1 /* user_defined.c: user defined key type 2 * 3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/init.h> 14 #include <linux/slab.h> 15 #include <linux/seq_file.h> 16 #include <linux/err.h> 17 #include <keys/user-type.h> 18 #include <asm/uaccess.h> 19 #include "internal.h" 20 21 /* 22 * user defined keys take an arbitrary string as the description and an 23 * arbitrary blob of data as the payload 24 */ 25 struct key_type key_type_user = { 26 .name = "user", 27 .instantiate = user_instantiate, 28 .update = user_update, 29 .match = user_match, 30 .revoke = user_revoke, 31 .destroy = user_destroy, 32 .describe = user_describe, 33 .read = user_read, 34 }; 35 36 EXPORT_SYMBOL_GPL(key_type_user); 37 38 /* 39 * instantiate a user defined key 40 */ 41 int user_instantiate(struct key *key, const void *data, size_t datalen) 42 { 43 struct user_key_payload *upayload; 44 int ret; 45 46 ret = -EINVAL; 47 if (datalen <= 0 || datalen > 32767 || !data) 48 goto error; 49 50 ret = key_payload_reserve(key, datalen); 51 if (ret < 0) 52 goto error; 53 54 ret = -ENOMEM; 55 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 56 if (!upayload) 57 goto error; 58 59 /* attach the data */ 60 upayload->datalen = datalen; 61 memcpy(upayload->data, data, datalen); 62 rcu_assign_pointer(key->payload.data, upayload); 63 ret = 0; 64 65 error: 66 return ret; 67 } 68 69 EXPORT_SYMBOL_GPL(user_instantiate); 70 71 /* 72 * update a user defined key 73 * - the key's semaphore is write-locked 74 */ 75 int user_update(struct key *key, const void *data, size_t datalen) 76 { 77 struct user_key_payload *upayload, *zap; 78 int ret; 79 80 ret = -EINVAL; 81 if (datalen <= 0 || datalen > 32767 || !data) 82 goto error; 83 84 /* construct a replacement payload */ 85 ret = -ENOMEM; 86 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 87 if (!upayload) 88 goto error; 89 90 upayload->datalen = datalen; 91 memcpy(upayload->data, data, datalen); 92 93 /* check the quota and attach the new data */ 94 zap = upayload; 95 96 ret = key_payload_reserve(key, datalen); 97 98 if (ret == 0) { 99 /* attach the new data, displacing the old */ 100 zap = key->payload.data; 101 rcu_assign_pointer(key->payload.data, upayload); 102 key->expiry = 0; 103 } 104 105 kfree_rcu(zap, rcu); 106 107 error: 108 return ret; 109 } 110 111 EXPORT_SYMBOL_GPL(user_update); 112 113 /* 114 * match users on their name 115 */ 116 int user_match(const struct key *key, const void *description) 117 { 118 return strcmp(key->description, description) == 0; 119 } 120 121 EXPORT_SYMBOL_GPL(user_match); 122 123 /* 124 * dispose of the links from a revoked keyring 125 * - called with the key sem write-locked 126 */ 127 void user_revoke(struct key *key) 128 { 129 struct user_key_payload *upayload = key->payload.data; 130 131 /* clear the quota */ 132 key_payload_reserve(key, 0); 133 134 if (upayload) { 135 rcu_assign_pointer(key->payload.data, NULL); 136 kfree_rcu(upayload, rcu); 137 } 138 } 139 140 EXPORT_SYMBOL(user_revoke); 141 142 /* 143 * dispose of the data dangling from the corpse of a user key 144 */ 145 void user_destroy(struct key *key) 146 { 147 struct user_key_payload *upayload = key->payload.data; 148 149 kfree(upayload); 150 } 151 152 EXPORT_SYMBOL_GPL(user_destroy); 153 154 /* 155 * describe the user key 156 */ 157 void user_describe(const struct key *key, struct seq_file *m) 158 { 159 seq_puts(m, key->description); 160 if (key_is_instantiated(key)) 161 seq_printf(m, ": %u", key->datalen); 162 } 163 164 EXPORT_SYMBOL_GPL(user_describe); 165 166 /* 167 * read the key data 168 * - the key's semaphore is read-locked 169 */ 170 long user_read(const struct key *key, char __user *buffer, size_t buflen) 171 { 172 struct user_key_payload *upayload; 173 long ret; 174 175 upayload = rcu_dereference_key(key); 176 ret = upayload->datalen; 177 178 /* we can return the data as is */ 179 if (buffer && buflen > 0) { 180 if (buflen > upayload->datalen) 181 buflen = upayload->datalen; 182 183 if (copy_to_user(buffer, upayload->data, buflen) != 0) 184 ret = -EFAULT; 185 } 186 187 return ret; 188 } 189 190 EXPORT_SYMBOL_GPL(user_read); 191