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 #include <linux/mount.h> 14 15 #include "internal.h" 16 17 static ssize_t efivarfs_file_write(struct file *file, 18 const char __user *userbuf, size_t count, loff_t *ppos) 19 { 20 struct efivar_entry *var = file->private_data; 21 void *data; 22 u32 attributes; 23 struct inode *inode = file->f_mapping->host; 24 unsigned long datasize = count - sizeof(attributes); 25 ssize_t bytes; 26 bool set = false; 27 28 if (count < sizeof(attributes)) 29 return -EINVAL; 30 31 if (copy_from_user(&attributes, userbuf, sizeof(attributes))) 32 return -EFAULT; 33 34 if (attributes & ~(EFI_VARIABLE_MASK)) 35 return -EINVAL; 36 37 data = memdup_user(userbuf + sizeof(attributes), datasize); 38 if (IS_ERR(data)) 39 return PTR_ERR(data); 40 41 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 42 data, &set); 43 if (!set && bytes) { 44 if (bytes == -ENOENT) 45 bytes = -EIO; 46 goto out; 47 } 48 49 if (bytes == -ENOENT) { 50 drop_nlink(inode); 51 d_delete(file->f_path.dentry); 52 dput(file->f_path.dentry); 53 } else { 54 inode_lock(inode); 55 i_size_write(inode, datasize + sizeof(attributes)); 56 inode_unlock(inode); 57 } 58 59 bytes = count; 60 61 out: 62 kfree(data); 63 64 return bytes; 65 } 66 67 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 68 size_t count, loff_t *ppos) 69 { 70 struct efivar_entry *var = file->private_data; 71 unsigned long datasize = 0; 72 u32 attributes; 73 void *data; 74 ssize_t size = 0; 75 int err; 76 77 err = efivar_entry_size(var, &datasize); 78 79 /* 80 * efivarfs represents uncommitted variables with 81 * zero-length files. Reading them should return EOF. 82 */ 83 if (err == -ENOENT) 84 return 0; 85 else if (err) 86 return err; 87 88 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 89 90 if (!data) 91 return -ENOMEM; 92 93 size = efivar_entry_get(var, &attributes, &datasize, 94 data + sizeof(attributes)); 95 if (size) 96 goto out_free; 97 98 memcpy(data, &attributes, sizeof(attributes)); 99 size = simple_read_from_buffer(userbuf, count, ppos, 100 data, datasize + sizeof(attributes)); 101 out_free: 102 kfree(data); 103 104 return size; 105 } 106 107 static int 108 efivarfs_ioc_getxflags(struct file *file, void __user *arg) 109 { 110 struct inode *inode = file->f_mapping->host; 111 unsigned int i_flags; 112 unsigned int flags = 0; 113 114 i_flags = inode->i_flags; 115 if (i_flags & S_IMMUTABLE) 116 flags |= FS_IMMUTABLE_FL; 117 118 if (copy_to_user(arg, &flags, sizeof(flags))) 119 return -EFAULT; 120 return 0; 121 } 122 123 static int 124 efivarfs_ioc_setxflags(struct file *file, void __user *arg) 125 { 126 struct inode *inode = file->f_mapping->host; 127 unsigned int flags; 128 unsigned int i_flags = 0; 129 int error; 130 131 if (!inode_owner_or_capable(inode)) 132 return -EACCES; 133 134 if (copy_from_user(&flags, arg, sizeof(flags))) 135 return -EFAULT; 136 137 if (flags & ~FS_IMMUTABLE_FL) 138 return -EOPNOTSUPP; 139 140 if (!capable(CAP_LINUX_IMMUTABLE)) 141 return -EPERM; 142 143 if (flags & FS_IMMUTABLE_FL) 144 i_flags |= S_IMMUTABLE; 145 146 147 error = mnt_want_write_file(file); 148 if (error) 149 return error; 150 151 inode_lock(inode); 152 inode_set_flags(inode, i_flags, S_IMMUTABLE); 153 inode_unlock(inode); 154 155 mnt_drop_write_file(file); 156 157 return 0; 158 } 159 160 long 161 efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p) 162 { 163 void __user *arg = (void __user *)p; 164 165 switch (cmd) { 166 case FS_IOC_GETFLAGS: 167 return efivarfs_ioc_getxflags(file, arg); 168 case FS_IOC_SETFLAGS: 169 return efivarfs_ioc_setxflags(file, arg); 170 } 171 172 return -ENOTTY; 173 } 174 175 const struct file_operations efivarfs_file_operations = { 176 .open = simple_open, 177 .read = efivarfs_file_read, 178 .write = efivarfs_file_write, 179 .llseek = no_llseek, 180 .unlocked_ioctl = efivarfs_file_ioctl, 181 }; 182