The new unit is nice, but it might not be appropriate in all scenarios. It
requires a new kernel, which might be known to not be available, and also
changes sysctl kernel.core_pattern at runtime, which might not be desired.
Replace static enablement by a normal [Install] section and add the unit
to presets to enable it by default.
The awkward instructions in the man page are simplified and adjusted.
The PolicyPCR digest is not always the complete input to an offline
signature. PolicyAuthorize also includes the hashed policy reference.
This is now required for NVPCRs to work in the initrd.
Expose the complete data as "tbs" (to-be-signed) and use it when ukify
matches offline signatures. Keep "pol" as the compatibility fallback.
Fixes: https://github.com/systemd/systemd/issues/43635
Follow-up for f0f3687700
When --sign-initrd-pcrs is used with --policy-digest, generate the
extra enter-initrd policy with the "initrd" policy reference. This
matches the policy produced when ukify signs with a private key.
Fixes building UKIs with offline signing (e.g.: on OBS) and using
NVPCRs.
Follow-up for f0f3687700
Since the D-Bus DNS-SD API was introduced in c3036641f0ed (v236),
`RegisterService()` has created an `sd_bus_track` object to destroy the
registered service when the registering client disconnects from the bus.
However, the track object is a `_cleanup_(sd_bus_track_unrefp)` local in
`bus_method_register_service()` that is never stored anywhere, so it is
destroyed again as soon as the method handler returns. The vanish
handler (`dnssd_registered_service_on_bus_track()`) has thus been dead
code for the past ~8 years.
The observable effect: services registered via D-Bus silently persist
after the client disconnects — unowned, advertised until resolved exits,
and impossible to re-register since the identifier stays taken
(`DNSSD_SERVICE_EXISTS`). At the same time, the registration doesn't
survive a resolved restart, so the current behavior is neither reliably
ephemeral nor reliably persistent. Noticed while reviewing a project
that (unknowingly relying on this bug) registers a service with a
one-shot `gdbus call` and expects it to persist.
This PR:
1. splits the goodbye/zone-removal logic out of
`bus_dnssd_method_unregister()` into a helper — the vanish path needs
the full teardown, not just `dnssd_registered_service_free()`, which
would leave the service's RRs published in the per-link mDNS zones;
2. stores the track object in `DnssdRegisteredService`, making client
tracking work as originally intended;
3. documents the lifetime semantics in `org.freedesktop.resolve1(5)`
(matching the equivalent Avahi D-Bus API, whose entry groups are
likewise bound to the client connection) and points to `*.dnssd` files
for registrations independent of a client's lifetime;
4. adds a TEST-75 case covering the connection-bound lifetime.
Note this is a behavioral change for fire-and-forget clients (one-shot
`busctl`/`gdbus` invocations). Arguably those were never working
reliably (registrations silently vanished on any resolved restart, and
stale entries blocked re-registration), but if this is deemed too risky,
the alternative would be to drop the dead tracking code and codify the
persist-until-exit behavior instead — I'd argue tracking as originally
intended is the better contract.
Verification: code compiles; the new integration test is included.
Since the D-Bus DNS-SD API was introduced in c3036641f0 ("resolved:
implement D-Bus API for DNS-SD", v236), RegisterService() has set up an
sd_bus_track object so that a registered service is destroyed when the
client that registered it disconnects from the bus — there's even a
handler logging "Client of active request vanished, destroying DNS-SD
service."
However, the track object was never stored anywhere: it is declared as
a _cleanup_(sd_bus_track_unrefp) local in bus_method_register_service()
and hence destroyed again when the method handler returns, taking the
tracking down with it. The vanish handler was thus dead code, and
services registered via D-Bus silently persisted after their client
disconnected — unowned, impossible to re-register (the identifier
stays taken, failing with DNSSD_SERVICE_EXISTS), and advertised until
systemd-resolved itself exited.
Store the track object in DnssdRegisteredService, pinning it for the
lifetime of the service, so that client tracking works as originally
intended. Route the vanish path through the full unregistration logic
(goodbye packets + removal from the per-link mDNS zones), since freeing
the service alone would leave its RRs published in the zones.
Note for fire-and-forget clients (e.g. one-shot busctl/gdbus calls):
these were never reliable — the registration silently vanished on any
resolved restart — and now behave as documented for the corresponding
Avahi API as well: the bus connection must be kept open for as long as
the service is to remain registered. Document that in the man page and
NEWS, and point to *.dnssd files for registrations independent of a
client's lifetime.
