1 /*
2 * Copyright (c) 2020-2022 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 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8 #include <sys/types.h>
9 #include <sys/uio.h>
10 #include <sys/socket.h>
11
12 #include <linux/nfc.h>
13
14 #include <errno.h>
15 #include <libudev.h>
16 #include <signal.h>
17 #include <stdio.h>
18 #include <string.h>
19 #include <unistd.h>
20
21 #include "fido.h"
22 #include "fido/param.h"
23 #include "netlink.h"
24 #include "iso7816.h"
25
26 struct nfc_linux {
27 int fd;
28 uint32_t dev;
29 uint32_t target;
30 sigset_t sigmask;
31 const sigset_t *sigmaskp;
32 struct fido_nl *nl;
33 };
34
35 static char *
get_parent_attr(struct udev_device * dev,const char * subsystem,const char * devtype,const char * attr)36 get_parent_attr(struct udev_device *dev, const char *subsystem,
37 const char *devtype, const char *attr)
38 {
39 struct udev_device *parent;
40 const char *value;
41
42 if ((parent = udev_device_get_parent_with_subsystem_devtype(dev,
43 subsystem, devtype)) == NULL || (value =
44 udev_device_get_sysattr_value(parent, attr)) == NULL)
45 return NULL;
46
47 return strdup(value);
48 }
49
50 static char *
get_usb_attr(struct udev_device * dev,const char * attr)51 get_usb_attr(struct udev_device *dev, const char *attr)
52 {
53 return get_parent_attr(dev, "usb", "usb_device", attr);
54 }
55
56 static int
copy_info(fido_dev_info_t * di,struct udev * udev,struct udev_list_entry * udev_entry)57 copy_info(fido_dev_info_t *di, struct udev *udev,
58 struct udev_list_entry *udev_entry)
59 {
60 const char *name;
61 char *str;
62 struct udev_device *dev = NULL;
63 uint64_t id;
64 int ok = -1;
65
66 memset(di, 0, sizeof(*di));
67
68 if ((name = udev_list_entry_get_name(udev_entry)) == NULL ||
69 (dev = udev_device_new_from_syspath(udev, name)) == NULL)
70 goto fail;
71 if (asprintf(&di->path, "%s/%s", FIDO_NFC_PREFIX, name) == -1) {
72 di->path = NULL;
73 goto fail;
74 }
75 if (nfc_is_fido(di->path) == false) {
76 fido_log_debug("%s: nfc_is_fido: %s", __func__, di->path);
77 goto fail;
78 }
79 if ((di->manufacturer = get_usb_attr(dev, "manufacturer")) == NULL)
80 di->manufacturer = strdup("");
81 if ((di->product = get_usb_attr(dev, "product")) == NULL)
82 di->product = strdup("");
83 if (di->manufacturer == NULL || di->product == NULL)
84 goto fail;
85 /* XXX assumes USB for vendor/product info */
86 if ((str = get_usb_attr(dev, "idVendor")) != NULL &&
87 fido_to_uint64(str, 16, &id) == 0 && id <= UINT16_MAX)
88 di->vendor_id = (int16_t)id;
89 free(str);
90 if ((str = get_usb_attr(dev, "idProduct")) != NULL &&
91 fido_to_uint64(str, 16, &id) == 0 && id <= UINT16_MAX)
92 di->product_id = (int16_t)id;
93 free(str);
94
95 ok = 0;
96 fail:
97 if (dev != NULL)
98 udev_device_unref(dev);
99
100 if (ok < 0) {
101 free(di->path);
102 free(di->manufacturer);
103 free(di->product);
104 explicit_bzero(di, sizeof(*di));
105 }
106
107 return ok;
108 }
109
110 static int
sysnum_from_syspath(const char * path)111 sysnum_from_syspath(const char *path)
112 {
113 struct udev *udev = NULL;
