Merge pull request #13881 from rhatdan/userns

Add support for --userns=nomap

cmd/podman/common/completion.go

@@ -756,7 +756,7 @@ func AutocompleteNamespace(cmd *cobra.Command, args []string, toComplete string)
 // -> same as AutocompleteNamespace with "auto", "keep-id" added
 func AutocompleteUserNamespace(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 	results, directive := AutocompleteNamespace(cmd, args, toComplete)
-	results = append(results, "auto", "keep-id")
+	results = append(results, "auto", "keep-id", "nomap")
 	return results, directive
 }
 

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

@@ -1225,6 +1225,15 @@ Without this argument the command will be run as root in the container.
 
 Set the user namespace mode for the container. It defaults to the **PODMAN_USERNS** environment variable. An empty value ("") means user namespaces are disabled unless an explicit mapping is set with the **--uidmap** and **--gidmap** options.
 
+Rootless user --userns=Key mappings:
+
+Key       | Host User |  Container User
+----------|---------------|---------------------
+""        |$UID           |0 (Default User account mapped to root user in container.)
+keep-id   |$UID           |$UID (Map user account to same UID within container.)
+auto      |$UID           | nil (Host User UID is not mapped into container.)
+nomap     |$UID           | nil (Host User UID is not mapped into container.)
+
 Valid _mode_ values are:
 
 **auto**[:_OPTIONS,..._]: automatically create a unique user namespace.
@@ -1247,6 +1256,8 @@ Podman allocates unique ranges of UIDs and GIDs from the `containers` subordinat
 
 **keep-id**: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is ignored for containers created by the root user.
 
+**nomap**: creates a user namespace where the current rootless user's UID:GID are not mapped into the container. This option is ignored for containers created by the root user.
+
 **ns:**_namespace_: run the container in the given existing user namespace.
 
 **private**: create a new namespace for the container.

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

@@ -308,14 +308,30 @@ several times to map different ranges.
 
 Set the user namespace mode for all the containers in a pod. It defaults to the **PODMAN_USERNS** environment variable. An empty value ("") means user namespaces are disabled.
 
+Rootless user --userns=Key mappings:
+
+Key       | Host User |  Container User
+----------|---------------|---------------------
+""        |$UID           |0 (Default User account mapped to root user in container.)
+keep-id   |$UID           |$UID (Map user account to same UID within container.)
+auto      |$UID           | nil (Host User UID is not mapped into container.)
+nomap     |$UID           | nil (Host User UID is not mapped into container.)
+
 Valid _mode_ values are:
 
-- *auto[:*_OPTIONS,..._*]*: automatically create a namespace. It is possible to specify these options to `auto`:
+  - *auto[:*_OPTIONS,..._*]*: automatically create a namespace. It is possible to specify these options to `auto`:
+
   - *gidmapping=*_CONTAINER_GID:HOST_GID:SIZE_ to force a GID mapping to be present in the user namespace.
+
   - *size=*_SIZE_: to specify an explicit size for the automatic user namespace. e.g. `--userns=auto:size=8192`. If `size` is not specified, `auto` will estimate a size for the user namespace.
+
   - *uidmapping=*_CONTAINER_UID:HOST_UID:SIZE_ to force a UID mapping to be present in the user namespace.
-- *host*: run in the user namespace of the caller. The processes running in the container will have the same privileges on the host as any other process launched by the calling user (default).
-- *keep-id*: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is ignored for containers created by the root user.
+
+  - *host*: run in the user namespace of the caller. The processes running in the container will have the same privileges on the host as any other process launched by the calling user (default).
+
+  - *keep-id*: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is ignored for containers created by the root user.
+
+  - *nomap*: creates a user namespace where the current rootless user's UID:GID are not mapped into the container. This option is ignored for containers created by the root user.
 
