man/systemd-cryptenroll.xml

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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   4   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
   5 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   6 <refentry id="systemd-cryptenroll" xmlns:xi="http://www.w3.org/2001/XInclude" conditional='HAVE_LIBCRYPTSETUP'>
   7
   8   <refentryinfo>
   9     <title>systemd-cryptenroll</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>systemd-cryptenroll</refentrytitle>
  15     <manvolnum>1</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>systemd-cryptenroll</refname>
  20     <refpurpose>Enroll PKCS#11, FIDO2, TPM2 token/devices to LUKS2 encrypted volumes</refpurpose>
  21   </refnamediv>
  22
  23   <refsynopsisdiv>
  24     <cmdsynopsis>
  25       <command>systemd-cryptenroll</command>
  26       <arg choice="opt" rep="repeat">OPTIONS</arg>
  27       <arg choice="opt">DEVICE</arg>
  28     </cmdsynopsis>
  29   </refsynopsisdiv>
  30
  31   <refsect1>
  32     <title>Description</title>
  33
  34     <para><command>systemd-cryptenroll</command> is a tool for enrolling hardware security tokens and devices
  35     into a LUKS2 encrypted volume, which may then be used to unlock the volume during boot. Specifically, it
  36     supports tokens and credentials of the following kind to be enrolled:</para>
  37
  38     <orderedlist>
  39       <listitem><para>PKCS#11 security tokens and smartcards that may carry an RSA or EC key pair (e.g.
  40       various YubiKeys)</para></listitem>
  41
  42       <listitem><para>FIDO2 security tokens that implement the <literal>hmac-secret</literal> extension (most
  43       FIDO2 keys, including YubiKeys)</para></listitem>
  44
  45       <listitem><para>TPM2 security devices</para></listitem>
  46
  47       <listitem><para>Regular passphrases</para></listitem>
  48
  49       <listitem><para>Recovery keys. These are similar to regular passphrases, however are randomly generated
  50       on the computer and thus generally have higher entropy than user-chosen passphrases. Their character
  51       set has been designed to ensure they are easy to type in, while having high entropy. They may also be
  52       scanned off screen using QR codes. Recovery keys may be used for unlocking LUKS2 volumes wherever
  53       passphrases are accepted. They are intended to be used in combination with an enrolled hardware
  54       security token, as a recovery option when the token is lost.</para></listitem>
  55     </orderedlist>
  56
  57     <para>In addition, the tool may be used to enumerate currently enrolled security tokens and wipe a subset
  58     of them. The latter may be combined with the enrollment operation of a new security token, in order to
  59     update or replace enrollments.</para>
  60
  61     <para>The tool supports only LUKS2 volumes, as it stores token meta-information in the LUKS2 JSON token
  62     area, which is not available in other encryption formats.</para>
  63
  64     <para><command>systemd-cryptsetup</command> operates on the device backing <filename>/var/</filename> if
  65     no device is specified explicitly, and no wipe operation is requested. (Note that in the typical case
  66     where <filename>/var/</filename> is on the same file system as the root file system, this hence enrolls a
  67     key into the backing device of the root file system.)</para>
  68
  69     <refsect2>
  70       <title>TPM2 PCRs and policies</title>
  71
  72       <para>PCRs allow binding of the encryption of secrets to specific software versions and system state,
  73       so that the enrolled key is only accessible (may be "unsealed") if specific trusted software and/or
  74       configuration is used. Such bindings may be created with the option <option>--tpm2-pcrs=</option>
  75       described below.</para>
  76
  77       <para>Secrets may also be bound indirectly: a signed policy for a state of some combination of PCR
  78       values is provided, and the secret is bound to the public part of the key used to sign this policy.
  79       This means that the owner of a key can generate a sequence of signed policies, for specific software
  80       versions and system states, and the secret can be decrypted as long as the machine state matches one of
  81       those policies. For example, a vendor may provide such a policy for each kernel+initrd update, allowing
  82       users to encrypt secrets so that they can be decrypted when running any kernel+initrd signed by the
  83       vendor. Such bindings may be created with the options <option>--tpm2-public-key=</option>,
  84       <option>--tpm2-public-key-pcrs=</option>, <option>--tpm2-signature=</option> described below.
