sysext: introduce ARCHITECTURE field to match host architecture

When an extension image has binaries they should match the host
architecture. Currently there is no way to specify this requirement.
Introduce an ARCHITECTURE field in the extension's release file that
may be set to prevent loading on the wrong host architecture.
Since this new field is introduced late, we don't want to make
specifying it mandatory as it would break existing sysext images.

See https://github.com/systemd/systemd/issues/24061
This commit is contained in:
Kai Lueke 2022-08-09 17:07:20 +02:00
parent ab4d43c54e
commit 16c1ca0db4
4 changed files with 34 additions and 6 deletions

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@ -411,6 +411,18 @@
determines the fallback hostname.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>ARCHITECTURE=</varname></term>
<listitem><para>A string that specifies which CPU architecture the userspace binaries require.
The architecture identifiers are the same as for <varname>ConditionArchitecture=</varname>
described in <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
The field is optional and should only be used when just single architecture is supported.
It may provide redundant information when used in a GPT partition with a GUID type that already
encodes the architecture. If this is not the case, the architecture should be specified in
e.g., an extension image, to prevent an incompatible host from loading it.
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SYSEXT_LEVEL=</varname></term>

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@ -118,10 +118,14 @@
file: the contained <varname>ID=</varname> fields have to match unless <literal>_any</literal> is set
for the extension. If the extension <varname>ID=</varname> is not <literal>_any</literal>, the
<varname>SYSEXT_LEVEL=</varname> field (if defined) has to match. If the latter is not defined, the
<varname>VERSION_ID=</varname> field has to match instead. System extensions should not ship a
<filename>/usr/lib/os-release</filename> file (as that would be merged into the host
<filename>/usr/</filename> tree, overriding the host OS version data, which is not desirable). The
<filename>extension-release</filename> file follows the same format and semantics, and carries the same
<varname>VERSION_ID=</varname> field has to match instead. If the extension defines the
<varname>ARCHITECTURE=</varname> field and the value is not <literal>_any</literal> it has to match the kernel's
architecture reported by <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
but the used architecture identifiers are the same as for <varname>ConditionArchitecture=</varname>
described in <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
System extensions should not ship a <filename>/usr/lib/os-release</filename> file (as that would be merged
into the host <filename>/usr/</filename> tree, overriding the host OS version data, which is not desirable).
The <filename>extension-release</filename> file follows the same format and semantics, and carries the same
content, as the <filename>os-release</filename> file of the OS, but it describes the resources carried
in the extension image.</para>
</refsect1>

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@ -1,6 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "alloc-util.h"
#include "architecture.h"
#include "env-util.h"
#include "extension-release.h"
#include "log.h"
@ -15,7 +16,7 @@ int extension_release_validate(
const char *host_sysext_scope,
char **extension_release) {
const char *extension_release_id = NULL, *extension_release_sysext_level = NULL;
const char *extension_release_id = NULL, *extension_release_sysext_level = NULL, *extension_architecture = NULL;
assert(name);
assert(!isempty(host_os_release_id));
@ -48,6 +49,16 @@ int extension_release_validate(
}
}
/* When the architecture field is present and not '_any' it must match the host - for now just look at uname but in
* the future we could check if the kernel also supports 32 bit or binfmt has a translator set up for the architecture */
extension_architecture = strv_env_pairs_get(extension_release, "ARCHITECTURE");
if (!isempty(extension_architecture) && !streq(extension_architecture, "_any") &&
!streq(architecture_to_string(uname_architecture()), extension_architecture)) {
log_debug("Extension '%s' is for architecture '%s', but deployed on top of '%s'.",
name, extension_architecture, architecture_to_string(uname_architecture()));
return 0;
}
extension_release_id = strv_env_pairs_get(extension_release, "ID");
if (isempty(extension_release_id)) {
log_debug("Extension '%s' does not contain ID in extension-release but requested to match '%s' or be '_any'",

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@ -715,7 +715,8 @@ EOF
export initdir="$TESTDIR/app-nodistro"
mkdir -p "$initdir/usr/lib/extension-release.d" "$initdir/usr/lib/systemd/system"
( echo "ID=_any" ) >"$initdir/usr/lib/extension-release.d/extension-release.app-nodistro"
( echo "ID=_any"
echo "ARCHITECTURE=_any" ) >"$initdir/usr/lib/extension-release.d/extension-release.app-nodistro"
echo MARKER=1 >"$initdir/usr/lib/systemd/system/some_file"
mksquashfs "$initdir" "$oldinitdir/usr/share/app-nodistro.raw" -noappend
)