X-Git-Url: https://git.decadent.org.uk/gitweb/?p=odhcp6c.git;a=blobdiff_plain;f=src%2Fdhcpv6.c;h=86f24e070bf9d5c6d4ecc66a4e2c1c12380c3d71;hp=846df9d2285ab49857117bb47bfc6d2ce3ec1042;hb=3fb3c327d889a8c5e0370259c4c6360c7d3106cb;hpb=a300c7335c5ad78fb053e7c73b45e95e1f3c2ad1 diff --git a/src/dhcpv6.c b/src/dhcpv6.c index 846df9d..86f24e0 100644 --- a/src/dhcpv6.c +++ b/src/dhcpv6.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -31,6 +32,7 @@ #include #include "odhcp6c.h" +#include "md5.h" #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\ @@ -83,6 +85,9 @@ static int request_prefix = -1; static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE; static bool accept_reconfig = false; +// Reconfigure key +static uint8_t reconf_key[16]; + int init_dhcpv6(const char *ifname, int request_pd) @@ -135,7 +140,8 @@ int init_dhcpv6(const char *ifname, int request_pd) htons(DHCPV6_OPT_DNS_DOMAIN), htons(DHCPV6_OPT_NTP_SERVER), htons(DHCPV6_OPT_SIP_SERVER_A), - htons(DHCPV6_OPT_SIP_SERVER_D)}; + htons(DHCPV6_OPT_SIP_SERVER_D), + htons(DHCPV6_OPT_PD_EXCLUDE)}; odhcp6c_add_state(STATE_ORO, oro, sizeof(oro)); @@ -188,7 +194,6 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs) // Build IA_PDs size_t ia_pd_entries, ia_pd_len = 0; - void *ia_pd = NULL; struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries); ia_pd_entries /= sizeof(*e); struct dhcpv6_ia_hdr hdr_ia_pd = { @@ -197,32 +202,51 @@ static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs) 1, 0, 0 }; - struct dhcpv6_ia_prefix pref = { - .type = htons(DHCPV6_OPT_IA_PREFIX), - .len = htons(25), .prefix = request_prefix - }; - - struct dhcpv6_ia_prefix p[ia_pd_entries]; + uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10)); for (size_t i = 0; i < ia_pd_entries; ++i) { - p[i].type = htons(DHCPV6_OPT_IA_PREFIX); - p[i].len = htons(sizeof(p[i]) - 4U); - p[i].preferred = 0; - p[i].valid = 0; - p[i].prefix = e[i].length; - p[i].addr = e[i].target; + uint8_t ex_len = 0; + if (e[i].priority > 0) + ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6; + + struct dhcpv6_ia_prefix p = { + .type = htons(DHCPV6_OPT_IA_PREFIX), + .len = htons(sizeof(p) - 4U + ex_len), + .prefix = e[i].length, + .addr = e[i].target + }; + + memcpy(ia_pd + ia_pd_len, &p, sizeof(p)); + ia_pd_len += sizeof(p); + + if (ex_len) { + ia_pd[ia_pd_len++] = 0; + ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE; + ia_pd[ia_pd_len++] = 0; + ia_pd[ia_pd_len++] = ex_len - 4; + ia_pd[ia_pd_len++] = e[i].priority; + + uint32_t excl = ntohl(e[i].router.s6_addr32[1]); + excl >>= (64 - e[i].priority); + excl <<= 8 - ((e[i].priority - e[i].length) % 8); + + for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8) + ia_pd[ia_pd_len + i] = excl & 0xff; + ia_pd_len += ex_len - 5; + } } - ia_pd = p; - ia_pd_len = sizeof(p); - hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len); - if (request_prefix > 0 && + struct dhcpv6_ia_prefix pref = { + .type = htons(DHCPV6_OPT_IA_PREFIX), + .len = htons(25), .prefix = request_prefix + }; + if (request_prefix > 0 && ia_pd_len == 0 && (type == DHCPV6_MSG_SOLICIT || type == DHCPV6_MSG_REQUEST)) { - ia_pd = &pref; + ia_pd = (uint8_t*)&pref; ia_pd_len = sizeof(pref); - hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len); } + hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len); // Build IA_NAs size_t ia_na_entries, ia_na_len = 0; @@ -450,19 +474,55 @@ static bool dhcpv6_response_is_valid(const void *buf, ssize_t len, uint8_t *end = ((uint8_t*)buf) + len, *odata; uint16_t otype, olen; - bool clientid_ok = false, serverid_ok = false; + bool clientid_ok = false, serverid_ok = false, rcauth_ok = false; size_t client_id_len, server_id_len; void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len); void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len); - dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) - if (otype == DHCPV6_OPT_CLIENTID) + dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) { + if (otype == DHCPV6_OPT_CLIENTID) { clientid_ok = (olen + 4U == client_id_len) && !memcmp( &odata[-4], client_id, client_id_len); - else if (otype == DHCPV6_OPT_SERVERID) + } else if (otype == DHCPV6_OPT_SERVERID) { serverid_ok = (olen + 4U == server_id_len) && !memcmp( &odata[-4], server_id, server_id_len); + } else if (otype == DHCPV6_OPT_AUTH && olen == -4 + + sizeof(struct dhcpv6_auth_reconfigure)) { + struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4]; + if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2) + continue; + + md5_state_t md5; + uint8_t serverhash[16], secretbytes[16], hash[16]; + memcpy(serverhash, r->key, sizeof(serverhash)); + memset(r->key, 0, sizeof(r->key)); + memcpy(secretbytes, reconf_key, sizeof(secretbytes)); + + for (size_t i = 0; i < sizeof(secretbytes); ++i) + secretbytes[i] ^= 0x36; + + md5_init(&md5); + md5_append(&md5, secretbytes, sizeof(secretbytes)); + md5_append(&md5, buf, len); + md5_finish(&md5, hash); + + for (size_t i = 0; i < sizeof(secretbytes); ++i) { + secretbytes[i] ^= 0x36; + secretbytes[i] ^= 0x5c; + } + + md5_init(&md5); + md5_append(&md5, secretbytes, sizeof(secretbytes)); + md5_append(&md5, hash, 16); + md5_finish(&md5, hash); + + rcauth_ok = !memcmp(hash, serverhash, sizeof(hash)); + } + } + + if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok) + return false; return clientid_ok && (serverid_ok || server_id_len == 0); } @@ -712,6 +772,12 @@ static int dhcpv6_handle_reply(enum dhcpv6_msg orig, uint32_t refresh = ntohl(*((uint32_t*)odata)); if (refresh < (uint32_t)t1) t1 = refresh; + } else if (otype == DHCPV6_OPT_AUTH && olen == -4 + + sizeof(struct dhcpv6_auth_reconfigure)) { + struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4]; + if (r->protocol == 3 && r->algorithm == 1 && + r->reconf_type == 1) + memcpy(reconf_key, r->key, sizeof(r->key)); } else if (otype != DHCPV6_OPT_CLIENTID && otype != DHCPV6_OPT_SERVERID) { odhcp6c_add_state(STATE_CUSTOM_OPTS, @@ -748,7 +814,50 @@ static uint32_t dhcpv6_parse_ia(void *opt, void *end) entry.length = prefix->prefix; entry.target = prefix->addr; - odhcp6c_update_entry(STATE_IA_PD, &entry); + // Parse PD-exclude + bool ok = true; + uint16_t stype, slen; + uint8_t *sdata; + dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U, + odata + olen, stype, slen, sdata) { + if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2) + continue; + + uint8_t elen = sdata[0]; + if (elen > 64) + elen = 64; + + if (elen <= 32 || elen <= entry.length) { + ok = false; + continue; + } + + + uint8_t bytes = ((elen - entry.length - 1) / 8) + 1; + if (slen <= bytes) { + ok = false; + continue; + } + + uint32_t exclude = 0; + do { + exclude = exclude << 8 | sdata[bytes]; + } while (--bytes); + + exclude >>= 8 - ((elen - entry.length) % 8); + exclude <<= 64 - elen; + + // Abusing router & priority fields for exclusion + entry.router = entry.target; + entry.router.s6_addr32[1] |= htonl(exclude); + entry.priority = elen; + } + + if (ok) + odhcp6c_update_entry(STATE_IA_PD, &entry); + + entry.priority = 0; + memset(&entry.router, 0, sizeof(entry.router)); } else if (otype == DHCPV6_OPT_IA_ADDR) { struct dhcpv6_ia_addr *addr = (void*)&odata[-4]; if (olen + 4U < sizeof(*addr))