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 inode_lock(inode); 40 if (var->removed) { 41 /* 42 * file got removed; don't allow a set. Caused by an 43 * unsuccessful create or successful delete write 44 * racing with us. 45 */ 46 bytes = -EIO; 47 goto out; 48 } 49 50 bytes = efivar_entry_set_get_size(var, attributes, &datasize, 51 data, &set); 52 if (!set) { 53 if (bytes == -ENOENT) 54 bytes = -EIO; 55 goto out; 56 } 57 58 if (bytes == -ENOENT) { 59 /* 60 * zero size signals to release that the write deleted 61 * the variable 62 */ 63 i_size_write(inode, 0); 64 } else { 65 i_size_write(inode, datasize + sizeof(attributes)); 66 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); 67 } 68 69 bytes = count; 70 71 out: 72 inode_unlock(inode); 73 74 kfree(data); 75 76 return bytes; 77 } 78 79 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 80 size_t count, loff_t *ppos) 81 { 82 struct efivar_entry *var = file->private_data; 83 unsigned long datasize = 0; 84 u32 attributes; 85 void *data; 86 ssize_t size = 0; 87 int err; 88 89 while (!__ratelimit(&file->f_cred->user->ratelimit)) 90 msleep(50); 91 92 err = efivar_entry_size(var, &datasize); 93 94 /* 95 * efivarfs represents uncommitted variables with 96 * zero-length files. Reading them should return EOF. 97 */ 98 if (err == -ENOENT) 99 return 0; 100 else if (err) 101 return err; 102 103 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 104 105 if (!data) 106 return -ENOMEM; 107 108 size = efivar_entry_get(var, &attributes, &datasize, 109 data + sizeof(attributes)); 110 if (size) 111 goto out_free; 112 113 memcpy(data, &attributes, sizeof(attributes)); 114 size = simple_read_from_buffer(userbuf, count, ppos, 115 data, datasize + sizeof(attributes)); 116 out_free: 117 kfree(data); 118 119 return size; 120 } 121 122 static int efivarfs_file_release(struct inode *inode, struct file *file) 123 { 124 struct efivar_entry *var = inode->i_private; 125 126 inode_lock(inode); 127 var->removed = (--var->open_count == 0 && i_size_read(inode) == 0); 128 inode_unlock(inode); 129 130 if (var->removed) 131 simple_recursive_removal(file->f_path.dentry, NULL); 132 133 return 0; 134 } 135 136 static int efivarfs_file_open(struct inode *inode, struct file *file) 137 { 138 struct efivar_entry *entry = inode->i_private; 139 140 file->private_data = entry; 141 142 inode_lock(inode); 143 entry->open_count++; 144 inode_unlock(inode); 145 146 return 0; 147 } 148 149 const struct file_operations efivarfs_file_operations = { 150 .open = efivarfs_file_open, 151 .read = efivarfs_file_read, 152 .write = efivarfs_file_write, 153 .release = efivarfs_file_release, 154 }; 155