1 /* Request key authorisation token key definition. 2 * 3 * Copyright (C) 2005 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 * See Documentation/security/keys-request-key.txt 12 */ 13 14 #include <linux/module.h> 15 #include <linux/sched.h> 16 #include <linux/err.h> 17 #include <linux/seq_file.h> 18 #include <linux/slab.h> 19 #include <asm/uaccess.h> 20 #include "internal.h" 21 22 static int request_key_auth_instantiate(struct key *, const void *, size_t); 23 static void request_key_auth_describe(const struct key *, struct seq_file *); 24 static void request_key_auth_revoke(struct key *); 25 static void request_key_auth_destroy(struct key *); 26 static long request_key_auth_read(const struct key *, char __user *, size_t); 27 28 /* 29 * The request-key authorisation key type definition. 30 */ 31 struct key_type key_type_request_key_auth = { 32 .name = ".request_key_auth", 33 .def_datalen = sizeof(struct request_key_auth), 34 .instantiate = request_key_auth_instantiate, 35 .describe = request_key_auth_describe, 36 .revoke = request_key_auth_revoke, 37 .destroy = request_key_auth_destroy, 38 .read = request_key_auth_read, 39 }; 40 41 /* 42 * Instantiate a request-key authorisation key. 43 */ 44 static int request_key_auth_instantiate(struct key *key, 45 const void *data, 46 size_t datalen) 47 { 48 key->payload.data = (struct request_key_auth *) data; 49 return 0; 50 } 51 52 /* 53 * Describe an authorisation token. 54 */ 55 static void request_key_auth_describe(const struct key *key, 56 struct seq_file *m) 57 { 58 struct request_key_auth *rka = key->payload.data; 59 60 seq_puts(m, "key:"); 61 seq_puts(m, key->description); 62 if (key_is_instantiated(key)) 63 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); 64 } 65 66 /* 67 * Read the callout_info data (retrieves the callout information). 68 * - the key's semaphore is read-locked 69 */ 70 static long request_key_auth_read(const struct key *key, 71 char __user *buffer, size_t buflen) 72 { 73 struct request_key_auth *rka = key->payload.data; 74 size_t datalen; 75 long ret; 76 77 datalen = rka->callout_len; 78 ret = datalen; 79 80 /* we can return the data as is */ 81 if (buffer && buflen > 0) { 82 if (buflen > datalen) 83 buflen = datalen; 84 85 if (copy_to_user(buffer, rka->callout_info, buflen) != 0) 86 ret = -EFAULT; 87 } 88 89 return ret; 90 } 91 92 /* 93 * Handle revocation of an authorisation token key. 94 * 95 * Called with the key sem write-locked. 96 */ 97 static void request_key_auth_revoke(struct key *key) 98 { 99 struct request_key_auth *rka = key->payload.data; 100 101 kenter("{%d}", key->serial); 102 103 if (rka->cred) { 104 put_cred(rka->cred); 105 rka->cred = NULL; 106 } 107 } 108 109 /* 110 * Destroy an instantiation authorisation token key. 111 */ 112 static void request_key_auth_destroy(struct key *key) 113 { 114 struct request_key_auth *rka = key->payload.data; 115 116 kenter("{%d}", key->serial); 117 118 if (rka->cred) { 119 put_cred(rka->cred); 120 rka->cred = NULL; 121 } 122 123 key_put(rka->target_key); 124 key_put(rka->dest_keyring); 125 kfree(rka->callout_info); 126 kfree(rka); 127 } 128 129 /* 130 * Create an authorisation token for /sbin/request-key or whoever to gain 131 * access to the caller's security data. 132 */ 133 struct key *request_key_auth_new(struct key *target, const void *callout_info, 134 size_t callout_len, struct key *dest_keyring) 135 { 136 struct request_key_auth *rka, *irka; 137 const struct cred *cred = current->cred; 138 struct key *authkey = NULL; 139 char