94 lines
2.2 KiB
Go
94 lines
2.2 KiB
Go
//go:build (linux || darwin) && !cgo
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// +build linux darwin
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// +build !cgo
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/*
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Copyright 2020 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package util
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import (
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"bufio"
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"bytes"
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"io"
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"os"
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"os/user"
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"strconv"
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"strings"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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)
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var groupFile = "/etc/group"
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type group struct {
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id string // group ID
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name string // group name
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members []string // secondary group ids
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}
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// groupIDs returns all of the group ID's a user is a member of
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func groupIDs(u *user.User) ([]string, error) {
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logrus.Infof("Performing slow lookup of group ids for %s", u.Username)
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f, err := os.Open(groupFile)
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if err != nil {
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return nil, errors.Wrap(err, "open")
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}
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defer f.Close()
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gids := []string{u.Gid}
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for _, g := range localGroups(f) {
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for _, m := range g.members {
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if m == u.Username {
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gids = append(gids, g.id)
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}
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}
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}
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return gids, nil
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}
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// localGroups parses a reader in /etc/group form, returning parsed group data
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// based on src/os/user/lookup_unix.go - but extended to include secondary groups
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func localGroups(r io.Reader) []*group {
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var groups []*group
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bs := bufio.NewScanner(r)
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for bs.Scan() {
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line := bs.Bytes()
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// There's no spec for /etc/passwd or /etc/group, but we try to follow
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// the same rules as the glibc parser, which allows comments and blank
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// space at the beginning of a line.
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line = bytes.TrimSpace(line)
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if len(line) == 0 || line[0] == '#' {
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continue
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}
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// wheel:*:0:root,anotherGrp
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parts := strings.SplitN(string(line), ":", 4)
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if _, err := strconv.Atoi(parts[2]); err != nil {
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continue
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}
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groups = append(groups, &group{name: parts[0], id: parts[2], members: strings.Split(parts[3], ",")})
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}
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return groups
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}
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