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 #define MAX_VER_STR_LEN   9 /* length of longest version string e.g.
  70                                 strlen(";ver=0xFF") */
  71 #define MAX_MECH_STR_LEN 13 /* length of longest security mechanism name, eg
  72                                in future could have strlen(";sec=ntlmsspi") */
  73 #define MAX_IPV6_ADDR_LEN 42 /* eg FEDC:BA98:7654:3210:FEDC:BA98:7654:3210/60 */
  74 /* get a key struct with a SPNEGO security blob, suitable for session setup */
  75 struct key *
  76 cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
  77 {
  78         struct TCP_Server_Info *server = sesInfo->server;
  79         char *description, *dp;
  80         size_t desc_len;
  81         struct key *spnego_key;
  82         const char *hostname = server->hostname;
  83
  84         /* BB: come up with better scheme for determining length */
  85         /* length of fields (with semicolons): ver=0xyz ipv4= ipaddress host=
  86            hostname sec=mechanism uid=0x uid */
  87         desc_len = MAX_VER_STR_LEN + 5 + MAX_IPV6_ADDR_LEN + 1 + 6 +
  88                   strlen(hostname) + MAX_MECH_STR_LEN + 8 + (sizeof(uid_t) * 2);
  89         spnego_key = ERR_PTR(-ENOMEM);
  90         description = kzalloc(desc_len, GFP_KERNEL);
  91         if (description == NULL)
  92                 goto out;
  93
  94         dp = description;
  95         /* start with version and hostname portion of UNC string */
  96         spnego_key = ERR_PTR(-EINVAL);
  97         sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
  98                 hostname);
  99         dp = description + strlen(description);
 100
 101         /* add the server address */
 102         if (server->addr.sockAddr.sin_family == AF_INET)
 103                 sprintf(dp, "ip4=" NIPQUAD_FMT,
 104                         NIPQUAD(server->addr.sockAddr.sin_addr));
 105         else if (server->addr.sockAddr.sin_family == AF_INET6)
 106                 sprintf(dp, "ip6=" NIP6_SEQFMT,
 107                         NIP6(server->addr.sockAddr6.sin6_addr));
 108         else
 109                 goto out;
 110
 111         dp = description + strlen(description);
 112
 113         /* for now, only sec=krb5 is valid */
 114         if (server->secType == Kerberos)
 115                 sprintf(dp, ";sec=krb5");
 116         else
 117                 goto out;
 118
 119         dp = description + strlen(description);
 120         sprintf(dp, ";uid=0x%x", sesInfo->linux_uid);
 121
 122         cFYI(1, ("key description = %s", description));
 123         spnego_key = request_key(&cifs_spnego_key_type, description, "");
 124
 125         if (cifsFYI && !IS_ERR(spnego_key)) {
 126                 struct cifs_spnego_msg *msg = spnego_key->payload.data;
 127                 cifs_dump_mem("SPNEGO reply blob:", msg->data,
 128                                 msg->secblob_len + msg->sesskey_len);
 129         }
 130
 131 out:
 132         kfree(description);
 133         return spnego_key;
 134 }