114 struct udev_device *dev = NULL;
115 const char *str;
116 uint64_t idx64;
117 int idx = -1;
118
119 if ((udev = udev_new()) != NULL &&
120 (dev = udev_device_new_from_syspath(udev, path)) != NULL &&
121 (str = udev_device_get_sysnum(dev)) != NULL &&
122 fido_to_uint64(str, 10, &idx64) == 0 && idx64 < INT_MAX)
123 idx = (int)idx64;
124
125 if (dev != NULL)
126 udev_device_unref(dev);
127 if (udev != NULL)
128 udev_unref(udev);
129
130 return idx;
131 }
132
133 int
fido_nfc_manifest(fido_dev_info_t * devlist,size_t ilen,size_t * olen)134 fido_nfc_manifest(fido_dev_info_t *devlist, size_t ilen, size_t *olen)
135 {
136 struct udev *udev = NULL;
137 struct udev_enumerate *udev_enum = NULL;
138 struct udev_list_entry *udev_list;
139 struct udev_list_entry *udev_entry;
140 int r = FIDO_ERR_INTERNAL;
141
142 *olen = 0;
143
144 if (ilen == 0)
145 return FIDO_OK;
146
147 if (devlist == NULL)
148 return FIDO_ERR_INVALID_ARGUMENT;
149
150 if ((udev = udev_new()) == NULL ||
151 (udev_enum = udev_enumerate_new(udev)) == NULL)
152 goto fail;
153
154 if (udev_enumerate_add_match_subsystem(udev_enum, "nfc") < 0 ||
155 udev_enumerate_scan_devices(udev_enum) < 0)
156 goto fail;
157
158 if ((udev_list = udev_enumerate_get_list_entry(udev_enum)) == NULL) {
159 r = FIDO_OK; /* zero nfc devices */
160 goto fail;
161 }
162
163 udev_list_entry_foreach(udev_entry, udev_list) {
164 if (copy_info(&devlist[*olen], udev, udev_entry) == 0) {
165 devlist[*olen].io = (fido_dev_io_t) {
166 fido_nfc_open,
167 fido_nfc_close,
168 fido_nfc_read,
169 fido_nfc_write,
170 };
171 devlist[*olen].transport = (fido_dev_transport_t) {
172 fido_nfc_rx,
173 fido_nfc_tx,
174 };
175 if (++(*olen) == ilen)
176 break;
177 }
178 }
179
180 r = FIDO_OK;
181 fail:
182 if (udev_enum != NULL)
183 udev_enumerate_unref(udev_enum);
184 if (udev != NULL)
185 udev_unref(udev);
186
187 return r;
188 }
189
190 static int
nfc_target_connect(struct nfc_linux * ctx)191 nfc_target_connect(struct nfc_linux *ctx)
192 {
193 struct sockaddr_nfc sa;
194
195 memset(&sa, 0, sizeof(sa));
196 sa.sa_family = AF_NFC;
197 sa.dev_idx = ctx->dev;
198 sa.target_idx = ctx->target;
199 sa.nfc_protocol = NFC_PROTO_ISO14443;
200
201 if ((ctx->fd = socket(AF_NFC, SOCK_SEQPACKET | SOCK_CLOEXEC,
202 NFC_SOCKPROTO_RAW)) == -1) {
203 fido_log_error(errno, "%s: socket", __func__);
204 return -1;
205 }
206 if (connect(ctx->fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
207 fido_log_error(errno, "%s: connect", __func__);
208 if (close(ctx->fd) == -1)
209 fido_log_error(errno, "%s: close", __func__);
210 ctx->fd = -1;
211 return -1;
212 }
213
214 return 0;
215 }
216
217 static void
nfc_free(struct nfc_linux ** ctx_p)218 nfc_free(struct nfc_linux **ctx_p)
219 {
220 struct nfc_linux *ctx;
221
222 if (ctx_p == NULL || (ctx = *ctx_p) == NULL)
223 return;
224 if (ctx->fd != -1 && close(ctx->fd) == -1)
225 fido_log_error(errno, "%s: close", __func__);
226 if (ctx->nl != NULL)
227 fido_nl_free(&ctx->nl);
228
229 free(ctx);
230 *ctx_p = NULL;
231 }
232
233 static struct nfc_linux *
