Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 276 insertions, 0 deletions

diff --git a/src/shared/cryptsetup-fido2.c b/src/shared/cryptsetup-fido2.c
new file mode 100644
index 0000000..285b82a
--- /dev/null
+++ b/src/shared/cryptsetup-fido2.c
@@ -0,0 +1,276 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "ask-password-api.h"
+#include "cryptsetup-fido2.h"
+#include "env-util.h"
+#include "fileio.h"
+#include "hexdecoct.h"
+#include "json.h"
+#include "libfido2-util.h"
+#include "parse-util.h"
+#include "random-util.h"
+#include "strv.h"
+
+int acquire_fido2_key(
+                const char *volume_name,
+                const char *friendly_name,
+                const char *device,
+                const char *rp_id,
+                const void *cid,
+                size_t cid_size,
+                const char *key_file,
+                size_t key_file_size,
+                uint64_t key_file_offset,
+                const void *key_data,
+                size_t key_data_size,
+                usec_t until,
+                bool headless,
+                Fido2EnrollFlags required,
+                void **ret_decrypted_key,
+                size_t *ret_decrypted_key_size,
+                AskPasswordFlags ask_password_flags) {
+
+        _cleanup_(erase_and_freep) char *envpw = NULL;
+        _cleanup_strv_free_erase_ char **pins = NULL;
+        _cleanup_free_ void *loaded_salt = NULL;
+        bool device_exists = false;
+        const char *salt;
+        size_t salt_size;
+        int r;
+
+        if ((required & (FIDO2ENROLL_PIN | FIDO2ENROLL_UP | FIDO2ENROLL_UV)) && headless)
+                return log_error_errno(SYNTHETIC_ERRNO(ENOPKG),
+                                        "Local verification is required to unlock this volume, but the 'headless' parameter was set.");
+
+        ask_password_flags |= ASK_PASSWORD_PUSH_CACHE | ASK_PASSWORD_ACCEPT_CACHED;
+
+        assert(cid);
+        assert(key_file || key_data);
+
+        if (key_data) {
+                salt = key_data;
+                salt_size = key_data_size;
+        } else {
+                _cleanup_free_ char *bindname = NULL;
+
+                /* If we read the salt via AF_UNIX, make this client recognizable */
+                if (asprintf(&bindname, "@%" PRIx64"/cryptsetup-fido2/%s", random_u64(), volume_name) < 0)
+                        return log_oom();
+
+                r = read_full_file_full(
+                                AT_FDCWD, key_file,
+                                key_file_offset == 0 ? UINT64_MAX : key_file_offset,
+                                key_file_size == 0 ? SIZE_MAX : key_file_size,
+                                READ_FULL_FILE_CONNECT_SOCKET,
+                                bindname,
+                                (char**) &loaded_salt, &salt_size);
+                if (r < 0)
+                        return r;
+
+                salt = loaded_salt;
+        }
+
+        r = getenv_steal_erase("PIN", &envpw);
+        if (r < 0)
+                return log_error_errno(r, "Failed to acquire password from environment: %m");
+        if (r > 0) {
+                pins = strv_new(envpw);
+                if (!pins)
+                        return log_oom();
+        }
+
+        for (;;) {
+                if (!device_exists) {
+                        /* Before we inquire for the PIN we'll need, if we never talked to the device, check
+                         * if the device actually is plugged in. Otherwise we'll ask for the PIN already when
+                         * the device is not plugged in, which is confusing. */
+
+                        r = fido2_have_device(device);
+                        if (r < 0)
+                                return r;
+                        if (r == 0) /* no device found, return EAGAIN so that caller will wait/watch udev */
+                                return -EAGAIN;
+
+                        device_exists = true;  /* now we know for sure, a device exists, no need to ask again */
+                }
+
+                /* Always make an attempt before asking for PIN.
