If it is null, we get the 'base' param unchanged:
$ build/systemd-id128 show 00000000000000000000000000000001 \
--app-specific=00000000000000000000000000000000
00000000000000000000000000000001
This is not good, because it breaks our promise that the base (usually either
machine-id or boot-id) cannot be derived from the result. Some application
using the library could use a null app id, inadvertently exposing the machine
or boot id. (This could happen because of forgotten initialization, or maybe
because the app id is configurable, and the user configures it wrongly.)
Note: the other way the secret is not exposed:
$ build/systemd-id128 show 00000000000000000000000000000000 \
--app-specific=00000000000000000000000000000002
4f63080959264900b0d88d999dae2d3a
Normally systemd would not allow a null machine-id or boot-id, but we can let
the user do the calculation that if they want to.
This tries to add information about when each option was added. It goes
back to version 183.
The version info is included from a separate file to allow generating it,
which would allow more control on the formatting of the final output.
EINVAL suggests that the caller passes an invalid argument. EIO is
for "input/output error", i.e. the error you'd get if the disk or
file system is borked, and this error code could be returned by the
underlying read/write functions.
Let's make the functions return an unambiguous error code.
And drop to mention sd_id128_get_boot_app_specific() may return -ENOENT
or -ENOMEDIUM. The function does not read /etc/machine-id. But reads a
file in the procfs, which is a kind of the kernel API. Hence the
failures are caused only when the system has wrong setup.
So in theory UUID Variant 2 (i.e. microsoft GUIDs) are supposed to be
displayed in native endian. That is of course a bad idea, and Linux
userspace generally didn't implement that, i.e. uuidd and similar.
Hence, let's not bother either, but let's document that we treat
everything the same as Variant 1, even if it declares something else.
This is the case because the ID128 we generate are all marked as v4 UUID
which requires that some bits are zero and others are one. Let's
document this so that people can rely on SD_ID128_NULL being a special
value for "uninitialized" that is always distinguishable from generated
UUIDs.
The "include" files had type "book" for some raeason. I don't think this
is meaningful. Let's just use the same everywhere.
$ perl -i -0pe 's^..DOCTYPE (book|refentry) PUBLIC "-//OASIS//DTD DocBook XML V4.[25]//EN"\s+"http^<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"\n "http^gms' man/*.xml
No need to waste space, and uniformity is good.
$ perl -i -0pe 's|\n+<!--\s*SPDX-License-Identifier: LGPL-2.1..\s*-->|\n<!-- SPDX-License-Identifier: LGPL-2.1+ -->|gms' man/*.xml
The raison d'etre for this program is printing machine-app-specific IDs. We
provide a library function for that, but not a convenient API. We can hardly
ask people to quickly hack their own C programs or call libsystemd through CFFI
in python or another scripting language if they just want to print an ID.
Verb 'new' was already available as 'journalctl --new-id128', but this makes
it more discoverable.
v2:
- rename binary to systemd-id128
- make --app-specific= into a switch that applies to boot-id and machine-id
Moving them out makes it easier to run them through a compiler, use automatic
indentation, and opens the possibility to provide a download link in the
future. I verified that all examples compile cleanly.
(2-space indentation is used because the examples are already significantly
indented in the man page, and we need to keep them narrow so that they display
well on standard terminals.)
Docbook styles required those to be present, even though the templates that we
use did not show those names anywhere. But something changed semi-recently (I
would suspect docbook templates, but there was only a minor version bump in
recent years, and the changelog does not suggest anything related), and builds
now work without those entries. Let's drop this dead weight.
Tested with F26-F29, debian unstable.
$ perl -i -0pe 's/\s*<authorgroup>.*<.authorgroup>//gms' man/*xml
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
The only difference is that functions are not individually listed by name,
but that seems completely pointless, since all functions that are documented
are always exported, so the generic text tells the user all she or he needs
to know.
We currently return -ENOMEDIUM when /etc/machine-id is empty, and -EINVAL when
it is all zeros. But -EINVAL is also used for invalid args. The distinction
between empty and all-zero is not very important, let's use the same return
code.
Also document -ENOENT and -ENOMEDIUM since they can be a bit surprising.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
This adds an API for retrieving an app-specific machine ID to sd-id128.
Internally it calculates HMAC-SHA256 with an 128bit app-specific ID as payload
and the machine ID as key.
(An alternative would have been to use siphash for this, which is also
cryptographically strong. However, as it only generates 64bit hashes it's not
an obvious choice for generating 128bit IDs.)
Fixes: #4667
This adds a new invocation ID concept to the service manager. The invocation ID
identifies each runtime cycle of a unit uniquely. A new randomized 128bit ID is
generated each time a unit moves from and inactive to an activating or active
state.
