mirror of
https://tildegit.org/solderpunk/molly-brown
synced 2024-05-13 04:26:03 +02:00
212c9f79fb
Basically the function formerly known as do_main() in main.go has been renamed launch() and moved into launch.go. Now there are main.go and main_unix.go files implementing minmial main() functions which load a config and pass it to launch. This allows separating unix-specific security stuff (both the actual system calls which won't compile on other platforms and the definition of command line switches) out from the platform agnostic implementation of the main server logic. It also simplifies the interaction of relative paths in config files with chrooting. Docs still need updating...
122 lines
2.6 KiB
Go
122 lines
2.6 KiB
Go
// +build linux,go1.16 aix darwin dragonfly freebsd illumos netbsd openbsd solaris
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package main
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import (
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"log"
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"os"
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"os/user"
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"strconv"
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"syscall"
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)
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type userInfo struct {
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uid int
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euid int
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gid int
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egid int
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supp_groups []int
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is_setuid bool
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is_setgid bool
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root_user bool
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root_prim_group bool
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root_supp_group bool
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need_drop bool
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unpriv_uid int
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unpriv_gid int
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}
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func getUserInfo(unprivUser string) (userInfo, error) {
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var ui userInfo
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ui.uid = os.Getuid()
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ui.euid = os.Geteuid()
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ui.gid = os.Getgid()
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ui.egid = os.Getegid()
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supp_groups, err := os.Getgroups()
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if err != nil {
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log.Println("Could not get supplementary groups: ", err.Error())
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return ui, err
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}
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ui.supp_groups = supp_groups
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ui.unpriv_uid = -1
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ui.unpriv_gid = -1
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ui.is_setuid = ui.uid != ui.euid
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ui.is_setgid = ui.gid != ui.egid
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ui.root_user = ui.uid == 0 || ui.euid == 0
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ui.root_prim_group = ui.gid == 0 || ui.egid == 0
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for _, gid := range ui.supp_groups {
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if gid == 0 {
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ui.root_supp_group = true
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break
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}
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}
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ui.need_drop = ui.is_setuid || ui.is_setgid || ui.root_user || ui.root_prim_group || ui.root_supp_group
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if ui.root_user || ui.root_prim_group {
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nobody_user, err := user.Lookup(unprivUser)
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if err != nil {
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log.Println("Running as root but could not lookup UID for user " + unprivUser + ": " + err.Error())
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return ui, err
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}
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ui.unpriv_uid, err = strconv.Atoi(nobody_user.Uid)
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ui.unpriv_gid, err = strconv.Atoi(nobody_user.Gid)
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if err != nil {
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log.Println("Running as root but could not lookup UID for user " + unprivUser + ": " + err.Error())
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return ui, err
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}
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}
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return ui, nil
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}
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func DropPrivs(ui userInfo) error {
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// If we're already unprivileged, all good
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if !ui.need_drop {
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return nil
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}
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// Drop supplementary groups
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err := syscall.Setgroups([]int{})
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if err != nil {
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// Log failure
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log.Println("Could not unset supplementary groups: " + err.Error())
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// Make this fatal if root was amongst supplementary groups
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if ui.root_supp_group {
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return err
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}
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}
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// Setgid()
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if ui.root_prim_group || ui.is_setgid {
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var target_gid int
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if ui.root_prim_group {
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target_gid = ui.unpriv_gid
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} else {
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target_gid = ui.gid
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}
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err := syscall.Setgid(target_gid)
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if err != nil {
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log.Println("Could not setgid to " + strconv.Itoa(target_gid) + ": " + err.Error())
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return err
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}
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}
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// Setuid()
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if ui.root_user || ui.is_setuid {
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var target_uid int
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if ui.root_user {
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target_uid = ui.unpriv_uid
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} else {
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target_uid = ui.uid
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}
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err := syscall.Setuid(target_uid)
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if err != nil {
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log.Println("Could not setuid to " + strconv.Itoa(target_uid) + ": " + err.Error())
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return err
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}
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}
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return nil
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}
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