From f09370c68b8b514aca80bfaa34f98fbc5b97d318 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Thu, 23 May 2019 22:28:59 +0200 Subject: [PATCH] userns: add new option --userns=keep-id it creates a namespace where the current UID:GID on the host is mapped to the same UID:GID in the container. Signed-off-by: Giuseppe Scrivano --- cmd/podman/libpodruntime/runtime.go | 4 ++- cmd/podman/shared/create.go | 7 ++-- docs/podman-create.1.md | 2 ++ docs/podman-run.1.md | 2 ++ pkg/namespaces/namespaces.go | 7 +++- pkg/util/utils.go | 53 ++++++++++++++++++++++++++++- test/e2e/run_userns_test.go | 9 +++++ 7 files changed, 79 insertions(+), 5 deletions(-) diff --git a/cmd/podman/libpodruntime/runtime.go b/cmd/podman/libpodruntime/runtime.go index b8d77602d702..898c81515adc 100644 --- a/cmd/podman/libpodruntime/runtime.go +++ b/cmd/podman/libpodruntime/runtime.go @@ -5,6 +5,7 @@ import ( "github.com/containers/libpod/cmd/podman/cliconfig" "github.com/containers/libpod/libpod" + "github.com/containers/libpod/pkg/namespaces" "github.com/containers/libpod/pkg/rootless" "github.com/containers/libpod/pkg/util" "github.com/containers/storage" @@ -37,11 +38,12 @@ func getRuntime(ctx context.Context, c *cliconfig.PodmanCommand, renumber bool, subgidname := c.Flags().Lookup("subgidname") if (uidmapFlag != nil && gidmapFlag != nil && subuidname != nil && subgidname != nil) && (uidmapFlag.Changed || gidmapFlag.Changed || subuidname.Changed || subgidname.Changed) { + userns, _ := c.Flags().GetString("userns") uidmapVal, _ := c.Flags().GetStringSlice("uidmap") gidmapVal, _ := c.Flags().GetStringSlice("gidmap") subuidVal, _ := c.Flags().GetString("subuidname") subgidVal, _ := c.Flags().GetString("subgidname") - mappings, err := util.ParseIDMapping(uidmapVal, gidmapVal, subuidVal, subgidVal) + mappings, err := util.ParseIDMapping(namespaces.UsernsMode(userns), uidmapVal, gidmapVal, subuidVal, subgidVal) if err != nil { return nil, err } diff --git a/cmd/podman/shared/create.go b/cmd/podman/shared/create.go index d1f704374ec5..3c9b178043bc 100644 --- a/cmd/podman/shared/create.go +++ b/cmd/podman/shared/create.go @@ -19,6 +19,7 @@ import ( ann "github.com/containers/libpod/pkg/annotations" "github.com/containers/libpod/pkg/inspect" ns "github.com/containers/libpod/pkg/namespaces" + "github.com/containers/libpod/pkg/rootless" cc "github.com/containers/libpod/pkg/spec" "github.com/containers/libpod/pkg/util" "github.com/docker/docker/pkg/signal" @@ -283,7 +284,7 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod. namespaces map[string]string ) - idmappings, err := util.ParseIDMapping(c.StringSlice("uidmap"), c.StringSlice("gidmap"), c.String("subuidname"), c.String("subgidname")) + idmappings, err := util.ParseIDMapping(ns.UsernsMode(c.String("userns")), c.StringSlice("uidmap"), c.StringSlice("gidmap"), c.String("subuidname"), c.String("subgidname")) if err != nil { return nil, err } @@ -451,7 +452,9 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod. // USER user := c.String("user") if user == "" { - if data == nil { + if usernsMode.IsKeepID() { + user = fmt.Sprintf("%d:%d", rootless.GetRootlessUID(), rootless.GetRootlessGID()) + } else if data == nil { user = "0" } else { user = data.Config.User diff --git a/docs/podman-create.1.md b/docs/podman-create.1.md index 58e579605f60..53f4c8fed5b7 100644 --- a/docs/podman-create.1.md +++ b/docs/podman-create.1.md @@ -727,11 +727,13 @@ The followings examples are all valid: Without this argument the command will be run as root in the container. **--userns**=host +**--userns**=keep-id **--userns**=ns:my_namespace Set the user namespace mode for the container. The use of userns is disabled by default. - `host`: run in the user namespace of the caller. This is the default if no user namespace options are set. The processes running in the container will have the same privileges on the host as any other process launched by the calling user. +- `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. - `ns`: run the container in the given existing user namespace. This option is incompatible with --gidmap, --uidmap, --subuid and --subgid diff --git a/docs/podman-run.1.md b/docs/podman-run.1.md index a9484a517d3a..95e99cb7ef8e 100644 --- a/docs/podman-run.1.md +++ b/docs/podman-run.1.md @@ -763,11 +763,13 @@ The followings examples are all valid: Without this argument the command will be run as root in the container. **--userns**=host +**--userns**=keep-id **--userns**=ns:my_namespace Set the user namespace mode for the container. The use of userns is disabled by default. - `host`: