1084 lines
59 KiB
Markdown
1084 lines
59 KiB
Markdown
---
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title: JSON User Records
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category: Users, Groups and Home Directories
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layout: default
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---
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# JSON User Records
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systemd optionally processes user records that go beyond the classic UNIX (or
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glibc NSS) `struct passwd`. Various components of systemd are able to provide
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and consume records in a more extensible format of a dictionary of key/value
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pairs, encoded as JSON. Specifically:
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1. [`systemd-homed.service`](https://www.freedesktop.org/software/systemd/man/systemd-homed.service.html)
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manages `human` user home directories and embeds these JSON records
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directly in the home directory images (see [Home
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Directories](https://systemd.io/HOME_DIRECTORY) for details).
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2. [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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processes these JSON records for users that log in, and applies various
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settings to the activated session, including environment variables, nice
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levels and more.
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3. [`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html)
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processes these JSON records of users that log in, and applies various
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resource management settings to the per-user slice units it manages. This
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allows setting global limits on resource consumption by a specific user.
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4. [`nss-systemd`](https://www.freedesktop.org/software/systemd/man/nss-systemd.html)
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is a glibc NSS module that synthesizes classic NSS records from these JSON
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records, providing full backwards compatibility with the classic UNIX APIs
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both for look-up and enumeration.
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5. The service manager (PID 1) exposes dynamic users (i.e. users synthesized as
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effect of `DynamicUser=` in service unit files) as these advanced JSON
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records, making them discoverable to the rest of the system.
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6. [`systemd-userdbd.service`](https://www.freedesktop.org/software/systemd/man/systemd-userdbd.service.html)
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is a small service that can translate UNIX/glibc NSS records to these JSON
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user records. It also provides a unified [Varlink](https://varlink.org/) API
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for querying and enumerating records of this type, optionally acquiring them
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from various other services.
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JSON user records may contain various fields that are not available in `struct
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passwd`, and are extensible for other applications. For example, the record may
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contain information about:
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1. Additional security credentials (PKCS#11 security token information,
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biometrical authentication information, SSH public key information)
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2. Additional user metadata, such as a picture, email address, location string,
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preferred language or timezone
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3. Resource Management settings (such as CPU/IO weights, memory and tasks
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limits, classic UNIX resource limits or nice levels)
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4. Runtime parameters such as environment variables or the `nodev`, `noexec`,
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`nosuid` flags to use for the home directory
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5. Information about where to mount the home directory from
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And various other things. The record is intended to be extensible, for example
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the following extensions are envisioned:
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1. Windows network credential information
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2. Information about default IMAP, SMTP servers to use for this user
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3. Parental control information to enforce on this user
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4. Default parameters for backup applications and similar
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Similar to JSON User Records there are also [JSON Group
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Records](https://systemd.io/GROUP_RECORD) that encapsulate UNIX groups.
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JSON User Records may be transferred or written to disk in various protocols
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and formats. To inquire about such records defined on the local system use the
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[User/Group Lookup API via Varlink](https://systemd.io/USER_GROUP_API).
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## Why JSON?
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JSON is nicely extensible and widely used. In particular it's easy to
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synthesize and process with numerous programming languages. It's particularly
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popular in the web communities, which hopefully should make it easy to link
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user credential data from the web and from local systems more closely together.
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## General Structure
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The JSON user records generated and processed by systemd follow a general
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structure, consisting of seven distinct "sections". Specifically:
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1. Various fields are placed at the top-level of user record (the `regular`
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section). These are generally fields that shall apply unconditionally to the
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user in all contexts, are portable and not security sensitive.
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2. A number of fields are located in the `privileged` section (a sub-object of
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the user record). Fields contained in this object are security sensitive,
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i.e. contain information that the user and the administrator should be able
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to see, but other users should not. In many ways this matches the data
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stored in `/etc/shadow` in classic Linux user accounts, i.e. includes
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password hashes and more. Algorithmically, when a user record is passed to
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an untrusted client, by monopolizing such sensitive records in a single
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object field we can easily remove it from view.
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3. A number of fields are located in objects inside the `perMachine` section
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(an array field of the user record). Primarily these are resource
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management-related fields, as those tend to make sense on a specific system
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only, e.g. limiting a user's memory use to 1G only makes sense on a specific
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system that has more than 1G of memory. Each object inside the `perMachine`
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array comes with a `matchMachineId` or `matchHostname` field which indicate
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which systems to apply the listed settings to. Note that many fields
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accepted in the `perMachine` section can also be set at the top level (the
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`regular` section), where they define the fallback if no matching object in
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`perMachine` is found.
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4. Various fields are located in the `binding` section (a sub-sub-object of the
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user record; an intermediary object is inserted which is keyed by the
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machine ID of the host). Fields included in this section "bind" the object
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to a specific system. They generally include non-portable information about
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paths or UID assignments, that are true on a specific system, but not
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necessarily on others, and which are managed automatically by some user
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record manager (such as `systemd-homed`). Data in this section is considered
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part of the user record only in the local context, and is generally not
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ported to other systems. Due to that it is not included in the reduced user
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record the cryptographic signature defined in the `signature` section is
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calculated on. In `systemd-homed` this section is also removed when the
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user's record is stored in the `~/.identity` file in the home directory, so
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that every system with access to the home directory can manage these
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`binding` fields individually. Typically, the binding section is persisted
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to the local disk.
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5. Various fields are located in the `status` section (a sub-sub-object of the
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user record, also with an intermediary object between that is keyed by the
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machine ID, similar to the way the `binding` section is organized). This
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section is augmented during runtime only, and never persisted to disk. The
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idea is that this section contains information about current runtime
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resource usage (for example: currently used disk space of the user), that
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changes dynamically but is otherwise immediately associated with the user
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record and for many purposes should be considered to be part of the user
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record.
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6. The `signature` section contains one or more cryptographic signatures of a
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reduced version of the user record. This is used to ensure that only user
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records defined by a specific source are accepted on a system, by validating
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the signature against the set of locally accepted signature public keys. The
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signature is calculated from the JSON user record with all sections removed,
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except for `regular`, `privileged`, `perMachine`. Specifically, `binding`,
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`status`, `signature` itself and `secret` are removed first and thus not
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covered by the signature. This section is optional, and is only used when
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cryptographic validation of user records is required (as it is by
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`systemd-homed.service` for example).
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7. The `secret` section contains secret user credentials, such as password or
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PIN information. This data is never persisted, and never returned when user
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records are inquired by a client, privileged or not. This data should only
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be included in a user record very briefly, for example when certain very
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specific operations are executed. For example, in tools such as
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`systemd-homed` this section may be included in user records, when creating
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a new home directory, as passwords and similar credentials need to be
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provided to encrypt the home directory with.
