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/sched.h> 15 #include <linux/slab.h> 16 #include <linux/seq_file.h> 17 #include <linux/err.h> 18 #include <keys/user-type.h> 19 #include <asm/uaccess.h> 20 #include "internal.h" 21 22 /* 23 * user defined keys take an arbitrary string as the description and an 24 * arbitrary blob of data as the payload 25 */ 26 struct key_type key_type_user = { 27 .name = "user", 28 .instantiate = user_instantiate, 29 .duplicate = user_duplicate, 30 .update = user_update, 31 .match = user_match, 32 .destroy = user_destroy, 33 .describe = user_describe, 34 .read = user_read, 35 }; 36 37 EXPORT_SYMBOL_GPL(key_type_user); 38 39 /*****************************************************************************/ 40 /* 41 * instantiate a user defined key 42 */ 43 int user_instantiate(struct key *key, const void *data, size_t datalen) 44 { 45 struct user_key_payload *upayload; 46 int ret; 47 48 ret = -EINVAL; 49 if (datalen <= 0 || datalen > 32767 || !data) 50 goto error; 51 52 ret = key_payload_reserve(key, datalen); 53 if (ret < 0) 54 goto error; 55 56 ret = -ENOMEM; 57 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 58 if (!upayload) 59 goto error; 60 61 /* attach the data */ 62 upayload->datalen = datalen; 63 memcpy(upayload->data, data, datalen); 64 rcu_assign_pointer(key->payload.data, upayload); 65 ret = 0; 66 67 error: 68 return ret; 69 70 } /* end user_instantiate() */ 71 72 EXPORT_SYMBOL_GPL(user_instantiate); 73 74 /*****************************************************************************/ 75 /* 76 * duplicate a user defined key 77 * - both keys' semaphores are locked against further modification 78 * - the new key cannot yet be accessed 79 */ 80 int user_duplicate(struct key *key, const struct key *source) 81 { 82 struct user_key_payload *upayload, *spayload; 83 int ret; 84 85 /* just copy the payload */ 86 ret = -ENOMEM; 87 upayload = kmalloc(sizeof(*upayload) + source->datalen, GFP_KERNEL); 88 if (upayload) { 89 spayload = rcu_dereference(source->payload.data); 90 BUG_ON(source->datalen != spayload->datalen); 91 92 upayload->datalen = key->datalen = spayload->datalen; 93 memcpy(upayload->data, spayload->data, key->datalen); 94 95 key->payload.data = upayload; 96 ret = 0; 97 } 98 99 return ret; 100 101 } /* end user_duplicate() */ 102 103 EXPORT_SYMBOL_GPL(user_duplicate); 104 105 /*****************************************************************************/ 106 /* 107 * dispose of the old data from an updated user defined key 108 */ 109 static void user_update_rcu_disposal(struct rcu_head *rcu) 110 { 111 struct user_key_payload *upayload; 112 113 upayload = container_of(rcu, struct user_key_payload, rcu); 114 115 kfree(upayload); 116 117 } /* end user_update_rcu_disposal() */ 118 119 /*****************************************************************************/ 120 /* 121 * update a user defined key 122 * - the key's semaphore is write-locked 123 */ 124 int user_update(struct key *key, const void *data, size_t datalen) 125 { 126 struct user_key_payload *upayload, *zap; 127 int ret; 128 129 ret = -EINVAL; 130 if (datalen <= 0 || datalen > 32767 || !data) 131 goto error; 132 133 /* construct a replacement payload */ 134 ret = -ENOMEM; 135 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 136 if (!upayload) 137 goto error; 138 139 upayload->datalen = datalen; 140 memcpy(upayload->data, data, datalen); 141 142 /* check the quota and attach the new data */ 143 zap = upayload; 144 145 ret = key_payload_reserve(key, datalen); 146 147 if (ret == 0) { 148 /* attach the new data, displacing the old */ 149 zap = key->payload.data; 150 rcu_assign_pointer(key->payload.data, upayload); 151 key->expiry = 0; 152 } 153 154 call_rcu(&zap->rcu, user_update_rcu_disposal); 155 156 error: 157 return ret; 158 159 } /* end user_update() */ 160 161 EXPORT_SYMBOL_GPL(user_update); 162 163 /*****************************************************************************/ 164 /* 165 * match users on their name 166 */ 167 int user_match(const struct key *key, const void *description) 168 { 169 return strcmp(key->description, description) == 0; 170 171 } /* end user_match() */ 172 173 EXPORT_SYMBOL_GPL(user_match); 174 175 /*****************************************************************************/ 176 /* 177 * dispose of the data dangling from the corpse of a user 178 */ 179 void user_destroy(struct key *key) 180 { 181 struct user_key_payload *upayload = key->payload.data; 182 183 kfree(upayload); 184 185 } /* end user_destroy() */ 186 187 EXPORT_SYMBOL_GPL(user_destroy); 188 189 /*****************************************************************************/ 190 /* 191 * describe the user key 192 */ 193 void user_describe(const struct key *key, struct seq_file *m) 194 { 195 seq_puts(m, key->description); 196 197 seq_printf(m, ": %u", key->datalen); 198 199 } /* end user_describe() */ 200 201 EXPORT_SYMBOL_GPL(user_describe); 202 203 /*****************************************************************************/ 204 /* 205 * read the key data 206 * - the key's semaphore is read-locked 207 */ 208 long user_read(const struct key *key, char __user *buffer, size_t buflen) 209 { 210 struct user_key_payload *upayload; 211 long ret; 212 213 upayload = rcu_dereference(key->payload.data); 214 ret = upayload->datalen; 215 216 /* we can return the data as is */ 217 if (buffer && buflen > 0) { 218 if (buflen > upayload->datalen) 219 buflen = upayload->datalen; 220 221 if (copy_to_user(buffer, upayload->data, buflen) != 0) 222 ret = -EFAULT; 223 } 224 225 return ret; 226 227 } /* end user_read() */ 228 229 EXPORT_SYMBOL_GPL(user_read); 230