| 1 | /* |
| 2 | * fs/cifs/cifs_spnego.c -- SPNEGO upcall management for CIFS |
| 3 | * |
| 4 | * Copyright (c) 2007 Red Hat, Inc. |
| 5 | * Author(s): Jeff Layton (jlayton@redhat.com) |
| 6 | * |
| 7 | * This library is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU Lesser General Public License as published |
| 9 | * by the Free Software Foundation; either version 2.1 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * This library is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See |
| 15 | * the GNU Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public License |
| 18 | * along with this library; if not, write to the Free Software |
| 19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 20 | */ |
| 21 | |
| 22 | #include <linux/list.h> |
| 23 | #include <linux/slab.h> |
| 24 | #include <linux/string.h> |
| 25 | #include <keys/user-type.h> |
| 26 | #include <linux/key-type.h> |
| 27 | #include <linux/keyctl.h> |
| 28 | #include <linux/inet.h> |
| 29 | #include "cifsglob.h" |
| 30 | #include "cifs_spnego.h" |
| 31 | #include "cifs_debug.h" |
| 32 | #include "cifsproto.h" |
| 33 | static const struct cred *spnego_cred; |
| 34 | |
| 35 | /* create a new cifs key */ |
| 36 | static int |
| 37 | cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep) |
| 38 | { |
| 39 | char *payload; |
| 40 | int ret; |
| 41 | |
| 42 | ret = -ENOMEM; |
| 43 | payload = kmemdup(prep->data, prep->datalen, GFP_KERNEL); |
| 44 | if (!payload) |
| 45 | goto error; |
| 46 | |
| 47 | /* attach the data */ |
| 48 | key->payload.data[0] = payload; |
| 49 | ret = 0; |
| 50 | |
| 51 | error: |
| 52 | return ret; |
| 53 | } |
| 54 | |
| 55 | static void |
| 56 | cifs_spnego_key_destroy(struct key *key) |
| 57 | { |
| 58 | kfree(key->payload.data[0]); |
| 59 | } |
| 60 | |
| 61 | |
| 62 | /* |
| 63 | * keytype for CIFS spnego keys |
| 64 | */ |
| 65 | struct key_type cifs_spnego_key_type = { |
| 66 | .name = "cifs.spnego", |
| 67 | .instantiate = cifs_spnego_key_instantiate, |
| 68 | .destroy = cifs_spnego_key_destroy, |
| 69 | .describe = user_describe, |
| 70 | }; |
| 71 | |
| 72 | /* length of longest version string e.g. strlen("ver=0xFF") */ |
| 73 | #define MAX_VER_STR_LEN 8 |
| 74 | |
| 75 | /* length of longest security mechanism name, eg in future could have |
| 76 | * strlen(";sec=ntlmsspi") */ |
| 77 | #define MAX_MECH_STR_LEN 13 |
| 78 | |
| 79 | /* strlen of "host=" */ |
| 80 | #define HOST_KEY_LEN 5 |
| 81 | |
| 82 | /* strlen of ";ip4=" or ";ip6=" */ |
| 83 | #define IP_KEY_LEN 5 |
| 84 | |
| 85 | /* strlen of ";uid=0x" */ |
| 86 | #define UID_KEY_LEN 7 |
| 87 | |
| 88 | /* strlen of ";creduid=0x" */ |
| 89 | #define CREDUID_KEY_LEN 11 |
| 90 | |
| 91 | /* strlen of ";user=" */ |
| 92 | #define USER_KEY_LEN 6 |
| 93 | |
| 94 | /* strlen of ";pid=0x" */ |
| 95 | #define PID_KEY_LEN 7 |
| 96 | |
| 97 | /* get a key struct with a SPNEGO security blob, suitable for session setup */ |
| 98 | struct key * |
| 99 | cifs_get_spnego_key(struct cifs_ses *sesInfo) |
| 100 | { |
| 101 | struct TCP_Server_Info *server = sesInfo->server; |
| 102 | struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr; |
| 103 | struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr; |
| 104 | char *description, *dp; |
| 105 | size_t desc_len; |
| 106 | struct key *spnego_key; |
| 107 | const char *hostname = server->hostname; |
| 108 | const struct cred *saved_cred; |
| 109 | |
| 110 | /* length of fields (with semicolons): ver=0xyz ip4=ipaddress |
| 111 | host=hostname sec=mechanism uid=0xFF user=username */ |
| 112 | desc_len = MAX_VER_STR_LEN + |
| 113 | HOST_KEY_LEN + strlen(hostname) + |
| 114 | IP_KEY_LEN + INET6_ADDRSTRLEN + |
| 115 | MAX_MECH_STR_LEN + |
| 116 | UID_KEY_LEN + (sizeof(uid_t) * 2) + |
| 117 | CREDUID_KEY_LEN + (sizeof(uid_t) * 2) + |
| 118 | PID_KEY_LEN + (sizeof(pid_t) * 2) + 1; |
| 119 | |
| 120 | if (sesInfo->user_name) |
| 121 | desc_len += USER_KEY_LEN + strlen(sesInfo->user_name); |
| 122 | |
| 123 | spnego_key = ERR_PTR(-ENOMEM); |
| 124 | description = kzalloc(desc_len, GFP_KERNEL); |
| 125 | if (description == NULL) |
