libpod: Add pasta networking mode

Conceptually equivalent to networking by means of slirp4netns(1),
with a few practical differences:

- pasta(1) forks to background once networking is configured in the
  namespace and quits on its own once the namespace is deleted:
  file descriptor synchronisation and PID tracking are not needed

- port forwarding is configured via command line options at start-up,
  instead of an API socket: this is taken care of right away as we're
  about to start pasta

- there's no need for further selection of port forwarding modes:
  pasta behaves similarly to containers-rootlessport for local binds
  (splice() instead of read()/write() pairs, without L2-L4
  translation), and keeps the original source address for non-local
  connections like slirp4netns does

- IPv6 is not an experimental feature, and enabled by default. IPv6
  port forwarding is supported

- by default, addresses and routes are copied from the host, that is,
  container users will see the same IP address and routes as if they
  were in the init namespace context. The interface name is also
  sourced from the host upstream interface with the first default
  route in the routing table. This is also configurable as documented

- sandboxing and seccomp(2) policies cannot be disabled

- only rootless mode is supported.

See https://passt.top for more details about pasta.

Also add a link to the maintained build of pasta(1) manual as valid
in the man page cross-reference checks: that's where the man page
for the latest build actually is -- it's not on Github and it doesn't
match any existing pattern, so add it explicitly.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Author: sbrivio-rh

cmd/podman/common/netflags.go

@@ -95,7 +95,7 @@ func DefineNetFlags(cmd *cobra.Command) {
 }
 
 // NetFlagsToNetOptions parses the network flags for the given cmd.
-func NetFlagsToNetOptions(opts *entities.NetOptions, flags pflag.FlagSet) (*entities.NetOptions, error) {
+func NetFlagsToNetOptions(opts *entities.NetOptions, flags pflag.FlagSet, pastaNetworkNameExists bool) (*entities.NetOptions, error) {
 	var (
 		err error
 	)
@@ -192,7 +192,7 @@ func NetFlagsToNetOptions(opts *entities.NetOptions, flags pflag.FlagSet) (*enti
 			return nil, err
 		}
 
-		ns, networks, options, err := specgen.ParseNetworkFlag(network)
+		ns, networks, options, err := specgen.ParseNetworkFlag(network, pastaNetworkNameExists)
 		if err != nil {
 			return nil, err
 		}

cmd/podman/containers/create.go

@@ -105,8 +105,15 @@ func init() {
 
 func commonFlags(cmd *cobra.Command) error {
 	var err error
+
+	report, err := registry.ContainerEngine().NetworkExists(registry.Context(), "pasta")
+	if err != nil {
+		return err
+	}
+	pastaNetworkNameExists := report.Value
+
 	flags := cmd.Flags()
-	cliVals.Net, err = common.NetFlagsToNetOptions(nil, *flags)
+	cliVals.Net, err = common.NetFlagsToNetOptions(nil, *flags, pastaNetworkNameExists)
 	if err != nil {
 		return err
 	}

cmd/podman/pods/create.go

@@ -130,12 +130,18 @@ func create(cmd *cobra.Command, args []string) error {
 		createOptions.Infra = false
 	}
 
+	report, err := registry.ContainerEngine().NetworkExists(registry.Context(), "pasta")
+	if err != nil {
+		return err
+	}
+	pastaNetworkNameExists := report.Value
+
 	if !createOptions.Infra {
 		if cmd.Flag("no-hosts").Changed {
 			return fmt.Errorf("cannot specify --no-hosts without an infra container")
 		}
 		flags := cmd.Flags()
-		createOptions.Net, err = common.NetFlagsToNetOptions(nil, *flags)
+		createOptions.Net, err = common.NetFlagsToNetOptions(nil, *flags, pastaNetworkNameExists)
 		if err != nil {
 			return err
 		}
@@ -152,7 +158,7 @@ func create(cmd *cobra.Command, args []string) error {
 	} else {
 		// reassign certain options for lbpod api, these need to be populated in spec
 		flags := cmd.Flags()
-		infraOptions.Net, err = common.NetFlagsToNetOptions(nil, *flags)
+		infraOptions.Net, err = common.NetFlagsToNetOptions(nil, *flags, pastaNetworkNameExists)
 		if err != nil {
 			return err
 		}

