Add support for SMB request signing, which prevents "man in the middle"
attacks and is required to connect to Windows 2003 servers in their default configuration. This adds an extra field to the SMB header containing the truncated 64-bit MD5 digest of a key (a function of the user's password and the server's authentication challenge), an implicit sequence number, and the message data itself. As signing each message imposes a significant performance penalty, we only enable it if the server will not let us connect without it; this should eventually become an option to mount_smbfs.
This commit is contained in:
Tim J. Robbins
parent
ade996adb6
commit
190b2c4f8a
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=124087
@ -405,6 +405,9 @@ smb_vc_create(struct smb_vcspec *vcspec,
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vcp->vc_mode = vcspec->rights & SMBM_MASK;
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vcp->obj.co_flags = vcspec->flags & (SMBV_PRIVATE | SMBV_SINGLESHARE);
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vcp->vc_tdesc = &smb_tran_nbtcp_desc;
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vcp->vc_seqno = 0;
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vcp->vc_mackey = NULL;
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vcp->vc_mackeylen = 0;
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if (uid == SMBM_ANY_OWNER)
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uid = realuid;
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@ -474,6 +477,8 @@ smb_vc_free(struct smb_connobj *cp)
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SMB_STRFREE(vcp->vc_srvname);
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SMB_STRFREE(vcp->vc_pass);
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SMB_STRFREE(vcp->vc_domain);
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if (vcp->vc_mackey)
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free(vcp->vc_mackey, M_SMBTEMP);
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if (vcp->vc_paddr)
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free(vcp->vc_paddr, M_SONAME);
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if (vcp->vc_laddr)
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@ -268,6 +268,9 @@ struct smb_vc {
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int vc_wxmax; /* max writex data size */
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struct smbiod * vc_iod;
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struct smb_slock vc_stlock;
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u_int32_t vc_seqno; /* my next sequence number */
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u_int8_t *vc_mackey; /* MAC key */
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int vc_mackeylen; /* length of MAC key */
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};
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#define vc_maxmux vc_sopt.sv_maxmux
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@ -2,6 +2,9 @@
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* Copyright (c) 2000-2001, Boris Popov
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* All rights reserved.
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*
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* Copyright (c) 2003, 2004 Tim J. Robbins.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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@ -43,13 +46,17 @@ __FBSDID("$FreeBSD$");
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <sys/endian.h>
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#include <sys/mbuf.h>
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#include <sys/mchain.h>
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#include <sys/md4.h>
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#include <sys/md5.h>
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#include <sys/iconv.h>
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#include <netsmb/smb.h>
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#include <netsmb/smb_conn.h>
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#include <netsmb/smb_subr.h>
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#include <netsmb/smb_rq.h>
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#include <netsmb/smb_dev.h>
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#include "opt_netsmb.h"
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@ -146,3 +153,187 @@ smb_ntencrypt(const u_char *apwd, u_char *C8, u_char *RN)
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#endif
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}
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/*
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* Calculate message authentication code (MAC) key for virtual circuit.
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*/
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int
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smb_calcmackey(struct smb_vc *vcp)
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{
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#ifdef NETSMBCRYPTO
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const char *pwd;
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u_int16_t *unipwd;
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int len;
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MD4_CTX md4;
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u_char S16[16], S21[21];
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KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
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("signatures not enabled"));
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if (vcp->vc_mackey != NULL) {
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free(vcp->vc_mackey, M_SMBTEMP);
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vcp->vc_mackey = NULL;
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vcp->vc_mackeylen = 0;
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vcp->vc_seqno = 0;
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}
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/*
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* The partial MAC key is the concatenation of the 16 byte session
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* key and the 24 byte challenge response.
