1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Request key authorisation token key definition. 3 * 4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 * 7 * See Documentation/security/keys/request-key.rst 8 */ 9 10 #include <linux/sched.h> 11 #include <linux/err.h> 12 #include <linux/seq_file.h> 13 #include <linux/slab.h> 14 #include <linux/uaccess.h> 15 #include "internal.h" 16 #include <keys/request_key_auth-type.h> 17 18 static int request_key_auth_preparse(struct key_preparsed_payload *); 19 static void request_key_auth_free_preparse(struct key_preparsed_payload *); 20 static int request_key_auth_instantiate(struct key *, 21 struct key_preparsed_payload *); 22 static void request_key_auth_describe(const struct key *, struct seq_file *); 23 static void request_key_auth_revoke(struct key *); 24 static void request_key_auth_destroy(struct key *); 25 static long request_key_auth_read(const struct key *, char __user *, size_t); 26 27 /* 28 * The request-key authorisation key type definition. 29 */ 30 struct key_type key_type_request_key_auth = { 31 .name = ".request_key_auth", 32 .def_datalen = sizeof(struct request_key_auth), 33 .preparse = request_key_auth_preparse, 34 .free_preparse = request_key_auth_free_preparse, 35 .instantiate = request_key_auth_instantiate, 36 .describe = request_key_auth_describe, 37 .revoke = request_key_auth_revoke, 38 .destroy = request_key_auth_destroy, 39 .read = request_key_auth_read, 40 }; 41 42 static int request_key_auth_preparse(struct key_preparsed_payload *prep) 43 { 44 return 0; 45 } 46 47 static void request_key_auth_free_preparse(struct key_preparsed_payload *prep) 48 { 49 } 50 51 /* 52 * Instantiate a request-key authorisation key. 53 */ 54 static int request_key_auth_instantiate(struct key *key, 55 struct key_preparsed_payload *prep) 56 { 57 key->payload.data[0] = (struct request_key_auth *)prep->data; 58 return 0; 59 } 60 61 /* 62 * Describe an authorisation token. 63 */ 64 static void request_key_auth_describe(const struct key *key, 65 struct seq_file *m) 66 { 67 struct request_key_auth *rka = get_request_key_auth(key); 68 69 seq_puts(m, "key:"); 70 seq_puts(m, key->description); 71 if (key_is_positive(key)) 72 seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); 73 } 74 75 /* 76 * Read the callout_info data (retrieves the callout information). 77 * - the key's semaphore is read-locked 78 */ 79 static long request_key_auth_read(const struct key *key, 80 char __user *buffer, size_t buflen) 81 { 82 struct request_key_auth *rka = get_request_key_auth(key); 83 size_t datalen; 84 long ret; 85 86 datalen = rka->callout_len; 87 ret = datalen; 88 89 /* we can return the data as is */ 90 if (buffer && buflen > 0) { 91 if (buflen > datalen) 92 buflen = datalen; 93 94 if (copy_to_user(buffer, rka->callout_info, buflen) != 0) 95 ret = -EFAULT; 96 } 97 98 return ret; 99 } 100 101 /* 102 * Handle revocation of an authorisation token key. 103 * 104 * Called with the key sem write-locked. 105 */ 106 static void request_key_auth_revoke(struct key *key) 107 { 108 struct request_key_auth *rka = get_request_key_auth(key); 109 110 kenter("{%d}", key->serial); 111 112 if (rka->cred) { 113 put_cred(rka->cred); 114 rka->cred = NULL; 115 } 116 } 117 118 static void free_request_key_auth(struct request_key_auth *rka) 119 { 120 if (!rka) 121 return; 122 key_put(rka->target_key); 123 key_put(rka->dest_keyring); 124 if (rka->cred) 125 put_cred(rka->cred); 126 kfree(rka->callout_info); 127 kfree(rka); 128 } 129 130 /* 131 * Destroy an instantiation authorisation token key. 132 */ 133 static void request_key_auth_destroy(struct key *key) 134 { 