Describe the system-wide W^X rule and the new proc_mem.force_override=never
and seccomp prerequisites, and drop the advice to block writable and
executable mappings by other means, which the policy now does itself.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
The petnames wordlist added in [1] is Apache-2.0 and this
causes problems with the distribution of systemd as the
GPL-2 and Apache-2.0 are considered incompatible by the FSF.
So this commit replaces the previous wordlist with
a new one:
- weather (basic english weather adjectives)
- colors (basic english color names)
- worlds (planets, moons, minor bodies of the solar system)
All common vocabulary and compiled for this project, not taken
from anywhere.
An example with the new list:
- wintry-rust-dione-9393
- warm-yellow-saturn-39f9
The "worlds" are picked on the following principles:
- well-known
- memorable
- short(ish)
- cool
This is why e.g. we have "thetis" (an astroid) instead of
"tethys" (a moon): easier to spell and more well known.
[1] https://github.com/systemd/systemd/pull/42566
Use the new copy timestamp clamping mechanism from the previous commit
to fix unreproducible wall-clock files in the generated images.
That covers both modes: online mode writes through the kernel, and
offline mode stages the tree in a temporary directory before handing it
to mkfs or mcopy. `mcopy -m` then carries the clamped mtimes into the
FAT.
This complements commit 34c3d57474 (directory times) and commit
f191ca982c (FAT insertion order).
Cover all combinations (online/offline, with and without epoch) in the
new `testcase_vfat_reproducibility()`. Update `testcase_make_symlinks()`
to cover the symlink creation/re-fix their parent directory code paths.
Sadly, images are still not reproducible byte for byte. Document
systemd-repart's $SOURCE_DATE_EPOCH handling and remaining
reproducibility issues in the manpage.
When a partition is deleted from a table containing multiple partitions
of the same type, filling the resulting partition-number gap can place
a new partition before an existing partition matched to an earlier
definition. This changes definition matching on the next invocation and
breaks idempotency.
Keep new partitions after existing partitions of the same type. If no
partition table slot is available after them, fall back to the first
unused slot.
Which existing partition is matched to which definition is still
determined by partition type and partition number order, as documented,
and is unchanged by this.
Fixes#43449
When an administrator installed a custom keyring under /etc,
signature verification selected it instead of the vendor keyring
under /usr. That could make vendor-signed system updates stop
verifying after adding local keys.
Collect all readable default keyrings, including the current and
legacy /etc paths, and pass temporary copies to GnuPG with
separate --keyring options. Keep SYSTEMD_OPENPGP_KEYRING as an
explicit override, add regression coverage for keyring
coexistence, override behavior, and current-path signing, and
silence the expected shellcheck false positive in the test
cleanup helper.
Closes: #40702
Image builds create a key separate from the SecureBoot one for verity
signing. Its certificate ships inside the image as the sysext trust
anchor.
`genkey` certs had a hardcoded "SecureBoot signing key on host <fqdn of
the build machine>" CN, which describes neither that verity role nor a
meaningful hostname.
Make that name configurable with `SecureBootCertificateCommonName=`,
like mkosi's `--genkey-common-name`. That allows image build tools to
re-use `ukify genkey` for non-SB keys.
Unlike the implicit truncation for the default name, a specified one
which is too long is an error. Add a citation where that limit comes
frm.
This adds FONT_SCALE= setting in vconsole.conf,
vconsole.font_scale= kernel command line option and credential support.
When 2 or 200% is specified, the console font size will be doubled.
Closes#43273.
Create the file with open_tmpfile_linkable_at().
Write the recovery key and trailing newline to the temporary fd.
Set the final mode to 0600 before publishing it.
Link it into place with link_tmpfile_at(..., LINK_TMPFILE_SYNC).
`STOPPING=1` is final, explain in the sd_notify man page that this is
the case and log an error if a service attempts to get back out of
STOPPING with another notification.
Fixes#43465 / 98734ac74d
nsresourced hands out transient, recyclable UID/GID ranges to
unprivileged user namespaces, and a BPF-LSM policy is what keeps a
client from leaving inodes owned by its transient range on a file system
that outlives the namespace, so that a later client which gets the same
range can't inherit them.
