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69 lines
3.4 KiB
69 lines
3.4 KiB
14 years ago
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# Directions for creating the kernel master key that will be used for
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# encrypting/decrypting other keys.
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# A trusted key is a TPM random number, which is only ever exposed to
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# userspace as an encrypted datablob. A trusted key can be sealed to a
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# set of PCR values. For more details on trusted keys, refer to the
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# kernel keys-trusted-encrypted.txt documentation.
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$ keyctl add trusted kmk-trusted "new 32" @u
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801713097
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# For those systems which don't have a TPM, but want to experiment with
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# encrypted keys, create a user key of 32 random bytes. Unlike
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# trusted/encrypted keys, user type key data is visible to userspace.
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$ keyctl add user kmk-user "`dd if=/dev/urandom bs=1 count=32 2>/dev/null`" @u
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144468621
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# Save the kernel master key (trusted type):
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$ su -c 'keyctl pipe `keyctl search @u trusted kmk-trusted` > /etc/keys/kmk-trusted.blob'
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# or (user type):
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$ su -c 'keyctl pipe `keyctl search @u user kmk-user` > /etc/keys/kmk-user.blob'
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# A useful feature of trusted keys is that it is possible to prevent their
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# unsealing at later time by providing the parameter 'pcrlock=<pcrnum>' when
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# loading it, which causes the PCR #<pcrnum> to be extended with a random value.
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# Actually, the <pcrnum> variable is set to '11' to let users experiment with
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# this feature by using a register that is never extended during the boot,
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# making the re-sealing not necessary. In the future, the kernel master key will
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# be sealed to the PCR #14 which is extended, according to the TrustedGRUB
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# documentation[1], to the measure of the kernel and the initial ramdisk.
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# The kernel master key path name and type can be set in one of the following
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# ways (specified in the order in which variables are overwritten):
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1) use default values:
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--------------------------------------------------------------------------
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MULTIKERNELMODE="NO"
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MASTERKEYTYPE="trusted"
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MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}.blob"
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--------------------------------------------------------------------------
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2) create the configuration file '/etc/sysconfig/masterkey' to override the
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value of one or all variables;
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3) specify these parameters in the kernel command line:
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- masterkey=</kernel/master/key/path>, to override the MASTERKEY variable;
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- masterkeytype=<kernel-master-key-type>, to override the MASTERKEYTYPE variable.
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# The variable MULTIKERNELMODE has been introduced to support multi boot
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# configurations, where a trusted/user key is tied to a specific kernel and
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# initial ramdisk. In this case, setting MULTIKERNELMODE to 'YES' will cause the
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# kernel version to be added to the default masterkey path name, so that the
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# MASTERKEY variable should not be overridden each time a different kernel is
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# chosen. The default value of MASTERKEY will be equal to:
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--------------------------------------------------------------------------
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MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}-$(uname -r).blob"
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--------------------------------------------------------------------------
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# The masterkey path name also depends on the value of MASTERKEYTYPE, as reported
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# in the default values for defined variables. For example, if only MASTERKEYTYPE
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# is overridden by setting it to 'user' in the configuration file or from the
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# kernel command line, the value of MASTERKEY will be:
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--------------------------------------------------------------------------
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MASTERKEY="/etc/keys/kmk-user.blob"
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--------------------------------------------------------------------------
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[1] https://projects.sirrix.com/trac/trustedgrub/
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