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/delay.h> 12 #include <linux/fs.h> 13 #include <linux/slab.h> 14 #include <linux/mount.h> 15 16 #include "internal.h" 17 18 static ssize_t efivarfs_file_write(struct file *file, 19 const char __user *userbuf, size_t count, loff_t *ppos) 20 { 21 struct efivar_entry *var = file->private_data; 22 void *data; 23 u32 attributes; 24 struct inode *inode = file->f_mapping->host; 25 unsigned long datasize = count - sizeof(attributes); 26 ssize_t bytes; 27 bool set = false; 28 29 if (count < sizeof(attributes)) 30 return -EINVAL; 31 32 if (copy_from_user(&attributes, userbuf, sizeof(attributes))) 33 return -EFAULT; 34 35 if (attributes & ~(EFI_VARIABLE_MASK)) 36 return -EINVAL; 37 38 data = memdup_user(userbuf + sizeof(attributes), datasize); 39 if (IS_ERR(data)) 40 return PTR_ERR(data); 41 42 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 43 data, &set); 44 if (!set && bytes) { 45 if (bytes == -ENOENT) 46 bytes = -EIO; 47 goto out; 48 } 49 50 if (bytes == -ENOENT) { 51 drop_nlink(inode); 52 d_delete(file->f_path.dentry); 53 dput(file->f_path.dentry); 54 } else { 55 inode_lock(inode); 56 i_size_write(inode, datasize + sizeof(attributes)); 57 inode_unlock(inode); 58 } 59 60 bytes = count; 61 62 out: 63 kfree(data); 64 65 return bytes; 66 } 67 68 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 69 size_t count, loff_t *ppos) 70 { 71 struct efivar_entry *var = file->private_data; 72 unsigned long datasize = 0; 73 u32 attributes; 74 void *data; 75 ssize_t size = 0; 76 int err; 77 78 while (!__ratelimit(&file->f_cred->user->ratelimit)) { 79 if (!msleep_interruptible(50)) 80 return -EINTR; 81 } 82 83 err = efivar_entry_size(var, &datasize); 84 85 /* 86 * efivarfs represents uncommitted variables with 87 * zero-length files. Reading them should return EOF. 88 */ 89 if (err == -ENOENT) 90 return 0; 91 else if (err) 92 return err; 93 94 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 95 96 if (!data) 97 return -ENOMEM; 98 99 size = efivar_entry_get(var, &attributes, &datasize, 100 data + sizeof(attributes)); 101 if (size) 102 goto out_free; 103 104 memcpy(data, &attributes, sizeof(attributes)); 105 size = simple_read_from_buffer(userbuf, count, ppos, 106 data, datasize + sizeof(attributes)); 107 out_free: 108 kfree(data); 109 110 return size; 111 } 112 113 static int 114 efivarfs_ioc_getxflags(struct file *file, void __user *arg) 115 { 116 struct inode *inode = file->f_mapping->host; 117 unsigned int i_flags; 118 unsigned int flags = 0; 119 120 i_flags = inode->i_flags; 121 if (i_flags & S_IMMUTABLE) 122 flags |= FS_IMMUTABLE_FL; 123 124 if (copy_to_user(arg, &flags, sizeof(flags))) 125 return -EFAULT; 126 return 0; 127 } 128 129 static int 130 efivarfs_ioc_setxflags(struct file *file, void __user *arg) 131 { 132 struct inode *inode = file->f_mapping->host; 133 unsigned int flags; 134 unsigned int i_flags = 0; 135 int error; 136 137 if (!inode_owner_or_capable(inode)) 138 return -EACCES; 139 140 if (copy_from_user(&flags, arg, sizeof(flags))) 141 return -EFAULT; 142 143 if (flags & ~FS_IMMUTABLE_FL) 144 return -EOPNOTSUPP; 145 146 if (!capable(CAP_LINUX_IMMUTABLE)) 147 return -EPERM; 148 149 if (flags & FS_IMMUTABLE_FL) 150 i_flags |= S_IMMUTABLE; 151 152 153 error = mnt_want_write_file(file); 154 if (error) 155 return error; 156 157 inode_lock(inode); 158 inode_set_flags(inode, i_flags, S_IMMUTABLE); 159 inode_unlock(inode); 160 161 mnt_drop_write_file(file); 162 163 return 0; 164 } 165 166 static long 167 efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p) 168 { 169 void __user *arg = (void __user *)p; 170 171 switch (cmd) { 172 case FS_IOC_GETFLAGS: 173 return efivarfs_ioc_getxflags(file, arg); 174 case FS_IOC_SETFLAGS: 175 return efivarfs_ioc_setxflags(file, arg); 176 } 177 178 return -ENOTTY; 179 } 180 181 const struct file_operations efivarfs_file_operations = { 182 .open = simple_open, 183 .read = efivarfs_file_read, 184 .write = efivarfs_file_write, 185 .llseek = no_llseek, 186 .unlocked_ioctl = efivarfs_file_ioctl, 187 }; 188