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 static int logon_vet_description(const char *desc); 22 23 /* 24 * user defined keys take an arbitrary string as the description and an 25 * arbitrary blob of data as the payload 26 */ 27 struct key_type key_type_user = { 28 .name = "user", 29 .def_lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 30 .preparse = user_preparse, 31 .free_preparse = user_free_preparse, 32 .instantiate = generic_key_instantiate, 33 .update = user_update, 34 .match = user_match, 35 .revoke = user_revoke, 36 .destroy = user_destroy, 37 .describe = user_describe, 38 .read = user_read, 39 }; 40 41 EXPORT_SYMBOL_GPL(key_type_user); 42 43 /* 44 * This key type is essentially the same as key_type_user, but it does 45 * not define a .read op. This is suitable for storing username and 46 * password pairs in the keyring that you do not want to be readable 47 * from userspace. 48 */ 49 struct key_type key_type_logon = { 50 .name = "logon", 51 .def_lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 52 .preparse = user_preparse, 53 .free_preparse = user_free_preparse, 54 .instantiate = generic_key_instantiate, 55 .update = user_update, 56 .match = user_match, 57 .revoke = user_revoke, 58 .destroy = user_destroy, 59 .describe = user_describe, 60 .vet_description = logon_vet_description, 61 }; 62 EXPORT_SYMBOL_GPL(key_type_logon); 63 64 /* 65 * Preparse a user defined key payload 66 */ 67 int user_preparse(struct key_preparsed_payload *prep) 68 { 69 struct user_key_payload *upayload; 70 size_t datalen = prep->datalen; 71 72 if (datalen <= 0 || datalen > 32767 || !prep->data) 73 return -EINVAL; 74 75 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 76 if (!upayload) 77 return -ENOMEM; 78 79 /* attach the data */ 80 prep->quotalen = datalen; 81 prep->payload[0] = upayload; 82 upayload->datalen = datalen; 83 memcpy(upayload->data, prep->data, datalen); 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(user_preparse); 87 88 /* 89 * Free a preparse of a user defined key payload 90 */ 91 void user_free_preparse(struct key_preparsed_payload *prep) 92 { 93 kfree(prep->payload[0]); 94 } 95 EXPORT_SYMBOL_GPL(user_free_preparse); 96 97 /* 98 * update a user defined key 99 * - the key's semaphore is write-locked 100 */ 101 int user_update(struct key *key, struct key_preparsed_payload *prep) 102 { 103 struct user_key_payload *upayload, *zap; 104 size_t datalen = prep->datalen; 105 int ret; 106 107 ret = -EINVAL; 108 if (datalen <= 0 || datalen > 32767 || !prep->data) 109 goto error; 110 111 /* construct a replacement payload */ 112 ret = -ENOMEM; 113 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 114 if (!upayload) 115 goto error; 116 117 upayload->datalen = datalen; 118 memcpy(upayload->data, prep->data, datalen); 119 120 /* check the quota and attach the new data */ 121 zap = upayload; 122 123 ret = key_payload_reserve(key, datalen); 124 125 if (ret == 0) { 126 /* attach the new data, displacing the old */ 127 zap = key->payload.data; 128 rcu_assign_keypointer(key, upayload); 129 key->expiry = 0; 130 } 131 132 if (zap) 133 kfree_rcu(zap, rcu); 134 135 error: 136 return ret; 137 } 138 139 EXPORT_SYMBOL_GPL(user_update); 140 141 /* 142 * match users on their name 143 */ 144 int user_match(const struct key *key, const void *description) 145 { 146 return strcmp(key->description, description) == 0; 147 } 148 149 EXPORT_SYMBOL_GPL(user_match); 150 151 /* 152 * dispose of the links from a revoked keyring 153 * - called with the key sem write-locked 154 */ 155 void user_revoke(struct key *key) 156 { 157 struct user_key_payload *upayload = key->payload.data; 158 159 /* clear the quota */ 160 key_payload_reserve(key, 0); 161 162 if (upayload) { 163 rcu_assign_keypointer(key, NULL); 164 kfree_rcu(upayload, rcu); 165 } 166 } 167 168 EXPORT_SYMBOL(user_revoke); 169 170 /* 171 * dispose of the data dangling from the corpse of a user key 172 */ 173 void user_destroy(struct key *key) 174 { 175 struct user_key_payload *upayload = key->payload.data; 176 177 kfree(upayload); 178 } 179 180 EXPORT_SYMBOL_GPL(user_destroy); 181 182 /* 183 * describe the user key 184 */ 185 void user_describe(const struct key *key, struct seq_file *m) 186 { 187 seq_puts(m, key->description); 188 if (key_is_instantiated(key)) 189 seq_printf(m, ": %u", key->datalen); 190 } 191 192 EXPORT_SYMBOL_GPL(user_describe); 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(key); 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 } 217 218 EXPORT_SYMBOL_GPL(user_read); 219 220 /* Vet the description for a "logon" key */ 221 static int logon_vet_description(const char *desc) 222 { 223 char *p; 224 225 /* require a "qualified" description string */ 226 p = strchr(desc, ':'); 227 if (!p) 228 return -EINVAL; 229 230 /* also reject description with ':' as first char */ 231 if (p == desc) 232 return -EINVAL; 233 234 return 0; 235 } 236