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/export.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 <linux/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 kzfree(prep->payload.data[0]); 90 } 91 EXPORT_SYMBOL_GPL(user_free_preparse); 92 93 static void user_free_payload_rcu(struct rcu_head *head) 94 { 95 struct user_key_payload *payload; 96 97 payload = container_of(head, struct user_key_payload, rcu); 98 kzfree(payload); 99 } 100 101 /* 102 * update a user defined key 103 * - the key's semaphore is write-locked 104 */ 105 int user_update(struct key *key, struct key_preparsed_payload *prep) 106 { 107 struct user_key_payload *zap = NULL; 108 int ret; 109 110 /* check the quota and attach the new data */ 111 ret = key_payload_reserve(key, prep->datalen); 112 if (ret < 0) 113 return ret; 114 115 /* attach the new data, displacing the old */ 116 key->expiry = prep->expiry; 117 if (key_is_positive(key)) 118 zap = dereference_key_locked(key); 119 rcu_assign_keypointer(key, prep->payload.data[0]); 120 prep->payload.data[0] = NULL; 121 122 if (zap) 123 call_rcu(&zap->rcu, user_free_payload_rcu); 124 return ret; 125 } 126 EXPORT_SYMBOL_GPL(user_update); 127 128 /* 129 * dispose of the links from a revoked keyring 130 * - called with the key sem write-locked 131 */ 132 void user_revoke(struct key *key) 133 { 134 struct user_key_payload *upayload = user_key_payload_locked(key); 135 136 /* clear the quota */ 137 key_payload_reserve(key, 0); 138 139 if (upayload) { 140 rcu_assign_keypointer(key, NULL); 141 call_rcu(&upayload->rcu, user_free_payload_rcu); 142 } 143 } 144 145 EXPORT_SYMBOL(user_revoke); 146 147 /* 148 * dispose of the data dangling from the corpse of a user key 149 */ 150 void user_destroy(struct key *key) 151 { 152 struct user_key_payload *upayload = key->payload.data[0]; 153 154 kzfree(upayload); 155 } 156 157 EXPORT_SYMBOL_GPL(user_destroy); 158 159 /* 160 * describe the user key 161 */ 162 void user_describe(const struct key *key, struct seq_file *m) 163 { 164 seq_puts(m, key->description); 165 if (key_is_positive(key)) 166 seq_printf(m, ": %u", key->datalen); 167 } 168 169 EXPORT_SYMBOL_GPL(user_describe); 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 const struct user_key_payload *upayload; 178 long ret; 179 180 upayload = user_key_payload_locked(key); 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 } 194 195 EXPORT_SYMBOL_GPL(user_read); 196 197 /* Vet the description for a "logon" key */ 198 static int logon_vet_description(const char *desc) 199 { 200 char *p; 201 202 /* require a "qualified" description string */ 203 p = strchr(desc, ':'); 204 if (!p) 205 return -EINVAL; 206 207 /* also reject description with ':' as first char */ 208 if (p == desc) 209 return -EINVAL; 210 211 return 0; 212 } 213