1NDCTL-LOAD-KEYS(1) ndctl Manual NDCTL-LOAD-KEYS(1)
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6 ndctl-load-keys - load the kek and encrypted passphrases into the
7 keyring
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10 ndctl load-keys [<options>]
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13 The load-keys command loads the master key (kek) and the encrypted
14 passphrases for all NVDIMMs into the user keyring maintained by the
15 kernel. The command is expected to be called during initialization and
16 before the libnvdimm kernel module is loaded, typically from an initrd.
17 This is typically set up using a modprobe config that calls the command
18 before module load.
19 Note
21 All key files are expected to be in the format:
22 nvdimm_<id>_hostname
23 The '_' character is used to delimit the different components in
24 the file name. Within the hostname, the '_' character is allowed
25 since it is the last component of the file name.
26 Note
28 This command is typically never called directly by a user.
29
31 -p, --key-path=
32 Path to where key related files reside. This parameter is optional
33 and the default location is /etc/ndctl/keys.
34 -t, --tpm-handle=
36 Provide a TPM handle (should be a string such as 0x81000001). If
37 the key path (/etc/ndctl/keys) contains a file called tpm.handle
38 which contains the handle string, then this option may be left out,
39 and the tpm handle will be obtained from the file. If both are
40 present, then this option will override (but not overwrite)
41 anything that is in the file.
42
44 The Intel Device Specific Methods (DSM) specification v1.7 and v1.8 [1]
45 introduced the following security management operations: enable
46 passhprase, update passphrase, unlock DIMM, disable security, freeze
47 security, secure (crypto) erase, overwrite, master passphrase enable,
48 master passphrase update, and master passphrase secure erase.
49 The security management for NVDIMMs is comprised of two parts. The
51 front end uses the Linux key management framework (trusted and
52 encrypted keys [2]) to store the encrypted passphrases in the
53 kernel-managed keyring. The interface for this is the keyutils utility
54 which uses the key management APIs in the Linux kernel. The back end
55 takes the decrypted payload (which is the DIMM passphrase) and passes
56 it to the DIMM.
57 Unlike other DSMs which are composed by libndctl and sent to the kernel
59 via an ioctl, the security DSMs are managed through the security sysfs
60 attribute under the dimm device. A key-ID is written to the security
61 attribute and the kernel pulls the associated key material from the
62 user keyring that is maintained by the kernel.
63 The security process begins with the generation of a master key that is
65 used to seal (encrypt) the passphrase for the DIMM. There can either be
66 one common master key that is used to encrypt every DIMM’s passphrase,
67 or a separate key can be generated for each DIMM. The master key is
68 also referred to as the key-encryption-key (kek). The kek can either be
69 generated by the TPM (Trusted Platform Module) on the system, or
70 alternatively, the System Master Key can also be used as the kek
71 For testing purposes a user key with randomized payload can also be
73 used as a kek. See [2] for details. To perform any security operations,
74 it is expected that the kek has been added to the kernel’s user keyring
75 as shown in example below:
76 # keyctl show
78 Session Keyring
79 736023423 --alswrv 0 0 keyring: _ses
80 675104189 --alswrv 0 65534 \_ keyring: _uid.0
81 680187394 --alswrv 0 0 \_ trusted: nvdimm-master
82 Before performing any of the security operations, all the regions
84 associated with the DIMM in question need to be disabled. For the
85 overwrite operation, in addition to the regions, the dimm also needs to
86 be disabled.
