[PATCH RFC v2 0/3] smb: fix minimum PDU size

[PATCH RFC v2 0/3] smb: fix minimum PDU size

[chenxiaosong.chenxiaosong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

If my understanding is incorrect, please let me know.

v1: https://lore.kernel.org/all/20251218171038.55266-1-chenxiaosong.chenxiaosong@linux.dev/
v1->v2:
  - Create patch #0001 #0003
  - Patch #0002: update value of SMB2_MIN_SUPPORTED_PDU_SIZE

ChenXiaoSong (3):
  smb/server: fix minimum SMB1 PDU size
  smb/server: fix minimum SMB2 PDU size
  smb: use sizeof() to get __SMB2_HEADER_STRUCTURE_SIZE

 fs/smb/common/smb1pdu.h    | 5 +++++
 fs/smb/common/smb2pdu.h    | 8 ++++----
 fs/smb/server/connection.c | 8 ++++----
 3 files changed, 13 insertions(+), 8 deletions(-)

-- 
2.43.0

[PATCH RFC v2 1/3] smb/server: fix minimum SMB1 PDU size

[chenxiaosong.chenxiaosong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

Since the RFC1002 header has been removed from `struct smb_hdr`,
the minimum SMB1 PDU size should be updated as well.

Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr")
Suggested-by: David Howells <dhowells@redhat.com>
Suggested-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/common/smb1pdu.h    | 5 +++++
 fs/smb/server/connection.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/smb/common/smb1pdu.h b/fs/smb/common/smb1pdu.h
index df6d4e11ae92..3c5332a82ea7 100644
--- a/fs/smb/common/smb1pdu.h
+++ b/fs/smb/common/smb1pdu.h
@@ -53,4 +53,9 @@ typedef struct smb_negotiate_req {
 	unsigned char DialectsArray[];
 } __packed SMB_NEGOTIATE_REQ;
 
+struct smb_pdu {
+	struct smb_hdr;
+	__le16 ByteCount;
+} __packed;
+
 #endif /* _COMMON_SMB1_PDU_H */
diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c
index b6b4f1286b9c..f372486ebcc5 100644
--- a/fs/smb/server/connection.c
+++ b/fs/smb/server/connection.c
@@ -295,7 +295,7 @@ bool ksmbd_conn_alive(struct ksmbd_conn *conn)
 	return true;
 }
 
-#define SMB1_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb_hdr))
+#define SMB1_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb_pdu))
 #define SMB2_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb2_hdr) + 4)
 
 /**
@@ -363,7 +363,7 @@ int ksmbd_conn_handler_loop(void *p)
 		if (pdu_size > MAX_STREAM_PROT_LEN)
 			break;
 
-		if (pdu_size < SMB1_MIN_SUPPORTED_HEADER_SIZE)
+		if (pdu_size < SMB1_MIN_SUPPORTED_PDU_SIZE)
 			break;
 
 		/* 4 for rfc1002 length field */
-- 
2.43.0

[PATCH RFC v2 2/3] smb/server: fix minimum SMB2 PDU size

[chenxiaosong.chenxiaosong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

The minimum SMB2 PDU size should be updated to the size of
`struct smb_pdu`.

Suggested-by: David Howells <dhowells@redhat.com>
Suggested-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/server/connection.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c
index f372486ebcc5..4a8eb4fef763 100644
--- a/fs/smb/server/connection.c
+++ b/fs/smb/server/connection.c
@@ -296,7 +296,7 @@ bool ksmbd_conn_alive(struct ksmbd_conn *conn)
 }
 
 #define SMB1_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb_pdu))
-#define SMB2_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb2_hdr) + 4)
+#define SMB2_MIN_SUPPORTED_PDU_SIZE (sizeof(struct smb2_pdu))
 
 /**
  * ksmbd_conn_handler_loop() - session thread to listen on new smb requests
@@ -396,7 +396,7 @@ int ksmbd_conn_handler_loop(void *p)
 
 		if (((struct smb2_hdr *)smb2_get_msg(conn->request_buf))->ProtocolId ==
 		    SMB2_PROTO_NUMBER) {
-			if (pdu_size < SMB2_MIN_SUPPORTED_HEADER_SIZE)
+			if (pdu_size < SMB2_MIN_SUPPORTED_PDU_SIZE)
 				break;
 		}
 
-- 
2.43.0

[PATCH RFC v2 3/3] smb: use sizeof() to get __SMB2_HEADER_STRUCTURE_SIZE

[chenxiaosong.chenxiaosong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

I have checked the size of the structure using GDB:

  gdb ./build/fs/smb/server/ksmbd.ko
  (gdb) p sizeof(struct smb2_hdr)
  $1 = 64

  gdb ./build/fs/smb/client/cifs.ko
  (gdb) p sizeof(struct smb2_hdr)
  $1 = 64

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/common/smb2pdu.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/smb/common/smb2pdu.h b/fs/smb/common/smb2pdu.h
index f5ebbe31384a..f2a6b7191f43 100644
--- a/fs/smb/common/smb2pdu.h
+++ b/fs/smb/common/smb2pdu.h
@@ -107,10 +107,6 @@
  *
  */
 
-#define __SMB2_HEADER_STRUCTURE_SIZE	64
-#define SMB2_HEADER_STRUCTURE_SIZE				\
-	cpu_to_le16(__SMB2_HEADER_STRUCTURE_SIZE)
-
 #define SMB2_PROTO_NUMBER cpu_to_le32(0x424d53fe)
 #define SMB2_TRANSFORM_PROTO_NUM cpu_to_le32(0x424d53fd)
 #define SMB2_COMPRESSION_TRANSFORM_ID cpu_to_le32(0x424d53fc)
@@ -157,6 +153,10 @@ struct smb2_hdr {
 	__u8   Signature[16];
 } __packed;
 
+#define __SMB2_HEADER_STRUCTURE_SIZE	(sizeof(struct smb2_hdr))
+#define SMB2_HEADER_STRUCTURE_SIZE				\
+	cpu_to_le16(__SMB2_HEADER_STRUCTURE_SIZE)
+
 struct smb3_hdr_req {
 	__le32 ProtocolId;	/* 0xFE 'S' 'M' 'B' */
 	__le16 StructureSize;	/* 64 */
-- 
2.43.0