Weird Problem related to a Channel Security Exit

I posted the following weird channel security exit problem on the MQSeries ListServer.

I received a lot of emails (both public and private) offering help to the problem. Thanks. It was not an SELinux issue nor was it a corrupt shared library issue. It was an issue related to permissions for a mount point.

Here is the description to the problem followed by the solution:

I’ve got a really weird problem, that the internet seems to say that it is a permission issue with “/tmp” but I’m at a loss.

– Brand new: Red Hat Enterprise Linux Server release 7.6 (Maipo)
– Fresh install of MQ v9.1.0.1 64-bit

Installed MQAUSX into /var/mqm/exits64/ and yes it is a working version that works perfectly on other Linux distributions.

Here is the MQ error message:

08/02/19 12:46:45 - Process(51014.254) User(roger) Program(amqrmppa)
                    Host(someserver) Installation(Installation1)
                    VRMF(9.1.0.1) QMgr(MQA1)
                    Time(2019-02-08T11:46:45.514Z)
                    ArithInsert1(536895861)
                    CommentInsert1(/var/mqm/exits64/mqausx)
                    CommentInsert2(/var/mqm/exits64/mqausx: failed to map segment from shared object: Operation not permitted)
                    CommentInsert3(64)

AMQ6175E: The system could not dynamically load the shared library
'/var/mqm/exits64/mqausx'. The system returned error message
'/var/mqm/exits64/mqausx: failed to map segment from shared object: Operation
not permitted'.

EXPLANATION:
This message applies to UNIX systems. The shared library '/var/mqm/exits64/mqausx' 
failed to load correctly due to a problem with the library.

ACTION:
Check the file access permissions and that the file has not been corrupted.

“mqausx” is a standard Unix/Linux shared library (It is running on tons of Linux servers without issue). Even the “ldd” command gives a weird result:

$ ldd /var/mqm/exits64/mqausx
ldd: warning: you do not have execution permission for `/var/mqm/exits64/mqausx'
        not a dynamic executable

The permissions are set as follows:

chown mqm:mqm mqausx
chmod 750 mqausx

I even tried 777 for permissions. i.e.

-rwxrwxrwx  1 mqm  mqm  247087 Feb  7 15:11 mqausx

It still failed. Its a shared library, what is or how is a shared library “dynamic executable”?

Here is the solution that Josh suggested that worked:

First, issue the following command against your shared library:

$ df /var/mqm/exits64
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/aaa/bbb           5107712   3967288   1140424  78% /var/mqm

Use whatever is under “Mounted on” (i.e. /var/mqm – you may have something else like /var ) in the following command:

$ mount | grep /var/mqm

In my customer’s particular case, their mount point was on /var and the results of the command was:

/dev/aaa/bbb on /var type xfs (rw,nosuid,nodev,noexec,relatime,attr2,inode64,logbsize=256k,sunit=512,swidth=512,noquota)

The source of the issue was that the mount point had “noexec”permission. Hence, once that option was removed then everything went back to normal.

I hope this helps someone else in the future.

Regards,
Roger Lacroix
Capitalware Inc.