diff options
Diffstat (limited to 'src/home/homectl-pkcs11.c')
| -rw-r--r-- | src/home/homectl-pkcs11.c | 477 |
1 files changed, 477 insertions, 0 deletions
diff --git a/src/home/homectl-pkcs11.c b/src/home/homectl-pkcs11.c new file mode 100644 index 0000000..4b7f833 --- /dev/null +++ b/src/home/homectl-pkcs11.c @@ -0,0 +1,477 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "errno-util.h" +#include "format-table.h" +#include "hexdecoct.h" +#include "homectl-pkcs11.h" +#include "libcrypt-util.h" +#include "memory-util.h" +#include "openssl-util.h" +#include "pkcs11-util.h" +#include "random-util.h" +#include "strv.h" + +struct pkcs11_callback_data { + char *pin_used; + X509 *cert; +}; + +#if HAVE_P11KIT +static void pkcs11_callback_data_release(struct pkcs11_callback_data *data) { + erase_and_free(data->pin_used); + X509_free(data->cert); +} + +static int pkcs11_callback( + CK_FUNCTION_LIST *m, + CK_SESSION_HANDLE session, + CK_SLOT_ID slot_id, + const CK_SLOT_INFO *slot_info, + const CK_TOKEN_INFO *token_info, + P11KitUri *uri, + void *userdata) { + + _cleanup_(erase_and_freep) char *pin_used = NULL; + struct pkcs11_callback_data *data = userdata; + CK_OBJECT_HANDLE object; + int r; + + assert(m); + assert(slot_info); + assert(token_info); + assert(uri); + assert(data); + + /* Called for every token matching our URI */ + + r = pkcs11_token_login(m, session, slot_id, token_info, "home directory operation", "user-home", "pkcs11-pin", UINT64_MAX, &pin_used); + if (r < 0) + return r; + + r = pkcs11_token_find_x509_certificate(m, session, uri, &object); + if (r < 0) + return r; + + r = pkcs11_token_read_x509_certificate(m, session, object, &data->cert); + if (r < 0) + return r; + + /* Let's read some random data off the token and write it to the kernel pool before we generate our + * random key from it. This way we can claim the quality of the RNG is at least as good as the + * kernel's and the token's pool */ + (void) pkcs11_token_acquire_rng(m, session); + + data->pin_used = TAKE_PTR(pin_used); + return 1; +} +#endif + +static int acquire_pkcs11_certificate( + const char *uri, + X509 **ret_cert, + char **ret_pin_used) { + +#if HAVE_P11KIT + _cleanup_(pkcs11_callback_data_release) struct pkcs11_callback_data data = {}; + int r; + + r = pkcs11_find_token(uri, pkcs11_callback, &data); + if (r == -EAGAIN) /* pkcs11_find_token() doesn't log about this error, but all others */ + return log_error_errno(SYNTHETIC_ERRNO(ENXIO), + "Specified PKCS#11 token with URI '%s' not found.", + uri); + if (r < 0) + return r; + + *ret_cert = TAKE_PTR(data.cert); + *ret_pin_used = TAKE_PTR(data.pin_used); + + return 0; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "PKCS#11 tokens not supported on this build."); +#endif +} + +static int encrypt_bytes( + EVP_PKEY *pkey, + const void *decrypted_key, + size_t decrypted_key_size, + void **ret_encrypt_key, + size_t *ret_encrypt_key_size) { + + _cleanup_(EVP_PKEY_CTX_freep) EVP_PKEY_CTX *ctx = NULL; + _cleanup_free_ void *b = NULL; + size_t l; + + ctx = EVP_PKEY_CTX_new(pkey, NULL); + if (!ctx) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to allocate public key context"); + + if (EVP_PKEY_encrypt_init(ctx) <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to initialize public key context"); + + if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to configure PKCS#1 padding"); + + if (EVP_PKEY_encrypt(ctx, NULL, &l, decrypted_key, decrypted_key_size) <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to