src/home/homectl-pkcs11.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "errno-util.h"
   4 #include "format-table.h"
   5 #include "hexdecoct.h"
   6 #include "homectl-pkcs11.h"
   7 #include "libcrypt-util.h"
   8 #include "memory-util.h"
   9 #include "openssl-util.h"
  10 #include "pkcs11-util.h"
  11 #include "random-util.h"
  12 #include "strv.h"
  13
  14 static int add_pkcs11_encrypted_key(
  15                 JsonVariant **v,
  16                 const char *uri,
  17                 const void *encrypted_key, size_t encrypted_key_size,
  18                 const void *decrypted_key, size_t decrypted_key_size) {
  19
  20         _cleanup_(json_variant_unrefp) JsonVariant *l = NULL, *w = NULL, *e = NULL;
  21         _cleanup_(erase_and_freep) char *base64_encoded = NULL, *hashed = NULL;
  22         int r;
  23
  24         assert(v);
  25         assert(uri);
  26         assert(encrypted_key);
  27         assert(encrypted_key_size > 0);
  28         assert(decrypted_key);
  29         assert(decrypted_key_size > 0);
  30
  31         /* Before using UNIX hashing on the supplied key we base64 encode it, since crypt_r() and friends
  32          * expect a NUL terminated string, and we use a binary key */
  33         r = base64mem(decrypted_key, decrypted_key_size, &base64_encoded);
  34         if (r < 0)
  35                 return log_error_errno(r, "Failed to base64 encode secret key: %m");
  36
  37         r = hash_password(base64_encoded, &hashed);
  38         if (r < 0)
  39                 return log_error_errno(errno_or_else(EINVAL), "Failed to UNIX hash secret key: %m");
  40
  41         r = json_build(&e, JSON_BUILD_OBJECT(
  42                                        JSON_BUILD_PAIR("uri", JSON_BUILD_STRING(uri)),
  43                                        JSON_BUILD_PAIR("data", JSON_BUILD_BASE64(encrypted_key, encrypted_key_size)),
  44                                        JSON_BUILD_PAIR("hashedPassword", JSON_BUILD_STRING(hashed))));
  45         if (r < 0)
  46                 return log_error_errno(r, "Failed to build encrypted JSON key object: %m");
  47
  48         w = json_variant_ref(json_variant_by_key(*v, "privileged"));
  49         l = json_variant_ref(json_variant_by_key(w, "pkcs11EncryptedKey"));
  50
  51         r = json_variant_append_array(&l, e);
  52         if (r < 0)
  53                 return log_error_errno(r, "Failed append PKCS#11 encrypted key: %m");
  54
  55         r = json_variant_set_field(&w, "pkcs11EncryptedKey", l);
  56         if (r < 0)
  57                 return log_error_errno(r, "Failed to set PKCS#11 encrypted key: %m");
  58
  59         r = json_variant_set_field(v, "privileged", w);
  60         if (r < 0)
  61                 return log_error_errno(r, "Failed to update privileged field: %m");
  62
  63         return 0;
  64 }
  65
  66 static int add_pkcs11_token_uri(JsonVariant **v, const char *uri) {
  67         _cleanup_(json_variant_unrefp) JsonVariant *w = NULL;
  68         _cleanup_strv_free_ char **l = NULL;
  69         int r;
  70
  71         assert(v);
  72         assert(uri);
  73
  74         w = json_variant_ref(json_variant_by_key(*v, "pkcs11TokenUri"));
  75         if (w) {
  76                 r = json_variant_strv(w, &l);
  77                 if (r < 0)
  78                         return log_error_errno(r, "Failed to parse PKCS#11 token list: %m");
  79
  80                 if (strv_contains(l, uri))
  81                         return 0;
  82         }
  83
  84         r = strv_extend(&l, uri);
  85         if (r < 0)
  86                 return log_oom();
  87
  88         w = json_variant_unref(w);
  89         r = json_variant_new_array_strv(&w, l);
  90         if (r < 0)
  91                 return log_error_errno(r, "Failed to create PKCS#11 token URI JSON: %m");
  92
  93         r = json_variant_set_field(v, "pkcs11TokenUri", w);
  94         if (r < 0)
  95                 return log_error_errno(r, "Failed to update PKCS#11 token URI list: %m");
  96
  97         return 0;
  98 }
  99
 100 int identity_add_token_pin(JsonVariant **v, const char *pin) {
 101         _cleanup_(json_variant_unrefp) JsonVariant *w = NULL, *l = NULL;
 102         _cleanup_(strv_free_erasep) char **pins = NULL;
 103         int r;
 104
 105         assert(v);
 106
 107         if (isempty(pin))
 108                 return 0;
