On Tue, Sep 21, 2010 at 1:40 PM, Jeff Layton <jlayton@xxxxxxxxx> wrote: > On Tue, 21 Sep 2010 13:26:08 -0500 > Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote: > >> On Tue, Sep 21, 2010 at 12:52 PM, Jeff Layton <jlayton@xxxxxxxxx> wrote: >> > On Sat, 18 Sep 2010 22:02:35 -0500 >> > shirishpargaonkar@xxxxxxxxx wrote: >> > >> >> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> >> >> >> >> >> >> Mark dependency on crypto modules in Kconfig. >> >> >> >> Defining per structures sdesc and cifs_secmech which are used to store >> >> crypto hash functions and contexts. They are stored per smb connection >> >> and used for all auth mechs to genereate hash values and signatures. >> >> >> >> Allocate crypto hashing functions, security descriptiors, and respective >> >> contexts when a smb/tcp connection is established. >> >> Release them when a tcp/smb connection is taken down. >> >> >> >> md5 and hmac-md5 are two crypto hashing functions that are used >> >> throught the life of an smb/tcp connection by various functions that >> >> calcualte signagure and ntlmv2 hash, HMAC etc. >> >> >> >> structure ntlmssp_auth and filed cphready is defined as per smb connection. >> >> >> >> ntlmssp_auth holds secondary key which is a nonce that gets used as a key >> >> to generate signatures, ciphertext is genereated by rc4/arc4 encryption of >> >> secondary key using ntlmv2 session key and sent in the session key field of >> >> the type 3 message sent by the client during ntlmssp negotiation/exchange >> >> These are per session structures and secondary key and cipher text >> >> get calculated only once per smb connection, during first smb session setup >> >> for that smb connection. >> >> >> >> Field cphready is used to mark such that once secondary keys and ciphertext >> >> are calculated during very first smb session setup for a smb connection >> >> and ciphertext is sent to the server, the same does not happen during >> >> subsequent smb session setups/establishments. >> >> >> >> A key is exchanged with the server if client indicates so in flags in >> >> type 1 messsage and server agrees in flag in type 2 message of ntlmssp >> >> negotiation. If both client and agree, a key sent by client in >> >> type 3 message of ntlmssp negotiation in the session key field. >> >> The key is a ciphertext generated off of secondary key, a nonce, using >> >> ntlmv2 hash via rc4/arc4. >> >> >> >> If authentication is successful, the secondary key is the that client >> >> uses to calculate cifs/smb signature in the messages that client sends >> >> and to verify the messages sent by server. >> >> This key stays with the smb connection for its life and is the key used >> >> to generate (and verify) signatures for all the subsequent smb sessions >> >> for this smb connection. >> >> >> >> So only for the first smb session on any smb connection, type 1 message >> >> of ntlmssp negotiation selects the flag NTLMSSP_NEGOTIATE_KEY_XCH. >> >> It is not used for subsequent smb sessions on this smb connection i.e. >> >> no need to generate secondary key, create ciphertext and send it etc. >> >> >> >> After the very first successful smb session, sequence number gets set >> >> to 0 and variable cphready is used to mark that the key calculations >> >> are done. cphready is reset when a reconnect of the smb connection >> >> happens as sessions get set up again. >> >> >> >> Calculation of ciphertext and setting cphready, is done within >> >> mutex lock to prevent race of smb session setups on a new smb connection. >> >> >> >> >> >> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> >> >> --- >> >> fs/cifs/Kconfig | 3 + >> >> fs/cifs/cifsencrypt.