The old policy decided based on the mount a write went through, which is
forgeable: unshare(CLONE_NEWNS) gives you clones of every mount with
fresh mount IDs but the same superblock, and the mount namespace's owner
is yours to pick. overlayfs sidesteps it entirely. So this reworks the
check to look at where the write actually lands on disk.
The first commit (Christian Brauner's) replaces the per-mount allowlist
with two questions answered from fields the client can't forge and that
survive mount cloning: does the file system die together with the user
namespace (sb->s_user_ns at or below the managed one), and does the
transient ID actually reach the disk, or does an idmapped mount
translate it into something else first. It walks the userns chain
upwards so a nested namespace can't escape it. The map layout changed,
so the pins move to userns-restrict.v2 and the old ones are removed on
install.
The second commit handles overlayfs. A write through an overlay creates
the file on the upper layer via vfs_create(), which only trips the inode
LSM hooks, not the path hooks we attach to, and the one path hook that
does fire sees the overlay mount, which belongs to the managed namespace
and so looks like it dies with it even though the upper may be
persistent. So we judge the upper at mount time in sb_kern_mount and
refuse a writable overlay unless its upper dies with the namespace too.
Reading overlayfs' private ovl_fs/ovl_layer uses CO-RE type flavors
guarded by bpf_core_type_exists(), and the service now orders after
modprobe@overlay.service.
The third commit deals with restarts. The managed set only lives in the
pinned maps, so an upgrade that changes the map layout comes up with
empty maps and every already-running namespace silently loses its
restriction. manager_startup() now re-adds the live registry entries to
the maps in the same pass that reaps the dead ones. The setgroups()
denial is restored from a flag we now store in the registry.
One consequence: a managed namespace can only mount a writable overlay
whose upper dies with it, e.g. a tmpfs it set up itself. If you need a
writable persistent upperdir (mkosi does), use a plain unprivileged user
namespace for that, not a transient nsresourced range.
UnsetEnvironment= was applied to the environment block before the
command line was expanded. Since the expansion looks the variables up
in that same block, any variable listed in UnsetEnvironment= was
already gone when $VAR in ExecStart= and friends was expanded, and a
whole-word $VAR reference was dropped from the command line.
Let the expansion see the full environment block, and apply the
unsetting only to the environment block passed to the executed
process. This way UnsetEnvironment= can hide variables from the
executed process without breaking command lines that reference them.
Extend the exec-unsetenvironment test accordingly: the whole-word
$VAR6 argument must be expanded into a positional parameter for the
shell, while ${VAR6-X} must evaluate to X in the executed process.
Also document in both the UnsetEnvironment= description and the
"Environment Variables in Spawned Processes" section that the
unsetting happens after command line variable expansion.
Fixes: #43343
This adds an initial TPM2 implementation of the io.systemd.Report.Signer
interface, which returns a set of signed TPM attestations that also
includes the supplied report digest.
The returned report consists of multiple components:
- A signed PCR quote generated with TPM2_Quote.
- Signed NvPCR attestations generated with TPM2_NV_Certify.
- A signed audit session attestation generated with
TPM2_GetSessionAuditDigest.
Each signed report component includes the JSON encoded TPMS_ATTEST
attestation structure and corresponding signature, in both PEM encoded
form and as a JSON encoded TPMT_SIGNATURE structure.
NvPCR report components also include the readable name of the NvPCR, the
NV index public area as the JSON encoded TPMS_NV_PUBLIC structure, and some
additional authenticated data that is digested and supplied as the
qualifying data to the TPM2_NV_Certify command. This authenticated data
includes the NvPCR name and priority.
The report digest that is supplied via varlink is supplied as the
qualifying data to the audit session attestation.
The returned report also includes the event log which is retrieved from
pcrlock's varlink interface, and the public area of the signing key in
both PEM encoded form and as a JSON encoded TPMT_PUBLIC structure.
The audit session attestation is always the last component. The
preceding components are all executed with the audit session, and the
signer requires the audit session to remain exclusive whilst generating
the report. What this does is provide evidence to a verifier that the
overall report is a single, consistent snapshot of the system (ie, no
other TPM commands executed whilst generating the report) because the
audit session attestation contains a field that indicates that the
session was exclusive at the time it was attested.
