Systemd sandboxing and connection sharing fixes

See merge request !56

Network sharing via connman does not work in all devices, legacy sharing
config not ivolving connman works in no devices. Part of the problem lies
in connman/kernel end (device type for rndis0 interface is not reported by
udev and/or connman developer mode plugin does not take connection sharing
mode into account), part is due to fragile / broken usb-moded side logic.

Stop usb-moded from making wifi / cellular power cycle requests.

When using legacy sharing config and cellular is not online, make an
attempt to share wlan connection (the connman way already does this).

Rewrite all D-Bus ipc logic and refactor the rest too.

Add error checks in select places so that usb-moded abandons failed
mode setting and falls back to charging only.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Using vanilla libdbus api for dealing with messages containing
variants and dict arrays can be cumbersome.

Add helper functionality to avoid complexity elsewhere.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Avoid literal buffer sizes, remove unnecessary trailing whitespace,
and use correct data types.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Attribute making it possible for gcc to check logging format strings
vs. arguments given got dropped at some stage.

Put __attribute__((format(printf,...))) back in.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

When logging to stderr from usb-moded systemd service (e.g. due to slightly
different logging format) block buffering is used and causes the messages
to appear out of sync vs other processes.

Flush stderr after each diagnostic message.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Compiler diagnostics have improved. Using PATH_MAX buffer sizes when
constructing paths with snprintf() and friends both makes sense and keeps
gcc happier.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Development time ini-file merge logging that got left in. Generates enough
noise to make debug logging useless for normal purposes.

Comment out uninteresting progress messages.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Attempting to remove a file from read-only filesystem yields
EROFS error even if the file does not exist. Which then leads
usb-moded complaining about not being able to remove a file
that does not exist.

Check that legacy config file /etc/usb-moded/usb-moded.ini
exist before attempting to remove it.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

The return value from system() is wait() like status value - not subprocess
exit code.

Fix return value handling and improve diagnostic output while at it.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Apparently refactoring from integer 0/-1 to boolean true/false
return value went slightly wrong - some call sites were not
adjusted accordingly.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Compiler warns about "const const".
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Usb-moded is running as root, with full capability set.

Define and use minimal set of capabilities required by usb-moded to
operate correctly on all supported devices.

Document further sandboxing actions that should be made, but are not
possible with the systemd version that is currently available in
sailfish.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Temporarily disabling generation of doxygen documentation can significantly
reduce time taken by full rebuilds. However, it also makes rpm build fail
due to not having any html documents to install / package after build step.

Produce empty doc package if no html files have been generated during
build step.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Fix alignment and tabulator issues.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Fedora packaging guidelines say:

The BuildRoot: tag, Group: tag, and %clean section SHOULD NOT be used.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Expand tabs, remove trailing spaces.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Doxygen outputs a lot of progress info to stdout - which easily
mages genuine build problems hard to spot.

Redirect progress info to a file to improve build log readability.

Remove generated html output and log files on clean-local target.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

A lot of source files are simply ignored by doxygen
due to missing/incorrect @file tags.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Limit dynamic modes to device owner

See merge request !55

Check sender uid to deny access for modes that are restricted. Prevent
non-owner users from hiding or unhiding modes. Add
get_allowed_modes_for_user method that lists only those methods that
user may choose.

Set last seen user based on uid that has called
get_allowed_modes_for_user last. This is not a perfect solution by any
means since it can be easily confused by calling it from command line as
root but generally no user other than the active one should call it.
Later when there is a proper way to get the active user this can be
improved.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Add method to set last seen user. Use that information to limit the
implicitly set modes. If no user has been seen yet, fallback to
charging only mode.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Add method to retrieve the uid of the sender process. This calls DBus
daemon synchronously.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Check for restricted modes in common_get_mode_list and don't return them
unless allowed. Add uid parameter to common_get_mode_list to do that.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Add usbmoded_is_mode_permitted function to check if user is allowed to
set given mode. Root is always allowed to set any mode. Non-dynamic
modes are always allowed for all users. Dynamic modes can be set if user
belongs to sailfish-system.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Add --enable-sailfish-access-control to configure.
Enable sailfish access control in %build.
Signed-off-by: Tomi Leppänen <tomi.leppanen@jolla.com>

Handle comma separated list of configfs functions

See merge request !54

In android-usb backend a comma separated list of functions to enabled
can be written as-is to sysfs control file. This assumption got inherited
by configfs backend, and things fall apart if a mode needs to activate
more than one function.

Split comma separated list of functions into an array and enable each
function separately.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Don't use %config(noreplace).

See merge request !53

[packaging] Update config as per policy. Contributes JB#44152
Signed-off-by: David Greaves <david.greaves@jolla.com>

Fix handling of fallback setting values

See merge request !50

For the purpose of preserving runtime modifications values in legacy
configuration files need to be given priority over new style static
configuration files. As a side effect this makes it impossible to
override default mode if it was done via defining mode=ask in the
legacy config file.

Ignore mode=ask if defined in a legacy config file.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Having developer is optional and requires configuration files to be
installed on the device. Thus defaulting to use developer mode in
absence of any configuration files makes little sense, and also causes
need for otherwise unnecessary configuration files in normal user
devices.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

Runtime configuration changes are saved as "delta to values defined in
static configuration". Handling default values separately from static
configuration can cause unexpected values to get stuck on save.

Seed static configuration data with assumed defaults to rectify behavior
of delta save logic.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>