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++ >> >> fs/cifs/cifsglob.h | 28 +++++++++++ >> >> fs/cifs/cifspdu.h | 7 +++ >> >> fs/cifs/cifsproto.h | 3 + >> >> fs/cifs/connect.c | 18 ++++++- >> >> fs/cifs/sess.c | 26 +++++++--- >> >> 7 files changed, 200 insertions(+), 10 deletions(-) >> >> >> >> diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig >> >> index 917b7d4..0ed2139 100644 >> >> --- a/fs/cifs/Kconfig >> >> +++ b/fs/cifs/Kconfig >> >> @@ -2,6 +2,9 @@ config CIFS >> >> tristate "CIFS support (advanced network filesystem, SMBFS successor)" >> >> depends on INET >> >> select NLS >> >> + select CRYPTO >> >> + select CRYPTO_MD5 >> >> + select CRYPTO_ARC4 >> >> help >> >> This is the client VFS module for the Common Internet File System >> >> (CIFS) protocol which is the successor to the Server Message Block >> >> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c >> >> index 730038a..48026c6 100644 >> >> --- a/fs/cifs/cifsencrypt.c >> >> +++ b/fs/cifs/cifsencrypt.c >> >> @@ -477,3 +477,128 @@ void CalcNTLMv2_response(const struct cifsSesInfo *ses, >> >> hmac_md5_final(v2_session_response, &context); >> >> /* cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */ >> >> } >> >> + >> >> +int >> >> +calc_seckey(struct TCP_Server_Info *server) >> >> +{ >> >> + int rc; >> >> + struct crypto_blkcipher *tfm_arc4; >> >> + struct scatterlist sgin, sgout; >> >> + struct blkcipher_desc desc; >> >> + >> >> + if (!server) { >> >> + cERROR(1, "%s: Can't determine ciphertext key\n", __func__); >> >> + return 1; >> >> + } >> >> + >> >> + mutex_lock(&server->srv_mutex); >> >> + if (server->cphready) { >> >> + mutex_unlock(&server->srv_mutex); >> >> + return 0; >> >> + } >> >> + >> >> + get_random_bytes(server->ntlmssp.sec_key, CIFS_NTLMV2_SESSKEY_SIZE); >> >> + >> >> + tfm_arc4 = crypto_alloc_blkcipher("ecb(arc4)", >> >> + 0, CRYPTO_ALG_ASYNC); >> >> + if (!tfm_arc4 || IS_ERR(tfm_arc4)) { >> >> + cERROR(1, "could not allocate crypto API arc4\n"); >> >> + mutex_unlock(&server->srv_mutex); >> >> + return PTR_ERR(tfm_arc4); >> >> + } >> >> + >> >> + desc.tfm = tfm_arc4; >> >> + >> >> + crypto_blkcipher_setkey(tfm_arc4, server->session_key.data.ntlmv2.key, >> >> + CIFS_CPHTXT_SIZE); >> >> + >> >> + sg_init_one(&sgin, server->ntlmssp.sec_key, CIFS_CPHTXT_SIZE); >> >> + sg_init_one(&sgout, server->ntlmssp.ciphertext, CIFS_CPHTXT_SIZE); >> >> + >> >> + rc = crypto_blkcipher_encrypt(&desc, &sgout, &sgin, CIFS_CPHTXT_SIZE); >> >> + if (rc) { >> >> + cERROR(1, "could not encrypt session key rc: %d\n", rc); >> >> + crypto_free_blkcipher(tfm_arc4); >> >> + mutex_unlock(&server->srv_mutex); >> >> + return rc; >> >> + } >> >> + >> >> + crypto_free_blkcipher(tfm_arc4); >> >> + >> >> + server->sequence_number = 0; >> >> + server->cphready = true; >> >> + mutex_unlock(&server->srv_mutex); >> >> + >> >> + return 0; >> >> +} >> >> + >> >> +void >> >> +cifs_crypto_shash_release(struct TCP_Server_Info *server) >> >> +{ >> >> + if (server->secmech.md5) >> >> + crypto_free_shash(server->secmech.md5); >> >> + >> >> + if (server->secmech.hmacmd5) >> >> + crypto_free_shash(server->secmech.hmacmd5); >> >> + >> >> + kfree(server->secmech.sdeschmacmd5); >> >> + >> >> + kfree(server->secmech.sdescmd5); >> >> +} >> >> + >> >> +int >> >> +cifs_crypto_shash_allocate(struct TCP_Server_Info *server) >> >> +{ >> >> + int rc; >> >> + unsigned int size; >> >> + >> >> + server->secmech.hmacmd5 = crypto_alloc_shash("hmac(md5)", 0, 0); >> >> + if (!server->secmech.hmacmd5 || >> >> + IS_ERR(server->secmech.hmacmd5)) { >> >> + cERROR(1, "could not allocate crypto hmacmd5\n"); >> >> + return PTR_ERR(server->secmech.hmacmd5); >> >> + } >> >> + >> >> + server->secmech.md5 = crypto_alloc_shash("md5", 0, 0); >> >> + if (!server->secmech.md5 || IS_ERR(server->secmech.md5)) { >> >> + cERROR(1, "could not allocate crypto md5\n"); >> >> + rc = PTR_ERR(server->secmech.md5); >> >> + goto crypto_allocate_md5_fail; >> >> + } >> >> + >> >> + size = sizeof(struct shash_desc) + >> >> + crypto_shash_descsize(server->secmech.hmacmd5); >> >> + server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL); >> >> + if (!server->secmech.sdeschmacmd5) { >> >> + cERROR(1, "cifs_crypto_shash_allocate: can't alloc