diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/firmware/efi/vars.c | 1247 |
1 files changed, 1247 insertions, 0 deletions
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c new file mode 100644 index 000000000..e619ced03 --- /dev/null +++ b/drivers/firmware/efi/vars.c @@ -0,0 +1,1247 @@ +/* + * Originally from efivars.c + * + * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com> + * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/capability.h> +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/string.h> +#include <linux/smp.h> +#include <linux/efi.h> +#include <linux/sysfs.h> +#include <linux/device.h> +#include <linux/slab.h> +#include <linux/ctype.h> +#include <linux/ucs2_string.h> + +/* Private pointer to registered efivars */ +static struct efivars *__efivars; + +/* + * efivars_lock protects three things: + * 1) efivarfs_list and efivars_sysfs_list + * 2) ->ops calls + * 3) (un)registration of __efivars + */ +static DEFINE_SEMAPHORE(efivars_lock); + +static bool efivar_wq_enabled = true; +DECLARE_WORK(efivar_work, NULL); +EXPORT_SYMBOL_GPL(efivar_work); + +static bool +validate_device_path(efi_char16_t *var_name, int match, u8 *buffer, + unsigned long len) +{ + struct efi_generic_dev_path *node; + int offset = 0; + + node = (struct efi_generic_dev_path *)buffer; + + if (len < sizeof(*node)) + return false; + + while (offset <= len - sizeof(*node) && + node->length >= sizeof(*node) && + node->length <= len - offset) { + offset += node->length; + + if ((node->type == EFI_DEV_END_PATH || + node->type == EFI_DEV_END_PATH2) && + node->sub_type == EFI_DEV_END_ENTIRE) + return true; + + node = (struct efi_generic_dev_path *)(buffer + offset); + } + + /* + * If we're here then either node->length pointed past the end + * of the buffer or we reached the end of the buffer without + * finding a device path end node. + */ + return false; +} + +static bool +validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer, + unsigned long len) +{ + /* An array of 16-bit integers */ + if ((len % 2) != 0) + return false; + + return true; +} + +static bool +validate_load_option(efi_char16_t *var_name, int match, u8 *buffer, + unsigned long len) +{ + u16 filepathlength; + int i, desclength = 0, namelen; + + namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN); + + /* Either "Boot" or "Driver" followed by four digits of hex */ + for (i = match; i < match+4; i++) { + if (var_name[i] > 127 || + hex_to_bin(var_name[i] & 0xff) < 0) + return true; + } + + /* Reject it if there's 4 digits of hex and then further content */ + if (namelen > match + 4) + return false; + + /* A valid entry must be at least 8 bytes */ + if (len < 8) + return false; + + filepathlength = buffer[4] | buffer[5] << 8; + + /* + * There's no stored length for the description, so it has to be + * found by hand + */ + desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2; + + /* Each boot entry must have a descriptor */ + if (!desclength) + return false; + + /* + * If the sum of the length of the description, the claimed filepath + * length and the original header are greater than the length of the + * variable, it's malformed + */ + if ((desclength + filepathlength + 6) > len) + return false; + + /* + * And, finally, check the filepath + */ + return validate_device_path(var_name, match, buffer + desclength + 6, + filepathlength); +} + +static bool +validate_uint16(efi_char16_t *var_name, int match, u8 *buffer, + unsigned long len) +{ + /* A single 16-bit integer */ + if (len != 2) + return false; + + return true; +} + +static bool +validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer, + unsigned long len) +{ + int i; + + for (i = 0; i < len; i++) { + if (buffer[i] > 127) + return false; + + if (buffer[i] == 0) + return true; + } + + return false; +} + +struct variable_validate { + efi_guid_t vendor; + char *name; + bool (*validate)(efi_char16_t *var_name, int match, u8 *data, + unsigned long len); +}; + +/* + * This is the list of variables