1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012 Red Hat, Inc. 4 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> 5 */ 6 7 #include <linux/efi.h> 8 #include <linux/delay.h> 9 #include <linux/fs.h> 10 #include <linux/slab.h> 11 #include <linux/mount.h> 12 13 #include "internal.h" 14 15 static ssize_t efivarfs_file_write(struct file *file, 16 const char __user *userbuf, size_t count, loff_t *ppos) 17 { 18 struct efivar_entry *var = file->private_data; 19 void *data; 20 u32 attributes; 21 struct inode *inode = file->f_mapping->host; 22 unsigned long datasize = count - sizeof(attributes); 23 ssize_t bytes; 24 bool set = false; 25 26 if (count < sizeof(attributes)) 27 return -EINVAL; 28 29 if (copy_from_user(&attributes, userbuf, sizeof(attributes))) 30 return -EFAULT; 31 32 if (attributes & ~(EFI_VARIABLE_MASK)) 33 return -EINVAL; 34 35 data = memdup_user(userbuf + sizeof(attributes), datasize); 36 if (IS_ERR(data)) 37 return PTR_ERR(data); 38 39 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 40 data, &set); 41 if (!set && bytes) { 42 if (bytes == -ENOENT) 43 bytes = -EIO; 44 goto out; 45 } 46 47 if (bytes == -ENOENT) { 48 drop_nlink(inode); 49 d_delete(file->f_path.dentry); 50 dput(file->f_path.dentry); 51 } else { 52 inode_lock(inode); 53 i_size_write(inode, datasize + sizeof(attributes)); 54 inode->i_mtime = current_time(inode); 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 while (!__ratelimit(&file->f_cred->user->ratelimit)) 77 msleep(50); 78 79 err = efivar_entry_size(var, &datasize); 80 81 /* 82 * efivarfs represents uncommitted variables with 83 * zero-length files. Reading them should return EOF. 84 */ 85 if (err == -ENOENT) 86 return 0; 87 else if (err) 88 return err; 89 90 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 91 92 if (!data) 93 return -ENOMEM; 94 95 size = efivar_entry_get(var, &attributes, &datasize, 96 data + sizeof(attributes)); 97 if (size) 98 goto out_free; 99 100 memcpy(data, &attributes, sizeof(attributes)); 101 size = simple_read_from_buffer(userbuf, count, ppos, 102 data, datasize + sizeof(attributes)); 103 out_free: 104 kfree(data); 105 106 return size; 107 } 108 109 static inline unsigned int efivarfs_getflags(struct inode *inode) 110 { 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 return flags; 118 } 119 120 static int 121 efivarfs_ioc_getxflags(struct file *file, void __user *arg) 122 { 123 struct inode *inode = file->f_mapping->host; 124 unsigned int flags = efivarfs_getflags(inode); 125 126 if (copy_to_user(arg, &flags, sizeof(flags))) 127 return -EFAULT; 128 return 0; 129 } 130 131 static int 132 efivarfs_ioc_setxflags(struct file *file, void __user *arg) 133 { 134 struct inode *inode = file->f_mapping->host; 135 unsigned int flags; 136 unsigned int i_flags = 0; 137 unsigned int oldflags = efivarfs_getflags(inode); 138 int error; 139 140 if (!inode_owner_or_capable(&init_user_ns, inode)) 141 return -EACCES; 142 143 if (copy_from_user(&flags, arg, sizeof(flags))) 144 return -EFAULT; 145 146 if (flags & ~FS_IMMUTABLE_FL) 147 return -EOPNOTSUPP; 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); 158 159 error = vfs_ioc_setflags_prepare(inode, oldflags, flags); 160 if (error) 161 goto out; 162 163 inode_set_flags(inode, i_flags, S_IMMUTABLE); 164 out: 165 inode_unlock(inode); 166 mnt_drop_write_file(file); 167 return error; 168 } 169 170 static long 171 efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p) 172 { 173 void __user *arg = (void __user *)p; 174 175 switch (cmd) { 176 case FS_IOC_GETFLAGS: 177 return efivarfs_ioc_getxflags(file, arg); 178 case FS_IOC_SETFLAGS: 179 return efivarfs_ioc_setxflags(file, arg); 180 } 181 182 return -ENOTTY; 183 } 184 185 const struct file_operations efivarfs_file_operations = { 186 .open = simple_open, 187 .read = efivarfs_file_read, 188 .write = efivarfs_file_write, 189 .llseek = no_llseek, 190 .unlocked_ioctl = efivarfs_file_ioctl, 191 }; 192