| 126 | goto out; |
| 127 | |
| 128 | dp = description; |
| 129 | /* start with version and hostname portion of UNC string */ |
| 130 | spnego_key = ERR_PTR(-EINVAL); |
| 131 | sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION, |
| 132 | hostname); |
| 133 | dp = description + strlen(description); |
| 134 | |
| 135 | /* add the server address */ |
| 136 | if (server->dstaddr.ss_family == AF_INET) |
| 137 | sprintf(dp, "ip4=%pI4", &sa->sin_addr); |
| 138 | else if (server->dstaddr.ss_family == AF_INET6) |
| 139 | sprintf(dp, "ip6=%pI6", &sa6->sin6_addr); |
| 140 | else |
| 141 | goto out; |
| 142 | |
| 143 | dp = description + strlen(description); |
| 144 | |
| 145 | /* for now, only sec=krb5 and sec=mskrb5 are valid */ |
| 146 | if (server->sec_kerberos) |
| 147 | sprintf(dp, ";sec=krb5"); |
| 148 | else if (server->sec_mskerberos) |
| 149 | sprintf(dp, ";sec=mskrb5"); |
| 150 | else |
| 151 | goto out; |
| 152 | |
| 153 | dp = description + strlen(description); |
| 154 | sprintf(dp, ";uid=0x%x", |
| 155 | from_kuid_munged(&init_user_ns, sesInfo->linux_uid)); |
| 156 | |
| 157 | dp = description + strlen(description); |
| 158 | sprintf(dp, ";creduid=0x%x", |
| 159 | from_kuid_munged(&init_user_ns, sesInfo->cred_uid)); |
| 160 | |
| 161 | if (sesInfo->user_name) { |
| 162 | dp = description + strlen(description); |
| 163 | sprintf(dp, ";user=%s", sesInfo->user_name); |
| 164 | } |
| 165 | |
| 166 | dp = description + strlen(description); |
| 167 | sprintf(dp, ";pid=0x%x", current->pid); |
| 168 | |
| 169 | cifs_dbg(FYI, "key description = %s\n", description); |
| 170 | saved_cred = override_creds(spnego_cred); |
| 171 | spnego_key = request_key(&cifs_spnego_key_type, description, ""); |
| 172 | revert_creds(saved_cred); |
| 173 | |
| 174 | #ifdef CONFIG_CIFS_DEBUG2 |
| 175 | if (cifsFYI && !IS_ERR(spnego_key)) { |
| 176 | struct cifs_spnego_msg *msg = spnego_key->payload.data[0]; |
| 177 | cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U, |
| 178 | msg->secblob_len + msg->sesskey_len)); |
| 179 | } |
| 180 | #endif /* CONFIG_CIFS_DEBUG2 */ |
| 181 | |
| 182 | out: |
| 183 | kfree(description); |
| 184 | return spnego_key; |
| 185 | } |
| 186 | |
| 187 | int |
| 188 | init_cifs_spnego(void) |
| 189 | { |
| 190 | struct cred *cred; |
| 191 | struct key *keyring; |
| 192 | int ret; |
| 193 | |
| 194 | cifs_dbg(FYI, "Registering the %s key type\n", |
| 195 | cifs_spnego_key_type.name); |
| 196 | |
| 197 | /* |
| 198 | * Create an override credential set with special thread keyring for |
| 199 | * spnego upcalls. |
| 200 | */ |
| 201 | |
| 202 | cred = prepare_kernel_cred(NULL); |
| 203 | if (!cred) |
| 204 | return -ENOMEM; |
| 205 | |
| 206 | keyring = keyring_alloc(".cifs_spnego", |
| 207 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, |
| 208 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | |
| 209 | KEY_USR_VIEW | KEY_USR_READ, |
| 210 | KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); |
| 211 | if (IS_ERR(keyring)) { |
| 212 | ret = PTR_ERR(keyring); |
| 213 | goto failed_put_cred; |
| 214 | } |
| 215 | |
| 216 | ret = register_key_type(&cifs_spnego_key_type); |
| 217 | if (ret < 0) |
| 218 | goto failed_put_key; |
| 219 | |
| 220 | /* |
| 221 | * instruct request_key() to use this special keyring as a cache for |
| 222 | * the results it looks up |
| 223 | */ |
| 224 | set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags); |
| 225 | cred->thread_keyring = keyring; |
| 226 | cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; |
| 227 | spnego_cred = cred; |
| 228 | |
| 229 | cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring)); |
| 230 | return 0; |
| 231 | |
| 232 | failed_put_key: |
| 233 | key_put(keyring); |
| 234 | failed_put_cred: |
| 235 | put_cred(cred); |
| 236 | return ret; |
| 237 | } |
| 238 | |
| 239 | void |
| 240 | exit_cifs_spnego(void) |
| 241 | { |
| 242 | key_revoke(spnego_cred->thread_keyring); |
| 243 | unregister_key_type(&cifs_spnego_key_type); |
| 244 | put_cred(spnego_cred); |
| 245 | cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name); |
| 246 | } |