| 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 | #include <keys/user-type.h> |
| 22 | |
| 23 | static int request_key_auth_preparse(struct key_preparsed_payload *); |
| 24 | static void request_key_auth_free_preparse(struct key_preparsed_payload *); |
| 25 | static int request_key_auth_instantiate(struct key *, |
| 26 | struct key_preparsed_payload *); |
| 27 | static void request_key_auth_describe(const struct key *, struct seq_file *); |
| 28 | static void request_key_auth_revoke(struct key *); |
| 29 | static void request_key_auth_destroy(struct key *); |
| 30 | static long request_key_auth_read(const struct key *, char __user *, size_t); |
| 31 | |
| 32 | /* |
| 33 | * The request-key authorisation key type definition. |
| 34 | */ |
| 35 | struct key_type key_type_request_key_auth = { |
| 36 | .name = ".request_key_auth", |
| 37 | .def_datalen = sizeof(struct request_key_auth), |
| 38 | .preparse = request_key_auth_preparse, |
| 39 | .free_preparse = request_key_auth_free_preparse, |
| 40 | .instantiate = request_key_auth_instantiate, |
| 41 | .describe = request_key_auth_describe, |
| 42 | .revoke = request_key_auth_revoke, |
| 43 | .destroy = request_key_auth_destroy, |
| 44 | .read = request_key_auth_read, |
| 45 | }; |
| 46 | |
| 47 | static int request_key_auth_preparse(struct key_preparsed_payload *prep) |
| 48 | { |
| 49 | return 0; |
| 50 | } |
| 51 | |
| 52 | static void request_key_auth_free_preparse(struct key_preparsed_payload *prep) |
| 53 | { |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Instantiate a request-key authorisation key. |
| 58 | */ |
| 59 | static int request_key_auth_instantiate(struct key *key, |
| 60 | struct key_preparsed_payload *prep) |
| 61 | { |
| 62 | key->payload.data = (struct request_key_auth *)prep->data; |
| 63 | return 0; |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Describe an authorisation token. |
| 68 | */ |
| 69 | static void request_key_auth_describe(const struct key *key, |
| 70 | struct seq_file *m) |
| 71 | { |
| 72 | struct request_key_auth *rka = key->payload.data; |
| 73 | |
| 74 | seq_puts(m, "key:"); |
| 75 | seq_puts(m, key->description); |
| 76 | if (key_is_instantiated(key)) |
| 77 | seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Read the callout_info data (retrieves the callout information). |
| 82 | * - the key's semaphore is read-locked |
| 83 | */ |
| 84 | static long request_key_auth_read(const struct key *key, |
| 85 | char __user *buffer, size_t buflen) |
| 86 | { |
| 87 | struct request_key_auth *rka = key->payload.data; |
| 88 | size_t datalen; |
| 89 | long ret; |
| 90 | |
| 91 | datalen = rka->callout_len; |
| 92 | ret = datalen; |
| 93 | |
| 94 | /* we can return the data as is */ |
| 95 | if (buffer && buflen > 0) { |
| 96 | if (buflen > datalen) |
| 97 | buflen = datalen; |
| 98 | |
| 99 | if (copy_to_user(buffer, rka->callout_info, buflen) != 0) |
| 100 | ret = -EFAULT; |
| 101 | } |
| 102 | |
| 103 | return ret; |
| 104 | } |
| 105 | |
| 106 | /* |
| 107 | * Handle revocation of an authorisation token key. |
| 108 | * |
| 109 | * Called with the key sem write-locked. |
| 110 | */ |
| 111 | static void request_key_auth_revoke(struct key *key) |
| 112 | { |
| 113 | struct request_key_auth *rka = key->payload.data; |
| 114 | |
| 115 | kenter("{%d}", key->serial); |
| 116 | |
| 117 | if (rka->cred) { |
| 118 | put_cred(rka->cred); |
| 119 | rka->cred = NULL; |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | /* |
| 124 | * Destroy an instantiation authorisation token key. |
| 125 | */ |
| 126 | static void request_key_auth_destroy(struct key *key) |
| 127 | { |
| 128 | struct request_key_auth *rka = key->payload.data; |
| 129 | |
| 130 | kenter("{%d}", key->serial); |
| 131 | |
| 132 | if (rka->cred) { |
| 133 | put_cred(rka->cred); |
| 134 | rka->cred = NULL; |
| 135 | } |
| 136 | |
| 137 | key_put(rka->target_key); |
| 138 | key_put(rka->dest_keyring); |
| 139 | kfree(rka->callout_info); |
| 140 | kfree(rka); |
| 141 | } |
| 142 | |
| 143 | /* |
| 144 | * Create an authorisation token for /sbin/request-key or whoever to gain |
| 145 | * access to the caller's security data. |
| 146 | */ |
| 147 | struct key *request_key_auth_new(struct key *target, const void *callout_info, |
