fs/cifs/smb2transport.c - third_party/linux - Git at Google

 /*
  *   fs/cifs/smb2transport.c
  *
  *   Copyright (C) International Business Machines  Corp., 2002, 2011
  *                 Etersoft, 2012
  *   Author(s): Steve French (sfrench@us.ibm.com)
  *              Jeremy Allison (jra@samba.org) 2006
  *              Pavel Shilovsky (pshilovsky@samba.org) 2012
  *
  *   This library is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU Lesser General Public License as published
  *   by the Free Software Foundation; either version 2.1 of the License, or
  *   (at your option) any later version.
  *
  *   This library is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  *   the GNU Lesser General Public License for more details.
  *
  *   You should have received a copy of the GNU Lesser General Public License
  *   along with this library; if not, write to the Free Software
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  */

 #include <linux/fs.h>
 #include <linux/list.h>
 #include <linux/wait.h>
 #include <linux/net.h>
 #include <linux/delay.h>
 #include <linux/uaccess.h>
 #include <asm/processor.h>
 #include <linux/mempool.h>
 #include <linux/highmem.h>
 #include <crypto/aead.h>
 #include "smb2pdu.h"
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "smb2proto.h"
 #include "cifs_debug.h"
 #include "smb2status.h"
 #include "smb2glob.h"

 static int
 smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	return cifs_alloc_hash("hmac(sha256)",
 			       &server->secmech.hmacsha256,
 			       &server->secmech.sdeschmacsha256);
 }

 static int
 smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	struct cifs_secmech *p = &server->secmech;
 	int rc;

 	rc = cifs_alloc_hash("hmac(sha256)",
 			     &p->hmacsha256,
 			     &p->sdeschmacsha256);
 	if (rc)
 		goto err;

 	rc = cifs_alloc_hash("cmac(aes)", &p->cmacaes, &p->sdesccmacaes);
 	if (rc)
 		goto err;

 	return 0;
 err:
 	cifs_free_hash(&p->hmacsha256, &p->sdeschmacsha256);
 	return rc;
 }

 #ifdef CONFIG_CIFS_SMB311
 int
 smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	struct cifs_secmech *p = &server->secmech;
 	int rc = 0;

 	rc = cifs_alloc_hash("hmac(sha256)",
 			     &p->hmacsha256,
 			     &p->sdeschmacsha256);
 	if (rc)
 		return rc;

 	rc = cifs_alloc_hash("cmac(aes)", &p->cmacaes, &p->sdesccmacaes);
 	if (rc)
 		goto err;

 	rc = cifs_alloc_hash("sha512", &p->sha512, &p->sdescsha512);
 	if (rc)
 		goto err;

 	return 0;

 err:
 	cifs_free_hash(&p->cmacaes, &p->sdesccmacaes);
 	cifs_free_hash(&p->hmacsha256, &p->sdeschmacsha256);
 	return rc;
 }
 #endif

 static struct cifs_ses *
 smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id)
 {
 	struct cifs_ses *ses;

 	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 		if (ses->Suid != ses_id)
 			continue;
 		return ses;
 	}

 	return NULL;
 }

 struct cifs_ses *
 smb2_find_smb_ses(struct TCP_Server_Info *server, __u64 ses_id)
 {
 	struct cifs_ses *ses;

 	spin_lock(&cifs_tcp_ses_lock);
 	ses = smb2_find_smb_ses_unlocked(server, ses_id);
 	spin_unlock(&cifs_tcp_ses_lock);

 	return ses;
 }

 static struct cifs_tcon *
 smb2_find_smb_sess_tcon_unlocked(struct cifs_ses *ses, __u32  tid)
 {
 	struct cifs_tcon *tcon;

 	list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 		if (tcon->tid != tid)
 			continue;
 		++tcon->tc_count;
 		return tcon;
 	}

 	return NULL;
 }

 /*
  * Obtain tcon corresponding to the tid in the given
  * cifs_ses
  */

 struct cifs_tcon *
 smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32  tid)
 {
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon;

 	spin_lock(&cifs_tcp_ses_lock);
 	ses = smb2_find_smb_ses_unlocked(server, ses_id);
 	if (!ses) {
 		spin_unlock(&cifs_tcp_ses_lock);
 		return NULL;
 	}
 	tcon = smb2_find_smb_sess_tcon_unlocked(ses, tid);
 	spin_unlock(&cifs_tcp_ses_lock);

 	return tcon;
 }

 int
 smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc;
 	unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
 	unsigned char *sigptr = smb2_signature;
 	struct kvec *iov = rqst->rq_iov;
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[0].iov_base;
 	struct cifs_ses *ses;
 	struct shash_desc *shash = &server->secmech.sdeschmacsha256->shash;
 	struct smb_rqst drqst;

 	ses = smb2_find_smb_ses(server, shdr->SessionId);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}

 	memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
 	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

 	rc = smb2_crypto_shash_allocate(server);
 	if (rc) {
 		cifs_dbg(VFS, "%s: shah256 alloc failed\n", __func__);
 		return rc;
 	}

 	rc = crypto_shash_setkey(server->secmech.hmacsha256,
 				 ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
 		return rc;
 	}

 	rc = crypto_shash_init(shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not init sha256", __func__);
 		return rc;
 	}