we need to validate, as well as the + * whitelist for what we think is safe not to default to immutable. + * + * If it has a validate() method that's not NULL, it'll go into the + * validation routine. If not, it is assumed valid, but still used for + * whitelisting. + * + * Note that it's sorted by {vendor,name}, but globbed names must come after + * any other name with the same prefix. + */ +static const struct variable_validate variable_validate[] = { + { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 }, + { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order }, + { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option }, + { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order }, + { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option }, + { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path }, + { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string }, + { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL }, + { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string }, + { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 }, + { LINUX_EFI_CRASH_GUID, "*", NULL }, + { NULL_GUID, "", NULL }, +}; + +/* + * Check if @var_name matches the pattern given in @match_name. + * + * @var_name: an array of @len non-NUL characters. + * @match_name: a NUL-terminated pattern string, optionally ending in "*". A + * final "*" character matches any trailing characters @var_name, + * including the case when there are none left in @var_name. + * @match: on output, the number of non-wildcard characters in @match_name + * that @var_name matches, regardless of the return value. + * @return: whether @var_name fully matches @match_name. + */ +static bool +variable_matches(const char *var_name, size_t len, const char *match_name, + int *match) +{ + for (*match = 0; ; (*match)++) { + char c = match_name[*match]; + + switch (c) { + case '*': + /* Wildcard in @match_name means we've matched. */ + return true; + + case '\0': + /* @match_name has ended. Has @var_name too? */ + return (*match == len); + + default: + /* + * We've reached a non-wildcard char in @match_name. + * Continue only if there's an identical character in + * @var_name. + */ + if (*match < len && c == var_name[*match]) + continue; + return false; + } + } +} + +bool +efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data, + unsigned long data_size) +{ + int i; + unsigned long utf8_size; + u8 *utf8_name; + + utf8_size = ucs2_utf8size(var_name); + utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL); + if (!utf8_name) + return false; + + ucs2_as_utf8(utf8_name, var_name, utf8_size); + utf8_name[utf8_size] = '\0'; + + for (i = 0; variable_validate[i].name[0] != '\0'; i++) { + const char *name = variable_validate[i].name; + int match = 0; + + if (efi_guidcmp(vendor, variable_validate[i].vendor)) + continue; + + if (variable_matches(utf8_name, utf8_size+1, name, &match)) { + if (variable_validate[i].validate == NULL) + break; + kfree(utf8_name); + return variable_validate[i].validate(var_name, match, + data, data_size); + } + } + kfree(utf8_name); + return true; +} +EXPORT_SYMBOL_GPL(efivar_validate); + +bool +efivar_variable_is_removable(efi_guid_t vendor, const char *var_name, + size_t len) +{ + int i; + bool found = false; + int match = 0; + + /* + * Check if our variable is in the validated variables list + */ + for (i = 0; variable_validate[i].name[0] != '\0'; i++) { + if (efi_guidcmp(variable_validate[i].vendor, vendor)) + continue; + + if (variable_matches(var_name, len, + variable_validate[i].name, &match)) { + found = true; + break; + } + } + + /* + * If it's in our list, it is removable. + */ + return found; +} +EXPORT_SYMBOL_GPL(efivar_variable_is_removable); + +static efi_status_t +check_var_size(u32 attributes, unsigned long size) +{ + const struct efivar_operations *fops; + + if (!