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Here's a tabular overview of the sections and their properties:
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| Section | Included in Signature | Persistent | Security Sensitive | Contains Host-Specific Data |
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|------------|-----------------------|------------|--------------------|-----------------------------|
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| regular | yes | yes | no | no |
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| privileged | yes | yes | yes | no |
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| perMachine | yes | yes | no | yes |
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| binding | no | yes | no | yes |
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| status | no | no | no | yes |
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| signature | no | yes | no | no |
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| secret | no | no | yes | no |
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Note that services providing user records to the local system are free to
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manage only a subset of these sections and never include the others in
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them. For example, a service that has no concept of signed records (for example
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because the records it manages are inherently trusted anyway) does not have to
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bother with the `signature` section. A service that only defines records in a
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strictly local context and without signatures doesn't have to deal with the
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`perMachine` or `binding` sections and can include its data exclusively in the
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regular section. A service that uses a separate, private channel for
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authenticating users (or that doesn't have a concept of authentication at all)
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does not need to be concerned with the `secret` section of user records, as
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the fields included therein are only useful when executing authentication
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operations natively against JSON user records.
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The `systemd-homed` manager uses all seven sections for various
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purposes. Inside the home directories (and if the LUKS2 backend is used, also
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in the LUKS2 header) a user record containing the `regular`, `privileged`,
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`perMachine` and `signature` sections is stored. `systemd-homed` also stores a
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version of the record on the host, with the same four sections and augmented
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with an additional, fifth `binding` section. When a local client enquires about
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a user record managed by `systemd-homed` the service will add in some
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additional information about the user and home directory in the `status`
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section — this version is only transferred via IPC and never written to
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disk. Finally the `secret` section is used during authentication operations via
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IPC to transfer the user record along with its authentication tokens in one go.
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## Fields in the `regular` section
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As mentioned, the `regular` section's fields are placed at the top level
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object. The following fields are currently defined:
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`userName` → The UNIX user name for this record. Takes a string with a valid
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UNIX user name. This field is the only mandatory field, all others are
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optional. Corresponds with the `pw_name` field of of `struct passwd` and the
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`sp_namp` field of `struct spwd` (i.e. the shadow user record stored in
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`/etc/shadow`). See [User/Group Name Syntax](https://systemd.io/USER_NAMES) for
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the (relaxed) rules the various systemd components enforce on user/group names.
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`realm` → The "realm" a user is defined in. This concept allows distinguishing
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users with the same name that originate in different organizations or
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installations. This should take a string in DNS domain syntax, but doesn't have
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to refer to an actual DNS domain (though it is recommended to use one for
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this). The idea is that the user `lpoetter` in the `redhat.com` realm might be
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distinct from the same user in the `poettering.hq` realm. User records for the
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same user name that have different realm fields are considered referring to
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different users. When updating a user record it is required that any new
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version has to match in both `userName` and `realm` field. This field is
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optional, when unset the user should not be considered part of any realm. A
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user record with a realm set is never compatible (for the purpose of updates,
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see above) with a user record without one set, even if the `userName` field matches.
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`realName` → The real name of the user, a string. This should contain the
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user's real ("human") name, and corresponds loosely to the GECOS field of
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classic UNIX user records. When converting a `struct passwd` to a JSON user
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record this field is initialized from GECOS (i.e. the `pw_gecos` field), and
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vice versa when converting back. That said, unlike GECOS this field is supposed
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to contain only the real name and no other information. This field must not
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contain control characters (such as `\n`) or colons (`:`), since those are used
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as record separators in classic `/etc/passwd` files and similar formats.
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`emailAddress` → The email address of the user, formatted as
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string. [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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initializes the `$EMAIL` environment variable from this value for all login
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sessions.
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`iconName` → The name of an icon picked by the user, for example for the
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purpose of an avatar. This must be a string, and should follow the semantics
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defined in the [Icon Naming
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Specification](https://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html).
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`location` → A free-form location string describing the location of the user,
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if that is applicable. It's probably wise to use a location string processable
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by geo-location subsystems, but this is not enforced nor required. Example:
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`Berlin, Germany` or `Basement, Room 3a`.
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`disposition` → A string, one of `intrinsic`, `system`, `dynamic`, `regular`,
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`container`, `reserved`. If specified clarifies the disposition of the user,
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i.e. the context it is defined in. For regular, "human" users this should be
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`regular`, for system users (i.e. users that system services run under, and
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similar) this should be `system`. The `intrinsic` disposition should be used
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only for the two users that have special meaning to the OS kernel itself,
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i.e. the `root` and `nobody` users. The `container` string should be used for
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users that are used by an OS container, and hence will show up in `ps` listings
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and such, but are only defined in container context. Finally `reserved` should
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be used for any users outside of these use-cases. Note that this property is
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entirely optional and applications are assumed to be able to derive the
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disposition of a user automatically from a record even in absence of this
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field, based on other fields, for example the numeric UID. By setting this
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field explicitly applications can override this default determination.
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`lastChangeUSec` → An unsigned 64bit integer value, referring to a timestamp in µs
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since the epoch 1970, indicating when the user record (specifically, any of the
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`regular`, `privileged`, `perMachine` sections) was last changed. This field is
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used when comparing two records of the same user to identify the newer one, and
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is used for example for automatic updating of user records, where appropriate.
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`lastPasswordChangeUSec` → Similar, also an unsigned 64bit integer value,
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indicating the point in time the password (or any authentication token) of the
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user was last changed. This corresponds to the `sp_lstchg` field of `struct
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spwd`, i.e. the matching field in the user shadow database `/etc/shadow`,
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though provides finer resolution.
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`shell` → A string, referring to the shell binary to use for terminal logins of
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this user. This corresponds with the `pw_shell` field of `struct passwd`, and
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should contain an absolute file system path. For system users not suitable for
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terminal log-in this field should not be set.
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`umask` → The `umask` to set for the user's login sessions. Takes an
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integer. Note that usually on UNIX the umask is noted in octal, but JSON's
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integers are generally written in decimal, hence in this context we denote it
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umask in decimal too. The specified value should be in the valid range for
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umasks, i.e. 0000…0777 (in octal as typical in UNIX), or 0…511 (in decimal, how
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it actually appears in the JSON record). This `umask` is automatically set by
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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for all login sessions of the user.
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`environment` → An array of strings, each containing an environment variable
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and its value to set for the user's login session, in a format compatible with
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[`putenv()`](http://man7.org/linux/man-pages/man3/putenv.3.html). Any
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environment variable listed here is automatically set by
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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for all login sessions of the user.
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`timeZone` → A string indicating a preferred timezone to use for the user. When
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logging in
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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will automatically initialize the `$TZ` environment variable from this
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string. The string should be a `tzdata` compatible location string, for
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example: `Europe/Berlin`.
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`preferredLanguage` → A string indicating the preferred language/locale for the
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user. When logging in
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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will automatically initialize the `$LANG` environment variable from this
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string. The string hence should be in a format compatible with this environment
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variable, for example: `de_DE.UTF8`.
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`niceLevel` → An integer value in the range -20…19. When logging in
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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will automatically initialize the login process' nice level to this value with,
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which is then inherited by all the user's processes, see
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[`setpriority()`](http://man7.org/linux/man-pages/man2/setpriority.2.html) for
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more information.