desc[20]; 140 int ret; 141 142 kenter("%d,", target->serial); 143 144 /* allocate a auth record */ 145 rka = kmalloc(sizeof(*rka), GFP_KERNEL); 146 if (!rka) { 147 kleave(" = -ENOMEM"); 148 return ERR_PTR(-ENOMEM); 149 } 150 rka->callout_info = kmalloc(callout_len, GFP_KERNEL); 151 if (!rka->callout_info) { 152 kleave(" = -ENOMEM"); 153 kfree(rka); 154 return ERR_PTR(-ENOMEM); 155 } 156 157 /* see if the calling process is already servicing the key request of 158 * another process */ 159 if (cred->request_key_auth) { 160 /* it is - use that instantiation context here too */ 161 down_read(&cred->request_key_auth->sem); 162 163 /* if the auth key has been revoked, then the key we're 164 * servicing is already instantiated */ 165 if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags)) 166 goto auth_key_revoked; 167 168 irka = cred->request_key_auth->payload.data; 169 rka->cred = get_cred(irka->cred); 170 rka->pid = irka->pid; 171 172 up_read(&cred->request_key_auth->sem); 173 } 174 else { 175 /* it isn't - use this process as the context */ 176 rka->cred = get_cred(cred); 177 rka->pid = current->pid; 178 } 179 180 rka->target_key = key_get(target); 181 rka->dest_keyring = key_get(dest_keyring); 182 memcpy(rka->callout_info, callout_info, callout_len); 183 rka->callout_len = callout_len; 184 185 /* allocate the auth key */ 186 sprintf(desc, "%x", target->serial); 187 188 authkey = key_alloc(&key_type_request_key_auth, desc, 189 cred->fsuid, cred->fsgid, cred, 190 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | 191 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA); 192 if (IS_ERR(authkey)) { 193 ret = PTR_ERR(authkey); 194 goto error_alloc; 195 } 196 197 /* construct the auth key */ 198 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); 199 if (ret < 0) 200 goto error_inst; 201 202 kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage)); 203 return authkey; 204 205 auth_key_revoked: 206 up_read(&cred->request_key_auth->sem); 207 kfree(rka->callout_info); 208 kfree(rka); 209 kleave("= -EKEYREVOKED"); 210 return ERR_PTR(-EKEYREVOKED); 211 212 error_inst: 213 key_revoke(authkey); 214 key_put(authkey); 215 error_alloc: 216 key_put(rka->target_key); 217 key_put(rka->dest_keyring); 218 kfree(rka->callout_info); 219 kfree(rka); 220 kleave("= %d", ret); 221 return ERR_PTR(ret); 222 } 223 224 /* 225 * See if an authorisation key is associated with a particular key. 226 */ 227 static int key_get_instantiation_authkey_match(const struct key *key, 228 const void *_id) 229 { 230 struct request_key_auth *rka = key->payload.data; 231 key_serial_t id = (key_serial_t)(unsigned long) _id; 232 233 return rka->target_key->serial == id; 234 } 235 236 /* 237 * Search the current process's keyrings for the authorisation key for 238 * instantiation of a key. 239 */ 240 struct key *key_get_instantiation_authkey(key_serial_t target_id) 241 { 242 const struct cred *cred = current_cred(); 243 struct key *authkey; 244 key_ref_t authkey_ref; 245 246 authkey_ref = search_process_keyrings( 247 &key_type_request_key_auth, 248 (void *) (unsigned long) target_id, 249 key_get_instantiation_authkey_match, 250 cred); 251 252 if (IS_ERR(authkey_ref)) { 253 authkey = ERR_CAST(authkey_ref); 254 if (authkey == ERR_PTR(-EAGAIN)) 255 authkey = ERR_PTR(-ENOKEY); 256 goto error; 257 } 258 259 authkey = key_ref_to_ptr(authkey_ref); 260 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { 261 key_put(authkey); 262 authkey = ERR_PTR(-EKEYREVOKED); 263 } 264 265 error: 266 return authkey; 267 } 268