Re: [PATCH 3/7 cifs] ntlm authentication and signing - Calculate auth response per smb session

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On Mon, 4 Oct 2010 08:00:57 -0500
Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote:

> On Mon, Oct 4, 2010 at 7:53 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> > On Mon, 4 Oct 2010 07:52:08 -0500
> > Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote:
> >
> >> On Mon, Oct 4, 2010 at 6:02 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> >> > On Wed, 29 Sep 2010 09:39:37 -0500
> >> > shirishpargaonkar@xxxxxxxxx wrote:
> >> >
> >> >> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
> >> >>
> >> >>
> >> >> Start calculation auth response within a session.  Move/Add pertinet
> >> >> data structures like session key, server challenge and ntlmv2_hash in
> >> >> a session structure.  We should do the calculations within a session
> >> >> before copying session key and response over to server data
> >> >> structures because a session setup can fail.
> >> >>
> >> >>
> >> >> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
> >> >> ---
> >> >>  fs/cifs/cifsencrypt.c |   16 ++++++++--------
> >> >>  fs/cifs/cifsglob.h    |    6 ++++--
> >> >>  fs/cifs/cifssmb.c     |    4 ++--
> >> >>  fs/cifs/connect.c     |    7 ++++---
> >> >>  fs/cifs/sess.c        |   17 ++++++++---------
> >> >>  5 files changed, 26 insertions(+), 24 deletions(-)
> >> >>
> >> >> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> >> >> index 7ca9c80..0dda565 100644
> >> >> --- a/fs/cifs/cifsencrypt.c
> >> >> +++ b/fs/cifs/cifsencrypt.c
> >> >> @@ -458,7 +458,7 @@ calc_exit_1:
> >> >>  calc_exit_2:
> >> >>       /* BB FIXME what about bytes 24 through 40 of the signing key?
> >> >>          compare with the NTLM example */
> >> >> -     hmac_md5_final(ses->server->ntlmv2_hash, pctxt);
> >> >> +     hmac_md5_final(ses->ntlmv2_hash, pctxt);
> >> >>
> >> >>       kfree(pctxt);
> >> >>       return rc;
> >> >> @@ -502,14 +502,14 @@ setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
> >> >>       }
> >> >>       CalcNTLMv2_response(ses, resp_buf);
> >> >>
> >> >> -     /* now calculate the MAC key for NTLMv2 */
> >> >> -     hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
> >> >> +     /* now calculate the session key for NTLMv2 */
> >> >> +     hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);
> >> >>       hmac_md5_update(resp_buf, 16, &context);
> >> >> -     hmac_md5_final(ses->server->session_key.data.ntlmv2.key, &context);
> >> >> +     hmac_md5_final(ses->auth_key.data.ntlmv2.key, &context);
> >> >>
> >> >> -     memcpy(&ses->server->session_key.data.ntlmv2.resp, resp_buf,
> >> >> +     memcpy(&ses->auth_key.data.ntlmv2.resp, resp_buf,
> >> >>              sizeof(struct ntlmv2_resp));
> >> >> -     ses->server->session_key.len = 16 + sizeof(struct ntlmv2_resp);
> >> >> +     ses->auth_key.len = 16 + sizeof(struct ntlmv2_resp);
> >> >>
> >> >>       return 0;
> >> >>
> >> >> @@ -526,8 +526,8 @@ void CalcNTLMv2_response(const struct cifsSesInfo *ses,
> >> >>  {
> >> >>       struct HMACMD5Context context;
> >> >>       /* rest of v2 struct already generated */
> >> >> -     memcpy(v2_session_response + 8, ses->server->cryptKey, 8);
> >> >> -     hmac_md5_init_limK_to_64(ses->server->ntlmv2_hash, 16, &context);
> >> >> +     memcpy(v2_session_response + 8, ses->cryptKey, 8);
> >> >> +     hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);
> >> >>
> >> >>       hmac_md5_update(v2_session_response+8,
> >> >>                       sizeof(struct ntlmv2_resp) - 8, &context);
> >> >> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> >> >> index c265ebd..4ae331c 100644
> >> >> --- a/fs/cifs/cifsglob.h
> >> >> +++ b/fs/cifs/cifsglob.h
> >> >> @@ -179,12 +179,10 @@ struct TCP_Server_Info {
> >> >>       int capabilities; /* allow selective disabling of caps by smb sess */
> >> >>       int timeAdj;  /* Adjust for difference in server time zone in sec */
> >> >>       __u16 CurrentMid;         /* multiplex id - rotating counter */
> >> >> -     char cryptKey[CIFS_CRYPTO_KEY_SIZE];
> >> >>       /* 16th byte of RFC1001 workstation name is always null */
> >> >>       char workstation_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
> >> >>       __u32 sequence_number; /* needed for CIFS PDU signature */
> >> >>       struct session_key session_key;
> >> >> -     char ntlmv2_hash[16];
