Re: [PATCH 2/3] ksmbd: fix partial normalized name responses

[ChenXiaoSong <chenxiaosong@chenxiaosong.com>]

Hi Namjae,

According to MS-FSA 2.1.5.12.30: 
https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fsa/3d5c68f8-fbc5-4f94-a51d-3600a319fd45

   Set AvailableNameLength to BlockAlignTruncate((OutputBufferSize - 
FieldOffset(FILE_NAME_INFORMATION.FileName)), 2).

It seems that the following changes are also needed:
```
smb2_get_info_file()
{
         unsigned int req_output_len = le32_to_cpu(req->OutputBufferLength);
...
         case FILE_NORMALIZED_NAME_INFORMATION:
                 fixed_len = FILE_NORMALIZED_NAME_INFORMATION_SIZE;
                 req_output_len = round_down(req_output_len, 2);
                 break;
...
         rc = buffer_check_err(req_output_len, fixed_len, rsp);
}
```

By the way, it seems that `struct smb2_file_alt_name_info` should be 
renamed to `struct smb2_file_name_info`, since both 
FILE_ALTERNATE_NAME_INFORMATION and FILE_NORMALIZED_NAME_INFORMATION use 
this structure. See:
- MS-FSA 2.1.5.12.4 FileAlternateNameInformation: 
https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fsa/5051d021-8d06-4b7e-94e3-55b118193427
- MS-FSA 2.1.5.12.30 FileNormalizedNameInformation: 
https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fsa/3d5c68f8-fbc5-4f94-a51d-3600a319fd45

On 9/13/26 19:35, Namjae Jeon wrote:
> Windows may request FILE_NORMALIZED_NAME_INFORMATION with an output
> buffer that only fits the fixed portion of the variable-length response.
> Treat the fixed portion as FILE_ALTERNATE_NAME_INFORMATION_SIZE so ksmbd
> returns STATUS_BUFFER_OVERFLOW instead of STATUS_INFO_LENGTH_MISMATCH.
> 
> This avoids rejecting valid partial normalized-name responses.
> 
> Fixes: 6b8b79226bc3 ("ksmbd: fix partial file information responses")
> Reported-by: Mobin Aydinfar <mobin@mobintestserver.ir>
> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
> ---
>   fs/smb/server/smb2pdu.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
> index f4d96799e1d2..38cddbf3e6ed 100644
> --- a/fs/smb/server/smb2pdu.c
> +++ b/fs/smb/server/smb2pdu.c
> @@ -7318,6 +7318,9 @@ static int smb2_get_info_file(struct ksmbd_work *work,
>   		case FILE_ALTERNATE_NAME_INFORMATION:
>   			fixed_len = FILE_ALTERNATE_NAME_INFORMATION_SIZE;
>   			break;
> +		case FILE_NORMALIZED_NAME_INFORMATION:
> +			fixed_len = FILE_ALTERNATE_NAME_INFORMATION_SIZE;
> +			break;
>   		case FILE_STREAM_INFORMATION:
>   			fixed_len = FILE_STREAM_INFORMATION_SIZE;
>   			break;

-- 
ChenXiaoSong <chenxiaosong@chenxiaosong.com>
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