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mirror of https://git.kernel.org/pub/scm/network/wireless/iwd.git synced 2024-12-22 21:22:37 +01:00

dpp: add support for configuration protocol

This is a minimal implementation only supporting legacy network
configuration, i.e. only SSID and PSK/passphrase are supported.

Missing features include:
 - Fragmentation/comeback delay support
 - DPP AKM support
 - 8021x/PKEX support
This commit is contained in:
James Prestwood 2021-12-17 13:29:51 -08:00 committed by Denis Kenzior
parent 59a5cf3de4
commit 926c8bb9bd

334
src/dpp.c
View File

@ -44,6 +44,8 @@
#include "src/crypto.h" #include "src/crypto.h"
#include "src/mpdu.h" #include "src/mpdu.h"
#include "ell/useful.h" #include "ell/useful.h"
#include "src/common.h"
#include "src/storage.h"
static uint32_t netdev_watch; static uint32_t netdev_watch;
static struct l_genl_family *nl80211; static struct l_genl_family *nl80211;
@ -53,6 +55,7 @@ enum dpp_state {
DPP_STATE_NOTHING, DPP_STATE_NOTHING,
DPP_STATE_PRESENCE, DPP_STATE_PRESENCE,
DPP_STATE_AUTHENTICATING, DPP_STATE_AUTHENTICATING,
DPP_STATE_CONFIGURING,
}; };
struct dpp_sm { struct dpp_sm {
@ -84,6 +87,7 @@ struct dpp_sm {
uint8_t auth_addr[6]; uint8_t auth_addr[6];
uint8_t r_nonce[32]; uint8_t r_nonce[32];
uint8_t i_nonce[32]; uint8_t i_nonce[32];
uint8_t e_nonce[32];
uint64_t ke[L_ECC_MAX_DIGITS]; uint64_t ke[L_ECC_MAX_DIGITS];
uint64_t k2[L_ECC_MAX_DIGITS]; uint64_t k2[L_ECC_MAX_DIGITS];
@ -92,6 +96,8 @@ struct dpp_sm {
struct l_ecc_point *proto_public; struct l_ecc_point *proto_public;
struct l_ecc_point *i_proto_public; struct l_ecc_point *i_proto_public;
uint8_t diag_token;
}; };
static void dpp_free_auth_data(struct dpp_sm *dpp) static void dpp_free_auth_data(struct dpp_sm *dpp)
@ -203,6 +209,327 @@ static size_t dpp_build_header(const uint8_t *src, const uint8_t *dest,
return ptr - buf; return ptr - buf;
} }
static size_t dpp_build_config_header(const uint8_t *src, const uint8_t *dest,
uint8_t diag_token,
uint8_t buf[static 37])
{
uint8_t *ptr = buf + 24;
memset(buf, 0, 37);
l_put_le16(0x00d0, buf);
memcpy(buf + 4, dest, 6);
memcpy(buf + 10, src, 6);
memcpy(buf + 16, broadcast, 6);
*ptr++ = 0x04; /* Public */
*ptr++ = 0x0a; /* Action */
*ptr++ = diag_token;
*ptr++ = IE_TYPE_ADVERTISEMENT_PROTOCOL;
*ptr++ = 8; /* len */
*ptr++ = 0x00;
*ptr++ = IE_TYPE_VENDOR_SPECIFIC;
*ptr++ = 5;
memcpy(ptr, wifi_alliance_oui, 3);
ptr += 3;
*ptr++ = 0x1a;
*ptr++ = 1;
return ptr - buf;
}
/*
* The configuration protocols use of AD components is somewhat confusing
* since the request/response frames are of a different format than the rest.
* In addition there are situations where the components length is zero yet it
* is still passed as such to AES-SIV.
*
* For the configuration request/response frames:
*
* "AAD for use with AES-SIV for protected messages in the DPP Configuration
* protocol shall consist of all octets in the Query Request and Query Response
* fields up to the first octet of the Wrapped Data attribute, which is the last
* attribute in a DPP Configuration frame. When the number of octets of AAD is
* zero, the number of components of AAD passed to AES-SIV is zero."
*
* - For configuration requests the optional query request field is not
* included, therefore no AAD data is passed. (dpp_configuration_start)
*
* - The configuration response does contain a query response field which is
* 5 bytes. (dpp_handle_config_response_frame)
*
* For the configuration result/status, the same rules are used as the
* authentication protocol. This is reiterated in section 6.4.1.
*
* - For the configuration result there is some confusion as to exactly how the
* second AAD component should be passed (since the spec specifically
* mentions using two components). There are no attributes prior to the
* wrapped data component meaning the length would be zero.