  85       </para>
  86
  87       <para>See <ulink url="https://uapi-group.org/specifications/specs/linux_tpm_pcr_registry/">Linux TPM
  88       PCR Registry</ulink> for an authoritative list of PCRs and how they are updated. The table below
  89       contains a quick reference, describing in particular the PCRs modified by systemd.</para>
  90
  91       <table>
  92         <title>Well-known PCR Definitions</title>
  93
  94         <!-- See: https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/ -->
  95         <!-- See: https://github.com/rhboot/shim/blob/main/README.tpm -->
  96         <!-- See: https://www.gnu.org/software/grub/manual/grub/html_node/Measured-Boot.html -->
  97         <!-- See: https://sourceforge.net/p/linux-ima/wiki/Home/ -->
  98         <!-- See: https://github.com/tianocore-docs/edk2-TrustedBootChain/blob/main/4_Other_Trusted_Boot_Chains.md -->
  99         <!-- See: https://wiki.archlinux.org/title/Trusted_Platform_Module#Accessing_PCR_registers -->
 100
 101         <tgroup cols='3' align='left' colsep='1' rowsep='1'>
 102           <colspec colname="pcr" />
 103           <colspec colname="name" />
 104           <colspec colname="definition" />
 105
 106           <thead>
 107             <row>
 108               <entry>PCR</entry>
 109               <entry>name</entry>
 110               <entry>Explanation</entry>
 111             </row>
 112           </thead>
 113
 114           <tbody>
 115             <row>
 116               <entry>0</entry>
 117               <entry>platform-code</entry>
 118               <entry>Core system firmware executable code; changes on firmware updates</entry>
 119             </row>
 120
 121             <row>
 122               <entry>1</entry>
 123               <entry>platform-config</entry>
 124               <entry>Core system firmware data/host platform configuration; typically contains serial and model numbers, changes on basic hardware/CPU/RAM replacements</entry>
 125             </row>
 126
 127             <row>
 128               <entry>2</entry>
 129               <entry>external-code</entry>
 130               <entry>Extended or pluggable executable code; includes option ROMs on pluggable hardware</entry>
 131             </row>
 132
 133             <row>
 134               <entry>3</entry>
 135               <entry>external-config</entry>
 136               <entry>Extended or pluggable firmware data; includes information about pluggable hardware</entry>
 137             </row>
 138
 139             <row>
 140               <entry>4</entry>
 141               <entry>boot-loader-code</entry>
 142               <entry>Boot loader and additional drivers, PE binaries invoked by the boot loader; changes on boot loader updates. <citerefentry><refentrytitle>sd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> measures system extension images read from the ESP here too (see <citerefentry><refentrytitle>systemd-sysext</refentrytitle><manvolnum>8</manvolnum></citerefentry>).</entry>
 143             </row>
 144
 145             <row>
 146               <entry>5</entry>
 147               <entry>boot-loader-config</entry>
 148               <entry>GPT/Partition table; changes when the partitions are added, modified, or removed</entry>
 149             </row>
 150
 151             <row>
 152               <entry>7</entry>
 153               <entry>secure-boot-policy</entry>
 154               <entry>Secure Boot state; changes when UEFI SecureBoot mode is enabled/disabled, or firmware certificates (PK, KEK, db, dbx, …) changes.</entry>
 155             </row>
 156
 157             <row>
 158               <entry>9</entry>
 159               <entry>kernel-initrd</entry>
 160               <entry>The Linux kernel measures all initrds it receives into this PCR.</entry>
 161               <!-- Strictly speaking only Linux >= 5.17 using the LOAD_FILE2 protocol, see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f046fff8bc4c4d8f8a478022e76e40b818f692df -->
 162             </row>
 163
 164             <row>
 165               <entry>10</entry>
 166               <entry>ima</entry>
 167               <entry>The IMA project measures its runtime state into this PCR.</entry>
 168             </row>
 169
 170             <row>
 171               <entry>11</entry>
 172               <entry>kernel-boot</entry>
 173               <entry><citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> measures the ELF kernel image, embedded initrd and other payload of the PE image it is placed in into this PCR. <citerefentry><refentrytitle>systemd-pcrphase.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> measures boot phase strings into this PCR at various milestones of the boot process.</entry>
 174             </row>
 175
 176             <row>
 177               <entry>12</entry>
 178               <entry>kernel-config</entry>
 179               <entry><citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> measures the kernel command line into this PCR. <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> measures any manually specified kernel command line (i.e. a kernel command line that overrides the one embedded in the unified PE image) and loaded credentials into this PCR.</entry>
 180             </row>
 181
 182             <row>
 183               <entry>13</entry>
 184               <entry>sysexts</entry>
 185               <entry><citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> measures any <citerefentry><refentrytitle>systemd-sysext</refentrytitle><manvolnum>8</manvolnum></citerefentry> images it passes to the booted kernel into this PCR.</entry>
 186             </row>
 187
 188             <row>
 189               <entry>14</entry>
 190               <entry>shim-policy</entry>
 191               <entry>The shim project measures its "MOK" certificates and hashes into this PCR.</entry>
 192             </row>
 193
 194             <row>
 195               <entry>15</entry>
