From 7f87c6faf547071e0e503f4311349025411e3fdf Mon Sep 17 00:00:00 2001
From: Steve French <smfrench@gmail.com>
Date: Fri, 26 Apr 2019 20:36:08 -0700
Subject: [PATCH] [smb3] Negotiate and save preferred compression algorithms
New negotiate context (3) allows the server and client to
negotiate which compression algorithms to use. Add support
for this and save it off in the server structure.
Also now displayed in /proc/fs/cifs/DebugData (see below example
to Windows 10) where compression algoirthm "LZ77" was negotiated:
Servers:
Number of credits: 326 Dialect 0x311 COMPRESS_LZ77 signed
1) Name: 192.168.92.17 Uses: 1 Capability: 0x300067 Session Status: 1 TCP status: 1 Instance: 1
See MS-XCA and MS-SMB2 2.2.3.1 for more details.
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/cifs/cifs_debug.c | 6 ++++++
fs/cifs/cifsglob.h | 1 +
fs/cifs/smb2pdu.c | 47 +++++++++++++++++++++++++++++++++++++++++++-
fs/cifs/smb2pdu.h | 7 +++++--
4 files changed, 58 insertions(+), 3 deletions(-)
@@ -332,6 +332,12 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
#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)
@@ -734,6 +734,7 @@ struct TCP_Server_Info {
#endif /* STATS2 */
unsigned int max_read;
unsigned int max_write;
+ __u16 compress_algorithm;
__le16 cipher_type;
/* save initital negprot hash */
__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
@@ -472,6 +472,19 @@ build_preauth_ctxt(struct smb2_preauth_neg_context *pneg_ctxt)
pneg_ctxt->HashAlgorithms = SMB2_PREAUTH_INTEGRITY_SHA512;
}
+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)
{
@@ -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 +579,28 @@ 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 =
+ le16_to_cpu(ctxt->CompressionAlgorithms[0]);
+}
+
static int decode_encrypt_ctx(struct TCP_Server_Info *server,
struct smb2_encryption_neg_context *ctxt)
{
@@ -623,6 +665,9 @@ 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
@@ -303,10 +303,13 @@ struct smb2_encryption_neg_context {
#define SMB3_COMPRESS_LZ77_HUFF 0x0003
struct smb2_compression_capabilities_context {
+ __le16 ContextType; /* 3 */
+ __le16 DataLength;
+ __u32 Reserved;
__le16 CompressionAlgorithmCount;
__u16 Padding;
- __u32 Reserved;
- __u16 CompressionAlgorithms[1];
+ __u32 Reserved1;
+ __u16 CompressionAlgorithms[3];
} __packed;
/*
--
2.17.1