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812862db LP |
1 | --- |
2 | title: JSON User Records | |
3 | category: Interfaces | |
4 | layout: default | |
5 | --- | |
6 | ||
7 | # JSON User Records | |
8 | ||
9 | systemd optionally processes user records that go beyond the classic UNIX (or | |
10 | glibc NSS) `struct passwd`. Various components of systemd are able to provide | |
11 | and consume records in a more extensible format of a dictionary of key/value | |
12 | pairs, encoded as JSON. Specifically: | |
13 | ||
14 | 1. [`systemd-homed.service`](https://www.freedesktop.org/software/systemd/man/systemd-homed.service.html) | |
15 | manages `human` user home directories and embeds these JSON records | |
16 | directly in the home directory images (see [Home | |
afcb3e75 | 17 | Directories](https://systemd.io/HOME_DIRECTORY) for details). |
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18 | |
19 | 2. [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
20 | processes these JSON records for users that log in, and applies various | |
21 | settings to the activated session, including environment variables, nice | |
22 | levels and more. | |
23 | ||
24 | 3. [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html) | |
25 | processes these JSON records of users that log in, and applies various | |
26 | resource management settings to the per-user slice units it manages. This | |
27 | allows setting global limits on resource consumption by a specific user. | |
28 | ||
29 | 4. [`nss-systemd`](https://www.freedesktop.org/software/systemd/man/nss-systemd.html) | |
30 | is a glibc NSS module that synthesizes classic NSS records from these JSON | |
31 | records, providing full backwards compatibility with the classic UNIX APIs | |
32 | both for look-up and enumeration. | |
33 | ||
34 | 5. The service manager (PID 1) exposes dynamic users (i.e. users synthesized as | |
35 | effect of `DynamicUser=` in service unit files) as these advanced JSON | |
36 | records, making them discoverable to the rest of the system. | |
37 | ||
38 | 6. [`systemd-userdbd.service`](https://www.freedesktop.org/software/systemd/man/systemd-userdbd.service.html) | |
39 | is a small service that can translate UNIX/glibc NSS records to these JSON | |
40 | user records. It also provides a unified [Varlink](https://varlink.org/) API | |
41 | for querying and enumerating records of this type, optionally acquiring them | |
42 | from various other services. | |
43 | ||
44 | JSON user records may contain various fields that are not available in `struct | |
45 | passwd`, and are extensible for other applications. For example, the record may | |
46 | contain information about: | |
47 | ||
48 | 1. Additional security credentials (PKCS#11 security token information, | |
49 | biometrical authentication information, SSH public key information) | |
50 | ||
51 | 2. Additional user metadata, such as a picture, email address, location string, | |
52 | preferred language or timezone | |
53 | ||
54 | 3. Resource Management settings (such as CPU/IO weights, memory and tasks | |
55 | limits, classic UNIX resource limits or nice levels) | |
56 | ||
57 | 4. Runtime parameters such as environment variables or the `nodev`, `noexec`, | |
58 | `nosuid` flags to use for the home directory | |
59 | ||
60 | 5. Information about where to mount the home directory from | |
61 | ||
62 | And various other things. The record is intended to be extensible, for example | |
63 | the following extensions are envisioned: | |
64 | ||
65 | 1. Windows network credential information | |
66 | ||
67 | 2. Information about default IMAP, SMTP servers to use for this user | |
68 | ||
69 | 3. Parental control information to enforce on this user | |
70 | ||
71 | 4. Default parameters for backup applications and similar | |
72 | ||
73 | Similar to JSON User Records there are also [JSON Group | |
56b3eddb | 74 | Records](https://systemd.io/GROUP_RECORD) that encapsulate UNIX groups. |
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75 | |
76 | JSON User Records may be transferred or written to disk in various protocols | |
77 | and formats. To inquire about such records defined on the local system use the | |
56b3eddb | 78 | [User/Group Lookup API via Varlink](https://systemd.io/USER_GROUP_API). |
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79 | |
80 | ## Why JSON? | |
81 | ||
82 | JSON is nicely extensible and widely used. In particular it's easy to | |
83 | synthesize and process with numerous programming languages. It's particularly | |
84 | popular in the web communities, which hopefully should make it easy to link | |
85 | user credential data from the web and from local systems more closely together. | |
86 | ||
87 | ## General Structure | |
88 | ||
89 | The JSON user records generated and processed by systemd follow a general | |
90 | structure, consisting of seven distinct "sections". Specifically: | |
91 | ||
92 | 1. Various fields are placed at the top-level of user record (the `regular` | |
93 | section). These are generally fields that shall apply unconditionally to the | |
94 | user in all contexts, are portable and not security sensitive. | |
95 | ||
96 | 2. A number of fields are located in the `privileged` section (a sub-object of | |
97 | the user record). Fields contained in this object are security sensitive, | |
98 | i.e. contain information that the user and the administrator should be able | |
99 | to see, but other users should not. In many ways this matches the data | |
100 | stored in `/etc/shadow` in classic Linux user accounts, i.e. includes | |
101 | password hashes and more. Algorithmically, when a user record is passed to | |
102 | an untrusted client, by monopolizing such sensitive records in a single | |
103 | object field we can easily remove it from view. | |
104 | ||
105 | 3. A number of fields are located in objects inside the `perMachine` section | |
106 | (an array field of the user record). Primarily these are resource | |
107 | management-related fields, as those tend to make sense on a specific system | |
108 | only, e.g. limiting a user's memory use to 1G only makes sense on a specific | |
109 | system that has more than 1G of memory. Each object inside the `perMachine` | |
110 | array comes with a `matchMachineId` or `matchHostname` field which indicate | |
111 | which systems to apply the listed settings to. Note that many fields | |
112 | accepted in the `perMachine` section can also be set at the top level (the | |
113 | `regular` section), where they define the fallback if no matching object in | |
114 | `perMachine` is found. | |
115 | ||
116 | 4. Various fields are located in the `binding` section (a sub-sub-object of the | |
117 | user record; an intermediary object is inserted which is keyed by the | |
118 | machine ID of the host). Fields included in this section "bind" the object | |
119 | to a specific system. They generally include non-portable information about | |
120 | paths or UID assignments, that are true on a specific system, but not | |
121 | necessarily on others, and which are managed automatically by some user | |
122 | record manager (such as `systemd-homed`). Data in this section is considered | |
123 | part of the user record only in the local context, and is generally not | |
124 | ported to other systems. Due to that it is not included in the reduced user | |
125 | record the cryptographic signature defined in the `signature` section is | |
126 | calculated on. In `systemd-homed` this section is also removed when the | |
127 | user's record is stored in the `~/.identity` file in the home directory, so | |
128 | that every system with access to the home directory can manage these | |
129 | `binding` fields individually. Typically, the binding section is persisted | |
130 | to the local disk. | |
131 | ||
132 | 5. Various fields are located in the `status` section (a sub-sub-object of the | |
