diff options
Diffstat (limited to 'src/shared/libfido2-util.c')
| -rw-r--r-- | src/shared/libfido2-util.c | 1164 |
1 files changed, 1164 insertions, 0 deletions
diff --git a/src/shared/libfido2-util.c b/src/shared/libfido2-util.c new file mode 100644 index 0000000..525849e --- /dev/null +++ b/src/shared/libfido2-util.c @@ -0,0 +1,1164 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "libfido2-util.h" + +#if HAVE_LIBFIDO2 +#include "alloc-util.h" +#include "ask-password-api.h" +#include "dlfcn-util.h" +#include "format-table.h" +#include "glyph-util.h" +#include "log.h" +#include "memory-util.h" +#include "random-util.h" +#include "strv.h" +#include "unistd.h" + +static void *libfido2_dl = NULL; + +int (*sym_fido_assert_allow_cred)(fido_assert_t *, const unsigned char *, size_t) = NULL; +void (*sym_fido_assert_free)(fido_assert_t **) = NULL; +size_t (*sym_fido_assert_hmac_secret_len)(const fido_assert_t *, size_t) = NULL; +const unsigned char* (*sym_fido_assert_hmac_secret_ptr)(const fido_assert_t *, size_t) = NULL; +fido_assert_t* (*sym_fido_assert_new)(void) = NULL; +int (*sym_fido_assert_set_clientdata_hash)(fido_assert_t *, const unsigned char *, size_t) = NULL; +int (*sym_fido_assert_set_extensions)(fido_assert_t *, int) = NULL; +int (*sym_fido_assert_set_hmac_salt)(fido_assert_t *, const unsigned char *, size_t) = NULL; +int (*sym_fido_assert_set_rp)(fido_assert_t *, const char *) = NULL; +int (*sym_fido_assert_set_up)(fido_assert_t *, fido_opt_t) = NULL; +int (*sym_fido_assert_set_uv)(fido_assert_t *, fido_opt_t) = NULL; +size_t (*sym_fido_cbor_info_extensions_len)(const fido_cbor_info_t *) = NULL; +char **(*sym_fido_cbor_info_extensions_ptr)(const fido_cbor_info_t *) = NULL; +void (*sym_fido_cbor_info_free)(fido_cbor_info_t **) = NULL; +fido_cbor_info_t* (*sym_fido_cbor_info_new)(void) = NULL; +size_t (*sym_fido_cbor_info_options_len)(const fido_cbor_info_t *) = NULL; +char** (*sym_fido_cbor_info_options_name_ptr)(const fido_cbor_info_t *) = NULL; +const bool* (*sym_fido_cbor_info_options_value_ptr)(const fido_cbor_info_t *) = NULL; +void (*sym_fido_cred_free)(fido_cred_t **) = NULL; +size_t (*sym_fido_cred_id_len)(const fido_cred_t *) = NULL; +const unsigned char* (*sym_fido_cred_id_ptr)(const fido_cred_t *) = NULL; +fido_cred_t* (*sym_fido_cred_new)(void) = NULL; +int (*sym_fido_cred_set_clientdata_hash)(fido_cred_t *, const unsigned char *, size_t) = NULL; +int (*sym_fido_cred_set_extensions)(fido_cred_t *, int) = NULL; +int (*sym_fido_cred_set_rk)(fido_cred_t *, fido_opt_t) = NULL; +int (*sym_fido_cred_set_rp)(fido_cred_t *, const char *, const char *) = NULL; +int (*sym_fido_cred_set_type)(fido_cred_t *, int) = NULL; +int (*sym_fido_cred_set_user)(fido_cred_t *, const unsigned char *, size_t, const char *, const char *, const char *) = NULL; +int (*sym_fido_cred_set_uv)(fido_cred_t *, fido_opt_t) = NULL; +void (*sym_fido_dev_free)(fido_dev_t **) = NULL; +int (*sym_fido_dev_get_assert)(fido_dev_t *, fido_assert_t *, const char *) = NULL; +int (*sym_fido_dev_get_cbor_info)(fido_dev_t *, fido_cbor_info_t *) = NULL; +void (*sym_fido_dev_info_free)(fido_dev_info_t **, size_t) = NULL; +int (*sym_fido_dev_info_manifest)(fido_dev_info_t *, size_t, size_t *) = NULL; +const char* (*sym_fido_dev_info_manufacturer_string)(const fido_dev_info_t *) = NULL; +const char* (*sym_fido_dev_info_product_string)(const fido_dev_info_t *) = NULL; +fido_dev_info_t* (*sym_fido_dev_info_new)(size_t) = NULL; +const char* (*sym_fido_dev_info_path)(const fido_dev_info_t *) = NULL; +const fido_dev_info_t* (*sym_fido_dev_info_ptr)(const fido_dev_info_t *, size_t) = NULL; +bool (*sym_fido_dev_is_fido2)(const fido_dev_t *) = NULL; +int (*sym_fido_dev_make_cred)(fido_dev_t *, fido_cred_t *, const char *) = NULL; +fido_dev_t* (*sym_fido_dev_new)(void) = NULL; +int (*sym_fido_dev_open)(fido_dev_t *, const char *) = NULL; +int (*sym_fido_dev_close)(fido_dev_t *) = NULL; +const char* (*sym_fido_strerr)(int) = NULL; + +int dlopen_libfido2(void) { + return