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`resourceLimits` → An object, where each key refers to a Linux resource limit
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(such as `RLIMIT_NOFILE` and similar). Their values should be an object with
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two keys `cur` and `max` for the soft and hard resource limit. When logging in
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[`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
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will automatically initialize the login process' resource limits to these
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values, which is then inherited by all the user's processes, see
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[`setrlimit()`](http://man7.org/linux/man-pages/man2/setrlimit.2.html) for more
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information.
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`locked` → A boolean value. If true the user account is locked, the user may
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not log in. If this field is missing it should be assumed to be false,
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i.e. logins are permitted. This field corresponds to the `sp_expire` field of
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`struct spwd` (i.e. the `/etc/shadow` data for a user) being set to zero or
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one.
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`notBeforeUSec` → An unsigned 64bit integer value, indicating a time in µs since
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the UNIX epoch (1970) before which the record should be considered invalid for
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the purpose of logging in.
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`notAfterUSec` → Similar, but indicates the point in time *after* which logins
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shall not be permitted anymore. This corresponds to the `sp_expire` field of
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`struct spwd`, when it is set to a value larger than one, but provides finer
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granularity.
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`storage` → A string, one of `classic`, `luks`, `directory`, `subvolume`,
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`fscrypt`, `cifs`. Indicates the storage mechanism for the user's home
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directory. If `classic` the home directory is a plain directory as in classic
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UNIX. When `directory`, the home directory is a regular directory, but the
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`~/.identity` file in it contains the user's user record, so that the directory
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is self-contained. Similar, `subvolume` is a `btrfs` subvolume that also
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contains a `~/.identity` user record; `fscrypt` is an `fscrypt`-encrypted
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directory, also containing the `~/.identity` user record; `luks` is a per-user
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LUKS volume that is mounted as home directory, and `cifs` a home directory
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mounted from a Windows File Share. The five latter types are primarily used by
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`systemd-homed` when managing home directories, but may be used if other
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managers are used too. If this is not set `classic` is the implied default.
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`diskSize` → An unsigned 64bit integer, indicating the intended home directory
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disk space in bytes to assign to the user. Depending on the selected storage
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type this might be implement differently: for `luks` this is the intended size
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of the file system and LUKS volume, while for the others this likely translates
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to classic file system quota settings.
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`diskSizeRelative` → Similar to `diskSize` but takes a relative value, but
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specifies a fraction of the available disk space on the selected storage medium
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to assign to the user. This unsigned integer value is normalized to 2^32 =
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100%.
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`skeletonDirectory` → Takes a string with the absolute path to the skeleton
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directory to populate a new home directory from. This is only used when a home
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directory is first created, and defaults to `/etc/skel` if not defined.
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`accessMode` → Takes an unsigned integer in the range 0…511 indicating the UNIX
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access mask for the home directory when it is first created.
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`tasksMax` → Takes an unsigned 64bit integer indicating the maximum number of
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tasks the user may start in parallel during system runtime. This counts
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all tasks (i.e. threads, where each process is at least one thread) the user starts or that are
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forked from these processes even if the user identity is changed (for example
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by setuid binaries/`su`/`sudo` and similar).
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[`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html)
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enforces this by setting the `TasksMax` slice property for the user's slice
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`user-$UID.slice`.
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`memoryHigh`/`memoryMax` → These take unsigned 64bit integers indicating upper
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memory limits for all processes of the user (plus all processes forked off them
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that might have changed user identity), in bytes. Enforced by
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[`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html),
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similar to `tasksMax`.
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`cpuWeight`/`ioWeight` → These take unsigned integers in the range 1…10000
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(defaults to 100) and configure the CPU and IO scheduling weights for the
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user's processes as a whole. Also enforced by
|
|
[`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html),
|
|
similar to `tasksMax`, `memoryHigh` and `memoryMax`.
|
|
|
|
`mountNoDevices`/`mountNoSuid`/`mountNoExecute` → Three booleans that control
|
|
the `nodev`, `nosuid`, `noexec` mount flags of the user's home
|
|
directories. Note that these booleans are only honored if the home directory
|
|
is managed by a subsystem such as `systemd-homed.service` that automatically
|
|
mounts home directories on login.
|
|
|
|
`cifsDomain` → A string indicating the Windows File Sharing domain (CIFS) to
|
|
use. This is generally useful, but particularly when `cifs` is used as storage
|
|
mechanism for the user's home directory, see above.
|
|
|
|
`cifsUserName` → A string indicating the Windows File Sharing user name (CIFS)
|
|
to associate this user record with. This is generally useful, but particularly
|
|
useful when `cifs` is used as storage mechanism for the user's home directory,
|
|
see above.
|
|
|
|
`cifsService` → A string indicating the Windows File Share service (CIFS) to
|
|
mount as home directory of the user on login.
|
|
|
|
`imagePath` → A string with an absolute file system path to the file, directory
|
|
or block device to use for storage backing the home directory. If the `luks`
|
|
storage is used this refers to the loopback file or block device node to store
|
|
the LUKS volume on. For `fscrypt`, `directory`, `subvolume` this refers to the
|
|
directory to bind mount as home directory on login. Not defined for `classic`
|
|
or `cifs`.
|
|
|
|
`homeDirectory` → A string with an absolute file system path to the home
|
|
directory. This is where the image indicated in `imagePath` is mounted to on
|
|
login and thus indicates the application facing home directory while the home
|
|
directory is active, and is what the user's `$HOME` environment variable is set
|
|
to during log-in. It corresponds to the `pw_dir` field of `struct passwd`.
|
|
|
|
`uid` → An unsigned integer in the range 0…4294967295: the numeric UNIX user ID (UID) to
|
|
use for the user. This corresponds to the `pw_uid` field of `struct passwd`.
|
|
|
|
`gid` → An unsigned integer in the range 0…4294967295: the numeric UNIX group
|
|
ID (GID) to use for the user. This corresponds to the `pw_gid` field of
|
|
`struct passwd`.
|
|
|
|
`memberOf` → An array of strings, each indicating a UNIX group this user shall
|
|
be a member of. The listed strings must be valid group names, but it is not
|
|
required that all groups listed exist in all contexts: any entry for which no
|
|
group exists should be silently ignored.
|
|
|
|
`fileSystemType` → A string, one of `ext4`, `xfs`, `btrfs` (possibly others) to
|
|
use as file system for the user's home directory. This is primarily relevant
|
|
when the storage mechanism used is `luks` as a file system to use inside the
|
|
LUKS container must be selected.
|
|
|
|
`partitionUuid` → A string containing a lower-case, text-formatted UUID, referencing
|
|
the GPT partition UUID the home directory is located in. This is primarily
|
|
relevant when the storage mechanism used is `luks`.
|
|
|
|
`luksUuid` → A string containing a lower-case, text-formatted UUID, referencing
|
|
the LUKS volume UUID the home directory is located in. This is primarily
|
|
relevant when the storage mechanism used is `luks`.
|
|
|
|
`fileSystemUuid` → A string containing a lower-case, text-formatted UUID,
|
|
referencing the file system UUID the home directory is located in. This is
|
|
primarily relevant when the storage mechanism used is `luks`.
