This matches the change to tpm2_seal(), which now accepts a Tpm2Context instead
of a device string.
This also allows using the same TPM context for sealing and unsealing, which
will be required by (future) test code when sealing/unsealing using a transient
key.
Because most TPM2 functions here are 'library-like' functions, they should be
at debug level, not error level.
The only functions not reduced to logging at debug are tpm2_list_devices(),
since it is expected to print output, and the tpm2_parse_pcr_argument_*()
functions, since the system-wide parse_*_argument() functions generally log at
error level.
Let's say "uki" rather than "stub", since that is just too generic, and
we shouldn't limit us to our own stub anyway, but generally define a
concept of a "measured UKI", which is a UKI that measures its part to
PCR 11.
This is mostly preparation for exposing this check to the user via
ConditionSecurity=.
Build targets should have a link dependency on the version scripts they
use. This also uses absolute paths in anticipation for meson 1.3
needlessly deprecating file to string conversions.
This was requested, though I think an issue was never filed. If people are
supposed to invoke it, even for testing, then it's reasonable to make it
"public".
All public programs are expected to have that. The --help output is adjusted to
follow the usual style (highlighting, listing of options). The OPTIONS
positional argument is renamed to "CONFIG", because we now also have "OPTIONS…"
to describe the non-positional options.
Previously we only logged our measurements to the journal. This is not a
great solution though, since regular logs are subject to rotation, which
is something we really cannot have for measurements (as it means we can
never reproduce the PCR values from the data). Hence, let's maintain an
explicit log.
Ideally, we'd just use the TCG Canonical Event Log format 1:1
(https://trustedcomputinggroup.org/resource/canonical-event-log-format/).
However it's not a perfect fit fo us, for various reasons. But let's
follow it (in its JSON incantation) as closely at it makes sense, so
that it can easily be converted to the full format by programs consuming
it.
Code comments explain where we deviate from the TCG CEL-JSON, and what
to do about it when reading the data.
I always found it confusing that most of our TPM related definitions are
in tpm2-util.h, but the PCR names in tpm-pcr.h, without the "2". Let's
fix that and make this systematic, in particular as the definitions in
the file all start with TPM2_ already.
No code flow changes, just some renaming.
We so far maintained two places for symboic names for PCRs. One in
tpm2-util.h and one in tpm-pcr.h.
Let's unify this into one, i.e. move the full list from tpm2-util.h into
tpm-pcr.h, replacing the short list placed so far there.
Systematically prefix the definitions with TPM2_ or tpm2_, to follow how
we do this for all other defines in this context.
No change in behaviour, just unification of tables.
In order to allow users to specify expected PCR values, change the
tpm2_parse_pcr_argument() to parse the text argument into an array of
Tpm2PCRValue objects, which provide not only the selected PCR indexes, but also
(optionally) the hash algorithm and hash value for each PCR index.
Add a new struct that can represent a PCR index, hash, and value all
together. This replaces code (e.g. the tpm2_pcr_read() parameters) that
required using both a TPML_PCR_SELECTION as well as array of TPM2B_DIGEST
entries, which was difficult to correlate the selection hash/index to each
digest.
Given that ERRNO_IS_NOT_SUPPORTED() also matches positive values,
make sure this macro is not called with arguments that do not have
errno semantics.
In this case the argument passed to ERRNO_IS_NOT_SUPPORTED() is the
value returned by find_tpm2_auto_data() which is not expected to return
any positive values, but let's be consistent anyway and move the
ERRNO_IS_NOT_SUPPORTED() invocation to the branch where
the return value is known to be negative.
Remove _cleanup_tpm2_context_ and _cleanup_tpm2_handle_ macros, replacing their
use with _cleanup_(tpm2_context_unrefp) and _cleanup_(tpm2_handle_freep),
respectively.
With these settings we intend to turn off timeouts for possibly
interactive/slow commands. The officially documented way to turn off the
time-outs is to setting them to infinity. So far we set them to zero
here though.
This lead to some confusiong, for example #18224. Let's fix this by
uniformly spelling out TimeoutSec=infinity.
This doesn't change behaviour. It just makes our generated files match
what we document, without relying on historic compat support.
Fixes: #18224
Both should have the same effect: the /dev/loop-control devices should
become available. systemd-tmpfiles-setup-dev.service creates the device
node "dry" based on modalias data, while modprobe@loop.service creates
it fully, because the module backing it is loaded properly. This should
shorten the deps chain a bit, simplify things and allows us to focus on
the stuff we actually need (i.e. the loopback infra) instead of all
entrypoints anyone might possibly need (i.e. the device nodes)
Let's imply "x-initrd.attach" for "usr" and "root" volumes, so that
we do not attempt to umount them anymore during shutdown.
The names of these volumes have been mandated by the Discoverable
Partition Spec:
https://uapi-group.org/specifications/specs/discoverable_partitions_specification/#suggested-mode-of-operation
Hence it appears reasonably safe to special case these volume names.
