From ddd0451fc8dbf94446c81500ff0dcee06c4057cb Mon Sep 17 00:00:00 2001 From: John Hughes Date: Sun, 4 Apr 2010 06:48:10 +0000 Subject: [PATCH] x.25 attempts to negotiate invalid throughput 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. 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. Signed-off-by: John Hughes Tested-by: Andrew Hendry Signed-off-by: David S. Miller --- net/x25/af_x25.c | 20 ++++++++++++++++---- net/x25/x25_facilities.c | 15 ++++++++++++--- 2 files changed, 28 insertions(+), 7 deletions(-) diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index fe26c01ef3e6..8ed51c926c50 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -588,7 +588,8 @@ 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; @@ -1459,9 +1460,20 @@ 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; diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c index a2765c6b1f1a..771bab00754b 100644 --- a/net/x25/x25_facilities.c +++ b/net/x25/x25_facilities.c @@ -269,9 +269,18 @@ 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; } } -- 2.20.1