__efivars) + return EFI_UNSUPPORTED; + + fops = __efivars->ops; + + if (!fops->query_variable_store) + return EFI_UNSUPPORTED; + + return fops->query_variable_store(attributes, size, false); +} + +static efi_status_t +check_var_size_nonblocking(u32 attributes, unsigned long size) +{ + const struct efivar_operations *fops; + + if (!__efivars) + return EFI_UNSUPPORTED; + + fops = __efivars->ops; + + if (!fops->query_variable_store) + return EFI_UNSUPPORTED; + + return fops->query_variable_store(attributes, size, true); +} + +static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor, + struct list_head *head) +{ + struct efivar_entry *entry, *n; + unsigned long strsize1, strsize2; + bool found = false; + + strsize1 = ucs2_strsize(variable_name, 1024); + list_for_each_entry_safe(entry, n, head, list) { + strsize2 = ucs2_strsize(entry->var.VariableName, 1024); + if (strsize1 == strsize2 && + !memcmp(variable_name, &(entry->var.VariableName), + strsize2) && + !efi_guidcmp(entry->var.VendorGuid, + *vendor)) { + found = true; + break; + } + } + return found; +} + +/* + * Returns the size of variable_name, in bytes, including the + * terminating NULL character, or variable_name_size if no NULL + * character is found among the first variable_name_size bytes. + */ +static unsigned long var_name_strnsize(efi_char16_t *variable_name, + unsigned long variable_name_size) +{ + unsigned long len; + efi_char16_t c; + + /* + * The variable name is, by definition, a NULL-terminated + * string, so make absolutely sure that variable_name_size is + * the value we expect it to be. If not, return the real size. + */ + for (len = 2; len <= variable_name_size; len += sizeof(c)) { + c = variable_name[(len / sizeof(c)) - 1]; + if (!c) + break; + } + + return min(len, variable_name_size); +} + +/* + * Print a warning when duplicate EFI variables are encountered and + * disable the sysfs workqueue since the firmware is buggy. + */ +static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid, + unsigned long len16) +{ + size_t i, len8 = len16 / sizeof(efi_char16_t); + char *str8; + + /* + * Disable the workqueue since the algorithm it uses for + * detecting new variables won't work with this buggy + * implementation of GetNextVariableName(). + */ + efivar_wq_enabled = false; + + str8 = kzalloc(len8, GFP_KERNEL); + if (!str8) + return; + + for (i = 0; i < len8; i++) + str8[i] = str16[i]; + + printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n", + str8, vendor_guid); + kfree(str8); +} + +/** + * efivar_init - build the initial list of EFI variables + * @func: callback function to invoke for every variable + * @data: function-specific data to pass to @func + * @atomic: do we need to execute the @func-loop atomically? + * @duplicates: error if we encounter duplicates on @head? + * @head: initialised head of variable list + * + * Get every EFI variable from the firmware and invoke @func. @func + * should call efivar_entry_add() to build the list of variables. + * + * Returns 0 on success, or a kernel error code on failure. + */ +int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), + void *data, bool duplicates, struct list_head *head) +{ + const struct efivar_operations *ops; + unsigned long variable_name_size = 1024; + efi_char16_t *variable_name; + efi_status_t status; + efi_guid_t vendor_guid; + int err = 0; + + if (!__efivars) + return -EFAULT; + + ops = __efivars->ops; + + variable_name = kzalloc(variable_name_size, GFP_KERNEL); + if (!variable_name) { + printk(KERN_ERR "efivars: Memory allocation failed.