+                 * fido2_use_hmac_hash() will perform a pre-flight check for whether the credential for
+                 * can be found on one of the connected devices. This way, we can avoid prompting the user
+                 * for a PIN when we are sure that no device can be used. */
+                r = fido2_use_hmac_hash(
+                                device,
+                                rp_id ?: "io.systemd.cryptsetup",
+                                salt, salt_size,
+                                cid, cid_size,
+                                pins,
+                                required,
+                                ret_decrypted_key,
+                                ret_decrypted_key_size);
+                if (!IN_SET(r,
+                            -ENOANO,   /* needs pin */
+                            -ENOLCK))  /* pin incorrect */
+                        return r;
+
+                device_exists = true; /* that a PIN is needed/wasn't correct means that we managed to
+                                       * talk to a device */
+
+                if (headless)
+                        return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "PIN querying disabled via 'headless' option. Use the '$PIN' environment variable.");
+
+                pins = strv_free_erase(pins);
+                r = ask_password_auto("Please enter security token PIN:", "drive-harddisk", NULL, "fido2-pin", "cryptsetup.fido2-pin", until, ask_password_flags, &pins);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to ask for user password: %m");
+
+                ask_password_flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
+        }
+}
+
+int acquire_fido2_key_auto(
+                struct crypt_device *cd,
+                const char *name,
+                const char *friendly_name,
+                const char *fido2_device,
+                usec_t until,
+                bool headless,
+                void **ret_decrypted_key,
+                size_t *ret_decrypted_key_size,
+                AskPasswordFlags ask_password_flags) {
+
+        _cleanup_free_ void *cid = NULL;
+        size_t cid_size = 0;
+        int r, ret = -ENOENT;
+        Fido2EnrollFlags required = 0;
+
+        assert(cd);
+        assert(name);
+        assert(ret_decrypted_key);
+        assert(ret_decrypted_key_size);
+
+        /* Loads FIDO2 metadata from LUKS2 JSON token headers. */
+
+        for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) {
+                _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+                JsonVariant *w;
+                _cleanup_free_ void *salt = NULL;
+                _cleanup_free_ char *rp = NULL;
+                size_t salt_size = 0;
+                int ks;
+
+                r = cryptsetup_get_token_as_json(cd, token, "systemd-fido2", &v);
+                if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
+                        continue;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to read JSON token data off disk: %m");
+
+                ks = cryptsetup_get_keyslot_from_token(v);
+                if (ks < 0) {
+                        /* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by
+                         * us, but by the LUKS2 spec */
+                        log_warning_errno(ks, "Failed to extract keyslot index from FIDO2 JSON data token %i, skipping: %m", token);
+                        continue;
+                }
+
+                w = json_variant_by_key(v, "fido2-credential");
+                if (!w || !json_variant_is_string(w))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "FIDO2 token data lacks 'fido2-credential' field.");
+
+                r = unbase64mem(json_variant_string(w), SIZE_MAX, &cid, &cid_size);
+                if (r < 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Invalid base64 data in 'fido2-credential' field.");
+
+                w = json_variant_by_key(v, "fido2-salt");
+                if (!w || !json_variant_is_string(w))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "FIDO2 token data lacks 'fido2-salt' field.");
+
+                assert(!salt);
+                assert(salt_size == 0);
+                r = unbase64mem(json_variant_string(w), SIZE_MAX, &salt, &salt_size);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to decode base64 encoded salt.");
+
+                w = json_variant_by_key(v, "fido2-rp");
+                if (w) {
+                        /* The "rp" field is optional. */
+
+                        if (!json_variant_is_string(w))
+                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "FIDO2 token data's 'fido2-rp' field is not a string.");
+
+                        assert(!rp);
+                        rp = strdup(json_variant_string(w));
+                        if (!rp)
+                                return log_oom();
+                }
+
+                w = json_variant_by_key(v, "fido2-clientPin-required");
+                if (w) {
+                        /* The "fido2-clientPin-required" field is optional. */
+
+                        if (!json_variant_is_boolean(w))
+                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "FIDO2 token data's 'fido2-clientPin-required' field is not a boolean.");
+
+                        SET_FLAG(required, FIDO2ENROLL_PIN, json_variant_boolean(w));
+                } else
+                        required |= FIDO2ENROLL_PIN_IF_NEEDED; /* compat with 248, where the field was unset */
+
+                w = json_variant_by_key(v, "fido2-up-required");
+                if (w) {
+                        /* The "fido2-up-required" field is optional. */
+
+                        if (!json_variant_is_boolean(w))
+                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "FIDO2 token data's 'fido2-up-required' field is not a boolean.");
+
+                        SET_FLAG(required, FIDO2ENROLL_UP, json_variant_boolean(w));
+                } else
+                        required |= FIDO2ENROLL_UP_IF_NEEDED; /* compat with 248 */
+
+                w = json_variant_by_key(v, "fido2-uv-required");
+                if (w) {
+                        /* The "fido2-uv-required" field is optional. */
+
+                        if (!json_variant_is_boolean(w))
+                                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "FIDO2 token data's 'fido2-uv-required' field is not a boolean.");
+
+                        SET_FLAG(required, FIDO2ENROLL_UV, json_variant_boolean(w));
+                } else
+                        required |= FIDO2ENROLL_UV_OMIT; /* compat with 248 */
+
+                ret = acquire_fido2_key(
+                                name,
+                                friendly_name,
+                                fido2_device,
+                                rp,
+                                cid, cid_size,
+                                /* key_file= */ NULL, /* salt is read from LUKS header instead of key_file */
+                                /* key_file_size= */ 0,
+                                /* key_file_offset= */ 0,
+                                salt, salt_size,
+                                until,
+                                headless,
+                                required,
+                                ret_decrypted_key, ret_decrypted_key_size,
+                                ask_password_flags);
+                if (ret == 0)
+                        break;
+        }
+
+        if (!cid)
+                return log_error_errno(SYNTHETIC_ERRNO(ENXIO),
+                                       "No valid FIDO2 token data found.");
+
+        if (ret == -EAGAIN) /* fido2 device does not exist, or UV is blocked; caller will prompt for retry */
+                return log_debug_errno(ret, "FIDO2 token does not exist, or UV is blocked.");
+        if (ret < 0)
+                return log_error_errno(ret, "Failed to unlock LUKS volume with FIDO2 token: %m");
+
+        log_info("Unlocked volume via automatically discovered security FIDO2 token.");
+        return ret;
+}