kernel-ark/fs/cifs/cifsencrypt.c
Steve French e9917a000f [CIFS] Incorrect signature sent on SMB Read
Fixes Samba bug 3621 and kernel.org bug 6147

For servers which require SMB/CIFS packet signing, we were sending the
wrong signature (all zeros) on SMB Read request.  The new cifs routine
to do signatures across an iovec was not complete - and SMB Read, unlike
the new SMBWrite2, did not fall back to the older routine (ie use
SendReceive vs. the more efficient SendReceive2 ie used the older
cifs_sign_smb vs. the disabled  cifs_sign_smb2) for calculating signatures.

This finishes up cifs_sign_smb2/cifs_calc_signature2 so that the callers
of SendReceive2 can get SMB/CIFS packet signatures.

Now that cifs_sign_smb2 is supported, we could start using it in
the write path but this smaller fix does not include the change
to use SMBWrite2 when signatures are required (which when enabled
will make more Writes more efficient and alloc less memory).
Currently Write2 is only used when signatures are not
required at the moment but after more testing we will enable
that as well).

Thanks to James Slepicka and Sam Flory for initial investigation.

Signed-off-by: Steve French <sfrench@us.ibm.com>
2006-03-31 21:22:00 +00:00

275 lines
8.3 KiB
C

/*
* fs/cifs/cifsencrypt.c
*
* Copyright (C) International Business Machines Corp., 2005,2006
* Author(s): Steve French (sfrench@us.ibm.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/fs.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifs_debug.h"
#include "md5.h"
#include "cifs_unicode.h"
#include "cifsproto.h"
/* Calculate and return the CIFS signature based on the mac key and the smb pdu */
/* the 16 byte signature must be allocated by the caller */
/* Note we only use the 1st eight bytes */
/* Note that the smb header signature field on input contains the
sequence number before this function is called */
extern void mdfour(unsigned char *out, unsigned char *in, int n);
extern void E_md4hash(const unsigned char *passwd, unsigned char *p16);
static int cifs_calculate_signature(const struct smb_hdr * cifs_pdu,
const char * key, char * signature)
{
struct MD5Context context;
if((cifs_pdu == NULL) || (signature == NULL))
return -EINVAL;
MD5Init(&context);
MD5Update(&context,key,CIFS_SESSION_KEY_SIZE+16);
MD5Update(&context,cifs_pdu->Protocol,cifs_pdu->smb_buf_length);
MD5Final(signature,&context);
return 0;
}
int cifs_sign_smb(struct smb_hdr * cifs_pdu, struct TCP_Server_Info * server,
__u32 * pexpected_response_sequence_number)
{
int rc = 0;
char smb_signature[20];
if((cifs_pdu == NULL) || (server == NULL))
return -EINVAL;
if((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
return rc;
spin_lock(&GlobalMid_Lock);
cifs_pdu->Signature.Sequence.SequenceNumber = cpu_to_le32(server->sequence_number);
cifs_pdu->Signature.Sequence.Reserved = 0;
*pexpected_response_sequence_number = server->sequence_number++;
server->sequence_number++;
spin_unlock(&GlobalMid_Lock);
rc = cifs_calculate_signature(cifs_pdu, server->mac_signing_key,smb_signature);
if(rc)
memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
else
memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
return rc;
}
static int cifs_calc_signature2(const struct kvec * iov, int n_vec,
const char * key, char * signature)
{
struct MD5Context context;
int i;
if((iov == NULL) || (signature == NULL))
return -EINVAL;
MD5Init(&context);
MD5Update(&context,key,CIFS_SESSION_KEY_SIZE+16);
for(i=0;i<n_vec;i++) {
if(iov[i].iov_base == NULL) {
cERROR(1,("null iovec entry"));
return -EIO;
} else if(iov[i].iov_len == 0)
break; /* bail out if we are sent nothing to sign */
/* The first entry includes a length field (which does not get
signed that occupies the first 4 bytes before the header */
if(i==0) {
if (iov[0].iov_len <= 8 ) /* cmd field at offset 9 */
break; /* nothing to sign or corrupt header */
MD5Update(&context,iov[0].iov_base+4, iov[0].iov_len-4);
} else
MD5Update(&context,iov[i].iov_base, iov[i].iov_len);
}
MD5Final(signature,&context);
return 0;
}
int cifs_sign_smb2(struct kvec * iov, int n_vec, struct TCP_Server_Info *server,
__u32 * pexpected_response_sequence_number)
{
int rc = 0;
char smb_signature[20];
struct smb_hdr * cifs_pdu = iov[0].iov_base;
if((cifs_pdu == NULL) || (server == NULL))
return -EINVAL;