\n"); + return -ENOMEM; + } + + if (down_interruptible(&efivars_lock)) { + err = -EINTR; + goto free; + } + + /* + * Per EFI spec, the maximum storage allocated for both + * the variable name and variable data is 1024 bytes. + */ + + do { + variable_name_size = 1024; + + status = ops->get_next_variable(&variable_name_size, + variable_name, + &vendor_guid); + switch (status) { + case EFI_SUCCESS: + if (duplicates) + up(&efivars_lock); + + variable_name_size = var_name_strnsize(variable_name, + variable_name_size); + + /* + * Some firmware implementations return the + * same variable name on multiple calls to + * get_next_variable(). Terminate the loop + * immediately as there is no guarantee that + * we'll ever see a different variable name, + * and may end up looping here forever. + */ + if (duplicates && + variable_is_present(variable_name, &vendor_guid, + head)) { + dup_variable_bug(variable_name, &vendor_guid, + variable_name_size); + status = EFI_NOT_FOUND; + } else { + err = func(variable_name, vendor_guid, + variable_name_size, data); + if (err) + status = EFI_NOT_FOUND; + } + + if (duplicates) { + if (down_interruptible(&efivars_lock)) { + err = -EINTR; + goto free; + } + } + + break; + case EFI_NOT_FOUND: + break; + default: + printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n", + status); + status = EFI_NOT_FOUND; + break; + } + + } while (status != EFI_NOT_FOUND); + + up(&efivars_lock); +free: + kfree(variable_name); + + return err; +} +EXPORT_SYMBOL_GPL(efivar_init); + +/** + * efivar_entry_add - add entry to variable list + * @entry: entry to add to list + * @head: list head + * + * Returns 0 on success, or a kernel error code on failure. + */ +int efivar_entry_add(struct efivar_entry *entry, struct list_head *head) +{ + if (down_interruptible(&efivars_lock)) + return -EINTR; + list_add(&entry->list, head); + up(&efivars_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(efivar_entry_add); + +/** + * efivar_entry_remove - remove entry from variable list + * @entry: entry to remove from list + * + * Returns 0 on success, or a kernel error code on failure. + */ +int efivar_entry_remove(struct efivar_entry *entry) +{ + if (down_interruptible(&efivars_lock)) + return -EINTR; + list_del(&entry->list); + up(&efivars_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(efivar_entry_remove); + +/* + * efivar_entry_list_del_unlock - remove entry from variable list + * @entry: entry to remove + * + * Remove @entry from the variable list and release the list lock. + * + * NOTE: slightly weird locking semantics here - we expect to be + * called with the efivars lock already held, and we release it before + * returning. This is because this function is usually called after + * set_variable() while the lock is still held. + */ +static void efivar_entry_list_del_unlock(struct efivar_entry *entry) +{ + list_del(&entry->list); + up(&efivars_lock); +} + +/** + * __efivar_entry_delete - delete an EFI variable + * @entry: entry containing EFI variable to delete + * + * Delete the variable from the firmware but leave @entry on the + * variable list. + * + * This function differs from efivar_entry_delete() because it does + * not remove @entry from the variable list. Also, it is safe to be + * called from within a efivar_entry_iter_begin() and + * efivar_entry_iter_end() region, unlike efivar_entry_delete(). + * + * Returns 0 on success, or a converted EFI status code if + * set_variable() fails. + */ +int __efivar_entry_delete(struct efivar_entry *entry) +{ + efi_status_t status; + + if (!__efivars) + return -EINVAL; + + status = __efivars->ops->set_variable(entry->var.VariableName, + &entry->var.VendorGuid, + 0, 0, NULL); + + return efi_status_to_err(status); +} +EXPORT_SYMBOL_GPL(__efivar_entry_delete); + +/** + * efivar_entry_delete - delete variable and remove entry from list + * @entry: entry containing variable to delete + * + * Delete the variable from the firmware and remove @entry from the + * variable list. It is the caller's responsibility to free @entry + * once we return. + * + * Returns 0 on success, -EINTR if we can't grab the semaphore, + * converted EFI status code if set_variable() fails. + */ +int efivar_entry_delete(struct efivar_entry *entry) +{ + const struct efivar_operations *ops; + efi_status_t status; + + if (down_interruptible(&efivars_lock)) + return -EINTR; + + if (!