 #### **--volume**, **-v**[=*[[SOURCE-VOLUME|HOST-DIR:]CONTAINER-DIR[:OPTIONS]]*]
 

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

@@ -1290,6 +1290,15 @@ When a user namespace is not in use, the UID and GID used within the container a
 
 Set the user namespace mode for the container. It defaults to the **PODMAN_USERNS** environment variable. An empty value ("") means user namespaces are disabled unless an explicit mapping is set with the **--uidmap** and **--gidmap** options.
 
+Rootless user --userns=Key mappings:
+
+Key       | Host User |  Container User
+----------|---------------|---------------------
+""        |$UID           |0 (Default User account mapped to root user in container.)
+keep-id   |$UID           |$UID (Map user account to same UID within container.)
+auto      |$UID           | nil (Host User UID is not mapped into container.)
+nomap     |$UID           | nil (Host User UID is not mapped into container.)
+
 Valid _mode_ values are:
 
 **auto**[:_OPTIONS,..._]: automatically create a unique user namespace.
@@ -1299,6 +1308,7 @@ The `--userns=auto` flag, requires that the user name `containers` and a range o
 Example: `containers:2147483647:2147483648`.
 
 Podman allocates unique ranges of UIDs and GIDs from the `containers` subordinate user ids. The size of the ranges is based on the number of UIDs required in the image. The number of UIDs and GIDs can be overridden with the `size` option.
+
 The rootless option `--userns=keep-id` uses all the subuids and subgids of the user. Using `--userns=auto` when starting new containers will not work as long as any containers exist that were started with `--userns=keep-id`.
 
   Valid `auto` options:
@@ -1313,10 +1323,11 @@ The rootless option `--userns=keep-id` uses all the subuids and subgids of the u
 
 **keep-id**: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is ignored for containers created by the root user.
 
+**nomap**: creates a user namespace where the current rootless user's UID:GID are not mapped into the container. This option is ignored for containers created by the root user.
+
 **ns:**_namespace_: run the container in the given existing user namespace.
 
 **private**: create a new namespace for the container.
-
 This option is incompatible with **--gidmap**, **--uidmap**, **--subuidname** and **--subgidname**.
 
 #### **--uts**=*mode*

pkg/domain/infra/runtime_libpod.go

@@ -276,46 +276,47 @@ func ParseIDMapping(mode namespaces.UsernsMode, uidMapSlice, gidMapSlice []strin
 		if len(subUIDMap) > 0 || len(subGIDMap) > 0 {
 			return nil, errors.New("cannot specify subuidmap or subgidmap with --userns=keep-id")
 		}
-		if rootless.IsRootless() {
-			min := func(a, b int) int {
-				if a < b {
-					return a
-				}
-				return b
+		if !rootless.IsRootless() {
+			return nil, errors.New("keep-id is only supported in rootless mode")
+		}
+		min := func(a, b int) int {
+			if a < b {
+				return a
 			}
+			return b
+		}
 
-			uid := rootless.GetRootlessUID()
-			gid := rootless.GetRootlessGID()
-
-			uids, gids, err := rootless.GetConfiguredMappings()
-			if err != nil {
-				return nil, errors.Wrapf(err, "cannot read mappings")
-			}
-			maxUID, maxGID := 0, 0
-			for _, u := range uids {
-				maxUID += u.Size
-			}
-			for _, g := range gids {
-				maxGID += g.Size
-			}
+		uid := rootless.GetRootlessUID()
+		gid := rootless.GetRootlessGID()
 
-			options.UIDMap, options.GIDMap = nil, nil
+		uids, gids, err := rootless.GetConfiguredMappings()
+		if err != nil {
+			return nil, errors.Wrapf(err, "cannot read mappings")
+		}
+		maxUID, maxGID := 0, 0
+		for _, u := range uids {
+			maxUID += u.Size
+		}
+		for _, g := range gids {
+			maxGID += g.Size
+		}
 
-			options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(uid, maxUID)})
-			options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid, HostID: 0, Size: 1})
-			if maxUID > uid {
-				options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid + 1, HostID: uid + 1, Size: maxUID - uid})
-			}
+		options.UIDMap, options.GIDMap = nil, nil
 
