diff options
Diffstat (limited to 'pkg/rootless')
| -rw-r--r-- | pkg/rootless/rootless.go | 84 | ||||
| -rw-r--r-- | pkg/rootless/rootless_test.go | 101 |
2 files changed, 185 insertions, 0 deletions
diff --git a/pkg/rootless/rootless.go b/pkg/rootless/rootless.go index 2894c043f..df35c0d6b 100644 --- a/pkg/rootless/rootless.go +++ b/pkg/rootless/rootless.go @@ -2,10 +2,12 @@ package rootless import ( "os" + "sort" "sync" "github.com/containers/storage" "github.com/opencontainers/runc/libcontainer/user" + spec "github.com/opencontainers/runtime-spec/specs-go" "github.com/pkg/errors" ) @@ -87,6 +89,20 @@ func GetAvailableGidMap() ([]user.IDMap, error) { return gidMap, gidMapError } +// GetAvailableIDMaps returns the UID and GID mappings in the +// current user namespace. +func GetAvailableIDMaps() ([]user.IDMap, []user.IDMap, error) { + u, err := GetAvailableUidMap() + if err != nil { + return nil, nil, err + } + g, err := GetAvailableGidMap() + if err != nil { + return nil, nil, err + } + return u, g, nil +} + func countAvailableIDs(mappings []user.IDMap) int64 { availableUids := int64(0) for _, r := range mappings { @@ -116,3 +132,71 @@ func GetAvailableGids() (int64, error) { return countAvailableIDs(gids), nil } + +// findIDInMappings find the the mapping that contains the specified ID. +// It assumes availableMappings is sorted by ID. +func findIDInMappings(id int64, availableMappings []user.IDMap) *user.IDMap { + i := sort.Search(len(availableMappings), func(i int) bool { + return availableMappings[i].ID >= id + }) + if i < 0 || i >= len(availableMappings) { + return nil + } + r := &availableMappings[i] + if id >= r.ID && id < r.ID+r.Count { + return r + } + return nil +} + +// MaybeSplitMappings checks whether the specified OCI mappings are possible +// in the current user namespace or the specified ranges must be split. +func MaybeSplitMappings(mappings []spec.LinuxIDMapping, availableMappings []user.IDMap) []spec.LinuxIDMapping { + var ret []spec.LinuxIDMapping + var overflow spec.LinuxIDMapping + overflow.Size = 0 + consumed := 0 + sort.Slice(availableMappings, func(i, j int) bool { + return availableMappings[i].ID < availableMappings[j].ID + }) + for { + cur := overflow + // if there is no overflow left from the previous request, get the next one + if cur.Size == 0 { + if consumed == len(mappings) { + // all done + return ret + } + cur = mappings[consumed] + consumed++ + } + + // Find the range where the first specified ID is present + r := findIDInMappings(int64(cur.HostID), availableMappings) + if r == nil { + // The requested range is not available. Just return the original request + // and let other layers deal with it. + return mappings + } + + offsetInRange := cur.HostID - uint32(r.ID) + + usableIDs := uint32(r.Count) - offsetInRange + + // the current range can satisfy the whole request + if usableIDs >= cur.Size { + // reset the overflow + overflow.Size = 0 + } else { + // the current range can satisfy the request partially + // so move the rest to overflow + overflow.Size = cur.Size - usableIDs + overflow.ContainerID = cur.ContainerID + usableIDs + overflow.HostID = cur.HostID + usableIDs + + // and cap to the usableIDs count + cur.Size = usableIDs + } + ret = append(ret, cur) + } +} diff --git a/pkg/rootless/rootless_test.go b/pkg/rootless/rootless_test.go new file mode 100644 index 000000000..ef574099c --- /dev/null +++ b/pkg/rootless/rootless_test.go @@ -0,0 +1,101 @@ +package rootless + +import ( + "reflect" + "testing" + + "github.com/opencontainers/runc/libcontainer/user" + spec "github.com/opencontainers/runtime-spec/specs-go" +) + +func TestMaybeSplitMappings(t *testing.T) { + mappings := []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 2, + }, + } + desiredMappings := []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 1, + }, + { + ContainerID: 1, + HostID: 1, + Size: 1, + }, + } + availableMappings := []user.IDMap{ + { + ID: 1, + ParentID: 1000000, + Count: 65536, + }, + { + ID: 0, + ParentID: 1000, + Count: 1, + }, + } + newMappings := MaybeSplitMappings(mappings, availableMappings) + if !reflect.DeepEqual(newMappings, desiredMappings) { + t.Fatal("wrong mappings generated") + } + + mappings = []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 2, + }, + } + desiredMappings = []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 2, + }, + } + availableMappings = []user.IDMap{ + { + ID: 0, + ParentID: 1000000, + Count: 65536, + }, + } + newMappings = MaybeSplitMappings(mappings, availableMappings) + + if !reflect.DeepEqual(newMappings, desiredMappings) { + t.Fatal("wrong mappings generated") + } + + mappings = []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 1, + }, + } + desiredMappings = []spec.LinuxIDMapping{ + { + ContainerID: 0, + HostID: 0, + Size: 1, + }, + } + availableMappings = []user.IDMap{ + { + ID: 10000, + ParentID: 10000, + Count: 65536, + }, + } + + newMappings = MaybeSplitMappings(mappings, availableMappings) + if !reflect.DeepEqual(newMappings, desiredMappings) { + t.Fatal("wrong mappings generated") + } +} |