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mirror of https://git.kernel.org/pub/scm/network/wireless/iwd.git synced 2024-12-22 13:02:44 +01:00

dpp: send presence announcements on StartEnrollee

The presence procedure implemented is a far cry from what the spec
actually wants. There are two reason for this: a) the kernels offchannel
support is not at a level where it will work without rather annoying
work arounds, and b) doing the procedure outlined in the spec will
result in terrible discovery performance.

Because of this a simpler single channel announcement is done by default
and the full presence procedure is left out until/if it is needed.
This commit is contained in:
James Prestwood 2021-12-16 10:08:49 -08:00 committed by Denis Kenzior
parent 76d9a2e702
commit 683d3a3f04

243
src/dpp.c
View File

@ -24,15 +24,32 @@
#include <config.h>
#endif
#include <errno.h>
#include <ell/ell.h>
#include "linux/nl80211.h"
#include "src/dbus.h"
#include "src/netdev.h"
#include "src/module.h"
#include "src/dpp-util.h"
#include "src/band.h"
#include "src/frame-xchg.h"
#include "src/offchannel.h"
#include "src/wiphy.h"
#include "src/ie.h"
#include "src/iwd.h"
#include "src/util.h"
static uint32_t netdev_watch;
static struct l_genl_family *nl80211;
static uint8_t broadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
enum dpp_state {
DPP_STATE_NOTHING,
DPP_STATE_PRESENCE,
};
struct dpp_sm {
struct netdev *netdev;
@ -48,6 +65,17 @@ struct dpp_sm {
size_t nonce_len;
struct l_ecc_scalar *boot_private;
struct l_ecc_point *boot_public;
enum dpp_state state;
uint32_t *freqs;
size_t freqs_len;
size_t freqs_idx;
uint32_t dwell;
uint32_t current_freq;
struct scan_freq_set *presence_list;
uint32_t offchannel_id;
};
static void dpp_reset(struct dpp_sm *dpp)
@ -56,6 +84,18 @@ static void dpp_reset(struct dpp_sm *dpp)
l_free(dpp->uri);
dpp->uri = NULL;
}
if (dpp->freqs) {
l_free(dpp->freqs);
dpp->freqs = NULL;
}
if (dpp->offchannel_id) {
offchannel_cancel(dpp->wdev_id, dpp->offchannel_id);
dpp->offchannel_id = 0;
}
dpp->state = DPP_STATE_NOTHING;
}
static void dpp_free(struct dpp_sm *dpp)
@ -80,12 +120,106 @@ static void dpp_free(struct dpp_sm *dpp)
l_free(dpp);
}
static void dpp_send_frame_cb(struct l_genl_msg *msg, void *user_data)
{
if (l_genl_msg_get_error(msg) < 0)
l_error("Error sending frame");
}
static void dpp_send_frame(uint64_t wdev_id, struct iovec *iov, size_t iov_len,
uint32_t freq)
{
struct l_genl_msg *msg;
msg = l_genl_msg_new_sized(NL80211_CMD_FRAME, 512);
l_genl_msg_append_attr(msg, NL80211_ATTR_WDEV, 8, &wdev_id);
l_genl_msg_append_attr(msg, NL80211_ATTR_WIPHY_FREQ, 4, &freq);
l_genl_msg_append_attr(msg, NL80211_ATTR_OFFCHANNEL_TX_OK, 0, NULL);
l_genl_msg_append_attrv(msg, NL80211_ATTR_FRAME, iov, iov_len);
l_debug("Sending frame on frequency %u", freq);
if (!l_genl_family_send(nl80211, msg, dpp_send_frame_cb, NULL, NULL))
l_error("Could not send CMD_FRAME");
}
