1NDCTL-LOAD-KEYS(1)               ndctl Manual               NDCTL-LOAD-KEYS(1)
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NAME

6       ndctl-load-keys - load the kek and encrypted passphrases into the
7       keyring
8

SYNOPSIS

10       ndctl load-keys [<options>]
11

DESCRIPTION

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
20           Note
21           All key files are expected to be in the format:
22           nvdimm_<id>_hostname The ‘'_’ character is used to delimit the
23           different components in the file name. Within the hostname, the
24           ‘'_’ character is allowed since it is the last component of the
25           file name.
26
27           Note
28           This command is typically never called directly by a user.
29

OPTIONS

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
35       -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

THEORY OF OPERATION

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
50       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
58       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
64       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
72       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
77
78           .ft C
79           # keyctl show
80           Session Keyring
81            736023423 --alswrv      0     0  keyring: _ses
82            675104189 --alswrv      0 65534   \_ keyring: _uid.0
83            680187394 --alswrv      0     0       \_ trusted: nvdimm-master
84           .ft
85
86
87       Before performing any of the security operations, all the regions
88       associated with the DIMM in question need to be disabled. For the
89       overwrite operation, in addition to the regions, the dimm also needs to
90       be disabled.
91
92       [1] http://pmem.io/documents/NVDIMM_DSM_Interface-V1.8.pdf [2]
93       https://www.kernel.org/doc/Documentation/security/keys/trusted-encrypted.rst
94
95       The following sub-sections describe specifics of each security feature.
96
97   UNLOCK
98       Unlock is performed by the kernel, however a preparation step must
99       happen before the unlock DSM can be issued by the kernel. It is
100       expected that from the initramfs, a setup command (ndctl load-keys) is
101       executed before the libnvdimm module is loaded by modprobe. This
102       command will inject the kek and the encrypted passphrases into the
103       kernel’s user keyring. During the probe of the libnvdimm driver, it
104       will:
105
106        1. Check the security state of the device and see if the DIMM is
107           locked
108
109        2. Request the associated encrypted passphrase from the kernel’s user
110           key ring
111
112        3. Use the kek to decrypt the passphrase
113
114        4. Create the unlock DSM, copy the decrypted payload into the DSM
115
116        5. Issue the DSM to unlock the DIMM
117
118       If the DIMM is already unlocked, the kernel will attempt to revalidate
119       the passphrase. If we fail to revalidate the passphrase, the kernel
120       will freeze the security and disallow any further security
121       configuration changes. A kernel module parameter is available to
122       override this behavior.
123
124   SETUP USER PASSPHRASE
125       To setup the passphrase for a DIMM, it is expected that the kek to be
126       used is present in the kernel’s user keyring. The kek encrypts the DIMM
127       passphrase using the enc32 key format. The plaintext passphrase is
128       never provided by or made visible to the user. It is instead randomly
129       generated by the kernel and userspace does not have access to it. Upon
130       encryption, a binary blob of the passphrase is written to the
131       passphrase blob storage directory (/etc/ndctl/keys). The user is
132       responsible for backing up the passphrase blobs to a secure location.
133
134   UPDATE USER PASSPHRASE
135       The update user passphrase operation uses the same DSM command as
136       enable user passphrase. Most of the work is done on the key management
137       side. The user has the option of providing a new kek for the new
138       passphrase, but continuing to use the existing kek is also acceptable.
139       The following operations are performed for update-passphrase:
140
141        1. Remove the encrypted passphrase from the kernel’s user keyring.
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143        2. Rename the passphrase blob to old.
144
145        3. Load this old passphrase blob into the keyring with an "old" name.
146
147        4. Create the new passphrase and encrypt with the kek.
148
149        5. Send DSM with the old and new decrypted passphrases.
150
151        6. Remove old passphrase and the passphrase blob from the keyring.
152
153   REMOVE USER PASSPHRASE
154       The key-ID for the passphrase to be removed is written to sysfs. The
155       kernel then sends the DSM to disable security, and the passphrase is
156       then removed from the keyring, and the associated passphrase blob is
157       deleted.
158
159   CRYPTO (SECURE) ERASE
160       This operation is similar to remove-passphrase. The kernel issues a
161       WBINVD instruction before and after the operation to ensure no data
162       corruption from a stale CPU cache. Use ndctl’s sanitize-dimm command
163       with the --crypto-erase option to perform this operation.
164
165   OVERWRITE
166       This is invoked using --overwrite option for ndctl sanitize-dimm. The
167       overwrite operation wipes the entire NVDIMM. The operation can take a
168       significant amount of time. NOTE: When the command returns
169       successfully, it just means overwrite has been successfully started,
170       and not that the overwrite is complete. Subsequently, 'ndctl
171       wait-overwrite’can be used to wait for the NVDIMMs that are performing
172       overwrite. Upon successful completion of an overwrite, the WBINVD
173       instruction is issued by the kernel. If both --crypto-erase and
174       --overwrite options are supplied, then crypto-erase is performed before
175       overwrite.
176
177   SECURITY FREEZE
178       This operation does not require a passphrase. This will cause any
179       security command other than a status query to be locked out until the
180       next boot.
181
182   MASTER PASSPHRASE SETUP, UPDATE, and CRYPTO ERASE
183       These operations are similar to the user passphrase enable and update.
184       The only difference is that a different passphrase is used. The master
185       passphrase has no relation to the master key (kek) which is used for
186       encryption of either passphrase.
187
189       Copyright © 2016 - 2020, Intel Corporation. License GPLv2: GNU GPL
190       version 2 http://gnu.org/licenses/gpl.html. This is free software: you
191       are free to change and redistribute it. There is NO WARRANTY, to the
192       extent permitted by law.
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196ndctl 71.1                        01/26/2021                NDCTL-LOAD-KEYS(1)
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