github.com/go-xe2/third@v1.0.3/golang.org/x/sys/unix/openbsd_pledge.go (about)

     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  }