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 .update = user_update, 30 .match = user_match, 31 .revoke = user_revoke, 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 * dispose of the old data from an updated user defined key 77 */ 78 static void user_update_rcu_disposal(struct rcu_head *rcu) 79 { 80 struct user_key_payload *upayload; 81 82 upayload = container_of(rcu, struct user_key_payload, rcu); 83 84 kfree(upayload); 85 86 } /* end user_update_rcu_disposal() */ 87 88 /*****************************************************************************/ 89 /* 90 * update a user defined key 91 * - the key's semaphore is write-locked 92 */ 93 int user_update(struct key *key, const void *data, size_t datalen) 94 { 95 struct user_key_payload *upayload, *zap; 96 int ret; 97 98 ret = -EINVAL; 99 if (datalen <= 0 || datalen > 32767 || !data) 100 goto error; 101 102 /* construct a replacement payload */ 103 ret = -ENOMEM; 104 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 105 if (!upayload) 106 goto error; 107 108 upayload->datalen = datalen; 109 memcpy(upayload->data, data, datalen); 110 111 /* check the quota and attach the new data */ 112 zap = upayload; 113 114 ret = key_payload_reserve(key, datalen); 115 116 if (ret == 0) { 117 /* attach the new data, displacing the old */ 118 zap = key->payload.data; 119 rcu_assign_pointer(key->payload.data, upayload); 120 key->expiry = 0; 121 } 122 123 call_rcu(&zap->rcu, user_update_rcu_disposal); 124 125 error: 126 return ret; 127 128 } /* end user_update() */ 129 130 EXPORT_SYMBOL_GPL(user_update); 131 132 /*****************************************************************************/ 133 /* 134 * match users on their name 135 */ 136 int user_match(const struct key *key, const void *description) 137 { 138 return strcmp(key->description, description) == 0; 139 140 } /* end user_match() */ 141 142 EXPORT_SYMBOL_GPL(user_match); 143 144 /*****************************************************************************/ 145 /* 146 * dispose of the links from a revoked keyring 147 * - called with the key sem write-locked 148 */ 149 void user_revoke(struct key *key) 150 { 151 struct user_key_payload *upayload = key->payload.data; 152 153 /* clear the quota */ 154 key_payload_reserve(key, 0); 155 156 if (upayload) { 157 rcu_assign_pointer(key->payload.data, NULL); 158 call_rcu(&upayload->rcu, user_update_rcu_disposal); 159 } 160 161 } /* end user_revoke() */ 162 163 EXPORT_SYMBOL(user_revoke); 164 165 /*****************************************************************************/ 166 /* 167 * dispose of the data dangling from the corpse of a user key 168 */ 169 void user_destroy(struct key *key) 170 { 171 struct user_key_payload *upayload = key->payload.data; 172 173 kfree(upayload); 174 175 } /* end user_destroy() */ 176 177 EXPORT_SYMBOL_GPL(user_destroy); 178 179 /*****************************************************************************/ 180 /* 181 * describe the user key 182 */ 183 void user_describe(const struct key *key, struct seq_file *m) 184 { 185 seq_puts(m, key->description); 186 187 seq_printf(m, ": %u", key->datalen); 188 189 } /* end user_describe() */ 190 191 EXPORT_SYMBOL_GPL(user_describe); 192 193 /*****************************************************************************/ 194 /* 195 * read the key data 196 * - the key's semaphore is read-locked 197 */ 198 long user_read(const struct key *key, char __user *buffer, size_t buflen) 199 { 200 struct user_key_payload *upayload; 201 long ret; 202 203 upayload = rcu_dereference(key->payload.data); 204 ret = upayload->datalen; 205 206 /* we can return the data as is */ 207 if (buffer && buflen > 0) { 208 if (buflen > upayload->datalen) 209 buflen = upayload->datalen; 210 211 if (copy_to_user(buffer, upayload->data, buflen) != 0) 212 ret = -EFAULT; 213 } 214 215 return ret; 216 217 } /* end user_read() */ 218 219 EXPORT_SYMBOL_GPL(user_read); 220