The new 'unique' API allows listing all unique field values that a field
specified by a field name can take in all entries of the journal. This
allows answering queries such as "What units logged to the journal?",
"What hosts have logged into the journal?", "Which boot IDs have logged
into the journal?".
Ultimately this allows implementation of tools similar to lastlog based
on journal data.
Note that listing these field values will not work for journal files
created with older journald, as the field values are not indexed in
older files.
Among other cleanups this introduces a threshold for the size of binary
blobs we serialize as integer arrays in the JSON output. THis can be
disabled via --all.
The old code used a timestamp to print a timespan for unsealed journalfiles,
incorrectly showing things like 2230 days of unsealed entries. Print the timespan
between the first and last entry instead.
This requires a little bit of tip-toeing around to explicitly avoid
touching the environment from a sig handler. Instead, simply create a
function to reset the var to its "unset" state, allowing the next call
to columns() to recalculate and cache the new value.
This splits the JSON output mode into different modes: json and
json-pretty. The former printing one entry per line, the latter showing
JSON objects nicely indented and in multiple lines to make it easier to
read for humans.
Let's clean up our terminology a bit. New terminology:
FSS = Forward Secure Sealing
FSPRG = Forward Secure Pseudo-Random Generator
FSS is the combination of FSPRG and a HMAC.
Sealing = process of adding authentication tags to the journal.
Verification = process of checking authentication tags to the journal.
Sealing Key = The key used for adding authentication tags to the journal.
Verification Key = The key used for checking authentication tags of the journal.
Key pair = The pair of Sealing Key and Verification Key
Internally, the Sealing Key is the combination of the FSPRG State plus
change interval/start time.
Internally, the Verification Key is the combination of the FSPRG Seed
plus change interval/start time.
This adds forward-secure authentication of journal files. This patch
includes key generation as well as tagging of journal files,
Verification of journal files will be added in a later patch.
