/* * Copyright (C) 2012 Red Hat, Inc. * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/ctype.h> #include <linux/efi.h> #include <linux/fs.h> #include <linux/module.h> #include <linux/pagemap.h> #include <linux/ucs2_string.h> #include <linux/slab.h> #include <linux/magic.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, .show_options = generic_show_options, }; static struct super_block *efivarfs_sb; /* * 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 *parent, const struct inode *pinode, const struct dentry *dentry, const struct inode *inode, 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, const struct inode *inode, struct qstr *qstr) { unsigned long hash = init_name_hash(); 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; } /* * Retaining negative dentries for an in-memory filesystem just wastes * memory and lookup time: arrange for them to be deleted immediately. */ static int efivarfs_delete_dentry(const struct dentry *dentry) { return 1; } static struct dentry_operations efivarfs_d_ops = { .d_compare = efivarfs_d_compare, .d_hash = efivarfs_d_hash, .d_delete = efivarfs_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(NULL, NULL, &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, i; int err = -ENOMEM; entry = kmalloc(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_strlen(entry->var.VariableName); /* name, plus '-', plus GUID, plus NUL*/ name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); if (!name) goto fail; for (i = 0; i < len; i++) name[i] = entry->var.VariableName[i] & 0xFF; name[len] = '-'; efi_guid_unparse(&entry->var.VendorGuid, name + len + 1); name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0); if (!inode) goto fail_name; dentry = efivarfs_alloc_dentry(root, name); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); goto fail_inode; } /* copied by the above to local storage in the dentry. */ kfree(name); efivar_entry_size(entry, &size); efivar_entry_add(entry, &efivarfs_list); mutex_lock(&inode->i_mutex); inode->i_private = entry; i_size_write(inode, size + sizeof(entry->var.Attributes)); mutex_unlock(&inode->i_mutex); 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, void *data, int silent) { struct inode *inode = NULL; struct dentry *root; int err; efivarfs_sb = sb; sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = EFIVARFS_MAGIC; sb->s_op = &efivarfs_ops; sb->s_d_op = &efivarfs_d_ops; sb->s_time_gran = 1; inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0); 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, false, true, &efivarfs_list); if (err) __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); return err; } static struct dentry *efivarfs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return mount_single(fs_type, flags, data, efivarfs_fill_super); } static void efivarfs_kill_sb(struct super_block *sb) { kill_litter_super(sb); efivarfs_sb = NULL; /* Remove all entries and destroy */ __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); } static struct file_system_type efivarfs_type = { .name = "efivarfs", .mount = efivarfs_mount, .kill_sb = efivarfs_kill_sb, }; static __init int efivarfs_init(void) { if (!efi_enabled(EFI_RUNTIME_SERVICES)) return 0; if (!efivars_kobject()) return 0; return register_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);