diff options
Diffstat (limited to 'fs/efivarfs')
| -rw-r--r-- | fs/efivarfs/Kconfig | 14 | ||||
| -rw-r--r-- | fs/efivarfs/Makefile | 8 | ||||
| -rw-r--r-- | fs/efivarfs/file.c | 114 | ||||
| -rw-r--r-- | fs/efivarfs/inode.c | 184 | ||||
| -rw-r--r-- | fs/efivarfs/internal.h | 60 | ||||
| -rw-r--r-- | fs/efivarfs/super.c | 288 | ||||
| -rw-r--r-- | fs/efivarfs/vars.c | 722 |
7 files changed, 1390 insertions, 0 deletions
diff --git a/fs/efivarfs/Kconfig b/fs/efivarfs/Kconfig new file mode 100644 index 000000000..edec8a19c --- /dev/null +++ b/fs/efivarfs/Kconfig @@ -0,0 +1,14 @@ +# SPDX-License-Identifier: GPL-2.0-only +config EFIVAR_FS + tristate "EFI Variable filesystem" + depends on EFI + default m + help + efivarfs is a replacement filesystem for the old EFI + variable support via sysfs, as it doesn't suffer from the + same 1024-byte variable size limit. + + To compile this file system support as a module, choose M + here. The module will be called efivarfs. + + If unsure, say N. diff --git a/fs/efivarfs/Makefile b/fs/efivarfs/Makefile new file mode 100644 index 000000000..7bfc2f975 --- /dev/null +++ b/fs/efivarfs/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Makefile for the efivarfs filesystem +# + +obj-$(CONFIG_EFIVAR_FS) += efivarfs.o + +efivarfs-objs := inode.o file.o super.o vars.o diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c new file mode 100644 index 000000000..d57ee1587 --- /dev/null +++ b/fs/efivarfs/file.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat, Inc. + * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> + */ + +#include <linux/efi.h> +#include <linux/delay.h> +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/mount.h> + +#include "internal.h" + +static ssize_t efivarfs_file_write(struct file *file, + const char __user *userbuf, size_t count, loff_t *ppos) +{ + struct efivar_entry *var = file->private_data; + void *data; + u32 attributes; + struct inode *inode = file->f_mapping->host; + unsigned long datasize = count - sizeof(attributes); + ssize_t bytes; + bool set = false; + + if (count < sizeof(attributes)) + return -EINVAL; + + if (copy_from_user(&attributes, userbuf, sizeof(attributes))) + return -EFAULT; + + if (attributes & ~(EFI_VARIABLE_MASK)) + return -EINVAL; + + data = memdup_user(userbuf + sizeof(attributes), datasize); + if (IS_ERR(data)) + return PTR_ERR(data); + + bytes = efivar_entry_set_get_size(var, attributes, &datasize, + data, &set); + if (!set && bytes) { + if (bytes == -ENOENT) + bytes = -EIO; + goto out; + } + + if (bytes == -ENOENT) { + drop_nlink(inode); + d_delete(file->f_path.dentry); + dput(file->f_path.dentry); + } else { + inode_lock(inode); + i_size_write(inode, datasize + sizeof(attributes)); + inode->i_mtime = current_time(inode); + inode_unlock(inode); + } + + bytes = count; + +out: + kfree(data); + + return bytes; +} + +static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, + size_t count, loff_t *ppos) +{ + struct efivar_entry *var = file->private_data; + unsigned long datasize = 0; + u32 attributes; + void *data; + ssize_t size = 0; + int err; + + while (!__ratelimit(&file->f_cred->user->ratelimit)) + msleep(50); + + err = efivar_entry_size(var, &datasize); + + /* + * efivarfs represents uncommitted variables with + * zero-length files. Reading them should return EOF. + */ + if (err == -ENOENT) + return 0; + else if (err) + return err; + + data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); + + if (!data) + return -ENOMEM; + + size = efivar_entry_get(var, &attributes, &datasize, + data + sizeof(attributes)); + if (size) + goto out_free; + + memcpy(data, &attributes, sizeof(attributes)); + size = simple_read_from_buffer(userbuf, count, ppos, + data, datasize + sizeof(attributes)); +out_free: + kfree(data); + + return size; +} + +const struct file_operations efivarfs_file_operations = { + .open = simple_open, + .read = efivarfs_file_read, + .write = efivarfs_file_write, + .llseek = no_llseek, +}; diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c new file mode 100644 index 000000000..939e5e242 --- /dev/null +++ b/fs/efivarfs/inode.