newuidmap(1) — Linux manual page

NEWUIDMAP(1)                  User Commands                 NEWUIDMAP(1)

NAME         top

       newuidmap - set the uid mapping of a user namespace

SYNOPSIS         top

       newuidmap pid uid loweruid count [uid loweruid count [ ... ]]

DESCRIPTION         top

       The newuidmap sets /proc/[pid]/uid_map based on its command line
       arguments and the uids allowed. Subuid delegation can either be
       managed via /etc/subuid or through the configured NSS subid
       module. These options are mutually exclusive.

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

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

       uid
           Beginning of the range of UIDs inside the user namespace.

       loweruid
           Beginning of the range of UIDs outside the user namespace.

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

       newuidmap verifies that the caller is the owner of the process
       indicated by pid and that for each of the above sets, each of the
       UIDs in the range [loweruid, loweruid+count) is allowed to the
       caller according to /etc/subuid before setting
       /proc/[pid]/uid_map.

       Note that newuidmap 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, newuidmap will use openat(2)
       to open the uid_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 newuidmap command.

FILES         top

       /etc/subuid
           List of user's subordinate user IDs.

       /proc/[pid]/uid_map
           Mapping of uids from one between user namespaces.

SEE ALSO         top

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

COLOPHON         top

       This page is part of the shadow-utils (utilities for managing
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shadow-utils 4.14.0            06/15/2024                   NEWUIDMAP(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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