ba03864872
The DFS referral parsing code does a memchr() call to find the '\\'
delimiter that separates the hostname in the referral UNC from the
sharename. It then uses that value to set the length of the hostname via
pointer subtraction. Instead of subtracting the start of the hostname
however, it subtracts the start of the UNC, which causes the code to
pass in a hostname length that is 2 bytes too long.
Regression introduced in commit 1a4240f4.
Reported-and-Tested-by: Robbert Kouprie <robbert@exx.nl>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Wang Lei <wang840925@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Steve French <sfrench@us.ibm.com>
98 lines
2.8 KiB
C
98 lines
2.8 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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* Wang Lei (wang840925@gmail.com)
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* David Howells (dhowells@redhat.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 <linux/slab.h>
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#include <linux/dns_resolver.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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/**
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* dns_resolve_server_name_to_ip - Resolve UNC server name to ip address.
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* @unc: UNC path specifying the server
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* @ip_addr: Where to return the IP address.
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*
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* The IP address will be returned in string form, and the caller is
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* responsible for freeing it.
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*
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* Returns length of result on success, -ve on error.
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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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struct sockaddr_storage ss;
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const char *hostname, *sep;
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char *name;
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int len, rc;
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if (!ip_addr || !unc)
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return -EINVAL;
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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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/* Discount leading slashes for cifs */
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len -= 2;
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hostname = unc + 2;
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/* Search for server name delimiter */
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sep = memchr(hostname, '\\', len);
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if (sep)
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len = sep - hostname;
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else
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cFYI(1, "%s: probably server name is whole unc: %s",
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__func__, unc);
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/* Try to interpret hostname as an IPv4 or IPv6 address */
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rc = cifs_convert_address((struct sockaddr *)&ss, hostname, len);
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if (rc > 0)
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goto name_is_IP_address;
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/* Perform the upcall */
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rc = dns_query(NULL, hostname, len, NULL, ip_addr, NULL);
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if (rc < 0)
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cERROR(1, "%s: unable to resolve: %*.*s",
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__func__, len, len, hostname);
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else
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cFYI(1, "%s: resolved: %*.*s to %s",
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__func__, len, len, hostname, *ip_addr);
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return rc;
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name_is_IP_address:
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name = kmalloc(len + 1, GFP_KERNEL);
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if (!name)
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return -ENOMEM;
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memcpy(name, hostname, len);
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name[len] = 0;
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cFYI(1, "%s: unc is IP, skipping dns upcall: %s", __func__, name);
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*ip_addr = name;
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return 0;
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}
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