dlopen_many_sym_or_warn( + &libfido2_dl, "libfido2.so.1", LOG_DEBUG, + DLSYM_ARG(fido_assert_allow_cred), + DLSYM_ARG(fido_assert_free), + DLSYM_ARG(fido_assert_hmac_secret_len), + DLSYM_ARG(fido_assert_hmac_secret_ptr), + DLSYM_ARG(fido_assert_new), + DLSYM_ARG(fido_assert_set_clientdata_hash), + DLSYM_ARG(fido_assert_set_extensions), + DLSYM_ARG(fido_assert_set_hmac_salt), + DLSYM_ARG(fido_assert_set_rp), + DLSYM_ARG(fido_assert_set_up), + DLSYM_ARG(fido_assert_set_uv), + DLSYM_ARG(fido_cbor_info_extensions_len), + DLSYM_ARG(fido_cbor_info_extensions_ptr), + DLSYM_ARG(fido_cbor_info_free), + DLSYM_ARG(fido_cbor_info_new), + DLSYM_ARG(fido_cbor_info_options_len), + DLSYM_ARG(fido_cbor_info_options_name_ptr), + DLSYM_ARG(fido_cbor_info_options_value_ptr), + DLSYM_ARG(fido_cred_free), + DLSYM_ARG(fido_cred_id_len), + DLSYM_ARG(fido_cred_id_ptr), + DLSYM_ARG(fido_cred_new), + DLSYM_ARG(fido_cred_set_clientdata_hash), + DLSYM_ARG(fido_cred_set_extensions), + DLSYM_ARG(fido_cred_set_rk), + DLSYM_ARG(fido_cred_set_rp), + DLSYM_ARG(fido_cred_set_type), + DLSYM_ARG(fido_cred_set_user), + DLSYM_ARG(fido_cred_set_uv), + DLSYM_ARG(fido_dev_free), + DLSYM_ARG(fido_dev_get_assert), + DLSYM_ARG(fido_dev_get_cbor_info), + DLSYM_ARG(fido_dev_info_free), + DLSYM_ARG(fido_dev_info_manifest), + DLSYM_ARG(fido_dev_info_manufacturer_string), + DLSYM_ARG(fido_dev_info_new), + DLSYM_ARG(fido_dev_info_path), + DLSYM_ARG(fido_dev_info_product_string), + DLSYM_ARG(fido_dev_info_ptr), + DLSYM_ARG(fido_dev_is_fido2), + DLSYM_ARG(fido_dev_make_cred), + DLSYM_ARG(fido_dev_new), + DLSYM_ARG(fido_dev_open), + DLSYM_ARG(fido_dev_close), + DLSYM_ARG(fido_strerr)); +} + +static int verify_features( + fido_dev_t *d, + const char *path, + int log_level, /* the log level to use when device is not FIDO2 with hmac-secret */ + bool *ret_has_rk, + bool *ret_has_client_pin, + bool *ret_has_up, + bool *ret_has_uv) { + + _cleanup_(fido_cbor_info_free_wrapper) fido_cbor_info_t *di = NULL; + bool found_extension = false; + char **e, **o; + const bool *b; + bool has_rk = false, has_client_pin = false, has_up = true, has_uv = false; /* Defaults are per table in 5.4 in FIDO2 spec */ + size_t n; + int r; + + assert(d); + assert(path); + + if (!sym_fido_dev_is_fido2(d)) + return log_full_errno(log_level, SYNTHETIC_ERRNO(ENODEV), + "Specified device %s is not a FIDO2 device.", path); + + di = sym_fido_cbor_info_new(); + if (!di) + return log_oom(); + + r = sym_fido_dev_get_cbor_info(d, di); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to get CBOR device info for %s: %s", path, sym_fido_strerr(r)); + + e = sym_fido_cbor_info_extensions_ptr(di); + n = sym_fido_cbor_info_extensions_len(di); + for (size_t i = 0; i < n; i++) { + log_debug("FIDO2 device implements extension: %s", e[i]); + if (streq(e[i], "hmac-secret")) + found_extension = true; + } + + o = sym_fido_cbor_info_options_name_ptr(di); + b = sym_fido_cbor_info_options_value_ptr(di); + n = sym_fido_cbor_info_options_len(di); + for (size_t i = 0; i < n; i++) { + log_debug("FIDO2 device implements option %s: %s", o[i], yes_no(b[i])); + if (streq(o[i], "rk")) + has_rk = b[i]; + if (streq(o[i], "clientPin")) + has_client_pin = b[i]; + if (streq(o[i], "up")) + has_up = b[i]; + if (streq(o[i], "uv")) + has_uv = b[i]; + } + + if (!found_extension) + return log_full_errno(log_level, + SYNTHETIC_ERRNO(ENODEV), + "Specified device %s is a FIDO2 device, but does not support the required HMAC-SECRET extension.", path); + + log_debug("Has rk ('Resident Key') support: %s\n" + "Has clientPin support: %s\n" + "Has up ('User Presence') support: %s\n" + "Has uv ('User Verification') support: %s\n", + yes_no(has_rk), + yes_no(has_client_pin), + yes_no(has_up), + yes_no(has_uv)); + + if (ret_has_rk) + *ret_has_rk = has_rk; + if (ret_has_client_pin) + *ret_has_client_pin = has_client_pin; + if (ret_has_up) + *ret_has_up = has_up; + if (ret_has_uv) + *ret_has_uv = has_uv; + + return 0; +} + +static int fido2_use_hmac_hash_specific_token( + const char *path, + const char *rp_id, + const void *salt, + size_t salt_size, + const void *cid, + size_t cid_size, + char **pins, + Fido2EnrollFlags required, /* client pin/user presence required */ + void **ret_hmac, + size_t *ret_hmac_size) { + + _cleanup_(fido_assert_free_wrapper) fido_assert_t *a = NULL; + _cleanup_(fido_dev_free_wrapper) fido_dev_t *d = NULL; + _cleanup_(erase_and_freep) void *hmac_copy = NULL; + bool has_up, has_client_pin, has_uv; + size_t hmac_size; + const void *hmac; + int r; + + assert(path); + assert(rp_id); + assert(salt); + assert(cid); + assert(ret_hmac); + assert(ret_hmac_size); + + d = sym_fido_dev_new(); + if (!d) + return log_oom(); + + r = sym_fido_dev_open(d, path); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to open FIDO2 device %s: %s", path, sym_fido_strerr(r)); + + r = verify_features(d, path, LOG_ERR, NULL, &has_client_pin, &has_up, &has_uv); + if (r < 0) + return r; + + if (!has_client_pin && FLAGS_SET(required, FIDO2ENROLL_PIN)) + return log_error_errno(SYNTHETIC_ERRNO(EHWPOISON), + "PIN required to unlock, but FIDO2 device %s does not support it.", + path); + + if (!has_up && FLAGS_SET(required, FIDO2ENROLL_UP)) + return log_error_errno(SYNTHETIC_ERRNO(EHWPOISON), + "User presence test required to unlock, but FIDO2 device %s does not support it.", + path); + + if (!has_uv && FLAGS_SET(required, FIDO2ENROLL_UV)) + return log_error_errno(SYNTHETIC_ERRNO(EHWPOISON), + "User verification required to unlock, but FIDO2 device %s does not support it.", + path); + + a = sym_fido_assert_new(); + if (!a) + return log_oom(); + + r = sym_fido_assert_set_extensions(a, FIDO_EXT_HMAC_SECRET); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to enable HMAC-SECRET extension on FIDO2 assertion: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_hmac_salt(a, salt, salt_size); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set salt on FIDO2 assertion: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_rp(a, rp_id); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 assertion ID: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_clientdata_hash(a, (const unsigned char[32]) {}, 32); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 assertion client data hash: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_allow_cred(a, cid, cid_size); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to add FIDO2 assertion credential ID: %s", sym_fido_strerr(r)); + + log_info("Asking FIDO2 token for authentication."); + + if (has_up) { + r = sym_fido_assert_set_up(a, FLAGS_SET(required, FIDO2ENROLL_UP) ? FIDO_OPT_TRUE : FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to %s FIDO2 user presence test: %s", + enable_disable(FLAGS_SET(required, FIDO2ENROLL_UP)), + sym_fido_strerr(r)); + + if (FLAGS_SET(required, FIDO2ENROLL_UP)) + log_notice("%s%sPlease confirm presence on security token to unlock.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + } + + if (has_uv && !FLAGS_SET(required, FIDO2ENROLL_UV_OMIT)) { + r = sym_fido_assert_set_uv(a, FLAGS_SET(required, FIDO2ENROLL_UV) ? FIDO_OPT_TRUE : FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to %s FIDO2 user verification: %s", + enable_disable(FLAGS_SET(required, FIDO2ENROLL_UV)), + sym_fido_strerr(r)); + + if (FLAGS_SET(required, FIDO2ENROLL_UV)) + log_notice("%s%sPlease verify user on security token to unlock.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + } + + for (;;) { + bool retry_with_up = false, retry_with_pin = false; + + if (FLAGS_SET(required, FIDO2ENROLL_PIN)) { + /* OK, we need a pin, try with all pins in turn */ + if (strv_isempty(pins)) + r = FIDO_ERR_PIN_REQUIRED; + else + STRV_FOREACH(i, pins) { + r = sym_fido_dev_get_assert(d, a, *i); + if (r != FIDO_ERR_PIN_INVALID) + break; + } + + } else + r = sym_fido_dev_get_assert(d, a, NULL); + + /* In some conditions, where a PIN or UP is required we might accept that. Let's check the + * conditions and if so try immediately again. */ + + switch (r) { + + case FIDO_ERR_UP_REQUIRED: + /* So the token asked for "up". Try to turn it on, for compat with systemd 248 and try again. */ + + if (!has_up) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for user presence test but doesn't advertise 'up' feature."); + + if (FLAGS_SET(required, FIDO2ENROLL_UP)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for user presence test but was already enabled."); + + if (FLAGS_SET(required, FIDO2ENROLL_UP_IF_NEEDED)) { + log_notice("%s%sPlease confirm presence on security to unlock.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + retry_with_up = true; + } + + break; + + case FIDO_ERR_UNSUPPORTED_OPTION: + /* AuthenTrend ATKey.Pro returns this instead of FIDO_ERR_UP_REQUIRED, let's handle + * it gracefully (also see below.) */ + + if (has_up && (required & (FIDO2ENROLL_UP|FIDO2ENROLL_UP_IF_NEEDED)) == FIDO2ENROLL_UP_IF_NEEDED) { + log_notice("%s%sGot unsupported option error when when user presence test is turned off. Trying with user presence test turned on.