Note that a similar logic is implemented in fstab-generator and in fact
PID 1 to treat the root mount and /usr/ mount specially too, to avoid
trying to umount it at shutdown. (This is what fstab_is_extrinsic()
checks).
This should ensure that if /usr/ or / is for some reason a LUKS medium
we won't try to detach it during runtime, which likely fails, since we
run off it.
Note this also moves an ordering dep towards umount.target under the
x-initrd.attach check, becasue that's where the crucial conflicts dep is
placed too.
Prevent attackers from spoofing the tpmKey portion of the AuthSession by
adding a trusted key to the LUKS header metadata. Also, use a persistent
object rather than a transient object.
This provides the following benifits:
1. No way to MITM the tpmKey portion of the session, see [1] for
details.
2. Strengthens the encrypted sessions, note that the bindKey could be
dropped now.
3. Speed, once it's created we just use it.
4. Owner Auth is needed to call create primary, so using the SRK
creates a scratch space for normal users.
This is a "first to set" model, in where the first person to set the key
in the LUKS header wins. Thus, setup should be done in a known good
state. If an SRK, which is a primary key at a special persistent
address, is found, it will use whatever is there. If not, it creates an
SRK. The SRK follows the convetions used through the tpm2-software
organization code on GitHub [2], however, a split has occured between
Windows and Linux with respect to SRK templates. The Linux SRK is
generated with the unique field size set to 0, in Windows, it properly
sets the size to key size in bytes and the unique data to all 0's of that
size. Note the proper templates for SRKs is covered in spec [3].
However, the most important thing, is that both SRKs are passwordless,
and thus they should be interchangable. If Windows is the first to make
the SRK, systemd will gladly accept it and vice-versa.
1. Without the bindKey being utilized, an attacker was able to intercept
this and fake a key, thus being able to decrypt and encrypt traffic as
needed. Introduction of the bindKey strengthened this, but allows for
the attacker to brute force AES128CFB using pin guesses. Introduction of
the salt increases the difficulty of this attack as well as DA attacks
on the TPM objects itself.
2. https://github.com/tpm2-software
3. https://trustedcomputinggroup.org/wp-content/uploads/TCG-TPM-v2.0-Provisioning-Guidance-Published-v1r1.pdfFixes: #20668Fixes: #22637
Signed-off-by: William Roberts <william.c.roberts@intel.com>
Salt was added in v253. We are not checking whether it was actually found
(non-zero size), so when an old tpm+pin enrollment is opened things go boom.
For good measure, check both the buffer and the size in both places.
Assertion 'saltlen > 0' failed at src/shared/tpm2-util.c:2490, function tpm2_util_pbkdf2_hmac_sha256(). Aborting.
This will be used by Tpm2Handle instances, which is added in later patches.
The refcounting allows the context to be retained until all Tpm2Handles have
been cleaned up, and the initial ref is released, before cleaning the context.
The 'pcr_bank' functions operate on hash algs, and are not specific to the PCR
banks, while the 'primary_alg' functions operate on asymmetric algs, and are
not specific to primary keys.
When compiled without ENABLE_EFI, efi_stub_measured() was not defined, so
compilation would fail. But it's not enough to add a stub that returns
-EOPNOTSUPP. We call this function in various places and usually print the error
at warning or error level, so we'd print a confusing message. We also can't add
a stub that always returns 0, because then we'd print a message like "Kernel
stub did not measure", which would be confusing too. Adding special handling for
-EOPNOTSUPP in every caller is also unattractive. So instead efi_stub_measured()
is reworked to log the warning or error internally, and such logging is removed
from the callers, and a stub is added that logs a custom message.
Add a salt to the pin and store it in the TPM2 LUKS header for future
this. This adds entropy to user supplied pins and helps brute forcing
the passphrase on the key residing in the TPM or brute forcing bind key
encrypted sessions with low entropy passphrases.
Signed-off-by: malikabhi05 <abhishek.malik@intel.com>
Signed-off-by: William Roberts <william.c.roberts@intel.com>
Let's introduce a common implementation of a function that checks
whether we are booted on a kernel with systemd-stub that has TPM PCR
measurements enabled. Do our own userspace measurements only if we
detect that.
PCRs are scarce and most likely there are projects which already make
use of them in other ways. Hence, instead of blindly stepping into their
territory let's conditionalize things so that people have to explicitly
buy into our PCR assignments before we start measuring things into them.
Specifically bind everything to an UKI that reported measurements.
This was previously already implemented in systemd-pcrphase, but with
this change we expand this to all tools that process PCR measurement
settings.
The env var to override the check is renamed to SYSTEMD_FORCE_MEASURE,
to make it more generic (since we'll use it at multiple places now).
This is not a compat break, since the original env var for that was not
included in any stable release yet.
