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Add automatic support for p11-kit #260

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merged 8 commits into from
Jun 12, 2023
Merged

Add automatic support for p11-kit #260

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2723a8f
Add automatic support for p11-kit
maraino Jun 8, 2023
237a370
Mock findP11KitProxy on New test
maraino Jun 8, 2023
1e80f66
Rely on dlopen to locate p11-kit-proxy.so
maraino Jun 8, 2023
bc3ba29
Fix missing-module test
maraino Jun 8, 2023
a23378d
Add p11-kit-proxy.dll for windows and validate uri
maraino Jun 9, 2023
f840799
Add some docs on the pkcs11 kms
maraino Jun 9, 2023
8d82ef2
Add tests and examples with id with %
maraino Jun 9, 2023
572bfb7
Apply suggestions from code review
maraino Jun 12, 2023
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41 changes: 40 additions & 1 deletion kms/pkcs11/pkcs11.go
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Original file line number Diff line number Diff line change
Expand Up @@ -12,11 +12,17 @@ import (
"encoding/hex"
"fmt"
"math/big"
"os"
"os/exec"
"runtime"
"strconv"
"strings"
"sync"
"time"

"github.com/ThalesIgnite/crypto11"
"github.com/pkg/errors"

"go.step.sm/crypto/kms/apiv1"
"go.step.sm/crypto/kms/uri"
)
Expand Down Expand Up @@ -60,7 +66,6 @@ func New(ctx context.Context, opts apiv1.Options) (*PKCS11, error) {
}

config.Pin = u.Pin()
config.Path = u.Get("module-path")
config.TokenLabel = u.Get("token")
config.TokenSerial = u.Get("serial")
if v := u.Get("slot-id"); v != "" {
Expand All @@ -70,6 +75,10 @@ func New(ctx context.Context, opts apiv1.Options) (*PKCS11, error) {
}
config.SlotNumber = &n
}
// Get module or default to use p11-kit-proxy.so
if config.Path = u.Get("module-path"); config.Path == "" {
config.Path = findP11KitProxy(ctx)
}
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This is in the wrong place, isn't it? It'll only happen if a URI is given, but there's an alternative code flow where it's all in the config? That should benefit from the default, too.

There's already a check for config.Path == "" a few lines further down, with an error return which is no longer telling the truth because it says that 'module-path is required'.

Also... what's wrong with pkcs11:manufacturer=piv_II;id=%01 which I usually use as my examples in documentation? Why are only token/serial/slot-id accepted, and not model/manufacturer?

(And why is this something you even need to do for yourself; surely "match token against the attributes in a URI" is a generic thing that ought to be somewhere much further down the stack than your code; in ThalesIgnite/crypto11 or miekg/pkcs11. Ideally you just want to call a function like the matchSlots() I wrote here, and in your case as discussed, you want to just bail if len(slots) != 1).

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I'd still like to see the documentation at least mention that in a properly configured system, module-path should be unnecessary.

In particular, these two:

.. especially the former. I don't want to live in a world where we have to tell users to explicitly pass a module-path.

All those examples for how to use different HSMs differ mostly in the module-path, which shouldn't be needed anyway.

The packaging of the PKCS#11 provider module itself should come with a p11-kit .module file, the token should automatically appear in the output of things like p11-kit list-tokens or p11tool --list-tokens (and thus also in GUIs when you're selecting a client cert for 802.1x or VPN auth, etc.)

The common case is that user should just be able to select a token from the list, e.g. pkcs11:manufacturer=piv_II.

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This is in the wrong place, isn't it? It'll only happen if a URI is given, but there's an alternative code flow where it's all in the config? That should benefit from the default, too.

PKCS#11 cannot be configured without a URI, currently you will get the following error:

return nil, errors.New("kms uri 'module-path' are required")

We can make it more explicit and actually fail if URI == "".

Also... what's wrong with pkcs11:manufacturer=piv_II;id=%01 which I usually use as my examples in documentation? Why are only token/serial/slot-id accepted, and not model/manufacturer?

Nothing, but https://github.com/ThalesIgnite/crypto11, which is the one we use on top of github.com/miekg/pkcs11 doesn't support it, see this code.

Regarding the documentation, some of it is managed by a different team, and we haven't integrated this yet, so it will have to wait a bit. But I can change step-kms-plugin README and help once this is integrated.