docs/source/markdown/options/network.md

@@ -35,3 +35,42 @@ Valid _mode_ values are:
   - **port_handler=rootlesskit**: Use rootlesskit for port forwarding. Default.
   Note: Rootlesskit changes the source IP address of incoming packets to an IP address in the container network namespace, usually `10.0.2.100`. If your application requires the real source IP address, e.g. web server logs, use the slirp4netns port handler. The rootlesskit port handler is also used for rootless containers when connected to user-defined networks.
   - **port_handler=slirp4netns**: Use the slirp4netns port forwarding, it is slower than rootlesskit but preserves the correct source IP address. This port handler cannot be used for user-defined networks.
+
+- **pasta[:OPTIONS,...]**: use **pasta**(1) to create a user-mode networking
+    stack. \
+    This is only supported in rootless mode. \
+    By default, IPv4 and IPv6 addresses and routes, as well as the pod interface
+    name, are copied from the host. If port forwarding isn't configured, ports
+    will be forwarded dynamically as services are bound on either side (init
+    namespace or container namespace). Port forwarding preserves the original
+    source IP address. Options described in pasta(1) can be specified as
+    comma-separated arguments. \
+    In terms of pasta(1) options, **--config-net** is given by default, in
+    order to configure networking when the container is started, and
+    **--no-map-gw** is also assumed by default, to avoid direct access from
+    container to host using the gateway address. The latter can be overridden
+    by passing **--map-gw** in the pasta-specific options (despite not being an
+    actual pasta(1) option). \
+    Also, **-t none** and **-u none** are passed if, respectively, no TCP or
+    UDP port forwarding from host to container is configured, to disable
+    automatic port forwarding based on bound ports. Similarly, **-T none** and
+    **-U none** are given to disable the same functionality from container to
+    host. \
+    Some examples:
+    - **pasta:--map-gw**: Allow the container to directly reach the host using the
+        gateway address.
+    - **pasta:--mtu,1500**: Specify a 1500 bytes MTU for the _tap_ interface in
+        the container.
+    - **pasta:--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,-m,1500,--no-ndp,--no-dhcpv6,--no-dhcp**,
+        equivalent to default slirp4netns(1) options: disable IPv6, assign
+        `10.0.2.0/24` to the `tap0` interface in the container, with gateway
+        `10.0.2.3`, enable DNS forwarder reachable at `10.0.2.3`, set MTU to 1500
+        bytes, disable NDP, DHCPv6 and DHCP support.
+    - **pasta:-I,tap0,--ipv4-only,-a,10.0.2.0,-n,24,-g,10.0.2.2,--dns-forward,10.0.2.3,--no-ndp,--no-dhcpv6,--no-dhcp**,
+        equivalent to default slirp4netns(1) options with Podman overrides: same as
+        above, but leave the MTU to 65520 bytes
+    - **pasta:-t,auto,-u,auto,-T,auto,-U,auto**: enable automatic port forwarding
+        based on observed bound ports from both host and container sides
+    - **pasta:-T,5201**: enable forwarding of TCP port 5201 from container to
+        host, using the loopback interface instead of the tap interface for improved
+        performance

docs/source/markdown/podman-create.1.md.in

@@ -491,8 +491,11 @@ In order for users to run rootless, there must be an entry for their username in
 
 Rootless Podman works better if the fuse-overlayfs and slirp4netns packages are installed.
 The fuse-overlayfs package provides a userspace overlay storage driver, otherwise users need to use
-the vfs storage driver, which is diskspace expensive and does not perform well. slirp4netns is
-required for VPN, without it containers need to be run with the --network=host flag.
+the vfs storage driver, which can be disk space expensive and less performant
+than other drivers.
+
+To enable VPN on the container, slirp4netns or pasta needs to be specified;
+without either, containers need to be run with the --network=host flag.
 
 ## ENVIRONMENT
 
@@ -541,7 +544,7 @@ page.
 NOTE: Use the environment variable `TMPDIR` to change the temporary storage location of downloaded container images. Podman defaults to use `/var/tmp`.
 
 ## SEE ALSO
-**[podman(1)](podman.1.md)**, **[podman-save(1)](podman-save.1.md)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-attach(1)](podman-attach.1.md)**, **[podman-pod-create(1)](podman-pod-create.1.md)**, **[podman-port(1)](podman-port.1.md)**, **[podman-start(1)](podman-start.1.md)**, **[podman-kill(1)](podman-kill.1.md)**, **[podman-stop(1)](podman-stop.1.md)**, **[podman-generate-systemd(1)](podman-generate-systemd.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[systemd.unit(5)](https://www.freedesktop.org/software/systemd/man/systemd.unit.html)**, **[setsebool(8)](https://man7.org/linux/man-pages/man8/setsebool.8.html)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[fuse-overlayfs(1)](https://github.com/containers/fuse-overlayfs/blob/main/fuse-overlayfs.1.md)**, **proc(5)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**, **personality(2)**
+**[podman(1)](podman.1.md)**, **[podman-save(1)](podman-save.1.md)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-attach(1)](podman-attach.1.md)**, **[podman-pod-create(1)](podman-pod-create.1.md)**, **[podman-port(1)](podman-port.1.md)**, **[podman-start(1)](podman-start.1.md)**, **[podman-kill(1)](podman-kill.1.md)**, **[podman-stop(1)](podman-stop.1.md)**, **[podman-generate-systemd(1)](podman-generate-systemd.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[systemd.unit(5)](https://www.freedesktop.org/software/systemd/man/systemd.unit.html)**, **[setsebool(8)](https://man7.org/linux/man-pages/man8/setsebool.8.html)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[pasta(1)](https://passt.top/builds/latest/web/passt.1.html)**, **[fuse-overlayfs(1)](https://github.com/containers/fuse-overlayfs/blob/main/fuse-overlayfs.1.md)**, **proc(5)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**, **personality(2)**
 
