[Proftpd-user] Wrong ordering of mod_auth_file and mod_sql breaks AuthFile user authentication

Hi,

I use both mod_sql and mod_auth_file for user authentication.

With the line below, authentication for both SQL and AuthFile users 
works.

     AuthOrder mod_sql.c mod_auth_file.c

With the line below, authentication for SQL users works, but is broken 
for AuthFile users.

     AuthOrder mod_auth_file.c mod_sql.c

When logging in with an AuthFile user, ProFTPD logs the following to 
SQLLogFile. `/var/lib/proftpd.db` is the database path specified in 
SQLConnectInfo.

     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: error opening SQLite 
database '/var/lib/proftpd.db': unable to open database file (No such 
file or directory)
     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: exiting    sqlite 
cmd_open
     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: exiting    sqlite 
cmd_select
     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: unrecoverable backend 
error
     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: error: 
'mod_sql_sqlite/0.4'
     2023-07-09 11:31:40,139 mod_sql/4.5[857014]: message: 'unable to 
open database file (No such file or directory)'

That is indeed what these syscalls return:

     [pid 857014] lstat("/var/lib/proftpd.db", 0x7ffc4f2c1db0) = -1 
ENOENT (No such file or directory)
     [pid 857014] getpid()                   = 857014
     [pid 857014] getpid()                   = 857014
     [pid 857014] openat(AT_FDCWD, "/var/lib/proftpd.db", 
O_RDWR|O_NOFOLLOW|O_CLOEXEC) = -1 ENOENT (No such file or directory)
     [pid 857014] openat(AT_FDCWD, "/var/lib/proftpd.db", 
O_RDONLY|O_NOFOLLOW|O_CLOEXEC) = -1 ENOENT (No such file or directory)

This happens because chroot() is called before the file is opened, as 
the config contains `DefaultRoot ~`. Therefore, the issue does not occur 
when that setting is absent.

A couple of things interest me:

- Why is the user looked up using mod_sql used when authenticating with 
a valid AuthUser? I would expect ProFTPD to exit on the first match, 
according to the AuthOrder. And with the 'broken' AuthOrder, AuthFile 
comes first.
- Why is chroot() called during authentication?

Met vriendelijke groeten,

William Edwards



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