87 [1] http://pmem.io/documents/NVDIMM_DSM_Interface-V1.8.pdf
89 [2]
90 https://www.kernel.org/doc/Documentation/security/keys/trusted-encrypted.rst
91 The following sub-sections describe specifics of each security feature.
93 UNLOCK
95 Unlock is performed by the kernel, however a preparation step must
96 happen before the unlock DSM can be issued by the kernel. It is
97 expected that from the initramfs, a setup command (ndctl load-keys) is
98 executed before the libnvdimm module is loaded by modprobe. This
99 command will inject the kek and the encrypted passphrases into the
100 kernel’s user keyring. During the probe of the libnvdimm driver, it
101 will:
102 1. Check the security state of the device and see if the DIMM is
104 locked
105 2. Request the associated encrypted passphrase from the kernel’s user
107 key ring
108 3. Use the kek to decrypt the passphrase
110 4. Create the unlock DSM, copy the decrypted payload into the DSM
112 5. Issue the DSM to unlock the DIMM
114 If the DIMM is already unlocked, the kernel will attempt to revalidate
116 the passphrase. If we fail to revalidate the passphrase, the kernel
117 will freeze the security and disallow any further security
118 configuration changes. A kernel module parameter is available to
119 override this behavior.
120 SETUP USER PASSPHRASE
122 To setup the passphrase for a DIMM, it is expected that the kek to be
123 used is present in the kernel’s user keyring. The kek encrypts the DIMM
124 passphrase using the enc32 key format. The plaintext passphrase is
125 never provided by or made visible to the user. It is instead randomly
126 generated by the kernel and userspace does not have access to it. Upon
127 encryption, a binary blob of the passphrase is written to the
128 passphrase blob storage directory (/etc/ndctl/keys). The user is
129 responsible for backing up the passphrase blobs to a secure location.
130 UPDATE USER PASSPHRASE
132 The update user passphrase operation uses the same DSM command as
133 enable user passphrase. Most of the work is done on the key management
134 side. The user has the option of providing a new kek for the new
135 passphrase, but continuing to use the existing kek is also acceptable.
136 The following operations are performed for update-passphrase:
137 1. Remove the encrypted passphrase from the kernel’s user keyring.
139 2. Rename the passphrase blob to old.
141 3. Load this old passphrase blob into the keyring with an "old" name.
143 4. Create the new passphrase and encrypt with the kek.
145 5. Send DSM with the old and new decrypted passphrases.
147 6. Remove old passphrase and the passphrase blob from the keyring.
149 REMOVE USER PASSPHRASE
151 The key-ID for the passphrase to be removed is written to sysfs. The
152 kernel then sends the DSM to disable security, and the passphrase is
153 then removed from the keyring, and the associated passphrase blob is
154 deleted.
155 CRYPTO (SECURE) ERASE
157 This operation is similar to remove-passphrase. The kernel issues a
158 WBINVD instruction before and after the operation to ensure no data
159 corruption from a stale CPU cache. Use ndctl’s sanitize-dimm command
160 with the --crypto-erase option to perform this operation.
161 OVERWRITE
163 This is invoked using --overwrite option for ndctl sanitize-dimm. The
164 overwrite operation wipes the entire NVDIMM. The operation can take a
165 significant amount of time. NOTE: When the command returns
166 successfully, it just means overwrite has been successfully started,
167 and not that the overwrite is complete. Subsequently, 'ndctl
168 wait-overwrite’can be used to wait for the NVDIMMs that are performing
169 overwrite. Upon successful completion of an overwrite, the WBINVD
170 instruction is issued by the kernel. If both --crypto-erase and
171 --overwrite options are supplied, then crypto-erase is performed before
172 overwrite.
173 SECURITY FREEZE
175 This operation does not require a passphrase. This will cause any
176 security command other than a status query to be locked out until the
177 next boot.
178 MASTER PASSPHRASE SETUP, UPDATE, and CRYPTO ERASE
180 These operations are similar to the user passphrase enable and update.
181 The only difference is that a different passphrase is used. The master
182 passphrase has no relation to the master key (kek) which is used for
183 encryption of either passphrase.
184
186 Copyright (c) 2016 - 2019, Intel Corporation. License GPLv2: GNU GPL
187 version 2 http://gnu.org/licenses/gpl.html. This is free software: you
188 are free to change and redistribute it. There is NO WARRANTY, to the
189 extent permitted by law.
190ndctl 2020-03-24 NDCTL-LOAD-KEYS(1)