[PATCH 1/2] smb: compress: reject Pattern_V1 when not negotiated

Pattern_V1 is an optional chained payload type selected during SMB 3.1.1
compression negotiate. conn->compress_pattern was only consulted when
building responses, so a peer that negotiated LZ77 with chained support
could still submit Pattern payloads on the receive path.

Pass allow_pattern through smb_compression_decompress() and reject
SMB3_COMPRESS_PATTERN in the chained decoder when it is false.

Link: https://github.com/namjaejeon/ksmbd/issues/529
Signed-off-by: Anatolii Shumak <[email protected]>
---
 fs/smb/common/compress/compress.c | 11 ++++++++---
 fs/smb/common/compress/compress.h |  3 ++-
 fs/smb/server/compress.c          |  1 +
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/smb/common/compress/compress.c b/fs/smb/common/compress/compress.c
index b07a317597a4..a4123c8f1c0a 100644
--- a/fs/smb/common/compress/compress.c
+++ b/fs/smb/common/compress/compress.c
@@ -95,6 +95,7 @@ static int smb_decompress_lz77_payload(const u8 **src, u32 *slen, u8 **dst,
 }
 
 static int smb_decompress_chained(__le16 alg, bool allow_chained,
+				  bool allow_pattern,
 				  const struct smb2_compression_hdr *hdr,
 				  u32 slen, void *dst, u32 dlen)
 {
@@ -143,6 +144,8 @@ static int smb_decompress_chained(__le16 alg, bool allow_chained,
 			rc = smb_decompress_none(&src, &remaining, &out,
 						 &out_remaining, len);
 		} else if (payload_alg == SMB3_COMPRESS_PATTERN) {
+			if (!allow_pattern)
+				return -EINVAL;
 			rc = smb_decompress_pattern(&src, &remaining, &out,
 						    &out_remaining, len);
 		} else if (payload_alg == alg && alg == SMB3_COMPRESS_LZ77) {
@@ -185,6 +188,7 @@ static int smb_decompress_unchained(__le16 alg,
  * smb_compression_decompress() - decode an SMB2 compression transform
  * @alg: negotiated general-purpose compression algorithm
  * @allow_chained: whether chained transforms were negotiated
+ * @allow_pattern: whether Pattern_V1 payloads were negotiated
  * @src: transform header followed by compressed payload data
  * @slen: total number of bytes available at @src
  * @dst: output buffer for the reconstructed SMB2 message
@@ -197,7 +201,8 @@ static int smb_decompress_unchained(__le16 alg,
  * Return: 0 on success, otherwise a negative errno.
  */
 int smb_compression_decompress(__le16 alg, bool allow_chained,
-			       const void *src, u32 slen, void *dst, u32 dlen)
+			       bool allow_pattern, const void *src, u32 slen,
+			       void *dst, u32 dlen)
 {
 	const struct smb2_compression_hdr *hdr = src;
 
@@ -207,8 +212,8 @@ int smb_compression_decompress(__le16 alg, bool allow_chained,
 		return -EINVAL;
 
 	if (hdr->Flags == cpu_to_le16(SMB2_COMPRESSION_FLAG_CHAINED))
-		return smb_decompress_chained(alg, allow_chained, hdr, slen,
-					      dst, dlen);
+		return smb_decompress_chained(alg, allow_chained, allow_pattern,
+					      hdr, slen, dst, dlen);
 
 	if (hdr->Flags != cpu_to_le16(SMB2_COMPRESSION_FLAG_NONE))
 		return -EINVAL;
diff --git a/fs/smb/common/compress/compress.h b/fs/smb/common/compress/compress.h
index 7ace3bf4b664..d6916669f887 100644
--- a/fs/smb/common/compress/compress.h
+++ b/fs/smb/common/compress/compress.h
@@ -20,7 +20,8 @@ static __always_inline bool smb_compress_alg_valid(__le16 alg, bool valid_none)
 }
 
 int smb_compression_decompress(__le16 alg, bool allow_chained,
-			       const void *src, u32 slen, void *dst, u32 dlen);
+			       bool allow_pattern, const void *src, u32 slen,
+			       void *dst, u32 dlen);
 int smb_compression_compress_chained(__le16 alg, bool allow_pattern,
 				     const void *src, u32 slen,
 				     void *dst, u32 *dlen);
diff --git a/fs/smb/server/compress.c b/fs/smb/server/compress.c
index 95e48fa6b448..821299888ad3 100644
--- a/fs/smb/server/compress.c
+++ b/fs/smb/server/compress.c
@@ -69,6 +69,7 @@ int ksmbd_decompress_request(struct ksmbd_conn *conn)
 	*(__be32 *)out = cpu_to_be32(out_size);
 	rc = smb_compression_decompress(conn->compress_algorithm,
 					conn->compress_chained,
+					conn->compress_pattern,
 					buf, pdu_size, out + 4, out_size);
 	if (rc) {
 		kvfree(out);
-- 
2.51.0.windows.2