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// SPDX-License-Identifier: LGPL-2.1
/*
* fs/cifs/cifs_spnego.c -- SPNEGO upcall management for CIFS
*
* Copyright (c) 2007 Red Hat, Inc.
* Author(s): Jeff Layton (jlayton@redhat.com)
*
*/
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <keys/user-type.h>
#include <linux/key-type.h>
#include <linux/keyctl.h>
#include <linux/inet.h>
#include "cifsglob.h"
#include "cifs_spnego.h"
#include "cifs_debug.h"
#include "cifsproto.h"
static const struct cred *spnego_cred;
/* create a new cifs key */
static int
cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
{
char *payload;
int ret;
ret = -ENOMEM;
payload = kmemdup(prep->data, prep->datalen, GFP_KERNEL);
if (!payload)
goto error;
/* attach the data */
key->payload.data[0] = payload;
ret = 0;
error:
return ret;
}
static void
cifs_spnego_key_destroy(struct key *key)
{
kfree(key->payload.data[0]);
}
/*
* keytype for CIFS spnego keys
*/
struct key_type cifs_spnego_key_type = {
.name = "cifs.spnego",
.instantiate = cifs_spnego_key_instantiate,
.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 ";creduid=0x" */
#define CREDUID_KEY_LEN 11
/* 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 cifs_ses *sesInfo)
{
struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
char *description, *dp;
size_t desc_len;
struct key *spnego_key;
const char *hostname = server->hostname;
const struct cred *saved_cred;
/* 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) +
CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;
if (sesInfo->user_name)
desc_len += USER_KEY_LEN + strlen(sesInfo->user_name);
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->dstaddr.ss_family == AF_INET)
sprintf(dp, "ip4=%pI4", &sa->sin_addr);
else if (server->dstaddr.ss_family == AF_INET6)
sprintf(dp, "ip6=%pI6", &sa6->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 {
cifs_dbg(VFS, "unknown or missing server auth type, use krb5\n");
sprintf(dp, ";sec=krb5");
}
dp = description + strlen(description);
sprintf(dp, ";uid=0x%x",
from_kuid_munged(&init_user_ns, sesInfo->linux_uid));
dp = description + strlen(description);
sprintf(dp, ";creduid=0x%x",
from_kuid_munged(&init_user_ns, sesInfo->cred_uid));
if (sesInfo->user_name) {
dp = description + strlen(description);
sprintf(dp, ";user=%s", sesInfo->user_name);
}
dp = description + strlen(description);
sprintf(dp, ";pid=0x%x", current->pid);
cifs_dbg(FYI, "key description = %s\n", description);
saved_cred = override_creds(spnego_cred);
spnego_key = request_key(&cifs_spnego_key_type, description, "");
revert_creds(saved_cred);
#ifdef CONFIG_CIFS_DEBUG2
if (cifsFYI && !IS_ERR(spnego_key)) {
struct cifs_spnego_msg *msg = spnego_key->payload.data[0];
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;
}
int
init_cifs_spnego(void)
{
struct cred *cred;
struct key *keyring;
int ret;
cifs_dbg(FYI, "Registering the %s key type\n",
cifs_spnego_key_type.name);
/*
* Create an override credential set with special thread keyring for
* spnego upcalls.
*/
cred = prepare_kernel_cred(NULL);
if (!cred)
return -ENOMEM;
keyring = keyring_alloc(".cifs_spnego",
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
(KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ,
KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto failed_put_cred;
}
ret = register_key_type(&cifs_spnego_key_type);
if (ret < 0)
goto failed_put_key;
/*
* instruct request_key() to use this special keyring as a cache for
* the results it looks up
*/
set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
cred->thread_keyring = keyring;
cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
spnego_cred = cred;
cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring));
return 0;
failed_put_key:
key_put(keyring);
failed_put_cred:
put_cred(cred);
return ret;
}
void
exit_cifs_spnego(void)
{
key_revoke(spnego_cred->thread_keyring);
unregister_key_type(&cifs_spnego_key_type);
put_cred(spnego_cred);
cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name);
}
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