 	/*
 	 * For SMB2+, __cifs_calc_signature() expects to sign only the actual
 	 * data, that is, iov[0] should not contain a rfc1002 length.
 	 *
 	 * Sign the rfc1002 length prior to passing the data (iov[1-N]) down to
 	 * __cifs_calc_signature().
 	 */
 	drqst = *rqst;
 	if (drqst.rq_nvec >= 2 && iov[0].iov_len == 4) {
 		rc = crypto_shash_update(shash, iov[0].iov_base,
 					 iov[0].iov_len);
 		if (rc) {
 			cifs_dbg(VFS, "%s: Could not update with payload\n",
 				 __func__);
 			return rc;
 		}
 		drqst.rq_iov++;
 		drqst.rq_nvec--;
 	}

 	rc = __cifs_calc_signature(&drqst, server, sigptr, shash);
 	if (!rc)
 		memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

 	return rc;
 }

 static int generate_key(struct cifs_ses *ses, struct kvec label,
 			struct kvec context, __u8 *key, unsigned int key_size)
 {
 	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(key, 0x0, key_size);

 	rc = smb3_crypto_shash_allocate(ses->server);
 	if (rc) {
 		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
 		goto smb3signkey_ret;
 	}

 	rc = crypto_shash_setkey(ses->server->secmech.hmacsha256,
 		ses->auth_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(&ses->server->secmech.sdeschmacsha256->shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not init sign hmac\n", __func__);
 		goto smb3signkey_ret;
 	}

 	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
 				label.iov_base, label.iov_len);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
 		goto smb3signkey_ret;
 	}

 	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
 				context.iov_base, context.iov_len);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
 		goto smb3signkey_ret;
 	}

 	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
 				hashptr);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
 		goto smb3signkey_ret;
 	}

 	memcpy(key, hashptr, key_size);

 smb3signkey_ret:
 	return rc;
 }

 struct derivation {
 	struct kvec label;
 	struct kvec context;
 };

 struct derivation_triplet {
 	struct derivation signing;
 	struct derivation encryption;
 	struct derivation decryption;
 };

 static int
 generate_smb3signingkey(struct cifs_ses *ses,
 			const struct derivation_triplet *ptriplet)
 {
 	int rc;

 	rc = generate_key(ses, ptriplet->signing.label,
 			  ptriplet->signing.context, ses->smb3signingkey,
 			  SMB3_SIGN_KEY_SIZE);
 	if (rc)
 		return rc;

 	rc = generate_key(ses, ptriplet->encryption.label,
 			  ptriplet->encryption.context, ses->smb3encryptionkey,
 			  SMB3_SIGN_KEY_SIZE);
 	if (rc)
 		return rc;

 	rc = generate_key(ses, ptriplet->decryption.label,
 			  ptriplet->decryption.context,
 			  ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);

 	if (rc)
 		return rc;

 #ifdef CONFIG_CIFS_DEBUG_DUMP_KEYS
 	cifs_dbg(VFS, "%s: dumping generated AES session keys\n", __func__);
 	/*
 	 * The session id is opaque in terms of endianness, so we can't
 	 * print it as a long long. we dump it as we got it on the wire
 	 */
 	cifs_dbg(VFS, "Session Id    %*ph\n", (int)sizeof(ses->Suid),
 			&ses->Suid);
 	cifs_dbg(VFS, "Session Key   %*ph\n",
 		 SMB2_NTLMV2_SESSKEY_SIZE, ses->auth_key.response);
 	cifs_dbg(VFS, "Signing Key   %*ph\n",
 		 SMB3_SIGN_KEY_SIZE, ses->smb3signingkey);
 	cifs_dbg(VFS, "ServerIn Key  %*ph\n",
 		 SMB3_SIGN_KEY_SIZE, ses->smb3encryptionkey);
 	cifs_dbg(VFS, "ServerOut Key %*ph\n",
 		 SMB3_SIGN_KEY_SIZE, ses->smb3decryptionkey);
 #endif
 	return rc;
 }

 int
 generate_smb30signingkey(struct cifs_ses *ses)

 {
 	struct derivation_triplet triplet;
 	struct derivation *d;

 	d = &triplet.signing;
 	d->label.iov_base = "SMB2AESCMAC";
 	d->label.iov_len = 12;
 	d->context.iov_base = "SmbSign";
 	d->context.iov_len = 8;

 	d = &triplet.encryption;
 	d->label.iov_base = "SMB2AESCCM";
 	d->label.iov_len = 11;
 	d->context.iov_base = "ServerIn ";
 	d->context.iov_len = 10;

 	d = &triplet.decryption;
 	d->label.iov_base = "SMB2AESCCM";
 	d->label.iov_len = 11;
 	d->context.iov_base = "ServerOut";
 	d->context.iov_len = 10;

 	return generate_smb3signingkey(ses, &triplet);
 }

 #ifdef CONFIG_CIFS_SMB311
 int
 generate_smb311signingkey(struct cifs_ses *ses)

