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[CIFS] SMB3 Signing enablement

SMB3 uses a much faster method of signing (which is also better in other ways),
AES-CMAC.  With the kernel now supporting AES-CMAC since last release, we
are overdue to allow SMB3 signing (today only CIFS and SMB2 and SMB2.1,
but not SMB3 and SMB3.1 can sign) - and we need this also for checking
secure negotation and also per-share encryption (two other new SMB3 features
which we need to implement).

This patch needs some work in a few areas - for example we need to
move signing for SMB2/SMB3 from per-socket to per-user (we may be able to
use the "nosharesock" mount option in the interim for the multiuser case),
and Shirish found a bug in the earlier authentication overhaul
(setting signing flags properly) - but those can be done in followon
patches.

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>
master
Steve French 8 years ago
parent
commit
429b46f4fd
  1. 1
      fs/cifs/Kconfig
  2. 29
      fs/cifs/cifsencrypt.c
  3. 3
      fs/cifs/cifsglob.h
  4. 5
      fs/cifs/cifspdu.h
  5. 1
      fs/cifs/cifsproto.h
  6. 1
      fs/cifs/connect.c
  7. 2
      fs/cifs/smb2glob.h
  8. 148
      fs/cifs/smb2transport.c

1
fs/cifs/Kconfig

@ -10,6 +10,7 @@ config CIFS
select CRYPTO_ECB
select CRYPTO_DES
select CRYPTO_SHA256
select CRYPTO_CMAC
help
This is the client VFS module for the Common Internet File System
(CIFS) protocol which is the successor to the Server Message Block

29
fs/cifs/cifsencrypt.c

@ -705,6 +705,9 @@ calc_seckey(struct cifs_ses *ses)
void
cifs_crypto_shash_release(struct TCP_Server_Info *server)
{
if (server->secmech.cmacaes)
crypto_free_shash(server->secmech.cmacaes);
if (server->secmech.hmacsha256)
crypto_free_shash(server->secmech.hmacsha256);
@ -714,6 +717,8 @@ cifs_crypto_shash_release(struct TCP_Server_Info *server)
if (server->secmech.hmacmd5)
crypto_free_shash(server->secmech.hmacmd5);
kfree(server->secmech.sdesccmacaes);
kfree(server->secmech.sdeschmacsha256);
kfree(server->secmech.sdeschmacmd5);
@ -747,6 +752,13 @@ cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
goto crypto_allocate_hmacsha256_fail;
}
server->secmech.cmacaes = crypto_alloc_shash("cmac(aes)", 0, 0);
if (IS_ERR(server->secmech.cmacaes)) {
cifs_dbg(VFS, "could not allocate crypto cmac-aes");
rc = PTR_ERR(server->secmech.cmacaes);
goto crypto_allocate_cmacaes_fail;
}
size = sizeof(struct shash_desc) +
crypto_shash_descsize(server->secmech.hmacmd5);
server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
@ -777,8 +789,22 @@ cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
server->secmech.sdeschmacsha256->shash.tfm = server->secmech.hmacsha256;
server->secmech.sdeschmacsha256->shash.flags = 0x0;
size = sizeof(struct shash_desc) +
crypto_shash_descsize(server->secmech.cmacaes);
server->secmech.sdesccmacaes = kmalloc(size, GFP_KERNEL);
if (!server->secmech.sdesccmacaes) {
cifs_dbg(VFS, "%s: Can't alloc cmacaes\n", __func__);
rc = -ENOMEM;
goto crypto_allocate_cmacaes_sdesc_fail;
}
server->secmech.sdesccmacaes->shash.tfm = server->secmech.cmacaes;
server->secmech.sdesccmacaes->shash.flags = 0x0;
return 0;
crypto_allocate_cmacaes_sdesc_fail:
kfree(server->secmech.sdeschmacsha256);
crypto_allocate_hmacsha256_sdesc_fail:
kfree(server->secmech.sdescmd5);
@ -786,6 +812,9 @@ crypto_allocate_md5_sdesc_fail:
kfree(server->secmech.sdeschmacmd5);
crypto_allocate_hmacmd5_sdesc_fail:
crypto_free_shash(server->secmech.cmacaes);
crypto_allocate_cmacaes_fail:
crypto_free_shash(server->secmech.hmacsha256);
crypto_allocate_hmacsha256_fail:

3
fs/cifs/cifsglob.h

@ -125,9 +125,11 @@ struct cifs_secmech {
struct crypto_shash *hmacmd5; /* hmac-md5 hash function */
struct crypto_shash *md5; /* md5 hash function */
struct crypto_shash *hmacsha256; /* hmac-sha256 hash function */
struct crypto_shash *cmacaes; /* block-cipher based MAC function */
struct sdesc *sdeschmacmd5; /* ctxt to generate ntlmv2 hash, CR1 */
struct sdesc *sdescmd5; /* ctxt to generate cifs/smb signature */
struct sdesc *sdeschmacsha256; /* ctxt to generate smb2 signature */
struct sdesc *sdesccmacaes; /* ctxt to generate smb3 signature */
};
/* per smb session structure/fields */
@ -538,6 +540,7 @@ struct TCP_Server_Info {
int timeAdj; /* Adjust for difference in server time zone in sec */
__u64 CurrentMid; /* multiplex id - rotating counter */
char cryptkey[CIFS_CRYPTO_KEY_SIZE]; /* used by ntlm, ntlmv2 etc */
char smb3signingkey[SMB3_SIGN_KEY_SIZE]; /* for signing smb3 packets */
/* 16th byte of RFC1001 workstation name is always null */
char workstation_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
__u32 sequence_number; /* for signing, protected by srv_mutex */