 196               <entry>system-identity</entry>
 197               <entry><citerefentry><refentrytitle>systemd-cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry> optionally measures the volume key of activated LUKS volumes into this PCR. <citerefentry><refentrytitle>systemd-pcrmachine.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> measures the <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> into this PCR. <citerefentry><refentrytitle>systemd-pcrfs@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> measures mount points, file system UUIDs, labels, partition UUIDs of the root and <filename>/var/</filename> filesystems into this PCR.</entry>
 198             </row>
 199
 200             <row>
 201               <entry>16</entry>
 202               <entry>debug</entry>
 203               <entry>Debug</entry>
 204             </row>
 205
 206             <row>
 207               <entry>23</entry>
 208               <entry>application-support</entry>
 209               <entry>Application Support</entry>
 210             </row>
 211           </tbody>
 212         </tgroup>
 213       </table>
 214
 215       <para>In general, encrypted volumes would be bound to some combination of PCRs 7, 11, and 14 (if
 216       shim/MOK is used). In order to allow firmware and OS version updates, it is typically not advisable to
 217       use PCRs such as 0 and 2, since the program code they cover should already be covered indirectly
 218       through the certificates measured into PCR 7. Validation through certificates hashes is typically
 219       preferable over validation through direct measurements as it is less brittle in context of OS/firmware
 220       updates: the measurements will change on every update, but signatures should remain unchanged. See the
 221       <ulink url="https://uapi-group.org/specifications/specs/linux_tpm_pcr_registry/">Linux TPM PCR
 222       Registry</ulink> for more discussion.</para>
 223     </refsect2>
 224   </refsect1>
 225
 226   <refsect1>
 227     <title>Limitations</title>
 228
 229     <para>Note that currently when enrolling a new key of one of the five supported types listed above, it is
 230     required to first provide a passphrase, a recovery key, a FIDO2 token, or a TPM2 key. It's currently not
 231     supported to unlock a device with a PKCS#11 key in order to enroll a new PKCS#11 key. Thus, if in future
 232     key roll-over is desired it's generally recommended to ensure a passphrase, a recovery key, a FIDO2
 233     token, or a TPM2 key is always enrolled.</para>
 234
 235     <para>Also note that support for enrolling multiple FIDO2 tokens is currently limited. When multiple FIDO2
 236     tokens are enrolled, <command>systemd-cryptsetup</command> will perform pre-flight requests to attempt to
 237     identify which of the enrolled tokens are currently plugged in. However, this is not possible for FIDO2
 238     tokens with user verification (UV, usually via biometrics), in which case it will fall back to attempting
 239     each enrolled token one by one. This will result in multiple prompts for PIN and user verification. This
 240     limitation does not apply to PKCS#11 tokens.</para>
 241   </refsect1>
 242
 243   <refsect1>
 244     <title>Compatibility</title>
 245
 246     <para>Security technology both in systemd and in the general industry constantly evolves. In order to
 247     provide best security guarantees, the way TPM2, FIDO2, PKCS#11 devices are enrolled is regularly updated
 248     in newer versions of systemd. Whenever this happens the following compatibility guarantees are given:</para>
 249
 250     <itemizedlist>
 251       <listitem><para>Old enrollments continue to be supported and may be unlocked with newer versions of
 252       <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
 253
 254       <listitem><para>The opposite is not guaranteed however: it might not be possible to unlock volumes with
 255       enrollments done with a newer version of <command>systemd-cryptenroll</command> with an older version
 256       of <command>systemd-cryptsetup</command>.</para></listitem>
 257     </itemizedlist>
 258
 259     <para>That said, it is generally recommended to use matching versions of
 260     <command>systemd-cryptenroll</command> and <command>systemd-cryptsetup</command>, since this is best
 261     tested and supported.</para>
 262
 263     <para>It might be advisable to re-enroll existing enrollments to take benefit of newer security features,
 264     as they are added to systemd.</para>
 265   </refsect1>
 266
 267   <refsect1>
 268     <title>Options</title>
 269
 270     <para>The following options are understood:</para>
 271
 272     <variablelist>
 273       <varlistentry>
 274         <term><option>--password</option></term>
 275
 276         <listitem><para>Enroll a regular password/passphrase. This command is mostly equivalent to
 277         <command>cryptsetup luksAddKey</command>, however may be combined with
 278         <option>--wipe-slot=</option> in one call, see below.</para>
 279
 280         <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 281       </varlistentry>
 282
 283       <varlistentry>
 284         <term><option>--recovery-key</option></term>
 285
 286         <listitem><para>Enroll a recovery key. Recovery keys are mostly identical to passphrases, but are
 287         computer-generated instead of being chosen by a human, and thus have a guaranteed high entropy. The
 288         key uses a character set that is easy to type in, and may be scanned off screen via a QR code.
 289         </para>
 290
 291         <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 292       </varlistentry>
 293
 294       <varlistentry>
 295         <term><option>--unlock-key-file=<replaceable>PATH</replaceable></option></term>
 296
 297         <listitem><para>Use a file instead of a password/passphrase read from stdin to unlock the volume.
