Public Access
45525385330d8f832febf87dc541ddb747dde290
2
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 jaap-jan
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4552538533 |
Let the Linux head check for updates, and seal its device key in the TPM
Two things the RPM shipped without, and the reason they arrive together is
that both are the same question — what may this platform ask of the machine,
and what must it not ask of the user.
◆ UPDATES: THIS CLIENT CHECKS AND FETCHES, AND PACKAGEKIT INSTALLS.
ADR 0013 rule 11 said there was no updater at all, and that went too far. It
conflated noticing that a newer build exists with installing it: the second is
what the trust argument is about, and the first is not — a client that checks
a fixed address and tells you what it found has taken no capability from
anybody. Written as a flat refusal, the rule bought its safety by paying a cost
that was avoidable, and the ADR now says so in its own words.
So LinuxUpdateChannel reads the rolling nightly release, compares versions the
way rpm compares them, downloads the package, verifies its digest and hands the
file to PackageKit over gdbus. Polkit asks; the user may say no; nothing is
torn down before the answer, because ApplyingEndsTheProcess is false and the
shell already knows what that means — it is the phone's shape, and declining an
update must not cost somebody their open shells.
Three details that are load-bearing rather than incidental:
- The comparison is rpmvercmp and not SemVer, because rpm is what will accept
or refuse the install. Same argument ADR 0014 makes for versionCode. The
installed side is read out of the rpm database rather than derived from the
assembly, so the SemVer-to-rpm translation exists in exactly one place. All
28 expected values in RpmVersionTests came out of rpm itself rather than out
of a reading of the algorithm.
- The digest is checked and is not a signature. Velopack verifies its own
downloads and Android checks a signature; an RPM over HTTPS has neither. The
manifest names a SHA-256 and a mismatch deletes the file rather than leaving
something installable-by-hand in the profile directory.
- ONLY_TRUSTED is cleared, which is what routes the request to polkit's
package-install-untrusted action. The package is unsigned, so requiring
trust would fail every update at the last step.
◆ THE DEVICE KEY: SEALED IN THE TPM, BEHIND A PIN THE TPM CHECKS.
ADR 0007's amendment is the bar: a gate inside the process is not a gate. The
key is sealed into a TPM 2.0 keyedhash object whose userAuth comes from a PIN,
so unsealing is a command the chip refuses; the blob is encrypted to the storage
hierarchy and is useless on any other machine; nothing here ever compares a PIN.
The sealed object deliberately carries no NoDA attribute, and that one omission
is the whole reason four digits is enough: every wrong answer advances the TPM's
dictionary-attack counter and the chip stops answering entirely once it trips.
Measured at four wrong tries against a software TPM, after which the correct PIN
gets nothing either. It is asserted by a test rather than left to a reading of
the template, because removing the attribute leaves every other assertion
passing.
This is weaker than Hello and Touch ID and the difference is invisible, so it is
written down in three places rather than smoothed over: those raise their prompt
from inside the platform and this one is a window we draw. The prompt is
deliberately plain for that reason — teaching people that a convincing DodoSSH
PIN box is a system dialog is the one thing this design must not do.
Rejected, each for failing the amendment: the Secret Service API, which has no
per-use consent and is DPAPI's shape exactly; fprintd, which answers a question
and holds nothing, so skipping the call skips the gate; and a polkit-gated root
helper, which would work and puts a privileged component in a package that
installs nothing setuid.
Availability is narrower than "has a TPM": on Fedora /dev/tpmrm0 is root:tss and
desktop users are not in tss, so the ordinary case reports unavailable and keeps
asking for the passphrase. Shipping a udev rule to widen that is refused — it is
the administrator's decision, not an application package's.
◆ WHAT IS ACTUALLY VERIFIED, SINCE THAT IS THE PART THAT USUALLY ISN'T.