133 | user record, also with an intermediary object between that is keyed by the | |
134 | machine ID, similar to the way the `binding` section is organized). This | |
135 | section is augmented during runtime only, and never persisted to disk. The | |
136 | idea is that this section contains information about current runtime | |
137 | resource usage (for example: currently used disk space of the user), that | |
138 | changes dynamically but is otherwise immediately associated with the user | |
139 | record and for many purposes should be considered to be part of the user | |
140 | record. | |
141 | ||
142 | 6. The `signature` section contains one or more cryptographic signatures of a | |
143 | reduced version of the user record. This is used to ensure that only user | |
144 | records defined by a specific source are accepted on a system, by validating | |
145 | the signature against the set of locally accepted signature public keys. The | |
146 | signature is calculated from the JSON user record with all sections removed, | |
147 | except for `regular`, `privileged`, `perMachine`. Specifically, `binding`, | |
148 | `status`, `signature` itself and `secret` are removed first and thus not | |
149 | covered by the signature. This section is optional, and is only used when | |
150 | cryptographic validation of user records is required (as it is by | |
151 | `systemd-homed.service` for example). | |
152 | ||
153 | 7. The `secret` section contains secret user credentials, such as password or | |
154 | PIN information. This data is never persisted, and never returned when user | |
155 | records are inquired by a client, privileged or not. This data should only | |
156 | be included in a user record very briefly, for example when certain very | |
157 | specific operations are executed. For example, in tools such as | |
158 | `systemd-homed` this section may be included in user records, when creating | |
159 | a new home directory, as passwords and similar credentials need to be | |
160 | provided to encrypt the home directory with. | |
161 | ||
162 | Here's a tabular overview of the sections and their properties: | |
163 | ||
164 | | Section | Included in Signature | Persistent | Security Sensitive | Contains Host-Specific Data | | |
165 | |------------|-----------------------|------------|--------------------|-----------------------------| | |
166 | | regular | yes | yes | no | no | | |
167 | | privileged | yes | yes | yes | no | | |
168 | | perMachine | yes | yes | no | yes | | |
169 | | binding | no | yes | no | yes | | |
170 | | status | no | no | no | yes | | |
171 | | signature | no | yes | no | no | | |
172 | | secret | no | no | yes | no | | |
173 | ||
174 | Note that services providing user records to the local system are free to | |
175 | manage only a subset of these sections and never include the others in | |
176 | them. For example, a service that has no concept of signed records (for example | |
177 | because the records it manages are inherently trusted anyway) does not have to | |
178 | bother with the `signature` section. A service that only defines records in a | |
179 | strictly local context and without signatures doesn't have to deal with the | |
180 | `perMachine` or `binding` sections and can include its data exclusively in the | |
181 | regular section. A service that uses a separate, private channel for | |
182 | authenticating users (or that doesn't have a concept of authentication at all) | |
183 | does not need to to be concerned with the `secret` section of user records, as | |
184 | the fields included therein are only useful when executing authentication | |
185 | operations natively against JSON user records. | |
186 | ||
58345a23 | 187 | The `systemd-homed` manager uses all seven sections for various |
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188 | purposes. Inside the home directories (and if the LUKS2 backend is used, also |
189 | in the LUKS2 header) a user record containing the `regular`, `privileged`, | |
190 | `perMachine` and `signature` sections is stored. `systemd-homed` also stores a | |
191 | version of the record on the host, with the same four sections and augmented | |
192 | with an additional, fifth `binding` section. When a local client enquires about | |
193 | a user record managed by `systemd-homed` the service will add in some | |
194 | additional information about the user and home directory in the `status` | |
195 | section — this version is only transferred via IPC and never written to | |
196 | disk. Finally the `secret` section is used during authentication operations via | |
197 | IPC to transfer the user record along with its authentication tokens in one go. | |
198 | ||
199 | ## Fields in the `regular` section | |
200 | ||
201 | As mentioned, the `regular` section's fields are placed at the top level | |
202 | object. The following fields are currently defined: | |
203 | ||
204 | `userName` → The UNIX user name for this record. Takes a string with a valid | |
205 | UNIX user name. This field is the only mandatory field, all others are | |
206 | optional. Corresponds with the `pw_name` field of of `struct passwd` and the | |
207 | `sp_namp` field of `struct spwd` (i.e. the shadow user record stored in | |
208 | `/etc/shadow`). | |
209 | ||
210 | `realm` → The "realm" a user is defined in. This concept allows distinguishing | |
211 | users with the same name that originate in different organizations or | |
212 | installations. This should take a string in DNS domain syntax, but doesn't have | |
213 | to refer to an actual DNS domain (though it is recommended to use one for | |
214 | this). The idea is that the user `lpoetter` in the `redhat.com` realm might be | |
215 | distinct from the same user in the `poettering.hq` realm. User records for the | |
216 | same user name that have different realm fields are considered referring to | |
217 | different users. When updating a user record it is required that any new | |
218 | version has to match in both `userName` and `realm` field. This field is | |
219 | optional, when unset the user should not be considered part of any realm. A | |
220 | user record with a realm set is never compatible (for the purpose of updates, | |
221 | see above) with a user record without one set, even if the `userName` field matches. | |
222 | ||
223 | `realName` → The real name of the user, a string. This should contain the user's | |
224 | real ("human") name, and corresponds loosely to the GECOS field of classic UNIX | |
225 | user records. When converting a `struct passwd` to a JSON user record this | |
226 | field is initialized from GECOS (i.e. the `pw_gecos` field), and vice versa | |
227 | when converting back. That said, unlike GECOS this field is supposed to contain | |
228 | only the real name and no other information. | |
229 | ||
230 | `emailAddress` → The email address of the user, formatted as | |
231 | string. [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
232 | initializes the `$EMAIL` environment variable from this value for all login | |
233 | sessions. | |
234 | ||
235 | `iconName` → The name of an icon picked by the user, for example for the | |
236 | purpose of an avatar. This must be a string, and should follow the semantics | |
237 | defined in the [Icon Naming | |
238 | Specification](https://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html). | |
239 | ||
240 | `location` → A free-form location string describing the location of the user, | |
241 | if that is applicable. It's probably wise to use a location string processable | |
242 | by geo-location subsystems, but this is not enforced nor required. Example: | |
243 | `Berlin, Germany` or `Basement, Room 3a`. | |
244 | ||
245 | `disposition` → A string, one of `intrinsic`, `system`, `dynamic`, `regular`, | |
246 | `container`, `reserved`. If specified clarifies the disposition of the user, | |