run in the user namespace of the caller. This is the default if no user namespace options are set. The processes running in the container will have the same privileges on the host as any other process launched by the calling user. +- `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. - `ns`: run the container in the given existing user namespace. This option is incompatible with --gidmap, --uidmap, --subuid and --subgid diff --git a/pkg/namespaces/namespaces.go b/pkg/namespaces/namespaces.go index fde6118af2f5..ec9276344017 100644 --- a/pkg/namespaces/namespaces.go +++ b/pkg/namespaces/namespaces.go @@ -12,6 +12,11 @@ func (n UsernsMode) IsHost() bool { return n == "host" } +// IsKeepID indicates whether container uses a mapping where the (uid, gid) on the host is lept inside of the namespace. +func (n UsernsMode) IsKeepID() bool { + return n == "keep-id" +} + // IsPrivate indicates whether the container uses the a private userns. func (n UsernsMode) IsPrivate() bool { return !(n.IsHost()) @@ -21,7 +26,7 @@ func (n UsernsMode) IsPrivate() bool { func (n UsernsMode) Valid() bool { parts := strings.Split(string(n), ":") switch mode := parts[0]; mode { - case "", "host": + case "", "host", "keep-id": default: return false } diff --git a/pkg/util/utils.go b/pkg/util/utils.go index 2a52e5129b6d..a074f276cc18 100644 --- a/pkg/util/utils.go +++ b/pkg/util/utils.go @@ -3,6 +3,7 @@ package util import ( "fmt" "os" + ouser "os/user" "path/filepath" "strings" "sync" @@ -11,6 +12,8 @@ import ( "github.com/BurntSushi/toml" "github.com/containers/image/types" "github.com/containers/libpod/cmd/podman/cliconfig" + "github.com/containers/libpod/pkg/namespaces" + "github.com/containers/libpod/pkg/rootless" "github.com/containers/storage" "github.com/containers/storage/pkg/idtools" "github.com/opencontainers/image-spec/specs-go/v1" @@ -131,11 +134,59 @@ func GetImageConfig(changes []string) (v1.ImageConfig, error) { } // ParseIDMapping takes idmappings and subuid and subgid maps and returns a storage mapping -func ParseIDMapping(UIDMapSlice, GIDMapSlice []string, subUIDMap, subGIDMap string) (*storage.IDMappingOptions, error) { +func ParseIDMapping(mode namespaces.UsernsMode, UIDMapSlice, GIDMapSlice []string, subUIDMap, subGIDMap string) (*storage.IDMappingOptions, error) { options := storage.IDMappingOptions{ HostUIDMapping: true, HostGIDMapping: true, } + + if mode.IsKeepID() { + if len(UIDMapSlice) > 0 || len(GIDMapSlice) > 0 { + return nil, errors.New("cannot specify custom mappings with --userns=keep-id") + } + if len(subUIDMap) > 0 || len(subGIDMap) > 0 { + return nil, errors.New("cannot specify subuidmap or subgidmap with --userns=keep-id") + } + if rootless.IsRootless() { + uid := rootless.GetRootlessUID() + gid := rootless.GetRootlessGID() + + username := os.Getenv("USER") + if username == "" { + user, err := ouser.LookupId(fmt.Sprintf("%d", uid)) + if err == nil { + username = user.Username + } + } + mappings, err := idtools.NewIDMappings(username, username) + if err != nil { + return nil, errors.Wrapf(err, "cannot find mappings for user %s", username) + } + maxUID, maxGID := 0, 0 + for _, u := range mappings.UIDs() { + maxUID += u.Size + } + for _, g := range mappings.GIDs() { + maxGID += g.Size + } + + options.UIDMap, options.GIDMap = nil, nil + + options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: uid}) + options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid, HostID: 0, Size: 1}) + options.UIDMap = append(options.UIDMap, idtools.IDMap{ContainerID: uid + 1, HostID: uid + 1, Size: maxUID - uid}) + + options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: 0, HostID: 1, Size: gid}) + options.GIDMap = append(options.GIDMap, idtools.IDMap{ContainerID: gid, HostID: 0, Size: 1}) + 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 + } + if subGIDMap == "" && subUIDMap != "" { subGIDMap = subUIDMap } diff --git a/test/e2e/run_userns_test.go b/test/e2e/run_userns_test.go index f7f0e1c9a43a..ce6971cd1d80 100644 --- a/test/e2e/run_userns_test.go +++ b/test/e2e/run_userns_test.go @@ -3,6 +3,7 @@ package integration import ( + "fmt" "os" . "github.com/containers/libpod/test/utils" @@ -76,4 +77,12 @@ var _ = Describe("Podman UserNS support", func() { Expect(ok).To(BeTrue()) }) + It("podman --userns=keep-id", func() { + session := podmanTest.Podman([]string{"run", "--userns=keep-id", "alpine", "id", "-u"}) + session.WaitWithDefaultTimeout() + Expect(session.ExitCode()).To(Equal(0)) + uid := fmt.Sprintf("%d", os.Geteuid()) + ok, _ := session.GrepString(uid) + Expect(ok).To(BeTrue()) + }) })