 {
 	struct derivation_triplet triplet;
 	struct derivation *d;

 	d = &triplet.signing;
 	d->label.iov_base = "SMBSigningKey";
 	d->label.iov_len = 14;
 	d->context.iov_base = ses->preauth_sha_hash;
 	d->context.iov_len = 64;

 	d = &triplet.encryption;
 	d->label.iov_base = "SMBC2SCipherKey";
 	d->label.iov_len = 16;
 	d->context.iov_base = ses->preauth_sha_hash;
 	d->context.iov_len = 64;

 	d = &triplet.decryption;
 	d->label.iov_base = "SMBS2CCipherKey";
 	d->label.iov_len = 16;
 	d->context.iov_base = ses->preauth_sha_hash;
 	d->context.iov_len = 64;

 	return generate_smb3signingkey(ses, &triplet);
 }
 #endif /* 311 */

 int
 smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc;
 	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
 	unsigned char *sigptr = smb3_signature;
 	struct kvec *iov = rqst->rq_iov;
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[0].iov_base;
 	struct cifs_ses *ses;
 	struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
 	struct smb_rqst drqst;

 	ses = smb2_find_smb_ses(server, shdr->SessionId);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}

 	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
 	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

 	rc = crypto_shash_setkey(server->secmech.cmacaes,
 				 ses->smb3signingkey, SMB2_CMACAES_SIZE);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
 		return rc;
 	}

 	/*
 	 * we already allocate sdesccmacaes when we init smb3 signing key,
 	 * so unlike smb2 case we do not have to check here if secmech are
 	 * initialized
 	 */
 	rc = crypto_shash_init(shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
 		return rc;
 	}

 	/*
 	 * For SMB2+, __cifs_calc_signature() expects to sign only the actual
 	 * data, that is, iov[0] should not contain a rfc1002 length.
 	 *
 	 * Sign the rfc1002 length prior to passing the data (iov[1-N]) down to
 	 * __cifs_calc_signature().
 	 */
 	drqst = *rqst;
 	if (drqst.rq_nvec >= 2 && iov[0].iov_len == 4) {
 		rc = crypto_shash_update(shash, iov[0].iov_base,
 					 iov[0].iov_len);
 		if (rc) {
 			cifs_dbg(VFS, "%s: Could not update with payload\n",
 				 __func__);
 			return rc;
 		}
 		drqst.rq_iov++;
 		drqst.rq_nvec--;
 	}

 	rc = __cifs_calc_signature(&drqst, server, sigptr, shash);
 	if (!rc)
 		memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

 	return rc;
 }

 /* must be called with server->srv_mutex held */
 static int
 smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc = 0;
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;

 	if (!(shdr->Flags & SMB2_FLAGS_SIGNED) ||
 	    server->tcpStatus == CifsNeedNegotiate)
 		return rc;

 	if (!server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
 		return rc;
 	}

 	rc = server->ops->calc_signature(rqst, server);

 	return rc;
 }

 int
 smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	unsigned int rc;
 	char server_response_sig[16];
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;

 	if ((shdr->Command == SMB2_NEGOTIATE) ||
 	    (shdr->Command == SMB2_SESSION_SETUP) ||
 	    (shdr->Command == SMB2_OPLOCK_BREAK) ||
 	    (!server->session_estab))
 		return 0;

 	/*
 	 * BB what if signatures are supposed to be on for session but
 	 * server does not send one? BB
 	 */

 	/* Do not need to verify session setups with signature "BSRSPYL " */
 	if (memcmp(shdr->Signature, "BSRSPYL ", 8) == 0)
 		cifs_dbg(FYI, "dummy signature received for smb command 0x%x\n",
 			 shdr->Command);

 	/*
 	 * Save off the origiginal signature so we can modify the smb and check
 	 * our calculated signature against what the server sent.
 	 */
 	memcpy(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE);

 	memset(shdr->Signature, 0, SMB2_SIGNATURE_SIZE);

 	mutex_lock(&server->srv_mutex);
 	rc = server->ops->calc_signature(rqst, server);
 	mutex_unlock(&server->srv_mutex);

 	if (rc)
 		return rc;

 	if (memcmp(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE))
 		return -EACCES;
 	else
 		return 0;
 }

