4 files changed, 61 insertions, 7 deletions

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 5ff0b3d4c484..6a69f11aacf7 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -332,6 +332,12 @@ skip_rdma:
 #endif
                 seq_printf(m, "\nNumber of credits: %d Dialect 0x%x",
                         server->credits,  server->dialect);
+                if (server->compress_algorithm == SMB3_COMPRESS_LZNT1)
+                        seq_printf(m, " COMPRESS_LZNT1");
+                else if (server->compress_algorithm == SMB3_COMPRESS_LZ77)
+                        seq_printf(m, " COMPRESS_LZ77");
+                else if (server->compress_algorithm == SMB3_COMPRESS_LZ77_HUFF)
+                        seq_printf(m, " COMPRESS_LZ77_HUFF");
                 if (server->sign)
                         seq_printf(m, " signed");
                 if (server->posix_ext_supported)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index c22ab330238c..561f1395eddd 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -734,6 +734,7 @@ struct TCP_Server_Info {
 #endif /* STATS2 */
         unsigned int    max_read;
         unsigned int    max_write;
+        __le16  compress_algorithm;
         __le16  cipher_type;
          /* save initital negprot hash */
         __u8    preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 035a568b3dbd..29f011d8d8e2 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -473,6 +473,19 @@ build_preauth_ctxt(struct smb2_preauth_neg_context *pneg_ctxt)
 }
 
 static void
+build_compression_ctxt(struct smb2_compression_capabilities_context *pneg_ctxt)
+{
+        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->CompressionAlgorithmCount = cpu_to_le16(3);
+        pneg_ctxt->CompressionAlgorithms[0] = SMB3_COMPRESS_LZ77;
+        pneg_ctxt->CompressionAlgorithms[1] = SMB3_COMPRESS_LZ77_HUFF;
+        pneg_ctxt->CompressionAlgorithms[2] = SMB3_COMPRESS_LZNT1;
+}
+
+static void
 build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
 {
         pneg_ctxt->ContextType = SMB2_ENCRYPTION_CAPABILITIES;
@@ -538,10 +551,17 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
         *total_len += ctxt_len;
         pneg_ctxt += ctxt_len;
 
+        build_compression_ctxt((struct smb2_compression_capabilities_context *)
+                                pneg_ctxt);
+        ctxt_len = DIV_ROUND_UP(
+                sizeof(struct smb2_compression_capabilities_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);
 
-        req->NegotiateContextCount = cpu_to_le16(3);
+        req->NegotiateContextCount = cpu_to_le16(4);
 }
 
 static void decode_preauth_context(struct smb2_preauth_neg_context *ctxt)
@@ -559,6 +579,27 @@ static void decode_preauth_context(struct smb2_preauth_neg_context *ctxt)
                 printk_once(KERN_WARNING "unknown SMB3 hash algorithm\n");
 }
 
+static void decode_compress_ctx(struct TCP_Server_Info *server,
+                         struct smb2_compression_capabilities_context *ctxt)
+{
+        unsigned int len = le16_to_cpu(ctxt->DataLength);
+
+        /* sizeof compress context is a one element compression capbility struct */
+        if (len < 10) {
+                printk_once(KERN_WARNING "server sent bad compression cntxt\n");
+                return;
+        }
+        if (le16_to_cpu(ctxt->CompressionAlgorithmCount) != 1) {
+                printk_once(KERN_WARNING "illegal SMB3 compress algorithm count\n");
+                return;
+        }
+        if (le16_to_cpu(ctxt->CompressionAlgorithms[0]) > 3) {
+                printk_once(KERN_WARNING "unknown compression algorithm\n");
+                return;
+        }
+        server->compress_algorithm = ctxt->CompressionAlgorithms[0];
+}
+
 static int decode_encrypt_ctx(struct TCP_Server_Info *server,
                               struct smb2_encryption_neg_context *ctxt)
 {
@@ -623,6 +664,9 @@ 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_COMPRESSION_CAPABILITIES)
+                        decode_compress_ctx(server,
+                                (struct smb2_compression_capabilities_context *)pctx);
                 else if (pctx->ContextType == SMB2_POSIX_EXTENSIONS_AVAILABLE)
                         server->posix_ext_supported = true;
                 else
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 93dd3b431585..c7d5813bebd8 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -297,16 +297,19 @@ struct smb2_encryption_neg_context {
 } __packed;
 
 /* See MS-SMB2 2.2.3.1.3 */
-#define SMB3_COMPRESS_NONE      0x0000
-#define SMB3_COMPRESS_LZNT1     0x0001
-#define SMB3_COMPRESS_LZ77      0x0002
-#define SMB3_COMPRESS_LZ77_HUFF 0x0003
+#define SMB3_COMPRESS_NONE      cpu_to_le16(0x0000)
+#define SMB3_COMPRESS_LZNT1     cpu_to_le16(0x0001)
+#define SMB3_COMPRESS_LZ77      cpu_to_le16(0x0002)
+#define SMB3_COMPRESS_LZ77_HUFF cpu_to_le16(0x0003)
 
 struct smb2_compression_capabilities_context {
+        __le16  ContextType; /* 3 */
+        __le16  DataLength;
+        __u32   Reserved;
         __le16  CompressionAlgorithmCount;
         __u16   Padding;
-        __u32   Reserved;
-        __u16   CompressionAlgorithms[1];
+        __u32   Reserved1;
+        __le16  CompressionAlgorithms[3];
 } __packed;
 
 /*