FreeBSD/Linux Kernel Cross Reference
sys/netsmb/smb_crypt.c

     /*-
      * SPDX-License-Identifier: BSD-4-Clause
      *
      * Copyright (c) 2000-2001, Boris Popov
      * All rights reserved.
      *
      * Copyright (c) 2003, 2004 Tim J. Robbins.
      * All rights reserved.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *    This product includes software developed by Boris Popov.
     * 4. Neither the name of the author nor the names of any co-contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/12.0/sys/netsmb/smb_crypt.c 328238 2018-01-22 02:08:10Z pfg $");
    
    #include <sys/param.h>
    #include <sys/malloc.h>
    #include <sys/kernel.h>
    #include <sys/systm.h>
    #include <sys/conf.h>
    #include <sys/proc.h>
    #include <sys/fcntl.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sysctl.h>
    #include <sys/endian.h>
    #include <sys/mbuf.h>
    #include <sys/mchain.h>
    #include <sys/md4.h>
    #include <sys/md5.h>
    #include <sys/iconv.h>
    
    #include <netsmb/smb.h>
    #include <netsmb/smb_conn.h>
    #include <netsmb/smb_subr.h>
    #include <netsmb/smb_rq.h>
    #include <netsmb/smb_dev.h>
    
    #include <crypto/des/des.h>
    
    #include "opt_netsmb.h"
    
    static u_char N8[] = {0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25};
    
    
    static void
    smb_E(const u_char *key, u_char *data, u_char *dest)
    {
            des_key_schedule *ksp;
            u_char kk[8];
    
            kk[0] = key[0] & 0xfe;
            kk[1] = key[0] << 7 | (key[1] >> 1 & 0xfe);
            kk[2] = key[1] << 6 | (key[2] >> 2 & 0xfe);
            kk[3] = key[2] << 5 | (key[3] >> 3 & 0xfe);
            kk[4] = key[3] << 4 | (key[4] >> 4 & 0xfe);
            kk[5] = key[4] << 3 | (key[5] >> 5 & 0xfe);
            kk[6] = key[5] << 2 | (key[6] >> 6 & 0xfe);
            kk[7] = key[6] << 1;
            ksp = malloc(sizeof(des_key_schedule), M_SMBTEMP, M_WAITOK);
            des_set_key((des_cblock *)kk, *ksp);
            des_ecb_encrypt((des_cblock *)data, (des_cblock *)dest, *ksp, 1);
            free(ksp, M_SMBTEMP);
    }
    
    
    int
    smb_encrypt(const u_char *apwd, u_char *C8, u_char *RN)
    {
            u_char *p, *P14, *S21;
    
            p = malloc(14 + 21, M_SMBTEMP, M_WAITOK);
            bzero(p, 14 + 21);
            P14 = p;
           S21 = p + 14;
           bcopy(apwd, P14, min(14, strlen(apwd)));
           /*
            * S21 = concat(Ex(P14, N8), zeros(5));
            */
           smb_E(P14, N8, S21);
           smb_E(P14 + 7, N8, S21 + 8);
   
           smb_E(S21, C8, RN);
           smb_E(S21 + 7, C8, RN + 8);
           smb_E(S21 + 14, C8, RN + 16);
           free(p, M_SMBTEMP);
           return 0;
   }
   
   int
   smb_ntencrypt(const u_char *apwd, u_char *C8, u_char *RN)
   {
           u_char S21[21];
           u_int16_t *unipwd;
           MD4_CTX *ctxp;
           u_int len;
   
           len = strlen(apwd);
           unipwd = malloc((len + 1) * sizeof(u_int16_t), M_SMBTEMP, M_WAITOK);
           /*
            * S21 = concat(MD4(U(apwd)), zeros(5));
            */
           smb_strtouni(unipwd, apwd);
           ctxp = malloc(sizeof(MD4_CTX), M_SMBTEMP, M_WAITOK);
           MD4Init(ctxp);
           MD4Update(ctxp, (u_char*)unipwd, len * sizeof(u_int16_t));
           free(unipwd, M_SMBTEMP);
           bzero(S21, 21);
           MD4Final(S21, ctxp);
           free(ctxp, M_SMBTEMP);
   
           smb_E(S21, C8, RN);
           smb_E(S21 + 7, C8, RN + 8);
           smb_E(S21 + 14, C8, RN + 16);
           return 0;
   }
   
   /*
    * Calculate message authentication code (MAC) key for virtual circuit.
    */
   int
   smb_calcmackey(struct smb_vc *vcp)
   {
           const char *pwd;
           u_int16_t *unipwd;
           u_int len;
           MD4_CTX md4;
           u_char S16[16], S21[21];
   
           KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
               ("signatures not enabled"));
   
           if (vcp->vc_mackey != NULL) {
                   free(vcp->vc_mackey, M_SMBTEMP);
                   vcp->vc_mackey = NULL;
                   vcp->vc_mackeylen = 0;
                   vcp->vc_seqno = 0;
           }
   
           /*
            * The partial MAC key is the concatenation of the 16 byte session
            * key and the 24 byte challenge response.
            */
           vcp->vc_mackeylen = 16 + 24;
           vcp->vc_mackey = malloc(vcp->vc_mackeylen, M_SMBTEMP, M_WAITOK);
   
