rand_linux_test.go

     1  // Copyright 2024 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  //go:build cgo
     6  
     7  package sysrand_test
     8  
     9  import (
    10  	"bytes"
    11  	"crypto/internal/sysrand/internal/seccomp"
    12  	"internal/syscall/unix"
    13  	"internal/testenv"
    14  	"os"
    15  	"runtime"
    16  	"syscall"
    17  	"testing"
    18  )
    19  
    20  func TestNoGetrandom(t *testing.T) {
    21  	if os.Getenv("GO_GETRANDOM_DISABLED") == "1" {
    22  		// We are running under seccomp, the rest of the test suite will take
    23  		// care of actually testing the implementation, we check that getrandom
    24  		// is actually disabled.
    25  		_, err := unix.GetRandom(make([]byte, 16), 0)
    26  		if err != syscall.ENOSYS {
    27  			t.Errorf("GetRandom returned %v, want ENOSYS", err)
    28  		} else {
    29  			t.Log("GetRandom returned ENOSYS as expected")
    30  		}
    31  		return
    32  	}
    33  
    34  	if testing.Short() {
    35  		t.Skip("skipping test in short mode")
    36  	}
    37  	testenv.MustHaveExec(t) // testenv.Command can't skip from a goroutine
    38  
    39  	done := make(chan struct{})
    40  	go func() {
    41  		defer close(done)
    42  		// Call LockOSThread in a new goroutine, where we will apply the seccomp
    43  		// filter. We exit without unlocking the thread, so the thread will die
    44  		// and won't be reused.
    45  		runtime.LockOSThread()
    46  
    47  		if err := seccomp.DisableGetrandom(); err != nil {
    48  			t.Errorf("failed to disable getrandom: %v", err)
    49  			return
    50  		}
    51  
    52  		cmd := testenv.Command(t, testenv.Executable(t), "-test.v")
    53  		cmd.Env = append(os.Environ(), "GO_GETRANDOM_DISABLED=1")
    54  		out, err := cmd.CombinedOutput()
    55  		t.Logf("running with GO_GETRANDOM_DISABLED=1:\n%s", out)
    56  		if err != nil {
    57  			t.Errorf("subprocess failed: %v", err)
    58  			return
    59  		}
    60  
    61  		if !bytes.Contains(out, []byte("GetRandom returned ENOSYS")) {
    62  			t.Errorf("subprocess did not disable getrandom")
    63  		}
    64  		if !bytes.Contains(out, []byte("TestRead")) {
    65  			t.Errorf("subprocess did not run TestRead")
    66  		}
    67  	}()
    68  	<-done
    69  }
    70
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