 298         Expects the PATH to the file containing your key to unlock the volume. Currently there is nothing like
 299         <option>--key-file-offset=</option> or <option>--key-file-size=</option> so this file has to only
 300         contain the full key.</para>
 301
 302         <xi:include href="version-info.xml" xpointer="v252"/></listitem>
 303       </varlistentry>
 304
 305       <varlistentry>
 306         <term><option>--unlock-fido2-device=<replaceable>PATH</replaceable></option></term>
 307
 308         <listitem><para>Use a FIDO2 device instead of a password/passphrase read from stdin to unlock the
 309         volume. Expects a <filename>hidraw</filename> device referring to the FIDO2 device (e.g.
 310         <filename>/dev/hidraw1</filename>). Alternatively the special value <literal>auto</literal> may be
 311         specified, in order to automatically determine the device node of a currently plugged in security
 312         token (of which there must be exactly one). This automatic discovery is unsupported if
 313         <option>--fido2-device=</option> option is also specified.</para>
 314
 315         <xi:include href="version-info.xml" xpointer="v253"/></listitem>
 316       </varlistentry>
 317
 318       <varlistentry>
 319         <term><option>--unlock-tpm2-device=<replaceable>PATH</replaceable></option></term>
 320
 321         <listitem><para>Use a TPM2 device instead of a password/passhprase read from stdin to unlock the
 322         volume. Expects a device node path referring to the TPM2 chip (e.g. <filename>/dev/tpmrm0</filename>).
 323         Alternatively the special value <literal>auto</literal> may be specified, in order to automatically
 324         determine the device node of a currently discovered TPM2 device (of which there must be exactly one).
 325         </para>
 326
 327         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 328       </varlistentry>
 329
 330       <varlistentry>
 331         <term><option>--pkcs11-token-uri=<replaceable>URI</replaceable></option></term>
 332
 333         <listitem><para>Enroll a PKCS#11 security token or smartcard (e.g. a YubiKey). Expects a PKCS#11 URI
 334         that allows to find an X.509 certificate or a public key on the token. The URI must also be suitable
 335         to find a related private key after changing the type of object in it. Alternatively the special
 336         value <literal>auto</literal> may be specified, in order to automatically determine the suitable URI
 337         if a single security token containing a single key pair is plugged in. The special value
 338         <literal>list</literal> may be used to enumerate all suitable PKCS#11 tokens currently plugged in.
 339         </para>
 340
 341         <para>The PKCS#11 token must contain an RSA or EC key pair which will be used to unlock a LUKS2 volume.
 342         For RSA, a randomly generated volume key is encrypted with a public key in the token, and stored in
 343         the LUKS2 JSON token header area. To unlock a volume, the stored encrypted volume key will be decrypted
 344         with a private key in the token. For ECC, ECDH algorithm is used: we generate a pair of EC keys in
 345         the same EC group, then derive a shared secret using the generated private key and the public key
 346         in the token. The derived shared secret is used as a volume key. The generated public key is
 347         stored in the LUKS2 JSON token header area. The generated private key is erased. To unlock a volume,
 348         we derive the shared secret with the stored public key and a private key in the token.</para>
 349
 350         <para>In order to unlock a LUKS2 volume with an enrolled PKCS#11 security token, specify the
 351         <option>pkcs11-uri=</option> option in the respective <filename>/etc/crypttab</filename> line:</para>
 352
 353         <programlisting>myvolume /dev/sda1 - pkcs11-uri=auto</programlisting>
 354
 355         <para>See
 356         <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry> for a
 357         more comprehensive example of a <command>systemd-cryptenroll</command> invocation and its matching
 358         <filename>/etc/crypttab</filename> line.</para>
 359
 360         <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 361       </varlistentry>
 362
 363       <varlistentry>
 364         <term><option>--fido2-credential-algorithm=<replaceable>STRING</replaceable></option></term>
 365         <listitem><para>Specify COSE algorithm used in credential generation. The default value is
 366         <literal>es256</literal>. Supported values are <literal>es256</literal>, <literal>rs256</literal>
 367         and <literal>eddsa</literal>.</para>
 368
 369         <para><literal>es256</literal> denotes ECDSA over NIST P-256 with SHA-256. <literal>rs256</literal>
 370         denotes 2048-bit RSA with PKCS#1.5 padding and SHA-256. <literal>eddsa</literal> denotes
 371         EDDSA over Curve25519 with SHA-512.</para>
 372
 373         <para>Note that your authenticator may not support some algorithms.</para>
 374
 375         <xi:include href="version-info.xml" xpointer="v251"/></listitem>
 376       </varlistentry>
 377
 378       <varlistentry>
 379         <term><option>--fido2-device=<replaceable>PATH</replaceable></option></term>