           /*
            * Calculate session key:
            *      MD4(MD4(U(PN)))
            */
           pwd = smb_vc_getpass(vcp);
           len = strlen(pwd);
           unipwd = malloc((len + 1) * sizeof(u_int16_t), M_SMBTEMP, M_WAITOK);
           smb_strtouni(unipwd, pwd);
           MD4Init(&md4);
           MD4Update(&md4, (u_char *)unipwd, len * sizeof(u_int16_t));
           MD4Final(S16, &md4);
           MD4Init(&md4);
           MD4Update(&md4, S16, 16);
           MD4Final(vcp->vc_mackey, &md4);
           free(unipwd, M_SMBTEMP);
   
           /*
            * Calculate response to challenge:
            *      Ex(concat(MD4(U(pass)), zeros(5)), C8)
            */
           bzero(S21, 21);
           bcopy(S16, S21, 16);
           smb_E(S21, vcp->vc_ch, vcp->vc_mackey + 16);
           smb_E(S21 + 7, vcp->vc_ch, vcp->vc_mackey + 24);
           smb_E(S21 + 14, vcp->vc_ch, vcp->vc_mackey + 32);
   
           return (0);
   }
   
   /*
    * Sign request with MAC.
    */
   int
   smb_rq_sign(struct smb_rq *rqp)
   {
           struct smb_vc *vcp = rqp->sr_vc;
           struct mbchain *mbp;
           struct mbuf *mb;
           MD5_CTX md5;
           u_char digest[16];
   
           KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
               ("signatures not enabled"));
   
           if (vcp->vc_mackey == NULL)
                   /* XXX Should assert that cmd == SMB_COM_NEGOTIATE. */
                   return (0);
   
           /*
            * This is a bit of a kludge. If the request is non-TRANSACTION,
            * or it is the first request of a transaction, give it the next
            * sequence number, and expect the reply to have the sequence number
            * following that one. Otherwise, it is a secondary request in
            * a transaction, and it gets the same sequence numbers as the
            * primary request.
            */
           if (rqp->sr_t2 == NULL ||
               (rqp->sr_t2->t2_flags & SMBT2_SECONDARY) == 0) {
                   rqp->sr_seqno = vcp->vc_seqno++;
                   rqp->sr_rseqno = vcp->vc_seqno++;
           } else {
                   /*
                    * Sequence numbers are already in the struct because
                    * smb_t2_request_int() uses the same one for all the
                    * requests in the transaction.
                    * (At least we hope so.)
                    */
                   KASSERT(rqp->sr_t2 == NULL ||
                       (rqp->sr_t2->t2_flags & SMBT2_SECONDARY) == 0 ||
                       rqp->sr_t2->t2_rq == rqp,
                       ("sec t2 rq not using same smb_rq"));
           }
   
           /* Initialize sec. signature field to sequence number + zeros. */
           le32enc(rqp->sr_rqsig, rqp->sr_seqno);
           le32enc(rqp->sr_rqsig + 4, 0);
   
           /*
            * Compute HMAC-MD5 of packet data, keyed by MAC key.
            * Store the first 8 bytes in the sec. signature field.
            */
           smb_rq_getrequest(rqp, &mbp);
           MD5Init(&md5);
           MD5Update(&md5, vcp->vc_mackey, vcp->vc_mackeylen);
           for (mb = mbp->mb_top; mb != NULL; mb = mb->m_next)
                   MD5Update(&md5, mtod(mb, void *), mb->m_len);
           MD5Final(digest, &md5);
           bcopy(digest, rqp->sr_rqsig, 8);
   
           return (0);
   }
   
   /*
    * Verify reply signature.
    */
   int
   smb_rq_verify(struct smb_rq *rqp)
   {
           struct smb_vc *vcp = rqp->sr_vc;
           struct mdchain *mdp;
           u_char sigbuf[8];
           MD5_CTX md5;
           u_char digest[16];
           struct mbuf *mb;
   
           KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
               ("signatures not enabled"));
   
           if (vcp->vc_mackey == NULL)
                   /* XXX Should check that this is a SMB_COM_NEGOTIATE reply. */
                   return (0);
   
           /*
            * Compute HMAC-MD5 of packet data, keyed by MAC key.
            * We play games to pretend the security signature field
            * contains their sequence number, to avoid modifying
            * the packet itself.
            */
           smb_rq_getreply(rqp, &mdp);
           mb = mdp->md_top;
           KASSERT(mb->m_len >= SMB_HDRLEN, ("forgot to m_pullup"));
           MD5Init(&md5);
           MD5Update(&md5, vcp->vc_mackey, vcp->vc_mackeylen);
           MD5Update(&md5, mtod(mb, void *), 14);
           *(u_int32_t *)sigbuf = htole32(rqp->sr_rseqno);
           *(u_int32_t *)(sigbuf + 4) = 0;
           MD5Update(&md5, sigbuf, 8);
           MD5Update(&md5, mtod(mb, u_char *) + 22, mb->m_len - 22);
           for (mb = mb->m_next; mb != NULL; mb = mb->m_next)
                   MD5Update(&md5, mtod(mb, void *), mb->m_len);
           MD5Final(digest, &md5);
   
           /*
            * Now verify the signature.
            */
           if (bcmp(mtod(mdp->md_top, u_char *) + 14, digest, 8) != 0)
                   return (EAUTH);
   
           return (0);
   }

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