Merge pull request #7882 from giuseppe/check-for-gids-before-adding-them

libpod: check there are enough gids before adding them

2 files changed, 26 insertions, 14 deletions

diff --git a/pkg/rootless/rootless.go b/pkg/rootless/rootless.go
index d02721ea9..799c793d8 100644
--- a/pkg/rootless/rootless.go
+++ b/pkg/rootless/rootless.go
@@ -2,8 +2,10 @@ package rootless
 
 import (
 	"os"
+	"sync"
 
 	"github.com/containers/storage"
+	"github.com/opencontainers/runc/libcontainer/user"
 	"github.com/pkg/errors"
 )
 
@@ -46,3 +48,26 @@ func TryJoinPauseProcess(pausePidPath string) (bool, int, error) {
 	}
 	return became, ret, err
 }
+
+var (
+	availableGids     int64
+	availableGidsErr  error
+	availableGidsOnce sync.Once
+)
+
+// GetAvailableGids returns how many GIDs are available in the
+// current user namespace.
+func GetAvailableGids() (int64, error) {
+	availableGidsOnce.Do(func() {
+		idMap, err := user.ParseIDMapFile("/proc/self/gid_map")
+		if err != nil {
+			availableGidsErr = err
+			return
+		}
+		availableGids = int64(0)
+		for _, r := range idMap {
+			availableGids += r.Count
+		}
+	})
+	return availableGids, availableGidsErr
+}
diff --git a/pkg/specgen/generate/oci.go b/pkg/specgen/generate/oci.go
index b57ddf1aa..f02432f5b 100644
--- a/pkg/specgen/generate/oci.go
+++ b/pkg/specgen/generate/oci.go
@@ -10,7 +10,6 @@ import (
 	"github.com/containers/podman/v2/libpod/image"
 	"github.com/containers/podman/v2/pkg/rootless"
 	"github.com/containers/podman/v2/pkg/specgen"
-	"github.com/opencontainers/runc/libcontainer/user"
 	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/opencontainers/runtime-tools/generate"
 	"github.com/pkg/errors"
@@ -200,7 +199,7 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
 	}
 	gid5Available := true
 	if isRootless {
-		nGids, err := GetAvailableGids()
+		nGids, err := rootless.GetAvailableGids()
 		if err != nil {
 			return nil, err
 		}
@@ -360,15 +359,3 @@ func SpecGenToOCI(ctx context.Context, s *specgen.SpecGenerator, rt *libpod.Runt
 
 	return configSpec, nil
 }
-
-func GetAvailableGids() (int64, error) {
-	idMap, err := user.ParseIDMapFile("/proc/self/gid_map")
-	if err != nil {
-		return 0, err
-	}
-	count := int64(0)
-	for _, r := range idMap {
-		count += r.Count
-	}
-	return count, nil
-}