linux/fs/cifs/cifs_spnego.c
Jeff Layton 3e4b3e1f68 cifs: add separate cred_uid field to sesInfo
Right now, there's no clear separation between the uid that owns the
credentials used to do the mount and the overriding owner of the files
on that mount.

Add a separate cred_uid field that is set to the real uid
of the mount user. Unlike the linux_uid, the uid= option does not
override this parameter. The parm is sent to cifs.upcall, which can then
preferentially use the creduid= parm instead of the uid= parm for
finding credentials.

This is not the only way to solve this. We could try to do all of this
in kernel instead by having a module parameter that affects what gets
passed in the uid= field of the upcall. That said, we have a lot more
flexibility to change things in userspace so I think it probably makes
sense to do it this way.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2010-08-02 12:40:39 +00:00

170 lines
4.5 KiB
C

/*
* fs/cifs/cifs_spnego.c -- SPNEGO upcall management for CIFS
*
* Copyright (c) 2007 Red Hat, Inc.
* Author(s): Jeff Layton (jlayton@redhat.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <keys/user-type.h>
#include <linux/key-type.h>
#include <linux/inet.h>
#include "cifsglob.h"
#include "cifs_spnego.h"
#include "cifs_debug.h"
/* create a new cifs key */
static int
cifs_spnego_key_instantiate(struct key *key, const void *data, size_t datalen)
{
char *payload;
int ret;
ret = -ENOMEM;
payload = kmalloc(datalen, GFP_KERNEL);
if (!payload)
goto error;
/* attach the data */
memcpy(payload, data, datalen);
key->payload.data = payload;
ret = 0;
error:
return ret;
}
static void
cifs_spnego_key_destroy(struct key *key)
{
kfree(key->payload.data);
}
/*
* keytype for CIFS spnego keys
*/
struct key_type cifs_spnego_key_type = {
.name = "cifs.spnego",
.instantiate = cifs_spnego_key_instantiate,
.match = user_match,
.destroy = cifs_spnego_key_destroy,
.describe = user_describe,
};
/* length of longest version string e.g. strlen("ver=0xFF") */
#define MAX_VER_STR_LEN 8
/* length of longest security mechanism name, eg in future could have
* strlen(";sec=ntlmsspi") */
#define MAX_MECH_STR_LEN 13
/* strlen of "host=" */
#define HOST_KEY_LEN 5
/* strlen of ";ip4=" or ";ip6=" */
#define IP_KEY_LEN 5
/* strlen of ";uid=0x" */
#define UID_KEY_LEN 7
/* strlen of ";user=" */
#define USER_KEY_LEN 6
/* strlen of ";pid=0x" */
#define PID_KEY_LEN 7
/* get a key struct with a SPNEGO security blob, suitable for session setup */
struct key *
cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
{
struct TCP_Server_Info *server = sesInfo->server;
char *description, *dp;
size_t desc_len;
struct key *spnego_key;
const char *hostname = server->hostname;
/* length of fields (with semicolons): ver=0xyz ip4=ipaddress
host=hostname sec=mechanism uid=0xFF user=username */
desc_len = MAX_VER_STR_LEN +
HOST_KEY_LEN + strlen(hostname) +
IP_KEY_LEN + INET6_ADDRSTRLEN +
MAX_MECH_STR_LEN +
UID_KEY_LEN + (sizeof(uid_t) * 2) +
USER_KEY_LEN + strlen(sesInfo->userName) +
PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;
spnego_key = ERR_PTR(-ENOMEM);
description = kzalloc(desc_len, GFP_KERNEL);
if (description == NULL)
goto out;
dp = description;
/* start with version and hostname portion of UNC string */
spnego_key = ERR_PTR(-EINVAL);
sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
hostname);
dp = description + strlen(description);
/* add the server address */
if (server->addr.sockAddr.sin_family == AF_INET)
sprintf(dp, "ip4=%pI4", &server->addr.sockAddr.sin_addr);
else if (server->addr.sockAddr.sin_family == AF_INET6)
sprintf(dp, "ip6=%pI6", &server->addr.sockAddr6.sin6_addr);
else
goto out;
dp = description + strlen(description);
/* for now, only sec=krb5 and sec=mskrb5 are valid */
if (server->sec_kerberos)
sprintf(dp, ";sec=krb5");
else if (server->sec_mskerberos)
sprintf(dp, ";sec=mskrb5");
else
goto out;
dp = description + strlen(description);
sprintf(dp, ";uid=0x%x", sesInfo->linux_uid);
dp = description + strlen(description);
sprintf(dp, ";creduid=0x%x", sesInfo->cred_uid);
dp = description + strlen(description);
sprintf(dp, ";user=%s", sesInfo->userName);
dp = description + strlen(description);
sprintf(dp, ";pid=0x%x", current->pid);
cFYI(1, "key description = %s", description);
spnego_key = request_key(&cifs_spnego_key_type, description, "");
#ifdef CONFIG_CIFS_DEBUG2
if (cifsFYI && !IS_ERR(spnego_key)) {
struct cifs_spnego_msg *msg = spnego_key->payload.data;
cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U,
msg->secblob_len + msg->sesskey_len));
}
#endif /* CONFIG_CIFS_DEBUG2 */
out:
kfree(description);
return spnego_key;
}