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 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

       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).