| 148 | size_t callout_len, struct key *dest_keyring) |
| 149 | { |
| 150 | struct request_key_auth *rka, *irka; |
| 151 | const struct cred *cred = current->cred; |
| 152 | struct key *authkey = NULL; |
| 153 | char desc[20]; |
| 154 | int ret; |
| 155 | |
| 156 | kenter("%d,", target->serial); |
| 157 | |
| 158 | /* allocate a auth record */ |
| 159 | rka = kmalloc(sizeof(*rka), GFP_KERNEL); |
| 160 | if (!rka) { |
| 161 | kleave(" = -ENOMEM"); |
| 162 | return ERR_PTR(-ENOMEM); |
| 163 | } |
| 164 | rka->callout_info = kmalloc(callout_len, GFP_KERNEL); |
| 165 | if (!rka->callout_info) { |
| 166 | kleave(" = -ENOMEM"); |
| 167 | kfree(rka); |
| 168 | return ERR_PTR(-ENOMEM); |
| 169 | } |
| 170 | |
| 171 | /* see if the calling process is already servicing the key request of |
| 172 | * another process */ |
| 173 | if (cred->request_key_auth) { |
| 174 | /* it is - use that instantiation context here too */ |
| 175 | down_read(&cred->request_key_auth->sem); |
| 176 | |
| 177 | /* if the auth key has been revoked, then the key we're |
| 178 | * servicing is already instantiated */ |
| 179 | if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags)) |
| 180 | goto auth_key_revoked; |
| 181 | |
| 182 | irka = cred->request_key_auth->payload.data; |
| 183 | rka->cred = get_cred(irka->cred); |
| 184 | rka->pid = irka->pid; |
| 185 | |
| 186 | up_read(&cred->request_key_auth->sem); |
| 187 | } |
| 188 | else { |
| 189 | /* it isn't - use this process as the context */ |
| 190 | rka->cred = get_cred(cred); |
| 191 | rka->pid = current->pid; |
| 192 | } |
| 193 | |
| 194 | rka->target_key = key_get(target); |
| 195 | rka->dest_keyring = key_get(dest_keyring); |
| 196 | memcpy(rka->callout_info, callout_info, callout_len); |
| 197 | rka->callout_len = callout_len; |
| 198 | |
| 199 | /* allocate the auth key */ |
| 200 | sprintf(desc, "%x", target->serial); |
| 201 | |
| 202 | authkey = key_alloc(&key_type_request_key_auth, desc, |
| 203 | cred->fsuid, cred->fsgid, cred, |
| 204 | KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | |
| 205 | KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA); |
| 206 | if (IS_ERR(authkey)) { |
| 207 | ret = PTR_ERR(authkey); |
| 208 | goto error_alloc; |
| 209 | } |
| 210 | |
| 211 | /* construct the auth key */ |
| 212 | ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); |
| 213 | if (ret < 0) |
| 214 | goto error_inst; |
| 215 | |
| 216 | kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage)); |
| 217 | return authkey; |
| 218 | |
| 219 | auth_key_revoked: |
| 220 | up_read(&cred->request_key_auth->sem); |
| 221 | kfree(rka->callout_info); |
| 222 | kfree(rka); |
| 223 | kleave("= -EKEYREVOKED"); |
| 224 | return ERR_PTR(-EKEYREVOKED); |
| 225 | |
| 226 | error_inst: |
| 227 | key_revoke(authkey); |
| 228 | key_put(authkey); |
| 229 | error_alloc: |
| 230 | key_put(rka->target_key); |
| 231 | key_put(rka->dest_keyring); |
| 232 | kfree(rka->callout_info); |
| 233 | kfree(rka); |
| 234 | kleave("= %d", ret); |
| 235 | return ERR_PTR(ret); |
| 236 | } |
| 237 | |
| 238 | /* |
| 239 | * Search the current process's keyrings for the authorisation key for |
| 240 | * instantiation of a key. |
| 241 | */ |
| 242 | struct key *key_get_instantiation_authkey(key_serial_t target_id) |
| 243 | { |
| 244 | char description[16]; |
| 245 | struct keyring_search_context ctx = { |
| 246 | .index_key.type = &key_type_request_key_auth, |
| 247 | .index_key.description = description, |
| 248 | .cred = current_cred(), |
| 249 | .match = user_match, |
| 250 | .match_data = description, |
| 251 | .flags = KEYRING_SEARCH_LOOKUP_DIRECT, |
| 252 | }; |
| 253 | struct key *authkey; |
| 254 | key_ref_t authkey_ref; |
| 255 | |
| 256 | sprintf(description, "%x", target_id); |
| 257 | |
| 258 | authkey_ref = search_process_keyrings(&ctx); |
| 259 | |
| 260 | if (IS_ERR(authkey_ref)) { |
| 261 | authkey = ERR_CAST(authkey_ref); |
| 262 | if (authkey == ERR_PTR(-EAGAIN)) |
| 263 | authkey = ERR_PTR(-ENOKEY); |
| 264 | goto error; |
| 265 | } |
| 266 | |
| 267 | authkey = key_ref_to_ptr(authkey_ref); |
| 268 | if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { |
| 269 | key_put(authkey); |
| 270 | authkey = ERR_PTR(-EKEYREVOKED); |
| 271 | } |
| 272 | |
| 273 | error: |
| 274 | return authkey; |
| 275 | } |