 /*
  * Set message id for the request. Should be called after wait_for_free_request
  * and when srv_mutex is held.
  */
 static inline void
 smb2_seq_num_into_buf(struct TCP_Server_Info *server,
 		      struct smb2_sync_hdr *shdr)
 {
 	unsigned int i, num = le16_to_cpu(shdr->CreditCharge);

 	shdr->MessageId = get_next_mid64(server);
 	/* skip message numbers according to CreditCharge field */
 	for (i = 1; i < num; i++)
 		get_next_mid(server);
 }

 static struct mid_q_entry *
 smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
 		     struct TCP_Server_Info *server)
 {
 	struct mid_q_entry *temp;

 	if (server == NULL) {
 		cifs_dbg(VFS, "Null TCP session in smb2_mid_entry_alloc\n");
 		return NULL;
 	}

 	temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
 	memset(temp, 0, sizeof(struct mid_q_entry));
 	kref_init(&temp->refcount);
 	temp->mid = le64_to_cpu(shdr->MessageId);
 	temp->pid = current->pid;
 	temp->command = shdr->Command; /* Always LE */
 	temp->when_alloc = jiffies;
 	temp->server = server;

 	/*
 	 * The default is for the mid to be synchronous, so the
 	 * default callback just wakes up the current task.
 	 */
 	temp->callback = cifs_wake_up_task;
 	temp->callback_data = current;

 	atomic_inc(&midCount);
 	temp->mid_state = MID_REQUEST_ALLOCATED;
 	return temp;
 }

 static int
 smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
 		   struct mid_q_entry **mid)
 {
 	if (ses->server->tcpStatus == CifsExiting)
 		return -ENOENT;

 	if (ses->server->tcpStatus == CifsNeedReconnect) {
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}

 	if (ses->status == CifsNew) {
 		if ((shdr->Command != SMB2_SESSION_SETUP) &&
 		    (shdr->Command != SMB2_NEGOTIATE))
 			return -EAGAIN;
 		/* else ok - we are setting up session */
 	}

 	if (ses->status == CifsExiting) {
 		if (shdr->Command != SMB2_LOGOFF)
 			return -EAGAIN;
 		/* else ok - we are shutting down the session */
 	}

 	*mid = smb2_mid_entry_alloc(shdr, ses->server);
 	if (*mid == NULL)
 		return -ENOMEM;
 	spin_lock(&GlobalMid_Lock);
 	list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
 	spin_unlock(&GlobalMid_Lock);
 	return 0;
 }

 int
 smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
 		   bool log_error)
 {
 	unsigned int len = mid->resp_buf_size;
 	struct kvec iov[1];
 	struct smb_rqst rqst = { .rq_iov = iov,
 				 .rq_nvec = 1 };

 	iov[0].iov_base = (char *)mid->resp_buf;
 	iov[0].iov_len = len;

 	dump_smb(mid->resp_buf, min_t(u32, 80, len));
 	/* convert the length into a more usable form */
 	if (len > 24 && server->sign && !mid->decrypted) {
 		int rc;

 		rc = smb2_verify_signature(&rqst, server);
 		if (rc)
 			cifs_dbg(VFS, "SMB signature verification returned error = %d\n",
 				 rc);
 	}

 	return map_smb2_to_linux_error(mid->resp_buf, log_error);
 }

 struct mid_q_entry *
 smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;

 	smb2_seq_num_into_buf(ses->server, shdr);

 	rc = smb2_get_mid_entry(ses, shdr, &mid);
 	if (rc)
 		return ERR_PTR(rc);
 	rc = smb2_sign_rqst(rqst, ses->server);
 	if (rc) {
 		cifs_delete_mid(mid);
 		return ERR_PTR(rc);
 	}
 	return mid;
 }

 struct mid_q_entry *
 smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 {
 	int rc;
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;

 	smb2_seq_num_into_buf(server, shdr);

 	mid = smb2_mid_entry_alloc(shdr, server);
 	if (mid == NULL)
 		return ERR_PTR(-ENOMEM);

 	rc = smb2_sign_rqst(rqst, server);
 	if (rc) {
 		DeleteMidQEntry(mid);
 		return ERR_PTR(rc);
 	}

 	return mid;
 }

 int
 smb3_crypto_aead_allocate(struct TCP_Server_Info *server)
 {
 	struct crypto_aead *tfm;

 	if (!server->secmech.ccmaesencrypt) {
 		tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
 		if (IS_ERR(tfm)) {
 			cifs_dbg(VFS, "%s: Failed to alloc encrypt aead\n",
 				 __func__);
 			return PTR_ERR(tfm);
 		}
 		server->secmech.ccmaesencrypt = tfm;
 	}

 	if (!server->secmech.ccmaesdecrypt) {
 		tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
 		if (IS_ERR(tfm)) {
 			crypto_free_aead(server->secmech.ccmaesencrypt);
 			server->secmech.ccmaesencrypt = NULL;
 			cifs_dbg(VFS, "%s: Failed to alloc decrypt aead\n",
 				 __func__);
 			return PTR_ERR(tfm);
 		}
 		server->secmech.ccmaesdecrypt = tfm;
 	}