The set of attested PCRs and NvPCRs are currently hardcoded. It includes
all firmware PCRs with the exception of PCR6, and all other PCRs with
the exception of the IMA one (which isn't useful on its own without the
IMA log). All defined NvPCRs are included.
A verifier can verify the signed attestation components individually by
verifying their signatures against the supplied attestation data, using
the supplied public key.
For the PCR report component, a verifier can replay the measurements in
the log in order to reconstruct the PCR values, and then use this and
the PCR selection from the attestation in order to calculate the PCR
digest, and then check that this matches the one in the attestation.
For the NvPCR report components, a verifier checks that the NV index
name in the attestation matches one that is anchored in PCR9 to be sure
that the attestation is for a valid NvPCR. A verifier can then replay
the measurements in the log to ensure that the resulting NvPCR value
matches the one supplied in the attestation. The authenticated data is a
JSON blob containing the NvPCR name and priority. A verifier can digest
this and ensure it matches the qualifying data in the attestation.
The audit session attestation includes the audit session digest and
whether the audit session was still exclusive when the attestation was
generated. A verifier should confirm exclusivity. The digest includes a
record of all TPM commands executed with the audit session, as each
command results in it being extended with the command parameter hash and
the result parameter hash. A verifier should replay the preceding report
components to compute an expected audit digest and make sure that this
digest matches the one in the attestation in order to be sure that the
overall report represents a single, consistent snapshot. The other
report components provide sufficient information for a verifier to
reconstruct the cpHash and rpHash.
When reconstructing the cpHash for the PCR and NvPCR components, the
signing scheme is the NULL scheme (they use the attestation key's
signing scheme). The required signing key public area is supplied in
the report. The supplied qualifying data is in the extra data field of
the attestation.
The PCR selection is also required to reconstruct the cpHash for the
PCR component. The PCR selection is available in the attestation.
The name of the NV index is also required to reconstruct the cpHash for
the NvPCR components. The name is available in the attestation.
The rpHash for each component can be reconstructed from the supplied
attestation blob and signature.
In the future, we might want to add more report component types. Eg, we
could add report components for ordinary NV indexes. Using the audit
session means that we could also add additional components that the TPM
can't attest directly, such as the values of interesting TPM properties
(as the TPM2_GetCapability calls will appear in the audit session digest).
The attestation signing key is stored as a JSON file in the report
signer's state directory. Different types of keys are supported:
- Ordinary keys that are protected by an existing persistent TPM key
such as the SRK or EK.
- Persistent TPM keys.
- Primary keys, which are recreated using a template on use.
When an ordinary or primary key is used, the report signer saves the
object context in its runtime directory. This context is used on future
invocations. This has the benefit that where a primary key is used, it
doesn't need to be recreated on each use. When an ordinary key is used,
we don't need to run TPM2_Load, which requires authorization with the
parent key, on each This authorization currently requires a policy
session for low-range EKs.
Regardless of the key type, it must be a restricted signing key. If no
key exists, an ordinary key is generated automatically.
The attestation key can also have an associated credential which is
attached to the signed report. The credential can be issued by a CA or
some other party during onboarding, and is presented to a verifier as
proof that the attestation key is authentic. It is considered an opaque
blob in order to not require it to be a specific format, such as a X.509
certificate. I've called this a "voucher" though because "cred" or
"credential" has other meanings in systemd.
As a follow-up to this, I plan to add a varlink interface for creating
attestation keys that can be used for report signing.
Since run0 --help now goes through the pager, provide a way to turn that
off from the command line, like all other commands that page --help. The
option is documented the same way as for systemd-run.
parse_argv() requires at least one DEVICE unless --all is given, and
refuses DEVICE arguments when --all is given, so "[DEVICE…]" described
neither mode correctly. Spell out the three modes as separate synopsis
lines, like pcrextend and inhibit do, and update the man page to match.
The custom help() is replaced by a COMMAND() description, and
--introspect-cli is added. The positional argument is spelled MOUNTPOINT
in the synopsis, like the other metavars, instead of /path/to/mountpoint,
and the man page synopsis, which said "[DEVICE]", is fixed to match: the
argument is required and it is a mount point.
The custom help() is replaced by a COMMAND() description, and
--introspect-cli is added. The positional argument is spelled MOUNTPOINT
in the synopsis, like the other metavars, instead of /path/to/mountpoint.
