1 /* 2 * Copyright (C) 2012 Red Hat, Inc. 3 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10 #include <linux/efi.h> 11 #include <linux/fs.h> 12 #include <linux/slab.h> 13 14 #include "internal.h" 15 16 static ssize_t efivarfs_file_write(struct file *file, 17 const char __user *userbuf, size_t count, loff_t *ppos) 18 { 19 struct efivar_entry *var = file->private_data; 20 void *data; 21 u32 attributes; 22 struct inode *inode = file->f_mapping->host; 23 unsigned long datasize = count - sizeof(attributes); 24 ssize_t bytes; 25 bool set = false; 26 27 if (count < sizeof(attributes)) 28 return -EINVAL; 29 30 if (copy_from_user(&attributes, userbuf, sizeof(attributes))) 31 return -EFAULT; 32 33 if (attributes & ~(EFI_VARIABLE_MASK)) 34 return -EINVAL; 35 36 data = memdup_user(userbuf + sizeof(attributes), datasize); 37 if (IS_ERR(data)) 38 return PTR_ERR(data); 39 40 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 41 data, &set); 42 if (!set && bytes) { 43 if (bytes == -ENOENT) 44 bytes = -EIO; 45 goto out; 46 } 47 48 if (bytes == -ENOENT) { 49 drop_nlink(inode); 50 d_delete(file->f_path.dentry); 51 dput(file->f_path.dentry); 52 } else { 53 inode_lock(inode); 54 i_size_write(inode, datasize + sizeof(attributes)); 55 inode_unlock(inode); 56 } 57 58 bytes = count; 59 60 out: 61 kfree(data); 62 63 return bytes; 64 } 65 66 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 67 size_t count, loff_t *ppos) 68 { 69 struct efivar_entry *var = file->private_data; 70 unsigned long datasize = 0; 71 u32 attributes; 72 void *data; 73 ssize_t size = 0; 74 int err; 75 76 err = efivar_entry_size(var, &datasize); 77 78 /* 79 * efivarfs represents uncommitted variables with 80 * zero-length files. Reading them should return EOF. 81 */ 82 if (err == -ENOENT) 83 return 0; 84 else if (err) 85 return err; 86 87 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 88 89 if (!data) 90 return -ENOMEM; 91 92 size = efivar_entry_get(var, &attributes, &datasize, 93 data + sizeof(attributes)); 94 if (size) 95 goto out_free; 96 97 memcpy(data, &attributes, sizeof(attributes)); 98 size = simple_read_from_buffer(userbuf, count, ppos, 99 data, datasize + sizeof(attributes)); 100 out_free: 101 kfree(data); 102 103 return size; 104 } 105 106 const struct file_operations efivarfs_file_operations = { 107 .open = simple_open, 108 .read = efivarfs_file_read, 109 .write = efivarfs_file_write, 110 .llseek = no_llseek, 111 }; 112