From 97c26c1924b076ef23ebe4381558e8aa025712b2 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 16:54:37 +0200 Subject: Adding upstream version 1:4.13+dfsg1. Signed-off-by: Daniel Baumann --- man/man5/subuid.5 | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 man/man5/subuid.5 (limited to 'man/man5/subuid.5') diff --git a/man/man5/subuid.5 b/man/man5/subuid.5 new file mode 100644 index 0000000..655fbb9 --- /dev/null +++ b/man/man5/subuid.5 @@ -0,0 +1,120 @@ +'\" t +.\" Title: subuid +.\" Author: Eric Biederman +.\" Generator: DocBook XSL Stylesheets vsnapshot +.\" Date: 11/08/2022 +.\" Manual: File Formats and Configuration Files +.\" Source: shadow-utils 4.13 +.\" Language: English +.\" +.TH "SUBUID" "5" "11/08/2022" "shadow\-utils 4\&.13" "File Formats and Configuration" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +subuid \- the configuration for subordinate user ids +.SH "DESCRIPTION" +.PP +Subuid authorizes a user id to map ranges of user ids from its namespace into child namespaces\&. +.PP +The delegation of the subordinate uids can be configured via the +\fIsubid\fR +field in +/etc/nsswitch\&.conf +file\&. Only one value can be set as the delegation source\&. Setting this field to +\fIfiles\fR +configures the delegation of uids to +/etc/subuid\&. Setting any other value treats the delegation as a plugin following with a name of the form +\fIlibsubid_$value\&.so\fR\&. If the value or plugin is missing, then the subordinate uid delegation falls back to +\fIfiles\fR\&. +.PP +Note, that +\fBuseradd\fR +will only create entries in +/etc/subuid +if subid delegation is managed via subid files\&. +.SH "LOCAL SUBORDINATE DELEGATION" +.PP +Each line in +/etc/subuid +contains a user name and a range of subordinate user ids that user is allowed to use\&. This is specified with three fields delimited by colons (\(lq:\(rq)\&. These fields are: +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +login name or UID +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +numerical subordinate user ID +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +numerical subordinate user ID count +.RE +.PP +This file specifies the user IDs that ordinary users can use, with the +\fBnewuidmap\fR +command, to configure uid mapping in a user namespace\&. +.PP +Multiple ranges may be specified per user\&. +.PP +When large number of entries (10000\-100000 or more) are defined in +/etc/subuid, parsing performance penalty will become noticeable\&. In this case it is recommended to use UIDs instead of login names\&. Benchmarks have shown speed\-ups up to 20x\&. +.SH "FILES" +.PP +/etc/subuid +.RS 4 +Per user subordinate user IDs\&. +.RE +.PP +/etc/subuid\- +.RS 4 +Backup file for /etc/subuid\&. +.RE +.SH "SEE ALSO" +.PP +\fBlogin.defs\fR(5), +\fBnewgidmap\fR(1), +\fBnewuidmap\fR(1), +\fBnewusers\fR(1), +\fBsubgid\fR(5), +\fBuseradd\fR(8), +\fBuserdel\fR(8), +\fBusermod\fR(8), +\fBuser_namespaces\fR(7)\&. -- cgit v1.2.3