patch to improve x.25 throughput negotiation
Subsystems (3)
The current X.25 code has some bugs in throughput negotiation:
1. It does negotiation in all cases, usually there is no need
2. It incorrectly attempts to negotiate the throughput class in one direction only. There are separate throughput classes for input and output and if either is negotiated both mist be negotiates.
This is bug https://bugzilla.kernel.org/show_bug.cgi?id=15681
This bug was first reported by Daniel Ferenci to the linux-x25 mailing list on 6/8/2004, but is still present.
From: John Hughes <[email protected]>
Subject: x.25 attempts to negotiate invalid throughput
The current (2.6.34) x.25 code doesn't seem to know that the X.25 throughput facility includes two values, one for the required throughput outbound, one for inbound.
This causes it to attempt to negotiate throughput 0x0A, which is throughput 9600 inbound and the illegal value "0" for inbound throughput.
Because of this some X.25 devices (e.g. Cisco 1600) refuse to connect to Linux X.25.
The following patch fixes this behaviour. Unless the user specifies a required throughput it does not attempt to negotiate. If the user does not specify a throughput it accepts the suggestion of the remote X.25 system. If the user requests a throughput then it validates both the input and output throughputs and correctly negotiates them with the remote end.
net/x25/af_x25.c +16 -4
@@ -553,7 +553,8 @@ static int x25_create(struct net *net, struct socket *sock, int protocol, x25->facilities.winsize_out =X25_DEFAULT_WINDOW_SIZE ; x25->facilities.pacsize_in =X25_DEFAULT_PACKET_SIZE ; x25->facilities.pacsize_out =X25_DEFAULT_PACKET_SIZE ; - x25->facilities.throughput =X25_DEFAULT_THROUGHPUT ; + x25->facilities.throughput =0 ;/* by default don't negotiate +throughput */ x25->facilities.reverse =X25_DEFAULT_REVERSE ; x25->dte_facilities.calling_len =0 ; x25->dte_facilities.called_len =0 ;
@@ -1414,9 +1415,20 @@ static int x25_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)if (facilities.winsize_in <1 || facilities.winsize_in >127 )break ; -if (facilities.throughput <0x03 || - facilities.throughput >0xDD ) -break ; +if (facilities.throughput) { +int out = facilities.throughput &0xf0 ; +int in = facilities.throughput &0x0f ; +if (!out) + facilities.throughput |= +X25_DEFAULT_THROUGHPUT <<4 ; +else if (out <0x30 || out >0xD0 ) +break ; +if (!in) + facilities.throughput |= +X25_DEFAULT_THROUGHPUT ; +else if (in <0x03 || in >0x0D ) +break ; + }if (facilities.reverse && (facilities.reverse &0x81 ) !=0x81 )break ;
net/x25/x25_facilities.c +12 -3
@@ -259,9 +259,18 @@ int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, new->reverse = theirs.reverse;if (theirs.throughput) { -if (theirs.throughput < ours->throughput) { -SOCK_DEBUG (sk,"X.25: throughput negotiated down\n" ); - new->throughput = theirs.throughput; +int theirs_in = theirs.throughput &0x0f ; +int theirs_out = theirs.throughput &0xf0 ; +int ours_in = ours->throughput &0x0f ; +int ours_out = ours->throughput &0xf0 ; +if (!ours_in || theirs_in < ours_in) { +SOCK_DEBUG (sk,"X.25: inbound throughput negotiated\n" ); + new->throughput = (new->throughput &0xf0 ) | theirs_in; + } +if (!ours_out || theirs_out < ours_out) { +SOCK_DEBUG (sk, +"X.25: outbound throughput negotiated\n" ); + new->throughput = (new->throughput &0x0f ) | theirs_out; } }
andrew hendry
Tested-byI have reproduced a few ways.
1. X25_MASK_THROUGHPUT on the x25_subscript_struct, then call SIOCX25SSUBSCRIP, then call SIOCX25FACILITIES without setting the throughput field. Call connect.
2. No subscrip setting, call SIOCX25FACILITIES without setting the throughput field. Call connect.
3. No subcrip, no facilities ioctl, call connect.
The patch removes the bad facility and makes the router accept the call for the above cases.
I don't currently have a setup to test both direction throughput negotiation.
Quoted 13 lines · John Hughes
The current X.25 code has some bugs in throughput negotiation:
1. It does negotiation in all cases, usually there is no need
2. It incorrectly attempts to negotiate the throughput class in one direction only. There are separate throughput classes for input and output and if either is negotiated both mist be negotiates.This is bug https://bugzilla.kernel.org/show_bug.cgi?id=15681
This bug was first reported by Daniel Ferenci to the linux-x25 mailing list on 6/8/2004, but is still present.
Quoted 8 lines · andrew hendry
I have reproduced a few ways.
1.X25_MASK_THROUGHPUTon thex25_subscript_struct, then call SIOCX25SSUBSCRIP, then call SIOCX25FACILITIES without setting the throughput field. Call connect.
2. No subscrip setting, call SIOCX25FACILITIES without setting the throughput field. Call connect.
3. No subcrip, no facilities ioctl, call connect.
Quoted 4 lines
The patch removes the bad facility and makes the router accept the call for the above cases.
I don't currently have a setup to test both direction throughput negotiation.
Summary: works for you (as far as you were able to test it).
Great news!
David Miller
maintainerFrom: andrew hendry <[email protected]>
Date: Tue, 6 Apr 2010 22:09:10 +1000
Quoted 8 lines
I have reproduced a few ways.
1.X25_MASK_THROUGHPUTon thex25_subscript_struct, then call SIOCX25SSUBSCRIP, then call SIOCX25FACILITIES without setting the throughput field. Call connect.
2. No subscrip setting, call SIOCX25FACILITIES without setting the throughput field. Call connect.
3. No subcrip, no facilities ioctl, call connect.
Quoted 5 lines
The patch removes the bad facility and makes the router accept the call for the above cases.
I don't currently have a setup to test both direction throughput negotiation.Tested-by Andrew Hendry <[email protected]>
Patch applied, thanks everyone.