 380
 381         <listitem><para>Enroll a FIDO2 security token that implements the <literal>hmac-secret</literal>
 382         extension (e.g. a YubiKey). Expects a <filename>hidraw</filename> device referring to the FIDO2
 383         device (e.g. <filename>/dev/hidraw1</filename>). Alternatively the special value
 384         <literal>auto</literal> may be specified, in order to automatically determine the device node of a
 385         currently plugged in security token (of which there must be exactly one). This automatic discovery
 386         is unsupported if <option>--unlock-fido2-device=</option> option is also specified. The special value
 387         <literal>list</literal> may be used to enumerate all suitable FIDO2 tokens currently plugged in. Note
 388         that many hardware security tokens that implement FIDO2 also implement the older PKCS#11
 389         standard. Typically FIDO2 is preferable, given it's simpler to use and more modern.</para>
 390
 391         <para>In order to unlock a LUKS2 volume with an enrolled FIDO2 security token, specify the
 392         <option>fido2-device=</option> option in the respective <filename>/etc/crypttab</filename> line:</para>
 393
 394         <programlisting>myvolume /dev/sda1 - fido2-device=auto</programlisting>
 395
 396         <para>See
 397         <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry> for a
 398         more comprehensive example of a <command>systemd-cryptenroll</command> invocation and its matching
 399         <filename>/etc/crypttab</filename> line.</para>
 400
 401         <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 402       </varlistentry>
 403
 404       <varlistentry>
 405         <term><option>--fido2-with-client-pin=<replaceable>BOOL</replaceable></option></term>
 406
 407         <listitem><para>When enrolling a FIDO2 security token, controls whether to require the user to enter
 408         a PIN when unlocking the volume (the FIDO2 <literal>clientPin</literal> feature). Defaults to
 409         <literal>yes</literal>. (Note: this setting is without effect if the security token does not support
 410         the <literal>clientPin</literal> feature at all, or does not allow enabling or disabling
 411         it.)</para>
 412
 413         <xi:include href="version-info.xml" xpointer="v249"/></listitem>
 414       </varlistentry>
 415
 416       <varlistentry>
 417         <term><option>--fido2-with-user-presence=<replaceable>BOOL</replaceable></option></term>
 418
 419         <listitem><para>When enrolling a FIDO2 security token, controls whether to require the user to
 420         verify presence (tap the token, the FIDO2 <literal>up</literal> feature) when unlocking the volume.
 421         Defaults to <literal>yes</literal>. (Note: this setting is without effect if the security token does not support
 422         the <literal>up</literal> feature at all, or does not allow enabling or disabling it.)
 423         </para>
 424
 425         <xi:include href="version-info.xml" xpointer="v249"/></listitem>
 426       </varlistentry>
 427
 428       <varlistentry>
 429         <term><option>--fido2-with-user-verification=<replaceable>BOOL</replaceable></option></term>
 430
 431         <listitem><para>When enrolling a FIDO2 security token, controls whether to require user verification
 432         when unlocking the volume (the FIDO2 <literal>uv</literal> feature). Defaults to
 433         <literal>no</literal>. (Note: this setting is without effect if the security token does not support
 434         the <literal>uv</literal> feature at all, or does not allow enabling or disabling it.)</para>
 435
 436         <xi:include href="version-info.xml" xpointer="v249"/></listitem>
 437       </varlistentry>
 438
 439       <varlistentry>
 440         <term><option>--tpm2-device=<replaceable>PATH</replaceable></option></term>
 441
 442         <listitem><para>Enroll a TPM2 security chip. Expects a device node path referring to the TPM2 chip
 443         (e.g. <filename>/dev/tpmrm0</filename>). Alternatively the special value <literal>auto</literal> may
 444         be specified, in order to automatically determine the device node of a currently discovered TPM2
 445         device (of which there must be exactly one). The special value <literal>list</literal> may be used to
 446         enumerate all suitable TPM2 devices currently discovered.</para>
 447
 448         <para>In order to unlock a LUKS2 volume with an enrolled TPM2 security chip, specify the
 449         <option>tpm2-device=</option> option in the respective <filename>/etc/crypttab</filename> line:</para>
 450
 451         <programlisting>myvolume /dev/sda1 - tpm2-device=auto</programlisting>
 452
 453         <para>See
 454         <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry> for a
 455         more comprehensive example of a <command>systemd-cryptenroll</command> invocation and its matching
 456         <filename>/etc/crypttab</filename> line.</para>
 457
 458         <para>Use <option>--tpm2-pcrs=</option> (see below) to configure which TPM2 PCR indexes to bind the
 459         enrollment to.</para>
 460
 461         <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 462       </varlistentry>
 463
 464       <varlistentry>