 	return 0;
 }
	/*
	* fs/cifs/smb2transport.c
	*
	* Copyright (C) International Business Machines Corp., 2002, 2011
	* Etersoft, 2012
	* Author(s): Steve French (sfrench@us.ibm.com)
	* Jeremy Allison (jra@samba.org) 2006
	* Pavel Shilovsky (pshilovsky@samba.org) 2012
	*
	* This library is free software; you can redistribute it and/or modify
	* it under the terms of the GNU Lesser General Public License as published
	* by the Free Software Foundation; either version 2.1 of the License, or
	* (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
	* the GNU Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public License
	* along with this library; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/fs.h>
	#include <linux/list.h>
	#include <linux/wait.h>
	#include <linux/net.h>
	#include <linux/delay.h>
	#include <linux/uaccess.h>
	#include <asm/processor.h>
	#include <linux/mempool.h>
	#include <linux/highmem.h>
	#include <crypto/aead.h>
	#include "smb2pdu.h"
	#include "cifsglob.h"
	#include "cifsproto.h"
	#include "smb2proto.h"
	#include "cifs_debug.h"
	#include "smb2status.h"
	#include "smb2glob.h"

	static int
	smb2_crypto_shash_allocate(struct TCP_Server_Info *server)
	{
	return cifs_alloc_hash("hmac(sha256)",
	&server->secmech.hmacsha256,
	&server->secmech.sdeschmacsha256);
	}

	static int
	smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
	{
	struct cifs_secmech *p = &server->secmech;
	int rc;

	rc = cifs_alloc_hash("hmac(sha256)",
	&p->hmacsha256,
	&p->sdeschmacsha256);
	if (rc)
	goto err;

	rc = cifs_alloc_hash("cmac(aes)", &p->cmacaes, &p->sdesccmacaes);
	if (rc)
	goto err;

	return 0;
	err:
	cifs_free_hash(&p->hmacsha256, &p->sdeschmacsha256);
	return rc;
	}

	#ifdef CONFIG_CIFS_SMB311
	int
	smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
	{
	struct cifs_secmech *p = &server->secmech;
	int rc = 0;

	rc = cifs_alloc_hash("hmac(sha256)",
	&p->hmacsha256,
	&p->sdeschmacsha256);
	if (rc)
	return rc;

	rc = cifs_alloc_hash("cmac(aes)", &p->cmacaes, &p->sdesccmacaes);
	if (rc)
	goto err;

	rc = cifs_alloc_hash("sha512", &p->sha512, &p->sdescsha512);
	if (rc)
	goto err;

	return 0;

	err:
	cifs_free_hash(&p->cmacaes, &p->sdesccmacaes);
	cifs_free_hash(&p->hmacsha256, &p->sdeschmacsha256);
	return rc;
	}
	#endif

	static struct cifs_ses *
	smb2_find_smb_ses_unlocked(struct TCP_Server_Info *server, __u64 ses_id)
	{
	struct cifs_ses *ses;

	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
	if (ses->Suid != ses_id)
	continue;
	return ses;
	}

	return NULL;
	}

	struct cifs_ses *
	smb2_find_smb_ses(struct TCP_Server_Info *server, __u64 ses_id)
	{
	struct cifs_ses *ses;

	spin_lock(&cifs_tcp_ses_lock);
	ses = smb2_find_smb_ses_unlocked(server, ses_id);
	spin_unlock(&cifs_tcp_ses_lock);

	return ses;
	}

	static struct cifs_tcon *
	smb2_find_smb_sess_tcon_unlocked(struct cifs_ses *ses, __u32 tid)
	{
	struct cifs_tcon *tcon;

	list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
	if (tcon->tid != tid)
	continue;
	++tcon->tc_count;
	return tcon;
	}

	return NULL;
	}

	/*
	* Obtain tcon corresponding to the tid in the given
	* cifs_ses
	*/

	struct cifs_tcon *
	smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32 tid)
	{
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;

	spin_lock(&cifs_tcp_ses_lock);
	ses = smb2_find_smb_ses_unlocked(server, ses_id);
	if (!ses) {
	spin_unlock(&cifs_tcp_ses_lock);
	return NULL;
	}
	tcon = smb2_find_smb_sess_tcon_unlocked(ses, tid);
	spin_unlock(&cifs_tcp_ses_lock);

	return tcon;
	}

	int
	smb2_calc_signature(struct smb_rqst rqst, struct TCP_Server_Info server)
	{
	int rc;
	unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
	unsigned char *sigptr = smb2_signature;
	struct kvec *iov = rqst->rq_iov;
	struct smb2_sync_hdr shdr = (struct smb2_sync_hdr )iov[0].iov_base;
	struct cifs_ses *ses;
	struct shash_desc *shash = &server->secmech.sdeschmacsha256->shash;
	struct smb_rqst drqst;

	ses = smb2_find_smb_ses(server, shdr->SessionId);
	if (!ses) {
	cifs_dbg(VFS, "%s: Could not find session\n", __func__);
	return 0;
	}

	memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

	rc = smb2_crypto_shash_allocate(server);
	if (rc) {
	cifs_dbg(VFS, "%s: shah256 alloc failed\n", __func__);
	return rc;
	}

	rc = crypto_shash_setkey(server->secmech.hmacsha256,
	ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
	return rc;
	}

	rc = crypto_shash_init(shash);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not init sha256", __func__);
	return rc;
	}