135 struct request_key_auth *rka = get_request_key_auth(key); 136 137 kenter("{%d}", key->serial); 138 139 free_request_key_auth(rka); 140 } 141 142 /* 143 * Create an authorisation token for /sbin/request-key or whoever to gain 144 * access to the caller's security data. 145 */ 146 struct key *request_key_auth_new(struct key *target, const char *op, 147 const void *callout_info, size_t callout_len, 148 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 = -ENOMEM; 155 156 kenter("%d,", target->serial); 157 158 /* allocate a auth record */ 159 rka = kzalloc(sizeof(*rka), GFP_KERNEL); 160 if (!rka) 161 goto error; 162 rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL); 163 if (!rka->callout_info) 164 goto error_free_rka; 165 rka->callout_len = callout_len; 166 strlcpy(rka->op, op, sizeof(rka->op)); 167 168 /* see if the calling process is already servicing the key request of 169 * another process */ 170 if (cred->request_key_auth) { 171 /* it is - use that instantiation context here too */ 172 down_read(&cred->request_key_auth->sem); 173 174 /* if the auth key has been revoked, then the key we're 175 * servicing is already instantiated */ 176 if (test_bit(KEY_FLAG_REVOKED, 177 &cred->request_key_auth->flags)) { 178 up_read(&cred->request_key_auth->sem); 179 ret = -EKEYREVOKED; 180 goto error_free_rka; 181 } 182 183 irka = cred->request_key_auth->payload.data[0]; 184 rka->cred = get_cred(irka->cred); 185 rka->pid = irka->pid; 186 187 up_read(&cred->request_key_auth->sem); 188 } 189 else { 190 /* it isn't - use this process as the context */ 191 rka->cred = get_cred(cred); 192 rka->pid = current->pid; 193 } 194 195 rka->target_key = key_get(target); 196 rka->dest_keyring = key_get(dest_keyring); 197 198 /* allocate the auth key */ 199 sprintf(desc, "%x", target->serial); 200 201 authkey = key_alloc(&key_type_request_key_auth, desc, 202 cred->fsuid, cred->fsgid, cred, 203 KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | 204 KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL); 205 if (IS_ERR(authkey)) { 206 ret = PTR_ERR(authkey); 207 goto error_free_rka; 208 } 209 210 /* construct the auth key */ 211 ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); 212 if (ret < 0) 213 goto error_put_authkey; 214 215 kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage)); 216 return authkey; 217 218 error_put_authkey: 219 key_put(authkey); 220 error_free_rka: 221 free_request_key_auth(rka); 222 error: 223 kleave("= %d", ret); 224 return ERR_PTR(ret); 225 } 226 227 /* 228 * Search the current process's keyrings for the authorisation key for 229 * instantiation of a key. 230 */ 231 struct key *key_get_instantiation_authkey(key_serial_t target_id) 232 { 233 char description[16]; 234 struct keyring_search_context ctx = { 235 .index_key.type = &key_type_request_key_auth, 236 .index_key.description = description, 237 .cred = current_cred(), 238 .match_data.cmp = key_default_cmp, 239 .match_data.raw_data = description, 240 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 241 .flags = KEYRING_SEARCH_DO_STATE_CHECK, 242 }; 243 struct key *authkey; 244 key_ref_t authkey_ref; 245 246 ctx.index_key.desc_len = sprintf(description, "%x", target_id); 247 248 authkey_ref = search_process_keyrings(&ctx); 249 250 if (IS_ERR(authkey_ref)) { 251 authkey = ERR_CAST(authkey_ref); 252 if (authkey == ERR_PTR(-EAGAIN)) 253 authkey = ERR_PTR(-ENOKEY); 254 goto error; 255 } 256 257 authkey = key_ref_to_ptr(authkey_ref); 258 if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { 259 key_put(authkey); 260 authkey = ERR_PTR(-EKEYREVOKED); 261 } 262 263 error: 264 return authkey; 265 } 266