|
|
|
|
`luksDiscard` → A boolean. If true and `luks` storage is used controls whether
|
|
the loopback block devices, LUKS and the file system on top shall be used in
|
|
`discard` mode, i.e. erased sectors should always be returned to the underlying
|
|
storage. If false and `luks` storage is used turns this behavior off. In
|
|
addition, depending on this setting an `FITRIM` or `fallocate()` operation is
|
|
executed to make sure the image matches the selected option.
|
|
|
|
`luksOfflineDiscard` → A boolean. Similar to `luksDiscard`, it controls whether
|
|
to trim/allocate the file system/backing file when deactivating the home
|
|
directory.
|
|
|
|
`luksCipher` → A string, indicating the cipher to use for the LUKS storage mechanism.
|
|
|
|
`luksCipherMode` → A string, selecting the cipher mode to use for the LUKS storage mechanism.
|
|
|
|
`luksVolumeKeySize` → An unsigned integer, indicating the volume key length in
|
|
bytes to use for the LUKS storage mechanism.
|
|
|
|
`luksPbkdfHashAlgorithm` → A string, selecting the hash algorithm to use for
|
|
the PBKDF operation for the LUKS storage mechanism.
|
|
|
|
`luksPbkdfType` → A string, indicating the PBKDF type to use for the LUKS storage mechanism.
|
|
|
|
`luksPbkdfTimeCostUSec` → An unsigned 64bit integer, indicating the intended
|
|
time cost for the PBKDF operation, when the LUKS storage mechanism is used, in
|
|
µs.
|
|
|
|
`luksPbkdfMemoryCost` → An unsigned 64bit integer, indicating the intended
|
|
memory cost for the PBKDF operation, when LUKS storage is used, in bytes.
|
|
|
|
`luksPbkdfParallelThreads` → An unsigned 64bit integer, indicating the intended
|
|
required parallel threads for the PBKDF operation, when LUKS storage is used.
|
|
|
|
`service` → A string declaring the service that defines or manages this user
|
|
record. It is recommended to use reverse domain name notation for this. For
|
|
example, if `systemd-homed` manages a user a string of `io.systemd.Home` is
|
|
used for this.
|
|
|
|
`rateLimitIntervalUSec` → An unsigned 64bit integer that configures the
|
|
authentication rate limiting enforced on the user account. This specifies a
|
|
timer interval (in µs) within which to count authentication attempts. When the
|
|
counter goes above the value configured n `rateLimitIntervalBurst` log-ins are
|
|
temporarily refused until the interval passes.
|
|
|
|
`rateLimitIntervalBurst` → An unsigned 64bit integer, closely related to
|
|
`rateLimitIntervalUSec`, that puts a limit on authentication attempts within
|
|
the configured time interval.
|
|
|
|
`enforcePasswordPolicy` → A boolean. Configures whether to enforce the system's
|
|
password policy when creating the home directory for the user or changing the
|
|
user's password. By default the policy is enforced, but if this field is false
|
|
it is bypassed.
|
|
|
|
`autoLogin` → A boolean. If true the user record is marked as suitable for
|
|
auto-login. Systems are supposed to automatically log in a user marked this way
|
|
during boot, if there's exactly one user on it defined this way.
|
|
|
|
`stopDelayUSec` → An unsigned 64bit integer, indicating the time in µs the
|
|
per-user service manager is kept around after the user fully logged out. This
|
|
value is honored by
|
|
[`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html). If
|
|
set to zero the per-user service manager is immediately terminated when the
|
|
user logs out, and longer values optimize high-frequency log-ins as the
|
|
necessary work to set up and tear down a log-in is reduced if the service
|
|
manager stays running.
|
|
|
|
`killProcesses` → A boolean. If true all processes of the user are
|
|
automatically killed when the user logs out. This is enforced by
|
|
[`systemd-logind.service`](https://www.freedesktop.org/software/systemd/man/systemd-logind.service.html). If
|
|
false any processes left around when the user logs out are left running.
|
|
|
|
`passwordChangeMinUSec`/`passwordChangeMaxUSec` → An unsigned 64bit integer,
|
|
encoding how much time has to pass at least/at most between password changes of
|
|
the user. This corresponds with the `sp_min` and `sp_max` fields of `struct
|
|
spwd` (i.e. the `/etc/shadow` entries of the user), but offers finer
|
|
granularity.
|
|
|
|
`passwordChangeWarnUSec` → An unsigned 64bit integer, encoding how much time to
|
|
warn the user before their password expires, in µs. This corresponds with the
|
|
`sp_warn` field of `struct spwd`.
|
|
|
|
`passwordChangeInactiveUSec` → An unsigned 64bit integer, encoding how much
|
|
time has to pass after the password expired that the account is
|
|
deactivated. This corresponds with the `sp_inact` field of `struct spwd`.
|
|
|
|
`passwordChangeNow` → A boolean. If true the user has to change their password
|
|
on next login. This corresponds with the `sp_lstchg` field of `struct spwd`
|
|
being set to zero.
|
|
|
|
`pkcs11TokenUri` → An array of strings, each with an RFC 7512 compliant PKCS#11
|
|
URI referring to security token (or smart card) of some form, that shall be
|
|
associated with the user and may be used for authentication. The URI is used to
|
|
search for an X.509 certificate and associated private key that may be used to
|
|
decrypt an encrypted secret key that is used to unlock the user's account (see
|
|
below). It's undefined how precise the URI is: during log-in it is tested
|
|
against all plugged in security tokens and if there's exactly one matching
|
|
private key found with it it is used.
|
|
|
|
`fido2HmacCredential` → An array of strings, each with a Base64-encoded FIDO2
|
|
credential ID that shell be used for authentication with FIDO2 devices that
|
|
implement the `hmac-secret` extension. The salt to pass to the FIDO2 device is
|
|
found in `fido2HmacSalt`.
|
|
|
|
`recoveryKeyType` → An array of strings, each indicating the type of one
|
|
recovery key. The only supported recovery key type at the moment is `modhex64`,
|
|
for details see the description of `recoveryKey` below. An account may have any
|
|
number of recovery keys defined, and the array should have one entry for each.
|
|
|
|
`privileged` → An object, which contains the fields of the `privileged` section
|
|
of the user record, see below.
|
|
|
|
`perMachine` → An array of objects, which contain the `perMachine` section of
|
|
the user record, and thus fields to apply on specific systems only, see below.
|
|
|
|
`binding` → An object, keyed by machine IDs formatted as strings, pointing
|
|
to objects that contain the `binding` section of the user record,
|
|
i.e. additional fields that bind the user record to a specific machine, see
|
|
below.
|
|
|
|
`status` → An object, keyed by machine IDs formatted as strings, pointing to
|
|
objects that contain the `status` section of the user record, i.e. additional
|
|
runtime fields that expose the current status of the user record on a specific
|
|
system, see below.
|
|
|
|
`signature` → An array of objects, which contain cryptographic signatures of
|
|
the user record, i.e. the fields of the `signature` section of the user record,
|
|
see below.