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*/
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vcp->vc_mackeylen = 16 + 24;
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vcp->vc_mackey = malloc(vcp->vc_mackeylen, M_SMBTEMP, M_WAITOK);
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/*
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* Calculate session key:
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* MD4(MD4(U(PN)))
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*/
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pwd = smb_vc_getpass(vcp);
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len = strlen(pwd);
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unipwd = malloc((len + 1) * sizeof(u_int16_t), M_SMBTEMP, M_WAITOK);
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smb_strtouni(unipwd, pwd);
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MD4Init(&md4);
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MD4Update(&md4, (u_char *)unipwd, len * sizeof(u_int16_t));
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MD4Final(S16, &md4);
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MD4Init(&md4);
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MD4Update(&md4, S16, 16);
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MD4Final(vcp->vc_mackey, &md4);
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free(unipwd, M_SMBTEMP);
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/*
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* Calculate response to challenge:
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* Ex(concat(MD4(U(pass)), zeros(5)), C8)
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*/
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bzero(S21, 21);
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bcopy(S16, S21, 16);
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smb_E(S21, vcp->vc_ch, vcp->vc_mackey + 16);
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smb_E(S21 + 7, vcp->vc_ch, vcp->vc_mackey + 24);
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smb_E(S21 + 14, vcp->vc_ch, vcp->vc_mackey + 32);
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return (0);
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#else
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panic("smb_calcmackey: encryption not available");
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return (0);
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#endif /* NETSMBCRYPTO */
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}
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/*
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* Sign request with MAC.
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*/
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int
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smb_rq_sign(struct smb_rq *rqp)
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{
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#ifdef NETSMBCRYPTO
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struct smb_vc *vcp = rqp->sr_vc;
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struct mbchain *mbp;
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struct mbuf *mb;
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MD5_CTX md5;
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u_char digest[16];
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KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
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("signatures not enabled"));
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if (vcp->vc_mackey == NULL)
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/* XXX Should assert that cmd == SMB_COM_NEGOTIATE. */
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return (0);
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/*
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* This is a bit of a kludge. If the request is non-TRANSACTION,
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* or it is the first request of a transaction, give it the next
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* sequence number, and expect the reply to have the sequence number
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* following that one. Otherwise, it is a secondary request in
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* a transaction, and it gets the same sequence numbers as the
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* primary request.
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*/
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if (rqp->sr_t2 == NULL ||
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(rqp->sr_t2->t2_flags & SMBT2_SECONDARY) == 0) {
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rqp->sr_seqno = vcp->vc_seqno++;
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rqp->sr_rseqno = vcp->vc_seqno++;
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} else {
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/*
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* Sequence numbers are already in the struct because
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* smb_t2_request_int() uses the same one for all the
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* requests in the transaction.
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* (At least we hope so.)
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*/
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KASSERT(rqp->sr_t2 == NULL ||
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(rqp->sr_t2->t2_flags & SMBT2_SECONDARY) == 0 ||
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rqp->sr_t2->t2_rq == rqp,
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("sec t2 rq not using same smb_rq"));
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}
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/* Initialize sec. signature field to sequence number + zeros. */
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*(u_int32_t *)rqp->sr_rqsig = htole32(rqp->sr_seqno);
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*(u_int32_t *)(rqp->sr_rqsig + 4) = 0;
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/*
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* Compute HMAC-MD5 of packet data, keyed by MAC key.
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* Store the first 8 bytes in the sec. signature field.
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*/
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smb_rq_getrequest(rqp, &mbp);
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MD5Init(&md5);
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MD5Update(&md5, vcp->vc_mackey, vcp->vc_mackeylen);
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for (mb = mbp->mb_top; mb != NULL; mb = mb->m_next)
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MD5Update(&md5, mtod(mb, void *), mb->m_len);
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MD5Final(digest, &md5);
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bcopy(digest, rqp->sr_rqsig, 8);
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return (0);
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#else
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panic("smb_rq_sign: encryption not available");
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return (0);
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#endif /* NETSMBCRYPTO */
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}
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/*
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* Verify reply signature.
