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 .preparse = user_preparse, 30 .free_preparse = user_free_preparse, 31 .instantiate = generic_key_instantiate, 32 .update = user_update, 33 .revoke = user_revoke, 34 .destroy = user_destroy, 35 .describe = user_describe, 36 .read = user_read, 37 }; 38 39 EXPORT_SYMBOL_GPL(key_type_user); 40 41 /* 42 * This key type is essentially the same as key_type_user, but it does 43 * not define a .read op. This is suitable for storing username and 44 * password pairs in the keyring that you do not want to be readable 45 * from userspace. 46 */ 47 struct key_type key_type_logon = { 48 .name = "logon", 49 .preparse = user_preparse, 50 .free_preparse = user_free_preparse, 51 .instantiate = generic_key_instantiate, 52 .update = user_update, 53 .revoke = user_revoke, 54 .destroy = user_destroy, 55 .describe = user_describe, 56 .vet_description = logon_vet_description, 57 }; 58 EXPORT_SYMBOL_GPL(key_type_logon); 59 60 /* 61 * Preparse a user defined key payload 62 */ 63 int user_preparse(struct key_preparsed_payload *prep) 64 { 65 struct user_key_payload *upayload; 66 size_t datalen = prep->datalen; 67 68 if (datalen <= 0 || datalen > 32767 || !prep->data) 69 return -EINVAL; 70 71 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 72 if (!upayload) 73 return -ENOMEM; 74 75 /* attach the data */ 76 prep->quotalen = datalen; 77 prep->payload.data[0] = upayload; 78 upayload->datalen = datalen; 79 memcpy(upayload->data, prep->data, datalen); 80 return 0; 81 } 82 EXPORT_SYMBOL_GPL(user_preparse); 83 84 /* 85 * Free a preparse of a user defined key payload 86 */ 87 void user_free_preparse(struct key_preparsed_payload *prep) 88 { 89 kfree(prep->payload.data[0]); 90 } 91 EXPORT_SYMBOL_GPL(user_free_preparse); 92 93 /* 94 * update a user defined key 95 * - the key's semaphore is write-locked 96 */ 97 int user_update(struct key *key, struct key_preparsed_payload *prep) 98 { 99 struct user_key_payload *upayload, *zap; 100 size_t datalen = prep->datalen; 101 int ret; 102 103 ret = -EINVAL; 104 if (datalen <= 0 || datalen > 32767 || !prep->data) 105 goto error; 106 107 /* construct a replacement payload */ 108 ret = -ENOMEM; 109 upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL); 110 if (!upayload) 111 goto error; 112 113 upayload->datalen = datalen; 114 memcpy(upayload->data, prep->data, datalen); 115 116 /* check the quota and attach the new data */ 117 zap = upayload; 118 119 ret = key_payload_reserve(key, datalen); 120 121 if (ret == 0) { 122 /* attach the new data, displacing the old */ 123 if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags)) 124 zap = key->payload.data[0]; 125 else 126 zap = NULL; 127 rcu_assign_keypointer(key, upayload); 128 key->expiry = 0; 129 } 130 131 if (zap) 132 kfree_rcu(zap, rcu); 133 134 error: 135 return ret; 136 } 137 138 EXPORT_SYMBOL_GPL(user_update); 139 140 /* 141 * dispose of the links from a revoked keyring 142 * - called with the key sem write-locked 143 */ 144 void user_revoke(struct key *key) 145 { 146 struct user_key_payload *upayload = key->payload.data[0]; 147 148 /* clear the quota */ 149 key_payload_reserve(key, 0); 150 151 if (upayload) { 152 rcu_assign_keypointer(key, NULL); 153 kfree_rcu(upayload, rcu); 154 } 155 } 156 157 EXPORT_SYMBOL(user_revoke); 158 159 /* 160 * dispose of the data dangling from the corpse of a user key 161 */ 162 void user_destroy(struct key *key) 163 { 164 struct user_key_payload *upayload = key->payload.data[0]; 165 166 kfree(upayload); 167 } 168 169 EXPORT_SYMBOL_GPL(user_destroy); 170 171 /* 172 * describe the user key 173 */ 174 void user_describe(const struct key *key, struct seq_file *m) 175 { 176 seq_puts(m, key->description); 177 if (key_is_instantiated(key)) 178 seq_printf(m, ": %u", key->datalen); 179 } 180 181 EXPORT_SYMBOL_GPL(user_describe); 182 183 /* 184 * read the key data 185 * - the key's semaphore is read-locked 186 */ 187 long user_read(const struct key *key, char __user *buffer, size_t buflen) 188 { 189 const struct user_key_payload *upayload; 190 long ret; 191 192 upayload = user_key_payload(key); 193 ret = upayload->datalen; 194 195 /* we can return the data as is */ 196 if (buffer && buflen > 0) { 197 if (buflen > upayload->datalen) 198 buflen = upayload->datalen; 199 200 if (copy_to_user(buffer, upayload->data, buflen) != 0) 201 ret = -EFAULT; 202 } 203 204 return ret; 205 } 206 207 EXPORT_SYMBOL_GPL(user_read); 208 209 /* Vet the description for a "logon" key */ 210 static int logon_vet_description(const char *desc) 211 { 212 char *p; 213 214 /* require a "qualified" description string */ 215 p = strchr(desc, ':'); 216 if (!p) 217 return -EINVAL; 218 219 /* also reject description with ':' as first char */ 220 if (p == desc) 221 return -EINVAL; 222 223 return 0; 224 } 225