|
|
|
|
`secret` → An object, which contains the fields of the `secret` section of the
|
|
user record, see below.
|
|
|
|
## Fields in the `privileged` section
|
|
|
|
As mentioned, the `privileged` section is encoded in a sub-object of the user
|
|
record top-level object, in the `privileged` field. Any data included in this
|
|
object shall only be visible to the administrator and the user themselves, and
|
|
be suppressed implicitly when other users get access to a user record. It thus
|
|
takes the role of the `/etc/shadow` records for each user, which has similarly
|
|
restrictive access semantics. The following fields are currently defined:
|
|
|
|
`passwordHint` → A user-selected password hint in free-form text. This should
|
|
be a string like "What's the name of your first pet?", but is entirely for the
|
|
user to choose.
|
|
|
|
`hashedPassword` → An array of strings, each containing a hashed UNIX password
|
|
string, in the format
|
|
[`crypt(3)`](http://man7.org/linux/man-pages/man3/crypt.3.html) generates. This
|
|
corresponds with `sp_pwdp` field of `struct spwd` (and in a way the `pw_passwd`
|
|
field of `struct passwd`).
|
|
|
|
`sshAuthorizedKeys` → An array of strings, each listing an SSH public key that
|
|
is authorized to access the account. The strings should follow the same format
|
|
as the lines in the traditional `~/.ssh/authorized_key` file.
|
|
|
|
`pkcs11EncryptedKey` → An array of objects. Each element of the array should be
|
|
an object consisting of three string fields: `uri` shall contain a PKCS#11
|
|
security token URI, `data` shall contain a Base64-encoded encrypted key and
|
|
`hashedPassword` shall contain a UNIX password hash to test the key
|
|
against. Authenticating with a security token against this account shall work
|
|
as follows: the encrypted secret key is converted from its Base64
|
|
representation into binary, then decrypted with the PKCS#11 `C_Decrypt()`
|
|
function of the PKCS#11 module referenced by the specified URI, using the
|
|
private key found on the same token. The resulting decrypted key is then
|
|
Base64-encoded and tested against the specified UNIX hashed password. The
|
|
Base64-encoded decrypted key may also be used to unlock further resources
|
|
during log-in, for example the LUKS or `fscrypt` storage backend. It is
|
|
generally recommended that for each entry in `pkcs11EncryptedKey` there's also
|
|
a matching one in `pkcs11TokenUri` and vice versa, with the same URI, appearing
|
|
in the same order, but this should not be required by applications processing
|
|
user records.
|
|
|
|
`fido2HmacSalt` → An array of objects, implementing authentication support with
|
|
FIDO2 devices that implement the `hmac-secret` extension. Each element of the
|
|
array should be an object consisting of three string fields: `credential`,
|
|
`salt`, `hashedPassword`. The first two shall contain Base64-encoded binary
|
|
data: the FIDO2 credential ID and the salt value to pass to the FIDO2
|
|
device. During authentication this salt along with the credential ID is sent to
|
|
the FIDO2 token, which will HMAC hash the salt with its internal secret key and
|
|
return the result. This resulting binary key should then be Base64-encoded and
|
|
used as string password for the further layers of the stack. The
|
|
`hashedPassword` field of the `fido2HmacSalt` field shall be a UNIX password
|
|
hash to test this derived secret key against for authentication. It is
|
|
generally recommended that for each entry in `fido2HmacSalt` there's also a
|
|
matching one in `fido2HmacCredential`, and vice versa, with the same credential
|
|
ID, appearing in the same order, but this should not be required by
|
|
applications processing user records.
|
|
|
|
`recoveryKey`→ An array of objects, each defining a recovery key. The object
|
|
has two mandatory fields: `type` indicates the type of recovery key. The only
|
|
currently permitted value is the string `modhex64`. The `hashedPassword` field
|
|
contains a UNIX password hash of the normalized recovery key. Recovery keys are
|
|
in most ways similar to regular passwords, except that they are generated by
|
|
the computer, not chosen by the user, and are longer. Currently, the only
|
|
supported recovery key format is `modhex64`, which consists of 64
|
|
[modhex](https://developers.yubico.com/yubico-c/Manuals/modhex.1.html)
|
|
characters (i.e. 256bit of information), in groups of 8 chars separated by
|
|
dashes,
|
|
e.g. `lhkbicdj-trbuftjv-tviijfck-dfvbknrh-uiulbhui-higltier-kecfhkbk-egrirkui`. Recovery
|
|
keys should be accepted wherever regular passwords are. The `recoveryKey` field
|
|
should always be accompanied by a `recoveryKeyType` field (see above), and each
|
|
entry in either should map 1:1 to an entry in the other, in the same order and
|
|
matching the type. When accepting a recovery key it should be brought
|
|
automatically into normalized form, i.e. the dashes inserted when missing, and
|
|
converted into lowercase before tested against the UNIX password hash, so that
|
|
recovery keys are effectively case-insensitive.
|
|
|
|
## Fields in the `perMachine` section
|
|
|
|
As mentioned, the `perMachine` section contains settings that shall apply to
|
|
specific systems only. This is primarily interesting for resource management
|
|
properties as they tend to require a per-system focus, however they may be used
|
|
for other purposes too.
|
|
|
|
The `perMachine` field in the top-level object is an array of objects. When
|
|
processing the user record first the various fields on the top-level object
|
|
should be used. Then this array should be iterated in order, and the various
|
|
settings be applied that match either the indicated machine ID or host
|
|
name. There may be multiple array entries that match a specific system, in
|
|
which case all the object's setting should be applied. If the same option is
|
|
set in the top-level object as in a per-machine object the latter wins and
|
|
entirely undoes the setting in the top-level object (i.e. no merging of
|
|
properties that are arrays themselves is done). If the same option is set in
|
|
multiple per-machine objects the one specified later in the array wins (and
|
|
here too no merging of individual fields is done, the later field always wins
|
|
in full).
|
|
|
|
The following fields are defined in this section:
|
|
|
|
`matchMachineId` → An array of strings with each a formatted 128bit ID in
|
|
hex. If any of the specified IDs match the system's local machine ID
|
|
(i.e. matches `/etc/machine-id`) the fields in this object are honored.
|
|
|
|
`matchHostname` → An array of string with a each a valid hostname. If any of
|
|
the specified hostnames match the system's local hostname, the fields in this
|
|
object are honored. If both `matchHostname` and `matchMachineId` are used
|
|
within the same array entry, the object is honored when either match succeeds,
|
|
i.e. the two match types are combined in OR, not in AND.
