1 /*
2 * Copyright (c) 2020 Yubico AB. All rights reserved.
3 * Use of this source code is governed by a BSD-style
4 * license that can be found in the LICENSE file.
5 */
6
7 #include <sys/types.h>
8 #include <sys/uio.h>
9 #include <sys/socket.h>
10
11 #include <linux/nfc.h>
12
13 #include <errno.h>
14 #include <libudev.h>
15 #include <signal.h>
16 #include <unistd.h>
17
18 #include "fido.h"
19 #include "fido/param.h"
20 #include "netlink.h"
21 #include "iso7816.h"
22
23 #define TX_CHUNK_SIZE 240
24
25 static const uint8_t aid[] = { 0xa0, 0x00, 0x00, 0x06, 0x47, 0x2f, 0x00, 0x01 };
26 static const uint8_t v_u2f[] = { 'U', '2', 'F', '_', 'V', '2' };
27 static const uint8_t v_fido[] = { 'F', 'I', 'D', 'O', '_', '2', '_', '0' };
28
29 struct nfc_linux {
30 int fd;
31 uint32_t dev;
32 uint32_t target;
33 sigset_t sigmask;
34 const sigset_t *sigmaskp;
35 struct fido_nl *nl;
36 };
37
38 static int
tx_short_apdu(fido_dev_t * d,const iso7816_header_t * h,const uint8_t * payload,uint8_t payload_len,uint8_t cla_flags)39 tx_short_apdu(fido_dev_t *d, const iso7816_header_t *h, const uint8_t *payload,
40 uint8_t payload_len, uint8_t cla_flags)
41 {
42 uint8_t apdu[5 + UINT8_MAX + 1];
43 uint8_t sw[2];
44 size_t apdu_len;
45 int ok = -1;
46
47 memset(&apdu, 0, sizeof(apdu));
48 apdu[0] = h->cla | cla_flags;
49 apdu[1] = h->ins;
50 apdu[2] = h->p1;
51 apdu[3] = h->p2;
52 apdu[4] = payload_len;
53 memcpy(&apdu[5], payload, payload_len);
54 apdu_len = (size_t)(5 + payload_len + 1);
55
56 if (d->io.write(d->io_handle, apdu, apdu_len) < 0) {
57 fido_log_debug("%s: write", __func__);
58 goto fail;
59 }
60
61 if (cla_flags & 0x10) {
62 if (d->io.read(d->io_handle, sw, sizeof(sw), -1) != 2) {
63 fido_log_debug("%s: read", __func__);
64 goto fail;
65 }
66 if ((sw[0] << 8 | sw[1]) != SW_NO_ERROR) {
67 fido_log_debug("%s: unexpected sw", __func__);
68 goto fail;
69 }
70 }
71
72 ok = 0;
73 fail:
74 explicit_bzero(apdu, sizeof(apdu));
75
76 return (ok);
77 }
78
79 static int
nfc_do_tx(fido_dev_t * d,const uint8_t * apdu_ptr,size_t apdu_len)80 nfc_do_tx(fido_dev_t *d, const uint8_t *apdu_ptr, size_t apdu_len)
81 {
82 iso7816_header_t h;
83
84 if (fido_buf_read(&apdu_ptr, &apdu_len, &h, sizeof(h)) < 0) {
85 fido_log_debug("%s: header", __func__);
86 return (-1);
87 }
88 if (apdu_len < 2) {
89 fido_log_debug("%s: apdu_len %zu", __func__, apdu_len);
90 return (-1);
91 }
92
93 apdu_len -= 2; /* trim le1 le2 */
94
95 while (apdu_len > TX_CHUNK_SIZE) {
96 if (tx_short_apdu(d, &h, apdu_ptr, TX_CHUNK_SIZE, 0x10) < 0) {
97 fido_log_debug("%s: chain", __func__);
98 return (-1);
99 }
100 apdu_ptr += TX_CHUNK_SIZE;
101 apdu_len -= TX_CHUNK_SIZE;
102 }
103
104 if (tx_short_apdu(d, &h, apdu_ptr, (uint8_t)apdu_len, 0) < 0) {
105 fido_log_debug("%s: tx_short_apdu", __func__);
106 return (-1);
107 }
108
109 return (0);
110 }
111
112 int
fido_nfc_tx(fido_dev_t * d,uint8_t cmd,const unsigned char * buf,size_t count)113 fido_nfc_tx(fido_dev_t *d, uint8_t cmd, const unsigned char *buf, size_t count)
114 {
115 iso7816_apdu_t *apdu = NULL;
116 const uint8_t *ptr;
117 size_t len;
118 int ok = -1;
119
120 switch (cmd) {
121 case CTAP_CMD_INIT: /* select */
122 if ((apdu = iso7816_new(0, 0xa4, 0x04, sizeof(aid))) == NULL ||
123 iso7816_add(apdu, aid, sizeof(aid)) < 0) {
