newgidmap(1) — Linux manual page

NEWGIDMAP(1)                  User Commands                 NEWGIDMAP(1)

NAME         top

       newgidmap - set the gid mapping of a user namespace

SYNOPSIS         top

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

DESCRIPTION         top

       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         top

       There currently are no options to the newgidmap command.

FILES         top

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

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

SEE ALSO         top

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

COLOPHON         top

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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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