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

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