|
|
|
|
These two are the only two fields specific to this section. All other fields
|
|
that may be used in this section are identical to the equally named ones in the
|
|
`regular` section (i.e. at the top-level object). Specifically, these are:
|
|
|
|
`iconName`, `location`, `shell`, `umask`, `environment`, `timeZone`,
|
|
`preferredLanguage`, `niceLevel`, `resourceLimits`, `locked`, `notBeforeUSec`,
|
|
`notAfterUSec`, `storage`, `diskSize`, `diskSizeRelative`, `skeletonDirectory`,
|
|
`accessMode`, `tasksMax`, `memoryHigh`, `memoryMax`, `cpuWeight`, `ioWeight`,
|
|
`mountNoDevices`, `mountNoSuid`, `mountNoExecute`, `cifsDomain`,
|
|
`cifsUserName`, `cifsService`, `imagePath`, `uid`, `gid`, `memberOf`,
|
|
`fileSystemType`, `partitionUuid`, `luksUuid`, `fileSystemUuid`, `luksDiscard`,
|
|
`luksOfflineDiscard`, `luksCipher`, `luksCipherMode`, `luksVolumeKeySize`,
|
|
`luksPbkdfHashAlgorithm`, `luksPbkdfType`, `luksPbkdfTimeCostUSec`,
|
|
`luksPbkdfMemoryCost`, `luksPbkdfParallelThreads`, `rateLimitIntervalUSec`,
|
|
`rateLimitBurst`, `enforcePasswordPolicy`, `autoLogin`, `stopDelayUSec`,
|
|
`killProcesses`, `passwordChangeMinUSec`, `passwordChangeMaxUSec`,
|
|
`passwordChangeWarnUSec`, `passwordChangeInactiveUSec`, `passwordChangeNow`,
|
|
`pkcs11TokenUri`, `fido2HmacCredential`.
|
|
|
|
## Fields in the `binding` section
|
|
|
|
As mentioned, the `binding` section contains additional fields about the user
|
|
record, that bind it to the local system. These fields are generally used by a
|
|
local user manager (such as `systemd-homed.service`) to add in fields that make
|
|
sense in a local context but not necessarily in a global one. For example, a
|
|
user record that contains no `uid` field in the regular section is likely
|
|
extended with one in the `binding` section to assign a local UID if no global
|
|
UID is defined.
|
|
|
|
All fields in the `binding` section only make sense in a local context and are
|
|
suppressed when the user record is ported between systems. The `binding` section
|
|
is generally persisted on the system but not in the home directories themselves
|
|
and the home directory is supposed to be fully portable and thus not contain
|
|
the information that `binding` is supposed to contain that binds the portable
|
|
record to a specific system.
|
|
|
|
The `binding` sub-object on the top-level user record object is keyed by the
|
|
machine ID the binding is intended for, which point to an object with the
|
|
fields of the bindings. These fields generally match fields that may also be
|
|
defined in the `regular` and `perMachine` sections, however override
|
|
both. Usually, the `binding` value should not contain settings different from
|
|
those set via `regular` or `perMachine`, however this might happen if some
|
|
settings are not supported locally (think: `fscrypt` is recorded as intended
|
|
storage mechanism in the `regular` section, but the local kernel does not
|
|
support `fscrypt`, hence `directory` was chosen as implicit fallback), or have
|
|
been changed in the `regular` section through updates (e.g. a home directory
|
|
was created with `luks` as storage mechanism but later the user record was
|
|
updated to prefer `subvolume`, which however doesn't change the actual storage
|
|
used already which is pinned in the `binding` section).
|
|
|
|
The following fields are defined in the `binding` section. They all have an
|
|
identical format and override their equally named counterparts in the `regular`
|
|
and `perMachine` sections:
|
|
|
|
`imagePath`, `homeDirectory`, `partitionUuid`, `luksUuid`, `fileSystemUuid`,
|
|
`uid`, `gid`, `storage`, `fileSystemType`, `luksCipher`, `luksCipherMode`,
|
|
`luksVolumeKeySize`.
|
|
|
|
## Fields in the `status` section
|
|
|
|
As mentioned, the `status` section contains additional fields about the user
|
|
record that are exclusively acquired during runtime, and that expose runtime
|
|
metrics of the user and similar metadata that shall not be persisted but are
|
|
only acquired "on-the-fly" when requested.
|
|
|
|
This section is arranged similarly to the `binding` section: the `status`
|
|
sub-object of the top-level user record object is keyed by the machine ID,
|
|
which points to the object with the fields defined here. The following fields
|
|
are defined:
|
|
|
|
`diskUsage` → An unsigned 64bit integer. The currently used disk space of the
|
|
home directory in bytes. This value might be determined in different ways,
|
|
depending on the selected storage mechanism. For LUKS storage this is the file
|
|
size of the loopback file or block device size. For the
|
|
directory/subvolume/fscrypt storage this is the current disk space used as
|
|
reported by the file system quota subsystem.
|
|
|
|
`diskFree` → An unsigned 64bit integer, denoting the number of "free" bytes in
|
|
the disk space allotment, i.e. usually the difference between the disk size as
|
|
reported by `diskSize` and the used already as reported in `diskFree`, but
|
|
possibly skewed by metadata sizes, disk compression and similar.
|
|
|
|
`diskSize` → An unsigned 64bit integer, denoting the disk space currently
|
|
allotted to the user, in bytes. Depending on the storage mechanism this can mean
|
|
different things (see above). In contrast to the top-level field of the same
|
|
(or the one in the `perMachine` section), this field reports the current size
|
|
allotted to the user, not the intended one. The values may differ when user
|
|
records are updated without the home directory being re-sized.
|
|
|
|
`diskCeiling`/`diskFloor` → Unsigned 64bit integers indicating upper and lower
|
|
bounds when changing the `diskSize` value, in bytes. These values are typically
|
|
derived from the underlying data storage, and indicate in which range the home
|
|
directory may be re-sized in, i.e. in which sensible range the `diskSize` value
|
|
should be kept.
|
|
|
|
`state` → A string indicating the current state of the home directory. The
|
|
precise set of values exposed here are up to the service managing the home
|
|
directory to define (i.e. are up to the service identified with the `service`
|
|
field below). However, it is recommended to stick to a basic vocabulary here:
|
|
`inactive` for a home directory currently not mounted, `absent` for a home
|
|
directory that cannot be mounted currently because it does not exist on the
|
|
local system, `active` for a home directory that is currently mounted and
|
|
accessible.
|
|
|
|
`service` → A string identifying the service that manages this user record. For
|
|
example `systemd-homed.service` sets this to `io.systemd.Home` to all user
|
|
records it manages. This is particularly relevant to define clearly the context
|
|
in which `state` lives, see above. Note that this field also exists on the
|
|
top-level object (i.e. in the `regular` section), which it overrides. The
|
|
`regular` field should be used if conceptually the user record can only be
|
|
managed by the specified service, and this `status` field if it can
|
|
conceptually be managed by different managers, but currently is managed by the
|
|
specified one.
|
|
|
|
`signedLocally` → A boolean. If true indicates that the user record is signed
|
|
by a public key for which the private key is available locally. This means that
|
|
the user record may be modified locally as it can be re-signed with the private
|
|
key. If false indicates that the user record is signed by a public key
|
|
recognized by the local manager but whose private key is not available
|
|
locally. This means the user record cannot be modified locally as it couldn't
|
|
be signed afterwards.
|
|
|
|
`goodAuthenticationCounter` → An unsigned 64bit integer. This counter is
|
|
increased by one on every successful authentication attempt, i.e. an
|
|
authentication attempt where a security token of some form was presented and it
|
|
was correct.
