Emails Bounce Back when CageFS is Enabled (Proxyexecd issues)

Issue

• The users who have CageFS enabled have an issue with the mail pipe - their emails are bounced back: 

  ------ pipe to |/usr/local/cpanel/bin/autorespond 
  <mailto:[e-mail]> [e-mail]
  /home/user1/.autorespond
  
  generated by <mailto:[e-mail]> 
  [e-mail] ------
  
  You are not authorized to run this command

• You can see the following errors in email logs:

  2020-04-12 21:49:46 1f6jA9-004Fzw-OF ** |/usr/local/cpanel/bin/autorespond [e-mail] /home/user1/.autorespond ([e-mail]) <[e-mail]> R=virtual_aliases_nostar T=cagefs_virtual_address_pipe: Child process of cagefs_virtual_address_pipe transport returned 1 from command: /bin/cagefs_enter 
  2020-04-12 21:49:46 cwd=/var/spool/exim 7 args: /usr/sbin/exim -t -oem -oi -f <> -E1f6jA9-004Fzw-OF 
  2020-04-12 21:49:46 1f6jAA-004G13-Ab <= <> R=1f6jA9-004Fzw-OF U=mailnull P=local S=6651 T="Mail delivery failed: returning message to sender" for [e-mail]

• If you disable CageFS, the autoresponders start working.

Solution

There could be several reasons why users with CageFS enabled have those problems. Here's a list of the most common issues that cause it.

1.  Make sure that the proxyexecd service is running:

   # service proxyexecd status

   If it doesn't work, start the service:

   # service proxyexecd start

2. The /etc/cagefs/proxy.commands file should contain the following entries:

   # cat /etc/cagefs/proxy.commands | grep send
   SENDMAIL=/usr/sbin/sendmail
   SENDMAILQ=/var/qmail/bin/sendmail
   SENDMAILS=/usr/sbin/sendmail.sendmail
   SENDMAIL_CPANEL=/usr/local/cpanel/bin/sendmail

   If your /etc/cagefs/proxy.commands file doesn't have the lines above, add those lines and restart the proxyexecd service:

   # service proxyexecd restart

3. Check the permissions for the following directories "/usr/sbin", "/usr/bin/" and "/bin":

   # ls -ld /usr/sbin
   drwxr-xr-x. 3 root root 16384 Apr 11 02:36 /usr/sbin/
   # ls -ld /usr/bin
   drwxr-xr-x. 3 root root 40960 Apr 11 02:36 /usr/bin/
   # ls -ld /bin/
   drwxr-xr-x. 2 root root 4096 Apr 14 00:25 /bin

   If you see permissions other than 755, change them to 755 and update the CageFS skeleton:

   # chmod 755 /directory/filename
   # cagefsctl --force-update

4. If you still have the issue, try to remove the .cagefs.token file:

   # rm /var/cagefs/$(cagefsctl --getprefix USERNAME)/USERNAME/.cagefs/.cagefs.token

   Then, apply the changes:

   # cagefsctl --update-etc
   # cagefsctl --remount-all

5. In rare cases, the issue can be related to the ".proxyexec.log" file with incorrect data. Please check:

   # find /var/cagefs -name '.proxy*' | xargs file

   If there is no issue with ".proxyexec.log" files, then you should see the output like this:

   /var/cagefs/XX/user1/.proxyexec.log.lock: empty
   /var/cagefs/XX/user1/.proxyexec.log: data 

   • In case of the incorrect ".proxyexec.log" file, the output will look like this:

     /var/cagefs/XX/user2/.proxyexec.log.lock: empty
     /var/cagefs/XX/user2/.proxyexec.log: ASCII text, with very long lines, with no line terminators

     To fix that, remove the file:

     rm /var/cagefs/$(cagefsctl --getprefix USERNAME)/USERNAME/.proxyexec.log

   • In case you received such an error:

     /usr/sbin/sendmail: line 33: /usr/sbin/proxyexec: No such file or directory

     Reinstall the bsock package:

     # yum reinstall bsock

     and update CageFS:

     # cagefsctl --force-update && cagefsctl -M

Note: In case you stumble upon this last issue described in this article, contact our Support Team for further investigation and finding out the root cause. Feel free to contact us here: https://cloudlinux.zendesk.com/hc/requests/new