[Debconf-devel] Bug#1091701: debconf: bad error about unable to write templates.dat-new when there is no data to write

[Russell Coker]

Package: debconf
Version: 1.5.89
Severity: normal

I am writing SE Linux policy for the needrestart utility which runs the debconf
frontend program.

When it runs I see the following error message:
debconf: DbDriver "templatedb": could not write /var/cache/debconf/templates.dat-new: Permission denied

Firstly due to it's nature needrestart won't have anything to write to the
templates.dat file.

Next here is an extract from the strace output:
str.9334:openat(AT_FDCWD, "/var/cache/debconf/templates.dat", O_RDWR|O_CLOEXEC) = -1 EACCES (Permission denied)
str.9334:openat(AT_FDCWD, "/var/cache/debconf/templates.dat", O_RDONLY|O_CLOEXEC) = 4

So when it reads the data it sees that RDWR access isn't allowed, opens it
read-only and doesn't report this as an error.  So by then it should know
that writing is inappropriate as well as being unneeded and not report it
as a problem.

-- System Information:
Debian Release: trixie/sid
Architecture: amd64 (x86_64)

Kernel: Linux 6.12.6-amd64 (SMP w/4 CPU threads; PREEMPT)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU:en
Shell: /bin/sh linked to /usr/bin/dash
Init: unable to detect

debconf depends on no packages.

Versions of packages debconf recommends:
ii  apt           2.9.19
ii  apt-utils     2.9.19
ii  debconf-i18n  1.5.89

Versions of packages debconf suggests:
pn  debconf-doc                <none>
pn  debconf-kde-helper         <none>
pn  debconf-utils              <none>
pn  libgtk3-perl               <none>
pn  libnet-ldap-perl           <none>
pn  libterm-readline-gnu-perl  <none>
ii  perl                       5.40.0-8
ii  whiptail                   0.52.24-4

-- debconf-show failed