newgidmap(1) — Linux manual page

NEWGIDMAP(1)                  User Commands                 NEWGIDMAP(1)

NAME

       newgidmap - set the gid mapping of a user namespace

SYNOPSIS

       newgidmap pid gid lowergid count [gid lowergid count [ ... ]]

DESCRIPTION

       The newgidmap sets /proc/[pid]/gid_map based on its command line
       arguments and the gids allowed. Subgid delegation can either be
       managed via /etc/subgid or through the configured NSS subid
       module. These options are mutually exclusive.

       Note that the root group is not exempted from the requirement for
       a valid /etc/subgid entry.

       After the pid argument, newgidmap expects sets of 3 integers:

       gid
           Beginning of the range of GIDs inside the user namespace.

       lowergid
           Beginning of the range of GIDs outside the user namespace.

       count
           Length of the ranges (both inside and outside the user
           namespace).

       newgidmap verifies that the caller is the owner of the process
       indicated by pid and that for each of the above sets, each of the
       GIDs in the range [lowergid, lowergid+count) is allowed to the
       caller according to /etc/subgid before setting
       /proc/[pid]/gid_map.

       Note that newgidmap may be used only once for a given process.

       Instead of an integer process id, the first argument may be
       specified as fd:N, where the integer N is the file descriptor
       number for the calling process's opened file descriptor for the
       directory /proc/[pid]. In this case, newgidmap will use openat(2)
       to open the gid_map file under that directory, avoiding a TOCTTOU
       in case the process exits and the pid is immediately reused.

OPTIONS

       There currently are no options to the newgidmap command.

FILES

       /etc/subgid
           List of user's subordinate group IDs.

       /proc/[pid]/gid_map
           Mapping of gids from one between user namespaces.

SEE ALSO

       login.defs(5), newusers(8), subgid(5), useradd(8), userdel(8),
       usermod(8).

COLOPHON

       This page is part of the shadow-utils (utilities for managing
       accounts and shadow password files) project.  Information about
       the project can be found at 
       ⟨https://github.com/shadow-maint/shadow⟩.  If you have a bug
       report for this manual page, send it to
       pkg-shadow-devel@alioth-lists.debian.net.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/shadow-maint/shadow⟩ on 2024-06-15.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-13.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

shadow-utils 4.14.0            06/15/2024                   NEWGIDMAP(1)

Pages that refer to this page: getsubids(1), unshare(1), mount_setattr(2), subgid(5), subuid(5), user_namespaces(7)

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