124 fido_log_debug("%s: iso7816", __func__);
125 goto fail;
126 }
127 break;
128 case CTAP_CMD_CBOR: /* wrap cbor */
129 if (count > UINT16_MAX || (apdu = iso7816_new(0x80, 0x10, 0x80,
130 (uint16_t)count)) == NULL ||
131 iso7816_add(apdu, buf, count) < 0) {
132 fido_log_debug("%s: iso7816", __func__);
133 goto fail;
134 }
135 break;
136 case CTAP_CMD_MSG: /* already an apdu */
137 break;
138 default:
139 fido_log_debug("%s: cmd=%02x", __func__, cmd);
140 goto fail;
141 }
142
143 if (apdu != NULL) {
144 ptr = iso7816_ptr(apdu);
145 len = iso7816_len(apdu);
146 } else {
147 ptr = buf;
148 len = count;
149 }
150
151 if (nfc_do_tx(d, ptr, len) < 0) {
152 fido_log_debug("%s: nfc_do_tx", __func__);
153 goto fail;
154 }
155
156 ok = 0;
157 fail:
158 iso7816_free(&apdu);
159
160 return (ok);
161 }
162
163 static int
rx_init(fido_dev_t * d,unsigned char * buf,size_t count,int ms)164 rx_init(fido_dev_t *d, unsigned char *buf, size_t count, int ms)
165 {
166 fido_ctap_info_t *attr = (fido_ctap_info_t *)buf;
167 uint8_t f[64];
168 int n;
169
170 if (count != sizeof(*attr)) {
171 fido_log_debug("%s: count=%zu", __func__, count);
172 return (-1);
173 }
174
175 memset(attr, 0, sizeof(*attr));
176
177 if ((n = d->io.read(d->io_handle, f, sizeof(f), ms)) < 2 ||
178 (f[n - 2] << 8 | f[n - 1]) != SW_NO_ERROR) {
179 fido_log_debug("%s: read", __func__);
180 return (-1);
181 }
182
183 n -= 2;
184
185 if (n == sizeof(v_u2f) && memcmp(f, v_u2f, sizeof(v_u2f)) == 0)
186 attr->flags = FIDO_CAP_CBOR;
187 else if (n == sizeof(v_fido) && memcmp(f, v_fido, sizeof(v_fido)) == 0)
188 attr->flags = FIDO_CAP_CBOR | FIDO_CAP_NMSG;
189 else {
190 fido_log_debug("%s: unknown version string", __func__);
191 #ifdef FIDO_FUZZ
192 attr->flags = FIDO_CAP_CBOR | FIDO_CAP_NMSG;
193 #else
194 return (-1);
195 #endif
196 }
197
198 memcpy(&attr->nonce, &d->nonce, sizeof(attr->nonce)); /* XXX */
199
200 return ((int)count);
201 }
202
203 static int
tx_get_response(fido_dev_t * d,uint8_t count)204 tx_get_response(fido_dev_t *d, uint8_t count)
205 {
206 uint8_t apdu[5];
207
208 memset(apdu, 0, sizeof(apdu));
209 apdu[1] = 0xc0; /* GET_RESPONSE */
210 apdu[4] = count;
211
212 if (d->io.write(d->io_handle, apdu, sizeof(apdu)) < 0) {
213 fido_log_debug("%s: write", __func__);
214 return (-1);
215 }
216
217 return (0);
218 }
219
220 static int
rx_apdu(fido_dev_t * d,uint8_t sw[2],unsigned char ** buf,size_t * count,int ms)221 rx_apdu(fido_dev_t *d, uint8_t sw[2], unsigned char **buf, size_t *count, int ms)
222 {
223 uint8_t f[256 + 2];
224 int n, ok = -1;
225
226 if ((n = d->io.read(d->io_handle, f, sizeof(f), ms)) < 2) {
227 fido_log_debug("%s: read", __func__);
228 goto fail;
229 }
230
231 if (fido_buf_write(buf, count, f, (size_t)(n - 2)) < 0) {
232 fido_log_debug("%s: fido_buf_write", __func__);
233 goto fail;
234 }
235
236 memcpy(sw, f + n - 2, 2);
237
238 ok = 0;
239 fail:
240 explicit_bzero(f, sizeof(f));
241
242 return (ok);
243 }
244
245 static int
rx_msg(fido_dev_t * d,unsigned char * buf,size_t count,int ms)246 rx_msg(fido_dev_t *d, unsigned char *buf, size_t count, int ms)
247 {
248 uint8_t sw[2];
249 const size_t bufsiz = count;
250
251 if (rx_apdu(d, sw, &buf, &count, ms) < 0) {
252 fido_log_debug("%s: preamble", __func__);