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + retry_with_up = true; + } + + break; + + case FIDO_ERR_PIN_REQUIRED: + /* A pin was requested. Maybe supply one, if we are configured to do so on request */ + + if (!has_client_pin) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for PIN but doesn't advertise 'clientPin' feature."); + + if (FLAGS_SET(required, FIDO2ENROLL_PIN) && !strv_isempty(pins)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for PIN but one was already supplied."); + + if ((required & (FIDO2ENROLL_PIN|FIDO2ENROLL_PIN_IF_NEEDED)) == FIDO2ENROLL_PIN_IF_NEEDED) { + /* If a PIN so far wasn't specified but is requested by the device, and + * FIDO2ENROLL_PIN_IF_NEEDED is set, then provide it */ + log_debug("Retrying to create credential with PIN."); + retry_with_pin = true; + } + + break; + + default: + break; + } + + if (!retry_with_up && !retry_with_pin) + break; + + if (retry_with_up) { + r = sym_fido_assert_set_up(a, FIDO_OPT_TRUE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to enable FIDO2 user presence test: %s", sym_fido_strerr(r)); + + required |= FIDO2ENROLL_UP; + } + + if (retry_with_pin) + required |= FIDO2ENROLL_PIN; + } + + switch (r) { + case FIDO_OK: + break; + case FIDO_ERR_NO_CREDENTIALS: + return log_error_errno(SYNTHETIC_ERRNO(EBADSLT), + "Wrong security token; needed credentials not present on token."); + case FIDO_ERR_PIN_REQUIRED: + return log_error_errno(SYNTHETIC_ERRNO(ENOANO), + "Security token requires PIN."); + case FIDO_ERR_PIN_AUTH_BLOCKED: + return log_error_errno(SYNTHETIC_ERRNO(EOWNERDEAD), + "PIN of security token is blocked, please remove/reinsert token."); +#ifdef FIDO_ERR_UV_BLOCKED + case FIDO_ERR_UV_BLOCKED: + return log_error_errno(SYNTHETIC_ERRNO(EOWNERDEAD), + "Verification of security token is blocked, please remove/reinsert token."); +#endif + case FIDO_ERR_PIN_INVALID: + return log_error_errno(SYNTHETIC_ERRNO(ENOLCK), + "PIN of security token incorrect."); + case FIDO_ERR_UP_REQUIRED: + return log_error_errno(SYNTHETIC_ERRNO(EMEDIUMTYPE), + "User presence required."); + case FIDO_ERR_ACTION_TIMEOUT: + return log_error_errno(SYNTHETIC_ERRNO(ENOSTR), + "Token action timeout. (User didn't interact with token quickly enough.)"); + default: + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to ask token for assertion: %s", sym_fido_strerr(r)); + } + + hmac = sym_fido_assert_hmac_secret_ptr(a, 0); + if (!hmac) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to retrieve HMAC secret."); + + hmac_size = sym_fido_assert_hmac_secret_len(a, 0); + + hmac_copy = memdup(hmac, hmac_size); + if (!hmac_copy) + return log_oom(); + + *ret_hmac = TAKE_PTR(hmac_copy); + *ret_hmac_size = hmac_size; + return 0; +} + +/* COSE_ECDH_ES256 is not usable with fido_cred_set_type() thus it's not listed here. */ +static const char *fido2_algorithm_to_string(int alg) { + switch(alg) { + case COSE_ES256: + return "es256"; + case COSE_RS256: + return "rs256"; + case COSE_EDDSA: + return "eddsa"; + default: + return NULL; + } +} + +int fido2_use_hmac_hash( + const char *device, + const char *rp_id, + const void *salt, + size_t salt_size, + const void *cid, + size_t cid_size, + char **pins, + Fido2EnrollFlags required, /* client pin/user presence required */ + void **ret_hmac, + size_t *ret_hmac_size) { + + size_t allocated = 64, found = 0; + fido_dev_info_t *di = NULL; + int r; + + r = dlopen_libfido2(); + if (r < 0) + return log_error_errno(r, "FIDO2 support is not installed."); + + if (device) + return fido2_use_hmac_hash_specific_token(device, rp_id, salt, salt_size, cid, cid_size, pins, required, ret_hmac, ret_hmac_size); + + di = sym_fido_dev_info_new(allocated); + if (!di) + return log_oom(); + + r = sym_fido_dev_info_manifest(di, allocated, &found); + if (r == FIDO_ERR_INTERNAL) { + /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */ + r = log_debug_errno(SYNTHETIC_ERRNO(EAGAIN), "Got FIDO_ERR_INTERNAL, assuming no devices."); + goto finish; + } + if (r != FIDO_OK) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", sym_fido_strerr(r)); + goto finish; + } + + for (size_t i = 0; i < found; i++) { + const fido_dev_info_t *entry; + const char *path; + + entry = sym_fido_dev_info_ptr(di, i); + if (!entry) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to get device information for FIDO device %zu.", i); + goto finish; + } + + path = sym_fido_dev_info_path(entry); + if (!path) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to query FIDO device path."); + goto finish; + } + + r = fido2_use_hmac_hash_specific_token(path, rp_id, salt, salt_size, cid, cid_size, pins, required, ret_hmac, ret_hmac_size); + if (!IN_SET(r, + -EBADSLT, /* device doesn't understand our credential hash */ + -ENODEV /* device is not a FIDO2 device with HMAC-SECRET */)) + goto finish; + } + + r = -EAGAIN; + +finish: + sym_fido_dev_info_free(&di, allocated); + return r; +} + +#define FIDO2_SALT_SIZE 32 + +int fido2_generate_hmac_hash( + const char *device, + const char *rp_id, + const char *rp_name, + const void *user_id, size_t user_id_len, + const char *user_name, + const char *user_display_name, + const char *user_icon, + const char *askpw_icon_name, + Fido2EnrollFlags lock_with, + int cred_alg, + void **ret_cid, size_t *ret_cid_size, + void **ret_salt, size_t *ret_salt_size, + void **ret_secret, size_t *ret_secret_size, + char **ret_usedpin, + Fido2EnrollFlags *ret_locked_with) { + + _cleanup_(erase_and_freep) void *salt = NULL, *secret_copy = NULL; + _cleanup_(fido_assert_free_wrapper) fido_assert_t *a = NULL; + _cleanup_(fido_cred_free_wrapper) fido_cred_t *c = NULL; + _cleanup_(fido_dev_free_wrapper) fido_dev_t *d = NULL; + _cleanup_(erase_and_freep) char *used_pin = NULL; + bool has_rk, has_client_pin, has_up, has_uv; + _cleanup_free_ char *cid_copy = NULL; + size_t cid_size, secret_size; + const void *cid, *secret; + int r; + + assert(device); + assert(ret_cid); + assert(ret_cid_size); + assert(ret_salt); + assert(ret_salt_size); + assert(ret_secret); + assert(ret_secret_size); + + /* Construction is like this: we generate a salt of 32 bytes. We then ask the FIDO2 device to + * HMAC-SHA256 it for us with its internal key. The result is the key used by LUKS and account + * authentication. LUKS and UNIX password auth all do their own salting before hashing, so that FIDO2 + * device never sees the volume key. + * + * S = HMAC-SHA256(I, D) + * + * with: S → LUKS/account authentication key (never stored) + * I → internal key on FIDO2 device (stored in the FIDO2 device) + * D → salt we generate here (stored in the privileged part of the JSON record) + * + */ + + assert(device); + assert((lock_with & ~(FIDO2ENROLL_PIN|FIDO2ENROLL_UP|FIDO2ENROLL_UV)) == 0); + + r = dlopen_libfido2(); + if (r < 0) + return log_error_errno(r, "FIDO2 token support is not installed."); + + salt = malloc(FIDO2_SALT_SIZE); + if (!salt) + return log_oom(); + + r = crypto_random_bytes(salt, FIDO2_SALT_SIZE); + if (r < 0) + return log_error_errno(r, "Failed to generate salt: %m"); + + d = sym_fido_dev_new(); + if (!d) + return log_oom(); + + r = sym_fido_dev_open(d, device); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to open FIDO2 device %s: %s", device, sym_fido_strerr(r)); + + r = verify_features(d, device, LOG_ERR, &has_rk, &has_client_pin, &has_up, &has_uv); + if (r < 0) + return r; + + /* While enrolling degrade gracefully if the requested feature set isn't available, but let the user know */ + if (!has_client_pin && FLAGS_SET(lock_with, FIDO2ENROLL_PIN)) { + log_notice("Requested to lock with PIN, but FIDO2 device %s does not support it, disabling.", device); + lock_with &= ~FIDO2ENROLL_PIN; + } + + if (!has_up && FLAGS_SET(lock_with, FIDO2ENROLL_UP)) { + log_notice("Locking with user presence test requested, but FIDO2 device %s does not support it, disabling.", device); + lock_with &= ~FIDO2ENROLL_UP; + } + + if (!has_uv && FLAGS_SET(lock_with, FIDO2ENROLL_UV)) { + log_notice("Locking with user verification test requested, but FIDO2 device %s does not support it, disabling.", device); + lock_with &= ~FIDO2ENROLL_UV; + } + + c = sym_fido_cred_new(); + if (!c) + return log_oom(); + + r = sym_fido_cred_set_extensions(c, FIDO_EXT_HMAC_SECRET); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to enable HMAC-SECRET extension on FIDO2 credential: %s", sym_fido_strerr(r)); + + r = sym_fido_cred_set_rp(c, rp_id, rp_name); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 credential relying party ID/name: %s", sym_fido_strerr(r)); + + r = sym_fido_cred_set_type(c, cred_alg); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 credential type to %s: %s", fido2_algorithm_to_string(cred_alg), sym_fido_strerr(r)); + + r = sym_fido_cred_set_user( + c, + user_id, user_id_len, + user_name, + user_display_name, + user_icon); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 credential user data: %s", sym_fido_strerr(r)); + + r = sym_fido_cred_set_clientdata_hash(c, (const unsigned char[32]) {}, 32); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 client data hash: %s", sym_fido_strerr(r)); + + if (has_rk) { + r = sym_fido_cred_set_rk(c, FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to turn off FIDO2 resident key option of credential: %s", sym_fido_strerr(r)); + } + + if (has_uv) { + r = sym_fido_cred_set_uv(c, FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to turn off FIDO2 user verification option of credential: %s", sym_fido_strerr(r)); + } + + /* As per specification "up" is assumed to be implicit when making credentials, hence we don't + * explicitly enable/disable it here */ + + log_info("Initializing FIDO2 credential on security token."); + + if (has_uv || has_up) + log_notice("%s%s(Hint: This might require confirmation of user presence on security token.)", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + + r = sym_fido_dev_make_cred(d, c, NULL); + if (r == FIDO_ERR_PIN_REQUIRED) { + + if (!has_client_pin) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for PIN but doesn't advertise 'clientPin' feature."); + + for (;;) { + _cleanup_(strv_free_erasep) char **pin = NULL; + + r = ask_password_auto("Please enter security token PIN:", askpw_icon_name, NULL, "fido2-pin", "fido2-pin", USEC_INFINITY, 0, &pin); + if (r < 0) + return log_error_errno(r, "Failed to acquire user PIN: %m"); + + r = FIDO_ERR_PIN_INVALID; + STRV_FOREACH(i, pin) { + if (isempty(*i)) { + log_notice("PIN may not be empty."); + continue; + } + + r = sym_fido_dev_make_cred(d, c, *i); + if (r == FIDO_OK) { + used_pin = strdup(*i); + if (!used_pin) + return log_oom(); + break; + } + if (r != FIDO_ERR_PIN_INVALID) + break; + } + + if (r != FIDO_ERR_PIN_INVALID) + break; + + log_notice("PIN incorrect, please try again."); + } + } + if (r == FIDO_ERR_PIN_AUTH_BLOCKED) + return log_notice_errno(SYNTHETIC_ERRNO(EPERM), + "Token PIN is currently blocked, please remove and reinsert token."); +#ifdef FIDO_ERR_UV_BLOCKED + if (r == FIDO_ERR_UV_BLOCKED) + return log_notice_errno(SYNTHETIC_ERRNO(EPERM), + "Token verification is currently blocked, please remove and reinsert token."); +#endif + if (r == FIDO_ERR_ACTION_TIMEOUT) + return log_error_errno(SYNTHETIC_ERRNO(ENOSTR), + "Token action timeout. (User didn't interact with token quickly enough.)"); + if (r == FIDO_ERR_UNSUPPORTED_ALGORITHM) + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "Token doesn't support credential algorithm %s.", fido2_algorithm_to_string(cred_alg)); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to generate FIDO2 credential: %s", sym_fido_strerr(r)); + + cid = sym_fido_cred_id_ptr(c); + if (!cid) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to get FIDO2 credential ID."); + + cid_size = sym_fido_cred_id_len(c); + + a = sym_fido_assert_new(); + if (!a) + return log_oom(); + + r = sym_fido_assert_set_extensions(a, FIDO_EXT_HMAC_SECRET); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to enable HMAC-SECRET extension on FIDO2 assertion: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_hmac_salt(a, salt, FIDO2_SALT_SIZE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set salt on FIDO2 assertion: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_rp(a, rp_id); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 assertion ID: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_set_clientdata_hash(a, (const unsigned char[32]) {}, 32); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to set FIDO2 assertion client data hash: %s", sym_fido_strerr(r)); + + r = sym_fido_assert_allow_cred(a, cid, cid_size); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to add FIDO2 assertion credential ID: %s", sym_fido_strerr(r)); + + log_info("Generating secret key on FIDO2 security token."); + + if (has_up) { + r = sym_fido_assert_set_up(a, FLAGS_SET(lock_with, FIDO2ENROLL_UP) ? FIDO_OPT_TRUE : FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to %s FIDO2 user presence test: %s", + enable_disable(FLAGS_SET(lock_with, FIDO2ENROLL_UP)), + sym_fido_strerr(r)); + + if (FLAGS_SET(lock_with, FIDO2ENROLL_UP)) + log_notice("%s%sIn order to allow secret key generation, please confirm presence on security token.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + } + + if (has_uv) { + r = sym_fido_assert_set_uv(a, FLAGS_SET(lock_with, FIDO2ENROLL_UV) ? FIDO_OPT_TRUE : FIDO_OPT_FALSE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to %s FIDO user verification: %s", + enable_disable(FLAGS_SET(lock_with, FIDO2ENROLL_UV)), + sym_fido_strerr(r)); + + if (FLAGS_SET(lock_with, FIDO2ENROLL_UV)) + log_notice("%s%sIn order to allow secret key generation, please verify user on security token.