hmacmd5\n"); >> >> + rc = -ENOMEM; >> >> + goto crypto_allocate_hmacmd5_sdesc_fail; >> >> + } >> >> + server->secmech.sdeschmacmd5->shash.tfm = server->secmech.hmacmd5; >> >> + server->secmech.sdeschmacmd5->shash.flags = 0x0; >> >> + >> >> + >> >> + size = sizeof(struct shash_desc) + >> >> + crypto_shash_descsize(server->secmech.md5); >> >> + server->secmech.sdescmd5 = kmalloc(size, GFP_KERNEL); >> >> + if (!server->secmech.sdescmd5) { >> >> + cERROR(1, "cifs_crypto_shash_allocate: can't alloc md5\n"); >> >> + rc = -ENOMEM; >> >> + goto crypto_allocate_md5_sdesc_fail; >> >> + } >> >> + server->secmech.sdescmd5->shash.tfm = server->secmech.md5; >> >> + server->secmech.sdescmd5->shash.flags = 0x0; >> >> + >> >> + return 0; >> >> + >> >> +crypto_allocate_md5_sdesc_fail: >> >> + kfree(server->secmech.sdeschmacmd5); >> >> + >> >> +crypto_allocate_hmacmd5_sdesc_fail: >> >> + crypto_free_shash(server->secmech.md5); >> >> + >> >> +crypto_allocate_md5_fail: >> >> + crypto_free_shash(server->secmech.hmacmd5); >> >> + >> >> + return rc; >> >> +} >> >> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h >> >> index c68f31c..c7da866 100644 >> >> --- a/fs/cifs/cifsglob.h >> >> +++ b/fs/cifs/cifsglob.h >> >> @@ -25,6 +25,9 @@ >> >> #include <linux/workqueue.h> >> >> #include "cifs_fs_sb.h" >> >> #include "cifsacl.h" >> >> +#include <crypto/internal/hash.h> >> >> +#include <linux/scatterlist.h> >> >> + >> >> /* >> >> * The sizes of various internal tables and strings >> >> */ >> >> @@ -109,6 +112,28 @@ struct session_key { >> >> } data; >> >> }; >> >> >> >> +/* crypto security descriptor definition */ >> >> +struct sdesc { >> >> + struct shash_desc shash; >> >> + char ctx[]; >> >> +}; >> >> + >> >> +/* crypto hashing related structure/fields, not speicific to a sec mech */ >> >> +struct cifs_secmech { >> >> + struct crypto_shash *hmacmd5; /* hmac-md5 hash function */ >> >> + struct crypto_shash *md5; /* md5 hash function */ >> >> + struct sdesc *sdeschmacmd5; /* ctxt to generate ntlmv2 hash, CR1 */ >> >> + struct sdesc *sdescmd5; /* ctxt to generate cifs/smb signature */ >> >> +}; >> >> + >> >> +/* per smb connection structure/fields */ >> >> +struct ntlmssp_auth { >> >> + __u32 client_flags; /* sent by client in type 1 ntlmsssp exchange */ >> >> + __u32 server_flags; /* sent by server in type 2 ntlmssp exchange */ >> >> + unsigned char sec_key[CIFS_CPHTXT_SIZE]; /* a nonce client generates */ >> >> + unsigned char ciphertext[CIFS_CPHTXT_SIZE]; /* sent to server */ >> >> +}; >> >> + >> >> struct cifs_cred { >> >> int uid; >> >> int gid; >> >> @@ -187,6 +212,9 @@ struct TCP_Server_Info { >> >> unsigned long lstrp; /* when we got last response from this server */ >> >> u16 dialect; /* dialect index that server chose */ >> >> /* extended security flavors that server supports */ >> >> + struct cifs_secmech secmech; /* crypto sec mech functs, descriptors */ >> >> + struct ntlmssp_auth ntlmssp; /* sec key, ciphertext, flags */ >> >> + bool cphready; /* ciphertext is calculated */ >> >> bool sec_kerberos; /* supports plain Kerberos */ >> >> bool sec_mskerberos; /* supports legacy MS Kerberos */ >> >> bool sec_kerberosu2u; /* supports U2U Kerberos */ >> >> diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h >> >> index b0f4b56..dc90a36 100644 >> >> --- a/fs/cifs/cifspdu.h >> >> +++ b/fs/cifs/cifspdu.h >> >> @@ -134,6 +134,13 @@ >> >> * Size of the session key (crypto key encrypted with the password >> >> */ >> >> #define CIFS_SESS_KEY_SIZE (24) >> >> +#define CIFS_CLIENT_CHALLENGE_SIZE (8) >> >> +#define CIFS_SERVER_CHALLENGE_SIZE (8) >> >> +#define CIFS_HMAC_MD5_HASH_SIZE (16) >> >> +#define CIFS_CPHTXT_SIZE (16) >> >> +#define CIFS_NTLMV2_SESSKEY_SIZE (16) >> >> +#define CIFS_NTHASH_SIZE (16) >> >> + >> >> >> >> /* >> >> * Maximum user name length >> >> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h >> >> index c155479..d89a87a 100644 >> >> --- a/fs/cifs/cifsproto.h >> >> +++ b/fs/cifs/cifsproto.h >> >> @@ -369,6 +369,9 @@ extern int cifs_calculate_session_key(struct session_key *key, const char *rn, >> >> extern void CalcNTLMv2_response(const struct cifsSesInfo *, char *); >> >> extern int setup_ntlmv2_rsp(struct cifsSesInfo *, char *, >> >> const struct nls_table *); >> >> +extern int cifs_crypto_shash_allocate(struct TCP_Server_Info *); >> >> +extern void cifs_crypto_shash_release(struct TCP_Server_Info *); >> >> +extern int calc_seckey(struct TCP_Server_Info *); >> >> #ifdef CONFIG_CIFS_WEAK_PW_HASH >> >> extern void calc_lanman_hash(const char *password, const char *cryptkey, >> >> bool encrypt, char *lnm_session_key); >> >> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c >> >> index c99760a..4818089 100644 >> >> --- a/fs/cifs/connect.c >> >> +++ b/fs/cifs/connect.c >> >> @@ -199,6 +199,7 @@ cifs_reconnect(struct TCP_Server_Info *server) >> >> if (server->tcpStatus != CifsExiting) >> >> server->tcpStatus = CifsGood; >> >> server->sequence_number = 0; >> >> + server->cphready = false; >> >> spin_unlock(&GlobalMid_Lock); >> >> /* atomic_set(&server->inFlight,0);*/ >> >> wake_up(&server->response_q); >> >> @@ -1502,6 +1503,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server) >> >> server->tcpStatus = CifsExiting; >> >> spin_unlock(&GlobalMid_Lock); >> >> >> >> + cifs_crypto_shash_release(server); >> >> cifs_fscache_release_client_cookie(server); >> >> >> >> task = xchg(&server->tsk, NULL); >> >> @@ -1556,12 +1558,19 @@ cifs_get_tcp_session(struct smb_vol *volume_info) >> >> goto out_err; >> >> } >> >> >> >> + rc = cifs_crypto_shash_allocate(tcp_ses); >> >> + if (rc) { >> >> + cERROR(1, "could not setup hash structures rc %d", rc); >> >> + goto out_err; >> >> + } >> >> + >> >> tcp_ses->hostname = extract_hostname(volume_info->UNC); >> >> if (IS_ERR(tcp_ses->hostname)) { >> >> rc = PTR_ERR(tcp_ses->hostname); >> >> - goto out_err; >> >> + goto out_err2; >> >> } >> >> >> >> + tcp_ses->cphready = false; >> >> tcp_ses->noblocksnd = volume_info->noblocksnd; >> >> tcp_ses->noautotune = volume_info->noautotune; >> >> tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay; >> >> @@ -1600,7 +1609,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info) >> >> } >> >> if (rc < 0) { >> >> cERROR(1, "Error connecting to socket. Aborting operation"); >> >> - goto out_err; >> >> + goto out_err2; >> >> } >> >> >> >> /* >> >> @@ -1614,7 +1623,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info) >> >> rc = PTR_ERR(tcp_ses->tsk); >> >> cERROR(1, "error %d create cifsd thread", rc); >> >> module_put(THIS_MODULE); >> >> - goto out_err; >> >> + goto out_err2; >> >> } >> >> >> >> /* thread spawned, put it on the list */ >> >> @@ -1626,6 +1635,9 @@ cifs_get_tcp_session(struct smb_vol *volume_info) >> >> >> >> return tcp_ses; >> >> >> >> +out_err2: >> >> + cifs_crypto_shash_release(tcp_ses); >> >> + >> >> out_err: >> >> if (tcp_ses) { >> >> if (!IS_ERR(tcp_ses->hostname)) >> >> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c >> >> index af18a50..45555de 100644 >> >> --- a/fs/cifs/sess.c >> >> +++ b/fs/cifs/sess.c >> >> @@ -407,7 +407,7 @@ static int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len, >> >> /* In particular we can examine sign flags */ >> >> /* BB spec says that if AvId field of MsvAvTimestamp is populated then >> >> we must set the MIC field of the AUTHENTICATE_MESSAGE */ >> >> - >> >> + ses->server->ntlmssp.server_flags = le32_to_cpu(pblob->NegotiateFlags); >> >> tioffset = cpu_to_le16(pblob->TargetInfoArray.BufferOffset); >> >> tilen = cpu_to_le16(pblob->TargetInfoArray.Length); >> >> ses->tilen = tilen; >> >> @@ -443,10 +443,12 @@ static void build_ntlmssp_negotiate_blob(unsigned char *pbuffer, >> >> NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE | >> >> NTLMSSP_NEGOTIATE_NTLM; >> >> if (ses->server->secMode & >> >> - (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) >> >> + (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) { >> >> flags |= NTLMSSP_NEGOTIATE_SIGN; >> >> - if (ses->server->secMode & SECMODE_SIGN_REQUIRED) >> >> - flags |= NTLMSSP_NEGOTIATE_ALWAYS_SIGN; >> >> + if (!ses->server->cphready) >> >> + flags |= NTLMSSP_NEGOTIATE_KEY_XCH | >> >> + NTLMSSP_NEGOTIATE_EXTENDED_SEC; >> >> + } >> >> >> >> sec_blob->NegotiateFlags |= cpu_to_le32(flags); >> >> >> >> @@ -553,9 +555,19 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, >> >> sec_blob->WorkstationName.MaximumLength = 0; >> >> tmp += 2; >> >> >> >> - sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer); >> >> - sec_blob->SessionKey.Length = 0; >> >> - sec_blob->SessionKey.MaximumLength = 0; >> >> + if ((ses->server->ntlmssp.server_flags & NTLMSSP_NEGOTIATE_KEY_XCH) && >> >> + !calc_seckey(ses->server)) { >> >> + memcpy(tmp, ses->server->ntlmssp.ciphertext, CIFS_CPHTXT_SIZE); >> >> + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer); >> >> + sec_blob->SessionKey.Length = cpu_to_le16(CIFS_CPHTXT_SIZE); >> >> + sec_blob->SessionKey.MaximumLength = >> >> + cpu_to_le16(CIFS_CPHTXT_SIZE); >> >> + tmp += CIFS_CPHTXT_SIZE; >> >> + } else { >> >> + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer); >> >> + sec_blob->SessionKey.Length = 0; >> >> + sec_blob->SessionKey.MaximumLength = 0; >> >> + } >> >> >> >> setup_ntlmv2_ret: >> >> return tmp - pbuffer; >> > >> > >> > Ok, so this patch adds this cphready flag to the server struct and >> > changes the ntlmssp code to use it. What about the other authtypes? >> > NTLMv1 and Kerberos use a local "first_time" flag in CIFS_SessSetup. >> > >> > Why did you choose to add cphready instead of using that? If there is a >> > good reason for it, the other authtypes should be changed to use >> > cphready for consistency. >> >> The use of cphready which is a per smb connection structure is to make >> sure that we calculate secondary session key and ciphertext only once >> per smb connection, by the first session setup over that connection. >> The secondary key which becomes session key is used to calculate signatures. >> > > Right. I'm just not sure why we need a separate flag attached to the > server struct for this. Why was the "first_time" mechanism not good > enough here? I see no reason why that wouldn't have worked for NTLMSSP > too. Jeff, I will investigate but at the first glance, it looks like first_ses is per smb session and not smb connection, not sure if that would be good enough for ntlmssp. > > Note that I'm not attached to that mechanism, but I think it should be > consistent for all sectypes. It makes no sense to use this cphready > flag for NTLMSSP and then a completely different mechanism for other > sectypes. If you want to add this, you should convert the other > sectypes to use your new mechanism. > >> We do not have NTLMv1 any more and session key is not used to calculate >> signature for kerberos auth type. >> > > Wrong. From the Kerberos section of CIFS_SessSetup: > > if (first_time) { > ses->server->session_key.len = msg->sesskey_len; > memcpy(ses->server->session_key.data.krb5, > msg->data, msg->sesskey_len); > } > > > It's most definitely used for calculating signatures on sockets that > use krb5 auth. > >> > >> > Also, not directly related to your changes, but it looks like the >> > "plain" ntlmv2 code sets the session_key without any regard for whether >> > it's the first session on the socket. I think that also ought to be >> > fixed, probably in a separate patch. >> >> The same reason for "plain" ntlmv2, session key is not used to >> calcuate signatures. >> > > But it is...the session_key struct holds the pointer to the data that's > used precisely for this. > >> SMB connection/setup combo using NTLMSSP security mechanism is stricter >> about authentication response and signature compared to "plain" ntlmv2 or ntlmv1 >> or ntlm I think. >> > -- > Jeff Layton <jlayton@xxxxxxxxx> > -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html