Emails Bounce Back when CageFS is Enabled (Proxyexecd issues)

Issue

• The users who have CageFS enabled have the 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 the CageFS, the autoresponders begin to work.

Solution

There could be several reasons why users with CageFS enabled have those problems. Here's the 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