RE: [PATCH 3.16 155/178] cifs: Do not send echoes before Negotiate is complete

[Pavel Shilovskiy]

2017-07-16 6:57 Ben Hutchings :
> 
> 3.16.46-rc1 review patch.  If anyone has any objections, please let me know.
> 
> --
> 
> From: Sachin Prabhu 
> 
> commit 62a6cfddcc0a5313e7da3e8311ba16226fe0ac10 upstream.
> 
> commit 4fcd1813e640 ("Fix reconnect to not defer smb3 session reconnect long 
> after socket reconnect") added support for Negotiate requests to be initiated 
> by echo calls.
> 
> To avoid delays in calling echo after a reconnect, I added the patch 
> introduced by the commit b8c600120fc8 ("Call echo service immediately after 
> socket reconnect").
>
> This has however caused a regression with cifs shares which do not have 
> support for echo calls to trigger Negotiate requests. On connections which 
> need to call Negotiation, the echo calls trigger an error which triggers a 
> reconnect which in turn triggers another echo call. This results in a loop 
> which is only broken when an operation is performed on the cifs share. For an 
> idle share, it can DOS a server.
> 
> The patch uses the smb_operation can_echo() for cifs so that it is called 
> only if connection has been already been setup.
> 
> kernel bz: 194531
> 
> Signed-off-by: Sachin Prabhu 
> Tested-by: Jonathan Liu 
> Acked-by: Pavel Shilovsky 
> Signed-off-by: Steve French 
> Signed-off-by: Ben Hutchings 
> ---
> fs/cifs/smb1ops.c | 10 ++
> 1 file changed, 10 insertions(+)

I have just posted a backport of commit b8c600120fc8 ("Call echo service 
immediately after socket reconnect") for v3.16.x kernel to the stable mailing 
list. Please consider merging it too.

Best regards,
Pavel Shilovsky

RE: [PATCH 3.16 155/178] cifs: Do not send echoes before Negotiate is complete

[Pavel Shilovskiy]

2017-07-16 6:57 Ben Hutchings :
> 
> 3.16.46-rc1 review patch.  If anyone has any objections, please let me know.
> 
> --
> 
> From: Sachin Prabhu 
> 
> commit 62a6cfddcc0a5313e7da3e8311ba16226fe0ac10 upstream.
> 
> commit 4fcd1813e640 ("Fix reconnect to not defer smb3 session reconnect long 
> after socket reconnect") added support for Negotiate requests to be initiated 
> by echo calls.
> 
> To avoid delays in calling echo after a reconnect, I added the patch 
> introduced by the commit b8c600120fc8 ("Call echo service immediately after 
> socket reconnect").
>
> This has however caused a regression with cifs shares which do not have 
> support for echo calls to trigger Negotiate requests. On connections which 
> need to call Negotiation, the echo calls trigger an error which triggers a 
> reconnect which in turn triggers another echo call. This results in a loop 
> which is only broken when an operation is performed on the cifs share. For an 
> idle share, it can DOS a server.
> 
> The patch uses the smb_operation can_echo() for cifs so that it is called 
> only if connection has been already been setup.
> 
> kernel bz: 194531
> 
> Signed-off-by: Sachin Prabhu 
> Tested-by: Jonathan Liu 
> Acked-by: Pavel Shilovsky 
> Signed-off-by: Steve French 
> Signed-off-by: Ben Hutchings 
> ---
> fs/cifs/smb1ops.c | 10 ++
> 1 file changed, 10 insertions(+)

I have just posted a backport of commit b8c600120fc8 ("Call echo service 
immediately after socket reconnect") for v3.16.x kernel to the stable mailing 
list. Please consider merging it too.

Best regards,
Pavel Shilovsky