 ## HISTORY
 October 2017, converted from Docker documentation to Podman by Dan Walsh for Podman `<dwalsh@redhat.com>`

docs/source/markdown/podman-pod-create.1.md.in

@@ -219,6 +219,8 @@ $ podman pod create --network slirp4netns:outbound_addr=127.0.0.1,allow_host_loo
 
 $ podman pod create --network slirp4netns:cidr=192.168.0.0/24
 
+$ podman pod create --network pasta
+
 $ podman pod create --network net1:ip=10.89.1.5 --network net2:ip=10.89.10.10
 ```
 

docs/source/markdown/podman-run.1.md.in

@@ -837,8 +837,11 @@ In order for users to run rootless, there must be an entry for their username in
 
 Rootless Podman works better if the fuse-overlayfs and slirp4netns packages are installed.
 The **fuse-overlayfs** package provides a userspace overlay storage driver, otherwise users need to use
-the **vfs** storage driver, which is diskspace expensive and does not perform well. slirp4netns is
-required for VPN, without it containers need to be run with the **--network=host** flag.
+the **vfs** storage driver, which can be disk space expensive and less
+performant than other drivers.
+
+To enable VPN on the container, slirp4netns or pasta needs to be specified;
+without either, containers need to be run with the --network=host flag.
 
 ## ENVIRONMENT
 
@@ -885,7 +888,7 @@ page.
 NOTE: Use the environment variable `TMPDIR` to change the temporary storage location of downloaded container images. Podman defaults to use `/var/tmp`.
 
 ## SEE ALSO
-**[podman(1)](podman.1.md)**, **[podman-save(1)](podman-save.1.md)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-attach(1)](podman-attach.1.md)**, **[podman-pod-create(1)](podman-pod-create.1.md)**, **[podman-port(1)](podman-port.1.md)**, **[podman-start(1)](podman-start.1.md)**, **[podman-kill(1)](podman-kill.1.md)**, **[podman-stop(1)](podman-stop.1.md)**, **[podman-generate-systemd(1)](podman-generate-systemd.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[systemd.unit(5)](https://www.freedesktop.org/software/systemd/man/systemd.unit.html)**, **[setsebool(8)](https://man7.org/linux/man-pages/man8/setsebool.8.html)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[fuse-overlayfs(1)](https://github.com/containers/fuse-overlayfs/blob/main/fuse-overlayfs.1.md)**, **proc(5)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**, **personality(2)**
+**[podman(1)](podman.1.md)**, **[podman-save(1)](podman-save.1.md)**, **[podman-ps(1)](podman-ps.1.md)**, **[podman-attach(1)](podman-attach.1.md)**, **[podman-pod-create(1)](podman-pod-create.1.md)**, **[podman-port(1)](podman-port.1.md)**, **[podman-start(1)](podman-start.1.md)**, **[podman-kill(1)](podman-kill.1.md)**, **[podman-stop(1)](podman-stop.1.md)**, **[podman-generate-systemd(1)](podman-generate-systemd.1.md)**, **[podman-rm(1)](podman-rm.1.md)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[systemd.unit(5)](https://www.freedesktop.org/software/systemd/man/systemd.unit.html)**, **[setsebool(8)](https://man7.org/linux/man-pages/man8/setsebool.8.html)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[pasta(1)](https://passt.top/builds/latest/web/passt.1.html)**, **[fuse-overlayfs(1)](https://github.com/containers/fuse-overlayfs/blob/main/fuse-overlayfs.1.md)**, **proc(5)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**, **personality(2)**
 
 ## HISTORY
 September 2018, updated by Kunal Kushwaha `<kushwaha_kunal_v7@lab.ntt.co.jp>`

docs/source/markdown/podman.1.md

@@ -88,7 +88,7 @@ Set libpod namespace. Namespaces are used to separate groups of containers and p
 When namespace is set, created containers and pods will join the given namespace, and only containers and pods in the given namespace will be visible to Podman.
 
 #### **--network-cmd-path**=*path*
-Path to the command binary to use for setting up a network.  It is currently only used for setting up a slirp4netns network.  If "" is used then the binary is looked up using the $PATH environment variable.
+Path to the command binary to use for setting up a network.  It is currently only used for setting up a slirp4netns(1) or pasta(1) network.  If "" is used then the binary is looked up using the $PATH environment variable.
 