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + } + + for (;;) { + bool retry_with_up = false, retry_with_pin = false; + + r = sym_fido_dev_get_assert(d, a, FLAGS_SET(lock_with, FIDO2ENROLL_PIN) ? used_pin : NULL); + + switch (r) { + + case FIDO_ERR_UP_REQUIRED: + /* If the token asks for "up" when we turn off, then this might be a feature that + * isn't optional. Let's enable it */ + + if (!has_up) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for user presence test but doesn't advertise 'up' feature."); + + if (FLAGS_SET(lock_with, FIDO2ENROLL_UP)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for user presence test but was already enabled."); + + log_notice("%s%sLocking without user presence test requested, but FIDO2 device %s requires it, enabling.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : "", + device); + + retry_with_up = true; + break; + + case FIDO_ERR_UNSUPPORTED_OPTION: + /* AuthenTrend ATKey.Pro says it supports "up", but if we disable it it will fail + * with FIDO_ERR_UNSUPPORTED_OPTION, probably because it isn't actually + * optional. Let's see if turning it on works. This is very similar to the + * FIDO_ERR_UP_REQUIRED case, but since the error is so vague we implement it + * slightly more defensively. */ + + if (has_up && !FLAGS_SET(lock_with, FIDO2ENROLL_UP)) { + log_notice("%s%sGot unsupported option error when when user presence test is turned off. Trying with user presence test turned on.", + emoji_enabled() ? special_glyph(SPECIAL_GLYPH_TOUCH) : "", + emoji_enabled() ? " " : ""); + retry_with_up = true; + } + + break; + + case FIDO_ERR_PIN_REQUIRED: + if (!has_client_pin) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for client PIN check but doesn't advertise 'clientPin' feature."); + + if (FLAGS_SET(lock_with, FIDO2ENROLL_PIN)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Token asks for user client PIN check but was already enabled."); + + log_debug("Token requires PIN for assertion, enabling."); + retry_with_pin = true; + break; + + default: + break; + } + + if (!retry_with_up && !retry_with_pin) + break; + + if (retry_with_up) { + r = sym_fido_assert_set_up(a, FIDO_OPT_TRUE); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enable FIDO2 user presence test: %s", sym_fido_strerr(r)); + + lock_with |= FIDO2ENROLL_UP; + } + + if (retry_with_pin) + lock_with |= FIDO2ENROLL_PIN; + } + + if (r == FIDO_ERR_ACTION_TIMEOUT) + return log_error_errno(SYNTHETIC_ERRNO(ENOSTR), + "Token action timeout. (User didn't interact with token quickly enough.)"); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to ask token for assertion: %s", sym_fido_strerr(r)); + + secret = sym_fido_assert_hmac_secret_ptr(a, 0); + if (!secret) + return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to retrieve HMAC secret."); + + secret_size = sym_fido_assert_hmac_secret_len(a, 0); + + secret_copy = memdup(secret, secret_size); + if (!secret_copy) + return log_oom(); + + cid_copy = memdup(cid, cid_size); + if (!cid_copy) + return log_oom(); + + *ret_cid = TAKE_PTR(cid_copy); + *ret_cid_size = cid_size; + *ret_salt = TAKE_PTR(salt); + *ret_salt_size = FIDO2_SALT_SIZE; + *ret_secret = TAKE_PTR(secret_copy); + *ret_secret_size = secret_size; + + if (ret_usedpin) + *ret_usedpin = TAKE_PTR(used_pin); + + if (ret_locked_with) + *ret_locked_with = lock_with; + + return 0; +} +#endif + +#if HAVE_LIBFIDO2 +static int check_device_is_fido2_with_hmac_secret(const char *path) { + _cleanup_(fido_dev_free_wrapper) fido_dev_t *d = NULL; + int r; + + d = sym_fido_dev_new(); + if (!d) + return log_oom(); + + r = sym_fido_dev_open(d, path); + if (r != FIDO_OK) + return log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to open FIDO2 device %s: %s", path, sym_fido_strerr(r)); + + r = verify_features(d, path, LOG_DEBUG, NULL, NULL, NULL, NULL); + if (r == -ENODEV) /* Not a FIDO2 device, or not implementing 'hmac-secret' */ + return false; + if (r < 0) + return r; + + return true; +} +#endif + +int fido2_list_devices(void) { +#if HAVE_LIBFIDO2 + _cleanup_(table_unrefp) Table *t = NULL; + size_t allocated = 64, found = 0; + fido_dev_info_t *di = NULL; + int r; + + r = dlopen_libfido2(); + if (r < 0) + return log_error_errno(r, "FIDO2 token support is not installed."); + + di = sym_fido_dev_info_new(allocated); + if (!di) + return log_oom(); + + r = sym_fido_dev_info_manifest(di, allocated, &found); + if (r == FIDO_ERR_INTERNAL || (r == FIDO_OK && found == 0)) { + /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */ + log_info("No FIDO2 devices found."); + r = 0; + goto finish; + } + if (r != FIDO_OK) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", sym_fido_strerr(r)); + goto finish; + } + + t = table_new("path", "manufacturer", "product"); + if (!t) { + r = log_oom(); + goto finish; + } + + for (size_t i = 0; i < found; i++) { + const fido_dev_info_t *entry; + + entry = sym_fido_dev_info_ptr(di, i); + if (!entry) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to get device information for FIDO device %zu.", i); + goto finish; + } + + r = check_device_is_fido2_with_hmac_secret(sym_fido_dev_info_path(entry)); + if (r < 0) + goto finish; + if (!r) + continue; + + r = table_add_many( + t, + TABLE_PATH, sym_fido_dev_info_path(entry), + TABLE_STRING, sym_fido_dev_info_manufacturer_string(entry), + TABLE_STRING, sym_fido_dev_info_product_string(entry)); + if (r < 0) { + table_log_add_error(r); + goto finish; + } + } + + r = table_print(t, stdout); + if (r < 0) { + log_error_errno(r, "Failed to show device table: %m"); + goto finish; + } + + r = 0; + +finish: + sym_fido_dev_info_free(&di, allocated); + return r; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "FIDO2 tokens not supported on this build."); +#endif +} + +int fido2_find_device_auto(char **ret) { +#if HAVE_LIBFIDO2 + _cleanup_free_ char *copy = NULL; + size_t di_size = 64, found = 0; + const fido_dev_info_t *entry; + fido_dev_info_t *di = NULL; + const char *path; + int r; + + r = dlopen_libfido2(); + if (r < 0) + return log_error_errno(r, "FIDO2 token support is not installed."); + + di = sym_fido_dev_info_new(di_size); + if (!di) + return log_oom(); + + r = sym_fido_dev_info_manifest(di, di_size, &found); + if (r == FIDO_ERR_INTERNAL || (r == FIDO_OK && found == 0)) { + /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */ + r = log_error_errno(SYNTHETIC_ERRNO(ENODEV), "No FIDO devices found."); + goto finish; + } + if (r != FIDO_OK) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO devices: %s", sym_fido_strerr(r)); + goto finish; + } + if (found > 1) { + r = log_error_errno(SYNTHETIC_ERRNO(ENOTUNIQ), "More than one FIDO device found."); + goto finish; + } + + entry = sym_fido_dev_info_ptr(di, 0); + if (!entry) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to get device information for FIDO device 0."); + goto finish; + } + + r = check_device_is_fido2_with_hmac_secret(sym_fido_dev_info_path(entry)); + if (r < 0) + goto finish; + if (!r) { + r = log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "FIDO device discovered does not implement FIDO2 with 'hmac-secret' extension."); + goto finish; + } + + path = sym_fido_dev_info_path(entry); + if (!path) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), + "Failed to query FIDO device path."); + goto finish; + } + + copy = strdup(path); + if (!copy) { + r = log_oom(); + goto finish; + } + + *ret = TAKE_PTR(copy); + r = 0; + +finish: + sym_fido_dev_info_free(&di, di_size); + return r; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "FIDO2 tokens not supported on this build."); +#endif +} + +int fido2_have_device(const char *device) { +#if HAVE_LIBFIDO2 + size_t allocated = 64, found = 0; + fido_dev_info_t *di = NULL; + int r; + + /* Return == 0 if not devices are found, > 0 if at least one is found */ + + r = dlopen_libfido2(); + if (r < 0) + return log_error_errno(r, "FIDO2 support is not installed."); + + if (device) { + if (access(device, F_OK) < 0) { + if (errno == ENOENT) + return 0; + + return log_error_errno(errno, "Failed to determine whether device '%s' exists: %m", device); + } + + return 1; + } + + di = sym_fido_dev_info_new(allocated); + if (!di) + return log_oom(); + + r = sym_fido_dev_info_manifest(di, allocated, &found); + if (r == FIDO_ERR_INTERNAL) { + /* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */ + r = 0; + goto finish; + } + if (r != FIDO_OK) { + r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", sym_fido_strerr(r)); + goto finish; + } + + r = found; + +finish: + sym_fido_dev_info_free(&di, allocated); + return r; +#else + return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), + "FIDO2 tokens not supported on this build."); +#endif +} + +#if HAVE_LIBFIDO2 +int parse_fido2_algorithm(const char *s, int *ret) { + int a; + + assert(s); + + if (streq(s, "es256")) + a = COSE_ES256; + else if (streq(s, "rs256")) + a = COSE_RS256; + else if (streq(s, "eddsa")) + a = COSE_EDDSA; + else + return -EINVAL; + + if (ret) + *ret = a; + return 0; +} +#endif |