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  )
    12  
    13  // Pledge implements the pledge syscall.
    14  //
    15  // This changes both the promises and execpromises; use PledgePromises or
    16  // PledgeExecpromises to only change the promises or execpromises
    17  // respectively.
    18  //
    19  // For more information see pledge(2).
    20  func Pledge(promises, execpromises string) error {
    21  	if err := pledgeAvailable(); err != nil {
    22  		return err
    23  	}
    24  
    25  	pptr, err := BytePtrFromString(promises)
    26  	if err != nil {
    27  		return err
    28  	}
    29  
    30  	exptr, err := BytePtrFromString(execpromises)
    31  	if err != nil {
    32  		return err
    33  	}
    34  
    35  	return pledge(pptr, exptr)
    36  }
    37  
    38  // PledgePromises implements the pledge syscall.
    39  //
    40  // This changes the promises and leaves the execpromises untouched.
    41  //
    42  // For more information see pledge(2).
    43  func PledgePromises(promises string) error {
    44  	if err := pledgeAvailable(); err != nil {
    45  		return err
    46  	}
    47  
    48  	pptr, err := BytePtrFromString(promises)
    49  	if err != nil {
    50  		return err
    51  	}
    52  
    53  	return pledge(pptr, nil)
    54  }
    55  
    56  // PledgeExecpromises implements the pledge syscall.
    57  //
    58  // This changes the execpromises and leaves the promises untouched.
    59  //
    60  // For more information see pledge(2).
    61  func PledgeExecpromises(execpromises string) error {
    62  	if err := pledgeAvailable(); err != nil {
    63  		return err
    64  	}
    65  
    66  	exptr, err := BytePtrFromString(execpromises)
    67  	if err != nil {
    68  		return err
    69  	}
    70  
    71  	return pledge(nil, exptr)
    72  }
    73  
    74  // majmin returns major and minor version number for an OpenBSD system.
    75  func majmin() (major int, minor int, err error) {
    76  	var v Utsname
    77  	err = Uname(&v)
    78  	if err != nil {
    79  		return
    80  	}
    81  
    82  	major, err = strconv.Atoi(string(v.Release[0]))
    83  	if err != nil {
    84  		err = errors.New("cannot parse major version number returned by uname")
    85  		return
    86  	}
    87  
    88  	minor, err = strconv.Atoi(string(v.Release[2]))
    89  	if err != nil {
    90  		err = errors.New("cannot parse minor version number returned by uname")
    91  		return
    92  	}
    93  
    94  	return
    95  }
    96  
    97  // pledgeAvailable checks for availability of the pledge(2) syscall
    98  // based on the running OpenBSD version.
    99  func pledgeAvailable() error {
   100  	maj, min, err := majmin()
   101  	if err != nil {
   102  		return err
   103  	}
   104  
   105  	// Require OpenBSD 6.4 as a minimum.
   106  	if maj < 6 || (maj == 6 && min <= 3) {
   107  		return fmt.Errorf("cannot call Pledge on OpenBSD %d.%d", maj, min)
   108  	}
   109  
   110  	return nil
   111  }
   112
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