fs/cifs/cifs_spnego.c

   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/string.h>
  24 #include <keys/user-type.h>
  25 #include <linux/key-type.h>
  26 #include "cifsglob.h"
  27 #include "cifs_spnego.h"
  28 #include "cifs_debug.h"
  29
  30 /* create a new cifs key */
  31 static int
  32 cifs_spnego_key_instantiate(struct key *key, const void *data, size_t datalen)
  33 {
  34         char *payload;
  35         int ret;
  36
  37         ret = -ENOMEM;
  38         payload = kmalloc(datalen, GFP_KERNEL);
  39         if (!payload)
  40                 goto error;
  41
  42         /* attach the data */
  43         memcpy(payload, data, datalen);
  44         rcu_assign_pointer(key->payload.data, payload);
  45         ret = 0;
  46
  47 error:
  48         return ret;
  49 }
  50
  51 static void
  52 cifs_spnego_key_destroy(struct key *key)
  53 {
  54         kfree(key->payload.data);
  55 }
  56
  57
  58 /*
  59  * keytype for CIFS spnego keys
  60  */
  61 struct key_type cifs_spnego_key_type = {
  62         .name           = "cifs.spnego",
  63         .instantiate    = cifs_spnego_key_instantiate,
  64         .match          = user_match,
  65         .destroy        = cifs_spnego_key_destroy,
  66         .describe       = user_describe,
  67 };
  68
  69 /* length of longest version string e.g.  strlen("ver=0xFF") */
  70 #define MAX_VER_STR_LEN         8
  71
  72 /* length of longest security mechanism name, eg in future could have
  73  * strlen(";sec=ntlmsspi") */
  74 #define MAX_MECH_STR_LEN        13
  75
  76 /* max possible addr len eg FEDC:BA98:7654:3210:FEDC:BA98:7654:3210/60 */
  77 #define MAX_IPV6_ADDR_LEN       42
  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 ";user=" */
  89 #define USER_KEY_LEN            6
  90
  91 /* get a key struct with a SPNEGO security blob, suitable for session setup */
  92 struct key *
  93 cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
  94 {
  95         struct TCP_Server_Info *server = sesInfo->server;
  96         char *description, *dp;
  97         size_t desc_len;
  98         struct key *spnego_key;
  99         const char *hostname = server->hostname;
 100
 101         /* length of fields (with semicolons): ver=0xyz ip4=ipaddress
 102            host=hostname sec=mechanism uid=0xFF user=username */
 103         desc_len = MAX_VER_STR_LEN +
 104                    HOST_KEY_LEN + strlen(hostname) +
 105                    IP_KEY_LEN + MAX_IPV6_ADDR_LEN +
 106                    MAX_MECH_STR_LEN +
 107                    UID_KEY_LEN + (sizeof(uid_t) * 2) +
 108                    USER_KEY_LEN + strlen(sesInfo->userName) + 1;
 109
 110         spnego_key = ERR_PTR(-ENOMEM);
 111         description = kzalloc(desc_len, GFP_KERNEL);
 112         if (description == NULL)
 113                 goto out;
 114
 115         dp = description;
 116         /* start with version and hostname portion of UNC string */
 117         spnego_key = ERR_PTR(-EINVAL);
 118         sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
 119                 hostname);
 120         dp = description + strlen(description);
 121
 122         /* add the server address */
 123         if (server->addr.sockAddr.sin_family == AF_INET)
 124                 sprintf(dp, "ip4=" NIPQUAD_FMT,
 125                         NIPQUAD(server->addr.sockAddr.sin_addr));
 126         else if (server->addr.sockAddr.sin_family == AF_INET6)
 127                 sprintf(dp, "ip6=" NIP6_SEQFMT,
 128                         NIP6(server->addr.sockAddr6.sin6_addr));
 129         else
 130                 goto out;
 131
 132         dp = description + strlen(description);
 133
 134         /* for now, only sec=krb5 and sec=mskrb5 are valid */
 135         if (server->secType == Kerberos)
 136                 sprintf(dp, ";sec=krb5");
 137         else if (server->secType == MSKerberos)
 138                 sprintf(dp, ";sec=mskrb5");
 139         else
 140                 goto out;
 141
 142         dp = description + strlen(description);
 143         sprintf(dp, ";uid=0x%x", sesInfo->linux_uid);
 144
 145         dp = description + strlen(description);
 146         sprintf(dp, ";user=%s", sesInfo->userName);
 147
 148         cFYI(1, ("key description = %s", description));
 149         spnego_key = request_key(&cifs_spnego_key_type, description, "");
 150
 151 #ifdef CONFIG_CIFS_DEBUG2
 152         if (cifsFYI && !IS_ERR(spnego_key)) {
 153                 struct cifs_spnego_msg *msg = spnego_key->payload.data;
 154                 cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U,
 155                                 msg->secblob_len + msg->sesskey_len));
 156         }
 157 #endif /* CONFIG_CIFS_DEBUG2 */
 158
 159 out:
 160         kfree(description);
 161         return spnego_key;
 162 }