ksmbd: remove unused compression negotiate ctx packing

build_compression_ctxt() is currently unreachable due to
conn.compress_algorithm remaining zero (SMB3_COMPRESS_NONE).

It appears to have been broken in a couple of subtle ways over the
years:
- prior to d6c9ad23b421 ("ksmbd: use the common definitions for
  NEGOTIATE_PROTOCOL") smb2_compression_ctx.DataLength was set to 8,
  which didn't account for the single CompressionAlgorithms flexible
  array member.
- post d6c9ad23b421 smb2_compression_capabilities_context
  CompressionAlgorithms is a three member array, while
  CompressionAlgorithmCount is set to indicate only one member.
  assemble_neg_contexts() ctxt_size is also incorrectly incremented by
  sizeof(struct smb2_compression_capabilities_context) + 2, which
  assumes one flexible array member.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 8578091..215fea2 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -756,19 +756,6 @@ static void build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt,
        pneg_ctxt->Ciphers[0] = cipher_type;
 }
 
-static void build_compression_ctxt(struct smb2_compression_capabilities_context *pneg_ctxt,
-                                  __le16 comp_algo)
-{
-       pneg_ctxt->ContextType = SMB2_COMPRESSION_CAPABILITIES;
-       pneg_ctxt->DataLength =
-               cpu_to_le16(sizeof(struct smb2_compression_capabilities_context)
-                       - sizeof(struct smb2_neg_context));
-       pneg_ctxt->Reserved = cpu_to_le32(0);
-       pneg_ctxt->CompressionAlgorithmCount = cpu_to_le16(1);
-       pneg_ctxt->Flags = cpu_to_le32(0);
-       pneg_ctxt->CompressionAlgorithms[0] = comp_algo;
-}
-
 static void build_sign_cap_ctxt(struct smb2_signing_capabilities *pneg_ctxt,
                                __le16 sign_algo)
 {
@@ -832,17 +819,8 @@ static void assemble_neg_contexts(struct ksmbd_conn *conn,
                ctxt_size += sizeof(struct smb2_encryption_neg_context) + 2;
        }
 
-       if (conn->compress_algorithm) {
-               ctxt_size = round_up(ctxt_size, 8);
-               ksmbd_debug(SMB,
-                           "assemble SMB2_COMPRESSION_CAPABILITIES context\n");
-               /* Temporarily set to SMB3_COMPRESS_NONE */
-               build_compression_ctxt((struct smb2_compression_capabilities_context *)
-                                      (pneg_ctxt + ctxt_size),
-                                      conn->compress_algorithm);
-               neg_ctxt_cnt++;
-               ctxt_size += sizeof(struct smb2_compression_capabilities_context) + 2;
-       }
+       /* compression context not yet supported */
+       WARN_ON(conn->compress_algorithm != SMB3_COMPRESS_NONE);
 
        if (conn->posix_ext_supported) {
                ctxt_size = round_up(ctxt_size, 8);