Postfix module - Mailman wrapper - Couldn't write data/aliases.db and data/virtual-mailman.db files
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
GNU Mailman |
Fix Released
|
Medium
|
Mark Sapiro | ||
mailman (Debian) |
Fix Released
|
Undecided
|
Unassigned | ||
mailman (Ubuntu) |
Fix Released
|
Low
|
Unassigned | ||
Xenial |
Won't Fix
|
Undecided
|
Unassigned | ||
Zesty |
Won't Fix
|
Undecided
|
Unassigned | ||
Artful |
Won't Fix
|
Undecided
|
Unassigned |
Bug Description
Dear project leader
At least in version 2.1.23, there is a bug regarding permissions set for Mailman data/aliases table and Mailman data/virtual-
Here I describe the current behavior for the Mailman data/aliases table only but the problem is identical for the Mailman data/virtual-
In order, the following conditions have to be met:
- Postfix need read access to the aliases.db file
- Mailman like to be owner of those files and the Mailman group needs write access to them
I. Postfix needs a read access to the aliases.db file
We can either set permissions as 0660 and add postfix user to mailman group (what I've done), or set the permissions as 0664
II. Mailman group needs a write access to those files at any time
The following behavior has been observed:
When creating a new list on command line, using bin/newlist script as follow:
# newlist -u virtualhost foobar
the files will be created as follow:
-rw-rw---- 1 root list aliases
-rw-r----- 1 root list aliases.db
The same thing has been observed when recreating the file from scratch using bin/genaliases:
-rw-rw---- 1 root list aliases
-rw-r----- 1 root list aliases.db
Note that in both cases, files were not present. Thus, they were created from scratch.
As you can see here, the Mailman data/aliases file is created with the expected group and permissions but the data/aliases.db file is only writable by owner. From the POSTALIAS(1) command point of view, that is the expected behavior: The file is created with the same group and other read permissions as their source file.
The problem here is that with those permissions, creating a list through Mailman interface later on will result in a permissions denied error because the Mailman group, through the wrapper, cannot write (update) the aliases.db file (no write permissions).
That is really a problem. Of course, one can just pre-create the files as follow:
# cd /var/lib/mailman
# sg list -c "touch data/aliases && postalias data/aliases"
# chmod 0660 data/aliases*
but that seem tedious. What if at some point (for any reason), the files get recreated from scratch?
So, from my point of view, the MTA/Postfix.py module should always set correct permissions on *.db file, to be sure that Mailman group has write permissions, at least when the files are created from scratch. Eg:
IF NOT EXISTS aliases:
Touch data/aliases data/aliases.db with correct permissions (066x)
Add alias entries into aliases as usually
Run POSTALIAS(1) command as usually
Then, we are fine.
Thank you.
Related branches
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Changed in mailman: | |
status: | Fix Committed → Fix Released |
There is another issue not mentioned in the original report and that is that aliases.db must be owned by the Mailman user so Postfix runs the pipe as the Mailman user and group.
bin/check_perms would check/fix this and also ensure the mode is at least 0660, but I've gone a step further and now ensure these things at the time the postalias and postmap commands are run and also ensure the mode is at least 0664 so Postfix doesn't need to be in Mailman's group.