253 return (-1);
254 }
255
256 while (sw[0] == SW1_MORE_DATA)
257 if (tx_get_response(d, sw[1]) < 0 ||
258 rx_apdu(d, sw, &buf, &count, ms) < 0) {
259 fido_log_debug("%s: chain", __func__);
260 return (-1);
261 }
262
263 if (fido_buf_write(&buf, &count, sw, sizeof(sw)) < 0) {
264 fido_log_debug("%s: sw", __func__);
265 return (-1);
266 }
267
268 if (bufsiz - count > INT_MAX) {
269 fido_log_debug("%s: bufsiz", __func__);
270 return (-1);
271 }
272
273 return ((int)(bufsiz - count));
274 }
275
276 static int
rx_cbor(fido_dev_t * d,unsigned char * buf,size_t count,int ms)277 rx_cbor(fido_dev_t *d, unsigned char *buf, size_t count, int ms)
278 {
279 int r;
280
281 if ((r = rx_msg(d, buf, count, ms)) < 2)
282 return (-1);
283
284 return (r - 2);
285 }
286
287 int
fido_nfc_rx(fido_dev_t * d,uint8_t cmd,unsigned char * buf,size_t count,int ms)288 fido_nfc_rx(fido_dev_t *d, uint8_t cmd, unsigned char *buf, size_t count, int ms)
289 {
290 switch (cmd) {
291 case CTAP_CMD_INIT:
292 return (rx_init(d, buf, count, ms));
293 case CTAP_CMD_CBOR:
294 return (rx_cbor(d, buf, count, ms));
295 case CTAP_CMD_MSG:
296 return (rx_msg(d, buf, count, ms));
297 default:
298 fido_log_debug("%s: cmd=%02x", __func__, cmd);
299 return (-1);
300 }
301 }
302
303 static char *
get_parent_attr(struct udev_device * dev,const char * subsystem,const char * devtype,const char * attr)304 get_parent_attr(struct udev_device *dev, const char *subsystem,
305 const char *devtype, const char *attr)
306 {
307 struct udev_device *parent;
308 const char *value;
309
310 if ((parent = udev_device_get_parent_with_subsystem_devtype(dev,
311 subsystem, devtype)) == NULL || (value =
312 udev_device_get_sysattr_value(parent, attr)) == NULL)
313 return (NULL);
314
315 return (strdup(value));
316 }
317
318 static char *
get_usb_attr(struct udev_device * dev,const char * attr)319 get_usb_attr(struct udev_device *dev, const char *attr)
320 {
321 return (get_parent_attr(dev, "usb", "usb_device", attr));
322 }
323
324 static int
to_int(const char * str,int base)325 to_int(const char *str, int base)
326 {
327 char *ep;
328 long long ll;
329
330 ll = strtoll(str, &ep, base);
331 if (str == ep || *ep != '\0')
332 return (-1);
333 else if (ll == LLONG_MIN && errno == ERANGE)
334 return (-1);
335 else if (ll == LLONG_MAX && errno == ERANGE)
336 return (-1);
337 else if (ll < 0 || ll > INT_MAX)
338 return (-1);
339
340 return ((int)ll);
341 }
342
343 static int
copy_info(fido_dev_info_t * di,struct udev * udev,struct udev_list_entry * udev_entry)344 copy_info(fido_dev_info_t *di, struct udev *udev,
345 struct udev_list_entry *udev_entry)
346 {
347 const char *name;
348 char *str;
349 struct udev_device *dev = NULL;
350 int id, ok = -1;
351
352 memset(di, 0, sizeof(*di));
353
354 if ((name = udev_list_entry_get_name(udev_entry)) == NULL ||
355 (dev = udev_device_new_from_syspath(udev, name)) == NULL)
356 goto fail;
357
358 if ((di->path = strdup(name)) == NULL ||
359 (di->manufacturer = get_usb_attr(dev, "manufacturer")) == NULL ||
360 (di->product = get_usb_attr(dev, "product")) == NULL)
361 goto fail;
362
363 /* XXX assumes USB for vendor/product info */
364 if ((str = get_usb_attr(dev, "idVendor")) != NULL &&
365 (id = to_int(str, 16)) > 0 && id <= UINT16_MAX)