determine encrypted key size"); + + b = malloc(l); + if (!b) + return log_oom(); + + if (EVP_PKEY_encrypt(ctx, b, &l, decrypted_key, decrypted_key_size) <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to determine encrypted key size"); + + *ret_encrypt_key = TAKE_PTR(b); + *ret_encrypt_key_size = l; + + return 0; +} + +static int add_pkcs11_encrypted_key( + JsonVariant **v, + const char *uri, + const void *encrypted_key, size_t encrypted_key_size, + const void *decrypted_key, size_t decrypted_key_size) { + + _cleanup_(json_variant_unrefp) JsonVariant *l = NULL, *w = NULL, *e = NULL; + _cleanup_(erase_and_freep) char *base64_encoded = NULL, *hashed = NULL; + int r; + + assert(v); + assert(uri); + assert(encrypted_key); + assert(encrypted_key_size > 0); + assert(decrypted_key); + assert(decrypted_key_size > 0); + + /* Before using UNIX hashing on the supplied key we base64 encode it, since crypt_r() and friends + * expect a NUL terminated string, and we use a binary key */ + r = base64mem(decrypted_key, decrypted_key_size, &base64_encoded); + if (r < 0) + return log_error_errno(r, "Failed to base64 encode secret key: %m"); + + r = hash_password(base64_encoded, &hashed); + if (r < 0) + return log_error_errno(errno_or_else(EINVAL), "Failed to UNIX hash secret key: %m"); + + r = json_build(&e, JSON_BUILD_OBJECT( + JSON_BUILD_PAIR("uri", JSON_BUILD_STRING(uri)), + JSON_BUILD_PAIR("data", JSON_BUILD_BASE64(encrypted_key, encrypted_key_size)), + JSON_BUILD_PAIR("hashedPassword", JSON_BUILD_STRING(hashed)))); + if (r < 0) + return log_error_errno(r, "Failed to build encrypted JSON key object: %m"); + + w = json_variant_ref(json_variant_by_key(*v, "privileged")); + l = json_variant_ref(json_variant_by_key(w, "pkcs11EncryptedKey")); + + r = json_variant_append_array(&l, e); + if (r < 0) + return log_error_errno(r, "Failed append PKCS#11 encrypted key: %m"); + + r = json_variant_set_field(&w, "pkcs11EncryptedKey", l); + if (r < 0) + return log_error_errno(r, "Failed to set PKCS#11 encrypted key: %m"); + + r = json_variant_set_field(v, "privileged", w); + if (r < 0) + return log_error_errno(r, "Failed to update privileged field: %m"); + + return 0; +} + +static int add_pkcs11_token_uri(JsonVariant **v, const char *uri) { + _cleanup_(json_variant_unrefp) JsonVariant *w = NULL; + _cleanup_strv_free_ char **l = NULL; + int r; + + assert(v); + assert(uri); + + w = json_variant_ref(json_variant_by_key(*v, "pkcs11TokenUri")); + if (w) { + r = json_variant_strv(w, &l); + if (r < 0) + return log_error_errno(r, "Failed to parse PKCS#11 token list: %m"); + + if (strv_contains(l, uri)) + return 0; + } + + r = strv_extend(&l, uri); + if (r < 0) + return log_oom(); + + w = json_variant_unref(w); + r = json_variant_new_array_strv(&w, l); + if (r < 0) + return log_error_errno(r, "Failed to create PKCS#11 token URI JSON: %m"); + + r = json_variant_set_field(v, "pkcs11TokenUri", w); + if (r < 0) + return log_error_errno(r, "Failed to update PKCS#11 token URI list: %m"); + + return 0; +} + +int identity_add_token_pin(JsonVariant **v, const char *pin) { + _cleanup_(json_variant_unrefp) JsonVariant *w = NULL, *l = NULL; + _cleanup_(strv_free_erasep) char **pins = NULL; + int r; + + assert(v); + + if (isempty(pin)) + return 0; + + w = json_variant_ref(json_variant_by_key(*v, "secret")); + l = json_variant_ref(json_variant_by_key(w, "tokenPin")); + + r = json_variant_strv(l, &pins); + if (r < 0) + return log_error_errno(r, "Failed to convert PIN array: %m"); + + if (strv_find(pins, pin)) + return 0; + + r = strv_extend(&pins, pin); + if (r < 0) + return log_oom(); + + strv_uniq(pins); + + l = json_variant_unref(l); + + r = json_variant_new_array_strv(&l, pins); + if (r < 0) + return log_error_errno(r, "Failed to allocate new PIN array JSON: %m"); + + json_variant_sensitive(l); + + r = json_variant_set_field(&w, "tokenPin", l); + if (r < 0) + return log_error_errno(r, "Failed to update PIN field: %m"); + + r = json_variant_set_field(v, "secret", w); + if (r < 0) + return log_error_errno(r, "Failed to update secret object: %m"); + + return 1; +} + +int identity_add_pkcs11_key_data(JsonVariant **v, const char *uri) { + _cleanup_(erase_and_freep) void *decrypted_key = NULL, *encrypted_key = NULL; + _cleanup_(erase_and_freep) char *pin = NULL; + size_t decrypted_key_size, encrypted_key_size; + _cleanup_(X509_freep) X509 *cert = NULL; + EVP_PKEY *pkey; + RSA *rsa; + int bits; + int r; + + assert(v); + + r = acquire_pkcs11_certificate(uri, &cert, &pin); + if (r < 0) + return r; + + pkey = X509_get0_pubkey(cert); + if (!pkey) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to extract public key from X.509 certificate."); + + if (EVP_PKEY_base_id(pkey) != EVP_PKEY_RSA) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), "X.509 certificate does not refer to RSA key."); + + rsa = EVP_PKEY_get0_RSA(pkey); + if (!rsa) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to acquire RSA public key from X.509 certificate."); + + bits = RSA_bits(rsa); + log_debug("Bits in RSA key: %i", bits); + + /* We use PKCS#1 padding for the RSA cleartext, hence let's leave some extra space for it, hence only + * generate a random key half the size of the RSA length */ + decrypted_key_size = bits / 8 / 2; + + if (decrypted_key_size < 1) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Uh, RSA key size too short?"); + + log_debug("Generating %zu bytes random key.", decrypted_key_size); + + decrypted_key = malloc(decrypted_key_size); + if (!decrypted_key) + return log_oom(); + + r = genuine_random_bytes(decrypted_key, decrypted_key_size, RANDOM_BLOCK); + if (r < 0) + return log_error_errno(r, "Failed to generate random key: %m"); + + r = encrypt_bytes(pkey, decrypted_key, decrypted_key_size, &encrypted_key, &encrypted_key_size); + if (r < 0) + return log_error_errno(r, "Failed to encrypt key: %m"); + + /* Add the token URI to the public part of the record. */ + r = add_pkcs11_token_uri(v, uri); + if (r < 0) + return r; + + /* Include the encrypted version of the random key we just generated in the privileged part of the record */ + r = add_pkcs11_encrypted_key( + v, + uri, + encrypted_key, encrypted_key_size, + decrypted_key, decrypted_key_size); + if (r < 0) + return r; + + /* If we acquired the PIN also include it in the secret section of the record, so that systemd-homed + * can use it if it needs to, given that it likely needs to decrypt the key again to pass to LUKS or + * fscrypt. */ + r = identity_add_token_pin(v, pin); + if (r < 0) + return r; + + return 0; +} + +#if HAVE_P11KIT +static int list_callback( + CK_FUNCTION_LIST *m, + CK_SESSION_HANDLE session, + CK_SLOT_ID slot_id, + const CK_SLOT_INFO *slot_info, + const CK_TOKEN_INFO *token_info, + P11KitUri *uri, + void *userdata) { + + _cleanup_free_ char *token_uri_string = NULL, *token_label = NULL, *token_manufacturer_id = NULL, *token_model = NULL; + _cleanup_(p11_kit_uri_freep) P11KitUri *token_uri = NULL; + Table *t = userdata; + int uri_result, r; + + assert(slot_info); + assert(token_info); + + /* We only care about hardware devices here with a token inserted. Let's filter everything else + * out. (Note that the user can explicitly specify non-hardware tokens if they like, but during + * enumeration we'll filter those, since software tokens are typically the system certificate store + * and such, and it's typically not what people want to bind their home directories to.) */ + if (!FLAGS_SET(token_info->flags, CKF_HW_SLOT|CKF_TOKEN_PRESENT)) + return -EAGAIN; + + token_label = pkcs11_token_label(token_info); + if (!token_label) + return log_oom(); + + token_manufacturer_id = pkcs11_token_manufacturer_id(token_info); + if (!token_manufacturer_id) + return log_oom(); + + token_model = pkcs11_token_model(token_info); + if (!token_model) + return log_oom(); + + token_uri = uri_from_token_info(token_info); + if (!token_uri) + return log_oom(); + + uri_result = p11_kit_uri_format(token_uri, P11_KIT_URI_FOR_ANY, &token_uri_string); + if (uri_result != P11_KIT_URI_OK) + return log_warning_errno(SYNTHETIC_ERRNO(EAGAIN), "Failed to format slot URI: %s", p11_kit_uri_message(uri_result)); + + r = table_add_many( + t, + TABLE_STRING, token_uri_string, + TABLE_STRING, token_label, + TABLE_STRING, token_manufacturer_id, + TABLE_STRING, token_model); + if (r < 0) + return table_log_add_error(r); + + return -EAGAIN; /* keep scanning */ +} +#endif + +int list_pkcs11_tokens(void) { +#if HAVE_P11KIT + _cleanup_(table_unrefp) Table *t = NULL; + int r; + + t = table_new("uri", "label", "manufacturer", "model"); + if (!t) + return log_oom(); + + r = pkcs11_find_token(NULL, list_callback, t); + if (r < 0 && r != -EAGAIN) + return r; + + if (table_get_rows(t) <= 1) { + log_info("No suitable PKCS#11 tokens found."); + return 0; + } + + r = table_print(t, stdout); + if (r < 0) + return log_error_errno(r, "Failed to show device table: %m"); + + return 0; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "PKCS#11 tokens not supported on this build."); +#endif +} + +#if HAVE_P11KIT +static int auto_callback( + CK_FUNCTION_LIST *m, + CK_SESSION_HANDLE session, + CK_SLOT_ID slot_id, + const CK_SLOT_INFO *slot_info, + const CK_TOKEN_INFO *token_info, + P11KitUri *uri, + void *userdata) { + + _cleanup_(p11_kit_uri_freep) P11KitUri *token_uri = NULL; + char **t = userdata; + int uri_result; + + assert(slot_info); + assert(token_info); + + if (!FLAGS_SET(token_info->flags, CKF_HW_SLOT|CKF_TOKEN_PRESENT)) + return -EAGAIN; + + if (*t) + return log_error_errno(SYNTHETIC_ERRNO(ENOTUNIQ), + "More than one suitable PKCS#11 token found."); + + token_uri = uri_from_token_info(token_info); + if (!token_uri) + return log_oom(); + + uri_result = p11_kit_uri_format(token_uri, P11_KIT_URI_FOR_ANY, t); + if (uri_result != P11_KIT_URI_OK) + return log_warning_errno(SYNTHETIC_ERRNO(EAGAIN), "Failed to format slot URI: %s", p11_kit_uri_message(uri_result)); + + return 0; +} +#endif + +int find_pkcs11_token_auto(char **ret) { +#if HAVE_P11KIT + int r; + + r = pkcs11_find_token(NULL, auto_callback, ret); + if (r == -EAGAIN) + return log_error_errno(SYNTHETIC_ERRNO(ENODEV), "No suitable PKCS#11 tokens found."); + if (r < 0) + return r; + + return 0; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "PKCS#11 tokens not supported on this build."); +#endif +} |