	/*
	* For SMB2+, __cifs_calc_signature() expects to sign only the actual
	* data, that is, iov[0] should not contain a rfc1002 length.
	*
	* Sign the rfc1002 length prior to passing the data (iov[1-N]) down to
	* __cifs_calc_signature().
	*/
	drqst = *rqst;
	if (drqst.rq_nvec >= 2 && iov[0].iov_len == 4) {
	rc = crypto_shash_update(shash, iov[0].iov_base,
	iov[0].iov_len);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not update with payload\n",
	__func__);
	return rc;
	}
	drqst.rq_iov++;
	drqst.rq_nvec--;
	}

	rc = __cifs_calc_signature(&drqst, server, sigptr, shash);
	if (!rc)
	memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

	return rc;
	}

	static int generate_key(struct cifs_ses *ses, struct kvec label,
	struct kvec context, __u8 *key, unsigned int key_size)
	{
	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(key, 0x0, key_size);

	rc = smb3_crypto_shash_allocate(ses->server);
	if (rc) {
	cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
	goto smb3signkey_ret;
	}

	rc = crypto_shash_setkey(ses->server->secmech.hmacsha256,
	ses->auth_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(&ses->server->secmech.sdeschmacsha256->shash);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not init sign hmac\n", __func__);
	goto smb3signkey_ret;
	}

	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
	label.iov_base, label.iov_len);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
	goto smb3signkey_ret;
	}

	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
	context.iov_base, context.iov_len);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
	goto smb3signkey_ret;
	}

	rc = crypto_shash_update(&ses->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(&ses->server->secmech.sdeschmacsha256->shash,
	hashptr);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
	goto smb3signkey_ret;
	}

	memcpy(key, hashptr, key_size);

	smb3signkey_ret:
	return rc;
	}

	struct derivation {
	struct kvec label;
	struct kvec context;
	};

	struct derivation_triplet {
	struct derivation signing;
	struct derivation encryption;
	struct derivation decryption;
	};

	static int
	generate_smb3signingkey(struct cifs_ses *ses,
	const struct derivation_triplet *ptriplet)
	{
	int rc;

	rc = generate_key(ses, ptriplet->signing.label,
	ptriplet->signing.context, ses->smb3signingkey,
	SMB3_SIGN_KEY_SIZE);
	if (rc)
	return rc;

	rc = generate_key(ses, ptriplet->encryption.label,
	ptriplet->encryption.context, ses->smb3encryptionkey,
	SMB3_SIGN_KEY_SIZE);
	if (rc)
	return rc;

	rc = generate_key(ses, ptriplet->decryption.label,
	ptriplet->decryption.context,
	ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);

	if (rc)
	return rc;

	#ifdef CONFIG_CIFS_DEBUG_DUMP_KEYS
	cifs_dbg(VFS, "%s: dumping generated AES session keys\n", __func__);
	/*
	* The session id is opaque in terms of endianness, so we can't
	* print it as a long long. we dump it as we got it on the wire
	*/
	cifs_dbg(VFS, "Session Id %*ph\n", (int)sizeof(ses->Suid),
	&ses->Suid);
	cifs_dbg(VFS, "Session Key %*ph\n",
	SMB2_NTLMV2_SESSKEY_SIZE, ses->auth_key.response);
	cifs_dbg(VFS, "Signing Key %*ph\n",
	SMB3_SIGN_KEY_SIZE, ses->smb3signingkey);
	cifs_dbg(VFS, "ServerIn Key %*ph\n",
	SMB3_SIGN_KEY_SIZE, ses->smb3encryptionkey);
	cifs_dbg(VFS, "ServerOut Key %*ph\n",
	SMB3_SIGN_KEY_SIZE, ses->smb3decryptionkey);
	#endif
	return rc;
	}

	int
	generate_smb30signingkey(struct cifs_ses *ses)

	{
	struct derivation_triplet triplet;
	struct derivation *d;

	d = &triplet.signing;
	d->label.iov_base = "SMB2AESCMAC";
	d->label.iov_len = 12;
	d->context.iov_base = "SmbSign";
	d->context.iov_len = 8;

	d = &triplet.encryption;
	d->label.iov_base = "SMB2AESCCM";
	d->label.iov_len = 11;
	d->context.iov_base = "ServerIn ";
	d->context.iov_len = 10;

	d = &triplet.decryption;
	d->label.iov_base = "SMB2AESCCM";
	d->label.iov_len = 11;
	d->context.iov_base = "ServerOut";
	d->context.iov_len = 10;

	return generate_smb3signingkey(ses, &triplet);
	}

	#ifdef CONFIG_CIFS_SMB311
	int
	generate_smb311signingkey(struct cifs_ses *ses)

