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Cause: pluto IKE daemon did not have the CAP_DAC_READ_SEARCH capability
Consequence: pam based authentication using pam_sss would fail.
Fix: pluto gained the CAP_DAC_READ_SEARCH capability
Result: authentication with pam_sss works
Created attachment 1092825[details]
upstream patch
Description of problem:
pluto's current effective|permitted capabilities don't allow a connection to the private pam socket, which is required when using the PAM xauth method and pam_sss.so is in the PAM stack. The auth requests never make it to the sssd pam responder - the stat against the socket in pam_sss' sss_pam_make_request() function fails with EACCES
12:10:04.617248 stat("/var/lib/sss/pipes/private/pam", 0x7fbbbeae7630) = -1 EACCES (Permission denied)
The attached patch adds CAP_DAC_READ_SEARCH to the effective|permitted set and will permit access to the private socket.
Version-Release number of selected component (if applicable):
libreswan-3.15-5.el7_1
How reproducible:
On an IPA client server with pam_sss enabled, configure libreswan as an XAUTH server using xauthby=pam, ie. https://libreswan.org/wiki/VPN_server_for_remote_clients_using_IKEv1_XAUTH
Test a remote client connection, entering an IPA provided user/password. Pluto will report an Authentication failure with no "pam_sss(pluto:auth)" entry in /var/log/secure, nor will there be any sssd logging that indicates a PAM client connection was received. The stat() error can be seen when attaching strace to pluto.
Successfully verified that xauth=pam works fine with pam_sss (on x86_64).
Old (libreswan-3.12-10.1.el7_1)
===============================
From pluto log:
XAUTH: Sending Username/Password request (XAUTH_R0)
XAUTH: User Amy.qe: Attempting to login
XAUTH: pam authentication being called to authenticate user Amy.qe
XAUTH: pam_authenticate failed with 'Authentication failure'
XAUTH: User Amy.qe: Authentication Failed: Incorrect Username or Password
No pam_sss(pluto:auth) in /var/log/secure.
New (libreswan-3.15-6.el7)
==========================
From pluto log:
XAUTH: Sending Username/Password request (XAUTH_R0)
XAUTH: User Amy.qe: Attempting to login
XAUTH: pam authentication being called to authenticate user Amy.qe
XAUTH: User Amy.qe: Authentication Successful
From /var/log/secure:
pluto: pam_sss(pluto:auth): authentication success; logname= uid=0 euid=0 tty= ruser= rhost=10.34.88.62 user=Amy.qe
For QE and future test automation, I am using the following:
* VPN server/client XAUTH with PSK from [1]
* SSSD & AD from /CoreOS/realmd/Sanity/AD-join-leave-sanity-test
[1] https://libreswan.org/wiki/VPN_server_for_remote_clients_using_IKEv1_XAUTH_with_PSK
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHSA-2016-2603.html