247 | i.e. the context it is defined in. For regular, "human" users this should be | |
248 | `regular`, for system users (i.e. users that system services run under, and | |
249 | similar) this should be `system`. The `intrinsic` disposition should be used | |
250 | only for the two users that have special meaning to the OS kernel itself, | |
251 | i.e. the `root` and `nobody` users. The `container` string should be used for | |
252 | users that are used by an OS container, and hence will show up in `ps` listings | |
253 | and such, but are only defined in container context. Finally `reserved` should | |
254 | be used for any users outside of these use-cases. Note that this property is | |
255 | entirely optional and applications are assumed to be able to derive the | |
256 | disposition of a user automatically from a record even in absence of this | |
257 | field, based on other fields, for example the numeric UID. By setting this | |
258 | field explicitly applications can override this default determination. | |
259 | ||
260 | `lastChangeUSec` → An unsigned 64bit integer value, referring to a timestamp in µs | |
261 | since the epoch 1970, indicating when the user record (specifically, any of the | |
262 | `regular`, `privileged`, `perMachine` sections) was last changed. This field is | |
263 | used when comparing two records of the same user to identify the newer one, and | |
264 | is used for example for automatic updating of user records, where appropriate. | |
265 | ||
266 | `lastPasswordChangeUSec` → Similar, also an unsigned 64bit integer value, | |
267 | indicating the point in time the password (or any authentication token) of the | |
268 | user was last changed. This corresponds to the `sp_lstchg` field of `struct | |
269 | spwd`, i.e. the matching field in the user shadow database `/etc/shadow`, | |
270 | though provides finer resolution. | |
271 | ||
272 | `shell` → A string, referring to the shell binary to use for terminal logins of | |
273 | this user. This corresponds with the `pw_shell` field of `struct passwd`, and | |
274 | should contain an absolute file system path. For system users not suitable for | |
275 | terminal log-in this field should not be set. | |
276 | ||
277 | `umask` → The `umask` to set for the user's login sessions. Takes an | |
278 | integer. Note that usually on UNIX the umask is noted in octal, but JSON's | |
279 | integers are generally written in decimal, hence in this context we denote it | |
280 | umask in decimal too. The specified value should be in the valid range for | |
281 | umasks, i.e. 0000…0777 (in octal as typical in UNIX), or 0…511 (in decimal, how | |
282 | it actually appears in the JSON record). This `umask` is automatically set by | |
283 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
284 | for all login sessions of the user. | |
285 | ||
286 | `environment` → An array of strings, each containing an environment variable | |
287 | and its value to set for the user's login session, in a format compatible with | |
288 | [`putenv()`](http://man7.org/linux/man-pages/man3/putenv.3.html). Any | |
289 | environment variable listed here is automatically set by | |
290 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
291 | for all login sessions of the user. | |
292 | ||
293 | `timeZone` → A string indicating a preferred timezone to use for the user. When | |
294 | logging in | |
295 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
296 | will automatically initialize the `$TZ` environment variable from this | |
297 | string. The string should be a `tzdata` compatible location string, for | |
298 | example: `Europe/Berlin`. | |
299 | ||
300 | `preferredLanguage` → A string indicating the preferred language/locale for the | |
301 | user. When logging in | |
302 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
303 | will automatically initialize the `$LANG` environment variable from this | |
304 | string. The string hence should be in a format compatible with this environment | |
305 | variable, for example: `de_DE.UTF8`. | |
306 | ||
307 | `niceLevel` → An integer value in the range -20…19. When logging in | |
308 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
309 | will automatically initialize the login process' nice level to this value with, | |
310 | which is then inherited by all the user's processes, see | |
311 | [`setpriority()`](http://man7.org/linux/man-pages/man2/setpriority.2.html) for | |
312 | more information. | |
313 | ||
314 | `resourceLimits` → An object, where each key refers to a Linux resource limit | |
315 | (such as `RLIMIT_NOFILE` and similar). Their values should be an object with | |
316 | two keys `cur` and `max` for the soft and hard resource limit. When logging in | |
317 | [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html) | |
318 | will automatically initialize the login process' resource limits to these | |
319 | values, which is then inherited by all the user's processes, see | |
320 | [`setrlimit()`](http://man7.org/linux/man-pages/man2/setrlimit.2.html) for more | |
321 | information. | |
322 | ||
323 | `locked` → A boolean value. If true the user account is locked, the user may | |
324 | not log in. If this field is missing it should be assumed to be false, | |
325 | i.e. logins are permitted. This field corresponds to the `sp_expire` field of | |
326 | `struct spwd` (i.e. the `/etc/shadow` data for a user) being set to zero or | |
327 | one. | |
328 | ||
329 | `notBeforeUSec` → An unsigned 64bit integer value, indicating a time in µs since | |
330 | the UNIX epoch (1970) before which the record should be considered invalid for | |
331 | the purpose of logging in. | |
332 | ||
333 | `notAfterUSec` → Similar, but indicates the point in time *after* which logins | |
334 | shall not be permitted anymore. This corresponds to the `sp_expire` field of | |
335 | `struct spwd`, when it is set to a value larger than one, but provides finer | |
336 | granularity. | |
337 | ||
338 | `storage` → A string, one of `classic`, `luks`, `directory`, `subvolume`, | |
339 | `fscrypt`, `cifs`. Indicates the storage mechanism for the user's home | |
340 | directory. If `classic` the home directory is a plain directory as in classic | |
341 | UNIX. When `directory`, the home directory is a regular directory, but the | |
342 | `~/.identity` file in it contains the user's user record, so that the directory | |
343 | is self-contained. Similar, `subvolume` is a `btrfs` subvolume that also | |
344 | contains a `~/.identity` user record; `fscrypt` is an `fscrypt`-encrypted | |
345 | directory, also containing the `~/.identity` user record; `luks` is a per-user | |
346 | LUKS volume that is mounted as home directory, and `cifs` a home directory | |
347 | mounted from a Windows File Share. The five latter types are primarily used by | |
348 | `systemd-homed` when managing home directories, but may be used if other | |
349 | managers are used too. If this is not set `classic` is the implied default. | |
350 | ||
351 | `diskSize` → An unsigned 64bit integer, indicating the intended home directory | |
352 | disk space in bytes to assign to the user. Depending on the selected storage | |
353 | type this might be implement differently: for `luks` this is the intended size | |
354 | of the file system and LUKS volume, while for the others this likely translates | |
355 | to classic file system quota settings. | |
356 | ||
357 | `diskSizeRelative` → Similar to `diskSize` but takes a relative value, but | |
358 | specifies a fraction of the available disk space on the selected storage medium | |
359 | to assign to the user. This unsigned integer value is normalized to 2^32 = | |
360 | 100%. | |
361 | ||
362 | `skeletonDirectory` → Takes a string with the absolute path to the skeleton | |
363 | directory to populate a new home directory from. This is only used when a home | |
364 | directory is first created, and defaults to `/etc/skel` if not defined. | |