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat, Inc. + * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> + */ + +#include <linux/efi.h> +#include <linux/fs.h> +#include <linux/ctype.h> +#include <linux/kmemleak.h> +#include <linux/slab.h> +#include <linux/uuid.h> +#include <linux/fileattr.h> + +#include "internal.h" + +static const struct inode_operations efivarfs_file_inode_operations; + +struct inode *efivarfs_get_inode(struct super_block *sb, + const struct inode *dir, int mode, + dev_t dev, bool is_removable) +{ + struct inode *inode = new_inode(sb); + + if (inode) { + inode->i_ino = get_next_ino(); + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + inode->i_flags = is_removable ? 0 : S_IMMUTABLE; + switch (mode & S_IFMT) { + case S_IFREG: + inode->i_op = &efivarfs_file_inode_operations; + inode->i_fop = &efivarfs_file_operations; + break; + case S_IFDIR: + inode->i_op = &efivarfs_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + inc_nlink(inode); + break; + } + } + return inode; +} + +/* + * Return true if 'str' is a valid efivarfs filename of the form, + * + * VariableName-12345678-1234-1234-1234-1234567891bc + */ +bool efivarfs_valid_name(const char *str, int len) +{ + const char *s = str + len - EFI_VARIABLE_GUID_LEN; + + /* + * We need a GUID, plus at least one letter for the variable name, + * plus the '-' separator + */ + if (len < EFI_VARIABLE_GUID_LEN + 2) + return false; + + /* GUID must be preceded by a '-' */ + if (*(s - 1) != '-') + return false; + + /* + * Validate that 's' is of the correct format, e.g. + * + * 12345678-1234-1234-1234-123456789abc + */ + return uuid_is_valid(s); +} + +static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) +{ + struct inode *inode = NULL; + struct efivar_entry *var; + int namelen, i = 0, err = 0; + bool is_removable = false; + + if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) + return -EINVAL; + + var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); + if (!var) + return -ENOMEM; + + /* length of the variable name itself: remove GUID and separator */ + namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; + + err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); + if (err) + goto out; + + if (efivar_variable_is_removable(var->var.VendorGuid, + dentry->d_name.name, namelen)) + is_removable = true; + + inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable); + if (!inode) { + err = -ENOMEM; + goto out; + } + + for (i = 0; i < namelen; i++) + var->var.VariableName[i] = dentry->d_name.name[i]; + + var->var.VariableName[i] = '\0'; + + inode->i_private = var; + kmemleak_ignore(var); + + err = efivar_entry_add(var, &efivarfs_list); + if (err) + goto out; + + d_instantiate(dentry, inode); + dget(dentry); +out: + if (err) { + kfree(var); + if (inode) + iput(inode); + } + return err; +} + +static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) +{ + struct efivar_entry *var = d_inode(dentry)->i_private; + + if (efivar_entry_delete(var)) + return -EINVAL; + + drop_nlink(d_inode(dentry)); + dput(dentry); + return 0; +}; + +const struct inode_operations efivarfs_dir_inode_operations = { + .lookup = simple_lookup, + .unlink = efivarfs_unlink, + .create = efivarfs_create, +}; + +static int +efivarfs_fileattr_get(struct dentry *dentry, struct fileattr *fa) +{ + unsigned int i_flags; + unsigned int flags = 0; + + i_flags = d_inode(dentry)->i_flags; + if (i_flags & S_IMMUTABLE) + flags |= FS_IMMUTABLE_FL; + + fileattr_fill_flags(fa, flags); + + return 0; +} + +static int +efivarfs_fileattr_set(struct user_namespace *mnt_userns, + struct dentry *dentry, struct fileattr *fa) +{ + unsigned int i_flags = 0; + + if (fileattr_has_fsx(fa)) + return -EOPNOTSUPP; + + if (fa->flags & ~FS_IMMUTABLE_FL) + return -EOPNOTSUPP; + + if (fa->flags & FS_IMMUTABLE_FL) + i_flags |= S_IMMUTABLE; + + inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE); + + return 0; +} + +static const struct inode_operations efivarfs_file_inode_operations = { + .fileattr_get = efivarfs_fileattr_get, + .fileattr_set = efivarfs_fileattr_set, +}; diff --git a/fs/efivarfs/internal.h b/fs/efivarfs/internal.h new file mode 100644 index 000000000..8ebf3a6a8 --- /dev/null +++ b/fs/efivarfs/internal.h @@ -0,0 +1,60 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2012 Red Hat, Inc. + * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> + */ +#ifndef EFIVAR_FS_INTERNAL_H +#define EFIVAR_FS_INTERNAL_H + +#include <linux/list.h> +#include <linux/efi.h> + +struct efi_variable { + efi_char16_t VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)]; + efi_guid_t VendorGuid; + unsigned long DataSize; + __u8 Data[1024]; + efi_status_t Status; + __u32 Attributes; +} __attribute__((packed)); + +struct efivar_entry { + struct efi_variable var; + struct list_head list; + struct kobject kobj; +}; + +int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), + void *data, bool duplicates, struct list_head *head); + +int efivar_entry_add(struct efivar_entry *entry, struct list_head *head); +void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head); +void efivar_entry_remove(struct efivar_entry *entry); +int efivar_entry_delete(struct efivar_entry *entry); + +int efivar_entry_size(struct efivar_entry *entry, unsigned long *size); +int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes, + unsigned long *size, void *data); +int efivar_entry_get(struct efivar_entry *entry, u32 *attributes, + unsigned long *size, void *data); +int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes, + unsigned long *size, void *data, bool *set); + +int efivar_entry_iter(int (*func)(struct efivar_entry *, void *), + struct list_head *head, void *data); + +bool efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data, + unsigned long data_size); +bool efivar_variable_is_removable(efi_guid_t vendor, const char *name, + size_t len); + +extern const struct file_operations efivarfs_file_operations; +extern const struct inode_operations efivarfs_dir_inode_operations; +extern bool efivarfs_valid_name(const char *str, int len); +extern struct inode *efivarfs_get_inode(struct super_block *sb, + const struct inode *dir, int mode, dev_t dev, + bool is_removable); + +extern struct list_head efivarfs_list; + +#endif /* EFIVAR_FS_INTERNAL_H */ diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c new file mode 100644 index 000000000..77c7615bb --- /dev/null +++ b/fs/efivarfs/super.c @@ -0,0 +1,288 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Red Hat, Inc. + * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> + */ + +#include <linux/ctype.h> +#include <linux/efi.h> +#include <linux/fs.h> +#include <linux/fs_context.h> +#include <linux/module.h> +#include <linux/pagemap.h> +#include <linux/ucs2_string.h> +#include <linux/slab.h> +#include <linux/magic.h> +#include <linux/printk.h> + +#include "internal.h" + +LIST_HEAD(efivarfs_list); + +static void efivarfs_evict_inode(struct inode *inode) +{ + clear_inode(inode); +} + +static const struct super_operations efivarfs_ops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, + .evict_inode = efivarfs_evict_inode, +}; + +/* + * Compare two efivarfs file names. + * + * An efivarfs filename is composed of two parts, + * + * 1. A case-sensitive variable name + * 2. A case-insensitive GUID + * + * So we need to perform a case-sensitive match on part 1 and a + * case-insensitive match on part 2. + */ +static int efivarfs_d_compare(const struct dentry *dentry, + unsigned int len, const char *str, + const struct qstr *name) +{ + int guid = len - EFI_VARIABLE_GUID_LEN; + + if (name->len != len) + return 1; + + /* Case-sensitive compare for the variable name */ + if (memcmp(str, name->name, guid)) + return 1; + + /* Case-insensitive compare for the GUID */ + return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); +} + +static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) +{ + unsigned long hash = init_name_hash(dentry); + const unsigned char *s = qstr->name; + unsigned int len = qstr->len; + + if (!efivarfs_valid_name(s, len)) + return -EINVAL; + + while (len-- > EFI_VARIABLE_GUID_LEN) + hash = partial_name_hash(*s++, hash); + + /* GUID is case-insensitive. */ + while (len--) + hash = partial_name_hash(tolower(*s++), hash); + + qstr->hash = end_name_hash(hash); + return 0; +} + +static const struct dentry_operations efivarfs_d_ops = { + .d_compare = efivarfs_d_compare, + .d_hash = efivarfs_d_hash, + .d_delete = always_delete_dentry, +}; + +static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) +{ + struct dentry *d; + struct qstr q; + int err; + + q.name = name; + q.len = strlen(name); + + err = efivarfs_d_hash(parent, &q); + if (err) + return ERR_PTR(err); + + d = d_alloc(parent, &q); + if (d) + return d; + + return ERR_PTR(-ENOMEM); +} + +static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, + unsigned long name_size, void *data) +{ + struct super_block *sb = (struct super_block *)data; + struct efivar_entry *entry; + struct inode *inode = NULL; + struct dentry *dentry, *root = sb->s_root; + unsigned long size = 0; + char *name; + int len; + int err = -ENOMEM; + bool is_removable = false; + + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + return err; + + memcpy(entry->var.VariableName, name16, name_size); + memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); + + len = ucs2_utf8size(entry->var.VariableName); + + /* name, plus '-', plus GUID, plus NUL*/ + name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); + if (!name) + goto fail; + + ucs2_as_utf8(name, entry->var.VariableName, len); + + if (efivar_variable_is_removable(entry->var.VendorGuid, name, len)) + is_removable = true; + + name[len] = '-'; + + efi_guid_to_str(&entry->var.VendorGuid, name + len + 1); + + name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; + + /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */ + strreplace(name, '/', '!'); + + inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, + is_removable); + if (!inode) + goto fail_name; + + dentry = efivarfs_alloc_dentry(root, name); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); + goto fail_inode; + } + + __efivar_entry_get(entry, NULL, &size, NULL); + __efivar_entry_add(entry, &efivarfs_list); + + /* copied by the above to local storage in the dentry. */ + kfree(name); + + inode_lock(inode); + inode->i_private = entry; + i_size_write(inode, size + sizeof(entry->var.Attributes)); + inode_unlock(inode); + d_add(dentry, inode); + + return 0; + +fail_inode: + iput(inode); +fail_name: + kfree(name); +fail: + kfree(entry); + return err; +} + +static int efivarfs_destroy(struct efivar_entry *entry, void *data) +{ + efivar_entry_remove(entry); + kfree(entry); + return 0; +} + +static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct inode *inode = NULL; + struct dentry *root; + int err; + + sb->s_maxbytes = MAX_LFS_FILESIZE; + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = EFIVARFS_MAGIC; + sb->s_op = &efivarfs_ops; + sb->s_d_op = &efivarfs_d_ops; + sb->s_time_gran = 1; + + if (!efivar_supports_writes()) + sb->s_flags |= SB_RDONLY; + + inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); + if (!inode) + return -ENOMEM; + inode->i_op = &efivarfs_dir_inode_operations; + + root = d_make_root(inode); + sb->s_root = root; + if (!root) + return -ENOMEM; + + INIT_LIST_HEAD(&efivarfs_list); + + err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list); + if (err) + efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); + + return err; +} + +static int efivarfs_get_tree(struct fs_context *fc) +{ + return get_tree_single(fc, efivarfs_fill_super); +} + +static int efivarfs_reconfigure(struct fs_context *fc) +{ + if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) { + pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n"); + return -EINVAL; + } + + return 0; +} + +static const struct fs_context_operations efivarfs_context_ops = { + .get_tree = efivarfs_get_tree, + .reconfigure = efivarfs_reconfigure, +}; + +static int efivarfs_init_fs_context(struct fs_context *fc) +{ + fc->ops = &efivarfs_context_ops; + return 0; +} + +static void efivarfs_kill_sb(struct super_block *sb) +{ + struct efivarfs_fs_info *sfi = sb->s_fs_info; + + kill_litter_super(sb); + + /* Remove all entries and destroy */ + efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL); + kfree(sfi); +} + +static struct file_system_type efivarfs_type = { + .owner = THIS_MODULE, + .name = "efivarfs", + .init_fs_context = efivarfs_init_fs_context, + .kill_sb = efivarfs_kill_sb, +}; + +static __init int efivarfs_init(void) +{ + if (!efivars_kobject()) + return -ENODEV; + + return register_filesystem(&efivarfs_type); +} + +static __exit void efivarfs_exit(void) +{ + unregister_filesystem(&efivarfs_type); +} + +MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); +MODULE_DESCRIPTION("EFI Variable Filesystem"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_FS("efivarfs"); + +module_init(efivarfs_init); +module_exit(efivarfs_exit); diff --git a/fs/efivarfs/vars.c b/fs/efivarfs/vars.c new file mode 100644 index 000000000..9e4f47808 --- /dev/null +++ b/fs/efivarfs/vars.c @@ -0,0 +1,722 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Originally from