vendor/golang.org/x/sys/unix/openbsd_pledge.go

   1 // Copyright 2016 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build openbsd
   6 // +build 386 amd64 arm
   7
   8 package unix
   9
  10 import (
  11         "errors"
  12         "fmt"
  13         "strconv"
  14         "syscall"
  15         "unsafe"
  16 )
  17
  18 // Pledge implements the pledge syscall.
  19 //
  20 // The pledge syscall does not accept execpromises on OpenBSD releases
  21 // before 6.3.
  22 //
  23 // execpromises must be empty when Pledge is called on OpenBSD
  24 // releases predating 6.3, otherwise an error will be returned.
  25 //
  26 // For more information see pledge(2).
  27 func Pledge(promises, execpromises string) error {
  28         maj, min, err := majmin()
  29         if err != nil {
  30                 return err
  31         }
  32
  33         err = pledgeAvailable(maj, min, execpromises)
  34         if err != nil {
  35                 return err
  36         }
  37
  38         pptr, err := syscall.BytePtrFromString(promises)
  39         if err != nil {
  40                 return err
  41         }
  42
  43         // This variable will hold either a nil unsafe.Pointer or
  44         // an unsafe.Pointer to a string (execpromises).
  45         var expr unsafe.Pointer
  46
  47         // If we're running on OpenBSD > 6.2, pass execpromises to the syscall.
  48         if maj > 6 || (maj == 6 && min > 2) {
  49                 exptr, err := syscall.BytePtrFromString(execpromises)
  50                 if err != nil {
  51                         return err
  52                 }
  53                 expr = unsafe.Pointer(exptr)
  54         }
  55
  56         _, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)), uintptr(expr), 0)
  57         if e != 0 {
  58                 return e
  59         }
  60
  61         return nil
  62 }
  63
  64 // PledgePromises implements the pledge syscall.
  65 //
  66 // This changes the promises and leaves the execpromises untouched.
  67 //
  68 // For more information see pledge(2).
  69 func PledgePromises(promises string) error {
  70         maj, min, err := majmin()
  71         if err != nil {
  72                 return err
  73         }
  74
  75         err = pledgeAvailable(maj, min, "")
  76         if err != nil {
  77                 return err
  78         }
  79
  80         // This variable holds the execpromises and is always nil.
  81         var expr unsafe.Pointer
  82
  83         pptr, err := syscall.BytePtrFromString(promises)
  84         if err != nil {
  85                 return err
  86         }
  87
  88         _, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)), uintptr(expr), 0)
  89         if e != 0 {
  90                 return e
  91         }
  92
  93         return nil
  94 }
  95
  96 // PledgeExecpromises implements the pledge syscall.
  97 //
  98 // This changes the execpromises and leaves the promises untouched.
  99 //
 100 // For more information see pledge(2).
 101 func PledgeExecpromises(execpromises string) error {
 102         maj, min, err := majmin()
 103         if err != nil {
 104                 return err
 105         }
 106
 107         err = pledgeAvailable(maj, min, execpromises)
 108         if err != nil {
 109                 return err
 110         }
 111
 112         // This variable holds the promises and is always nil.
 113         var pptr unsafe.Pointer
 114
 115         exptr, err := syscall.BytePtrFromString(execpromises)
 116         if err != nil {
 117                 return err
 118         }
 119
 120         _, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(pptr), uintptr(unsafe.Pointer(exptr)), 0)
 121         if e != 0 {
 122                 return e
 123         }
 124
 125         return nil
 126 }
 127
 128 // majmin returns major and minor version number for an OpenBSD system.
 129 func majmin() (major int, minor int, err error) {
 130         var v Utsname
 131         err = Uname(&v)
 132         if err != nil {
 133                 return
 134         }
 135
 136         major, err = strconv.Atoi(string(v.Release[0]))
 137         if err != nil {
 138                 err = errors.New("cannot parse major version number returned by uname")
 139                 return
 140         }
 141
 142         minor, err = strconv.Atoi(string(v.Release[2]))
 143         if err != nil {
 144                 err = errors.New("cannot parse minor version number returned by uname")
 145                 return
 146         }
 147
 148         return
 149 }
 150
 151 // pledgeAvailable checks for availability of the pledge(2) syscall
 152 // based on the running OpenBSD version.
 153 func pledgeAvailable(maj, min int, execpromises string) error {
 154         // If OpenBSD <= 5.9, pledge is not available.
 155         if (maj == 5 && min != 9) || maj < 5 {
 156                 return fmt.Errorf("pledge syscall is not available on OpenBSD %d.%d", maj, min)
 157         }
 158
 159         // If OpenBSD <= 6.2 and execpromises is not empty,
 160         // return an error - execpromises is not available before 6.3
 161         if (maj < 6 || (maj == 6 && min <= 2)) && execpromises != "" {
 162                 return fmt.Errorf("cannot use execpromises on OpenBSD %d.%d", maj, min)
 163         }
 164
 165         return nil
 166 }