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 * FIXME: temporary workaround for fwupdate, signal 61 * failed write with a 1 to keep created but not 62 * written files 63 */ 64 i_size_write(inode, 1); 65 } else { 66 i_size_write(inode, datasize + sizeof(attributes)); 67 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); 68 } 69 70 bytes = count; 71 72 out: 73 inode_unlock(inode); 74 75 kfree(data); 76 77 return bytes; 78 } 79 80 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, 81 size_t count, loff_t *ppos) 82 { 83 struct efivar_entry *var = file->private_data; 84 unsigned long datasize = 0; 85 u32 attributes; 86 void *data; 87 ssize_t size = 0; 88 int err; 89 90 while (!__ratelimit(&file->f_cred->user->ratelimit)) 91 msleep(50); 92 93 err = efivar_entry_size(var, &datasize); 94 95 /* 96 * efivarfs represents uncommitted variables with 97 * zero-length files. Reading them should return EOF. 98 */ 99 if (err == -ENOENT) 100 return 0; 101 else if (err) 102 return err; 103 104 data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL); 105 106 if (!data) 107 return -ENOMEM; 108 109 size = efivar_entry_get(var, &attributes, &datasize, 110 data + sizeof(attributes)); 111 if (size) 112 goto out_free; 113 114 memcpy(data, &attributes, sizeof(attributes)); 115 size = simple_read_from_buffer(userbuf, count, ppos, 116 data, datasize + sizeof(attributes)); 117 out_free: 118 kfree(data); 119 120 return size; 121 } 122 123 static int efivarfs_file_release(struct inode *inode, struct file *file) 124 { 125 struct efivar_entry *var = inode->i_private; 126 127 inode_lock(inode); 128 /* FIXME: temporary work around for fwupdate */ 129 var->removed = (--var->open_count == 0 && i_size_read(inode) == 1); 130 inode_unlock(inode); 131 132 if (var->removed) 133 simple_recursive_removal(file->f_path.dentry, NULL); 134 135 return 0; 136 } 137 138 static int efivarfs_file_open(struct inode *inode, struct file *file) 139 { 140 struct efivar_entry *entry = inode->i_private; 141 142 file->private_data = entry; 143 144 inode_lock(inode); 145 entry->open_count++; 146 inode_unlock(inode); 147 148 return 0; 149 } 150 151 const struct file_operations efivarfs_file_operations = { 152 .open = efivarfs_file_open, 153 .read = efivarfs_file_read, 154 .write = efivarfs_file_write, 155 .release = efivarfs_file_release, 156 }; 157