NEWUIDMAP(1)                     User Commands                    NEWUIDMAP(1)

NAME
       newuidmap - set the uid mapping of a user namespace

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

DESCRIPTION
       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 for /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
       There currently are no options to the newuidmap command.

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

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

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

shadow-utils 4.15.1               04/01/2024                      NEWUIDMAP(1)