365 | ||
366 | `accessMode` → Takes an unsigned integer in the range 0…511 indicating the UNIX | |
367 | access mask for the home directory when it is first created. | |
368 | ||
369 | `tasksMax` → Takes an unsigned 64bit integer indicating the maximum number of | |
370 | tasks the user may start in parallel during system runtime. This value is | |
371 | enforced on all tasks (i.e. processes and threads) the user starts or that are | |
372 | forked off these processes regardless if the change user identity (for example | |
373 | by setuid binaries/`su`/`sudo` and | |
374 | similar). [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html) | |
375 | enforces this by setting the `TasksMax` slice property for the user's slice | |
376 | `user-$UID.slice`. | |
377 | ||
378 | `memoryHigh`/`memoryMax` → These take unsigned 64bit integers indicating upper | |
379 | memory limits for all processes of the user (plus all processes forked off them | |
380 | that might have changed user identity), in bytes. Enforced by | |
381 | [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html), | |
382 | similar to `tasksMax`. | |
383 | ||
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384 | `cpuWeight`/`ioWeight` → These take unsigned integers in the range 1…10000 |
385 | (defaults to 100) and configure the CPU and IO scheduling weights for the | |
386 | user's processes as a whole. Also enforced by | |
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387 | [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html), |
388 | similar to `tasksMax`, `memoryHigh` and `memoryMax`. | |
389 | ||
390 | `mountNoDevices`/`mountNoSuid`/`mountNoExecute` → Three booleans that control | |
391 | the `nodev`, `nosuid`, `noexec` mount flags of the user's home | |
392 | directories. Note that these booleans are only honored if the home directory | |
393 | is managed by a subsystem such as `systemd-homed.service` that automatically | |
394 | mounts home directories on login. | |
395 | ||
396 | `cifsDomain` → A string indicating the Windows File Sharing domain (CIFS) to | |
397 | use. This is generally useful, but particularly when `cifs` is used as storage | |
398 | mechanism for the user's home directory, see above. | |
399 | ||
400 | `cifsUserName` → A string indicating the Windows File Sharing user name (CIFS) | |
401 | to associate this user record with. This is generally useful, but particularly | |
402 | useful when `cifs` is used as storage mechanism for the user's home directory, | |
403 | see above. | |
404 | ||
405 | `cifsService` → A string indicating the Windows File Share service (CIFS) to | |
406 | mount as home directory of the user on login. | |
407 | ||
408 | `imagePath` → A string with an absolute file system path to the file, directory | |
409 | or block device to use for storage backing the home directory. If the `luks` | |
410 | storage is used this refers to the loopback file or block device node to store | |
411 | the LUKS volume on. For `fscrypt`, `directory`, `subvolume` this refers to the | |
412 | directory to bind mount as home directory on login. Not defined for `classic` | |
413 | or `cifs`. | |
414 | ||
415 | `homeDirectory` → A string with an absolute file system path to the home | |
416 | directory. This is where the image indicated in `imagePath` is mounted to on | |
417 | login and thus indicates the application facing home directory while the home | |
418 | directory is active, and is what the user's `$HOME` environment variable is set | |
419 | to during log-in. It corresponds to the `pw_dir` field of `struct passwd`. | |
420 | ||
421 | `uid` → An unsigned integer in the range 0…4294967295: the numeric UNIX user ID (UID) to | |
422 | use for the user. This corresponds to the `pw_uid` field of `struct passwd`. | |
423 | ||
424 | `gid` → An unsigned integer in the range 0…4294967295: the numeric UNIX group | |
425 | ID (GID) to use for the user. This corresponds to the `pw_gid` field of | |
426 | `struct passwd`. | |
427 | ||
428 | `memberOf` → An array of strings, each indicating a UNIX group this user shall | |
429 | be a member of. The listed strings must be valid group names, but it is not | |
430 | required that all groups listed exist in all contexts: any entry for which no | |
431 | group exists should be silently ignored. | |
432 | ||
433 | `fileSystemType` → A string, one of `ext4`, `xfs`, `btrfs` (possibly others) to | |
434 | use as file system for the user's home directory. This is primarily relevant | |
435 | when the storage mechanism used is `luks` as a file system to use inside the | |
436 | LUKS container must be selected. | |
437 | ||
438 | `partitionUuid` → A string containing a lower-case, text-formatted UUID, referencing | |
439 | the GPT partition UUID the home directory is located in. This is primarily | |
440 | relevant when the storage mechanism used is `luks`. | |
441 | ||
442 | `luksUuid` → A string containing a lower-case, text-formatted UUID, referencing | |
443 | the LUKS volume UUID the home directory is located in. This is primarily | |
444 | relevant when the storage mechanism used is `luks`. | |
445 | ||
446 | `fileSystemUuid` → A string containing a lower-case, text-formatted UUID, | |
447 | referencing the file system UUID the home directory is located in. This is | |
448 | primarily relevant when the storage mechanism used is `luks`. | |
449 | ||
450 | `luksDiscard` → A boolean. If true and `luks` storage is used controls whether | |
451 | the loopback block devices, LUKS and the file system on top shall be used in | |
452 | `discard` mode, i.e. erased sectors should always be returned to the underlying | |
453 | storage. If false and `luks` storage is used turns this behavior off. In | |
454 | addition, depending on this setting an `FITRIM` or `fallocate()` operation is | |
455 | executed to make sure the image matches the selected option. | |
456 | ||
457 | `luksCipher` → A string, indicating the cipher to use for the LUKS storage mechanism. | |
458 | ||
459 | `luksCipherMode` → A string, selecting the cipher mode to use for the LUKS storage mechanism. | |
460 | ||
461 | `luksVolumeKeySize` → An unsigned integer, indicating the volume key length in | |
462 | bytes to use for the LUKS storage mechanism. | |
463 | ||
464 | `luksPbkdfHashAlgorithm` → A string, selecting the hash algorithm to use for | |
465 | the PBKDF operation for the LUKS storage mechanism. | |
466 | ||
467 | `luksPbkdfType` → A string, indicating the PBKDF type to use for the LUKS storage mechanism. | |
468 | ||
469 | `luksPbkdfTimeCostUSec` → An unsigned 64bit integer, indicating the intended | |
470 | time cost for the PBKDF operation, when the LUKS storage mechanism is used, in | |
471 | µs. | |
472 | ||
473 | `luksPbkdfMemoryCost` → An unsigned 64bit integer, indicating the intended | |
474 | memory cost for the PBKDF operation, when LUKS storage is used, in bytes. | |
475 | ||
476 | `luksPbkdfParallelThreads` → An unsigned 64bit integer, indicating the intended | |
477 | required parallel threads for the PBKDF operation, when LUKS storage is used. | |
478 | ||
479 | `service` → A string declaring the service that defines or manages this user | |
480 | record. It is recommended to use reverse domain name notation for this. For | |
481 | example, if `systemd-homed` manages a user a string of `io.systemd.Home` is | |
482 | used for this. | |
483 | ||
484 | `rateLimitIntervalUSec` → An unsigned 64bit integer that configures the | |
485 | authentication rate limiting enforced on the user account. This specifies a | |
486 | timer interval (in µs) within which to count authentication attempts. When the | |
487 | counter goes above the value configured n `rateLimitIntervalBurst` log-ins are | |
488 | temporarily refused until the interval passes. | |
489 | ||
490 | `rateLimitIntervalBurst` → An unsigned 64bit integer, closely related to | |
