From f62dd2375e51ddaac4c017c1a97574a5658e7143 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 26 Aug 2019 15:31:17 +0200 Subject: [PATCH] docs: document homed UID range --- docs/UIDS-GIDS.md | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/docs/UIDS-GIDS.md b/docs/UIDS-GIDS.md index ab26bc15f7..255cc71322 100644 --- a/docs/UIDS-GIDS.md +++ b/docs/UIDS-GIDS.md @@ -96,7 +96,15 @@ but downstreams are strongly advised against doing that.) `systemd` defines a number of special UID ranges: -1. 61184…65519 → UIDs for dynamic users are allocated from this range (see the +1. 60001…60513 → UIDs for home directories managed by + [`systemd-homed.service(8)`](https://www.freedesktop.org/software/systemd/man/systemd-homed.service.html). UIDs + from this range are automatically assigned to any home directory discovered, + and persisted locally on first login. On different systems the same user + might get different UIDs assigned in case of conflict, though it is + attempted to make UID assignments stable, by deriving them from a hash of + the user name. + +2. 61184…65519 → UIDs for dynamic users are allocated from this range (see the `DynamicUser=` documentation in [`systemd.exec(5)`](https://www.freedesktop.org/software/systemd/man/systemd.exec.html)). This range has been chosen so that it is below the 16bit boundary (i.e. below @@ -111,7 +119,7 @@ but downstreams are strongly advised against doing that.) user record resolving works correctly without those users being in `/etc/passwd`. -2. 524288…1879048191 → UID range for `systemd-nspawn`'s automatic allocation of +3. 524288…1879048191 → UID range for `systemd-nspawn`'s automatic allocation of per-container UID ranges. When the `--private-users=pick` switch is used (or `-U`) then it will automatically find a so far unused 16bit subrange of this range and assign it to the container. The range is picked so that the upper @@ -232,7 +240,8 @@ the artifacts the container manager persistently leaves in the system. | 5 | `tty` group | `systemd` | `/etc/passwd` | | 6…999 | System users | Distributions | `/etc/passwd` | | 1000…60000 | Regular users | Distributions | `/etc/passwd` + LDAP/NIS/… | -| 60001…61183 | Unused | | | +| 60001…60513 | Human Users (homed) | `systemd` | `nss-systemd` +| 60514…61183 | Unused | | | | 61184…65519 | Dynamic service users | `systemd` | `nss-systemd` | | 65520…65533 | Unused | | | | 65534 | `nobody` user | Linux | `/etc/passwd` + `nss-systemd` |