-			options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(gid, maxGID)})
-			options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid, HostID: 0, Size: 1})
-			if maxGID > gid {
-				options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid + 1, HostID: gid + 1, Size: maxGID - gid})
-			}
+		options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(uid, maxUID)})
+		options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid, HostID: 0, Size: 1})
+		if maxUID > uid {
+			options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid + 1, HostID: uid + 1, Size: maxUID - uid})
+		}
 
-			options.HostUIDMapping = false
-			options.HostGIDMapping = false
+		options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: min(gid, maxGID)})
+		options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid, HostID: 0, Size: 1})
+		if maxGID > gid {
+			options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid + 1, HostID: gid + 1, Size: maxGID - gid})
 		}
+
+		options.HostUIDMapping = false
+		options.HostGIDMapping = false
 		// Simply ignore the setting and do not setup an inner namespace for root as it is a no-op
 		return &options, nil
 	}

pkg/namespaces/namespaces.go

@@ -96,6 +96,11 @@ func (n UsernsMode) IsKeepID() bool {
 	return n == "keep-id"
 }
 
+// IsNoMap indicates whether container uses a mapping where the (uid, gid) on the host is not present in the namespace.
+func (n UsernsMode) IsNoMap() bool {
+	return n == "nomap"
+}
+
 // IsAuto indicates whether container uses the "auto" userns mode.
 func (n UsernsMode) IsAuto() bool {
 	parts := strings.Split(string(n), ":")
@@ -158,7 +163,7 @@ func (n UsernsMode) IsPrivate() bool {
 func (n UsernsMode) Valid() bool {
 	parts := strings.Split(string(n), ":")
 	switch mode := parts[0]; mode {
-	case "", privateType, hostType, "keep-id", nsType, "auto":
+	case "", privateType, hostType, "keep-id", nsType, "auto", "nomap":
 	case containerType:
 		if len(parts) != 2 || parts[1] == "" {
 			return false

pkg/specgen/generate/namespaces.go

@@ -165,21 +165,19 @@ func namespaceOptions(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.
 	// User
 	switch s.UserNS.NSMode {
 	case specgen.KeepID:
-		if rootless.IsRootless() {
-			toReturn = append(toReturn, libpod.WithAddCurrentUserPasswdEntry())
-
-			// If user is not overridden, set user in the container
-			// to user running Podman.
-			if s.User == "" {
-				_, uid, gid, err := util.GetKeepIDMapping()
-				if err != nil {
-					return nil, err
-				}
-				toReturn = append(toReturn, libpod.WithUser(fmt.Sprintf("%d:%d", uid, gid)))
+		if !rootless.IsRootless() {
+			return nil, errors.New("keep-id is only supported in rootless mode")
+		}
+		toReturn = append(toReturn, libpod.WithAddCurrentUserPasswdEntry())
+
+		// If user is not overridden, set user in the container
+		// to user running Podman.
+		if s.User == "" {
+			_, uid, gid, err := util.GetKeepIDMapping()
+			if err != nil {
+				return nil, err
 			}
-		} else {
-			// keep-id as root doesn't need a user namespace
-			s.UserNS.NSMode = specgen.Host
+			toReturn = append(toReturn, libpod.WithUser(fmt.Sprintf("%d:%d", uid, gid)))
 		}
 	case specgen.FromPod:
 		if pod == nil || infraCtr == nil {

pkg/specgen/namespaces.go

@@ -55,6 +55,10 @@ const (
 	// of the namespace itself.
 	// Only used with the user namespace, invalid otherwise.
 	KeepID NamespaceMode = "keep-id"
+	// NoMap indicates a user namespace to keep the owner uid out
+	// of the namespace itself.
+	// Only used with the user namespace, invalid otherwise.
+	NoMap NamespaceMode = "no-map"
 	// Auto indicates to automatically create a user namespace.
 	// Only used with the user namespace, invalid otherwise.
 	Auto NamespaceMode = "auto"
@@ -121,6 +125,11 @@ func (n *Namespace) IsKeepID() bool {
 	return n.NSMode == KeepID
 }
 
