cryptenroll: change class in provided PKCS#11 URI if necessary

cryptenroll accepts only PKCS#11 URIs that match both a certificate and a private key in a token.
This patch allows users to provide a PKCS#11 URI that points to a certificate only, and makes possible to use output of some PKCS#11 tools directly.
Internally the patch changes 'type=cert' in the provided PKCS#11 URI to 'type=private' before storing in a LUKS2 header.

Fixes: #23479

1 files changed, 38 insertions, 8 deletions

diff --git a/src/cryptenroll/cryptenroll-pkcs11.c b/src/cryptenroll/cryptenroll-pkcs11.c
index 7d6112e402..ea969102cb 100644
--- a/src/cryptenroll/cryptenroll-pkcs11.c
+++ b/src/cryptenroll/cryptenroll-pkcs11.c
@@ -7,6 +7,30 @@
 #include "openssl-util.h"
 #include "pkcs11-util.h"
 
+static int uri_set_private_class(const char *uri, char **ret_uri) {
+        _cleanup_(sym_p11_kit_uri_freep) P11KitUri *p11kit_uri = NULL;
+        _cleanup_free_ char *private_uri = NULL;
+        int r;
+
+        r = uri_from_string(uri, &p11kit_uri);
+        if (r < 0)
+                return log_error_errno(r, "Failed to parse PKCS#11 URI '%s': %m", uri);
+
+        if (sym_p11_kit_uri_get_attribute(p11kit_uri, CKA_CLASS)) {
+                CK_OBJECT_CLASS class = CKO_PRIVATE_KEY;
+                CK_ATTRIBUTE attribute = { CKA_CLASS, &class, sizeof(class) };
+
+                if (sym_p11_kit_uri_set_attribute(p11kit_uri, &attribute) != P11_KIT_URI_OK)
+                        return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to set class for URI '%s': %m", uri);
+
+                if (sym_p11_kit_uri_format(p11kit_uri, P11_KIT_URI_FOR_ANY, &private_uri) != P11_KIT_URI_OK)
+                        return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to format PKCS#11 URI: %m");
+        }
+
+        *ret_uri = TAKE_PTR(private_uri);
+        return 0;
+}
+
 int enroll_pkcs11(
                 struct crypt_device *cd,
                 const void *volume_key,
@@ -16,13 +40,13 @@ int enroll_pkcs11(
         _cleanup_(erase_and_freep) void *decrypted_key = NULL;
         _cleanup_(erase_and_freep) char *base64_encoded = NULL;
         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
-        _cleanup_free_ char *keyslot_as_string = NULL;
+        _cleanup_free_ char *keyslot_as_string = NULL, *private_uri = NULL;
         size_t decrypted_key_size, saved_key_size;
         _cleanup_free_ void *saved_key = NULL;
         _cleanup_(X509_freep) X509 *cert = NULL;
         ssize_t base64_encoded_size;
         const char *node;
-        int keyslot, r;
+        int r;
 
         assert_se(cd);
         assert_se(volume_key);
@@ -49,7 +73,7 @@ int enroll_pkcs11(
         if (r < 0)
                 return log_error_errno(r, "Failed to set minimal PBKDF: %m");
 
-        keyslot = crypt_keyslot_add_by_volume_key(
+        int keyslot = crypt_keyslot_add_by_volume_key(
                         cd,
                         CRYPT_ANY_SLOT,
                         volume_key,
@@ -62,12 +86,18 @@ int enroll_pkcs11(
         if (asprintf(&keyslot_as_string, "%i", keyslot) < 0)
                 return log_oom();
 
+        /* Change 'type=cert' in the provided URI to 'type=private' before storing in a LUKS2 header.
+           This allows users to use output of some PKCS#11 tools directly without modifications. */
+        r = uri_set_private_class(uri, &private_uri);
+        if (r < 0)
+                return r;
+
         r = json_build(&v,
-                       JSON_BUILD_OBJECT(
-                                       JSON_BUILD_PAIR("type", JSON_BUILD_CONST_STRING("systemd-pkcs11")),
-                                       JSON_BUILD_PAIR("keyslots", JSON_BUILD_ARRAY(JSON_BUILD_STRING(keyslot_as_string))),
-                                       JSON_BUILD_PAIR("pkcs11-uri", JSON_BUILD_STRING(uri)),
-                                       JSON_BUILD_PAIR("pkcs11-key", JSON_BUILD_BASE64(saved_key, saved_key_size))));
+                JSON_BUILD_OBJECT(
+                        JSON_BUILD_PAIR("type", JSON_BUILD_CONST_STRING("systemd-pkcs11")),
+                        JSON_BUILD_PAIR("keyslots", JSON_BUILD_ARRAY(JSON_BUILD_STRING(keyslot_as_string))),
+                        JSON_BUILD_PAIR("pkcs11-uri", JSON_BUILD_STRING(private_uri ?: uri)),
+                        JSON_BUILD_PAIR("pkcs11-key", JSON_BUILD_BASE64(saved_key, saved_key_size))));
         if (r < 0)
                 return log_error_errno(r, "Failed to prepare PKCS#11 JSON token object: %m");