 465         <term><option>--tpm2-device-key=<replaceable>PATH</replaceable></option></term>
 466
 467         <listitem><para>Enroll a TPM2 security chip using its public key. Expects a path referring to the
 468         TPM2 public key in TPM2B_PUBLIC format. This cannot be used with <option>--tpm2-device=</option>, as
 469         it performs the same operation, but without connecting to the TPM2 security chip; instead the
 470         enrollment is calculated using the provided TPM2 key. This is useful in situations where the TPM2
 471         security chip is not available at the time of enrollment.</para>
 472
 473         <para>The key, in most cases, should be the Storage Root Key (SRK) from a local TPM2 security
 474         chip. If a key from a different handle (not the SRK) is used, you must specify its handle index using
 475         <option>--tpm2-seal-key-handle=</option>.</para>
 476
 477         <para>The
 478         <citerefentry><refentrytitle>systemd-tpm2-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 479         service writes the SRK to <filename>/run/systemd/tpm2-srk-public-key.tpm2b_public</filename>
 480         automatically during boot, in the correct format.</para>
 481
 482         <para>Alternatively, you may use <command>systemd-analyze srk</command> to retrieve the SRK from the
 483         TPM2 security chip explicitly. See
 484         <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 485         for details. Example:</para>
 486
 487         <programlisting>systemd-analyze srk &gt; srk.tpm2b_public</programlisting>
 488
 489         <xi:include href="version-info.xml" xpointer="v255"/></listitem>
 490       </varlistentry>
 491
 492       <varlistentry>
 493         <term><option>--tpm2-seal-key-handle=<replaceable>HANDLE</replaceable></option></term>
 494
 495         <listitem><para>Configures which parent key to use for sealing, using the TPM handle (index) of the
 496         key. This is used to "seal" (encrypt) a secret and must be used later to "unseal" (decrypt) the
 497         secret. Expects a hexadecimal 32bit integer, optionally prefixed with
 498         <literal>0x</literal>. Allowable values are any handle index in the persistent
 499         (<literal>0x81000000</literal>-<literal>0x81ffffff</literal>) or transient
 500         (<literal>0x80000000</literal>-<literal>0x80ffffff</literal>) ranges. Since transient handles are
 501         lost after a TPM reset, and may be flushed during TPM context switching, they should not be used
 502         except for very specific use cases, e.g. testing.</para>
 503
 504         <para>The default is the Storage Root Key (SRK) handle index <literal>0x81000001</literal>. A value
 505         of 0 will use the default. For the SRK handle, a new key will be created and stored in the TPM if one
 506         does not already exist; for any other handle, the key must already exist in the TPM at the specified
 507         handle index.</para>
 508
 509         <para>This should not be changed unless you know what you are doing.</para>
 510
 511         <xi:include href="version-info.xml" xpointer="v255"/></listitem>
 512       </varlistentry>
 513
 514       <varlistentry>
 515         <term><option>--tpm2-pcrs=<replaceable>PCR<optional>+PCR...</optional></replaceable></option></term>
 516
 517         <listitem><para>Configures the TPM2 PCRs (Platform Configuration Registers) to bind to when
 518         enrollment is requested via <option>--tpm2-device=</option>. Takes a list of PCR entries, where each
 519         entry starts with a name or numeric index in the range 0…23, optionally followed by
 520         <literal>:</literal> and a hash algorithm name (specifying the PCR bank), optionally followed by
 521         <literal>=</literal> and a hash digest value. Multiple PCR entries are separated by
 522         <literal>+</literal>. If not specified, the default is to use PCR 7 only. If an empty string is
 523         specified, binds the enrollment to no PCRs at all. See the table above for a list of available
 524         PCRs.</para>
 525
 526         <para>Example: <option>--tpm2-pcrs=boot-loader-code+platform-config+boot-loader-config</option>
 527         specifies that PCR registers 4, 1, and 5 should be used.</para>
 528         <para>Example: <option>--tpm2-pcrs=7:sha256</option> specifies that PCR register 7 from the SHA256
 529         bank should be used.</para>
 530         <para>Example: <option>--tpm2-pcrs=4:sha1=3a3f780f11a4b49969fcaa80cd6e3957c33b2275</option>
 531         specifies that PCR register 4 from the SHA1 bank should be used, and a hash digest value of
 532         3a3f780f11a4b49969fcaa80cd6e3957c33b2275 will be used instead of reading the current PCR
 533         value.</para>
 534
 535         <xi:include href="version-info.xml" xpointer="v248"/>
 536         </listitem>
 537       </varlistentry>
 538
 539       <varlistentry>
 540         <term><option>--tpm2-with-pin=<replaceable>BOOL</replaceable></option></term>
 541
 542         <listitem><para>When enrolling a TPM2 device, controls whether to require the user to enter a PIN
 543         when unlocking the volume in addition to PCR binding, based on TPM2 policy authentication. Defaults
 544         to <literal>no</literal>. Despite being called PIN, any character can be used, not just numbers.
