6

I know that official CentOS 6 (even 7) update repositories does not provide security information. The consequence is thatyum-plugin-security plugin and yum check-update --security command does not list any updates like on RHEL or OEL distros.

There is a nice script generate_updateinfo which is able to inject missing piece of security information into local yum repository. The plugin will then work even on CentOS.

Unfortunately, I have a small issue with it. I'm not sure if the problem is with the script or with how yum is working.

How to reproduce the issue (tested on CentOS 6.8, x86_64, but IMO, previous/newer versions suffer from the same issue):

  1. first, let's clean everything to start with clean table
yum clean all
  1. let's see what security updates are available (the system is not up-to-date)
yum check-update --security
...
56 package(s) needed for security, out of 28 available

kernel.x86_64                                 2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-devel.x86_64                           2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-firmware.noarch                        2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-headers.x86_64                         2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
libtiff.x86_64                                3.9.4-21.el6_8                              local-centos-6-x86_64-updates
openssl.x86_64                                1.0.1e-48.el6_8.4                           local-centos-6-x86_64-updates
sudo.x86_64                                   1.8.6p3-25.el6_8                            local-centos-6-x86_64-updates
  1. now, let's install e.g. squid package
yum install -y squid 
...
Resolving Dependencies
--> Running transaction check
---> Package squid.x86_64 7:3.1.23-16.el6_8.6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================================
 Package           Arch               Version                          Repository                              Size
====================================================================================================================
Installing:
 squid             x86_64             7:3.1.23-16.el6_8.6              lp-centos-6-x86_64-updates             1.8 M

Transaction Summary
====================================================================================================================
Install       1 Package(s)

Total download size: 1.8 M
Installed size: 6.3 M
Downloading Packages:
squid-3.1.23-16.el6_8.6.x86_64.rpm                                                           | 1.8 MB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
  Installing : 7:squid-3.1.23-16.el6_8.6.x86_64                                                                 1/1
  Verifying  : 7:squid-3.1.23-16.el6_8.6.x86_64                                                                 1/1

Installed:
  squid.x86_64 7:3.1.23-16.el6_8.6

Complete!
  1. I would like to test update of the package so let's try to downgrade it first
yum downgrade -y squid
...
Resolving Dependencies
--> Running transaction check
---> Package squid.x86_64 7:3.1.23-16.el6_8.5 will be a downgrade
---> Package squid.x86_64 7:3.1.23-16.el6_8.6 will be erased
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================================
 Package           Arch               Version                          Repository                              Size
====================================================================================================================
Downgrading:
 squid             x86_64             7:3.1.23-16.el6_8.5              lp-centos-6-x86_64-updates             1.8 M

Transaction Summary
====================================================================================================================
Downgrade     1 Package(s)

Total download size: 1.8 M
Downloading Packages:
squid-3.1.23-16.el6_8.5.x86_64.rpm                                                           | 1.8 MB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : 7:squid-3.1.23-16.el6_8.5.x86_64                                                                 1/2
  Cleanup    : 7:squid-3.1.23-16.el6_8.6.x86_64                                                                 2/2
  Verifying  : 7:squid-3.1.23-16.el6_8.5.x86_64                                                                 1/2
  Verifying  : 7:squid-3.1.23-16.el6_8.6.x86_64                                                                 2/2

Removed:
  squid.x86_64 7:3.1.23-16.el6_8.6

Installed:
  squid.x86_64 7:3.1.23-16.el6_8.5

Complete!
  1. let's rather double-check what it is installed
rpm -qa | grep -i squid
squid-3.1.23-16.el6_8.5.x86_64
  1. at this moment, I would expect that when I check security updates again the squid package should be newly listed but it isn't
yum check-update --security
...
56 package(s) needed for security, out of 28 available

kernel.x86_64                                 2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-devel.x86_64                           2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-firmware.noarch                        2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
kernel-headers.x86_64                         2.6.32-642.15.1.el6                         local-centos-6-x86_64-updates
libtiff.x86_64                                3.9.4-21.el6_8                              local-centos-6-x86_64-updates
openssl.x86_64                                1.0.1e-48.el6_8.4                           local-centos-6-x86_64-updates
sudo.x86_64                                   1.8.6p3-25.el6_8                            local-centos-6-x86_64-updates
  1. let's see what squid errata are installed on the system. This is somehow weird. From the above, I can see the squid was downgraded to squid-3.1.23-16.el6_8.5.x86_64 (CEBA_2016__1412 bugfix) but squid-3.1.23-16.el6_8.6.x86_64 (CESA_2016__1573) seems to be still marked as installed
yum updateinfo list all | grep squid-3

i CESA_2011__1791 Moderate/Sec.  squid-3.1.10-1.el6_2.1.x86_64
i CEBA_2012__0122 bugfix         squid-3.1.10-1.el6_2.2.x86_64
i CEBA_2012__0470 bugfix         squid-3.1.10-1.el6_2.3.x86_64
i CEBA_2012__0557 bugfix         squid-3.1.10-1.el6_2.4.x86_64
i CEBA_2012__1290 bugfix         squid-3.1.10-9.el6_3.x86_64
i CESA_2013__0505 Moderate/Sec.  squid-3.1.10-16.el6.x86_64
i CEBA_2013__0985 bugfix         squid-3.1.10-18.el6_4.x86_64
i CEBA_2013__1396 bugfix         squid-3.1.10-19.el6_4.x86_64
i CEBA_2014__0048 bugfix         squid-3.1.10-20.el6_5.x86_64
i CESA_2014__0597 Moderate/Sec.  squid-3.1.10-20.el6_5.3.x86_64
i CESA_2014__1148 Important/Sec. squid-3.1.10-22.el6_5.x86_64
i CEBA_2014__1446 bugfix         squid-3.1.10-29.el6.x86_64
i CEBA_2015__1314 bugfix         squid-3.1.23-9.el6.x86_64
i CEBA_2016__0896 bugfix         squid-3.1.23-16.el6.x86_64
i CESA_2016__1138 Moderate/Sec.  squid-3.1.23-16.el6_8.4.x86_64
i CEBA_2016__1412 bugfix         squid-3.1.23-16.el6_8.5.x86_64
i CESA_2016__1573 Moderate/Sec.  squid-3.1.23-16.el6_8.6.x86_64
  1. When I try to get information for that errata there's nothing
yum update info CESA_2016__1573
--- NOTHING NOTHING NOTHING ---
  1. When I try to list all errata but grep that one I can see it
yum updateinfo info all | grep CESA_2016__1573 -B3 -A8
===============================================================================
  Moderate CentOS squid Security Update
===============================================================================
  Update ID : CESA_2016__1573
    Release : CentOS 6
       Type : security
     Status : stable
     Issued : 2016-08-04 12:51:39
Description : Moderate CentOS squid Security Update
   Severity : Moderate
  Installed : true

I would like to point out that I tested this scenario (downgrade/upgrade) on RHEL6 and it works. I also tried to install old version of squid package directly to avoid downgrade/upgrade sequence but the result was also the same. And the issue is not related to squid package only. Basically, I can reproduce the issue with any package. I also tried to clean yum cache after package downgrade but it doesn't help.

Any idea what could be wrong?!? Why is it marked as installed when it is actually not?!? When testing on RHEL6, I can see it is not installed and then, it is included in the list of packages to be updated.

Thanks for any answer.

  • could this not have something to do with info in the package cache? Prehaps between downgrade and patch steps, you should clean the cache? Not that this would make the situation better, but it might be that the package manager is reading two different states. – Bruce Becker Nov 4 '18 at 11:47

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