> >> >>       unsigned long lstrp; /* when we got last response from this server */
> >> >>       u16 dialect; /* dialect index that server chose */
> >> >>       /* extended security flavors that server supports */
> >> >> @@ -192,6 +190,7 @@ struct TCP_Server_Info {
> >> >>       bool    sec_mskerberos;         /* supports legacy MS Kerberos */
> >> >>       bool    sec_kerberosu2u;        /* supports U2U Kerberos */
> >> >>       bool    sec_ntlmssp;            /* supports NTLMSSP */
> >> >> +     bool session_estab; /* mark when very first sess is established */
> >> >>  #ifdef CONFIG_CIFS_FSCACHE
> >> >>       struct fscache_cookie   *fscache; /* client index cache cookie */
> >> >>  #endif
> >> >> @@ -223,6 +222,9 @@ struct cifsSesInfo {
> >> >>       char userName[MAX_USERNAME_SIZE + 1];
> >> >>       char *domainName;
> >> >>       char *password;
> >> >> +     char cryptKey[CIFS_CRYPTO_KEY_SIZE];
> >> >> +     struct session_key auth_key;
> >> >> +     char ntlmv2_hash[16];
> >> >>       unsigned int tilen; /* length of the target info blob */
> >> >>       unsigned char *tiblob; /* target info blob in challenge response */
> >> >>       bool need_reconnect:1; /* connection reset, uid now invalid */
> >> >> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> >> >> index 13c854e..0dbc51c 100644
> >> >> --- a/fs/cifs/cifssmb.c
> >> >> +++ b/fs/cifs/cifssmb.c
> >> >> @@ -486,7 +486,7 @@ CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
> >> >>
> >> >>               if (rsp->EncryptionKeyLength ==
> >> >>                               cpu_to_le16(CIFS_CRYPTO_KEY_SIZE)) {
> >> >> -                     memcpy(server->cryptKey, rsp->EncryptionKey,
> >> >> +                     memcpy(ses->cryptKey, rsp->EncryptionKey,
> >> >>                               CIFS_CRYPTO_KEY_SIZE);
> >> >>               } else if (server->secMode & SECMODE_PW_ENCRYPT) {
> >> >>                       rc = -EIO; /* need cryptkey unless plain text */
> >> >> @@ -557,7 +557,7 @@ CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
> >> >>       server->timeAdj = (int)(__s16)le16_to_cpu(pSMBr->ServerTimeZone);
> >> >>       server->timeAdj *= 60;
> >> >>       if (pSMBr->EncryptionKeyLength == CIFS_CRYPTO_KEY_SIZE) {
> >> >> -             memcpy(server->cryptKey, pSMBr->u.EncryptionKey,
> >> >> +             memcpy(ses->cryptKey, pSMBr->u.EncryptionKey,
> >> >>                      CIFS_CRYPTO_KEY_SIZE);
> >> >>       } else if ((pSMBr->hdr.Flags2 & SMBFLG2_EXT_SEC)
> >> >>                       && (pSMBr->EncryptionKeyLength == 0)) {
> >> >> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> >> >> index f6a3091..12a6e20 100644
> >> >> --- a/fs/cifs/connect.c
> >> >> +++ b/fs/cifs/connect.c
> >> >> @@ -200,6 +200,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
> >> >>                       if (server->tcpStatus != CifsExiting)
> >> >>                               server->tcpStatus = CifsGood;
> >> >>                       server->sequence_number = 0;
> >> >> +                     server->session_estab = false;
> >> >>                       spin_unlock(&GlobalMid_Lock);
> >> >>       /*              atomic_set(&server->inFlight,0);*/
> >> >>                       wake_up(&server->response_q);
> >> >> @@ -1616,6 +1617,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
> >> >>               volume_info->source_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
> >> >>       memcpy(tcp_ses->server_RFC1001_name,
> >> >>               volume_info->target_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
> >> >> +     tcp_ses->session_estab = false;
> >> >>       tcp_ses->sequence_number = 0;
> >> >>       INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
> >> >>       INIT_LIST_HEAD(&tcp_ses->smb_ses_list);
> >> >> @@ -2914,14 +2916,13 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses,
> >> >>  #ifdef CONFIG_CIFS_WEAK_PW_HASH
> >> >>               if ((global_secflags & CIFSSEC_MAY_LANMAN) &&
> >> >>                   (ses->server->secType == LANMAN))
> >> >> -                     calc_lanman_hash(tcon->password, ses->server->cryptKey,
> >> >> +                     calc_lanman_hash(tcon->password, ses->cryptKey,
> >> >>                                        ses->server->secMode &
> >> >>                                           SECMODE_PW_ENCRYPT ? true : false,
> >> >>                                        bcc_ptr);
> >> >>               else