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*/
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int
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smb_rq_verify(struct smb_rq *rqp)
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{
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#ifdef NETSMBCRYPTO
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struct smb_vc *vcp = rqp->sr_vc;
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struct mdchain *mdp;
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u_char sigbuf[8];
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MD5_CTX md5;
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u_char digest[16];
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struct mbuf *mb;
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KASSERT(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE,
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("signatures not enabled"));
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if (vcp->vc_mackey == NULL)
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/* XXX Should check that this is a SMB_COM_NEGOTIATE reply. */
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return (0);
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/*
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* Compute HMAC-MD5 of packet data, keyed by MAC key.
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* We play games to pretend the security signature field
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* contains their sequence number, to avoid modifying
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* the packet itself.
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*/
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smb_rq_getreply(rqp, &mdp);
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mb = mdp->md_top;
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KASSERT(mb->m_len >= SMB_HDRLEN, ("forgot to m_pullup"));
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MD5Init(&md5);
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MD5Update(&md5, vcp->vc_mackey, vcp->vc_mackeylen);
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MD5Update(&md5, mtod(mb, void *), 14);
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*(u_int32_t *)sigbuf = htole32(rqp->sr_rseqno);
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*(u_int32_t *)(sigbuf + 4) = 0;
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MD5Update(&md5, sigbuf, 8);
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MD5Update(&md5, mtod(mb, u_char *) + 22, mb->m_len - 22);
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for (mb = mb->m_next; mb != NULL; mb = mb->m_next)
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MD5Update(&md5, mtod(mb, void *), mb->m_len);
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MD5Final(digest, &md5);
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/*
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* Now verify the signature.
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*/
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if (bcmp(mtod(mdp->md_top, u_char *) + 14, digest, 8) != 0)
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return (EAUTH);
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return (0);
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#else
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panic("smb_rq_verify: encryption not available");
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return (0);
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#endif /* NETSMBCRYPTO */
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}
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@ -247,6 +247,8 @@ smb_iod_sendrq(struct smbiod *iod, struct smb_rq *rqp)
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*rqp->sr_rqtid = htole16(ssp ? ssp->ss_tid : SMB_TID_UNKNOWN);
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*rqp->sr_rquid = htole16(vcp ? vcp->vc_smbuid : 0);
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mb_fixhdr(&rqp->sr_rq);
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if (vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE)
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smb_rq_sign(rqp);
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}
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if (rqp->sr_sendcnt++ > 5) {
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rqp->sr_flags |= SMBR_RESTART;
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@ -114,6 +114,7 @@ smb_rq_new(struct smb_rq *rqp, u_char cmd)
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struct smb_vc *vcp = rqp->sr_vc;
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struct mbchain *mbp = &rqp->sr_rq;
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int error;
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u_int16_t flags2;
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rqp->sr_sendcnt = 0;
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mb_done(mbp);
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@ -125,11 +126,20 @@ smb_rq_new(struct smb_rq *rqp, u_char cmd)
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mb_put_uint8(mbp, cmd);
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mb_put_uint32le(mbp, 0); /* DosError */
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mb_put_uint8(mbp, vcp->vc_hflags);
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flags2 = vcp->vc_hflags2;
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if (cmd == SMB_COM_TRANSACTION || cmd == SMB_COM_TRANSACTION_SECONDARY)
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mb_put_uint16le(mbp, (vcp->vc_hflags2 & ~SMB_FLAGS2_UNICODE));
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else
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mb_put_uint16le(mbp, vcp->vc_hflags2);
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mb_put_mem(mbp, tzero, 12, MB_MSYSTEM);
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flags2 &= ~SMB_FLAGS2_UNICODE;
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if (cmd == SMB_COM_NEGOTIATE)
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flags2 &= ~SMB_FLAGS2_SECURITY_SIGNATURE;
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mb_put_uint16le(mbp, flags2);
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if ((flags2 & SMB_FLAGS2_SECURITY_SIGNATURE) == 0) {
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mb_put_mem(mbp, tzero, 12, MB_MSYSTEM);
