We'd like to measure various additional things into PCRs, but all
available ones to the OS are already used for various purposes. Hence,
let's introduce a new concept of "NV Index based PCRs", i.e. let's use
TPM2 nv indexes of type TPM2_NT_EXTEND that mostly behave like real
PCRs, but which we can allocate relatively freely from the nv index
space. Let's call these "fake" PCRs "NvPCRs".
My original intention was to get a fixed NV index range assigned from
the TCG, either for Linux or for systemd as a project, but this stalled
with no further updates from the TCG for more than a year and a half
now. I was told an NV index range to use though, even if it never was
officially assigned, hence this PR uses this by default. But the range
is configurable at build time, on purpose, so that downstreams have some
flexibility to change this if they want. To abstract the actual nvindex
number away we introduce a naming concept, so that nvindexes are
referenced by name string rather than number.
NvPCRs are defined in little JSON snippets in /usr/lib/nvpcr/*.nvpcr,
that match up index number and name, as well as pick a hash algorithm.
There's one complication: these nvindex (like any nvindex) can be
deleted by anyone with access to the TPM, and then be recreated. This
could be used to reset the NvPCRs to zero during runtime, which defeats
the whole point of them. Our way out: we measure a secret as first thing
after creation into the NvPCRs. (Or actually, we measure a per-NvPCR
secret we derive from a system secret via an HMAC of the NvPCR name) and
the nvindex handle). This "anchoring" secret is stored in /run/ +
/var/lib/ + ESP/XBOOTLDR (the latter encrypted as credential, locked to
the TPM), to make it available at the whole runtime of the OS.
We can use this to remove any kind of nvindex, hence give it a generic
name.
Also instead of passing "NONE" as session if none is specified, pass
PASSWORD instead, so that the function actually becomes useful if no
session is specified (the only user so far, pcrlock always provides a
session, hence this is no change in behaviour).
We soon want to add the ability to extend into nvindexes in addition to
PCRs, hence rename the function to make clear it is about pcr extension.
While we are at it, switch things over to "struct iovec" as we generally
try to do it now in tpm2-util.[ch] these days.
Make the systemd-pcrlock tool compatible with TCG CEL records that
encode measurements into nvindexes rather than PCRs.
This doesn't add code for actually predicting them, but just makes sure
we can parse them correctly and display them reasonably.
If UINT32_MAX is passed in the PCR masks pick some reasonable defaults
in encrypt_credential_and_warn().
These defaults copy what "systemd-creds encrypt" uses. By adding these
defaults to the internal functions any user of them can take benefit of
them.
This reworkds TPM2 based creds a bit. Instead of mapping the key type
"tpm2" directly to a TPM2 key without PK, let's map it to an "automatic"
key type that either picks PK or doesn't, depending on what's available.
That should make things easier to grok for people, as the nitty gritty
details of PK or not PK are made autmatic. Moreover it gives us more
leverage to change the TPM2 enrollment types later (for example, we
definitely want to start pinning SRK, and hook up pcrlock too, for
creds, which we currently don't).
This hence adds a new _CRED_AUTO_TPM2
pseudo-type we automatically maps to CRED_AES256_GCM_BY_TPM2_HMAC_WITH_PK
or CRED_AES256_GCM_BY_TPM2_HMAC depending if PK as available. Similar,
_CRED_AUTO_HOST_AND_TPM2 is added, which does the same for the
host/nonhost cred type.
This does not introduce any new type on the wire, it just changes how we
select the right key type.
To make the code more readable this also adds some categorization macros
for the keys, instead of repeating the list of key types at multiple
places.
Over the time, the functionality in ukify has grown. This should all be briefly
mentioned in the first section so the user does't have to read the whole page
to figure out what types of functionality are implemnted.
Also add an example of direct kernel boot. It's a nifty technology (and frankly
underutilized, considering how cool it is is).
Unfortunately qemu still default to BIOS boot, so for the direct kernel
boot with an efi file to be of any use, the complex param used to switch
to UEFI mode needs to be provided.
Also add some links to qemu and OVMF.
In btrfs-progs 6.15 it is planned to add a new parameter in mkfs.btrfs
--inode-flags, that can set attributes for subvolumes, directories, and
files.
The current supported attributes are "nodatacow", to disable CoW, and
"nodatasum", to disable the checksum.
This commit extend the "Subvolunes=" option to understand the
"nodatacow" flag for subvolums only.
If RepartOffline is enabled it will build the image without loopback
devices, using the correct --inode-flags parameters.
If RepartOffline is disabled it will use loopback devices and set the
btrfs attributes accordingly.
Signed-off-by: Alberto Planas <aplanas@suse.com>
These three functions are currently only used by sbsign, which requires
OpenSSL. Moreover, pe_hash() and uki_hash() anyway do not work if
OpenSSL is disabled. Let's only declare them when OpenSSL support is
enabled.
This has been tripping up container manager people. let's document this
explicitly.
(Note that the container interface could really use some updates, i.e.
it was written before a time where cgroup namespacing was a thing. But I
am too lazy to fix that now, so let's just add this once facet.)
Type `simple` explicitly mentions that invocation failures like a missing binary
or `User=` name won’t get detected – whereas type `exec` mentions that it does.
Type `oneshot` refers to being similar to `simple`, which could lead one to
assume it doesn’t detect such invocation failures either – it seems however it
does.
Indicate this my changing its wording to be similar to `exec`.
Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
