203 lines
8.1 KiB
C
203 lines
8.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <fido.h>
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#include "hexdecoct.h"
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#include "homework-fido2.h"
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#include "libfido2-util.h"
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#include "strv.h"
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static int fido2_use_specific_token(
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const char *path,
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UserRecord *h,
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UserRecord *secret,
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const Fido2HmacSalt *salt,
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char **ret) {
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_cleanup_(fido_cbor_info_free_wrapper) fido_cbor_info_t *di = NULL;
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_cleanup_(fido_assert_free_wrapper) fido_assert_t *a = NULL;
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_cleanup_(fido_dev_free_wrapper) fido_dev_t *d = NULL;
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bool found_extension = false;
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size_t n, hmac_size;
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const void *hmac;
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char **e;
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int r;
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d = sym_fido_dev_new();
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if (!d)
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return log_oom();
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r = sym_fido_dev_open(d, path);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to open FIDO2 device %s: %s", path, sym_fido_strerr(r));
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if (!sym_fido_dev_is_fido2(d))
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return log_error_errno(SYNTHETIC_ERRNO(ENODEV),
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"Specified device %s is not a FIDO2 device.", path);
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di = sym_fido_cbor_info_new();
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if (!di)
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return log_oom();
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r = sym_fido_dev_get_cbor_info(d, di);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to get CBOR device info for %s: %s", path, sym_fido_strerr(r));
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e = sym_fido_cbor_info_extensions_ptr(di);
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n = sym_fido_cbor_info_extensions_len(di);
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for (size_t i = 0; i < n; i++)
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if (streq(e[i], "hmac-secret")) {
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found_extension = true;
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break;
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}
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if (!found_extension)
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return log_error_errno(SYNTHETIC_ERRNO(ENODEV),
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"Specified device %s is a FIDO2 device, but does not support the required HMAC-SECRET extension.", path);
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a = sym_fido_assert_new();
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if (!a)
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return log_oom();
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r = sym_fido_assert_set_extensions(a, FIDO_EXT_HMAC_SECRET);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to enable HMAC-SECRET extension on FIDO2 assertion: %s", sym_fido_strerr(r));
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r = sym_fido_assert_set_hmac_salt(a, salt->salt, salt->salt_size);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to set salt on FIDO2 assertion: %s", sym_fido_strerr(r));
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r = sym_fido_assert_set_rp(a, "io.systemd.home");
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to set FIDO2 assertion ID: %s", sym_fido_strerr(r));
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r = sym_fido_assert_set_clientdata_hash(a, (const unsigned char[32]) {}, 32);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to set FIDO2 assertion client data hash: %s", sym_fido_strerr(r));
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r = sym_fido_assert_allow_cred(a, salt->credential.id, salt->credential.size);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to add FIDO2 assertion credential ID: %s", sym_fido_strerr(r));
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r = sym_fido_assert_set_up(a, h->fido2_user_presence_permitted <= 0 ? FIDO_OPT_FALSE : FIDO_OPT_TRUE);
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if (r != FIDO_OK)
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to set FIDO2 assertion user presence: %s", sym_fido_strerr(r));
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log_info("Asking FIDO2 token for authentication.");
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r = sym_fido_dev_get_assert(d, a, NULL); /* try without pin first */
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if (r == FIDO_ERR_PIN_REQUIRED) {
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char **i;
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/* OK, we needed a pin, try with all pins in turn */
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STRV_FOREACH(i, secret->token_pin) {
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r = sym_fido_dev_get_assert(d, a, *i);
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if (r != FIDO_ERR_PIN_INVALID)
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break;
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}
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}
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switch (r) {
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case FIDO_OK:
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break;
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case FIDO_ERR_NO_CREDENTIALS:
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return log_error_errno(SYNTHETIC_ERRNO(EBADSLT),
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"Wrong security token; needed credentials not present on token.");
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case FIDO_ERR_PIN_REQUIRED:
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return log_error_errno(SYNTHETIC_ERRNO(ENOANO),
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"Security token requires PIN.");
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case FIDO_ERR_PIN_AUTH_BLOCKED:
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return log_error_errno(SYNTHETIC_ERRNO(EOWNERDEAD),
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"PIN of security token is blocked, please remove/reinsert token.");
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case FIDO_ERR_PIN_INVALID:
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return log_error_errno(SYNTHETIC_ERRNO(ENOLCK),
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"PIN of security token incorrect.");
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case FIDO_ERR_UP_REQUIRED:
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return log_error_errno(SYNTHETIC_ERRNO(EMEDIUMTYPE),
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"User presence required.");
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case FIDO_ERR_ACTION_TIMEOUT:
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return log_error_errno(SYNTHETIC_ERRNO(ENOSTR),
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"Token action timeout. (User didn't interact with token quickly enough.)");
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default:
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return log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to ask token for assertion: %s", sym_fido_strerr(r));
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}
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hmac = sym_fido_assert_hmac_secret_ptr(a, 0);
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if (!hmac)
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return log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to retrieve HMAC secret.");
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hmac_size = sym_fido_assert_hmac_secret_len(a, 0);
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r = base64mem(hmac, hmac_size, ret);
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if (r < 0)
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return log_error_errno(r, "Failed to base64 encode HMAC secret: %m");
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return 0;
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}
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int fido2_use_token(UserRecord *h, UserRecord *secret, const Fido2HmacSalt *salt, char **ret) {
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size_t allocated = 64, found = 0;
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fido_dev_info_t *di = NULL;
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int r;
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r = dlopen_libfido2();
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if (r < 0)
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return log_error_errno(r, "FIDO2 support is not installed.");
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di = sym_fido_dev_info_new(allocated);
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if (!di)
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return log_oom();
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r = sym_fido_dev_info_manifest(di, allocated, &found);
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if (r == FIDO_ERR_INTERNAL) {
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/* The library returns FIDO_ERR_INTERNAL when no devices are found. I wish it wouldn't. */
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r = log_debug_errno(SYNTHETIC_ERRNO(EAGAIN), "Got FIDO_ERR_INTERNAL, assuming no devices.");
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goto finish;
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}
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if (r != FIDO_OK) {
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r = log_error_errno(SYNTHETIC_ERRNO(EIO), "Failed to enumerate FIDO2 devices: %s", sym_fido_strerr(r));
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goto finish;
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}
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for (size_t i = 0; i < found; i++) {
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const fido_dev_info_t *entry;
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const char *path;
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entry = sym_fido_dev_info_ptr(di, i);
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if (!entry) {
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r = log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to get device information for FIDO device %zu.", i);
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goto finish;
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}
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path = sym_fido_dev_info_path(entry);
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if (!path) {
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r = log_error_errno(SYNTHETIC_ERRNO(EIO),
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"Failed to query FIDO device path.");
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goto finish;
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}
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r = fido2_use_specific_token(path, h, secret, salt, ret);
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if (!IN_SET(r,
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-EBADSLT, /* device doesn't understand our credential hash */
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-ENODEV /* device is not a FIDO2 device with HMAC-SECRET */))
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goto finish;
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}
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r = -EAGAIN;
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finish:
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sym_fido_dev_info_free(&di, allocated);
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return r;
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}
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