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 *zap = NULL; 100 int ret; 101 102 /* check the quota and attach the new data */ 103 ret = key_payload_reserve(key, prep->datalen); 104 if (ret < 0) 105 return ret; 106 107 /* attach the new data, displacing the old */ 108 key->expiry = prep->expiry; 109 if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags)) 110 zap = rcu_dereference_key(key); 111 rcu_assign_keypointer(key, prep->payload.data[0]); 112 prep->payload.data[0] = NULL; 113 114 if (zap) 115 kfree_rcu(zap, rcu); 116 return ret; 117 } 118 EXPORT_SYMBOL_GPL(user_update); 119 120 /* 121 * dispose of the links from a revoked keyring 122 * - called with the key sem write-locked 123 */ 124 void user_revoke(struct key *key) 125 { 126 struct user_key_payload *upayload = key->payload.data[0]; 127 128 /* clear the quota */ 129 key_payload_reserve(key, 0); 130 131 if (upayload) { 132 rcu_assign_keypointer(key, NULL); 133 kfree_rcu(upayload, rcu); 134 } 135 } 136 137 EXPORT_SYMBOL(user_revoke); 138 139 /* 140 * dispose of the data dangling from the corpse of a user key 141 */ 142 void user_destroy(struct key *key) 143 { 144 struct user_key_payload *upayload = key->payload.data[0]; 145 146 kfree(upayload); 147 } 148 149 EXPORT_SYMBOL_GPL(user_destroy); 150 151 /* 152 * describe the user key 153 */ 154 void user_describe(const struct key *key, struct seq_file *m) 155 { 156 seq_puts(m, key->description); 157 if (key_is_instantiated(key)) 158 seq_printf(m, ": %u", key->datalen); 159 } 160 161 EXPORT_SYMBOL_GPL(user_describe); 162 163 /* 164 * read the key data 165 * - the key's semaphore is read-locked 166 */ 167 long user_read(const struct key *key, char __user *buffer, size_t buflen) 168 { 169 const struct user_key_payload *upayload; 170 long ret; 171 172 upayload = user_key_payload(key); 173 ret = upayload->datalen; 174 175 /* we can return the data as is */ 176 if (buffer && buflen > 0) { 177 if (buflen > upayload->datalen) 178 buflen = upayload->datalen; 179 180 if (copy_to_user(buffer, upayload->data, buflen) != 0) 181 ret = -EFAULT; 182 } 183 184 return ret; 185 } 186 187 EXPORT_SYMBOL_GPL(user_read); 188 189 /* Vet the description for a "logon" key */ 190 static int logon_vet_description(const char *desc) 191 { 192 char *p; 193 194 /* require a "qualified" description string */ 195 p = strchr(desc, ':'); 196 if (!p) 197 return -EINVAL; 198 199 /* also reject description with ':' as first char */ 200 if (p == desc) 201 return -EINVAL; 202 203 return 0; 204 } 205