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 const struct file_operations efivarfs_file_operations = { 110 .open = simple_open, 111 .read = efivarfs_file_read, 112 .write = efivarfs_file_write, 113 .llseek = no_llseek, 114 }; 115