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rqp->sr_rqsig = NULL;
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} else {
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mb_put_uint16le(mbp, 0 /*scred->sc_p->p_pid >> 16*/);
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rqp->sr_rqsig = (u_int8_t *)mb_reserve(mbp, 8);
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mb_put_uint16le(mbp, 0);
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}
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rqp->sr_rqtid = (u_int16_t*)mb_reserve(mbp, sizeof(u_int16_t));
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mb_put_uint16le(mbp, 1 /*scred->sc_p->p_pid & 0xffff*/);
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rqp->sr_rquid = (u_int16_t*)mb_reserve(mbp, sizeof(u_int16_t));
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@ -349,6 +359,10 @@ smb_rq_reply(struct smb_rq *rqp)
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error = md_get_uint16le(mdp, &rqp->sr_rpuid);
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error = md_get_uint16le(mdp, &rqp->sr_rpmid);
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if (error == 0 &&
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(rqp->sr_vc->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE))
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error = smb_rq_verify(rqp);
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SMBSDEBUG("M:%04x, P:%04x, U:%04x, T:%04x, E: %d:%d\n",
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rqp->sr_rpmid, rqp->sr_rppid, rqp->sr_rpuid, rqp->sr_rptid,
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rqp->sr_errclass, rqp->sr_serror);
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@ -575,6 +589,7 @@ smb_t2_request_int(struct smb_t2rq *t2p)
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return error;
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rqp->sr_flags |= SMBR_MULTIPACKET;
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t2p->t2_rq = rqp;
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rqp->sr_t2 = t2p;
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mbp = &rqp->sr_rq;
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smb_rq_wstart(rqp);
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mb_put_uint16le(mbp, totpcount);
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@ -649,6 +664,7 @@ smb_t2_request_int(struct smb_t2rq *t2p)
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if (error)
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goto bad;
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while (leftpcount || leftdcount) {
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t2p->t2_flags |= SMBT2_SECONDARY;
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error = smb_rq_new(rqp, t2p->t_name ?
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SMB_COM_TRANSACTION_SECONDARY : SMB_COM_TRANSACTION2_SECONDARY);
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if (error)
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@ -54,6 +54,7 @@
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#define SMBT2_ALLOCED 0x0004
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#define SMBT2_RESTART 0x0008
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#define SMBT2_NORESTART 0x0010
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#define SMBT2_SECONDARY 0x0020 /* secondary request */
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#define SMBRQ_SLOCK(rqp) smb_sl_lock(&(rqp)->sr_slock)
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#define SMBRQ_SUNLOCK(rqp) smb_sl_unlock(&(rqp)->sr_slock)
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@ -75,6 +76,8 @@ struct smb_rq {
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struct smb_vc * sr_vc;
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struct smb_share* sr_share;
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u_short sr_mid;
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u_int32_t sr_seqno;
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u_int32_t sr_rseqno;
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struct mbchain sr_rq;
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u_int8_t sr_rqflags;
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u_int16_t sr_rqflags2;
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@ -91,6 +94,7 @@ struct smb_rq {
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int sr_sendcnt;
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struct timespec sr_timesent;
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int sr_lerror;
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u_int8_t * sr_rqsig;
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u_int16_t * sr_rqtid;
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u_int16_t * sr_rquid;
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u_int8_t sr_errclass;
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@ -103,7 +107,7 @@ struct smb_rq {
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u_int16_t sr_rpuid;
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u_int16_t sr_rpmid;
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struct smb_slock sr_slock; /* short term locks */
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/* struct smb_t2rq*sr_t2;*/
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struct smb_t2rq * sr_t2;
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TAILQ_ENTRY(smb_rq) sr_link;
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};
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@ -55,6 +55,8 @@ __FBSDID("$FreeBSD$");
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#include <netsmb/smb_conn.h>
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#include <netsmb/smb_tran.h>
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#include "opt_netsmb.h"
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struct smb_dialect {
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int d_id;
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const char * d_name;
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@ -80,24 +82,29 @@ smb_vc_maxread(struct smb_vc *vcp)
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/*
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* Specs say up to 64k data bytes, but Windows traffic
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* uses 60k... no doubt for some good reason.