 #### **--network-config-dir**=*directory*
 
@@ -422,7 +422,9 @@ See the `subuid(5)` and `subgid(5)` man pages for more information.
 
 Images are pulled under `XDG_DATA_HOME` when specified, otherwise in the home directory of the user under `.local/share/containers/storage`.
 
-Currently the slirp4netns package is required to be installed to create a network device, otherwise rootless containers need to run in the network namespace of the host.
+Currently slirp4netns or pasta is required to be installed to create a network
+device, otherwise rootless containers need to run in the network namespace of
+the host.
 
 In certain environments like HPC (High Performance Computing), users cannot take advantage of the additional UIDs and GIDs from the /etc/subuid and /etc/subgid systems.  However, in this environment, rootless Podman can operate with a single UID.  To make this work, set the `ignore_chown_errors` option in the /etc/containers/storage.conf or in ~/.config/containers/storage.conf files. This option tells Podman when pulling an image to ignore chown errors when attempting to change a file in a container image to match the non-root UID in the image. This means all files get saved as the user's UID. Note this could cause issues when running the container.
 
@@ -435,7 +437,7 @@ The Network File System (NFS) and other distributed file systems (for example: L
 For more information, please refer to the [Podman Troubleshooting Page](https://github.com/containers/podman/blob/main/troubleshooting.md).
 
 ## SEE ALSO
-**[containers-mounts.conf(5)](https://github.com/containers/common/blob/main/docs/containers-mounts.conf.5.md)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[containers-registries.conf(5)](https://github.com/containers/image/blob/main/docs/containers-registries.conf.5.md)**, **[containers-storage.conf(5)](https://github.com/containers/storage/blob/main/docs/containers-storage.conf.5.md)**, **[buildah(1)](https://github.com/containers/buildah/blob/main/docs/buildah.1.md)**, **oci-hooks(5)**, **[containers-policy.json(5)](https://github.com/containers/image/blob/main/docs/containers-policy.json.5.md)**, **[crun(1)](https://github.com/containers/crun/blob/main/crun.1.md)**, **[runc(8)](https://github.com/opencontainers/runc/blob/master/man/runc.8.md)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**
+**[containers-mounts.conf(5)](https://github.com/containers/common/blob/main/docs/containers-mounts.conf.5.md)**, **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)**, **[containers-registries.conf(5)](https://github.com/containers/image/blob/main/docs/containers-registries.conf.5.md)**, **[containers-storage.conf(5)](https://github.com/containers/storage/blob/main/docs/containers-storage.conf.5.md)**, **[buildah(1)](https://github.com/containers/buildah/blob/main/docs/buildah.1.md)**, **oci-hooks(5)**, **[containers-policy.json(5)](https://github.com/containers/image/blob/main/docs/containers-policy.json.5.md)**, **[crun(1)](https://github.com/containers/crun/blob/main/crun.1.md)**, **[runc(8)](https://github.com/opencontainers/runc/blob/master/man/runc.8.md)**, **[subuid(5)](https://www.unix.com/man-page/linux/5/subuid)**, **[subgid(5)](https://www.unix.com/man-page/linux/5/subgid)**, **[slirp4netns(1)](https://github.com/rootless-containers/slirp4netns/blob/master/slirp4netns.1.md)**, **[pasta(1)](https://passt.top/builds/latest/web/passt.1.html)**, **[conmon(8)](https://github.com/containers/conmon/blob/main/docs/conmon.8.md)**
 
 ## HISTORY
 Dec 2016, Originally compiled by Dan Walsh <dwalsh@redhat.com>

hack/xref-helpmsgs-manpages

@@ -619,6 +619,8 @@ sub _is_valid_external_link {
         return 1 if $link eq "https://www.freedesktop.org/software/systemd/man/$base.html";
     }
 
+    return 1 if $link eq "https://passt.top/builds/latest/web/passt.1.html";
+
     return;
 }
 

libpod/networking_common.go

@@ -133,7 +133,8 @@ func (r *Runtime) teardownCNI(ctr *Container) error {
 		return err
 	}
 
-	if !ctr.config.NetMode.IsSlirp4netns() && len(networks) > 0 {
+	if !ctr.config.NetMode.IsSlirp4netns() &&
+		!ctr.config.NetMode.IsPasta() && len(networks) > 0 {
 		netOpts := ctr.getNetworkOptions(networks)
 		return r.teardownNetwork(ctr.state.NetNS.Path(), netOpts)
 	}