From 373512ec5c105ed09e3738196dcb257dfab65cba Mon Sep 17 00:00:00 2001
From: Steve French <smfrench@gmail.com>
Date: Fri, 18 Dec 2015 13:05:30 -0600
Subject: Prepare for encryption support (first part). Add decryption and
 encryption key generation. Thanks to Metze for helping with this.

Reviewed-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <steve.french@primarydata.com>
---
 fs/cifs/smb2transport.c | 102 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 96 insertions(+), 6 deletions(-)

(limited to 'fs/cifs/smb2transport.c')

diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index d4c5b6f109a7..8732a43b1008 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -222,8 +222,8 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	return rc;
 }
 
-int
-generate_smb3signingkey(struct cifs_ses *ses)
+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};
@@ -233,7 +233,7 @@ generate_smb3signingkey(struct cifs_ses *ses)
 	unsigned char *hashptr = prfhash;
 
 	memset(prfhash, 0x0, SMB2_HMACSHA256_SIZE);
-	memset(ses->smb3signingkey, 0x0, SMB3_SIGNKEY_SIZE);
+	memset(key, 0x0, key_size);
 
 	rc = smb3_crypto_shash_allocate(ses->server);
 	if (rc) {
@@ -262,7 +262,7 @@ generate_smb3signingkey(struct cifs_ses *ses)
 	}
 
 	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
-				"SMB2AESCMAC", 12);
+				label.iov_base, label.iov_len);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
 		goto smb3signkey_ret;
@@ -276,7 +276,7 @@ generate_smb3signingkey(struct cifs_ses *ses)
 	}
 
 	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
-				"SmbSign", 8);
+				context.iov_base, context.iov_len);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
 		goto smb3signkey_ret;
@@ -296,12 +296,102 @@ generate_smb3signingkey(struct cifs_ses *ses)
 		goto smb3signkey_ret;
 	}
 
-	memcpy(ses->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
+	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;
+
+	return generate_key(ses, ptriplet->decryption.label,
+			    ptriplet->decryption.context,
+			    ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
+}
+
+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);
+}
+
+int
+generate_smb311signingkey(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);
+}
+
 int
 smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
-- 
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