|
|
|
|
`badAuthenticationCounter` → An unsigned 64bit integer. This counter is
|
|
increased by one on every unsuccessfully authentication attempt, i.e. an
|
|
authentication attempt where a security token of some form was presented and it
|
|
was incorrect.
|
|
|
|
`lastGoodAuthenticationUSec` → An unsigned 64bit integer, indicating the time
|
|
of the last successful authentication attempt in µs since the UNIX epoch (1970).
|
|
|
|
`lastBadAuthenticationUSec` → Similar, but the timestamp of the last
|
|
unsuccessfully authentication attempt.
|
|
|
|
`rateLimitBeginUSec` → An unsigned 64bit integer: the µs timestamp since the
|
|
UNIX epoch (1970) where the most recent rate limiting interval has been
|
|
started, as configured with `rateLimitIntervalUSec`.
|
|
|
|
`rateLimitCount` → An unsigned 64bit integer, counting the authentication
|
|
attempts in the current rate limiting interval, see above. If this counter
|
|
grows beyond the value configured in `rateLimitBurst` authentication attempts
|
|
are temporarily refused.
|
|
|
|
`removable` → A boolean value. If true the manager of this user record
|
|
determined the home directory being on removable media. If false it was
|
|
determined the home directory is in internal built-in media. (This is used by
|
|
`systemd-logind.service` to automatically pick the right default value for
|
|
`stopDelayUSec` if the field is not explicitly specified: for home directories
|
|
on removable media the delay is selected very low to minimize the chance the
|
|
home directory remains in unclean state if the storage device is removed from
|
|
the system by the user).
|
|
|
|
## Fields in the `signature` section
|
|
|
|
As mentioned, the `signature` section of the user record may contain one or
|
|
more cryptographic signatures of the user record. Like all others, this section
|
|
is optional, and only used when cryptographic validation of user records shall
|
|
be used. Specifically, all user records managed by `systemd-homed.service` will
|
|
carry such signatures and the service refuses managing user records that come
|
|
without signature or with signatures not recognized by any locally defined
|
|
public key.
|
|
|
|
The `signature` field in the top-level user record object is an array of
|
|
objects. Each object encapsulates one signature and has two fields: `data` and
|
|
`key` (both are strings). The `data` field contains the actual signature,
|
|
encoded in Base64, the `key` field contains a copy of the public key whose
|
|
private key was used to make the signature, in PEM format. Currently only
|
|
signatures with Ed25519 keys are defined.
|
|
|
|
Before signing the user record should be brought into "normalized" form,
|
|
i.e. the keys in all objects should be sorted alphabetically. All redundant
|
|
white-space and newlines should be removed and the JSON text then signed.
|
|
|
|
The signatures only cover the `regular`, `perMachine` and `privileged` sections
|
|
of the user records, all other sections (include `signature` itself), are
|
|
removed before the signature is calculated.
|
|
|
|
Rationale for signing and threat model: while a multi-user operating system
|
|
like Linux strives for being sufficiently secure even after a user acquired a
|
|
local login session reality tells us this is not the case. Hence it is
|
|
essential to restrict carefully which users may gain access to a system and
|
|
which ones shall not. A minimal level of trust must be established between
|
|
system, user record and the user themselves before a log-in request may be
|
|
permitted. In particular if the home directory is provided in its own LUKS2
|
|
encapsulated file system it is essential this trust is established before the
|
|
user logs in (and hence the file system mounted), since file system
|
|
implementations on Linux are well known to be relatively vulnerable to rogue
|
|
disk images. User records and home directories in many context are expected to
|
|
be something shareable between multiple systems, and the transfer between them
|
|
might not happen via exclusively trusted channels. Hence it's essential that
|
|
the user record is not manipulated between uses. Finally, resource management
|
|
(which may be done by the various fields of the user record) is security
|
|
sensitive, since it should forcefully lock the user into the assigned resource
|
|
usage and not allow them to use more. The requirement of being able to trust
|
|
the user record data combined with the potential transfer over untrusted
|
|
channels suggest a cryptographic signature mechanism where only user records
|
|
signed by a recognized key are permitted to log in locally.
|
|
|
|
Note that other mechanisms for establishing sufficient trust exist too, and are
|
|
perfectly valid as well. For example, systems like LDAP/ActiveDirectory
|
|
generally insist on user record transfer from trusted servers via encrypted TLS
|
|
channels only. Or traditional UNIX users created locally in `/etc/passwd` never
|
|
exist outside of the local trusted system, hence transfer and trust in the
|
|
source are not an issue. The major benefit of operating with signed user
|
|
records is that they are self-sufficiently trusted, not relying on a secure
|
|
channel for transfer, and thus being compatible with a more distributed model
|
|
of home directory transfer, including on USB sticks and such.
|
|
|
|
## Fields in the `secret` section
|
|
|
|
As mentioned, the `secret` section of the user record should never be persisted
|
|
nor transferred across machines. It is only defined in short-lived operations,
|
|
for example when a user record is first created or registered, as the secret
|
|
key data needs to be available to derive encryption keys from and similar.
|
|
|
|
The `secret` field of the top-level user record contains the following fields:
|
|
|
|
`password` → an array of strings, each containing a plain text password.
|
|
|
|
`tokenPin` → an array of strings, each containing a plain text PIN, suitable
|
|
for unlocking security tokens that require that. (The field `pkcs11Pin` should
|
|
be considered a compatibility alias for this field, and merged with `tokenPin`
|
|
in case both are set.)
|
|
|
|
`pkcs11ProtectedAuthenticationPathPermitted` → a boolean. If set to true allows
|
|
the receiver to use the PKCS#11 "protected authentication path" (i.e. a
|
|
physical button/touch element on the security token) for authenticating the
|
|
user. If false or unset, authentication this way shall not be attempted.
|
|
|
|
`fido2UserPresencePermitted` → a boolean. If set to true allows the receiver to
|
|
use the FIDO2 "user presence" flag. This is similar to the concept of
|
|
`pkcs11ProtectedAuthenticationPathPermitted`, but exposes the FIDO2 concept
|
|
behind it. If false or unset authentication this way shall not be attempted.