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I've fixed some of this in a23378d

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Nothing, but https://github.com/ThalesIgnite/crypto11, which is the one we use on top of github.com/miekg/pkcs11 doesn't support it, see this code.

Thanks. I've added that specific reference to ThalesGroup/crypto11#104

}
if config.Pin == "" && opts.Pin != "" {
config.Pin = opts.Pin
Expand Down Expand Up @@ -402,4 +411,34 @@ func findCertificate(ctx P11, rawuri string) (*x509.Certificate, error) {
return cert, nil
}

// findP11KitProxy uses pkg-config to locate p11-kit-proxy.so
var findP11KitProxy = func(ctx context.Context) string {
var out strings.Builder

// It should be more than enough even in constraint VMs
ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
defer cancel()

cmd := exec.CommandContext(ctx, "pkg-config", "--variable=proxy_module", "p11-kit-1")
cmd.Stdout = &out
if err := cmd.Run(); err != nil {
return ""
}

path := strings.TrimSpace(out.String())
if _, err := os.Stat(path); err != nil {
if runtime.GOOS != "darwin" {
return ""
}

// pkg-config might return an .so file instead of a .dylib on macOs.
path = strings.Replace(path, ".so", ".dylib", 1)
if _, err := os.Stat(path); err != nil {
return ""
}
}

return path
}

var _ apiv1.CertificateManager = (*PKCS11)(nil)
59 changes: 56 additions & 3 deletions kms/pkcs11/pkcs11_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,22 +25,40 @@ import (
)

func TestNew(t *testing.T) {
tmp := p11Configure
tmp0 := p11Configure
tmp1 := findP11KitProxy
t.Cleanup(func() {
p11Configure = tmp
p11Configure = tmp0
findP11KitProxy = tmp1
})

k := mustPKCS11(t)
t.Cleanup(func() {
k.Close()
})

p11Configure = func(config *crypto11.Config) (P11, error) {
if strings.Contains(config.Path, "fail") {
return nil, errors.New("an error")
}
return k.p11, nil
}

findP11KitProxy = func(ctx context.Context) string {
select {
case <-ctx.Done():
return ""
default:
if fail, _ := ctx.Value("fail").(bool); fail {
return ""
}
return "/usr/local/lib/p11-kit-proxy.so"
}
}

canceledContext, cancel := context.WithCancel(context.Background())
cancel()

type args struct {
ctx context.Context
opts apiv1.Options
Expand Down Expand Up @@ -68,11 +86,20 @@ func TestNew(t *testing.T) {
URI: "pkcs11:module-path=/usr/local/lib/softhsm/libsofthsm2.so;token=pkcs11-test",
Pin: "passowrd",
}}, k, false},
{"fail missing module", args{context.Background(), apiv1.Options{
{"ok with missing module", args{context.Background(), apiv1.Options{
Type: "pkcs11",
URI: "pkcs11:token=pkcs11-test",
Pin: "passowrd",
}}, k, false},
{"fail with missing module", args{context.WithValue(context.Background(), "fail", true), apiv1.Options{
Type: "pkcs11",
URI: "pkcs11:token=pkcs11-test",
Pin: "passowrd",
}}, nil, true},
{"fail findP11KitProxy", args{canceledContext, apiv1.Options{
Type: "pkcs11",
URI: "pkcs11:token=pkcs11-test?pin-value=password",
}}, nil, true},
{"fail missing pin", args{context.Background(), apiv1.Options{
Type: "pkcs11",
URI: "pkcs11:module-path=/usr/local/lib/softhsm/libsofthsm2.so;token=pkcs11-test",
Expand Down Expand Up @@ -834,3 +861,29 @@ func TestPKCS11_Close(t *testing.T) {
})
}
}

func Test_findP11KitProxy(t *testing.T) {
expected := findP11KitProxy(context.Background())

canceledContext, cancel := context.WithCancel(context.Background())
cancel()

type args struct {
ctx context.Context
}
tests := []struct {
name string
args args
want string
}{
{"expected", args{context.Background()}, expected},
{"fail", args{canceledContext}, ""},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := findP11KitProxy(tt.args.ctx); got != tt.want {
t.Errorf("findP11KitProxy() = %v, want %v", got, tt.want)
}
})
}
}