efivars.c + * + * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com> + * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com> + */ + +#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/device.h> +#include <linux/slab.h> +#include <linux/ctype.h> +#include <linux/ucs2_string.h> + +#include "internal.h" + +MODULE_IMPORT_NS(EFIVAR); + +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; +} + +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; +} + +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; + + 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 + * @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) +{ + unsigned long variable_name_size = 1024; + efi_char16_t *variable_name; + efi_status_t status; + efi_guid_t vendor_guid; + int err = 0; + + variable_name = kzalloc(variable_name_size, GFP_KERNEL); + if (!variable_name) { + printk(KERN_ERR "efivars: Memory allocation failed.\n"); + return -ENOMEM; + } + + err = efivar_lock(); + if (err) + 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 = efivar_get_next_variable(&variable_name_size, + variable_name, + &vendor_guid); + switch (status) { + case EFI_SUCCESS: + 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; + } + break; + case EFI_UNSUPPORTED: + err = -EOPNOTSUPP; + status = EFI_NOT_FOUND; + 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); + + efivar_unlock(); +free: + kfree(variable_name); + + return err; +} + +/** + * 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) +{ + int err; + + err = efivar_lock(); + if (err) + return err; + list_add(&entry->list, head); + efivar_unlock(); + + return 0; +} + +/** + * __efivar_entry_add - add entry to variable list + * @entry: entry to add to list + * @head: list head + */ +void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head) +{ + list_add(&entry->list, head); +} + +/** + * 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. + */ +void efivar_entry_remove(struct efivar_entry *entry) +{ + list_del(&entry->list); +} + +/* + * 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); + efivar_unlock(); +} + +/** + * 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) +{ + efi_status_t status; + int err; + + err = efivar_lock(); + if (err) + return err; + + status = efivar_set_variable_locked(entry->var.VariableName, + &entry->var.VendorGuid, + 0, 0, NULL, false); + if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) { + efivar_unlock(); + return efi_status_to_err(status); + } + + efivar_entry_list_del_unlock(entry); + return 0; +} + +/** + * 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) +{ + efi_status_t status; + int err; + + *size = 0; + + err = efivar_lock(); + if (err) + return err; + + status = efivar_get_variable(entry->var.VariableName, + &entry->var.VendorGuid, NULL, size, NULL); + efivar_unlock(); + + if (status != EFI_BUFFER_TOO_SMALL) + return efi_status_to_err(status); + + return 0; +} + +/** + * __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; + + status = efivar_get_variable(entry->var.VariableName, + &entry->var.VendorGuid, + attributes, size, data); + + return efi_status_to_err(status); +} + +/** + * 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) +{ + int err; + + err = efivar_lock(); + if (err) + return err; + err = __efivar_entry_get(entry, attributes, size, data); + efivar_unlock(); + + return 0; +} + +/** + * 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) +{ + 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). + */ + err = efivar_lock(); + if (err) + return err; + + status = efivar_set_variable_locked(name, vendor, attributes, *size, + data, false); + 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 = efivar_get_variable(entry->var.VariableName, + &entry->var.VendorGuid, + NULL, size, NULL); + + if (status == EFI_NOT_FOUND) + efivar_entry_list_del_unlock(entry); + else + efivar_unlock(); + + if (status && status != EFI_BUFFER_TOO_SMALL) + return efi_status_to_err(status); + + return 0; + +out: + efivar_unlock(); + return err; + +} + +/** + * 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) +{ + struct efivar_entry *entry, *n; + int err = 0; + + err = efivar_lock(); + if (err) + return err; + + list_for_each_entry_safe(entry, n, head, list) { + err = func(entry, data); + if (err) + break; + } + efivar_unlock(); + + return err; +} |