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[50.78.19.50]) by smtp.gmail.com with ESMTPSA id c10-20020a05621401ea00b0065b11053445sm2958163qvu.54.2023.11.10.06.16.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Nov 2023 06:16:23 -0800 (PST) From: James Prestwood To: iwd@lists.linux.dev Cc: James Prestwood Subject: [PATCH v2 1/3] dpp: scan to pick up extra frequencies when enrolling Date: Fri, 10 Nov 2023 06:16:18 -0800 Message-Id: <20231110141620.80195-1-prestwoj@gmail.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: iwd@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The DPP-PKEX spec provides a very limited list of frequencies used to discover configurators, only 3 on 2.4 and 5GHz bands. Since configurators (at least in IWD's implementation) are only allowed on the current operating frequency its very unlikely an enrollee will find a configurator on these frequencies out of the entire spectrum. The spec does mention that the 3 default frequencies should be used "In lieu of specific channel information obtained in a manner outside the scope of this specification, ...". This allows the implementation some flexibility in using a broader range of frequencies. To increase the chances of finding a configurator shared code enrollees will first issue a scan to determine what access points are around, then iterate these frequencies. This is especially helpful when the configurators are IWD-based since we know that they'll be on the same channels as the APs in the area. --- src/dpp.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 88 insertions(+), 10 deletions(-) v2: * Removed user-option, scan by default * Fixed potential NULL return from dpp_default_freqs diff --git a/src/dpp.c b/src/dpp.c index c54bd484..daa49410 100644 --- a/src/dpp.c +++ b/src/dpp.c @@ -182,6 +182,7 @@ struct dpp_sm { size_t z_len; uint8_t u[L_ECC_SCALAR_MAX_BYTES]; size_t u_len; + uint32_t pkex_scan_id; bool mcast_support : 1; bool roc_started : 1; @@ -507,6 +508,11 @@ static void dpp_reset(struct dpp_sm *dpp) dpp->retry_timeout = NULL; } + if (dpp->pkex_scan_id) { + scan_cancel(dpp->wdev_id, dpp->pkex_scan_id); + dpp->pkex_scan_id = 0; + } + dpp->state = DPP_STATE_NOTHING; dpp->new_freq = 0; dpp->frame_retry = 0; @@ -3956,6 +3962,14 @@ static struct l_dbus_message *dpp_dbus_stop(struct l_dbus *dbus, return l_dbus_message_new_method_return(message); } +static void dpp_pkex_scan_trigger(int err, void *user_data) +{ + struct dpp_sm *dpp = user_data; + + if (err < 0) + dpp_reset(dpp); +} + /* * Section 5.6.1 * In lieu of specific channel information obtained in a manner outside @@ -3994,6 +4008,62 @@ static uint32_t *dpp_default_freqs(struct dpp_sm *dpp, size_t *out_len) return freqs_out; } +static bool dpp_pkex_scan_notify(int err, struct l_queue *bss_list, + const struct scan_freq_set *freqs, + void *user_data) +{ + struct dpp_sm *dpp = user_data; + const struct l_queue_entry *e; + _auto_(scan_freq_set_free) struct scan_freq_set *freq_set = NULL; + + if (err < 0) + goto failed; + + freq_set = scan_freq_set_new(); + + if (!bss_list || l_queue_isempty(bss_list)) { + dpp->freqs = dpp_default_freqs(dpp, &dpp->freqs_len); + if (!dpp->freqs) + goto failed; + + l_debug("No BSS's seen, using default frequency list"); + goto start; + } + + for (e = l_queue_get_entries(bss_list); e; e = e->next) { + const struct scan_bss *bss = e->data; + + scan_freq_set_add(freq_set, bss->frequency); + } + + l_debug("Found %u frequencies to search for configurator", + l_queue_length(bss_list)); + + dpp->freqs = scan_freq_set_to_fixed_array(freq_set, &dpp->freqs_len); + +start: + dpp->current_freq = dpp->freqs[0]; + + dpp_reset_protocol_timer(dpp, DPP_PKEX_PROTO_TIMEOUT); + + l_debug("PKEX start enrollee (id=%s)", dpp->pkex_id ?: "unset"); + + dpp_start_offchannel(dpp, dpp->current_freq); + + return false; + +failed: + dpp_reset(dpp); + return false; +} + +static void dpp_pkex_scan_destroy(void *user_data) +{ + struct dpp_sm *dpp = user_data; + + dpp->pkex_scan_id = 0; +} + static bool dpp_start_pkex_enrollee(struct dpp_sm *dpp, const char *key, const char *identifier) { @@ -4045,17 +4115,25 @@ static bool dpp_start_pkex_enrollee(struct dpp_sm *dpp, const char *key, dpp_property_changed_notify(dpp); - dpp->freqs = dpp_default_freqs(dpp, &dpp->freqs_len); - if (!dpp->freqs) - goto failed; - - dpp->current_freq = dpp->freqs[dpp->freqs_idx]; - - dpp_reset_protocol_timer(dpp, DPP_PKEX_PROTO_TIMEOUT); - - l_debug("PKEX start enrollee (id=%s)", dpp->pkex_id ?: "unset"); + /* + * The 'dpp_default_freqs' function returns the default frequencies + * outlined in section 5.6.1. For 2.4/5GHz this is only 3 frequencies + * which is unlikely to result in discovery of a configurator. The spec + * does allow frequencies to be "obtained in a manner outside the scope + * of this specification" which is what is being done here. + * + * This is mainly geared towards IWD-based configurators; banking on the + * fact that they are currently connected to nearby APs. Scanning lets + * us see nearby BSS's which should be the same frequencies as our + * target configurator. + */ + l_debug("Performing scan for frequencies to start PKEX"); - dpp_start_offchannel(dpp, dpp->current_freq); + dpp->pkex_scan_id = scan_active(dpp->wdev_id, NULL, 0, + dpp_pkex_scan_trigger, dpp_pkex_scan_notify, + dpp, dpp_pkex_scan_destroy); + if (!dpp->pkex_scan_id) + goto failed; return true;