podman-unshare(1)

NAME

podman-unshare - Run a command inside of a modified user namespace

SYNOPSIS

podman unshare [--] [command]

DESCRIPTION

Launches a process (by default, $SHELL) in a new user namespace. The user namespace is configured so that the invoking user's UID and primary GID appear to be UID 0 and GID 0, respectively. Any ranges which match that user and group in /etc/subuid and /etc/subgid are also mapped in as themselves with the help of the newuidmap(1) and newgidmap(1) helpers.

podman unshare is useful for troubleshooting unprivileged operations and for manually clearing storage and other data related to images and containers.

It is also useful if you want to use the podman mount command. If an unprivileged user wants to mount and work with a container, then they need to execute podman unshare. Executing podman mount fails for unprivileged users unless the user is running inside a podman unshare session.

The unshare session defines two environment variables:

    •   CONTAINERS_GRAPHROOT: the path to the persistent container's data.

    •   CONTAINERS_RUNROOT: the path to the volatile container's data.

OPTIONS

  --help, -h

Print usage statement

  --rootless-cni

Join the rootless network namespace used for CNI networking. It can be used to connect to a rootless container via IP address (CNI networking). This is otherwise not possible from the host network namespace. Note: Using this option with more than one unshare session can have unexpected results.

Exit Codes

The exit code from podman unshare gives information about why the container failed to run or why it exited. When podman unshare commands exit with a non-zero code, the exit codes follow the chroot standard, see below:

125 The error is with podman itself

    $ podman unshare --foo; echo $?
    Error: unknown flag: --foo
    125

126 Executing a contained command and the command cannot be invoked

    $ podman unshare /etc; echo $?
    Error: fork/exec /etc: permission denied
    126

127 Executing a contained command and the command cannot be found

    $ podman run busybox foo; echo $?
    Error: fork/exec /usr/bin/bogus: no such file or directory
    127

Exit code contained command exit code

    $ podman run busybox /bin/sh -c 'exit 3'; echo $?
    3

EXAMPLE

    $ podman unshare id
    uid=0(root) gid=0(root) groups=0(root),65534(nobody)
    $ podman unshare cat /proc/self/uid_map /proc/self/gid_map
             0       1000          1
             1      10000      65536
             0       1000          1
             1      10000      65536
    $ podman unshare --rootless-cni ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host
           valid_lft forever preferred_lft forever
    2: tap0: <BROADCAST,UP,LOWER_UP> mtu 65520 qdisc fq_codel state UNKNOWN group default qlen 1000
        link/ether 36:0e:4a:c7:45:7e brd ff:ff:ff:ff:ff:ff
        inet 10.0.2.100/24 brd 10.0.2.255 scope global tap0
           valid_lft forever preferred_lft forever
        inet6 fe80::340e:4aff:fec7:457e/64 scope link
           valid_lft forever preferred_lft forever
    3: cni-podman2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether 5e:3a:71:d2:b4:3a brd ff:ff:ff:ff:ff:ff
        inet 10.89.1.1/24 brd 10.89.1.255 scope global cni-podman2
           valid_lft forever preferred_lft forever
        inet6 fe80::5c3a:71ff:fed2:b43a/64 scope link
           valid_lft forever preferred_lft forever
    4: vethd4ba3a2f@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master cni-podman2 state UP group default
        link/ether 8a:c9:56:32:17:0c brd ff:ff:ff:ff:ff:ff link-netnsid 0
        inet6 fe80::88c9:56ff:fe32:170c/64 scope link
           valid_lft forever preferred_lft forever

SEE ALSO

podman(1), podman-mount(1), namespaces(7), newuidmap(1), newgidmap(1), user_namespaces(7)