mirror of
https://github.com/cwinfo/yggdrasil-go.git
synced 2024-12-23 00:35:39 +00:00
75d2080e53
Changing the real and effective user/group IDs and the saved set-user/group-ID is not enough to get rid of intial access permissions. The list of groups must be cleared also, otherwise a process changing from, e.g. `root:root` to `nobody:nobody` retains rights to access `:wheel` files (assuming `root` is a member of the `wheel` group). For example: ``` # id uid=0(root) gid=0(wheel) groups=0(wheel), 2(kmem), 3(sys), 4(tty), 5(operator), 20(staff), 31(guest) # ./yggdrasil -autoconf -logto /dev/null -user nobody & [1] 4337 # ps -o command,user,group,supgrp -U nobody COMMAND USER GROUP SUPGRP ./yggdrasil -aut nobody nobody wheel,kmem,sys,tty,operator,staff,guest ``` Fix that so the process runs as mere ``` COMMAND USER GROUP SUPGRP ./yggdrasil -aut nobody nobody nobody ``` Fixes #927.
94 lines
2.1 KiB
Go
94 lines
2.1 KiB
Go
//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
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// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
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package main
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import (
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"errors"
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"fmt"
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"math"
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osuser "os/user"
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"strconv"
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"strings"
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"syscall"
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)
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func chuser(user string) error {
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group := ""
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if i := strings.IndexByte(user, ':'); i >= 0 {
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user, group = user[:i], user[i+1:]
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}
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u := (*osuser.User)(nil)
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g := (*osuser.Group)(nil)
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if user != "" {
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if _, err := strconv.ParseUint(user, 10, 32); err == nil {
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u, err = osuser.LookupId(user)
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if err != nil {
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return fmt.Errorf("failed to lookup user by id %q: %v", user, err)
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}
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} else {
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u, err = osuser.Lookup(user)
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if err != nil {
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return fmt.Errorf("failed to lookup user by name %q: %v", user, err)
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}
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}
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}
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if group != "" {
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if _, err := strconv.ParseUint(group, 10, 32); err == nil {
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g, err = osuser.LookupGroupId(group)
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if err != nil {
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return fmt.Errorf("failed to lookup group by id %q: %v", user, err)
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}
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} else {
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g, err = osuser.LookupGroup(group)
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if err != nil {
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return fmt.Errorf("failed to lookup group by name %q: %v", user, err)
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}
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}
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}
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if g != nil {
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gid, _ := strconv.ParseUint(g.Gid, 10, 32)
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var err error
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if gid < math.MaxInt {
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if err := syscall.Setgroups([]int{int(gid)}); err != nil {
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return fmt.Errorf("failed to setgroups %d: %v", gid, err)
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}
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err = syscall.Setgid(int(gid))
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} else {
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err = errors.New("gid too big")
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}
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if err != nil {
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return fmt.Errorf("failed to setgid %d: %v", gid, err)
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}
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} else if u != nil {
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gid, _ := strconv.ParseUint(u.Gid, 10, 32)
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if err := syscall.Setgroups([]int{int(uint32(gid))}); err != nil {
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return fmt.Errorf("failed to setgroups %d: %v", gid, err)
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}
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err := syscall.Setgid(int(uint32(gid)))
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if err != nil {
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return fmt.Errorf("failed to setgid %d: %v", gid, err)
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}
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}
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if u != nil {
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uid, _ := strconv.ParseUint(u.Uid, 10, 32)
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var err error
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if uid < math.MaxInt {
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err = syscall.Setuid(int(uid))
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} else {
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err = errors.New("uid too big")
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}
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if err != nil {
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return fmt.Errorf("failed to setuid %d: %v", uid, err)
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}
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}
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return nil
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}
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