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 /* 40 * instantiate a user defined key 41 */ 42 int user_instantiate(struct key *key, const void *data, size_t datalen) 43 { 44 struct user_key_payload *upayload; 45 int ret; 46 47 ret = -EINVAL; 48 if (datalen <= 0 || datalen > 32767 || !data) 49 goto error; 50 51 ret = key_payload_reserve(key, datalen); 52 if (ret < 0) 53 goto error; 54 55 ret = -ENOMEM; 56 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 57 if (!upayload) 58 goto error; 59 60 /* attach the data */ 61 upayload->datalen = datalen; 62 memcpy(upayload->data, data, datalen); 63 rcu_assign_pointer(key->payload.data, upayload); 64 ret = 0; 65 66 error: 67 return ret; 68 69 } /* end user_instantiate() */ 70 71 EXPORT_SYMBOL_GPL(user_instantiate); 72 73 /*****************************************************************************/ 74 /* 75 * dispose of the old data from an updated user defined key 76 */ 77 static void user_update_rcu_disposal(struct rcu_head *rcu) 78 { 79 struct user_key_payload *upayload; 80 81 upayload = container_of(rcu, struct user_key_payload, rcu); 82 83 kfree(upayload); 84 85 } /* end user_update_rcu_disposal() */ 86 87 /*****************************************************************************/ 88 /* 89 * update a user defined key 90 * - the key's semaphore is write-locked 91 */ 92 int user_update(struct key *key, const void *data, size_t datalen) 93 { 94 struct user_key_payload *upayload, *zap; 95 int ret; 96 97 ret = -EINVAL; 98 if (datalen <= 0 || datalen > 32767 || !data) 99 goto error; 100 101 /* construct a replacement payload */ 102 ret = -ENOMEM; 103 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 104 if (!upayload) 105 goto error; 106 107 upayload->datalen = datalen; 108 memcpy(upayload->data, data, datalen); 109 110 /* check the quota and attach the new data */ 111 zap = upayload; 112 113 ret = key_payload_reserve(key, datalen); 114 115 if (ret == 0) { 116 /* attach the new data, displacing the old */ 117 zap = key->payload.data; 118 rcu_assign_pointer(key->payload.data, upayload); 119 key->expiry = 0; 120 } 121 122 call_rcu(&zap->rcu, user_update_rcu_disposal); 123 124 error: 125 return ret; 126 127 } /* end user_update() */ 128 129 EXPORT_SYMBOL_GPL(user_update); 130 131 /*****************************************************************************/ 132 /* 133 * match users on their name 134 */ 135 int user_match(const struct key *key, const void *description) 136 { 137 return strcmp(key->description, description) == 0; 138 139 } /* end user_match() */ 140 141 EXPORT_SYMBOL_GPL(user_match); 142 143 /*****************************************************************************/ 144 /* 145 * dispose of the links from a revoked keyring 146 * - called with the key sem write-locked 147 */ 148 void user_revoke(struct key *key) 149 { 150 struct user_key_payload *upayload = key->payload.data; 151 152 /* clear the quota */ 153 key_payload_reserve(key, 0); 154 155 if (upayload) { 156 rcu_assign_pointer(key->payload.data, NULL); 157 call_rcu(&upayload->rcu, user_update_rcu_disposal); 158 } 159 160 } /* end user_revoke() */ 161 162 EXPORT_SYMBOL(user_revoke); 163 164 /*****************************************************************************/ 165 /* 166 * dispose of the data dangling from the corpse of a user key 167 */ 168 void user_destroy(struct key *key) 169 { 170 struct user_key_payload *upayload = key->payload.data; 171 172 kfree(upayload); 173 174 } /* end user_destroy() */ 175 176 EXPORT_SYMBOL_GPL(user_destroy); 177 178 /*****************************************************************************/ 179 /* 180 * describe the user key 181 */ 182 void user_describe(const struct key *key, struct seq_file *m) 183 { 184 seq_puts(m, key->description); 185 186 seq_printf(m, ": %u", key->datalen); 187 188 } /* end user_describe() */ 189 190 EXPORT_SYMBOL_GPL(user_describe); 191 192 /*****************************************************************************/ 193 /* 194 * read the key data 195 * - the key's semaphore is read-locked 196 */ 197 long user_read(const struct key *key, char __user *buffer, size_t buflen) 198 { 199 struct user_key_payload *upayload; 200 long ret; 201 202 upayload = rcu_dereference(key->payload.data); 203 ret = upayload->datalen; 204 205 /* we can return the data as is */ 206 if (buffer && buflen > 0) { 207 if (buflen > upayload->datalen) 208 buflen = upayload->datalen; 209 210 if (copy_to_user(buffer, upayload->data, buflen) != 0) 211 ret = -EFAULT; 212 } 213 214 return ret; 215 216 } /* end user_read() */ 217 218 EXPORT_SYMBOL_GPL(user_read); 219