5
fs/cifs/cifspdu.h

@ -142,6 +142,11 @@
*/
#define CIFS_SESS_KEY_SIZE (16)
/*
* Size of the smb3 signing key
*/
#define SMB3_SIGN_KEY_SIZE (16)
#define CIFS_CLIENT_CHALLENGE_SIZE (8)
#define CIFS_SERVER_CHALLENGE_SIZE (8)
#define CIFS_HMAC_MD5_HASH_SIZE (16)

1
fs/cifs/cifsproto.h

@ -436,6 +436,7 @@ extern int setup_ntlmv2_rsp(struct cifs_ses *, 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 cifs_ses *);
extern int generate_smb3signingkey(struct TCP_Server_Info *);
#ifdef CONFIG_CIFS_WEAK_PW_HASH
extern int calc_lanman_hash(const char *password, const char *cryptkey,

1
fs/cifs/connect.c

@ -3841,6 +3841,7 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
server->sequence_number = 0x2;
server->session_estab = true;
ses->auth_key.response = NULL;
generate_smb3signingkey(server);
}
mutex_unlock(&server->srv_mutex);

2
fs/cifs/smb2glob.h

@ -54,5 +54,7 @@
#define SMB2_SIGNATURE_SIZE (16)
#define SMB2_NTLMV2_SESSKEY_SIZE (16)
#define SMB2_HMACSHA256_SIZE (32)
#define SMB2_CMACAES_SIZE (16)
#define SMB3_SIGNKEY_SIZE (16)
#endif /* _SMB2_GLOB_H */

148
fs/cifs/smb2transport.c

@ -116,11 +116,155 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
return rc;
}
int
generate_smb3signingkey(struct TCP_Server_Info *server)
{
unsigned char zero = 0x0;
__u8 i[4] = {0, 0, 0, 1};
__u8 L[4] = {0, 0, 0, 128};
int rc = 0;
unsigned char prfhash[SMB2_HMACSHA256_SIZE];
unsigned char *hashptr = prfhash;
memset(prfhash, 0x0, SMB2_HMACSHA256_SIZE);
memset(server->smb3signingkey, 0x0, SMB3_SIGNKEY_SIZE);
rc = crypto_shash_setkey(server->secmech.hmacsha256,
server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not set with session key\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init sign hmac\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
i, 4);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with n\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
"SMB2AESCMAC", 12);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
&zero, 1);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with zero\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
"SmbSign", 8);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
L, 4);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with L\n", __func__);
goto smb3signkey_ret;
}
rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
hashptr);
if (rc) {
cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
goto smb3signkey_ret;
}
memcpy(server->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
smb3signkey_ret:
return rc;
}
int
smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
cifs_dbg(FYI, "smb3 signatures not supported yet\n");
return -EOPNOTSUPP;
int i, rc;
unsigned char smb3_signature[SMB2_CMACAES_SIZE];
unsigned char *sigptr = smb3_signature;
struct kvec *iov = rqst->rq_iov;
int n_vec = rqst->rq_nvec;
struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
rc = crypto_shash_setkey(server->secmech.cmacaes,
server->smb3signingkey, SMB2_CMACAES_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
return rc;
}
rc = crypto_shash_init(&server->secmech.sdesccmacaes->shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
return rc;
}
for (i = 0; i < n_vec; i++) {
if (iov[i].iov_len == 0)
continue;
if (iov[i].iov_base == NULL) {
cifs_dbg(VFS, "null iovec entry");
return -EIO;
}
/*
* 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 */
rc =
crypto_shash_update(
&server->secmech.sdesccmacaes->shash,
iov[i].iov_base + 4, iov[i].iov_len - 4);
} else {
rc =
crypto_shash_update(
&server->secmech.sdesccmacaes->shash,
iov[i].iov_base, iov[i].iov_len);
}
if (rc) {
cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
__func__);
return rc;
}
}
/* now hash over the rq_pages array */
for (i = 0; i < rqst->rq_npages; i++) {
struct kvec p_iov;
cifs_rqst_page_to_kvec(rqst, i, &p_iov);
crypto_shash_update(&server->secmech.sdesccmacaes->shash,
p_iov.iov_base, p_iov.iov_len);
kunmap(rqst->rq_pages[i]);
}
rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
sigptr);
if (rc)
cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
return rc;
}
/* must be called with server->srv_mutex held */

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