Bug 205129 - TCP wrappers leave SIGALRM blocked when ident fails
Summary: TCP wrappers leave SIGALRM blocked when ident fails
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: tcp_wrappers
Version: 5
Hardware: All
OS: Linux
medium
low
Target Milestone: ---
Assignee: Tomas Janousek
QA Contact: David Lawrence
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2006-09-04 13:28 UTC by Jan "Yenya" Kasprzak
Modified: 2007-11-30 22:11 UTC (History)
0 users

Fixed In Version: tcp_wrappers-7.6-40.3.fc5
Clone Of:
Environment:
Last Closed: 2007-04-18 13:47:05 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description Jan "Yenya" Kasprzak 2006-09-04 13:28:15 UTC
Description of problem:
When tcp wrappers try to query a remote ident server, which is blocked (e.g. by
iptables), it leaves SIGALRM blocked. This is especially bad for sshd, because
then whole session then runs with SIGALRM blocked.

Version-Release number of selected component (if applicable):
tcp_wrappers-7.6-40.2
openssh-4.3p2-4

How reproducible:
100%


Steps to Reproduce:
1. on ssh client: "iptables -I INPUT -p tcp --dport ident -j DROP"
2. on ssh server: configure TCP wrappers to do an ident lookup (e.g. add "sshd:
ALL@ALL" line to /etc/hosts.allow)
3a. on ssh client: "ssh user@server 'ps xs|grep $$|grep -v grep'"
or 3b. on ssh client: "ssh user@server", and in the ssh session run something
like this:

perl -e '$SIG{ALRM}=sub{print"ALARM\n";}; alarm 1; sleep 5'

Actual results:
3a: the "BLOCKED" column of SSH output contains SIGALRM (BLOCKED & 0x2000
is 0x2000 on Linux/x86_64 and Linux/i386).
3b: no message is printed.


Expected results:
3a: BLOCKED & 0x2000 should be zero
3b: the "ALARM\n" message should be printed.


Additional info:
In the following message, Wietse Venema suggests that tcp_wrappers code is
correct and the bug is added by third parties:
http://www.gatago.com/mailing/unix/openssh-dev/4854382.html

Debian bug #354855 (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=354855)
apparently contains a patch for this problem. (META: this bugzilla does not have
 Debian bug tracking system available in "External Bug Reference" list).

Comment 1 Fedora Update System 2007-04-18 22:39:33 UTC
tcp_wrappers-7.6-40.3.fc6 has been pushed for fc6, which should resolve this issue.  If these problems are still present in this version, then please make note of it in this bug report.

Comment 2 Fedora Update System 2007-04-18 22:41:32 UTC
tcp_wrappers-7.6-40.3.fc5 has been pushed for fc5, which should resolve this issue.  If these problems are still present in this version, then please make note of it in this bug report.


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