* Hostapd/wpa_supplicant pass a zero length AAD component to AES-SIV which
* does effect the resulting encryption/decryption so this is also what IWD
* will do to remain compliant with it.
*/
static void dpp_configuration_start(struct dpp_sm *dpp, const uint8_t *addr)
{
const char *json = "{\"name\":\"IWD\",\"wi-fi_tech\":\"infra\","
"\"netRole\":\"sta\"}";
struct iovec iov[3];
uint8_t hdr[37];
uint8_t attrs[512];
size_t json_len = strlen(json);
uint8_t *ptr = attrs;
l_getrandom(&dpp->diag_token, 1);
iov[0].iov_len = dpp_build_config_header(
netdev_get_address(dpp->netdev),
addr, dpp->diag_token, hdr);
iov[0].iov_base = hdr;
l_getrandom(dpp->e_nonce, dpp->nonce_len);
/* length */
ptr += 2;
/*
* "AAD for use with AES-SIV for protected messages in the DPP
* Configuration protocol shall consist of all octets in the Query
* Request and Query Response fields up to the first octet of the
* Wrapped Data attribute"
*
* In this case there is no query request/response fields, nor any
* attributes besides wrapped data meaning zero AD components.
*/
ptr += dpp_append_wrapped_data(NULL, 0, NULL, 0, ptr, sizeof(attrs),
dpp->ke, dpp->key_len, 2,
DPP_ATTR_ENROLLEE_NONCE, dpp->nonce_len, dpp->e_nonce,
DPP_ATTR_CONFIGURATION_REQUEST, json_len, json);
l_put_le16(ptr - attrs - 2, attrs);
iov[1].iov_base = attrs;
iov[1].iov_len = ptr - attrs;
dpp->state = DPP_STATE_CONFIGURING;
dpp_send_frame(dpp->wdev_id, iov, 2, dpp->current_freq);
}
static void send_config_result(struct dpp_sm *dpp, const uint8_t *to)
{
uint8_t hdr[32];
struct iovec iov[2];
uint8_t attrs[256];
uint8_t *ptr = attrs;
uint8_t zero = 0;
iov[0].iov_len = dpp_build_header(netdev_get_address(dpp->netdev), to,
DPP_FRAME_CONFIGURATION_RESULT, hdr);
iov[0].iov_base = hdr;
ptr += dpp_append_wrapped_data(hdr + 26, 6, attrs, 0, ptr,
sizeof(attrs), dpp->ke, dpp->key_len, 2,
DPP_ATTR_STATUS, 1, &zero,
DPP_ATTR_ENROLLEE_NONCE, dpp->nonce_len, dpp->e_nonce);
iov[1].iov_base = attrs;
iov[1].iov_len = ptr - attrs;
dpp_send_frame(dpp->wdev_id, iov, 2, dpp->current_freq);
}
static void dpp_write_config(struct dpp_configuration *config)
{
_auto_(l_free) char *ssid = l_malloc(config->ssid_len + 1);
_auto_(l_settings_free) struct l_settings *settings = l_settings_new();
_auto_(l_free) char *path;
memcpy(ssid, config->ssid, config->ssid_len);
ssid[config->ssid_len] = '\0';
path = storage_get_network_file_path(SECURITY_PSK, ssid);
if (l_settings_load_from_file(settings, path)) {
/* Remove any existing Security keys */
l_settings_remove_group(settings, "Security");
}
if (config->passphrase)
l_settings_set_string(settings, "Security", "Passphrase",
config->passphrase);
else if (config->psk)
l_settings_set_string(settings, "Security", "PreSharedKey",
config->psk);
l_debug("Storing credential for '%s(%s)'", ssid,
security_to_str(SECURITY_PSK));
storage_network_sync(SECURITY_PSK, ssid, settings);
}
static void dpp_handle_config_response_frame(const struct mmpdu_header *frame,
const void *body, size_t body_len,
int rssi, void *user_data)
{
struct dpp_sm *dpp = user_data;
const uint8_t *ptr = body;
uint16_t status;
uint16_t fragmented; /* Fragmented/Comeback delay field */
uint8_t adv_protocol_element[] = { 0x6C, 0x08, 0x7F };
uint8_t adv_protocol_id[] = { 0xDD, 0x05, 0x50, 0x6F,
0x9A, 0x1A, 0x01 };
uint16_t query_len;
struct dpp_attr_iter iter;
enum dpp_attribute_type type;
size_t len;
const uint8_t *data;
const char *json = NULL;
size_t json_len = 0;
int dstatus = -1;
const uint8_t *wrapped = NULL;
const uint8_t *e_nonce = NULL;
size_t wrapped_len = 0;
_auto_(l_free) uint8_t *unwrapped = NULL;
struct dpp_configuration *config;
uint8_t ad0[] = { 0x00, 0x10, 0x01, 0x00, 0x05 };
if (dpp->state != DPP_STATE_CONFIGURING)
return;
/*
* Can a configuration request come from someone other than who you
* authenticated to?
*/
if (memcmp(dpp->auth_addr, frame->address_2, 6))
return;
if (body_len < 19)
return;