> >> >>  #endif /* CIFS_WEAK_PW_HASH */
> >> >> -             SMBNTencrypt(tcon->password, ses->server->cryptKey,
> >> >> -                          bcc_ptr);
> >> >> +             SMBNTencrypt(tcon->password, ses->cryptKey, bcc_ptr);
> >> >>
> >> >>               bcc_ptr += CIFS_SESS_KEY_SIZE;
> >> >>               if (ses->capabilities & CAP_UNICODE) {
> >> >> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
> >> >> index 9148fd8..d632331 100644
> >> >> --- a/fs/cifs/sess.c
> >> >> +++ b/fs/cifs/sess.c
> >> >> @@ -402,7 +402,7 @@ static int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
> >> >>               return -EINVAL;
> >> >>       }
> >> >>
> >> >> -     memcpy(ses->server->cryptKey, pblob->Challenge, CIFS_CRYPTO_KEY_SIZE);
> >> >> +     memcpy(ses->cryptKey, pblob->Challenge, CIFS_CRYPTO_KEY_SIZE);
> >> >>       /* BB we could decode pblob->NegotiateFlags; some may be useful */
> >> >>       /* In particular we can examine sign flags */
> >> >>       /* BB spec says that if AvId field of MsvAvTimestamp is populated then
> >> >> @@ -672,7 +672,7 @@ ssetup_ntlmssp_authenticate:
> >> >>               /* BB calculate hash with password */
> >> >>               /* and copy into bcc */
> >> >>
> >> >> -             calc_lanman_hash(ses->password, ses->server->cryptKey,
> >> >> +             calc_lanman_hash(ses->password, ses->cryptKey,
> >> >>                                ses->server->secMode & SECMODE_PW_ENCRYPT ?
> >> >>                                       true : false, lnm_session_key);
> >> >>
> >> >> @@ -699,12 +699,11 @@ ssetup_ntlmssp_authenticate:
> >> >>                       cpu_to_le16(CIFS_SESS_KEY_SIZE);
> >> >>
> >> >>               /* calculate session key */
> >> >> -             SMBNTencrypt(ses->password, ses->server->cryptKey,
> >> >> -                          ntlm_session_key);
> >> >> +             SMBNTencrypt(ses->password, ses->cryptKey, ntlm_session_key);
> >> >>
> >> >>               if (first_time) /* should this be moved into common code
> >> >> -                               with similar ntlmv2 path? */
> >> >> -                     cifs_calculate_session_key(&ses->server->session_key,
> >> >> +                                with similar ntlmv2 path? */
> >> >> +                     cifs_calculate_session_key(&ses->auth_key,
> >> >>                               ntlm_session_key, ses->password);
> >> >>               /* copy session key */
> >> >>
> >> >> @@ -794,15 +793,15 @@ ssetup_ntlmssp_authenticate:
> >> >>               }
> >> >>               /* bail out if key is too long */
> >> >>               if (msg->sesskey_len >
> >> >> -                 sizeof(ses->server->session_key.data.krb5)) {
> >> >> +                 sizeof(ses->auth_key.data.krb5)) {
> >> >>                       cERROR(1, "Kerberos signing key too long (%u bytes)",
> >> >>                               msg->sesskey_len);
> >> >>                       rc = -EOVERFLOW;
> >> >>                       goto ssetup_exit;
> >> >>               }
> >> >>               if (first_time) {
> >> >> -                     ses->server->session_key.len = msg->sesskey_len;
> >> >> -                     memcpy(ses->server->session_key.data.krb5,
> >> >> +                     ses->auth_key.len = msg->sesskey_len;
> >> >> +                     memcpy(ses->auth_key.data.krb5,
> >> >>                               msg->data, msg->sesskey_len);
> >> >>               }
> >> >>               pSMB->req.hdr.Flags2 |= SMBFLG2_EXT_SEC;
> >> >
> >> > Ok, so basically this moves all of the session key data structures from
> >> > the server to session. Once you calculate the key however and have a
> >> > successful session setup, don't you need to copy that key from the
> >> > session to the server? Where does that happen?
> >> >
> >> > --
> >> > Jeff Layton <jlayton@xxxxxxxxxx>
> >> >
> >>
> >> Jeff, that code is in 5/7 patch.
> >
> > Ok, so to be clear this patchset is "all or nothing"? If you apply just
> > part of them, you'll have a broken tree?
> >
> > --
> > Jeff Layton <jlayton@xxxxxxxxxx>
> >
> 
> Jeff, yes. There are are ifs and buts, but overall answer is, yes,
> "all or nothing"

That makes this far more difficult and time consuming to review than a
series of discrete changes that leave the tree in a non-broken state.
I'll try to get to it when I'm able.

-- 
Jeff Layton <jlayton@xxxxxxxxxx>
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