 109
 110         w = json_variant_ref(json_variant_by_key(*v, "secret"));
 111         l = json_variant_ref(json_variant_by_key(w, "tokenPin"));
 112
 113         r = json_variant_strv(l, &pins);
 114         if (r < 0)
 115                 return log_error_errno(r, "Failed to convert PIN array: %m");
 116
 117         if (strv_contains(pins, pin))
 118                 return 0;
 119
 120         r = strv_extend(&pins, pin);
 121         if (r < 0)
 122                 return log_oom();
 123
 124         strv_uniq(pins);
 125
 126         l = json_variant_unref(l);
 127
 128         r = json_variant_new_array_strv(&l, pins);
 129         if (r < 0)
 130                 return log_error_errno(r, "Failed to allocate new PIN array JSON: %m");
 131
 132         json_variant_sensitive(l);
 133
 134         r = json_variant_set_field(&w, "tokenPin", l);
 135         if (r < 0)
 136                 return log_error_errno(r, "Failed to update PIN field: %m");
 137
 138         r = json_variant_set_field(v, "secret", w);
 139         if (r < 0)
 140                 return log_error_errno(r, "Failed to update secret object: %m");
 141
 142         return 1;
 143 }
 144
 145 static int acquire_pkcs11_certificate(
 146                 const char *uri,
 147                 const char *askpw_friendly_name,
 148                 const char *askpw_icon_name,
 149                 X509 **ret_cert,
 150                 char **ret_pin_used) {
 151 #if HAVE_P11KIT
 152         return pkcs11_acquire_certificate(uri, askpw_friendly_name, askpw_icon_name, ret_cert, ret_pin_used);
 153 #else
 154         return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
 155                                "PKCS#11 tokens not supported on this build.");
 156 #endif
 157 }
 158
 159 int identity_add_pkcs11_key_data(JsonVariant **v, const char *uri) {
 160         _cleanup_(erase_and_freep) void *decrypted_key = NULL, *encrypted_key = NULL;
 161         _cleanup_(erase_and_freep) char *pin = NULL;
 162         size_t decrypted_key_size, encrypted_key_size;
 163         _cleanup_(X509_freep) X509 *cert = NULL;
 164         EVP_PKEY *pkey;
 165         int r;
 166
 167         assert(v);
 168
 169         r = acquire_pkcs11_certificate(uri, "home directory operation", "user-home", &cert, &pin);
 170         if (r < 0)
 171                 return r;
 172
 173         pkey = X509_get0_pubkey(cert);
 174         if (!pkey)
 175                 return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to extract public key from X.509 certificate.");
 176
 177         r = rsa_pkey_to_suitable_key_size(pkey, &decrypted_key_size);
 178         if (r < 0)
 179                 return log_error_errno(r, "Failed to extract RSA key size from X509 certificate.");
 180
 181         log_debug("Generating %zu bytes random key.", decrypted_key_size);
 182
 183         decrypted_key = malloc(decrypted_key_size);
 184         if (!decrypted_key)
 185                 return log_oom();
 186
 187         r = crypto_random_bytes(decrypted_key, decrypted_key_size);
 188         if (r < 0)
 189                 return log_error_errno(r, "Failed to generate random key: %m");
 190
 191         r = rsa_encrypt_bytes(pkey, decrypted_key, decrypted_key_size, &encrypted_key, &encrypted_key_size);
 192         if (r < 0)
 193                 return log_error_errno(r, "Failed to encrypt key: %m");
 194
 195         /* Add the token URI to the public part of the record. */
 196         r = add_pkcs11_token_uri(v, uri);
 197         if (r < 0)
 198                 return r;
 199
 200         /* Include the encrypted version of the random key we just generated in the privileged part of the record */
 201         r = add_pkcs11_encrypted_key(
 202                         v,
 203                         uri,
 204                         encrypted_key, encrypted_key_size,
 205                         decrypted_key, decrypted_key_size);
 206         if (r < 0)
 207                 return r;
 208
 209         /* If we acquired the PIN also include it in the secret section of the record, so that systemd-homed
 210          * can use it if it needs to, given that it likely needs to decrypt the key again to pass to LUKS or
 211          * fscrypt. */
 212         r = identity_add_token_pin(v, pin);
 213         if (r < 0)
 214                 return r;
 215
 216         return 0;
 217 }