CIFS: Encrypt SMB3 requests before sending

BugLink: http://bugs.launchpad.net/bugs/1670508

This change allows to encrypt packets if it is required by a server
for SMB sessions or tree connections.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
(backported from commit 026e93dc)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>

fs/cifs/Kconfig

@@ -174,6 +174,8 @@ config CIFS_SMB2
 	select CRYPTO_AES
 	select CRYPTO_SHA256
 	select CRYPTO_CMAC
+	select CRYPTO_AEAD2
+	select CRYPTO_CCM
 
 	help
 	  This enables support for the Server Message Block version 2

fs/cifs/cifsencrypt.c

@@ -33,6 +33,7 @@
 #include <linux/ctype.h>
 #include <linux/random.h>
 #include <linux/highmem.h>
+#include <crypto/aead.h>
 
 static int
 cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
@@ -855,7 +856,7 @@ calc_seckey(struct cifs_ses *ses)
 }
 
 void
-cifs_crypto_shash_release(struct TCP_Server_Info *server)
+cifs_crypto_secmech_release(struct TCP_Server_Info *server)
 {
 	if (server->secmech.cmacaes) {
 		crypto_free_shash(server->secmech.cmacaes);
@@ -877,6 +878,16 @@ cifs_crypto_shash_release(struct TCP_Server_Info *server)
 		server->secmech.hmacmd5 = NULL;
 	}
 
+	if (server->secmech.ccmaesencrypt) {
+		crypto_free_aead(server->secmech.ccmaesencrypt);
+		server->secmech.ccmaesencrypt = NULL;
+	}
+
+	if (server->secmech.ccmaesdecrypt) {
+		crypto_free_aead(server->secmech.ccmaesdecrypt);
+		server->secmech.ccmaesdecrypt = NULL;
+	}
+
 	kfree(server->secmech.sdesccmacaes);
 	server->secmech.sdesccmacaes = NULL;
 	kfree(server->secmech.sdeschmacsha256);

fs/cifs/cifsfs.c

@@ -1319,6 +1319,8 @@ MODULE_SOFTDEP("pre: nls");
 MODULE_SOFTDEP("pre: aes");
 MODULE_SOFTDEP("pre: cmac");
 MODULE_SOFTDEP("pre: sha256");
+MODULE_SOFTDEP("pre: aead2");
+MODULE_SOFTDEP("pre: ccm");
 #endif /* CONFIG_CIFS_SMB2 */
 module_init(init_cifs)
 module_exit(exit_cifs)

fs/cifs/cifsglob.h

@@ -136,6 +136,8 @@ struct cifs_secmech {
 	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 */
+	struct crypto_aead *ccmaesencrypt; /* smb3 encryption aead */
+	struct crypto_aead *ccmaesdecrypt; /* smb3 decryption aead */
 };
 
 /* per smb session structure/fields */

fs/cifs/cifsproto.h

@@ -443,7 +443,7 @@ extern int SMBNTencrypt(unsigned char *, unsigned char *, unsigned char *,
 			const struct nls_table *);
 extern int setup_ntlm_response(struct cifs_ses *, const struct nls_table *);
 extern int setup_ntlmv2_rsp(struct cifs_ses *, const struct nls_table *);
-extern void cifs_crypto_shash_release(struct TCP_Server_Info *);
+extern void cifs_crypto_secmech_release(struct TCP_Server_Info *server);
 extern int calc_seckey(struct cifs_ses *);
 extern int generate_smb30signingkey(struct cifs_ses *);
 extern int generate_smb311signingkey(struct cifs_ses *);

fs/cifs/connect.c

@@ -2127,7 +2127,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 	server->tcpStatus = CifsExiting;
 	spin_unlock(&GlobalMid_Lock);
 
-	cifs_crypto_shash_release(server);
+	cifs_crypto_secmech_release(server);
 	cifs_fscache_release_client_cookie(server);
 
 	kfree(server->session_key.response);
@@ -2246,7 +2246,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	return tcp_ses;
 
 out_err_crypto_release:
-	cifs_crypto_shash_release(tcp_ses);
+	cifs_crypto_secmech_release(tcp_ses);
 
 	put_net(cifs_net_ns(tcp_ses));
 

fs/cifs/smb2ops.c

@@ -20,6 +20,8 @@
 #include <linux/pagemap.h>
 #include <linux/vfs.h>
 #include <linux/falloc.h>
+#include <linux/scatterlist.h>
+#include <crypto/aead.h>
 #include "cifsglob.h"
 #include "smb2pdu.h"
 #include "smb2proto.h"
@@ -1502,6 +1504,256 @@ smb2_dir_needs_close(struct cifsFileInfo *cfile)
 	return !cfile->invalidHandle;
 }
 