+// IsNoMap indicates the namespace is NoMap
+func (n *Namespace) IsNoMap() bool {
+	return n.NSMode == NoMap
+}
+
 func (n *Namespace) String() string {
 	if n.Value != "" {
 		return fmt.Sprintf("%s:%s", n.NSMode, n.Value)
@@ -133,7 +142,7 @@ func validateUserNS(n *Namespace) error {
 		return nil
 	}
 	switch n.NSMode {
-	case Auto, KeepID:
+	case Auto, KeepID, NoMap:
 		return nil
 	}
 	return n.validate()
@@ -299,6 +308,9 @@ func ParseUserNamespace(ns string) (Namespace, error) {
 	case ns == "keep-id":
 		toReturn.NSMode = KeepID
 		return toReturn, nil
+	case ns == "nomap":
+		toReturn.NSMode = NoMap
+		return toReturn, nil
 	case ns == "":
 		toReturn.NSMode = Host
 		return toReturn, nil
@@ -548,20 +560,41 @@ func SetupUserNS(idmappings *storage.IDMappingOptions, userns Namespace, g *gene
 		g.SetProcessUID(uint32(uid))
 		g.SetProcessGID(uint32(gid))
 		user = fmt.Sprintf("%d:%d", uid, gid)
-		fallthrough
-	case Private:
-		if err := g.AddOrReplaceLinuxNamespace(string(spec.UserNamespace), ""); err != nil {
+		if err := privateUserNamespace(idmappings, g); err != nil {
 			return user, err
 		}
-		if idmappings == nil || (len(idmappings.UIDMap) == 0 && len(idmappings.GIDMap) == 0) {
-			return user, errors.Errorf("must provide at least one UID or GID mapping to configure a user namespace")
+	case NoMap:
+		mappings, uid, gid, err := util.GetNoMapMapping()
+		if err != nil {
+			return user, err
 		}
-		for _, uidmap := range idmappings.UIDMap {
-			g.AddLinuxUIDMapping(uint32(uidmap.HostID), uint32(uidmap.ContainerID), uint32(uidmap.Size))
+		idmappings = mappings
+		g.SetProcessUID(uint32(uid))
+		g.SetProcessGID(uint32(gid))
+		user = fmt.Sprintf("%d:%d", uid, gid)
+		if err := privateUserNamespace(idmappings, g); err != nil {
+			return user, err
 		}
-		for _, gidmap := range idmappings.GIDMap {
-			g.AddLinuxGIDMapping(uint32(gidmap.HostID), uint32(gidmap.ContainerID), uint32(gidmap.Size))
+	case Private:
+		if err := privateUserNamespace(idmappings, g); err != nil {
+			return user, err
 		}
 	}
 	return user, nil
 }
+
+func privateUserNamespace(idmappings *storage.IDMappingOptions, g *generate.Generator) error {
+	if err := g.AddOrReplaceLinuxNamespace(string(spec.UserNamespace), ""); err != nil {
+		return err
+	}
+	if idmappings == nil || (len(idmappings.UIDMap) == 0 && len(idmappings.GIDMap) == 0) {
+		return errors.Errorf("must provide at least one UID or GID mapping to configure a user namespace")
+	}
+	for _, uidmap := range idmappings.UIDMap {
+		g.AddLinuxUIDMapping(uint32(uidmap.HostID), uint32(uidmap.ContainerID), uint32(uidmap.Size))
+	}
+	for _, gidmap := range idmappings.GIDMap {
+		g.AddLinuxGIDMapping(uint32(gidmap.HostID), uint32(gidmap.ContainerID), uint32(gidmap.Size))
+	}
+	return nil
+}