static size_t dpp_append_attr(uint8_t *to, enum dpp_attribute_type type,
void *attr, size_t attr_len)
{
l_put_le16(type, to);
l_put_le16(attr_len, to + 2);
memcpy(to + 4, attr, attr_len);
return attr_len + 4;
}
static size_t dpp_build_header(const uint8_t *src, const uint8_t *dest,
enum dpp_frame_type type,
uint8_t buf[static 32])
{
uint8_t *ptr = buf + 24;
memset(buf, 0, 32);
l_put_le16(0x00d0, buf);
memcpy(buf + 4, dest, 6);
memcpy(buf + 10, src, 6);
memcpy(buf + 16, broadcast, 6);
*ptr++ = 0x04; /* Category: Public */
*ptr++ = 0x09; /* Action: Vendor specific usage */
memcpy(ptr, wifi_alliance_oui, 3);
ptr += 3;
*ptr++ = 0x1a; /* WiFi Alliance DPP OI type */
*ptr++ = 1; /* Cryptosuite */
*ptr++ = type;
return ptr - buf;
}
static void dpp_presence_announce(struct dpp_sm *dpp)
{
struct netdev *netdev = dpp->netdev;
uint8_t hdr[32];
uint8_t attrs[32 + 4];
uint8_t hash[32];
uint8_t *ptr = attrs;
const uint8_t *addr = netdev_get_address(netdev);
struct iovec iov[2];
iov[0].iov_len = dpp_build_header(addr, broadcast,
DPP_FRAME_PRESENCE_ANNOUNCEMENT, hdr);
iov[0].iov_base = hdr;
dpp_hash(L_CHECKSUM_SHA256, hash, 2, "chirp", strlen("chirp"),
dpp->pub_asn1, dpp->pub_asn1_len);
ptr += dpp_append_attr(ptr, DPP_ATTR_RESPONDER_BOOT_KEY_HASH, hash, 32);
iov[1].iov_base = attrs;
iov[1].iov_len = ptr - attrs;
l_debug("Sending presense annoucement on frequency %u and waiting %u",
dpp->current_freq, dpp->dwell);
dpp_send_frame(netdev_get_wdev_id(netdev), iov, 2, dpp->current_freq);
}
static void dpp_roc_started(void *user_data)
{
struct dpp_sm *dpp = user_data;
dpp_presence_announce(dpp);
}
static void dpp_create(struct netdev *netdev)
{
struct l_dbus *dbus = dbus_get_bus();
struct dpp_sm *dpp = l_new(struct dpp_sm, 1);
dpp->netdev = netdev;
dpp->state = DPP_STATE_NOTHING;
dpp->wdev_id = netdev_get_wdev_id(netdev);
dpp->curve = l_ecc_curve_from_ike_group(19);
dpp->key_len = l_ecc_curve_get_scalar_bytes(dpp->curve);
dpp->nonce_len = dpp_nonce_len_from_key_len(dpp->key_len);
@ -123,6 +257,97 @@ static void dpp_netdev_watch(struct netdev *netdev,
}
}
static void dpp_presence_timeout(int error, void *user_data)
{
struct dpp_sm *dpp = user_data;
if (dpp->state != DPP_STATE_PRESENCE) {
l_debug("DPP state changed, stopping presence announcements");
dpp->freqs_idx = 0;
return;
}
dpp->freqs_idx++;
if (dpp->freqs_idx >= dpp->freqs_len) {
l_debug("Max retries on presence announcements");
dpp->freqs_idx = 0;
}
dpp->current_freq = dpp->freqs[dpp->freqs_idx];
l_debug("Presence timeout, moving to next frequency %u, duration %u",
dpp->current_freq, dpp->dwell);
dpp->offchannel_id = offchannel_start(netdev_get_wdev_id(dpp->netdev),
dpp->current_freq, dpp->dwell, dpp_roc_started,
dpp, dpp_presence_timeout);
}
/*
* EasyConnect 2.0 - 6.2.2
*/
static uint32_t *dpp_add_default_channels(struct dpp_sm *dpp, size_t *len_out)
{
struct wiphy *wiphy = wiphy_find_by_wdev(
netdev_get_wdev_id(dpp->netdev));