+static void
+fill_transform_hdr(struct smb2_transform_hdr *tr_hdr, struct smb_rqst *old_rq)
+{
+	struct smb2_sync_hdr *shdr =
+			(struct smb2_sync_hdr *)old_rq->rq_iov[1].iov_base;
+	unsigned int orig_len = get_rfc1002_length(old_rq->rq_iov[0].iov_base);
+
+	memset(tr_hdr, 0, sizeof(struct smb2_transform_hdr));
+	tr_hdr->ProtocolId = SMB2_TRANSFORM_PROTO_NUM;
+	tr_hdr->OriginalMessageSize = cpu_to_le32(orig_len);
+	tr_hdr->Flags = cpu_to_le16(0x01);
+	get_random_bytes(&tr_hdr->Nonce, SMB3_AES128CMM_NONCE);
+	memcpy(&tr_hdr->SessionId, &shdr->SessionId, 8);
+	inc_rfc1001_len(tr_hdr, sizeof(struct smb2_transform_hdr) - 4);
+	inc_rfc1001_len(tr_hdr, orig_len);
+}
+
+static struct scatterlist *
+init_sg(struct smb_rqst *rqst, u8 *sign)
+{
+	unsigned int sg_len = rqst->rq_nvec + rqst->rq_npages + 1;
+	unsigned int assoc_data_len = sizeof(struct smb2_transform_hdr) - 24;
+	struct scatterlist *sg;
+	unsigned int i;
+	unsigned int j;
+
+	sg = kmalloc_array(sg_len, sizeof(struct scatterlist), GFP_KERNEL);
+	if (!sg)
+		return NULL;
+
+	sg_init_table(sg, sg_len);
+	sg_set_buf(&sg[0], rqst->rq_iov[0].iov_base + 24, assoc_data_len);
+	for (i = 1; i < rqst->rq_nvec; i++)
+		sg_set_buf(&sg[i], rqst->rq_iov[i].iov_base,
+						rqst->rq_iov[i].iov_len);
+	for (j = 0; i < sg_len - 1; i++, j++) {
+		unsigned int len = (j < rqst->rq_npages - 1) ? rqst->rq_pagesz
+							: rqst->rq_tailsz;
+		sg_set_page(&sg[i], rqst->rq_pages[j], len, 0);
+	}
+	sg_set_buf(&sg[sg_len - 1], sign, SMB2_SIGNATURE_SIZE);
+	return sg;
+}
+
+struct cifs_crypt_result {
+	int err;
+	struct completion completion;
+};
+
+static void cifs_crypt_complete(struct crypto_async_request *req, int err)
+{
+	struct cifs_crypt_result *res = req->data;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	res->err = err;
+	complete(&res->completion);
+}
+
+/*
+ * Encrypt or decrypt @rqst message. @rqst has the following format:
+ * iov[0] - transform header (associate data),
+ * iov[1-N] and pages - data to encrypt.
+ * On success return encrypted data in iov[1-N] and pages, leave iov[0]
+ * untouched.
+ */
+static int
+crypt_message(struct TCP_Server_Info *server, struct smb_rqst *rqst, int enc)
+{
+	struct smb2_transform_hdr *tr_hdr =
+			(struct smb2_transform_hdr *)rqst->rq_iov[0].iov_base;
+	unsigned int assoc_data_len = sizeof(struct smb2_transform_hdr) - 24;
+	struct cifs_ses *ses;
+	int rc = 0;
+	struct scatterlist *sg;
+	u8 sign[SMB2_SIGNATURE_SIZE] = {};
+	struct aead_request *req;
+	char *iv;
+	unsigned int iv_len;
+	struct cifs_crypt_result result = {0, };
+	struct crypto_aead *tfm;
+	unsigned int crypt_len = le32_to_cpu(tr_hdr->OriginalMessageSize);
+
+	init_completion(&result.completion);
+
+	ses = smb2_find_smb_ses(server, tr_hdr->SessionId);
+	if (!ses) {
+		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
+		return 0;
+	}
+
+	rc = smb3_crypto_aead_allocate(server);
+	if (rc) {
+		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
+		return rc;
+	}
+
+	tfm = enc ? server->secmech.ccmaesencrypt :
+						server->secmech.ccmaesdecrypt;
+	rc = crypto_aead_setkey(tfm, enc ? ses->smb3encryptionkey :
+				ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
+	if (rc) {
+		cifs_dbg(VFS, "%s: Failed to set aead key %d\n", __func__, rc);
+		return rc;
+	}
+
+	rc = crypto_aead_setauthsize(tfm, SMB2_SIGNATURE_SIZE);
+	if (rc) {
+		cifs_dbg(VFS, "%s: Failed to set authsize %d\n", __func__, rc);
+		return rc;
+	}
+
+	req = aead_request_alloc(tfm, GFP_KERNEL);
+	if (!req) {
+		cifs_dbg(VFS, "%s: Failed to alloc aead request", __func__);
+		return -ENOMEM;
+	}
+
+	if (!enc) {