nfc_new(uint32_t dev)234 nfc_new(uint32_t dev)
235 {
236 struct nfc_linux *ctx;
237
238 if ((ctx = calloc(1, sizeof(*ctx))) == NULL ||
239 (ctx->nl = fido_nl_new()) == NULL) {
240 nfc_free(&ctx);
241 return NULL;
242 }
243
244 ctx->fd = -1;
245 ctx->dev = dev;
246
247 return ctx;
248 }
249
250 void *
fido_nfc_open(const char * path)251 fido_nfc_open(const char *path)
252 {
253 struct nfc_linux *ctx = NULL;
254 int idx;
255
256 if (strncmp(path, FIDO_NFC_PREFIX, strlen(FIDO_NFC_PREFIX)) != 0) {
257 fido_log_debug("%s: bad prefix", __func__);
258 goto fail;
259 }
260 if ((idx = sysnum_from_syspath(path + strlen(FIDO_NFC_PREFIX))) < 0 ||
261 (ctx = nfc_new((uint32_t)idx)) == NULL) {
262 fido_log_debug("%s: nfc_new", __func__);
263 goto fail;
264 }
265 if (fido_nl_power_nfc(ctx->nl, ctx->dev) < 0 ||
266 fido_nl_get_nfc_target(ctx->nl, ctx->dev, &ctx->target) < 0 ||
267 nfc_target_connect(ctx) < 0) {
268 fido_log_debug("%s: netlink", __func__);
269 goto fail;
270 }
271
272 return ctx;
273 fail:
274 nfc_free(&ctx);
275 return NULL;
276 }
277
278 void
fido_nfc_close(void * handle)279 fido_nfc_close(void *handle)
280 {
281 struct nfc_linux *ctx = handle;
282
283 nfc_free(&ctx);
284 }
285
286 int
fido_nfc_set_sigmask(void * handle,const fido_sigset_t * sigmask)287 fido_nfc_set_sigmask(void *handle, const fido_sigset_t *sigmask)
288 {
289 struct nfc_linux *ctx = handle;
290
291 ctx->sigmask = *sigmask;
292 ctx->sigmaskp = &ctx->sigmask;
293
294 return FIDO_OK;
295 }
296
297 int
fido_nfc_read(void * handle,unsigned char * buf,size_t len,int ms)298 fido_nfc_read(void *handle, unsigned char *buf, size_t len, int ms)
299 {
300 struct nfc_linux *ctx = handle;
301 struct iovec iov[2];
302 uint8_t preamble;
303 ssize_t r;
304
305 memset(&iov, 0, sizeof(iov));
306 iov[0].iov_base = &preamble;
307 iov[0].iov_len = sizeof(preamble);
308 iov[1].iov_base = buf;
309 iov[1].iov_len = len;
310
311 if (fido_hid_unix_wait(ctx->fd, ms, ctx->sigmaskp) < 0) {
312 fido_log_debug("%s: fido_hid_unix_wait", __func__);
313 return -1;
314 }
315 if ((r = readv(ctx->fd, iov, nitems(iov))) == -1) {
316 fido_log_error(errno, "%s: read", __func__);
317 return -1;
318 }
319 if (r < 1) {
320 fido_log_debug("%s: %zd < 1", __func__, r);
321 return -1;
322 }
323 if (preamble != 0x00) {
324 fido_log_debug("%s: preamble", __func__);
325 return -1;
326 }
327
328 r--;
329 fido_log_xxd(buf, (size_t)r, "%s", __func__);
330
331 return (int)r;
332 }
333
334 int
fido_nfc_write(void * handle,const unsigned char * buf,size_t len)335 fido_nfc_write(void *handle, const unsigned char *buf, size_t len)
336 {
337 struct nfc_linux *ctx = handle;
338 ssize_t r;
339
340 fido_log_xxd(buf, len, "%s", __func__);
341
342 if (len > INT_MAX) {
343 fido_log_debug("%s: len", __func__);
344 return -1;
345 }
346 if ((r = write(ctx->fd, buf, len)) == -1) {
347 fido_log_error(errno, "%s: write", __func__);
348 return -1;
349 }
350 if (r < 0 || (size_t)r != len) {
351 fido_log_debug("%s: %zd != %zu", __func__, r, len);
352 return -1;
353 }
354
355 return (int)r;
356 }
357