From 580581fd966015538b527fcd52449055b795cbf4 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Sun, 10 Oct 2021 01:09:25 +0200 Subject: conf: Avoid getifaddrs(), split L2/L3 address fetching, get filtered dumps getifaddrs() needs to allocate heap memory, and gets a ton of results we don't need. Use explicit netlink messages with "strict checking" instead. While at it, separate L2/L3 address handling, so that we don't fetch MAC addresses for IPv6, and also use netlink instead of ioctl() to get the MAC address. Signed-off-by: Stefano Brivio --- conf.c | 292 ++++++++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 169 insertions(+), 123 deletions(-) (limited to 'conf.c') diff --git a/conf.c b/conf.c index 3d07692..94ecf44 100644 --- a/conf.c +++ b/conf.c @@ -267,14 +267,27 @@ overlap: } /** - * struct nl_request - Netlink request filled and sent by get_routes() - * @nlh: Netlink message header - * @rtm: Routing Netlink message + * nl_req() - Send netlink request and read response, doesn't return on failure + * @buf: Buffer for response (BUFSIZ long) + * @req: Request with netlink header + * @len: Request length */ -struct nl_request { - struct nlmsghdr nlh; - struct rtmsg rtm; -}; +static void nl_req(char *buf, void *req, ssize_t len) +{ + int s = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE), v = 1; + struct sockaddr_nl addr = { .nl_family = AF_NETLINK, }; + + if (s < 0 || + setsockopt(s, SOL_NETLINK, NETLINK_GET_STRICT_CHK, &v, sizeof(v)) || + bind(s, (struct sockaddr *)&addr, sizeof(addr)) || + (send(s, req, len, 0) < len) || + (recv(s, buf, BUFSIZ, 0) < 0)) { + perror("netlink recv"); + exit(EXIT_FAILURE); + } + + close(s); +} /** * get_routes() - Get default route and fill in routable interface name @@ -282,57 +295,33 @@ struct nl_request { */ static void get_routes(struct ctx *c) { - struct nl_request req = { - .nlh.nlmsg_type = RTM_GETROUTE, + struct { struct nlmsghdr nlh; struct rtmsg rtm; } req = { + .nlh.nlmsg_type = RTM_GETROUTE, .nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP | NLM_F_EXCL, - .nlh.nlmsg_len = sizeof(struct nl_request), - .nlh.nlmsg_seq = 1, - .rtm.rtm_family = AF_INET, - .rtm.rtm_table = RT_TABLE_MAIN, - .rtm.rtm_scope = RT_SCOPE_UNIVERSE, - .rtm.rtm_type = RTN_UNICAST, + .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)), + .nlh.nlmsg_seq = 1, + .rtm.rtm_family = AF_INET, + .rtm.rtm_table = RT_TABLE_MAIN, + .rtm.rtm_scope = RT_SCOPE_UNIVERSE, + .rtm.rtm_type = RTN_UNICAST, }; - struct sockaddr_nl addr = { - .nl_family = AF_NETLINK, - }; - struct nlmsghdr *nlh; - int s, n, na, v4, v6; - char ifn[IFNAMSIZ]; + char ifn[IFNAMSIZ], buf[BUFSIZ]; + struct nlmsghdr *nh; struct rtattr *rta; struct rtmsg *rtm; - char buf[BUFSIZ]; + int n, na, v4, v6; if (!c->v4 && !c->v6) v4 = v6 = -1; else v6 = -!(v4 = -c->v4); - s = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); - if (s < 0) { - perror("netlink socket"); - goto out; - } - - if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) { - perror("netlink bind"); - goto out; - } - v6: - if (send(s, &req, sizeof(req), 0) < 0) { - perror("netlink send"); - goto out; - } - - n = recv(s, &buf, sizeof(buf), 0); - if (n < 0) { - perror("netlink recv"); - goto out; - } + nl_req(buf, &req, sizeof(req)); + nh = (struct nlmsghdr *)buf; - nlh = (struct nlmsghdr *)buf; - for ( ; NLMSG_OK(nlh, n); nlh = NLMSG_NEXT(nlh, n)) { - rtm = (struct rtmsg *)NLMSG_DATA(nlh); + for ( ; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) { + rtm = (struct rtmsg *)NLMSG_DATA(nh); if (rtm->rtm_dst_len || (rtm->rtm_family != AF_INET && rtm->rtm_family != AF_INET6)) @@ -342,7 +331,7 @@ v6: if (*c->ifn) { *ifn = 0; for (rta = (struct rtattr *)RTM_RTA(rtm), - na = RTM_PAYLOAD(nlh); + na = RTM_PAYLOAD(nh); RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { if (rta->rta_type != RTA_OIF) continue; @@ -355,7 +344,7 @@ v6: goto next; } - for (rta = (struct rtattr *)RTM_RTA(rtm), na = RTM_PAYLOAD(nlh); + for (rta = (struct rtattr *)RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { if (!