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 = 0; 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 = kmalloc(datasize, GFP_KERNEL); 37 if (!data) 38 return -ENOMEM; 39 40 if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) { 41 bytes = -EFAULT; 42 goto out; 43 } 44 45 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 46 data, &set); 47 if (!set && bytes) { 48 if (bytes == -ENOENT) 49 bytes = -EIO; 50 goto out; 51 } 52 53 if (bytes == -ENOENT) { 54 drop_nlink(inode); 55 d_delete(file->f_dentry); 56 dput(file->f_dentry); 57 } else { 58 mutex_lock(&inode->i_mutex); 59 i_size_write(inode, datasize + sizeof(attributes)); 60 mutex_unlock(&inode->i_mutex); 61 } 62 63 bytes = count; 64 65 out: 66 kfree(data); 67 68 return bytes; 69 } 70 71 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 72 size_t count, loff_t *ppos) 73 { 74 struct efivar_entry *var = file->private_data; 75 unsigned long datasize = 0; 76 u32 attributes; 77 void *data; 78 ssize_t size = 0; 79 int err; 80 81 err = efivar_entry_size(var, &datasize); 82 83 /* 84 * efivarfs represents uncommitted variables with 85 * zero-length files. Reading them should return EOF. 86 */ 87 if (err == -ENOENT) 88 return 0; 89 else if (err) 90 return err; 91 92 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 93 94 if (!data) 95 return -ENOMEM; 96 97 size = efivar_entry_get(var, &attributes, &datasize, 98 data + sizeof(attributes)); 99 if (size) 100 goto out_free; 101 102 memcpy(data, &attributes, sizeof(attributes)); 103 size = simple_read_from_buffer(userbuf, count, ppos, 104 data, datasize + sizeof(attributes)); 105 out_free: 106 kfree(data); 107 108 return size; 109 } 110 111 const struct file_operations efivarfs_file_operations = { 112 .open = simple_open, 113 .read = efivarfs_file_read, 114 .write = efivarfs_file_write, 115 .llseek = no_llseek, 116 }; 117