The man page is adjusted to match.
The custom help() is replaced by a COMMAND() description, and
--introspect-cli is added. The synopsis is updated to be more truthful
and consistent between the prog and man page.
The custom help() is replaced by a COMMAND() description, and
--introspect-cli is added. --help now goes through the pager, like other
commands with --no-pager.
Synopses are adjusted. --user-unit/--unit without any unit names is
technically allowed, but not very meaningful, since it's the same as
the default mode. So [] is dropped. And the prog help string is then
adjusted to match the man page.
The securebits parsing code now recognizes 'no-cap-ambient-raise'
(added in Linux 4.3), 'exec-restrict-file', and 'exec-deny-interactive'
(both added in Linux 6.14). The '-locked' variants were added too.
The resolvconf compatibility parser ignored errors from
nameserver, domain, and search lines. If one of those lines was
malformed, resolvectl could still send the partially parsed
configuration to resolved and overwrite the previous link state.
Reproducer:
IF=enp1s0
TMP="$(mktemp -d)"
ln -s "$(command -v resolvectl)" "$TMP/resolvconf"
sudo resolvectl dns "$IF" 1.1.1.1
sudo resolvectl domain "$IF" keep.example
resolvectl domain "$IF"
printf 'nameserver 1.1.1.1\nsearch "unterminated\n' |
sudo "$TMP/resolvconf" -a "$IF" || true
resolvectl domain "$IF"
Before:
The malformed search line was ignored and the previous domain
was cleared:
Link 2 (enp1s0): keep.example
Link 2 (enp1s0):
After:
The malformed input fails before updating resolved, so
keep.example remains configured.
Follow-up for: 097f130731
--raw only affects ResolveRecord output. Without --type= or an
RFC4501 dns: URI, query takes the ResolveHostname/ResolveAddress
paths, where --raw was silently ignored.
Reproducer:
build/resolvectl --raw query localhost
Before:
The command exited successfully and printed regular text output,
such as:
localhost: 127.0.0.1
After:
The command fails before issuing a lookup:
--raw may only be combined with --type= or dns: URIs.
Follow-up for: 05ea7e87b6
A write through an overlay mount does not create the object on the overlay
itself: overlayfs creates it on the upper layer via vfs_create(), which
reaches only the *inode* LSM hooks, not the *path* hooks the transient
range policy attaches to. The one path hook that does fire sees the overlay
mount, whose superblock belongs to the (managed) mounting namespace and so
looks like it dies with it -- while the upper may be a persistent file
system on which the transient IDs then persist.
Regular file system -- caught by the path hook:
openat(dir_on_persistent_fs, "f", O_CREAT)
path_openat -> ... -> security_path_mknod(path{mnt = persistent mount}) << path hook (attached)
userns_restrict_path_mknod -> validate_mount()
sb->s_user_ns = init -> not below managed (outlives the ns)
mnt_idmap does not remap the transient id (reaches disk)
=> -EPERM BLOCKED
Overlay write -- slips past the path hook (this is the hole):
openat(overlay_mnt/"f", O_CREAT)
path_openat -> ... -> security_path_mknod(path{mnt = OVERLAY mount}) << path hook (attached)
validate_mount(): overlay sb->s_user_ns == managed
=> "dies with the namespace" ALLOW
ovl_create_or_link -> vfs_create(UPPER dentry)
security_inode_create(UPPER inode) << inode hook (NOT attached)
=> no check
inode created on the UPPER fs, owned by the transient uid PERSISTS
Judge the upper at mount time instead, in lsm/sb_kern_mount:
mount("overlay", ..., upperdir=<X>, workdir=<Y>)
do_new_mount -> vfs_get_tree
ovl_fill_super
stamps work/index onto the upper via vfs_mkdir, owned by the
transient mounter -> security_inode_mkdir only (not a path hook)
security_sb_kern_mount(sb) << hook (attached)
userns_restrict_sb_kern_mount:
sb->s_magic != OVERLAYFS_SUPER_MAGIC -> return 0 (not an overlay)
find_managed_userns(sb->s_user_ns) == none -> return 0 (unmanaged mounter)
upper = ((struct ovl_fs*)sb->s_fs_info)->layers[0].mnt
upper == NULL -> return 0 (read-only, no upper)
fs_userns = upper->mnt_sb->s_user_ns
upper dies with the managed ns (e.g. a tmpfs) => return 0 ALLOW
upper persistent, idmap records no transient id => return 0 ALLOW
upper persistent, an idmap extent records a transient => -EPERM REFUSE
The upper has to be judged at mount time because overlayfs performs the
actual upper creations (both the mount-time work/index dirs and every later
copy-up) with internal vfs_create()/vfs_mkdir() calls that reach only the
inode hooks, on the upper's own superblock, where neither the overlay's
ovl_fs nor the mount idmapping is available. Refusing the mount stops every
such write. It cannot undo the work/index dirs ovl_fill_super() already
stamped onto the upper before this hook runs. Reaching those takes an
upperdir and a workdir that already exist on the same persistent,
non-idmapped file system and that the transient IDs may write to: the client
cannot create them itself, since that is what the path hooks deny.