491 | `rateLimitIntervalUSec`, that puts a limit on authentication attempts within | |
492 | the configured time interval. | |
493 | ||
494 | `enforcePasswordPolicy` → A boolean. Configures whether to enforce the system's | |
495 | password policy when creating the home directory for the user or changing the | |
496 | user's password. By default the policy is enforced, but if this field is false | |
497 | it is bypassed. | |
498 | ||
499 | `autoLogin` → A boolean. If true the user record is marked as suitable for | |
500 | auto-login. Systems are supposed to automatically log in a user marked this way | |
501 | during boot, if there's exactly one user on it defined this way. | |
502 | ||
503 | `stopDelayUSec` → An unsigned 64bit integer, indicating the time in µs the | |
504 | per-user service manager is kept around after the user fully logged out. This | |
505 | value is honored by | |
506 | [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html). If | |
507 | set to zero the per-user service manager is immediately terminated when the | |
508 | user logs out, and longer values optimize high-frequency log-ins as the | |
509 | necessary work to set up and tear down a log-in is reduced if the service | |
510 | manager stays running. | |
511 | ||
512 | `killProcesses` → A boolean. If true all processes of the user are | |
513 | automatically killed when the user logs out. This is enforced by | |
514 | [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html). If | |
515 | false any processes left around when the user logs out are left running. | |
516 | ||
517 | `passwordChangeMinUSec`/`passwordChangeMaxUSec` → An unsigned 64bit integer, | |
518 | encoding how much time has to pass at least/at most between password changes of | |
519 | the user. This corresponds with the `sp_min` and `sp_max` fields of `struct | |
520 | spwd` (i.e. the `/etc/shadow` entries of the user), but offers finer | |
521 | granularity. | |
522 | ||
523 | `passwordChangeWarnUSec` → An unsigned 64bit integer, encoding how much time to | |
524 | warn the user before their password expires, in µs. This corresponds with the | |
525 | `sp_warn` field of `struct spwd`. | |
526 | ||
527 | `passwordChangeInactiveUSec` → An unsigned 64bit integer, encoding how much | |
528 | time has to pass after the password expired that the account is | |
529 | deactivated. This corresponds with the `sp_inact` field of `struct spwd`. | |
530 | ||
531 | `passwordChangeNow` → A boolean. If true the user has to change their password | |
532 | on next login. This corresponds with the `sp_lstchg` field of `struct spwd` | |
533 | being set to zero. | |
534 | ||
535 | `pkcs11TokenUri` → An array of strings, each with an RFC 7512 compliant PKCS#11 | |
536 | URI referring to security token (or smart card) of some form, that shall be | |
537 | associated with the user and may be used for authentication. The URI is used to | |
538 | search for an X.509 certificate and associated private key that may be used to | |
539 | decrypt an encrypted secret key that is used to unlock the user's account (see | |
540 | below). It's undefined how precise the URI is: during log-in it is tested | |
541 | against all plugged in security tokens and if there's exactly one matching | |
542 | private key found with it it is used. | |
543 | ||
e1ef1e5d | 544 | `privileged` → An object, which contains the fields of the `privileged` section |
812862db LP |
545 | of the user record, see below. |
546 | ||
547 | `perMachine` → An array of objects, which contain the `perMachine` section of | |
548 | the user record, and thus fields to apply on specific systems only, see below. | |
549 | ||
550 | `binding` → An object, keyed by machine IDs formatted as strings, pointing | |
551 | to objects that contain the `binding` section of the user record, | |
552 | i.e. additional fields that bind the user record to a specific machine, see | |
553 | below. | |
554 | ||
555 | `status` → An object, keyed by machine IDs formatted as strings, pointing to | |
556 | objects that contain the `status` section of the user record, i.e. additional | |
557 | runtime fields that expose the current status of the user record on a specific | |
558 | system, see below. | |
559 | ||
560 | `signature` → An array of objects, which contain cryptographic signatures of | |
561 | the user record, i.e. the fields of the `signature` section of the user record, | |
562 | see below. | |
563 | ||
564 | `secret` → An object, which contains the fields of the `secret` section of the | |
565 | user record, see below. | |
566 | ||
567 | ## Fields in the `privileged` section | |
568 | ||
569 | As mentioned, the `privileged` section is encoded in a sub-object of the user | |
570 | record top-level object, in the `privileged` field. Any data included in this | |
571 | object shall only be visible to the administrator and the user themselves, and | |
572 | be suppressed implicitly when other users get access to a user record. It thus | |
573 | takes the role of the `/etc/shadow` records for each user, which has similarly | |
574 | restrictive access semantics. The following fields are currently defined: | |
575 | ||
576 | `passwordHint` → A user-selected password hint in free-form text. This should | |
577 | be a string like "What's the name of your first pet?", but is entirely for the | |
578 | user to choose. | |
579 | ||
580 | `hashPassword` → An array of strings, each containing a hashed UNIX password | |
581 | string, in the format | |
582 | [`crypt(3)`](http://man7.org/linux/man-pages/man3/crypt.3.html) generates. This | |
583 | corresponds with `sp_pwdp` field of `struct spwd` (and in a way the `pw_passwd` | |
584 | field of `struct passwd`). | |
585 | ||
586 | `sshAuthorizedKeys` → An array of strings, each listing an SSH public key that | |
587 | is authorized to access the account. The strings should follow the same format | |
588 | as the lines in the traditional `~/.ssh/authorized_key` file. | |
589 | ||
590 | `pkcs11EncryptedKey` → An array of objects. Each element of the array should be | |
591 | an object consisting of three string fields: `uri` shall contain a PKCS#11 | |
592 | security token URI, `data` shall contain a Base64 encoded encrypted key and | |
593 | `hashedPassword` shall contain a UNIX password hash to test the key | |
594 | against. Authenticating with a security token against this account shall work | |
595 | as follows: the encrypted secret key is converted from its Base64 | |
596 | representation into binary, then decrypted with the PKCS#11 `C_Decrypt()` | |
597 | function of the PKCS#11 module referenced by the specified URI, using the | |
598 | private key found on the same token. The resulting decrypted key is then | |
599 | Base64-encoded and tested against the specified UNIX hashed password. The | |
600 | Base64-enceded decrypted key may also be used to unlock further resources | |
601 | during log-in, for example the LUKS or `fscrypt` storage backend. It is | |
602 | generally recommended that for each entry in `pkcs11EncryptedKey` there's also | |
603 | a matching one in `pkcs11TokenUri` and vice versa, with the same URI, appearing | |
604 | in the same order, but this should not be required by applications processing | |
605 | user records. | |
606 | ||
607 | ## Fields in the `perMachine` section | |
608 | ||
609 | As mentioned, the `perMachine` section contains settings that shall apply to | |
610 | specific systems only. This is primarily interesting for resource management | |
611 | properties as they tend to require a per-system focus, however they may be used | |
612 | for other purposes too. | |
613 | ||
614 | The `perMachine` field in the top-level object is an array of objects. When | |
615 | processing the user record first the various fields on the top-level object | |
616 | should be used. Then this array should be iterated in order, and the various | |
