at_index() - find kc entry starting at specific index + * @key: key to look for + * @key_size: the key size + * @salt: salt to look for + * @salt_size: the salt size + * @sarting_index: index to start search with, if entry found, updated with + * index of that entry + * + * Return entry or NULL in case of error + * Should be invoked under spinlock + */ +static struct kc_entry *kc_find_key_at_index(const unsigned char *key, + size_t key_size, const unsigned char *salt, size_t salt_size, + int *starting_index) +{ + struct kc_entry *entry = NULL; + int i = 0; + + for (i = *starting_index; i < PFK_KC_TABLE_SIZE; i++) { + entry = kc_entry_at_index(i); + + if (NULL != salt) { + if (entry->salt_size != salt_size) + continue; + + if (0 != memcmp(entry->salt, salt, salt_size)) + continue; + } + + if (entry->key_size != key_size) + continue; + + if (0 == memcmp(entry->key, key, key_size)) { + *starting_index = i; + return entry; + } + } + + return NULL; +} + +/** + * kc_find_key() - find kc entry + * @key: key to look for + * @key_size: the key size + * @salt: salt to look for + * @salt_size: the salt size + * + * Return entry or NULL in case of error + * Should be invoked under spinlock + */ +static struct kc_entry *kc_find_key(const unsigned char *key, size_t key_size, + const unsigned char *salt, size_t salt_size) +{ + int index = 0; + + return kc_find_key_at_index(key, key_size, salt, salt_size, &index); +} + +/** + * kc_find_oldest_entry_non_locked() - finds the entry with minimal timestamp + * that is not locked + * + * Returns entry with minimal timestamp. Empty entries have timestamp + * of 0, therefore they are returned first. + * If all the entries are locked, will return NULL + * Should be invoked under spin lock + */ +static struct kc_entry *kc_find_oldest_entry_non_locked(void) +{ + struct kc_entry *curr_min_entry = NULL; + struct kc_entry *entry = NULL; + int i = 0; + + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) { + entry = kc_entry_at_index(i); + + if (entry->state == FREE) + return entry; + + if (entry->state == INACTIVE) + curr_min_entry = kc_min_entry(curr_min_entry, entry); + } + + return curr_min_entry; +} + +/** + * kc_update_timestamp() - updates timestamp of entry to current + * + * @entry: entry to update + * + */ +static void kc_update_timestamp(struct kc_entry *entry) +{ + if (!entry) + return; + + entry->time_stamp = get_jiffies_64(); +} + +/** + * kc_clear_entry() - clear the key from entry and mark entry not in use + * + * @entry: pointer to entry + * + * Should be invoked under spinlock + */ +static void kc_clear_entry(struct kc_entry *entry) +{ + if (!entry) + return; + + memset(entry->key, 0, entry->key_size); + memset(entry->salt, 0, entry->salt_size); + + entry->key_size = 0; + entry->salt_size = 0; + + entry->time_stamp = 0; + entry->scm_error = 0; +} + +/** + * kc_update_entry() - replaces the key in given entry and + * loads the new key to ICE + * + * @entry: entry to replace key in + * @key: key + * @key_size: key_size + * @salt: salt + * @salt_size: salt_size + * + * The previous key is securely released and wiped, the new one is loaded + * to ICE. + * Should be invoked under spinlock + */ +static int kc_update_entry(struct kc_entry *entry, const unsigned char *key, + size_t key_size, const unsigned char *salt, size_t salt_size) +{ + int ret; + + kc_clear_entry(entry); + + memcpy(entry->key, key, key_size); + entry->key_size = key_size; + + memcpy(entry->salt, salt, salt_size); + entry->salt_size = salt_size; + + /* Mark entry as no longer free before releasing the lock */ + entry->state = ACTIVE_ICE_PRELOAD; + kc_spin_unlock(); + + ret = qti_pfk_ice_set_key(entry->key_index, entry->key, + entry->salt, s_type); + + kc_spin_lock(); + return ret; +} + +/** + * pfk_kc_init() - init function + * + * Return 0 in case of success, error otherwise + */ +int pfk_kc_init(void) +{ + int i = 0; + struct kc_entry *entry = NULL; + + kc_spin_lock(); + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) { + entry = kc_entry_at_index(i); + entry->key_index = PFK_KC_STARTING_INDEX + i; + } + kc_ready = true; + kc_spin_unlock(); + + return 0; +} + +/** + * pfk_kc_denit() - deinit function + * + * Return 0 in case of success, error otherwise + */ +int pfk_kc_deinit(void) +{ + int res = pfk_kc_clear(); + kc_ready = false; + + return res; +} + +/** + * pfk_kc_load_key_start() - retrieve the key from cache or add it if + * it's not there and return the ICE hw key index in @key_index. + * @key: pointer to the key + * @key_size: the size of the key + * @salt: pointer to the salt + * @salt_size: the size of the salt + * @key_index: the pointer to key_index where the output will be stored + * @async: whether scm calls are allowed in the caller context + * + * If key is present in cache, than the key_index will be retrieved from cache. + * If it is not present, the oldest entry from kc table will be evicted, + * the key will be loaded to ICE via QSEE to the index that is the evicted + * entry number and stored in cache. + * Entry that is going to be used is marked as being used, it will mark + * as not being used when ICE finishes using it and pfk_kc_load_key_end + * will be invoked. + * As QSEE calls can only be done from a non-atomic context, when @async flag + * is set to 'false', it specifies that it is ok to make the calls in the + * current context. Otherwise, when @async is set, the caller should retry the + * call again from a different context, and -EAGAIN error will be returned. + * + * Return 0 in case of success, error otherwise + */ +int pfk_kc_load_key_start(const unsigned char *key, size_t key_size, + const unsigned char *salt, size_t salt_size, u32 *key_index, + bool async) +{ + int ret = 0; + struct kc_entry *entry = NULL; + bool entry_exists = false; + + if (!kc_is_ready()) + return -ENODEV; + + if (!key || !salt || !key_index) + return -EINVAL; + + if (key_size != PFK_KC_KEY_SIZE) { + pr_err("unsupported key size %zu\n", key_size); + return -EINVAL; + } + + if (salt_size != PFK_KC_SALT_SIZE) { + pr_err("unsupported salt size %zu\n", salt_size); + return -EINVAL; + } + + kc_spin_lock(); + + entry = kc_find_key(key, key_size, salt, salt_size); + if (!entry) { + if (async) { + pr_debug("found empty entry, a separate task will populate it\n"); + kc_spin_unlock(); + return -EAGAIN; + } + + entry = kc_find_oldest_entry_non_locked(); + if (!entry) { + /* could not find a single non locked entry, + * return EBUSY to upper layers so that the + * request will be rescheduled + */ + kc_spin_unlock(); + return -EBUSY; + } + } else { + entry_exists = true; + } + + pr_debug("entry with index %d is in state %d\n", + entry->key_index, entry->state); + + switch (entry->state) { + case (INACTIVE): + if (entry_exists) { + kc_update_timestamp(entry); + entry->state = ACTIVE_ICE_LOADED; + + if (!strcmp(s_type, (char *)PFK_UFS)) { + if (async) + entry->loaded_ref_cnt++; + } else { + entry->loaded_ref_cnt++; + } + break; + } + case (FREE): + ret = kc_update_entry(entry, key, key_size, salt, salt_size); + if (ret) { + entry->state = SCM_ERROR; + entry->scm_error = ret; + pr_err("%s: key load error (%d)\n", __func__, ret); + } else { + kc_update_timestamp(entry); + entry->state = ACTIVE_ICE_LOADED; + + /* + * In case of UFS only increase