*c->ifn && rta->rta_type == RTA_OIF) if_indextoname(*(unsigned *)RTA_DATA(rta), ifn); @@ -380,23 +369,18 @@ v6: } next: - if (nlh->nlmsg_type == NLMSG_DONE) + if (nh->nlmsg_type == NLMSG_DONE) break; } - if (v6 == -1) { + if (v6 < 0 && req.rtm.rtm_family == AF_INET) { req.rtm.rtm_family = AF_INET6; req.nlh.nlmsg_seq++; - recv(s, &buf, sizeof(buf), 0); - v6--; goto v6; } else if (v6 < 0) { v6 = 0; } -out: - close(s); - if ((v4 <= 0 && v6 <= 0) || (!*c->ifn && !*ifn)) { err("No routing information"); exit(EXIT_FAILURE); @@ -409,80 +393,98 @@ out: } /** - * get_addrs() - Fetch MAC, IP addresses, masks of external routable interface + * get_l3_addrs() - Fetch IP addresses of external routable interface * @c: Execution context */ -static void get_addrs(struct ctx *c) +static void get_l3_addrs(struct ctx *c) { - struct ifreq ifr = { - .ifr_addr.sa_family = AF_INET, + struct { struct nlmsghdr nlh; struct ifaddrmsg ifa; } req = { + .nlh.nlmsg_type = RTM_GETADDR, + .nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP, + .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)), + .nlh.nlmsg_seq = 1, + .ifa.ifa_family = AF_INET, + .ifa.ifa_index = if_nametoindex(c->ifn), }; - struct ifaddrs *ifaddr, *ifa; - int s, v4 = 0, v6 = 0; - - if (getifaddrs(&ifaddr) == -1) { - perror("getifaddrs"); - goto out; - } + struct ifaddrmsg *ifa; + struct nlmsghdr *nh; + struct rtattr *rta; + int n, na, v4, v6; + char buf[BUFSIZ]; - if (c->addr4) { - c->addr4_seen = c->addr4; - v4 = 1; + if (c->v4) { + v4 = -1; + if ((c->addr4_seen = c->addr4)) + v4 = 1; } - if (!IN6_IS_ADDR_UNSPECIFIED(&c->addr6)) { - memcpy(&c->addr6_seen, &c->addr6, sizeof(c->addr6)); - memcpy(&c->addr6_ll_seen, &c->addr6, sizeof(c->addr6)); - v6 = 1; + if (c->v6) { + v6 = -2; + if (!IN6_IS_ADDR_UNSPECIFIED(&c->addr6)) { + memcpy(&c->addr6_seen, &c->addr6, sizeof(c->addr6)); + memcpy(&c->addr6_ll_seen, &c->addr6, sizeof(c->addr6)); + v6 = -1; + } } - /* Fill in any missing information */ - for (ifa = ifaddr; ifa; ifa = ifa->ifa_next) { - struct sockaddr_in *in_addr; - struct sockaddr_in *in_mask; - struct sockaddr_in6 *in6_addr; +next_v: + if (v4 < 0) + req.ifa.ifa_family = AF_INET; + else if (v6 < 0) + req.ifa.ifa_family = AF_INET6; + else + goto mask_only; - if (strcmp(ifa->ifa_name, c->ifn)) - continue; + nl_req(buf, &req, sizeof(req)); + nh = (struct nlmsghdr *)buf; - if (!ifa->ifa_addr) - continue; + for ( ; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) { + if (nh->nlmsg_type != RTM_NEWADDR) + goto next; - in_addr = (struct sockaddr_in *)ifa->ifa_addr; - if (ifa->ifa_addr->sa_family == AF_INET && !c->addr4) { - c->addr4_seen = c->addr4 = in_addr->sin_addr.s_addr; - v4 = 1; - } + ifa = (struct ifaddrmsg *)NLMSG_DATA(nh); - if (ifa->ifa_addr->sa_family == AF_INET && !c->mask4 && - in_addr->sin_addr.s_addr == c->addr4) { - in_mask = (struct sockaddr_in *)ifa->ifa_netmask; - c->mask4 = in_mask->sin_addr.s_addr; - } + for (rta = (struct rtattr *)IFA_RTA(ifa), na = RTM_PAYLOAD(nh); + RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type != IFA_ADDRESS) + continue; - if (ifa->ifa_addr->sa_family == AF_INET6) { - in6_addr = (struct sockaddr_in6 *)ifa->ifa_addr; - if (IN6_IS_ADDR_LINKLOCAL(&in6_addr->sin6_addr) && - IN6_IS_ADDR_UNSPECIFIED(&c->addr6_ll)) { - memcpy(&c->addr6_ll, &in6_addr->sin6_addr, - sizeof(c->addr6_ll)); - } else if (IN6_IS_ADDR_UNSPECIFIED(&c->addr6)) { - memcpy(&c->addr6, &in6_addr->sin6_addr, - sizeof(c->addr6)); - memcpy(&c->addr6_seen, &in6_addr->sin6_addr, - sizeof(c->addr6_seen)); - memcpy(&c->addr6_ll_seen, &in6_addr->sin6_addr, - sizeof(c->addr6_seen)); - v6 = 1; + if (v4 < 0) { + memcpy(&c->addr4, RTA_DATA(rta), + sizeof(c->addr4)); + memcpy(&c->addr4_seen, RTA_DATA(rta), + sizeof(c->addr4_seen)); + v4 = 1; + } else if (v6 < 0) { + if (v6 == -2 && + ifa->ifa_scope == RT_SCOPE_UNIVERSE) { + memcpy(&c->addr6, RTA_DATA(rta), + sizeof(c->addr6)); + memcpy(&c->addr6_seen, RTA_DATA(rta), + sizeof(c->addr6_seen)); + memcpy(&c->addr6_ll_seen, RTA_DATA(rta), + sizeof(c->addr6_ll_seen)); + } else if (ifa->ifa_scope == RT_SCOPE_LINK) { + memcpy(&c->addr6_ll, RTA_DATA(rta), + sizeof(c->addr6_ll)); + } + if (!IN6_IS_ADDR_UNSPECIFIED(&c->addr6) && + !IN6_IS_ADDR_UNSPECIFIED(&c->addr6_ll)) + v6 = 1; } } +next: + if (nh->nlmsg_type == NLMSG_DONE) + break; } - freeifaddrs(ifaddr); + if (v4 >= 0 && v6 < 0) + goto next_v; if (v4 < c->v4 || v6 < c->v6) goto out; +mask_only: if (v4 && !c->mask4) { if (IN_CLASSA(ntohl(c->addr4))) c->mask4 = htonl(IN_CLASSA_NET); @@ -494,28 +496,68 @@ static void get_addrs(struct ctx *c) c->mask4 = 0xffffffff; } - if (!memcmp(c->mac, ((uint8_t [ETH_ALEN]){ 0 }), ETH_ALEN)) { - s = socket(AF_INET, SOCK_DGRAM, 0); - if (s < 0) { - perror("socket SIOCGIFHWADDR"); - goto out; - } + return; +out: + err("Couldn't get addresses for routable interface"); + exit(EXIT_FAILURE); +} - strncpy(ifr.ifr_name, c->ifn, IF_NAMESIZE); - if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0) { - perror("SIOCGIFHWADDR"); - goto out; - } +/** + * get_l2_addr() - Fetch hardware addresses of external routable interface + * @c: Execution context + */ +static void get_l2_addr(struct ctx *c) +{ + struct { struct nlmsghdr nlh; struct ifinfomsg ifi; } req = { + .nlh.nlmsg_type = RTM_GETLINK, + .nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP_FILTERED, + .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)), + .nlh.nlmsg_seq = 1, + .ifi.ifi_family = AF_UNSPEC, + .ifi.ifi_index = if_nametoindex(c->ifn), + }; + struct ifinfomsg *ifi; + struct nlmsghdr *nh; + struct rtattr *rta; + char buf[BUFSIZ]; + int n, na; + + if (memcmp(c->mac, ((uint8_t [ETH_ALEN]){ 0 }), ETH_ALEN)) + goto mac_guest; - close(s); - memcpy(c->mac, ifr.ifr_hwaddr.sa_data, ETH_ALEN); + nl_req(buf, &req, sizeof(req)); + nh = (struct nlmsghdr *)buf; + + for ( ; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) { + if (nh->nlmsg_type != RTM_NEWLINK) + goto next; + + ifi = (struct ifinfomsg *)NLMSG_DATA(nh); + + for (rta = (struct rtattr *)IFLA_RTA(ifi), na = RTM_PAYLOAD(nh); + RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type != IFLA_ADDRESS) + continue; + + memcpy(c->mac, RTA_DATA(rta), ETH_ALEN); + break; + } +next: + if (nh->nlmsg_type == NLMSG_DONE) + break; } - memset(&c->mac_guest, 0xff, sizeof(c->mac_guest)); + if (!memcmp(c->mac, ((uint8_t [ETH_ALEN]){ 0 }), ETH_ALEN)) + goto out; + +mac_guest: + if (memcmp(c->mac_guest, ((uint8_t [ETH_ALEN]){ 0 }), ETH_ALEN)) + memset(&c->mac_guest, 0xff, sizeof(c->mac_guest)); return; + out: - err("Couldn't get addresses for routable interface"); + err("Couldn't get hardware address for routable interface"); exit(EXIT_FAILURE); } @@ -888,6 +930,8 @@ void conf_print(struct ctx *c) inet_ntop(AF_INET6, &c->addr6, buf6, sizeof(buf6))); info(" router: %s", inet_ntop(AF_INET6, &c->gw6, buf6, sizeof(buf6))); + info(" our link-local: %s", + inet_ntop(AF_INET6, &c->addr6_ll, buf6, sizeof(buf6))); for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->dns6[i]); i++) { if (!i) @@ -1290,7 +1334,9 @@ void conf(struct ctx *c, int argc, char **argv) } get_routes(c); - get_addrs(c); + get_l3_addrs(c); + if (c->v4) + get_l2_addr(c); if (c->mode == MODE_PASTA && dns4 == c->dns4 && dns6 == c->dns6) c->no_dns = 1; -- cgit v1.2.3