617 | settings be applied that match either the indicated machine ID or host | |
618 | name. There may be multiple array entries that match a specific system, in | |
619 | which case all the object's setting should be applied. If the same option is | |
620 | set in the top-level object as in a per-machine object the latter wins and | |
621 | entirely undoes the setting in the top-level object (i.e. no merging of | |
622 | properties that are arrays themselves is done). If the same option is set in | |
623 | multiple per-machine objects the one specified later in the array wins (and | |
624 | here too no merging of individual fields is done, the later field always wins | |
625 | in full). | |
626 | ||
627 | The following fields are defined in this section: | |
628 | ||
629 | `matchMachineId` → An array of strings with each a formatted 128bit ID in | |
630 | hex. If any of the specified IDs match the system's local machine ID | |
631 | (i.e. matches `/etc/machine-id`) the fields in this object are honored. | |
632 | ||
633 | `matchHostname` → An array of string with a each a valid hostname. If any of | |
634 | the specified hostnames match the system's local hostname, the fields in this | |
635 | object are honored. If both `matchHostname` and `matchMachineId` are used | |
636 | within the same array entry, the object is honored when either match succeeds, | |
637 | i.e. the two match types are combined in OR, not in AND. | |
638 | ||
639 | These two are the only two fields specific to this section. All other fields | |
640 | that may be used in this section are identical to the equally named ones in the | |
641 | `regular` section (i.e. at the top-level object). Specifically, these are: | |
642 | ||
643 | `iconName`, `location`, `shell`, `umask`, `environment`, `timeZone`, | |
644 | `preferredLanguage`, `niceLevel`, `resourceLimits`, `locked`, `notBeforeUSec`, | |
645 | `notAfterUSec`, `storage`, `diskSize`, `diskSizeRelative`, `skeletonDirectory`, | |
646 | `accessMode`, `tasksMax`, `memoryHigh`, `memoryMax`, `cpuWeight`, `ioWeight`, | |
647 | `mountNoDevices`, `mountNoSuid`, `mountNoExecute`, `cifsDomain`, | |
648 | `cifsUserName`, `cifsService`, `imagePath`, `uid`, `gid`, `memberOf`, | |
649 | `fileSystemType`, `partitionUuid`, `luksUuid`, `fileSystemUuid`, `luksDiscard`, | |
650 | `luksCipher`, `luksCipherMode`, `luksVolumeKeySize`, `luksPbkdfHashAlgorithm`, | |
651 | `luksPbkdfType`, `luksPbkdfTimeCostUSec`, `luksPbkdfMemoryCost`, | |
652 | `luksPbkdfParallelThreads`, `rateLimitIntervalUSec`, `rateLimitBurst`, | |
653 | `enforcePasswordPolicy`, `autoLogin`, `stopDelayUSec`, `killProcesses`, | |
654 | `passwordChangeMinUSec`, `passwordChangeMaxUSec`, `passwordChangeWarnUSec`, | |
655 | `passwordChangeInactiveUSec`, `passwordChangeNow`, `pkcs11TokenUri`. | |
656 | ||
657 | ## Fields in the `binding` section | |
658 | ||
659 | As mentioned, the `binding` section contains additional fields about the user | |
660 | record, that bind it to the local system. These fields are generally used by a | |
661 | local user manager (such as `systemd-homed.service`) to add in fields that make | |
662 | sense in a local context but not necessarily in a global one. For example, a | |
663 | user record that contains no `uid` field in the regular section is likely | |
664 | extended with one in the `binding` section to assign a local UID if no global | |
665 | UID is defined. | |
666 | ||
667 | All fields in the `binding` section only make sense in a local context and are | |
668 | suppressed when the user record is ported between systems. The `binding` section | |
669 | is generally persisted on the system but not in the home directories themselves | |
670 | and the home directory is supposed to be fully portable and thus not contain | |
671 | the information that `binding` is supposed to contain that binds the portable | |
672 | record to a specific system. | |
673 | ||
674 | The `binding` sub-object on the top-level user record object is keyed by the | |
675 | machine ID the binding is intended for, which point to an object with the | |
676 | fields of the bindings. These fields generally match fields that may also be | |
677 | defined in the `regular` and `perMachine` sections, however override | |
678 | both. Usually, the `binding` value should not contain settings different from | |
679 | those set via `regular` or `perMachine`, however this might happen if some | |
680 | settings are not supported locally (think: `fscrypt` is recorded as intended | |
681 | storage mechanism in the `regular` section, but the local kernel does not | |
682 | support `fscrypt`, hence `directory` was chosen as implicit fallback), or have | |
683 | been changed in the `regular` section through updates (e.g. a home directory | |
684 | was created with `luks` as storage mechanism but later the user record was | |
685 | updated to prefer `subvolume`, which however doesn't change the actual storage | |
686 | used already which is pinned in the `binding` section). | |
687 | ||
688 | The following fields are defined in the `binding` section. They all have an | |
689 | identical format and override their equally named counterparts in the `regular` | |
690 | and `perMachine` sections: | |
691 | ||
692 | `imagePath`, `homeDirectory`, `partitionUuid`, `luksUuid`, `fileSystemUuid`, | |
693 | `uid`, `gid`, `storage`, `fileSystemType`, `luksCipher`, `luksCipherMode`, | |
694 | `luksVolumeKeySize`. | |
695 | ||
696 | ## Fields in the `status` section | |
697 | ||
698 | As mentioned, the `status` section contains additional fields about the user | |
699 | record that are exclusively acquired during runtime, and that expose runtime | |
700 | metrics of the user and similar metadata that shall not be persisted but are | |
701 | only acquired "on-the-fly" when requested. | |
702 | ||
703 | This section is arranged similarly to the `binding` section: the `status` | |
704 | sub-object of the top-level user record object is keyed by the machine ID, | |
705 | which points to the object with the fields defined here. The following fields | |
706 | are defined: | |
707 | ||
708 | `diskUsage` → An unsigned 64bit integer. The currently used disk space of the | |
709 | home directory in bytes. This value might be determined in different ways, | |
710 | depending on the selected storage mechanism. For LUKS storage this is the file | |
711 | size of the loopback file or block device size. For the | |
712 | directory/subvolume/fscrypt storage this is the current disk space used as | |
713 | reported by the file system quota subsystem. | |
714 | ||
715 | `diskFree` → An unsigned 64bit integer, denoting the number of "free" bytes in | |
716 | the disk space allotment, i.e. usually the difference between the disk size as | |
717 | reported by `diskSize` and the used already as reported in `diskFree`, but | |
718 | possibly skewed by metadata sizes, disk compression and similar. | |
719 | ||
720 | `diskSize` → An unsigned 64bit integer, denoting the disk space currently | |
721 | allotted to the user, in bytes. Depending on the storage mechanism this can mean | |
722 | different things (see above). In contrast to the top-level field of the same | |
723 | (or the one in the `perMachine` section), this field reports the current size | |
724 | allotted to the user, not the intended one. The values may differ when user | |
725 | records are updated without the home directory being re-sized. | |
726 | ||
727 | `diskCeiling`/`diskFloor` → Unsigned 64bit integers indicating upper and lower | |
728 | bounds when changing the `diskSize` value, in bytes. These values are typically | |
729 | derived from the underlying data storage, and indicate in which range the home | |
730 | directory may be re-sized in, i.e. in which sensible range the `diskSize` value | |
731 | should be kept. | |
732 | ||
733 | `state` → A string indicating the current state of the home directory. The | |
