/* * 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/efi.h> #include <linux/fs.h> #include <linux/ctype.h> #include <linux/slab.h> #include "internal.h" struct inode *efivarfs_get_inode(struct super_block *sb, const struct inode *dir, int mode, dev_t dev) { 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; switch (mode & S_IFMT) { case S_IFREG: 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) { static const char dashes[EFI_VARIABLE_GUID_LEN] = { [8] = 1, [13] = 1, [18] = 1, [23] = 1 }; const char *s = str + len - EFI_VARIABLE_GUID_LEN; int i; /* * 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 */ for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) { if (dashes[i]) { if (*s++ != '-') return false; } else { if (!isxdigit(*s++)) return false; } } return true; } static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid) { guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]); guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]); guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]); guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]); guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]); guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]); guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]); guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]); guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]); guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]); guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]); guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]); guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]); guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]); guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]); guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]); } static int efivarfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl) { struct inode *inode; struct efivar_entry *var; int namelen, i = 0, err = 0; if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len)) return -EINVAL; inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0); if (!inode) return -ENOMEM; var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL); if (!var) { err = -ENOMEM; goto out; } /* length of the variable name itself: remove GUID and separator */ namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1; efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); for (i = 0; i < namelen; i++) var->var.VariableName[i] = dentry->d_name.name[i]; var->var.VariableName[i] = '\0'; inode->i_private = var; efivar_entry_add(var, &efivarfs_list); d_instantiate(dentry, inode); dget(dentry); out: if (err) { kfree(var); iput(inode); } return err; } static int efivarfs_unlink(struct inode *dir, struct dentry *dentry) { struct efivar_entry *var = dentry->d_inode->i_private; if (efivar_entry_delete(var)) return -EINVAL; drop_nlink(dentry->d_inode); dput(dentry); return 0; }; const struct inode_operations efivarfs_dir_inode_operations = { .lookup = simple_lookup, .unlink = efivarfs_unlink, .create = efivarfs_create, };