+		memcpy(sign, &tr_hdr->Signature, SMB2_SIGNATURE_SIZE);
+		crypt_len += SMB2_SIGNATURE_SIZE;
+	}
+
+	sg = init_sg(rqst, sign);
+	if (!sg) {
+		cifs_dbg(VFS, "%s: Failed to init sg %d", __func__, rc);
+		goto free_req;
+	}
+
+	iv_len = crypto_aead_ivsize(tfm);
+	iv = kzalloc(iv_len, GFP_KERNEL);
+	if (!iv) {
+		cifs_dbg(VFS, "%s: Failed to alloc IV", __func__);
+		goto free_sg;
+	}
+	iv[0] = 3;
+	memcpy(iv + 1, (char *)tr_hdr->Nonce, SMB3_AES128CMM_NONCE);
+
+	aead_request_set_crypt(req, sg, sg, crypt_len, iv);
+	aead_request_set_ad(req, assoc_data_len);
+
+	aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				  cifs_crypt_complete, &result);
+
+	rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req);
+
+	if (rc == -EINPROGRESS || rc == -EBUSY) {
+		wait_for_completion(&result.completion);
+		rc = result.err;
+	}
+
+	if (!rc && enc)
+		memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE);
+
+	kfree(iv);
+free_sg:
+	kfree(sg);
+free_req:
+	kfree(req);
+	return rc;
+}
+
+static int
+smb3_init_transform_rq(struct TCP_Server_Info *server, struct smb_rqst *new_rq,
+		       struct smb_rqst *old_rq)
+{
+	struct kvec *iov;
+	struct page **pages;
+	struct smb2_transform_hdr *tr_hdr;
+	unsigned int npages = old_rq->rq_npages;
+	int i;
+	int rc = -ENOMEM;
+
+	pages = kmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		return rc;
+
+	new_rq->rq_pages = pages;
+	new_rq->rq_npages = old_rq->rq_npages;
+	new_rq->rq_pagesz = old_rq->rq_pagesz;
+	new_rq->rq_tailsz = old_rq->rq_tailsz;
+
+	for (i = 0; i < npages; i++) {
+		pages[i] = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
+		if (!pages[i])
+			goto err_free_pages;
+	}
+
+	iov = kmalloc_array(old_rq->rq_nvec, sizeof(struct kvec), GFP_KERNEL);
+	if (!iov)
+		goto err_free_pages;
+
+	/* copy all iovs from the old except the 1st one (rfc1002 length) */
+	memcpy(&iov[1], &old_rq->rq_iov[1],
+				sizeof(struct kvec) * (old_rq->rq_nvec - 1));
+	new_rq->rq_iov = iov;
+	new_rq->rq_nvec = old_rq->rq_nvec;
+
+	tr_hdr = kmalloc(sizeof(struct smb2_transform_hdr), GFP_KERNEL);
+	if (!tr_hdr)
+		goto err_free_iov;
+
+	/* fill the 1st iov with a transform header */
+	fill_transform_hdr(tr_hdr, old_rq);
+	new_rq->rq_iov[0].iov_base = tr_hdr;
+	new_rq->rq_iov[0].iov_len = sizeof(struct smb2_transform_hdr);
+
+	/* copy pages form the old */
+	for (i = 0; i < npages; i++) {
+		char *dst = kmap(new_rq->rq_pages[i]);
+		char *src = kmap(old_rq->rq_pages[i]);
+		unsigned int len = (i < npages - 1) ? new_rq->rq_pagesz :
+							new_rq->rq_tailsz;
+		memcpy(dst, src, len);
+		kunmap(new_rq->rq_pages[i]);
+		kunmap(old_rq->rq_pages[i]);
+	}
+
+	rc = crypt_message(server, new_rq, 1);
+	cifs_dbg(FYI, "encrypt message returned %d", rc);
+	if (rc)
+		goto err_free_tr_hdr;
+
+	return rc;
+
+err_free_tr_hdr:
+	kfree(tr_hdr);
+err_free_iov:
+	kfree(iov);
+err_free_pages:
+	for (i = i - 1; i >= 0; i--)
+		put_page(pages[i]);
+	kfree(pages);
+	return rc;
+}
+
+static void
+smb3_free_transform_rq(struct smb_rqst *rqst)
+{
+	int i = rqst->rq_npages - 1;
+
+	for (; i >= 0; i--)
+		put_page(rqst->rq_pages[i]);
+	kfree(rqst->rq_pages);
+	/* free transform header */
+	kfree(rqst->rq_iov[0].iov_base);
+	kfree(rqst->rq_iov);
+}
+
 struct smb_version_operations smb20_operations = {
 	.compare_fids = smb2_compare_fids,
 	.setup_request = smb2_setup_request,
@@ -1744,6 +1996,8 @@ struct smb_version_operations smb30_operations = {
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
 	.fallocate = smb3_fallocate,
+	.init_transform_rq = smb3_init_transform_rq,
+	.free_transform_rq = smb3_free_transform_rq,
 };
 