366 di->vendor_id = (int16_t)id;
367 free(str);
368
369 if ((str = get_usb_attr(dev, "idProduct")) != NULL &&
370 (id = to_int(str, 16)) > 0 && id <= UINT16_MAX)
371 di->product_id = (int16_t)id;
372 free(str);
373
374 ok = 0;
375 fail:
376 if (dev != NULL)
377 udev_device_unref(dev);
378
379 if (ok < 0) {
380 free(di->path);
381 free(di->manufacturer);
382 free(di->product);
383 explicit_bzero(di, sizeof(*di));
384 }
385
386 return (ok);
387 }
388
389 static int
sysnum_from_syspath(const char * path)390 sysnum_from_syspath(const char *path)
391 {
392 struct udev *udev = NULL;
393 struct udev_device *dev = NULL;
394 const char *str;
395 int idx;
396
397 if ((udev = udev_new()) == NULL ||
398 (dev = udev_device_new_from_syspath(udev, path)) == NULL ||
399 (str = udev_device_get_sysnum(dev)) == NULL)
400 idx = -1;
401 else
402 idx = to_int(str, 10);
403
404 if (dev != NULL)
405 udev_device_unref(dev);
406 if (udev != NULL)
407 udev_unref(udev);
408
409 return (idx);
410 }
411
412 int
fido_nfc_manifest(fido_dev_info_t * devlist,size_t ilen,size_t * olen)413 fido_nfc_manifest(fido_dev_info_t *devlist, size_t ilen, size_t *olen)
414 {
415 struct udev *udev = NULL;
416 struct udev_enumerate *udev_enum = NULL;
417 struct udev_list_entry *udev_list;
418 struct udev_list_entry *udev_entry;
419 int r = FIDO_ERR_INTERNAL;
420
421 *olen = 0;
422
423 if (ilen == 0)
424 return (FIDO_OK);
425
426 if (devlist == NULL)
427 return (FIDO_ERR_INVALID_ARGUMENT);
428
429 if ((udev = udev_new()) == NULL ||
430 (udev_enum = udev_enumerate_new(udev)) == NULL)
431 goto fail;
432
433 if (udev_enumerate_add_match_subsystem(udev_enum, "nfc") < 0 ||
434 udev_enumerate_scan_devices(udev_enum) < 0)
435 goto fail;
436
437 if ((udev_list = udev_enumerate_get_list_entry(udev_enum)) == NULL) {
438 r = FIDO_OK; /* zero nfc devices */
439 goto fail;
440 }
441
442 udev_list_entry_foreach(udev_entry, udev_list) {
443 if (copy_info(&devlist[*olen], udev, udev_entry) == 0) {
444 devlist[*olen].io = (fido_dev_io_t) {
445 fido_nfc_open,
446 fido_nfc_close,
447 fido_nfc_read,
448 fido_nfc_write,
449 };
450 devlist[*olen].transport = (fido_dev_transport_t) {
451 fido_nfc_rx,
452 fido_nfc_tx,
453 };
454 if (++(*olen) == ilen)
455 break;
456 }
457 }
458
459 r = FIDO_OK;
460 fail:
461 if (udev_enum != NULL)
462 udev_enumerate_unref(udev_enum);
463 if (udev != NULL)
464 udev_unref(udev);
465
466 return (r);
467 }
468
469 static int
nfc_target_connect(struct nfc_linux * ctx)470 nfc_target_connect(struct nfc_linux *ctx)
471 {
472 struct sockaddr_nfc sa;
473
474 memset(&sa, 0, sizeof(sa));
475 sa.sa_family = AF_NFC;
476 sa.dev_idx = ctx->dev;
477 sa.target_idx = ctx->target;
478 sa.nfc_protocol = NFC_PROTO_ISO14443;
479
480 if ((ctx->fd = socket(AF_NFC, SOCK_SEQPACKET | SOCK_CLOEXEC,
481 NFC_SOCKPROTO_RAW)) == -1) {
482 fido_log_error(errno, "%s: socket", __func__);
483 return (-1);
484 }
485 if (connect(ctx->fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
486 fido_log_error(errno, "%s: connect", __func__);
487 if (close(ctx->fd) == -1)
488 fido_log_error(errno, "%s: close", __func__);
489 ctx->fd = -1;
490 return (-1);
491 }
492
493 return (0);
494 }
495
496 static void
nfc_free(struct nfc_linux ** ctx_p)497 nfc_free(struct nfc_linux **ctx_p)
