Package: xinetd
Version: 1:2.3.13-3
Severity: important
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From: Philipp Grau <[EMAIL PROTECTED]>
To: Debian Bug Tracking System <[EMAIL PROTECTED]>
Subject: xinetd: tcpmux does not change the uid of server proccess
X-Reportbug-Version: 3.8
Package: xinetd
Version: 1:2.3.13-3
Severity: important
Using the TCPMUXPLUS internal service of xinetd does not work as
expected. xinetd does not change the uid of a server proccess if the
service is called via TCPMUX(PLUS). The configuration attribute "user"
does not take any effect.
Example to reproduce the error:
Using the following configuration:
----------8<--------snipp---------8<-------------------------
# cut'n'paste from xinetd.conf(5)
service tcpmux
{
disable = no
type = INTERNAL
id = tcpmux
socket_type = stream
protocol = tcp
user = root
wait = no
}
# test example
service test_server
{
disable = no
type = TCPMUXPLUS
socket_type = stream
protocol = tcp
wait = no
user = testuser
server = /usr/bin/id
}
----------8<--------snipp---------8<-------------------------
Using the above configuration we get the following result:
$ telnet 127.0.0. 1
Trying 127.0.0.1...
test_server
+Go
uid=0(root) gid=0(root) groups=0(root)
Connection closed by foreign host.
The expected result would have been:
$ telnet 127.0.0. 1
Trying 127.0.0.1...
test_server
+Go
uid=1000(testuser) gid=1000(testuser) groups=1000(testuser)
Connection closed by foreign host.
Futher hints:
After looking through the sources, it seems like there is something
missing in the TCPMUX implementation. The sub-service is called by
exec_server() and then an execve() is called to start the external
program. No setuid() before the execve().
A setuid() call is only made for child_process() in set_credentials().
So it is possible to run TCPMUX under a different uid, but not the
sub-service.
-- System Information:
Debian Release: 3.1
Architecture: i386 (i686)
Kernel: Linux 2.6.11.10.20050519
Locale: LANG=C, LC_CTYPE=de_DE.ISO8859-1 (charmap=ISO-8859-1)
Versions of packages xinetd depends on:
ii libc6 2.3.2.ds1-22 GNU C Library: Shared libraries an
ii libwrap0 7.6.dbs-8 Wietse Venema's TCP wrappers libra
hi netbase 4.19 Basic TCP/IP networking system
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