ptr += 2;
if (*ptr++ != dpp->diag_token)
return;
status = l_get_le16(ptr);
ptr += 2;
if (status != 0) {
l_debug("Bad configuration status %u", status);
return;
}
fragmented = l_get_le16(ptr);
ptr += 2;
/*
* TODO: handle 0x0001 (fragmented), as well as comeback delay.
*/
if (fragmented != 0) {
l_debug("Fragmented messages not currently supported");
return;
}
if (memcmp(ptr, adv_protocol_element, sizeof(adv_protocol_element))) {
l_debug("Invalid Advertisement protocol element");
return;
}
ptr += sizeof(adv_protocol_element);
if (memcmp(ptr, adv_protocol_id, sizeof(adv_protocol_id))) {
l_debug("Invalid Advertisement protocol ID");
return;
}
ptr += sizeof(adv_protocol_id);
query_len = l_get_le16(ptr);
ptr += 2;
if (query_len > body_len - 19)
return;
dpp_attr_iter_init(&iter, ptr, query_len);
while (dpp_attr_iter_next(&iter, &type, &len, &data)) {
switch (type) {
case DPP_ATTR_STATUS:
dstatus = l_get_u8(data);
break;
case DPP_ATTR_WRAPPED_DATA:
wrapped = data;
wrapped_len = len;
break;
default:
/*
* TODO: CSR Attribute
*/
break;
}
}
if (dstatus != DPP_STATUS_OK || !wrapped) {
l_debug("Bad status or missing attributes");
return;
}
unwrapped = dpp_unwrap_attr(ad0, sizeof(ad0), NULL, 0, dpp->ke,
dpp->key_len, wrapped, wrapped_len,
&wrapped_len);
if (!unwrapped) {
l_debug("Failed to unwrap");
return;
}
dpp_attr_iter_init(&iter, unwrapped, wrapped_len);
while (dpp_attr_iter_next(&iter, &type, &len, &data)) {
switch (type) {
case DPP_ATTR_ENROLLEE_NONCE:
if (len != dpp->nonce_len)
break;
if (memcmp(data, dpp->e_nonce, dpp->nonce_len))
break;
e_nonce = data;
break;
case DPP_ATTR_CONFIGURATION_OBJECT:
json = (const char *)data;
json_len = len;
break;
default:
break;
}
}
if (!json || !e_nonce) {
l_debug("No configuration object in response");
return;
}
config = dpp_parse_configuration_object(json, json_len);
if (!config) {
l_error("Configuration object did not parse");
return;
}
dpp_write_config(config);
/*
* TODO: Depending on the info included in the configuration object a
* limited scan could be issued to get autoconnect to trigger faster.
* In addition this network may already be in past scan results and
* could be joined immediately.
*
* For now just wait for autoconnect.
*/
dpp_configuration_free(config);
send_config_result(dpp, dpp->auth_addr);
}
/* /*
* The Authentication protocol has a consistent use of AD components, and this * The Authentication protocol has a consistent use of AD components, and this
* use is defined in 6.3.1.4: * use is defined in 6.3.1.4:
@ -407,6 +734,8 @@ static void authenticate_confirm(struct dpp_sm *dpp, const uint8_t *from,
l_debug("Authentication successful"); l_debug("Authentication successful");
dpp_configuration_start(dpp, from);
return; return;
auth_confirm_failed: auth_confirm_failed:
@ -693,6 +1022,7 @@ static void dpp_create(struct netdev *netdev)
struct l_dbus *dbus = dbus_get_bus(); struct l_dbus *dbus = dbus_get_bus();
struct dpp_sm *dpp = l_new(struct dpp_sm, 1); struct dpp_sm *dpp = l_new(struct dpp_sm, 1);
uint8_t dpp_prefix[] = { 0x04, 0x09, 0x50, 0x6f, 0x9a, 0x1a, 0x01 }; uint8_t dpp_prefix[] = { 0x04, 0x09, 0x50, 0x6f, 0x9a, 0x1a, 0x01 };
uint8_t dpp_conf_response_prefix[] = { 0x04, 0x0b };
dpp->netdev = netdev; dpp->netdev = netdev;
dpp->state = DPP_STATE_NOTHING; dpp->state = DPP_STATE_NOTHING;
@ -715,6 +1045,10 @@ static void dpp_create(struct netdev *netdev)
frame_watch_add(netdev_get_wdev_id(netdev), 0, 0x00d0, dpp_prefix, frame_watch_add(netdev_get_wdev_id(netdev), 0, 0x00d0, dpp_prefix,
sizeof(dpp_prefix), dpp_handle_auth_frame, sizeof(dpp_prefix), dpp_handle_auth_frame,
dpp, NULL); dpp, NULL);
frame_watch_add(netdev_get_wdev_id(netdev), 0, 0x00d0,
dpp_conf_response_prefix,
sizeof(dpp_conf_response_prefix),
dpp_handle_config_response_frame, dpp, NULL);
} }
static void dpp_netdev_watch(struct netdev *netdev, static void dpp_netdev_watch(struct netdev *netdev,