buildkit/executor/oci/user.go

100 lines
2.5 KiB
Go

package oci
import (
"context"
"errors"
"os"
"strconv"
"strings"
"github.com/containerd/containerd/containers"
containerdoci "github.com/containerd/containerd/oci"
"github.com/containerd/continuity/fs"
"github.com/opencontainers/runc/libcontainer/user"
"github.com/opencontainers/runtime-spec/specs-go"
)
func GetUser(ctx context.Context, root, username string) (uint32, uint32, []uint32, error) {
// fast path from uid/gid
if uid, gid, err := ParseUIDGID(username); err == nil {
return uid, gid, nil, nil
}
passwdFile, err := openUserFile(root, "/etc/passwd")
if err == nil {
defer passwdFile.Close()
}
groupFile, err := openUserFile(root, "/etc/group")
if err == nil {
defer groupFile.Close()
}
execUser, err := user.GetExecUser(username, nil, passwdFile, groupFile)
if err != nil {
return 0, 0, nil, err
}
var sgids []uint32
for _, g := range execUser.Sgids {
sgids = append(sgids, uint32(g))
}
return uint32(execUser.Uid), uint32(execUser.Gid), sgids, nil
}
// ParseUIDGID takes the fast path to parse UID and GID if and only if they are both provided
func ParseUIDGID(str string) (uid uint32, gid uint32, err error) {
if str == "" {
return 0, 0, nil
}
parts := strings.SplitN(str, ":", 2)
if len(parts) == 1 {
return 0, 0, errors.New("groups ID is not provided")
}
if uid, err = parseUID(parts[0]); err != nil {
return 0, 0, err
}
if gid, err = parseUID(parts[1]); err != nil {
return 0, 0, err
}
return
}
func openUserFile(root, p string) (*os.File, error) {
p, err := fs.RootPath(root, p)
if err != nil {
return nil, err
}
return os.Open(p)
}
func parseUID(str string) (uint32, error) {
if str == "root" {
return 0, nil
}
uid, err := strconv.ParseUint(str, 10, 32)
if err != nil {
return 0, err
}
return uint32(uid), nil
}
// WithUIDGID allows the UID and GID for the Process to be set
// FIXME: This is a temporeray fix for the missing supplementary GIDs from containerd
// once the PR in containerd is merged we should remove this function.
func WithUIDGID(uid, gid uint32, sgids []uint32) containerdoci.SpecOpts {
return func(_ context.Context, _ containerdoci.Client, _ *containers.Container, s *containerdoci.Spec) error {
setProcess(s)
s.Process.User.UID = uid
s.Process.User.GID = gid
s.Process.User.AdditionalGids = sgids
return nil
}
}
// setProcess sets Process to empty if unset
// FIXME: Same on this one. Need to be removed after containerd fix merged
func setProcess(s *containerdoci.Spec) {
if s.Process == nil {
s.Process = &specs.Process{}
}
}