|
|
|
|
## Mapping to `struct passwd` and `struct spwd`
|
|
|
|
When mapping classic UNIX user records (i.e. `struct passwd` and `struct spwd`)
|
|
to JSON user records the following mappings should be applied:
|
|
|
|
| Structure | Field | Section | Field | Condition |
|
|
|-----------------|-------------|--------------|------------------------------|----------------------------|
|
|
| `struct passwd` | `pw_name` | `regular` | `userName` | |
|
|
| `struct passwd` | `pw_passwd` | `privileged` | `password` | (See notes below) |
|
|
| `struct passwd` | `pw_uid` | `regular` | `uid` | |
|
|
| `struct passwd` | `pw_gid` | `regular` | `gid` | |
|
|
| `struct passwd` | `pw_gecos` | `regular` | `realName` | |
|
|
| `struct passwd` | `pw_dir` | `regular` | `homeDirectory` | |
|
|
| `struct passwd` | `pw_shell` | `regular` | `shell` | |
|
|
| `struct spwd` | `sp_namp` | `regular` | `userName` | |
|
|
| `struct spwd` | `sp_pwdp` | `privileged` | `password` | (See notes below) |
|
|
| `struct spwd` | `sp_lstchg` | `regular` | `lastPasswordChangeUSec` | (if `sp_lstchg` > 0) |
|
|
| `struct spwd` | `sp_lstchg` | `regular` | `passwordChangeNow` | (if `sp_lstchg` == 0) |
|
|
| `struct spwd` | `sp_min` | `regular` | `passwordChangeMinUSec` | |
|
|
| `struct spwd` | `sp_max` | `regular` | `passwordChangeMaxUSec` | |
|
|
| `struct spwd` | `sp_warn` | `regular` | `passwordChangeWarnUSec` | |
|
|
| `struct spwd` | `sp_inact` | `regular` | `passwordChangeInactiveUSec` | |
|
|
| `struct spwd` | `sp_expire` | `regular` | `locked` | (if `sp_expire` in [0, 1]) |
|
|
| `struct spwd` | `sp_expire` | `regular` | `notAfterUSec` | (if `sp_expire` > 1) |
|
|
|
|
At this time almost all Linux machines employ shadow passwords, thus the
|
|
`pw_passwd` field in `struct passwd` is set to `"x"`, and the actual password
|
|
is stored in the shadow entry `struct spwd`'s field `sp_pwdp`.
|
|
|
|
## Extending These Records
|
|
|
|
User records following this specifications are supposed to be extendable for
|
|
various applications. In general, subsystems are free to introduce their own
|
|
keys, as long as:
|
|
|
|
* Care should be taken to place the keys in the right section, i.e. the most
|
|
appropriate for the data field.
|
|
|
|
* Care should be taken to avoid namespace clashes. Please prefix your fields
|
|
with a short identifier of your project to avoid ambiguities and
|
|
incompatibilities.
|
|
|
|
* This specification is supposed to be a living specification. If you need
|
|
additional fields, please consider submitting them upstream for inclusion in
|
|
this specification. If they are reasonably universally useful, it would be
|
|
best to list them here.
|
|
|
|
## Examples
|
|
|
|
The shortest valid user record looks like this:
|
|
|
|
```json
|
|
{
|
|
"userName" : "u"
|
|
}
|
|
```
|
|
|
|
A reasonable user record for a system user might look like this:
|
|
|
|
```json
|
|
{
|
|
"userName" : "httpd",
|
|
"uid" : 473,
|
|
"gid" : 473,
|
|
"disposition" : "system",
|
|
"locked" : true
|
|
}
|
|
```
|
|
|
|
A fully featured user record associated with a home directory managed by
|
|
`systemd-homed.service` might look like this:
|
|
|
|
```json
|
|
{
|
|
"autoLogin" : true,
|
|
"binding" : {
|
|
"15e19cf24e004b949ddaac60c74aa165" : {
|
|
"fileSystemType" : "ext4",
|
|
"fileSystemUuid" : "758e88c8-5851-4a2a-b88f-e7474279c111",
|
|
"gid" : 60232,
|
|
"homeDirectory" : "/home/grobie",
|
|
"imagePath" : "/home/grobie.home",
|
|
"luksCipher" : "aes",
|
|
"luksCipherMode" : "xts-plain64",
|
|
"luksUuid" : "e63581ba-79fb-4226-b9de-1888393f7573",
|
|
"luksVolumeKeySize" : 32,
|
|
"partitionUuid" : "41f9ce04-c827-4b74-a981-c669f93eb4dc",
|
|
"storage" : "luks",
|
|
"uid" : 60232
|
|
}
|
|
},
|
|
"disposition" : "regular",
|
|
"enforcePasswordPolicy" : false,
|
|
"lastChangeUSec" : 1565950024279735,
|
|
"memberOf" : [
|
|
"wheel"
|
|
],
|
|
"privileged" : {
|
|
"hashedPassword" : [
|
|
"$6$WHBKvAFFT9jKPA4k$OPY4D4TczKN/jOnJzy54DDuOOagCcvxxybrwMbe1SVdm.Bbr.zOmBdATp.QrwZmvqyr8/SafbbQu.QZ2rRvDs/"
|
|
]
|
|
},
|
|
"signature" : [
|
|
{
|
|
"data" : "LU/HeVrPZSzi3MJ0PVHwD5m/xf51XDYCrSpbDRNBdtF4fDVhrN0t2I2OqH/1yXiBidXlV0ptMuQVq8KVICdEDw==",
|
|
"key" : "-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEA/QT6kQWOAMhDJf56jBmszEQQpJHqDsGDMZOdiptBgRk=\n-----END PUBLIC KEY-----\n"
|
|
}
|
|
],
|
|
"userName" : "grobie",
|
|
"status" : {
|
|
"15e19cf24e004b949ddaac60c74aa165" : {
|
|
"goodAuthenticationCounter" : 16,
|
|
"lastGoodAuthenticationUSec" : 1566309343044322,
|
|
"rateLimitBeginUSec" : 1566309342340723,
|
|
"rateLimitCount" : 1,
|
|
"state" : "inactive",
|
|
"service" : "io.systemd.Home",
|
|
"diskSize" : 161118667776,
|
|
"diskCeiling" : 190371729408,
|
|
"diskFloor" : 5242880,
|
|
"signedLocally" : true
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
When `systemd-homed.service` manages a home directory it will also include a
|
|
version of the user record in the home directory itself in the `~/.identity`
|
|
file. This version lacks the `binding` and `status` sections which are used for
|
|
local management of the user, but are not intended to be portable between
|
|
systems. It would hence look like this:
|
|
|
|
```json
|
|
{
|
|
"autoLogin" : true,
|
|
"disposition" : "regular",
|
|
"enforcePasswordPolicy" : false,
|
|
"lastChangeUSec" : 1565950024279735,
|
|
"memberOf" : [
|
|
"wheel"
|
|
],
|
|
"privileged" : {
|
|
"hashedPassword" : [
|
|
"$6$WHBKvAFFT9jKPA4k$OPY4D4TczKN/jOnJzy54DDuOOagCcvxxybrwMbe1SVdm.Bbr.zOmBdATp.QrwZmvqyr8/SafbbQu.QZ2rRvDs/"
|
|
]
|
|
},
|
|
"signature" : [
|
|
{
|
|
"data" : "LU/HeVrPZSzi3MJ0PVHwD5m/xf51XDYCrSpbDRNBdtF4fDVhrN0t2I2OqH/1yXiBidXlV0ptMuQVq8KVICdEDw==",
|
|
"key" : "-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEA/QT6kQWOAMhDJf56jBmszEQQpJHqDsGDMZOdiptBgRk=\n-----END PUBLIC KEY-----\n"
|
|
}
|
|
],
|
|
"userName" : "grobie",
|
|
}
|
|
```
|