498 {
499 struct nfc_linux *ctx;
500
501 if (ctx_p == NULL || (ctx = *ctx_p) == NULL)
502 return;
503 if (ctx->fd != -1 && close(ctx->fd) == -1)
504 fido_log_error(errno, "%s: close", __func__);
505 if (ctx->nl != NULL)
506 fido_nl_free(&ctx->nl);
507
508 free(ctx);
509 *ctx_p = NULL;
510 }
511
512 static struct nfc_linux *
nfc_new(uint32_t dev)513 nfc_new(uint32_t dev)
514 {
515 struct nfc_linux *ctx;
516
517 if ((ctx = calloc(1, sizeof(*ctx))) == NULL ||
518 (ctx->nl = fido_nl_new()) == NULL) {
519 nfc_free(&ctx);
520 return (NULL);
521 }
522
523 ctx->fd = -1;
524 ctx->dev = dev;
525
526 return (ctx);
527 }
528
529 void *
fido_nfc_open(const char * path)530 fido_nfc_open(const char *path)
531 {
532 struct nfc_linux *ctx = NULL;
533 int idx;
534
535 if ((idx = sysnum_from_syspath(path)) < 0 ||
536 (ctx = nfc_new((uint32_t)idx)) == NULL) {
537 fido_log_debug("%s: nfc_new", __func__);
538 goto fail;
539 }
540 if (fido_nl_power_nfc(ctx->nl, ctx->dev) < 0 ||
541 fido_nl_get_nfc_target(ctx->nl, ctx->dev, &ctx->target) < 0 ||
542 nfc_target_connect(ctx) < 0) {
543 fido_log_debug("%s: netlink", __func__);
544 goto fail;
545 }
546
547 return (ctx);
548 fail:
549 nfc_free(&ctx);
550 return (NULL);
551 }
552
553 void
fido_nfc_close(void * handle)554 fido_nfc_close(void *handle)
555 {
556 struct nfc_linux *ctx = handle;
557
558 nfc_free(&ctx);
559 }
560
561 int
fido_nfc_set_sigmask(void * handle,const fido_sigset_t * sigmask)562 fido_nfc_set_sigmask(void *handle, const fido_sigset_t *sigmask)
563 {
564 struct nfc_linux *ctx = handle;
565
566 ctx->sigmask = *sigmask;
567 ctx->sigmaskp = &ctx->sigmask;
568
569 return (FIDO_OK);
570 }
571
572 int
fido_nfc_read(void * handle,unsigned char * buf,size_t len,int ms)573 fido_nfc_read(void *handle, unsigned char *buf, size_t len, int ms)
574 {
575 struct nfc_linux *ctx = handle;
576 struct iovec iov[2];
577 uint8_t preamble;
578 ssize_t r;
579
580 memset(&iov, 0, sizeof(iov));
581 iov[0].iov_base = &preamble;
582 iov[0].iov_len = sizeof(preamble);
583 iov[1].iov_base = buf;
584 iov[1].iov_len = len;
585
586 if (fido_hid_unix_wait(ctx->fd, ms, ctx->sigmaskp) < 0) {
587 fido_log_debug("%s: fido_hid_unix_wait", __func__);
588 return (-1);
589 }
590 if ((r = readv(ctx->fd, iov, nitems(iov))) == -1) {
591 fido_log_error(errno, "%s: read", __func__);
592 return (-1);
593 }
594 if (r < 1) {
595 fido_log_debug("%s: %zd < 1", __func__, r);
596 return (-1);
597 }
598 if (preamble != 0x00) {
599 fido_log_debug("%s: preamble", __func__);
600 return (-1);
601 }
602
603 r--;
604 fido_log_xxd(buf, (size_t)r, "%s", __func__);
605
606 return ((int)r);
607 }
608
609 int
fido_nfc_write(void * handle,const unsigned char * buf,size_t len)610 fido_nfc_write(void *handle, const unsigned char *buf, size_t len)
611 {
612 struct nfc_linux *ctx = handle;
613 ssize_t r;
614
615 fido_log_xxd(buf, len, "%s", __func__);
616
617 if (len > INT_MAX) {
618 fido_log_debug("%s: len", __func__);
619 return (-1);
620 }
621 if ((r = write(ctx->fd, buf, len)) == -1) {
622 fido_log_error(errno, "%s: write", __func__);
623 return (-1);
624 }
625 if (r < 0 || (size_t)r != len) {
626 fido_log_debug("%s: %zd != %zu", __func__, r, len);
627 return (-1);
628 }
629
630 return ((int)r);
631 }
632