734 | precise set of values exposed here are up to the service managing the home | |
735 | directory to define (i.e. are up to the service identified with the `service` | |
736 | field below). However, it is recommended to stick to a basic vocabulary here: | |
737 | `inactive` for a home directory currently not mounted, `absent` for a home | |
738 | directory that cannot be mounted currently because it does not exist on the | |
739 | local system, `active` for a home directory that is currently mounted and | |
740 | accessible. | |
741 | ||
742 | `service` → A string identifying the service that manages this user record. For | |
743 | example `systemd-homed.service` sets this to `io.systemd.Home` to all user | |
744 | records it manages. This is particularly relevant to define clearly the context | |
745 | in which `state` lives, see above. Note that this field also exists on the | |
746 | top-level object (i.e. in the `regular` section), which it overrides. The | |
747 | `regular` field should be used if conceptually the user record can only be | |
748 | managed by the specified service, and this `status` field if it can | |
749 | conceptually be managed by different managers, but currently is managed by the | |
750 | specified one. | |
751 | ||
752 | `signedLocally` → A boolean. If true indicates that the user record is signed | |
753 | by a public key for which the private key is available locally. This means that | |
754 | the user record may be modified locally as it can be re-signed with the private | |
755 | key. If false indicates that the user record is signed by a public key | |
756 | recognized by the local manager but whose private key is not available | |
757 | locally. This means the user record cannot be modified locally as it couldn't | |
758 | be signed afterwards. | |
759 | ||
760 | `goodAuthenticationCounter` → An unsigned 64bit integer. This counter is | |
761 | increased by one on every successful authentication attempt, i.e. an | |
762 | authentication attempt where a security token of some form was presented and it | |
763 | was correct. | |
764 | ||
765 | `badAuthenticationCounter` → An unsigned 64bit integer. This counter is | |
766 | increased by one on every unsuccessfully authentication attempt, i.e. an | |
767 | authentication attempt where a security token of some form was presented and it | |
768 | was incorrect. | |
769 | ||
770 | `lastGoodAuthenticationUSec` → An unsigned 64bit integer, indicating the time | |
771 | of the last successful authentication attempt in µs since the UNIX epoch (1970). | |
772 | ||
773 | `lastBadAuthenticationUSec` → Similar, but the timestamp of the last | |
774 | unsuccessfully authentication attempt. | |
775 | ||
776 | `rateLimitBeginUSec` → An unsigned 64bit integer: the µs timestamp since the | |
777 | UNIX epoch (1970) where the most recent rate limiting interval has been | |
778 | started, as configured with `rateLimitIntervalUSec`. | |
779 | ||
780 | `rateLimitCount` → An unsigned 64bit integer, counting the authentication | |
781 | attempts in the current rate limiting interval, see above. If this counter | |
782 | grows beyond the value configured in `rateLimitBurst` authentication attempts | |
783 | are temporarily refused. | |
784 | ||
785 | `removable` → A boolean value. If true the manager of this user record | |
786 | determined the home directory being on removable media. If false it was | |
787 | determined the home directory is in internal built-in media. (This is used by | |
788 | `systemd-logind.service` to automatically pick the right default value for | |
789 | `stopDelayUSec` if the field is not explicitly specified: for home directories | |
790 | on removable media the delay is selected very low to minimize the chance the | |
791 | home directory remains in unclean state if the storage device is removed from | |
792 | the system by the user). | |
793 | ||
794 | ## Fields in the `signature` section | |
795 | ||
796 | As mentioned, the `signature` section of the user record may contain one or | |
797 | more cryptographic signatures of the user record. Like all others, this section | |
798 | is optional, and only used when cryptographic validation of user records shall | |
799 | be used. Specifically, all user records managed by `systemd-homed.service` will | |
800 | carry such signatures and the service refuses managing user records that come | |
801 | without signature or with signatures not recognized by any locally defined | |
802 | public key. | |
803 | ||
804 | The `signature` field in the top-level user record object is an array of | |
805 | objects. Each object encapsulates one signature and has two fields: `data` and | |
806 | `key` (both are strings). The `data` field contains the actual signature, | |
807 | encoded in base64, the `key` field contains a copy of the public key whose | |
808 | private key was used to make the signature, in PEM format. Currently only | |
809 | signatures with Ed25519 keys are defined. | |
810 | ||
811 | Before signing the user record should be brought into "normalized" form, | |
812 | i.e. the keys in all objects should be sorted alphabetically. All redundant | |
813 | white-space and newlines should be removed and the JSON text then signed. | |
814 | ||
815 | The signatures only cover the `regular`, `perMachine` and `privileged` sections | |
816 | of the user records, all other sections (include `signature` itself), are | |
817 | removed before the signature is calculated. | |
818 | ||
819 | Rationale for signing and threat model: while a multi-user operating system | |
820 | like Linux strives for being sufficiently secure even after a user acquired a | |
821 | local login session reality tells us this is not the case. Hence it is | |
822 | essential to restrict carefully which users may gain access to a system and | |
823 | which ones shall not. A minimal level of trust must be established between | |
824 | system, user record and the user themselves before a log-in request may be | |
825 | permitted. In particular if the home directory is provided in its own LUKS2 | |
826 | encapsulated file system it is essential this trust is established before the | |
827 | user logs in (and hence the file system mounted), since file system | |
828 | implementations on Linux are well known to be relatively vulnerable to rogue | |
829 | disk images. User records and home directories in many context are expected to | |
830 | be something shareable between multiple systems, and the transfer between them | |
831 | might not happen via exclusively trusted channels. Hence it's essential that | |
832 | the user record is not manipulated between uses. Finally, resource management | |
833 | (which may be done by the various fields of the user record) is security | |
834 | sensitive, since it should forcefully lock the user into the assigned resource | |
835 | usage and not allow them to use more. The requirement of being able to trust | |
836 | the user record data combined with the potential transfer over untrusted | |
837 | channels suggest a cryptographic signature mechanism where only user records | |
838 | signed by a recognized key are permitted to log in locally. | |
839 | ||
840 | Note that other mechanisms for establishing sufficient trust exist too, and are | |
841 | perfectly valid as well. For example, systems like LDAP/ActiveDirectory | |
842 | generally insist on user record transfer from trusted servers via encrypted TLS | |
843 | channels only. Or traditional UNIX users created locally in `/etc/passwd` never | |
844 | exist outside of the local trusted system, hence transfer and trust in the | |
845 | source are not an issue. The major benefit of operating with signed user | |
846 | records is that they are self-sufficiently trusted, not relying on a secure | |
847 | channel for transfer, and thus being compatible with a more distributed model | |