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*
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* Don't exceed the server's buffer size if signatures
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* are enabled otherwise Windows 2003 chokes. Allow space
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* for the SMB header & a little bit extra.
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*/
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if (vcp->vc_sopt.sv_caps & SMB_CAP_LARGE_READX)
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if ((vcp->vc_sopt.sv_caps & SMB_CAP_LARGE_READX) &&
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(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE) == 0)
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return (60*1024);
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else
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return (vcp->vc_sopt.sv_maxtx);
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return (vcp->vc_sopt.sv_maxtx - SMB_HDRLEN - 64);
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}
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static u_int32_t
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smb_vc_maxwrite(struct smb_vc *vcp)
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{
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/*
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* Specs say up to 64k data bytes, but Windows traffic
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* uses 60k... probably for some good reason.
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* See comment above.
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*/
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if (vcp->vc_sopt.sv_caps & SMB_CAP_LARGE_WRITEX)
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if ((vcp->vc_sopt.sv_caps & SMB_CAP_LARGE_WRITEX) &&
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(vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE) == 0)
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return (60*1024);
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else
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return (vcp->vc_sopt.sv_maxtx);
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return (vcp->vc_sopt.sv_maxtx - SMB_HDRLEN - 64);
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}
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static int
|
||||
@ -190,6 +197,10 @@ smb_smb_negotiate(struct smb_vc *vcp, struct smb_cred *scred)
|
||||
vcp->vc_chlen = sblen;
|
||||
vcp->obj.co_flags |= SMBV_ENCRYPT;
|
||||
}
|
||||
#ifdef NETSMBCRYPTO
|
||||
if (sp->sv_sm & SMB_SM_SIGS_REQUIRE)
|
||||
vcp->vc_hflags2 |= SMB_FLAGS2_SECURITY_SIGNATURE;
|
||||
#endif
|
||||
vcp->vc_hflags2 |= SMB_FLAGS2_KNOWS_LONG_NAMES;
|
||||
if (dp->d_id == SMB_DIALECT_NTLM0_12 &&
|
||||
sp->sv_maxtx < 4096 &&
|
||||
@ -385,6 +396,8 @@ smb_smb_ssnsetup(struct smb_vc *vcp, struct smb_cred *scred)
|
||||
smb_rq_bend(rqp);
|
||||
if (ntencpass)
|
||||
free(ntencpass, M_SMBTEMP);
|
||||
if (vcp->vc_hflags2 & SMB_FLAGS2_SECURITY_SIGNATURE)
|
||||
smb_calcmackey(vcp);
|
||||
error = smb_rq_simple(rqp);
|
||||
SMBSDEBUG("%d\n", error);
|
||||
if (error) {
|
||||
|
||||
@ -114,6 +114,7 @@ void smb_strfree(char *s);
|
||||
void smb_memfree(void *s);
|
||||
void *smb_zmalloc(unsigned long size, struct malloc_type *type, int flags);
|
||||
|
||||
int smb_calcmackey(struct smb_vc *vcp);
|
||||
int smb_encrypt(const u_char *apwd, u_char *C8, u_char *RN);
|
||||
int smb_ntencrypt(const u_char *apwd, u_char *C8, u_char *RN);
|
||||
int smb_maperror(int eclass, int eno);
|
||||
@ -123,5 +124,7 @@ int smb_put_dstring(struct mbchain *mbp, struct smb_vc *vcp,
|
||||
const char *src, int caseopt);
|
||||
int smb_put_string(struct smb_rq *rqp, const char *src);
|
||||
int smb_put_asunistring(struct smb_rq *rqp, const char *src);
|
||||
int smb_rq_sign(struct smb_rq *rqp);
|
||||
int smb_rq_verify(struct smb_rq *rqp);
|
||||
|
||||
#endif /* !_NETSMB_SMB_SUBR_H_ */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user