__efivars) { + up(&efivars_lock); + return -EINVAL; + } + ops = __efivars->ops; + status = ops->set_variable(entry->var.VariableName, + &entry->var.VendorGuid, + 0, 0, NULL); + if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) { + up(&efivars_lock); + return efi_status_to_err(status); + } + + efivar_entry_list_del_unlock(entry); + return 0; +} +EXPORT_SYMBOL_GPL(efivar_entry_delete); + +/** + * efivar_entry_set - call set_variable() + * @entry: entry containing the EFI variable to write + * @attributes: variable attributes + * @size: size of @data buffer + * @data: buffer containing variable data + * @head: head of variable list + * + * Calls set_variable() for an EFI variable. If creating a new EFI + * variable, this function is usually followed by efivar_entry_add(). + * + * Before writing the variable, the remaining EFI variable storage + * space is checked to ensure there is enough room available. + * + * If @head is not NULL a lookup is performed to determine whether + * the entry is already on the list. + * + * Returns 0 on success, -EINTR if we can't grab the semaphore, + * -EEXIST if a lookup is performed and the entry already exists on + * the list, or a converted EFI status code if set_variable() fails. + */ +int efivar_entry_set(struct efivar_entry *entry, u32 attributes, + unsigned long size, void *data, struct list_head *head) +{ + const struct efivar_operations *ops; + efi_status_t status; + efi_char16_t *name = entry->var.VariableName; + efi_guid_t vendor = entry->var.VendorGuid; + + if (down_interruptible(&efivars_lock)) + return -EINTR; + + if (!__efivars) { + up(&efivars_lock); + return -EINVAL; + } + ops = __efivars->ops; + if (head && efivar_entry_find(name, vendor, head, false)) { + up(&efivars_lock); + return -EEXIST; + } + + status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); + if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED) + status = ops->set_variable(name, &vendor, + attributes, size, data); + + up(&efivars_lock); + + return efi_status_to_err(status); + +} +EXPORT_SYMBOL_GPL(efivar_entry_set); + +/* + * efivar_entry_set_nonblocking - call set_variable_nonblocking() + * + * This function is guaranteed to not block and is suitable for calling + * from crash/panic handlers. + * + * Crucially, this function will not block if it cannot acquire + * efivars_lock. Instead, it returns -EBUSY. + */ +static int +efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, + u32 attributes, unsigned long size, void *data) +{ + const struct efivar_operations *ops; + efi_status_t status; + + if (down_trylock(&efivars_lock)) + return -EBUSY; + + if (!__efivars) { + up(&efivars_lock); + return -EINVAL; + } + + status = check_var_size_nonblocking(attributes, + size + ucs2_strsize(name, 1024)); + if (status != EFI_SUCCESS) { + up(&efivars_lock); + return -ENOSPC; + } + + ops = __efivars->ops; + status = ops->set_variable_nonblocking(name, &vendor, attributes, + size, data); + + up(&efivars_lock); + return efi_status_to_err(status); +} + +/** + * efivar_entry_set_safe - call set_variable() if enough space in firmware + * @name: buffer containing the variable name + * @vendor: variable vendor guid + * @attributes: variable attributes + * @block: can we block in this context? + * @size: size of @data buffer + * @data: buffer containing variable data + * + * Ensures there is enough free storage in the firmware for this variable, and + * if so, calls set_variable(). If creating a new EFI variable, this function + * is usually followed by efivar_entry_add(). + * + * Returns 0 on success, -ENOSPC if the firmware does not have enough + * space for set_variable() to succeed, or a converted EFI status code + * if set_variable() fails. + */ +int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes, + bool block, unsigned long size, void *data) +{ + const struct efivar_operations *ops; + efi_status_t status; + unsigned long varsize; + + if (!