 545         </para>
 546
 547         <para>Note that incorrect PIN entry when unlocking increments the TPM dictionary attack lockout
 548         mechanism, and may lock out users for a prolonged time, depending on its configuration. The lockout
 549         mechanism is a global property of the TPM, <command>systemd-cryptenroll</command> does not control or
 550         configure the lockout mechanism. You may use tpm2-tss tools to inspect or configure the dictionary
 551         attack lockout, with <citerefentry
 552         project='mankier'><refentrytitle>tpm2_getcap</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 553         and <citerefentry
 554         project='mankier'><refentrytitle>tpm2_dictionarylockout</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 555         commands, respectively.</para>
 556
 557         <xi:include href="version-info.xml" xpointer="v251"/></listitem>
 558       </varlistentry>
 559
 560       <varlistentry>
 561         <term><option>--tpm2-public-key=<replaceable>PATH</replaceable></option></term>
 562         <term><option>--tpm2-public-key-pcrs=<replaceable>PCR<optional>+PCR...</optional></replaceable></option></term>
 563         <term><option>--tpm2-signature=<replaceable>PATH</replaceable></option></term>
 564
 565         <listitem><para>Configures a TPM2 signed PCR policy to bind encryption to. The
 566         <option>--tpm2-public-key=</option> option accepts a path to a PEM encoded RSA public key, to bind
 567         the encryption to. If this is not specified explicitly, but a file
 568         <filename>tpm2-pcr-public-key.pem</filename> exists in one of the directories
 569         <filename>/etc/systemd/</filename>, <filename>/run/systemd/</filename>,
 570         <filename>/usr/lib/systemd/</filename> (searched in this order), it is automatically used. The
 571         <option>--tpm2-public-key-pcrs=</option> option takes a list of TPM2 PCR indexes to bind to (same
 572         syntax as <option>--tpm2-pcrs=</option> described above). If not specified defaults to 11 (i.e. this
 573         binds the policy to any unified kernel image for which a PCR signature can be provided).</para>
 574
 575         <para>Note the difference between <option>--tpm2-pcrs=</option> and
 576         <option>--tpm2-public-key-pcrs=</option>: the former binds decryption to the current, specific PCR
 577         values; the latter binds decryption to any set of PCR values for which a signature by the specified
 578         public key can be provided. The latter is hence more useful in scenarios where software updates shell
 579         be possible without losing access to all previously encrypted LUKS2 volumes. Like with
 580         <option>--tpm2-pcrs=</option>, names defined in the table above can also be used to specify the
 581         registers, for instance
 582         <option>--tpm2-public-key-pcrs=boot-loader-code+system-identity</option>.</para>
 583
 584         <para>The <option>--tpm2-signature=</option> option takes a path to a TPM2 PCR signature file as
 585         generated by the
 586         <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 587         tool. If this is not specified explicitly, a suitable signature file
 588         <filename>tpm2-pcr-signature.json</filename> is searched for in <filename>/etc/systemd/</filename>,
 589         <filename>/run/systemd/</filename>, <filename>/usr/lib/systemd/</filename> (in this order) and used.
 590         If a signature file is specified or found it is used to verify if the volume can be unlocked with it
 591         given the current PCR state, before the new slot is written to disk. This is intended as safety net
 592         to ensure that access to a volume is not lost if a public key is enrolled for which no valid
 593         signature for the current PCR state is available. If the supplied signature does not unlock the
 594         current PCR state and public key combination, no slot is enrolled and the operation will fail. If no
 595         signature file is specified or found no such safety verification is done.</para>
 596
 597         <xi:include href="version-info.xml" xpointer="v252"/></listitem>
 598       </varlistentry>
 599
 600       <varlistentry>
 601         <term><option>--tpm2-pcrlock=<replaceable>PATH</replaceable></option></term>
 602
 603         <listitem><para>Configures a TPM2 pcrlock policy to bind encryption to. Expects a path to a pcrlock
 604         policy file as generated by the
 605         <citerefentry><refentrytitle>systemd-pcrlock</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 606         tool. If a TPM2 device is enrolled and this option is not used but a file
 607         <filename>pcrlock.json</filename> is found in <filename>/run/systemd/</filename> or
 608         <filename>/var/lib/systemd/</filename> it is automatically used. Assign an empty string to turn this
 609         behaviour off.</para>
 610
 611         <xi:include href="version-info.xml" xpointer="v255"/></listitem>
 612       </varlistentry>
 613
 614       <varlistentry>
 615         <term><option>--wipe-slot=<replaceable>SLOT<optional>,SLOT...</optional></replaceable></option></term>
 616
 617         <listitem><para>Wipes one or more LUKS2 key slots. Takes a comma separated list of numeric slot
 618         indexes, or the special strings <literal>all</literal> (for wiping all key slots),
 619         <literal>empty</literal> (for wiping all key slots that are unlocked by an empty passphrase),
