From: Steve French <stfrench@microsoft.com>
Date: Sat, 19 May 2018 20:45:27 -0500
Subject: [PATCH] smb3: add support for posix negotiate context
Git-commit: fcef0db6d630ccadaa65138b77eac5fce16a13c9
Patch-mainline: v4.17
References: bsc#1144333

Unlike CIFS where UNIX/POSIX extensions had been negotiatable,
SMB3 did not have POSIX extensions yet.  Add the new SMB3.11
POSIX negotiate context to ask the server whether it can
support POSIX (and thus whether we can send the new POSIX open
context).

Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifs_debug.c |  4 ++++
 fs/cifs/cifsglob.h   |  1 +
 fs/cifs/smb2pdu.c    | 29 +++++++++++++++++++++++------
 fs/cifs/smb2pdu.h    |  8 ++++++++
 4 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 7b857002c063..842b198d8516 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -238,6 +238,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			server->credits,  server->dialect);
 		if (server->sign)
 			seq_printf(m, " signed");
+#ifdef CONFIG_CIFS_SMB311
+		if (server->posix_ext_supported)
+			seq_printf(m, " posix");
+#endif /* 3.1.1 */
 		i++;
 		list_for_each(tmp2, &server->smb_ses_list) {
 			ses = list_entry(tmp2, struct cifs_ses,
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d2ac9ced28c9..b131a395b95c 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -683,6 +683,7 @@ struct TCP_Server_Info {
 	__le16	cipher_type;
 	 /* save initital negprot hash */
 	__u8	preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
+	bool	posix_ext_supported;
 #endif /* 3.1.1 */
 	struct delayed_work reconnect; /* reconnect workqueue job */
 	struct mutex reconnect_mutex; /* prevent simultaneous reconnects */
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index a02f6b674d0f..5e947db322a7 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -368,6 +368,7 @@ smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,
 
 #define SMB2_PREAUTH_INTEGRITY_CAPABILITIES	cpu_to_le16(1)
 #define SMB2_ENCRYPTION_CAPABILITIES		cpu_to_le16(2)
+#define SMB2_POSIX_EXTENSIONS_AVAILABLE		cpu_to_le16(0x100)
 
 static void
 build_preauth_ctxt(struct smb2_preauth_neg_context *pneg_ctxt)
@@ -390,22 +391,36 @@ build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
 	pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_CCM;
 }
 
+static void
+build_posix_ctxt(struct smb2_posix_neg_context *pneg_ctxt)
+{
+	pneg_ctxt->ContextType = SMB2_POSIX_EXTENSIONS_AVAILABLE;
+	pneg_ctxt->DataLength = cpu_to_le16(POSIX_CTXT_DATA_LEN);
+}
+
 static void
 assemble_neg_contexts(struct smb2_negotiate_req *req,
 		      unsigned int *total_len)
 {
 	char *pneg_ctxt = (char *)req + OFFSET_OF_NEG_CONTEXT;
+	unsigned int ctxt_len;
 
+	*total_len += 2; /* Add 2 due to round to 8 byte boundary for 1st ctxt */
 	build_preauth_ctxt((struct smb2_preauth_neg_context *)pneg_ctxt);
-	/* Add 2 to size to round to 8 byte boundary */
+	ctxt_len = DIV_ROUND_UP(sizeof(struct smb2_preauth_neg_context), 8) * 8;
+	*total_len += ctxt_len;
+	pneg_ctxt += ctxt_len;
 
-	pneg_ctxt += 2 + sizeof(struct smb2_preauth_neg_context);
 	build_encrypt_ctxt((struct smb2_encryption_neg_context *)pneg_ctxt);
-	req->NegotiateContextOffset = cpu_to_le32(OFFSET_OF_NEG_CONTEXT);
-	req->NegotiateContextCount = cpu_to_le16(2);
+	ctxt_len = DIV_ROUND_UP(sizeof(struct smb2_encryption_neg_context), 8) * 8;
+	*total_len += ctxt_len;
+	pneg_ctxt += ctxt_len;
+
+	build_posix_ctxt((struct smb2_posix_neg_context *)pneg_ctxt);
+	*total_len += sizeof(struct smb2_posix_neg_context);
 
-	*total_len += 4 + sizeof(struct smb2_preauth_neg_context)
-		+ sizeof(struct smb2_encryption_neg_context);
+	req->NegotiateContextOffset = cpu_to_le32(OFFSET_OF_NEG_CONTEXT);
+	req->NegotiateContextCount = cpu_to_le16(3);
 }
 
 static void decode_preauth_context(struct smb2_preauth_neg_context *ctxt)
@@ -488,6 +503,8 @@ static int smb311_decode_neg_context(struct smb2_negotiate_rsp *rsp,
 		else if (pctx->ContextType == SMB2_ENCRYPTION_CAPABILITIES)
 			rc = decode_encrypt_ctx(server,
 				(struct smb2_encryption_neg_context *)pctx);
+		else if (pctx->ContextType == SMB2_POSIX_EXTENSIONS_AVAILABLE)
+			server->posix_ext_supported = true;
 		else
 			cifs_dbg(VFS, "unknown negcontext of type %d ignored\n",
 				le16_to_cpu(pctx->ContextType));
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index d28f358022c5..853e5a707276 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -300,6 +300,14 @@ struct smb2_encryption_neg_context {
 	__le16	Ciphers[1]; /* Ciphers[0] since only one used now */
 } __packed;
 
+#define POSIX_CTXT_DATA_LEN	8
+struct smb2_posix_neg_context {
+	__le16	ContextType; /* 0x100 */
+	__le16	DataLength;
+	__le32	Reserved;
+	__le64	Reserved1; /* In case needed for future (eg version or caps) */
+} __packed;
+
 struct smb2_negotiate_rsp {
 	struct smb2_hdr hdr;
 	__le16 StructureSize;	/* Must be 65 */
-- 
2.16.4