This is the only device key store in the repository with real coverage, and it
is only possible because the PIN is a delegate and the TPM is a device: seal,
unseal, wrong PIN, lockout, decline and a foreign blob all run unattended
against a software TPM. Windows and macOS cannot be tested at all — their
prompts block a suite forever, which WindowsDeviceKeyStoreTests records.
TSS.Net's own TcpTpmDevice cannot reach swtpm: it opens the platform socket too
and exchanges a handshake only the Microsoft reference simulator answers, so
Connect() blocks with no error and no timeout. SoftwareTpm speaks the data
channel and nothing else.
The suite also lied once and was fixed: the lockout test trips shared state, and
without a DictionaryAttackLockReset in Dispose every later test got null from a
correct PIN — six of them assert null and passed for entirely the wrong reason.
End to end on a real Fedora 44: a genuine linux-x64 publish packages, installs,
and every DT_NEEDED in the installed tree resolves except liblttng-ust, which is
the one this spec deliberately excludes. What no runner covers is /dev/tpmrm0,
PackageKit and polkit, and Phase 19 grew five checks for exactly those.
Also fixed: the magic-bytes literal picked up raw control characters, which made
LinuxDeviceKeyStore.cs binary to git — no diffs and no line-ending normalisation.
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jaap-jan
|
1bf79c7c26 |
Package the Linux desktop head as an RPM, and publish a nightly one
The third desktop platform shipped as nothing: a checkout somebody built.
VelopackUpdateChannel already named the two platforms it serves rather than
negating the one it does not, so that a Linux package would be an addition
there rather than something that had silently half-happened. This is it, and
it is deliberately not a Velopack channel.
There is no updater in the package at all. On this platform dnf is already an
updater the user trusts, audits and controls, and a second one answering to
this project instead is the capability ADR 0013 rule 4 spends a page keeping
unsettable. The cost is real and is written down rather than glossed: nothing
tells a Linux user that a newer build exists, because there is no repository
to tell them.
Rule 3 is untouched. The build job packages the release-shaped RPM on every
main build and every tag and uploads nothing, exactly as it does for Windows
and macOS; the desktop job packages the nightly-shaped one and puts it on the
rolling nightly-desktop release beside the Windows feed. Two RPMs with
different names owning different paths cannot replace one another, so rule 9's
separations come almost free here — the profile split still belongs to the
build, through DodoChannel.
vpk verifies that what it packs actually calls VelopackApp.Build().Run(), and
nothing here does that for us, so scripts/ci-linux-rpm.sh makes its own
assertions: it asks the finished package what it requires, what it provides,
what it holds and what modes those carry. Two of those checks exist because
the first realistic payload tripped them.
- .NET's libmscordbi.so links libmscordaccore.so. With bundled provides
excluded — which they must be, or this package would advertise libcoreclr
to the whole system — that produced a dependency no host on earth can
satisfy. The requires exclusion is computed from the payload rather than
listed, because a list of Microsoft's internal file names goes stale in
the direction that yields an uninstallable package.
- cp -a inherits the publish directory's modes, and off the wrong filesystem
that meant a world-writable /opt/DodoSSH: any local account able to
replace the SSH client every other account runs. For an application
holding a team's credentials in plaintext that is the trust model walked
around rather than attacked. Every mode is now set absolutely.
Verified as far as a runner can: both packages install side by side on Fedora
44, resolve webkit2gtk4.1 2.52.5 — the backend MainWindow records as measured
— keep separate launchers, icons and profiles, and dnf remove takes one tree
and leaves the other. 0.0.1~alpha.0.143 sorts below both 0.0.1 and the next
height. What no runner can answer is Phase 19, which is new and unwalked.
RHEL 9 is deliberately not claimed. It ships WebKitGTK's 4.0 line under
libwebkit2gtk-4.0.so.37, and an or-branch for it was written and then removed:
nobody has run the head there, and dnf refusing with "nothing provides
libwebkit2gtk-4.1.so.0" is a better answer than an install that draws a blank
terminal. Same sentence, and the same reason, as the missing Intel Mac.
x86_64 only, for that reason and not a different one.
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