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