 #ifdef CONFIG_CIFS_SMB311
@@ -1831,6 +2085,8 @@ struct smb_version_operations smb311_operations = {
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
 	.fallocate = smb3_fallocate,
+	.init_transform_rq = smb3_init_transform_rq,
+	.free_transform_rq = smb3_free_transform_rq,
 };
 #endif /* CIFS_SMB311 */
 

fs/cifs/smb2pdu.h

@@ -132,11 +132,14 @@ struct smb2_pdu {
 	__le16 StructureSize2; /* size of wct area (varies, request specific) */
 } __packed;
 
+#define SMB3_AES128CMM_NONCE 11
+#define SMB3_AES128GCM_NONCE 12
+
 struct smb2_transform_hdr {
 	__be32 smb2_buf_length;	/* big endian on wire */
 				/* length is only two or three bytes - with
 				 one or two byte type preceding it that MBZ */
-	__u8   ProtocolId[4];	/* 0xFD 'S' 'M' 'B' */
+	__le32 ProtocolId;	/* 0xFD 'S' 'M' 'B' */
 	__u8   Signature[16];
 	__u8   Nonce[16];
 	__le32 OriginalMessageSize;

fs/cifs/smb2proto.h

@@ -56,6 +56,8 @@ extern void smb2_echo_request(struct work_struct *work);
 extern __le32 smb2_get_lease_state(struct cifsInodeInfo *cinode);
 extern bool smb2_is_valid_oplock_break(char *buffer,
 				       struct TCP_Server_Info *srv);
+extern struct cifs_ses *smb2_find_smb_ses(struct TCP_Server_Info *server,
+					  __u64 ses_id);
 
 extern void move_smb2_info_to_cifs(FILE_ALL_INFO *dst,
 				   struct smb2_file_all_info *src);
@@ -97,6 +99,7 @@ extern int smb2_unlock_range(struct cifsFileInfo *cfile,
 			     struct file_lock *flock, const unsigned int xid);
 extern int smb2_push_mandatory_locks(struct cifsFileInfo *cfile);
 extern void smb2_reconnect_server(struct work_struct *work);
+extern int smb3_crypto_aead_allocate(struct TCP_Server_Info *server);
 
 /*
  * SMB2 Worker functions - most of protocol specific implementation details

fs/cifs/smb2transport.c

@@ -31,6 +31,7 @@
 #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"
@@ -114,14 +115,14 @@ smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 	return 0;
 }
 
-static struct cifs_ses *
-smb2_find_smb_ses(struct smb2_sync_hdr *shdr, struct TCP_Server_Info *server)
+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);
 	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
-		if (ses->Suid != shdr->SessionId)
+		if (ses->Suid != ses_id)
 			continue;
 		spin_unlock(&cifs_tcp_ses_lock);
 		return ses;
@@ -141,7 +142,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[1].iov_base;
 	struct cifs_ses *ses;
 
-	ses = smb2_find_smb_ses(shdr, server);
+	ses = smb2_find_smb_ses(server, shdr->SessionId);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
@@ -358,7 +359,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[1].iov_base;
 	struct cifs_ses *ses;
 
-	ses = smb2_find_smb_ses(shdr, server);
+	ses = smb2_find_smb_ses(server, shdr->SessionId);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
@@ -618,3 +619,33 @@ smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 
 	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;
+}