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SMB3 permits a message to be compressed before it is encrypted. After
decrypting such a request, ksmbd must trim the AEAD tag using
OriginalMessageSize, decompress the nested compression transform, and
validate the resulting SMB2 PDU.
Share the decompression helper between the connection receive path and
the post-decryption work path so unencrypted and encrypted compressed
requests follow the same validation.
Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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ksmbd_conn_handler_loop() caps a request from an unauthenticated
connection at SMB3_MAX_MSGSIZE, and only allows the larger
SMB3_MAX_MSGSIZE + conn->vals->max_write_size once the connection has
authenticated.
ksmbd_decompress_request() runs inside that same loop but applies the
authenticated limit unconditionally, and then allocates from it. The
unauthenticated cap is not re-applied afterwards, as the caller only
refreshes pdu_size from the new RFC1002 header.
An unauthenticated client that negotiates SMB 3.1.1 with a compression
context can therefore send a 104 byte chained transform whose
OriginalCompressedSegmentSize is SMB3_MAX_MSGSIZE + max_write_size and
have ksmbd kvmalloc() that much memory, 4210693 bytes by default. The
payload costs the client nothing, because a SMB3_COMPRESS_PATTERN
payload expands an eight byte structure into arbitrarily many output
bytes.
The decompressed PDU is rejected later by ksmbd_smb2_check_message(),
but that happens in the worker, after the allocation has been made and
conn->req_running has been incremented, and it results in an error
response rather than dropping the connection. A client that stops
reading its socket keeps each work queued for up to KSMBD_TCP_SEND_TIMEOUT
while ksmbd_conn_write() holds conn->srv_mutex, so the allocations
accumulate up to server_conf.max_inflight_req per connection.
Move the limit into ksmbd_max_allowed_pdu_size() and call it from both
sites, so the authentication state is consulted in one place and the two
ceilings cannot drift apart again.
Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression")
Signed-off-by: Sujal Tuladhar <sujaltuladhar1231@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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ksmbd_decompress_request() allocated the decompressed request buffer
before smb_compression_decompress() rejected unknown transform Flags or
chained mode when it was not negotiated. A remote peer could force a
transient multi-megabyte allocation that was immediately freed on
-EINVAL.
Validate CHAINED/NONE Flags and compress_chained before kvmalloc.
Link: https://github.com/namjaejeon/ksmbd/issues/529
Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression")
Signed-off-by: Anatolii Shumak <anatoliy.shumak@gmail.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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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
Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression")
Signed-off-by: Anatolii Shumak <anatoliy.shumak@gmail.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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ksmbd_decompress_request() bounds the decompressed size only against
the maximum request size. A compression transform can therefore
produce a buffer smaller than an SMB2 PDU and install it as
conn->request_buf.
The receive path subsequently calls ksmbd_smb_request(), which reads
the protocol ID before the normal SMB2 minimum-size check. If the
decompressed output is too short, that read can access beyond the
request allocation.
Require the decompressed output to contain at least a complete minimum
SMB2 PDU before allocating and installing the replacement request
buffer.
Fixes: a08de24c2b85 ("ksmbd: negotiate and decode SMB2 compression")
Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Handle SMB2_READFLAG_REQUEST_COMPRESSED for non-RDMA reads.
Flatten the response iov, emit chained or unchained LZ77 transforms when
compression is beneficial, and retain the generated buffer until the work
item is released.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Parse the SMB 3.1.1 compression capabilities context and negotiate LZ77
with optional chained Pattern_V1 support.
Advertise compression on tree connections and decode compressed requests
before normal SMB dispatch.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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