The primary usecase for this concept is to connect the runtime data PID 1
maintains about a service with the offline data the journal stores about it.
Previously we'd use the unit name plus start/stop times, which however is
highly racy since the journal will generally process log data after the service
already ended.
The "invocation ID" kinda matches the "boot ID" concept of the Linux kernel,
except that it applies to an individual unit instead of the whole system.
The invocation ID is passed to the activated processes as environment variable.
It is additionally stored as extended attribute on the cgroup of the unit. The
latter is used by journald to automatically retrieve it for each log logged
message and attach it to the log entry. The environment variable is very easily
accessible, even for unprivileged services. OTOH the extended attribute is only
accessible to privileged processes (this is because cgroupfs only supports the
"trusted." xattr namespace, not "user."). The environment variable may be
altered by services, the extended attribute may not be, hence is the better
choice for the journal.
Note that reading the invocation ID off the extended attribute from journald is
racy, similar to the way reading the unit name for a logging process is.
This patch adds APIs to read the invocation ID to sd-id128:
sd_id128_get_invocation() may be used in a similar fashion to
sd_id128_get_boot().
PID1's own logging is updated to always include the invocation ID when it logs
information about a unit.
A new bus call GetUnitByInvocationID() is added that allows retrieving a bus
path to a unit by its invocation ID. The bus path is built using the invocation
ID, thus providing a path for referring to a unit that is valid only for the
current runtime cycleof it.
Outlook for the future: should the kernel eventually allow passing of cgroup
information along AF_UNIX/SOCK_DGRAM messages via a unique cgroup id, then we
can alter the invocation ID to be generated as hash from that rather than
entirely randomly. This way we can derive the invocation race-freely from the
messages.
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.
* by adjusting the path to binaries, but not do the same thing to the
search path we end up with inconsistent man-pages. Adjusting the search
path too would be quite messy, and it is not at all obvious that this is
worth the effort, but at any rate it would have to be done before we
could ship this.
* this means that distributed man-pages does not make sense as they depend
on config options, and for better or worse we are still distributing
man pages, so that is something that definitely needs sorting out before
we could ship with this patch.
* we have long held that split-usr is only minimally supported in order
to boot, and something we hope will eventually go away. So before we start
adding even more magic/effort in order to make this work nicely, we should
probably question if it makes sense at all.
In particular, use /lib/systemd instead of /usr/lib/systemd in distributions
like Debian which still have not adopted a /usr merge setup.
Use XML entities from man/custom-entities.ent to replace configured paths while
doing XSLT processing of the original XML files. There was precedent of some
files (such as systemd.generator.xml) which were already using this approach.
This addresses most of the (manual) fixes from this patch:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220
The idea of using generic XML entities was presented here:
http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html
This patch solves almost all the issues, with the exception of:
- Path to /bin/mount and /bin/umount.
- Generic statements about preference of /lib over /etc.
These will be handled separately by follow up patches.
Tested:
- With default configure settings, ran "make install" to two separate
directories and compared the output to confirm they matched exactly.
- Used a set of configure flags including $CONFFLAGS from Debian:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules
Installed the tree and confirmed the paths use /lib/systemd instead of
/usr/lib/systemd and that no other unexpected differences exist.
- Confirmed that `make distcheck` still passes.
It is annoying when we have dead links on fd.o.
Add project='man-pages|die-net|archlinux' to <citerefentry>-ies.
In generated html, add external links to
http://man7.org/linux/man-pages/man, http://linux.die.net/man/,
https://www.archlinux.org/.
By default, pages in sections 2 and 4 go to man7, since Michael
Kerrisk is the autorative source on kernel related stuff.
The rest of links goes to linux.die.net, because they have the
manpages.
Except for the pacman stuff, since it seems to be only available from
archlinux.org.
Poor gummiboot gets no link, because gummitboot(8) ain't to be found
on the net. According to common wisdom, that would mean that it does
not exist. But I have seen Kay using it, so I know it does, and
deserves to be found. Can somebody be nice and put it up somewhere?
Shift the asterisks in the documentation's prototypes such that they
are consistent among each other. Use the right side to match what is
used in source code.
Addendum to commit v209~82.
Use proper grammar, word usage, adjective hyphenation, commas,
capitalization, spelling, etc.
To improve readability, some run-on sentences or sentence fragments were
revised.
[zj: remove the space from 'file name', 'host name', and 'time zone'.]
Before: libsystemd-daemonpkg-config(1)
After: libsystemd-daemon pkg-config(1)
This fix is more complicated than it should be due to the consecutive
XML elements separated by collapsible whitespace.
Merging the lines and separating the XML elements with an en space or a
non-breaking space is the only solution that results in one, and only
one, space being inserted between them when testing. An em space results
in two spaces being inserted.