	{
	struct derivation_triplet triplet;
	struct derivation *d;

	d = &triplet.signing;
	d->label.iov_base = "SMBSigningKey";
	d->label.iov_len = 14;
	d->context.iov_base = ses->preauth_sha_hash;
	d->context.iov_len = 64;

	d = &triplet.encryption;
	d->label.iov_base = "SMBC2SCipherKey";
	d->label.iov_len = 16;
	d->context.iov_base = ses->preauth_sha_hash;
	d->context.iov_len = 64;

	d = &triplet.decryption;
	d->label.iov_base = "SMBS2CCipherKey";
	d->label.iov_len = 16;
	d->context.iov_base = ses->preauth_sha_hash;
	d->context.iov_len = 64;

	return generate_smb3signingkey(ses, &triplet);
	}
	#endif /* 311 */

	int
	smb3_calc_signature(struct smb_rqst rqst, struct TCP_Server_Info server)
	{
	int rc;
	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
	unsigned char *sigptr = smb3_signature;
	struct kvec *iov = rqst->rq_iov;
	struct smb2_sync_hdr shdr = (struct smb2_sync_hdr )iov[0].iov_base;
	struct cifs_ses *ses;
	struct shash_desc *shash = &server->secmech.sdesccmacaes->shash;
	struct smb_rqst drqst;

	ses = smb2_find_smb_ses(server, shdr->SessionId);
	if (!ses) {
	cifs_dbg(VFS, "%s: Could not find session\n", __func__);
	return 0;
	}

	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);

	rc = crypto_shash_setkey(server->secmech.cmacaes,
	ses->smb3signingkey, SMB2_CMACAES_SIZE);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
	return rc;
	}

	/*
	* we already allocate sdesccmacaes when we init smb3 signing key,
	* so unlike smb2 case we do not have to check here if secmech are
	* initialized
	*/
	rc = crypto_shash_init(shash);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
	return rc;
	}

	/*
	* For SMB2+, __cifs_calc_signature() expects to sign only the actual
	* data, that is, iov[0] should not contain a rfc1002 length.
	*
	* Sign the rfc1002 length prior to passing the data (iov[1-N]) down to
	* __cifs_calc_signature().
	*/
	drqst = *rqst;
	if (drqst.rq_nvec >= 2 && iov[0].iov_len == 4) {
	rc = crypto_shash_update(shash, iov[0].iov_base,
	iov[0].iov_len);
	if (rc) {
	cifs_dbg(VFS, "%s: Could not update with payload\n",
	__func__);
	return rc;
	}
	drqst.rq_iov++;
	drqst.rq_nvec--;
	}

	rc = __cifs_calc_signature(&drqst, server, sigptr, shash);
	if (!rc)
	memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);

	return rc;
	}

	/* must be called with server->srv_mutex held */
	static int
	smb2_sign_rqst(struct smb_rqst rqst, struct TCP_Server_Info server)
	{
	int rc = 0;
	struct smb2_sync_hdr *shdr =
	(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;

	if (!(shdr->Flags & SMB2_FLAGS_SIGNED) \|\|
	server->tcpStatus == CifsNeedNegotiate)
	return rc;

	if (!server->session_estab) {
	strncpy(shdr->Signature, "BSRSPYL", 8);
	return rc;
	}

	rc = server->ops->calc_signature(rqst, server);

	return rc;
	}

	int
	smb2_verify_signature(struct smb_rqst rqst, struct TCP_Server_Info server)
	{
	unsigned int rc;
	char server_response_sig[16];
	struct smb2_sync_hdr *shdr =
	(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;

	if ((shdr->Command == SMB2_NEGOTIATE) \|\|
	(shdr->Command == SMB2_SESSION_SETUP) \|\|
	(shdr->Command == SMB2_OPLOCK_BREAK) \|\|
	(!server->session_estab))
	return 0;

	/*
	* BB what if signatures are supposed to be on for session but
	* server does not send one? BB
	*/

	/* Do not need to verify session setups with signature "BSRSPYL " */
	if (memcmp(shdr->Signature, "BSRSPYL ", 8) == 0)
	cifs_dbg(FYI, "dummy signature received for smb command 0x%x\n",
	shdr->Command);

	/*
	* Save off the origiginal signature so we can modify the smb and check
	* our calculated signature against what the server sent.
	*/
	memcpy(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE);

	memset(shdr->Signature, 0, SMB2_SIGNATURE_SIZE);

	mutex_lock(&server->srv_mutex);
	rc = server->ops->calc_signature(rqst, server);
	mutex_unlock(&server->srv_mutex);

	if (rc)
	return rc;

	if (memcmp(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE))
	return -EACCES;
	else
	return 0;
	}

	/*
	* Set message id for the request. Should be called after wait_for_free_request
	* and when srv_mutex is held.
	*/
	static inline void
	smb2_seq_num_into_buf(struct TCP_Server_Info *server,
	struct smb2_sync_hdr *shdr)
	{
	unsigned int i, num = le16_to_cpu(shdr->CreditCharge);

	shdr->MessageId = get_next_mid64(server);
	/* skip message numbers according to CreditCharge field */
	for (i = 1; i < num; i++)
	get_next_mid(server);
	}

	static struct mid_q_entry *
	smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
	struct TCP_Server_Info *server)
	{
	struct mid_q_entry *temp;

	if (server == NULL) {
	cifs_dbg(VFS, "Null TCP session in smb2_mid_entry_alloc\n");
	return NULL;
	}

	temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
	memset(temp, 0, sizeof(struct mid_q_entry));
	kref_init(&temp->refcount);
	temp->mid = le64_to_cpu(shdr->MessageId);
	temp->pid = current->pid;
	temp->command = shdr->Command; /* Always LE */
	temp->when_alloc = jiffies;
	temp->server = server;

