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 .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 EXPORT_SYMBOL_GPL(user_instantiate); 71 72 /*****************************************************************************/ 73 /* 74 * dispose of the old data from an updated user defined key 75 */ 76 static void user_update_rcu_disposal(struct rcu_head *rcu) 77 { 78 struct user_key_payload *upayload; 79 80 upayload = container_of(rcu, struct user_key_payload, rcu); 81 82 kfree(upayload); 83 84 } /* end user_update_rcu_disposal() */ 85 86 /*****************************************************************************/ 87 /* 88 * update a user defined key 89 * - the key's semaphore is write-locked 90 */ 91 int user_update(struct key *key, const void *data, size_t datalen) 92 { 93 struct user_key_payload *upayload, *zap; 94 int ret; 95 96 ret = -EINVAL; 97 if (datalen <= 0 || datalen > 32767 || !data) 98 goto error; 99 100 /* construct a replacement payload */ 101 ret = -ENOMEM; 102 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 103 if (!upayload) 104 goto error; 105 106 upayload->datalen = datalen; 107 memcpy(upayload->data, data, datalen); 108 109 /* check the quota and attach the new data */ 110 zap = upayload; 111 112 ret = key_payload_reserve(key, datalen); 113 114 if (ret == 0) { 115 /* attach the new data, displacing the old */ 116 zap = key->payload.data; 117 rcu_assign_pointer(key->payload.data, upayload); 118 key->expiry = 0; 119 } 120 121 call_rcu(&zap->rcu, user_update_rcu_disposal); 122 123 error: 124 return ret; 125 126 } /* end user_update() */ 127 128 EXPORT_SYMBOL_GPL(user_update); 129 130 /*****************************************************************************/ 131 /* 132 * match users on their name 133 */ 134 int user_match(const struct key *key, const void *description) 135 { 136 return strcmp(key->description, description) == 0; 137 138 } /* end user_match() */ 139 140 EXPORT_SYMBOL_GPL(user_match); 141 142 /*****************************************************************************/ 143 /* 144 * dispose of the data dangling from the corpse of a user 145 */ 146 void user_destroy(struct key *key) 147 { 148 struct user_key_payload *upayload = key->payload.data; 149 150 kfree(upayload); 151 152 } /* end user_destroy() */ 153 154 EXPORT_SYMBOL_GPL(user_destroy); 155 156 /*****************************************************************************/ 157 /* 158 * describe the user key 159 */ 160 void user_describe(const struct key *key, struct seq_file *m) 161 { 162 seq_puts(m, key->description); 163 164 seq_printf(m, ": %u", key->datalen); 165 166 } /* end user_describe() */ 167 168 EXPORT_SYMBOL_GPL(user_describe); 169 170 /*****************************************************************************/ 171 /* 172 * read the key data 173 * - the key's semaphore is read-locked 174 */ 175 long user_read(const struct key *key, char __user *buffer, size_t buflen) 176 { 177 struct user_key_payload *upayload; 178 long ret; 179 180 upayload = rcu_dereference(key->payload.data); 181 ret = upayload->datalen; 182 183 /* we can return the data as is */ 184 if (buffer && buflen > 0) { 185 if (buflen > upayload->datalen) 186 buflen = upayload->datalen; 187 188 if (copy_to_user(buffer, upayload->data, buflen) != 0) 189 ret = -EFAULT; 190 } 191 192 return ret; 193 194 } /* end user_read() */ 195 196 EXPORT_SYMBOL_GPL(user_read); 197