if((cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) == 0)
return rc;
spin_lock(&GlobalMid_Lock);
cifs_pdu->Signature.Sequence.SequenceNumber =
cpu_to_le32(server->sequence_number);
cifs_pdu->Signature.Sequence.Reserved = 0;
*pexpected_response_sequence_number = server->sequence_number++;
server->sequence_number++;
spin_unlock(&GlobalMid_Lock);
rc = cifs_calc_signature2(iov, n_vec, server->mac_signing_key,
smb_signature);
if(rc)
memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
else
memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8);
return rc;
}
int cifs_verify_signature(struct smb_hdr * cifs_pdu, const char * mac_key,
__u32 expected_sequence_number)
{
unsigned int rc;
char server_response_sig[8];
char what_we_think_sig_should_be[20];
if((cifs_pdu == NULL) || (mac_key == NULL))
return -EINVAL;
if (cifs_pdu->Command == SMB_COM_NEGOTIATE)
return 0;
if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) {
struct smb_com_lock_req * pSMB = (struct smb_com_lock_req *)cifs_pdu;
if(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE)
return 0;
}
/* BB what if signatures are supposed to be on for session but server does not
send one? BB */
/* Do not need to verify session setups with signature "BSRSPYL " */
if(memcmp(cifs_pdu->Signature.SecuritySignature,"BSRSPYL ",8)==0)
cFYI(1,("dummy signature received for smb command 0x%x",cifs_pdu->Command));
/* save off the origiginal signature so we can modify the smb and check
its signature against what the server sent */
memcpy(server_response_sig,cifs_pdu->Signature.SecuritySignature,8);
cifs_pdu->Signature.Sequence.SequenceNumber = cpu_to_le32(expected_sequence_number);
cifs_pdu->Signature.Sequence.Reserved = 0;
rc = cifs_calculate_signature(cifs_pdu, mac_key,
what_we_think_sig_should_be);
if(rc)
return rc;
/* cifs_dump_mem("what we think it should be: ",what_we_think_sig_should_be,16); */
if(memcmp(server_response_sig, what_we_think_sig_should_be, 8))
return -EACCES;
else
return 0;
}
/* We fill in key by putting in 40 byte array which was allocated by caller */
int cifs_calculate_mac_key(char * key, const char * rn, const char * password)
{
char temp_key[16];
if ((key == NULL) || (rn == NULL))
return -EINVAL;
E_md4hash(password, temp_key);
mdfour(key,temp_key,16);
memcpy(key+16,rn, CIFS_SESSION_KEY_SIZE);
return 0;
}
int CalcNTLMv2_partial_mac_key(struct cifsSesInfo * ses, struct nls_table * nls_info)
{
char temp_hash[16];
struct HMACMD5Context ctx;
char * ucase_buf;
__le16 * unicode_buf;
unsigned int i,user_name_len,dom_name_len;
if(ses == NULL)
return -EINVAL;
E_md4hash(ses->password, temp_hash);
hmac_md5_init_limK_to_64(temp_hash, 16, &ctx);
user_name_len = strlen(ses->userName);
if(user_name_len > MAX_USERNAME_SIZE)
return -EINVAL;
dom_name_len = strlen(ses->domainName);
if(dom_name_len > MAX_USERNAME_SIZE)
return -EINVAL;
ucase_buf = kmalloc((MAX_USERNAME_SIZE+1), GFP_KERNEL);
if(ucase_buf == NULL)
return -ENOMEM;
unicode_buf = kmalloc((MAX_USERNAME_SIZE+1)*4, GFP_KERNEL);
if(unicode_buf == NULL) {
kfree(ucase_buf);
return -ENOMEM;
}
for(i=0;i<user_name_len;i++)
ucase_buf[i] = nls_info->charset2upper[(int)ses->userName[i]];
ucase_buf[i] = 0;
user_name_len = cifs_strtoUCS(unicode_buf, ucase_buf, MAX_USERNAME_SIZE*2, nls_info);
unicode_buf[user_name_len] = 0;
user_name_len++;
for(i=0;i<dom_name_len;i++)
ucase_buf[i] = nls_info->charset2upper[(int)ses->domainName[i]];
ucase_buf[i] = 0;
dom_name_len = cifs_strtoUCS(unicode_buf+user_name_len, ucase_buf, MAX_USERNAME_SIZE*2, nls_info);
unicode_buf[user_name_len + dom_name_len] = 0;
hmac_md5_update((const unsigned char *) unicode_buf,
(user_name_len+dom_name_len)*2,&ctx);
hmac_md5_final(ses->server->mac_signing_key,&ctx);
kfree(ucase_buf);
kfree(unicode_buf);
return 0;
}
void CalcNTLMv2_response(const struct cifsSesInfo * ses,char * v2_session_response)
{
struct HMACMD5Context context;
memcpy(v2_session_response + 8, ses->server->cryptKey,8);
/* gen_blob(v2_session_response + 16); */
hmac_md5_init_limK_to_64(ses->server->mac_signing_key, 16, &context);
hmac_md5_update(ses->server->cryptKey,8,&context);
/* hmac_md5_update(v2_session_response+16)client thing,8,&context); */ /* BB fix */
hmac_md5_final(v2_session_response,&context);
cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); /* BB removeme BB */
}