167 lines
3.7 KiB
C
167 lines
3.7 KiB
C
/*
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* fs/cifs/dns_resolve.c
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*
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* Copyright (c) 2007 Igor Mammedov
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* Author(s): Igor Mammedov (niallain@gmail.com)
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* Steve French (sfrench@us.ibm.com)
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*
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* Contains the CIFS DFS upcall routines used for hostname to
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* IP address translation.
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <keys/user-type.h>
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#include "dns_resolve.h"
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifs_debug.h"
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static int dns_resolver_instantiate(struct key *key, const void *data,
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size_t datalen)
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{
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int rc = 0;
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char *ip;
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ip = kmalloc(datalen+1, GFP_KERNEL);
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if (!ip)
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return -ENOMEM;
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memcpy(ip, data, datalen);
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ip[datalen] = '\0';
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rcu_assign_pointer(key->payload.data, ip);
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return rc;
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}
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struct key_type key_type_dns_resolver = {
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.name = "dns_resolver",
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.def_datalen = sizeof(struct in_addr),
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.describe = user_describe,
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.instantiate = dns_resolver_instantiate,
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.match = user_match,
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};
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/* Checks if supplied name is IP address
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* returns:
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* 1 - name is IP
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* 0 - name is not IP
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*/
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static int is_ip(const char *name)
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{
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int rc;
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struct sockaddr_in sin_server;
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struct sockaddr_in6 sin_server6;
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rc = cifs_inet_pton(AF_INET, name,
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&sin_server.sin_addr.s_addr);
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if (rc <= 0) {
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/* not ipv4 address, try ipv6 */
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rc = cifs_inet_pton(AF_INET6, name,
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&sin_server6.sin6_addr.in6_u);
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if (rc > 0)
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return 1;
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} else {
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return 1;
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}
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/* we failed translating address */
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return 0;
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}
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/* Resolves server name to ip address.
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* input:
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* unc - server UNC
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* output:
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* *ip_addr - pointer to server ip, caller responcible for freeing it.
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* return 0 on success
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*/
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int
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dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
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{
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int rc = -EAGAIN;
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struct key *rkey = ERR_PTR(-EAGAIN);
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char *name;
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char *data = NULL;
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int len;
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if (!ip_addr || !unc)
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return -EINVAL;
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/* search for server name delimiter */
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len = strlen(unc);
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if (len < 3) {
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cFYI(1, ("%s: unc is too short: %s", __func__, unc));
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return -EINVAL;
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}
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len -= 2;
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name = memchr(unc+2, '\\', len);
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if (!name) {
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cFYI(1, ("%s: probably server name is whole unc: %s",
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__func__, unc));
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} else {
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len = (name - unc) - 2/* leading // */;
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}
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name = kmalloc(len+1, GFP_KERNEL);
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if (!name) {
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rc = -ENOMEM;
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return rc;
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}
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memcpy(name, unc+2, len);
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name[len] = 0;
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if (is_ip(name)) {
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cFYI(1, ("%s: it is IP, skipping dns upcall: %s",
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__func__, name));
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data = name;
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goto skip_upcall;
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}
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rkey = request_key(&key_type_dns_resolver, name, "");
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if (!IS_ERR(rkey)) {
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data = rkey->payload.data;
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cFYI(1, ("%s: resolved: %s to %s", __func__,
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rkey->description,
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*ip_addr
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));
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} else {
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cERROR(1, ("%s: unable to resolve: %s", __func__, name));
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goto out;
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}
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skip_upcall:
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if (data) {
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len = strlen(data);
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*ip_addr = kmalloc(len+1, GFP_KERNEL);
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if (*ip_addr) {
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memcpy(*ip_addr, data, len);
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(*ip_addr)[len] = '\0';
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rc = 0;
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} else {
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rc = -ENOMEM;
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}
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if (!IS_ERR(rkey))
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key_put(rkey);
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}
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out:
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kfree(name);
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return rc;
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}
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