848 | of home directory transfer, including on USB sticks and such. | |
849 | ||
850 | ## Fields in the `secret` section | |
851 | ||
852 | As mentioned, the `secret` section of the user record should never be persisted | |
853 | nor transferred across machines. It is only defined in short-lived operations, | |
854 | for example when a user record is first created or registered, as the secret | |
855 | key data needs to be available to derive encryption keys from and similar. | |
856 | ||
857 | The `secret` field of the top-level user record contains the following fields: | |
858 | ||
859 | `password` → an array of strings, each containing a plain text password. | |
860 | ||
861 | `pkcs11Pin` → an array of strings, each containing a plain text PIN, suitable | |
862 | for unlocking PKCS#11 security tokens that require that. | |
863 | ||
864 | `pkcs11ProtectedAuthenticationPathPermitted` → a boolean. If set to true allows | |
865 | the receiver to use the PKCS#11 "protected authentication path" (i.e. a | |
866 | physical button/touch element on the security token) for authenticating the | |
867 | user. If false or unset authentication this way shall not be attempted. | |
868 | ||
869 | ## Mapping to `struct passwd` and `struct spwd` | |
870 | ||
871 | When mapping classic UNIX user records (i.e. `struct passwd` and `struct spwd`) | |
872 | to JSON user records the following mappings should be applied: | |
873 | ||
874 | | Structure | Field | Section | Field | Condition | | |
875 | |-----------------|-------------|--------------|------------------------------|----------------------------| | |
876 | | `struct passwd` | `pw_name` | `regular` | `userName` | | | |
877 | | `struct passwd` | `pw_passwd` | `privileged` | `password` | (See notes below) | | |
878 | | `struct passwd` | `pw_uid` | `regular` | `uid` | | | |
879 | | `struct passwd` | `pw_gid` | `regular` | `gid` | | | |
880 | | `struct passwd` | `pw_gecos` | `regular` | `realName` | | | |
881 | | `struct passwd` | `pw_dir` | `regular` | `homeDirectory` | | | |
882 | | `struct passwd` | `pw_shell` | `regular` | `shell` | | | |
883 | | `struct spwd` | `sp_namp` | `regular` | `userName` | | | |
884 | | `struct spwd` | `sp_pwdp` | `privileged` | `password` | (See notes below) | | |
885 | | `struct spwd` | `sp_lstchg` | `regular` | `lastPasswordChangeUSec` | (if `sp_lstchg` > 0) | | |
886 | | `struct spwd` | `sp_lstchg` | `regular` | `passwordChangeNow` | (if `sp_lstchg` == 0) | | |
887 | | `struct spwd` | `sp_min` | `regular` | `passwordChangeMinUSec` | | | |
888 | | `struct spwd` | `sp_max` | `regular` | `passwordChangeMaxUSec` | | | |
889 | | `struct spwd` | `sp_warn` | `regular` | `passwordChangeWarnUSec` | | | |
890 | | `struct spwd` | `sp_inact` | `regular` | `passwordChangeInactiveUSec` | | | |
891 | | `struct spwd` | `sp_expire` | `regular` | `locked` | (if `sp_expire` in [0, 1]) | | |
892 | | `struct spwd` | `sp_expire` | `regular` | `notAfterUSec` | (if `sp_expire` > 1) | | |
893 | ||
894 | At this time almost all Linux machines employ shadow passwords, thus the | |
895 | `pw_passwd` field in `struct passwd` is set to `"x"`, and the actual password | |
896 | is stored in the shadow entry `struct spwd`'s field `sp_pwdp`. | |
897 | ||
898 | ## Extending These Records | |
899 | ||
900 | User records following this specifications are supposed to be extendable for | |
901 | various applications. In general, subsystems are free to introduce their own | |
902 | keys, as long as: | |
903 | ||
904 | * Care should be taken to place the keys in the right section, i.e. the most | |
905 | appropriate for the data field. | |
906 | ||
907 | * Care should be taken to avoid namespace clashes. Please prefix your fields | |
908 | with a short identifier of your project to avoid ambiguities and | |
909 | incompatibilities. | |
910 | ||
911 | * This specification is supposed to be a living specification. If you need | |
912 | additional fields, please consider submitting them upstream for inclusion in | |
913 | this specification. If they are reasonably universally useful, it would be | |
914 | best to list them here. | |
915 | ||
916 | ## Examples | |
917 | ||
918 | The shortest valid user record looks like this: | |
919 | ||
920 | ```json | |
921 | { | |
922 | "userName" : "u" | |
923 | } | |
924 | ``` | |
925 | ||
926 | A reasonable user record for a system user might look like this: | |
927 | ||
928 | ```json | |
929 | { | |
930 | "userName" : "httpd", | |
931 | "uid" : 473, | |
932 | "gid" : 473, | |
933 | "disposition" : "system", | |
934 | "locked" : true | |
935 | } | |
936 | ``` | |
937 | ||
938 | A fully featured user record associated with a home directory managed by | |
939 | `systemd-homed.service` might look like this: | |
940 | ||
941 | ```json | |
942 | { | |
943 | "autoLogin" : true, | |
944 | "binding" : { | |
945 | "15e19cf24e004b949ddaac60c74aa165" : { | |
946 | "fileSystemType" : "ext4", | |
947 | "fileSystemUuid" : "758e88c8-5851-4a2a-b88f-e7474279c111", | |
948 | "gid" : 60232, | |
949 | "homeDirectory" : "/home/grobie", | |
950 | "imagePath" : "/home/grobie.home", | |
951 | "luksCipher" : "aes", | |
952 | "luksCipherMode" : "xts-plain64", | |
953 | "luksUuid" : "e63581ba-79fb-4226-b9de-1888393f7573", | |
954 | "luksVolumeKeySize" : 32, | |
955 | "partitionUuid" : "41f9ce04-c827-4b74-a981-c669f93eb4dc", | |
956 | "storage" : "luks", | |
957 | "uid" : 60232 | |
958 | } | |
959 | }, | |
960 | "disposition" : "regular", | |
961 | "enforcePasswordPolicy" : false, | |
962 | "lastChangeUSec" : 1565950024279735, | |
963 | "memberOf" : [ | |
964 | "wheel" | |
965 | ], | |
966 | "privileged" : { | |
967 | "hashedPassword" : [ | |
968 | "$6$WHBKvAFFT9jKPA4k$OPY4D4TczKN/jOnJzy54DDuOOagCcvxxybrwMbe1SVdm.Bbr.zOmBdATp.QrwZmvqyr8/SafbbQu.QZ2rRvDs/" | |
969 | ] | |
970 | }, | |
971 | "signature" : [ | |
972 | { | |
973 | "data" : "LU/HeVrPZSzi3MJ0PVHwD5m/xf51XDYCrSpbDRNBdtF4fDVhrN0t2I2OqH/1yXiBidXlV0ptMuQVq8KVICdEDw==", | |
974 | "key" : "-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEA/QT6kQWOAMhDJf56jBmszEQQpJHqDsGDMZOdiptBgRk=\n-----END PUBLIC KEY-----\n" | |
975 | } | |
976 | ], | |
977 | "userName" : "grobie", | |
978 | "status" : { | |
979 | "15e19cf24e004b949ddaac60c74aa165" : { | |
980 | "goodAuthenticationCounter" : 16, | |
981 | "lastGoodAuthenticationUSec" : 1566309343044322, | |
982 | "rateLimitBeginUSec" : 1566309342340723, | |
983 | "rateLimitCount" : 1, | |
984 | "state" : "inactive", | |
985 | "service" : "io.systemd.Home", | |
986 | "diskSize" : 161118667776, | |
987 | "diskCeiling" : 190371729408, | |
988 | "diskFloor" : 5242880, | |
989 | "signedLocally" : true | |
990 | } | |
991 | } | |
992 | } | |
993 | ``` | |
994 | ||
995 | When `systemd-homed.service` manages a home directory it will also include a | |
996 | version of the user record in the home directory itself in the `~/.identity` | |
997 | file. This version lacks the `binding` and `status` sections which are used for | |
998 | local management of the user, but are not intended to be portable between | |
999 | systems. It would hence look like this: | |
1000 | ||
1001 | ```json | |
1002 | { | |
1003 | "autoLogin" : true, | |
1004 | "disposition" : "regular", | |
1005 | "enforcePasswordPolicy" : false, | |
1006 | "lastChangeUSec" : 1565950024279735, | |
1007 | "memberOf" : [ | |
1008 | "wheel" | |
1009 | ], | |
1010 | "privileged" : { | |
1011 | "hashedPassword" : [ | |
1012 | "$6$WHBKvAFFT9jKPA4k$OPY4D4TczKN/jOnJzy54DDuOOagCcvxxybrwMbe1SVdm.Bbr.zOmBdATp.QrwZmvqyr8/SafbbQu.QZ2rRvDs/" | |
1013 | ] | |
1014 | }, | |
1015 | "signature" : [ | |
1016 | { | |
1017 | "data" : "LU/HeVrPZSzi3MJ0PVHwD5m/xf51XDYCrSpbDRNBdtF4fDVhrN0t2I2OqH/1yXiBidXlV0ptMuQVq8KVICdEDw==", | |
1018 | "key" : "-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEA/QT6kQWOAMhDJf56jBmszEQQpJHqDsGDMZOdiptBgRk=\n-----END PUBLIC KEY-----\n" | |
1019 | } | |
1020 | ], | |
1021 | "userName" : "grobie", | |
1022 | } | |
1023 | ``` |