Proxy file handling in gLExec

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gLExec uses four environment variables for various reasons. This section is intended to explain what they do in a pragmatic way so that you should be able to work with them.

The environment variables of interest are:

  • GLEXEC_CLIENT_CERT
  • X509_USER_PROXY
  • GLEXEC_SOURCE_PROXY
  • GLEXEC_TARGET_PROXY

Note: do NOT forget to export/setenv these variables, so that they are known to gLExec.

GLEXEC_CLIENT_CERT

gLExec uses this (proxy) certificate as input to know who to authorize and to which account a mapping must be done.

The GLEXEC_CLIENT_CERT

  • Contains an absolute file path to the proxyfile. Note: "/dir/subdir/../subdir2/proxy" is allowed.
  • The proxyfile MUST contain a public and private key pair.
  • The proxyfile MUST be readable by the user account calling gLExec.

File permissions

The file permissions of the file must meet the following:

  • The proxy MUST be owned by the identity that calls gLExec. In pilot job framework use cases: owned by the pilot user
  • The proxy MUST NOT exceed the file permissions of 0700 which means readable, writeable or executable explicitly for the user of the file. Groups, others and special bits are not allowed.

Troubleshooting hints for version < 0.6.9

When this environment variable is not available or when the given path is not readable by gLExec the following error messages will occur in the gLExec log indicating a problem with gLExec's input, in particular the absence of a usable GLEXEC_CLIENT_CERT: 

glexec[10301]: LCAS authorization request
glexec[10301]: lcas.mod-lcas_run_va(): Cannot find certificate chain in pem string(failure)
glexec[10301]: lcas.mod-lcas_run_va(): failed

As a result of not being able to present tokens to be authorized, the gLExec tool will exit with a 203 exit code. This indicates that the authorization of the user has failed.

For more information on the gLExec exit code, please visit: Exit codes of gLExec

X509_USER_PROXY (on the calling side)

The X509_USER_PROXY passes through gLExec to the SCAS client or Argus client LCMAPS plug-ins. In a Multi User Pilot Job (MUPJ) environment this proxy is owned by the Pilot Job Framework Production Manager a.k.a. the Pilot User..

For the interaction with an site central authorization service these credentials are used to contact the service. The credentials will be used in the policy decision at the service, but for the SCAS interaction this identity (by its VOMS credentials for instance) must be whitelisted to be able to interact with the service. The X509_USER_PROXY is used to setup the mutually authenticated secure channel to the authorization service.

The X509_USER_PROXY

  • Contains an absolute file path to the proxyfile. Note: "/dir/subdir/../subdir2/proxy" is allowed.
  • The proxyfile MUST contain a public and private key pair.
  • The proxyfile MUST be readable by the user account calling gLExec

Troubleshooting hints: using Argus

When this environment variable is not available or when the given path is not readable by gLExec the following error messages will occur in the gLExec log indicating a problem with LCMAPS plug-in's input, in particular the absence of a usable X509_USER_PROXY: 

lcmaps.mod-startPluginManager(): error initializing plugin: /opt/glite/lib64/modules/lcmaps_c_pep.mod 
lcmaps.mod-lcmaps_init() error: could not start plugin manager 
 Initialization of LCMAPS failed. Please check in syslog or the logfile for LCMAPS (when able to be opened) for more details

On the shell the exit code of gLExec will signal a 202. This indicates a system level error only resolvable by the System Administrator. This is not a true statement and a known bug in the LCMAPS plug-in C-PEP which will be resolved in the new release and changed to a 203 (authorization failed) error.

For more information on the gLExec exit code, please visit: Exit codes of gLExec

Troubleshooting hints: using SCAS

When this environment variable is not available or when the given path is not readable by gLExec the following error messages will occur in the gLExec log indicating a problem with LCMAPS plug-in's input, in particular the absence of a usable X509_USER_PROXY: 

lcmaps_plugin_scas_client-plugin_run(): No client side credentials for SSL handshake to the SCAS service presented. 
                                                 Not in the configuration file and not in the $X509_USER_{PROXY,CERT,KEY} environment variables. 
lcmaps_plugin_scas_client-plugin_run(): scas client plugin failed

On the shell the exit code of gLExec will signal a 203. This indicates an authorization failure.

For more information on the gLExec exit code, please visit: Exit codes of gLExec

GLEXEC_SOURCE_PROXY (optional)

gLExec has the capability of transferring the proxy file from the calling environment to the target user's environment. The resulting file will then be accessible by the target user. The GLEXEC_SOURCE_PROXY holds the path to the proxy file that needs to be transferred.

The setting is optional. If no GLEXEC_SOURCE_PROXY is present for gLExec to use, no proxy file is transferred (version: 0.6.8-3 and older).

When the GLEXEC_SOURCE_PROXY is set:

  • Contains a file path from the root to the file. Note: "/dir/subdir/../subdir2/proxy" is allowed.
  • Must be readable by the user account calling gLExec
  • Variable must be accessible by gLExec to read.
    • Typically that means to export it into the current shell.
  • Must be set before calling gLExec.

When the GLEXEC_TARGET_PROXY environment variable is not set, the proxy will be staged in a default location. The location is by default: <target user's $HOME>/.glexec/proxy. This location is override-able by using the GLEXEC_TARGET_PROXY.

As a result of the proper staging of the proxy file the X509_USER_PROXY environment variable will be set. The X509_USER_PROXY will be set to the path of the proxy file. This could be the default location <target user's $HOME>/.glexec/proxy or the value of GLEXEC_TARGET_PROXY.

File permissions

The file permissions of the file must meet the following:

  • The proxy MUST be owned by the identity that calls gLExec. In pilot job framework use cases: owned by the pilot user
  • The proxy MUST NOT exceed the file permissions of 0700 which means readable, writeable or executable explicitly for the user of the file. Groups, others and special bits are not allowed.

Troubleshooting hints

If the GLEXEC_SOURCE_PROXY is not set, gLExec will continue without it.

If the GLEXEC_SOURCE_PROXY is set, but the file is unreadable then the following message will occur on the commandline: 

[gLExec]:   The stat syscall returned with an error for either $GLEXEC_CLIENT_CERT or $GLEXEC_SOURCE_PROXY.

The gLExec exit code will be set to 201, which indicates a user (resolvable) error.

For more information on the gLExec exit code, please visit: Exit codes of gLExec

GLEXEC_TARGET_PROXY (optional)

The GLEXEC_TARGET_PROXY is the full path of the location where the GLEXEC_SOURCE_PROXY is going to be written. By default gLExec uses the path <target user's $HOME>/.glexec/proxy, but this can be changed by setting this environment option.

The path will be checked by gLExec to be assured that:

  • The directory in which the proxy will be written is owned by the target user.
  • Is writeable by the target user.

As a result of the proper staging of the proxy file the X509_USER_PROXY environment variable will have the same value as the set GLEXEC_TARGET_PROXY.

Troubleshooting hints

If gLExec is unable to write to the indicated target location a 201 exit code is returned by gLExec, indicating a user (resolvable) error.

For more information on the gLExec exit code, please visit: Exit codes of gLExec

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