	/*
	* The default is for the mid to be synchronous, so the
	* default callback just wakes up the current task.
	*/
	temp->callback = cifs_wake_up_task;
	temp->callback_data = current;

	atomic_inc(&midCount);
	temp->mid_state = MID_REQUEST_ALLOCATED;
	return temp;
	}

	static int
	smb2_get_mid_entry(struct cifs_ses ses, struct smb2_sync_hdr shdr,
	struct mid_q_entry **mid)
	{
	if (ses->server->tcpStatus == CifsExiting)
	return -ENOENT;

	if (ses->server->tcpStatus == CifsNeedReconnect) {
	cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
	return -EAGAIN;
	}

	if (ses->status == CifsNew) {
	if ((shdr->Command != SMB2_SESSION_SETUP) &&
	(shdr->Command != SMB2_NEGOTIATE))
	return -EAGAIN;
	/* else ok - we are setting up session */
	}

	if (ses->status == CifsExiting) {
	if (shdr->Command != SMB2_LOGOFF)
	return -EAGAIN;
	/* else ok - we are shutting down the session */
	}

	*mid = smb2_mid_entry_alloc(shdr, ses->server);
	if (*mid == NULL)
	return -ENOMEM;
	spin_lock(&GlobalMid_Lock);
	list_add_tail(&(*mid)->qhead, &ses->server->pending_mid_q);
	spin_unlock(&GlobalMid_Lock);
	return 0;
	}

	int
	smb2_check_receive(struct mid_q_entry mid, struct TCP_Server_Info server,
	bool log_error)
	{
	unsigned int len = mid->resp_buf_size;
	struct kvec iov[1];
	struct smb_rqst rqst = { .rq_iov = iov,
	.rq_nvec = 1 };

	iov[0].iov_base = (char *)mid->resp_buf;
	iov[0].iov_len = len;

	dump_smb(mid->resp_buf, min_t(u32, 80, len));
	/* convert the length into a more usable form */
	if (len > 24 && server->sign && !mid->decrypted) {
	int rc;

	rc = smb2_verify_signature(&rqst, server);
	if (rc)
	cifs_dbg(VFS, "SMB signature verification returned error = %d\n",
	rc);
	}

	return map_smb2_to_linux_error(mid->resp_buf, log_error);
	}

	struct mid_q_entry *
	smb2_setup_request(struct cifs_ses ses, struct smb_rqst rqst)
	{
	int rc;
	struct smb2_sync_hdr *shdr =
	(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
	struct mid_q_entry *mid;

	smb2_seq_num_into_buf(ses->server, shdr);

	rc = smb2_get_mid_entry(ses, shdr, &mid);
	if (rc)
	return ERR_PTR(rc);
	rc = smb2_sign_rqst(rqst, ses->server);
	if (rc) {
	cifs_delete_mid(mid);
	return ERR_PTR(rc);
	}
	return mid;
	}

	struct mid_q_entry *
	smb2_setup_async_request(struct TCP_Server_Info server, struct smb_rqst rqst)
	{
	int rc;
	struct smb2_sync_hdr *shdr =
	(struct smb2_sync_hdr *)rqst->rq_iov[0].iov_base;
	struct mid_q_entry *mid;

	smb2_seq_num_into_buf(server, shdr);

	mid = smb2_mid_entry_alloc(shdr, server);
	if (mid == NULL)
	return ERR_PTR(-ENOMEM);

	rc = smb2_sign_rqst(rqst, server);
	if (rc) {
	DeleteMidQEntry(mid);
	return ERR_PTR(rc);
	}

	return mid;
	}

	int
	smb3_crypto_aead_allocate(struct TCP_Server_Info *server)
	{
	struct crypto_aead *tfm;

	if (!server->secmech.ccmaesencrypt) {
	tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
	if (IS_ERR(tfm)) {
	cifs_dbg(VFS, "%s: Failed to alloc encrypt aead\n",
	__func__);
	return PTR_ERR(tfm);
	}
	server->secmech.ccmaesencrypt = tfm;
	}

	if (!server->secmech.ccmaesdecrypt) {
	tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
	if (IS_ERR(tfm)) {
	crypto_free_aead(server->secmech.ccmaesencrypt);
	server->secmech.ccmaesencrypt = NULL;
	cifs_dbg(VFS, "%s: Failed to alloc decrypt aead\n",
	__func__);
	return PTR_ERR(tfm);
	}
	server->secmech.ccmaesdecrypt = tfm;
	}

	return 0;
	}