This issue with libpam predates mysql 5.7.  It's present in trusty's vsftpd 3.0.2-1ubuntu2.14.04.1, mysql 5.5.54-0ubuntu0.14.04.1, and the standard libpam package.  My workaround last year when I encountered the issue was to remove both vsftpd and libpam-mysql from the default repos and to manually install vsdfpd from 

http://dinofly.com/files/linux/vsftpd_3.0.2-1ubuntu2_amd64.deb

https://ubuntuforums.org/archive/index.php/t-2218804.html is the spot where I found this fix a year ago.  I've been waiting for an official fix ever since but if one has been released, I missed it.  I'm still running this custom version.

It is entirely possible that the bug I'm experiencing with 5.5 is different but related to what is causing the problem covered in 1574900, but as the symptoms seem to be identical, I tend to assume it is the same bug.

The host involved here is my employer's primary public ftp server where we give 3rd parties (customers, contractors, etc) the ability to upload large files and we have a simple mysql db where their virtual users are kept.  If you need a guinea pig host for testing, I can easily spin up a clone of this system for testing purposes.


-----Original Message-----
From: <email address hidden> [mailto:<email address hidden>] On Behalf Of Nish Aravamudan
Sent: Monday, March 20, 2017 11:56 AM
To: Joi L. Ellis <email address hidden>
Subject: [Bug 1574900] Re: libpam-mysql undefined symbol: make_scrambled_password

@jlellis: There is no MySQL  5.7 in Trusty. Are you using a PPA? Or are you saying that MySQL 5.5 also has this problem?

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https://bugs.launchpad.net/bugs/1574900

Title:
  libpam-mysql undefined symbol: make_scrambled_password

Status in pam-mysql package in Ubuntu:
  Fix Released
Status in pam-mysql source package in Xenial:
  Fix Committed
Status in pam-mysql source package in Yakkety:
  Fix Committed
Status in pam-mysql package in Fedora:
  Unknown

Bug description:
  [Impact]

   * libpam-mysql is unable to be used because of an upstream symbol
  change in libmysqlclient.

   * Upstream libpam-mysql has fixed this by updating the source to use
  the now-exported API.

  [Test Case]

  Steps to reproduce (with vsftpd): 
  Installation requirements: mysqlserver 5.7.x, libpam-mysql, vsftpd

  create vsftpd user: 
  useradd --home /home/vsftpd --gid nogroup -m --shell /bin/false vsftpd

  create mysql database and user: 
  == // Start SQL
      
      CREATE DATABASE vsftpd;
      GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP ON vsftpd.* TO 'vsftpd'@'localhost' IDENTIFIED BY 'ftpdpass';
      GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP ON vsftpd.* TO 'vsftpd'@'localhost.localdomain' IDENTIFIED BY 'ftpdpass';
      FLUSH PRIVILEGES;

      USE vsftpd;

      CREATE TABLE `accounts` (
        `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
        `username` VARCHAR( 30 ) NOT NULL ,
        `pass` VARCHAR( 50 ) NOT NULL ,
      UNIQUE (
        `username`
      ));
      insert into accounts(username,pass) values('user',password('password'));

  ==// End SQL

  Configure PAM: 
  insert into /etc/pam.d/vsftpd: 

      auth required pam_mysql.so verbose=1 user=vsftpd host=localhost db=vsftpd table=accounts usercolumn=username passwdcolumn=pass crypt=3 passwd=ftpdpass
      account required pam_mysql.so verbose=1 user=vsftpd host=localhost db=vsftpd table=accounts usercolumn=username passwdcolumn=pass crypt=3 passwd=ftpdpass

  Configure vsftpd (/etc/vsftpd.conf) :

      listen=YES
      anonymous_enable=NO
      local_enable=YES
      write_enable=YES
      local_umask=022
      dirmessage_enable=YES
      xferlog_enable=YES
      connect_from_port_20=YES
      nopriv_user=vsftpd
      chroot_local_user=YES
      secure_chroot_dir=/var/run/vsftpd
      pam_service_name=vsftpd
      guest_enable=YES
      guest_username=vsftpd
      local_root=/home/vsftpd/$USER
      user_sub_token=$USER
      virtual_use_local_privs=YES

  restart vsftpd:
   /etc/init.d/vsftpd restart
  check /var/log/auth.log

  [Regression Potential]

   * There is currently no fix or workaround, as the library is
  basically broken as installed from Ubuntu.

   * I believe the regression potential to be very low because the
  current code does not work.

  ---

  In Ubuntu 16.04, the libpam-mysql package does not work.  It crashes
  with the below error:

  PAM unable to dlopen(pam_mysql.so): /lib/security/pam_mysql.so:
  undefined symbol: make_scrambled_password

  I fixed this issue by download the source for the package and applying
  the patches that come from this source RPM:

  http://dinofly.com/files/linux/pam_mysql-0.7-0.20.rc1.fc23.src.rpm

  I then created unofficial packages after applying the patch.  They can
  be downloaded here:

  http://www.dinofly.com/files/linux/libpam-mysql_0.7~RC1-4ubuntu3_amd64.deb
  http://www.dinofly.com/files/linux/libpam-mysql_0.7~RC1-4ubuntu3_i386.deb

  libpam-mysql now works again on Ubuntu 16.04 x86 and x64.

  Here is the initial RedHat bug report:

  https://bugzilla.redhat.com/show_bug.cgi?id=709534

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