const struct scan_freq_set *list = wiphy_get_supported_freqs(wiphy);
uint32_t freq;
if (!dpp->presence_list)
dpp->presence_list = scan_freq_set_new();
scan_freq_set_add(dpp->presence_list, band_channel_to_freq(6,
BAND_FREQ_2_4_GHZ));
/*
* "5 GHz: Channel 44 (5.220 GHz) if local regulations permit operation
* only in the 5.150 - 5.250 GHz band and Channel 149 (5.745 GHz)
* otherwise"
*/
freq = band_channel_to_freq(149, BAND_FREQ_5_GHZ);
if (scan_freq_set_contains(list, freq))
scan_freq_set_add(dpp->presence_list, freq);
else
scan_freq_set_add(dpp->presence_list,
band_channel_to_freq(44, BAND_FREQ_5_GHZ));
/* TODO: 60GHz: Channel 2 */
return scan_freq_set_to_fixed_array(dpp->presence_list, len_out);
}
/*
* TODO: There is an entire procedure defined in the spec where you increase
* the ROC timeout with each unsuccessful iteration of channels, wait on channel
* for long periods of time etc. Due to offchannel issues in the kernel this
* procedure is not being fully implemented. In reality doing this would result
* in quite terrible DPP performance anyways.
*/
static void dpp_start_presence(struct dpp_sm *dpp, uint32_t *limit_freqs,
size_t limit_len)
{
uint32_t max_roc = wiphy_get_max_roc_duration(
wiphy_find_by_wdev(dpp->wdev_id));
if (2000 < max_roc)
max_roc = 2000;
if (limit_freqs) {
dpp->freqs = l_memdup(limit_freqs, sizeof(uint32_t) * limit_len);
dpp->freqs_len = limit_len;
} else
dpp->freqs = dpp_add_default_channels(dpp, &dpp->freqs_len);
dpp->dwell = max_roc;
dpp->freqs_idx = 0;
dpp->current_freq = dpp->freqs[0];
dpp->offchannel_id = offchannel_start(netdev_get_wdev_id(dpp->netdev),
dpp->current_freq, dpp->dwell, dpp_roc_started,
dpp, dpp_presence_timeout);
}
static struct l_dbus_message *dpp_dbus_start_enrollee(struct l_dbus *dbus,
struct l_dbus_message *message,
void *user_data)
@ -131,12 +356,24 @@ static struct l_dbus_message *dpp_dbus_start_enrollee(struct l_dbus *dbus,
uint32_t freq = band_channel_to_freq(6, BAND_FREQ_2_4_GHZ);
struct l_dbus_message *reply;
if (dpp->state != DPP_STATE_NOTHING)
return dbus_error_busy(message);
dpp->uri = dpp_generate_uri(dpp->pub_asn1, dpp->pub_asn1_len, 2,
netdev_get_address(dpp->netdev), &freq,
1, NULL, NULL);
dpp->state = DPP_STATE_PRESENCE;
l_debug("DPP Start Enrollee: %s", dpp->uri);
/*
* Going off spec here. Select a single channel to send presence
* announcements on. This will be advertised in the URI. The full
* presence procedure can be implemented if it is ever needed.
*/
dpp_start_presence(dpp, &freq, 1);
reply = l_dbus_message_new_method_return(message);
l_dbus_message_set_arguments(reply, "s", dpp->uri);
@ -172,6 +409,12 @@ static void dpp_destroy_interface(void *user_data)
static int dpp_init(void)
{
nl80211 = l_genl_family_new(iwd_get_genl(), NL80211_GENL_NAME);
if (!nl80211) {
l_error("Failed to obtain nl80211");
return -EIO;
}
netdev_watch = netdev_watch_add(dpp_netdev_watch, NULL, NULL);
l_dbus_register_interface(dbus_get_bus(), IWD_DPP_INTERFACE,