__efivars) + return -EINVAL; + + ops = __efivars->ops; + if (!ops->query_variable_store) + return -ENOSYS; + + /* + * If the EFI variable backend provides a non-blocking + * ->set_variable() operation and we're in a context where we + * cannot block, then we need to use it to avoid live-locks, + * since the implication is that the regular ->set_variable() + * will block. + * + * If no ->set_variable_nonblocking() is provided then + * ->set_variable() is assumed to be non-blocking. + */ + if (!block && ops->set_variable_nonblocking) + return efivar_entry_set_nonblocking(name, vendor, attributes, + size, data); + + varsize = size + ucs2_strsize(name, 1024); + if (!block) { + if (down_trylock(&efivars_lock)) + return -EBUSY; + status = check_var_size_nonblocking(attributes, varsize); + } else { + if (down_interruptible(&efivars_lock)) + return -EINTR; + status = check_var_size(attributes, varsize); + } + + if (status != EFI_SUCCESS) { + up(&efivars_lock); + return -ENOSPC; + } + + status = ops->set_variable(name, &vendor, attributes, size, data); + + up(&efivars_lock); + + return efi_status_to_err(status); +} +EXPORT_SYMBOL_GPL(efivar_entry_set_safe); + +/** + * efivar_entry_find - search for an entry + * @name: the EFI variable name + * @guid: the EFI variable vendor's guid + * @head: head of the variable list + * @remove: should we remove the entry from the list? + * + * Search for an entry on the variable list that has the EFI variable + * name @name and vendor guid @guid. If an entry is found on the list + * and @remove is true, the entry is removed from the list. + * + * The caller MUST call efivar_entry_iter_begin() and + * efivar_entry_iter_end() before and after the invocation of this + * function, respectively. + * + * Returns the entry if found on the list, %NULL otherwise. + */ +struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid, + struct list_head *head, bool remove) +{ + struct efivar_entry *entry, *n; + int strsize1, strsize2; + bool found = false; + + list_for_each_entry_safe(entry, n, head, list) { + strsize1 = ucs2_strsize(name, 1024); + strsize2 = ucs2_strsize(entry->var.VariableName, 1024); + if (strsize1 == strsize2 && + !memcmp(name, &(entry->var.VariableName), strsize1) && + !efi_guidcmp(guid, entry->var.VendorGuid)) { + found = true; + break; + } + } + + if (!found) + return NULL; + + if (remove) { + if (entry->scanning) { + /* + * The entry will be deleted + * after scanning is completed. + */ + entry->deleting = true; + } else + list_del(&entry->list); + } + + return entry; +} +EXPORT_SYMBOL_GPL(efivar_entry_find); + +/** + * efivar_entry_size - obtain the size of a variable + * @entry: entry for this variable + * @size: location to store the variable's size + */ +int efivar_entry_size(struct efivar_entry *entry, unsigned long *size) +{ + const struct efivar_operations *ops; + efi_status_t status; + + *size = 0; + + if (down_interruptible(&efivars_lock)) + return -EINTR; + if (!__efivars) { + up(&efivars_lock); + return -EINVAL; + } + ops = __efivars->ops; + status = ops->get_variable(entry->var.VariableName, + &entry->var.VendorGuid, NULL, size, NULL); + up(&efivars_lock); + + if (status != EFI_BUFFER_TOO_SMALL) + return efi_status_to_err(status); + + return 0; +} +EXPORT_SYMBOL_GPL(efivar_entry_size); + +/** + * __efivar_entry_get - call get_variable() + * @entry: read data for this variable + * @attributes: variable attributes + * @size: size of @data buffer + * @data: buffer to store variable data + * + * The caller MUST call efivar_entry_iter_begin() and + * efivar_entry_iter_end() before and after the invocation of this + * function, respectively. + */ +int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes, + unsigned long *size, void *data) +{ + efi_status_t status; + + if (!__efivars) + return -EINVAL; + + status = __efivars->ops->get_variable(entry->var.VariableName, + &entry->var.VendorGuid, + attributes, size, data); + + return efi_status_to_err(status); +} +EXPORT_SYMBOL_GPL(__efivar_entry_get); + +/** + * efivar_entry_get - call get_variable() + * @entry: read data for this variable + * @attributes: variable attributes + * @size: size of @data buffer + * @data: buffer to store variable data + */ +int efivar_entry_get(struct efivar_entry *entry, u32 *attributes, + unsigned long *size, void *data) +{ + efi_status_t status; + + if (down_interruptible(&efivars_lock)) + return -EINTR; + + if (!