ref cnt for async calls, + * sync calls from within work thread do not pass + * requests further to HW + */ + if (!strcmp(s_type, (char *)PFK_UFS)) { + if (async) + entry->loaded_ref_cnt++; + } else { + entry->loaded_ref_cnt++; + } + } + break; + case (ACTIVE_ICE_PRELOAD): + case (INACTIVE_INVALIDATING): + ret = -EAGAIN; + break; + case (ACTIVE_ICE_LOADED): + kc_update_timestamp(entry); + + if (!strcmp(s_type, (char *)PFK_UFS)) { + if (async) + entry->loaded_ref_cnt++; + } else { + entry->loaded_ref_cnt++; + } + break; + case(SCM_ERROR): + ret = entry->scm_error; + kc_clear_entry(entry); + entry->state = FREE; + break; + default: + pr_err("invalid state %d for entry with key index %d\n", + entry->state, entry->key_index); + ret = -EINVAL; + } + + *key_index = entry->key_index; + kc_spin_unlock(); + + return ret; +} + +/** + * pfk_kc_load_key_end() - finish the process of key loading that was started + * by pfk_kc_load_key_start + * by marking the entry as not + * being in use + * @key: pointer to the key + * @key_size: the size of the key + * @salt: pointer to the salt + * @salt_size: the size of the salt + * + */ +void pfk_kc_load_key_end(const unsigned char *key, size_t key_size, + const unsigned char *salt, size_t salt_size) +{ + struct kc_entry *entry = NULL; + struct task_struct *tmp_pending = NULL; + int ref_cnt = 0; + + if (!kc_is_ready()) + return; + + if (!key || !salt) + return; + + if (key_size != PFK_KC_KEY_SIZE) + return; + + if (salt_size != PFK_KC_SALT_SIZE) + return; + + kc_spin_lock(); + + entry = kc_find_key(key, key_size, salt, salt_size); + if (!entry) { + kc_spin_unlock(); + pr_err("internal error, there should an entry to unlock\n"); + + return; + } + ref_cnt = --entry->loaded_ref_cnt; + + if (ref_cnt < 0) + pr_err("internal error, ref count should never be negative\n"); + + if (!ref_cnt) { + entry->state = INACTIVE; + /* + * wake-up invalidation if it's waiting + * for the entry to be released + */ + if (entry->thread_pending) { + tmp_pending = entry->thread_pending; + entry->thread_pending = NULL; + + kc_spin_unlock(); + wake_up_process(tmp_pending); + return; + } + } + + kc_spin_unlock(); +} + +/** + * pfk_kc_remove_key() - remove the key from cache and from ICE engine + * @key: pointer to the key + * @key_size: the size of the key + * @salt: pointer to the key + * @salt_size: the size of the key + * + * Return 0 in case of success, error otherwise (also in case of non + * (existing key) + */ +int pfk_kc_remove_key_with_salt(const unsigned char *key, size_t key_size, + const unsigned char *salt, size_t salt_size) +{ + struct kc_entry *entry = NULL; + int res = 0; + + if (!kc_is_ready()) + return -ENODEV; + + if (!key) + return -EINVAL; + + if (!salt) + return -EINVAL; + + if (key_size != PFK_KC_KEY_SIZE) + return -EINVAL; + + if (salt_size != PFK_KC_SALT_SIZE) + return -EINVAL; + + kc_spin_lock(); + + entry = kc_find_key(key, key_size, salt, salt_size); + if (!entry) { + pr_debug("%s: key does not exist\n", __func__); + kc_spin_unlock(); + return -EINVAL; + } + + res = kc_entry_start_invalidating(entry); + if (res != 0) { + kc_spin_unlock(); + return res; + } + kc_clear_entry(entry); + + kc_spin_unlock(); + + qti_pfk_ice_invalidate_key(entry->key_index, s_type); + + kc_spin_lock(); + kc_entry_finish_invalidating(entry); + kc_spin_unlock(); + + return 0; +} + +/** + * pfk_kc_remove_key() - remove the key from cache and from ICE engine + * when no salt is available. Will only search key part, if there are several, + * all will be removed + * + * @key: pointer to the key + * @key_size: the size of the key + * + * Return 0 in case of success, error otherwise (also for non-existing key) + */ +int pfk_kc_remove_key(const unsigned char *key, size_t key_size) +{ + struct kc_entry *entry = NULL; + int index = 0; + int temp_indexes[PFK_KC_TABLE_SIZE] = {0}; + int temp_indexes_size = 0; + int i = 0; + int res = 0; + + if (!kc_is_ready()) + return -ENODEV; + + if (!key) + return -EINVAL; + + if (key_size != PFK_KC_KEY_SIZE) + return -EINVAL; + + memset(temp_indexes, -1, sizeof(temp_indexes)); + + kc_spin_lock(); + + entry = kc_find_key_at_index(key, key_size, NULL, 0, &index); + if (!entry) { + pr_err("%s: key does not exist\n", __func__); + kc_spin_unlock(); + return -EINVAL; + } + + res = kc_entry_start_invalidating(entry); + if (res != 0) { + kc_spin_unlock(); + return res; + } + + temp_indexes[temp_indexes_size++] = index; + kc_clear_entry(entry); + + /* let's clean additional entries with the same key if there are any */ + do { + index++; + entry = kc_find_key_at_index(key, key_size, NULL, 0, &index); + if (!entry) + break; + + res = kc_entry_start_invalidating(entry); + if (res != 0) { + kc_spin_unlock(); + goto out; + } + + temp_indexes[temp_indexes_size++] = index; + + kc_clear_entry(entry); + + + } while (true); + + kc_spin_unlock(); + + temp_indexes_size--; + for (i = temp_indexes_size; i >= 0 ; i--) + qti_pfk_ice_invalidate_key( + kc_entry_at_index(temp_indexes[i])->key_index, + s_type); + + /* fall through */ + res = 0; + +out: + kc_spin_lock(); + for (i = temp_indexes_size; i >= 0 ; i--) + kc_entry_finish_invalidating( + kc_entry_at_index(temp_indexes[i])); + kc_spin_unlock(); + + return res; +} + +/** + * pfk_kc_clear() - clear the table and remove all keys from ICE + * + * Return 0 on success, error otherwise + * + */ +int pfk_kc_clear(void) +{ + struct kc_entry *entry = NULL; + int i = 0; + int res = 0; + + if (!kc_is_ready()) + return -ENODEV; + + kc_spin_lock(); + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) { + entry = kc_entry_at_index(i); + res = kc_entry_start_invalidating(entry); + if (res != 0) { + kc_spin_unlock(); + goto out; + } + kc_clear_entry(entry); + } + kc_spin_unlock(); + + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) + qti_pfk_ice_invalidate_key(kc_entry_at_index(i)->key_index, + s_type); + + /* fall through */ + res = 0; +out: + kc_spin_lock(); + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) + kc_entry_finish_invalidating(kc_entry_at_index(i)); + kc_spin_unlock(); + + return res; +} + +/** + * pfk_kc_clear_on_reset() - clear the table and remove all keys from ICE + * The assumption is that at this point we don't have any pending transactions + * Also, there is no need to clear keys from ICE + * + * Return 0 on success, error otherwise + * + */ +void pfk_kc_clear_on_reset(void) +{ + struct kc_entry *entry = NULL; + int i = 0; + + if (!kc_is_ready()) + return; + + kc_spin_lock(); + for (i = 0; i < PFK_KC_TABLE_SIZE; i++) { + entry = kc_entry_at_index(i); + kc_clear_entry(entry); + } + kc_spin_unlock(); +} + +static int pfk_kc_find_storage_type(char **device) +{ + char boot[20] = {'\0'}; + char *match = (char *)strnstr(saved_command_line, + "androidboot.bootdevice=", + strlen(saved_command_line)); + if (match) { + memcpy(boot, (match + strlen("androidboot.bootdevice=")), + sizeof(boot) - 1); + if (strnstr(boot, PFK_UFS, strlen(boot))) + *device = PFK_UFS; + + return 0; + } + return -EINVAL; +} + +static int __init pfk_kc_pre_init(void) +{ + return pfk_kc_find_storage_type(&s_type); +} + +static void __exit pfk_kc_exit(void) +{ + s_type = NULL; +} + +module_init(pfk_kc_pre_init); +module_exit(pfk_kc_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Per-File-Key-KC driver"); |