 620         <literal>password</literal> (for wiping all key slots that are unlocked by a traditional passphrase),
 621         <literal>recovery</literal> (for wiping all key slots that are unlocked by a recovery key),
 622         <literal>pkcs11</literal> (for wiping all key slots that are unlocked by a PKCS#11 token),
 623         <literal>fido2</literal> (for wiping all key slots that are unlocked by a FIDO2 token),
 624         <literal>tpm2</literal> (for wiping all key slots that are unlocked by a TPM2 chip), or any
 625         combination of these strings or numeric indexes, in which case all slots matching either are
 626         wiped. As safety precaution an operation that wipes all slots without exception (so that the volume
 627         cannot be unlocked at all anymore, unless the volume key is known) is refused.</para>
 628
 629         <para>This switch may be used alone, in which case only the requested wipe operation is executed. It
 630         may also be used in combination with any of the enrollment options listed above, in which case the
 631         enrollment is completed first, and only when successful the wipe operation executed — and the newly
 632         added slot is always excluded from the wiping. Combining enrollment and slot wiping may thus be used to
 633         update existing enrollments:</para>
 634
 635         <programlisting>systemd-cryptenroll /dev/sda1 --wipe-slot=tpm2 --tpm2-device=auto</programlisting>
 636
 637         <para>The above command will enroll the TPM2 chip, and then wipe all previously created TPM2
 638         enrollments on the LUKS2 volume, leaving only the newly created one. Combining wiping and enrollment
 639         may also be used to replace enrollments of different types, for example for changing from a PKCS#11
 640         enrollment to a FIDO2 one:</para>
 641
 642         <programlisting>systemd-cryptenroll /dev/sda1 --wipe-slot=pkcs11 --fido2-device=auto</programlisting>
 643
 644         <para>Or for replacing an enrolled empty password by TPM2:</para>
 645
 646         <programlisting>systemd-cryptenroll /dev/sda1 --wipe-slot=empty --tpm2-device=auto</programlisting>
 647
 648         <xi:include href="version-info.xml" xpointer="v248"/>
 649         </listitem>
 650       </varlistentry>
 651
 652       <xi:include href="standard-options.xml" xpointer="help" />
 653       <xi:include href="standard-options.xml" xpointer="version" />
 654     </variablelist>
 655
 656   </refsect1>
 657
 658   <refsect1>
 659     <title>Credentials</title>
 660
 661     <para><command>systemd-cryptenroll</command> supports the service credentials logic as implemented by
 662     <varname>ImportCredential=</varname>/<varname>LoadCredential=</varname>/<varname>SetCredential=</varname>
 663     (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 664     details). The following credentials are used when passed in:</para>
 665
 666     <variablelist class='system-credentials'>
 667       <varlistentry>
 668         <term><varname>cryptenroll.passphrase</varname></term>
 669         <term><varname>cryptenroll.new-passphrase</varname></term>
 670
 671         <listitem><para>May contain the passphrase to unlock the volume with/to newly enroll.</para>
 672
 673         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 674       </varlistentry>
 675
 676       <varlistentry>
 677         <term><varname>cryptenroll.tpm2-pin</varname></term>
 678         <term><varname>cryptenroll.new-tpm2-pin</varname></term>
 679
 680         <listitem><para>May contain the TPM2 PIN to unlock the volume with/to newly enroll.</para>
 681
 682         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 683       </varlistentry>
 684
 685       <varlistentry>
 686         <term><varname>cryptenroll.fido2-pin</varname></term>
 687
 688         <listitem><para>If a FIDO2 token is enrolled this may contain the PIN of the token.</para>
 689
 690         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 691       </varlistentry>
 692
 693       <varlistentry>
 694         <term><varname>cryptenroll.pkcs11-pin</varname></term>
 695
 696         <listitem><para>If a PKCS#11 token is enrolled this may contain the PIN of the token.</para>
 697
 698         <xi:include href="version-info.xml" xpointer="v256"/></listitem>
 699       </varlistentry>
 700     </variablelist>
 701   </refsect1>
 702
 703   <refsect1>
 704     <title>Exit status</title>
 705
 706     <para>On success, 0 is returned, a non-zero failure code otherwise.</para>
 707   </refsect1>
 708
 709   <refsect1>
 710     <title>Examples</title>
 711
 712     <para><citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry> and
 713     <citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 714     contain various examples employing <command>systemd-cryptenroll</command>.</para>
 715   </refsect1>
 716
 717   <refsect1>
 718     <title>See Also</title>
 719     <para><simplelist type="inline">
 720       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 721       <member><citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
 722       <member><citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
 723       <member><citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
 724       <member><citerefentry><refentrytitle>systemd-measure</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
 725      </simplelist></para>
 726   </refsect1>
 727
 728 </refentry>