The idmap check walks the upper mount's uid_map and gid_map and permits the
overlay only when no extent records a transient id on disk (ids the idmap
does not map fail the write, so they are fine too). This is what lets a
client back a writable overlay with a persistent but id-mapped upper, e.g.
one handed out by mountfsd, while a plain persistent upper stays refused.
The check keys on whether a writable upper exists (layers[0].mnt is
non-NULL), which is fixed for the superblock's lifetime, not on the mutable
SB_RDONLY flag: an overlay mounted read-only but with an upper can be
remounted read-write later without re-entering sb_kern_mount (remount uses a
different LSM hook), so it must be judged now. A genuinely read-only overlay
has no upper and is left alone. Reading the upper layer needs overlayfs'
private struct ovl_fs/ovl_layer, which are absent from vmlinux.h when
overlayfs is built as a module; they are declared as CO-RE type flavors and
guarded by bpf_core_type_exists(), and the service now orders itself after
modprobe@overlay.service so the module's BTF is present by the time the
program is loaded.
A managed (nsresourced-provisioned) user namespace can therefore only mount
a writable overlay whose upper dies with it (e.g. a tmpfs it set up
itself). Callers that need a writable, persistent (non-tmpfs) upperdir --
mkosi, for one -- should use a regular unprivileged user namespace for that
rather than a transient nsresourced range, since such an overlay is refused
for a managed namespace by design.
test-userns-restrict now mounts real overlays: a read-only overlay, a
writable overlay with a tmpfs upper, and a writable overlay whose upper is
an init-owned but idmapped mount are all allowed, while a writable overlay
with a plain init-owned upper is refused with EPERM. The kernel permits that
last mount without the LSM loaded, so the EPERM is the policy's doing.
nsresourced hands out transient, recyclable UID/GID ranges to
unprivileged user namespaces. So that a client cannot gain persistence by
leaving inodes owned by its transient range on a file system that outlives
the namespace -- where a later, unrelated client that recycles the range
would inherit them -- a BPF-LSM policy vetoes inode creation and chown()
that would end up owned by a transient ID.
The policy this replaces keyed its decision on properties of the mount a
write targeted. Those can be forged: a single unshare(CLONE_NEWNS) hands
the namespace clones of every mount it can see, each backed by the very
same superblock but no longer recognisable by the original check, and the
mount namespace's owning user namespace is attacker-chosen as well.
Decide instead from two questions about the object the write would actually
create, both answered from fields the kernel stamps itself and that survive
mount cloning and cannot be forged with unshare():
a) Does the file system die with the user namespace? A superblock records
the user namespace it was mounted in (sb->s_user_ns); if that sits at
or below the managed namespace, nothing it carries can outlive the
transient range.
b) Will the transient ID actually reach the disk? An idmapped mount
(vfsmount->mnt_idmap) may translate it into something else first, in
which case nothing recyclable is recorded. This mirrors the kernel's
own from_vfsuid()/from_vfsgid().
Walking the user-namespace chain upwards, rather than looking only at the
exact namespace, is what keeps a nested namespace from shaking off the
policy.
The map schema changed incompatibly (the old mount-id allowlist became the
flat userns_managed inode set), so the BPF objects are pinned under a fresh
directory, /sys/fs/bpf/systemd/userns-restrict-v2, and the obsolete
unsuffixed tree from previous versions is removed on install. Removing the
old link pins detaches the previous, bypassable programs, so they do not
linger attached next to the new ones.