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78 lines
3.7 KiB
78 lines
3.7 KiB
8 months ago
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From 8d11c92de8644e5f090018933bad25be0f2adebb Mon Sep 17 00:00:00 2001
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From: Luca Boccassi <bluca@debian.org>
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Date: Wed, 8 Feb 2023 00:25:00 +0000
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Subject: [PATCH] core: imply DeviceAllow=/dev/tpmrm0 with
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LoadCredentialEncrypted
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If the device access policy is restricted, add implicitly access to the TPM
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if at least one encrypted credential needs to be loaded.
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Fixes https://github.com/systemd/systemd/issues/26042
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(cherry picked from commit 398dc7d39b9a877e71529f0e0b139329e4c6992e)
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Related: RHEL-16182
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---
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man/systemd.exec.xml | 8 +++++++-
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src/core/unit.c | 10 ++++++++++
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test/units/testsuite-70.sh | 6 ++++++
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3 files changed, 23 insertions(+), 1 deletion(-)
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diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
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index 29666b102b..4927764b9b 100644
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--- a/man/systemd.exec.xml
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+++ b/man/systemd.exec.xml
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@@ -3113,7 +3113,13 @@ StandardInputData=V2XigLJyZSBubyBzdHJhbmdlcnMgdG8gbG92ZQpZb3Uga25vdyB0aGUgcnVsZX
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authenticated credentials improves security as credentials are not stored in plaintext and only
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authenticated and decrypted into plaintext the moment a service requiring them is started. Moreover,
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credentials may be bound to the local hardware and installations, so that they cannot easily be
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- analyzed offline, or be generated externally.</para>
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+ analyzed offline, or be generated externally. When <varname>DevicePolicy=</varname> is set to
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+ <literal>closed</literal> or <literal>strict</literal>, or set to <literal>auto</literal> and
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+ <varname>DeviceAllow=</varname> is set, or <varname>PrivateDevices=</varname> is set, then this
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+ setting adds <filename>/dev/tpmrm0</filename> with <constant>rw</constant> mode to
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+ <varname>DeviceAllow=</varname>. See
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+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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+ for the details about <varname>DevicePolicy=</varname> or <varname>DeviceAllow=</varname>.</para>
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<para>The credential files/IPC sockets must be accessible to the service manager, but don't have to
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be directly accessible to the unit's processes: the credential data is read and copied into separate,
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diff --git a/src/core/unit.c b/src/core/unit.c
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index c9a42ee3d7..f109d16eb3 100644
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--- a/src/core/unit.c
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+++ b/src/core/unit.c
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@@ -4191,6 +4191,16 @@ int unit_patch_contexts(Unit *u) {
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if (r < 0)
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return r;
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}
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+
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+ /* If there are encrypted credentials we might need to access the TPM. */
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+ ExecLoadCredential *cred;
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+ HASHMAP_FOREACH(cred, ec->load_credentials)
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+ if (cred->encrypted) {
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+ r = cgroup_add_device_allow(cc, "/dev/tpmrm0", "rw");
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+ if (r < 0)
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+ return r;
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+ break;
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+ }
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}
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}
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diff --git a/test/units/testsuite-70.sh b/test/units/testsuite-70.sh
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index 3b4d66b686..2c405bccbb 100755
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--- a/test/units/testsuite-70.sh
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+++ b/test/units/testsuite-70.sh
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@@ -185,6 +185,12 @@ else
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echo "/usr/lib/systemd/systemd-pcrphase or PCR sysfs files not found, skipping PCR extension test case"
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fi
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+# Ensure that sandboxing doesn't stop creds from being accessible
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+echo "test" > /tmp/testdata
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+systemd-creds encrypt /tmp/testdata /tmp/testdata.encrypted --with-key=tpm2
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+systemd-run -p PrivateDevices=yes -p LoadCredentialEncrypted=testdata.encrypted:/tmp/testdata.encrypted --pipe --wait systemd-creds cat testdata.encrypted | cmp - /tmp/testdata
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+rm /tmp/testdata
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+
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echo OK >/testok
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exit 0
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