__efivars) { + up(&efivars_lock); + return -EINVAL; + } + + status = __efivars->ops->get_variable(entry->var.VariableName, + &entry->var.VendorGuid, + attributes, size, data); + up(&efivars_lock); + + return efi_status_to_err(status); +} +EXPORT_SYMBOL_GPL(efivar_entry_get); + +/** + * efivar_entry_set_get_size - call set_variable() and get new size (atomic) + * @entry: entry containing variable to set and get + * @attributes: attributes of variable to be written + * @size: size of data buffer + * @data: buffer containing data to write + * @set: did the set_variable() call succeed? + * + * This is a pretty special (complex) function. See efivarfs_file_write(). + * + * Atomically call set_variable() for @entry and if the call is + * successful, return the new size of the variable from get_variable() + * in @size. The success of set_variable() is indicated by @set. + * + * Returns 0 on success, -EINVAL if the variable data is invalid, + * -ENOSPC if the firmware does not have enough available space, or a + * converted EFI status code if either of set_variable() or + * get_variable() fail. + * + * If the EFI variable does not exist when calling set_variable() + * (EFI_NOT_FOUND), @entry is removed from the variable list. + */ +int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes, + unsigned long *size, void *data, bool *set) +{ + const struct efivar_operations *ops; + efi_char16_t *name = entry->var.VariableName; + efi_guid_t *vendor = &entry->var.VendorGuid; + efi_status_t status; + int err; + + *set = false; + + if (efivar_validate(*vendor, name, data, *size) == false) + return -EINVAL; + + /* + * The lock here protects the get_variable call, the conditional + * set_variable call, and removal of the variable from the efivars + * list (in the case of an authenticated delete). + */ + if (down_interruptible(&efivars_lock)) + return -EINTR; + + if (!__efivars) { + err = -EINVAL; + goto out; + } + + /* + * Ensure that the available space hasn't shrunk below the safe level + */ + status = check_var_size(attributes, *size + ucs2_strsize(name, 1024)); + if (status != EFI_SUCCESS) { + if (status != EFI_UNSUPPORTED) { + err = efi_status_to_err(status); + goto out; + } + + if (*size > 65536) { + err = -ENOSPC; + goto out; + } + } + + ops = __efivars->ops; + + status = ops->set_variable(name, vendor, attributes, *size, data); + if (status != EFI_SUCCESS) { + err = efi_status_to_err(status); + goto out; + } + + *set = true; + + /* + * Writing to the variable may have caused a change in size (which + * could either be an append or an overwrite), or the variable to be + * deleted. Perform a GetVariable() so we can tell what actually + * happened. + */ + *size = 0; + status = ops->get_variable(entry->var.VariableName, + &entry->var.VendorGuid, + NULL, size, NULL); + + if (status == EFI_NOT_FOUND) + efivar_entry_list_del_unlock(entry); + else + up(&efivars_lock); + + if (status && status != EFI_BUFFER_TOO_SMALL) + return efi_status_to_err(status); + + return 0; + +out: + up(&efivars_lock); + return err; + +} +EXPORT_SYMBOL_GPL(efivar_entry_set_get_size); + +/** + * efivar_entry_iter_begin - begin iterating the variable list + * + * Lock the variable list to prevent entry insertion and removal until + * efivar_entry_iter_end() is called. This function is usually used in + * conjunction with __efivar_entry_iter() or efivar_entry_iter(). + */ +int efivar_entry_iter_begin(void) +{ + return down_interruptible(&efivars_lock); +} +EXPORT_SYMBOL_GPL(efivar_entry_iter_begin); + +/** + * efivar_entry_iter_end - finish iterating the variable list + * + * Unlock the variable list and allow modifications to the list again. + */ +void efivar_entry_iter_end(void) +{ + up(&efivars_lock); +} +EXPORT_SYMBOL_GPL(efivar_entry_iter_end); + +/** + * __efivar_entry_iter - iterate over variable list + * @func: callback function + * @head: head of the variable list + * @data: function-specific data to pass to callback + * @prev: entry to begin iterating from + * + * Iterate over the list of EFI variables and call @func with every + * entry on the list. It is safe for @func to remove entries in the + * list via efivar_entry_delete(). + * + * You MUST call efivar_enter_iter_begin() before this function, and + * efivar_entry_iter_end() afterwards. + * + * It is possible to begin iteration from an arbitrary entry within + * the list by passing @prev. @prev is updated on return to point to + * the last entry passed to @func. To begin iterating from the + * beginning of the list @prev must be %NULL. + * + * The restrictions for @func are the same as documented for + * efivar_entry_iter(). + */ +int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *), + struct list_head *head, void *data, + struct efivar_entry **prev) +{ + struct efivar_entry *entry, *n; + int err = 0; + + if (!prev || !*prev) { + list_for_each_entry_safe(entry, n, head, list) { + err = func(entry, data); + if (err) + break; + } + + if (prev) + *prev = entry; + + return err; + } + + + list_for_each_entry_safe_continue((*prev), n, head, list) { + err = func(*prev, data); + if (err) + break; + } + + return err; +} +EXPORT_SYMBOL_GPL(__efivar_entry_iter); + +/** + * efivar_entry_iter - iterate over variable list + * @func: callback function + * @head: head of variable list + * @data: function-specific data to pass to callback + * + * Iterate over the list of EFI variables and call @func with every + * entry on the list. It is safe for @func to remove entries in the + * list via efivar_entry_delete() while iterating. + * + * Some notes for the callback function: + * - a non-zero return value indicates an error and terminates the loop + * - @func is called from atomic context + */ +int efivar_entry_iter(int (*func)(struct efivar_entry *, void *), + struct list_head *head, void *data) +{ + int err = 0; + + err = efivar_entry_iter_begin(); + if (err) + return err; + err = __efivar_entry_iter(func, head, data, NULL); + efivar_entry_iter_end(); + + return err; +} +EXPORT_SYMBOL_GPL(efivar_entry_iter); + +/** + * efivars_kobject - get the kobject for the registered efivars + * + * If efivars_register() has not been called we return NULL, + * otherwise return the kobject used at registration time. + */ +struct kobject *efivars_kobject(void) +{ + if (!__efivars) + return NULL; + + return __efivars->kobject; +} +EXPORT_SYMBOL_GPL(efivars_kobject); + +/** + * efivar_run_worker - schedule the efivar worker thread + */ +void efivar_run_worker(void) +{ + if (efivar_wq_enabled) + schedule_work(&efivar_work); +} +EXPORT_SYMBOL_GPL(efivar_run_worker); + +/** + * efivars_register - register an efivars + * @efivars: efivars to register + * @ops: efivars operations + * @kobject: @efivars-specific kobject + * + * Only a single efivars can be registered at any time. + */ +int efivars_register(struct efivars *efivars, + const struct efivar_operations *ops, + struct kobject *kobject) +{ + if (down_interruptible(&efivars_lock)) + return -EINTR; + + efivars->ops = ops; + efivars->kobject = kobject; + + __efivars = efivars; + + pr_info("Registered efivars operations\n"); + + up(&efivars_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(efivars_register); + +/** + * efivars_unregister - unregister an efivars + * @efivars: efivars to unregister + * + * The caller must have already removed every entry from the list, + * failure to do so is an error. + */ +int efivars_unregister(struct efivars *efivars) +{ + int rv; + + if (down_interruptible(&efivars_lock)) + return -EINTR; + + if (!__efivars) { + printk(KERN_ERR "efivars not registered\n"); + rv = -EINVAL; + goto out; + } + + if (__efivars != efivars) { + rv = -EINVAL; + goto out; + } + + pr_info("Unregistered efivars operations\n"); + __efivars = NULL; + + rv = 0; +out: + up(&efivars_lock); + return rv; +} +EXPORT_SYMBOL_GPL(efivars_unregister); |