| /* |
| * Copyright (C) 2008 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #define LOG_TAG "NetlinkEvent" |
| |
| #include <arpa/inet.h> |
| #include <limits.h> |
| #include <linux/genetlink.h> |
| #include <linux/if.h> |
| #include <linux/if_addr.h> |
| #include <linux/if_link.h> |
| #include <linux/netfilter/nfnetlink.h> |
| #include <linux/netfilter/nfnetlink_log.h> |
| #include <linux/netlink.h> |
| #include <linux/rtnetlink.h> |
| #include <net/if.h> |
| #include <netinet/icmp6.h> |
| #include <netinet/in.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/personality.h> |
| #include <sys/socket.h> |
| #include <sys/types.h> |
| #include <sys/utsname.h> |
| |
| #include <android-base/parseint.h> |
| #include <bpf/KernelUtils.h> |
| #include <log/log.h> |
| #include <sysutils/NetlinkEvent.h> |
| |
| using android::base::ParseInt; |
| using android::bpf::isKernel64Bit; |
| |
| /* From kernel's net/netfilter/xt_quota2.c */ |
| const int LOCAL_QLOG_NL_EVENT = 112; |
| const int LOCAL_NFLOG_PACKET = NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET; |
| |
| /****************************************************************************** |
| * WARNING: HERE BE DRAGONS! * |
| * * |
| * This is here to provide for compatibility with both 32 and 64-bit kernels * |
| * from 32-bit userspace. * |
| * * |
| * The kernel definition of this struct uses types (like long) that are not * |
| * the same across 32-bit and 64-bit builds, and there is no compatibility * |
| * layer to fix it up before it reaches userspace. * |
| * As such we need to detect the bit-ness of the kernel and deal with it. * |
| * * |
| ******************************************************************************/ |
| |
| /* |
| * This is the verbatim kernel declaration from net/netfilter/xt_quota2.c, |
| * it is *NOT* of a well defined layout and is included here for compile |
| * time assertions only. |
| * |
| * It got there from deprecated ipt_ULOG.h to parse QLOG_NL_EVENT. |
| */ |
| #define ULOG_MAC_LEN 80 |
| #define ULOG_PREFIX_LEN 32 |
| typedef struct ulog_packet_msg { |
| unsigned long mark; |
| long timestamp_sec; |
| long timestamp_usec; |
| unsigned int hook; |
| char indev_name[IFNAMSIZ]; |
| char outdev_name[IFNAMSIZ]; |
| size_t data_len; |
| char prefix[ULOG_PREFIX_LEN]; |
| unsigned char mac_len; |
| unsigned char mac[ULOG_MAC_LEN]; |
| unsigned char payload[0]; |
| } ulog_packet_msg_t; |
| |
| // On Linux int is always 32 bits, while sizeof(long) == sizeof(void*), |
| // thus long on a 32-bit Linux kernel is 32-bits, like int always is |
| typedef int long32; |
| typedef unsigned int ulong32; |
| static_assert(sizeof(long32) == 4); |
| static_assert(sizeof(ulong32) == 4); |
| |
| // Here's the same structure definition with the assumption the kernel |
| // is compiled for 32-bits. |
| typedef struct { |
| ulong32 mark; |
| long32 timestamp_sec; |
| long32 timestamp_usec; |
| unsigned int hook; |
| char indev_name[IFNAMSIZ]; |
| char outdev_name[IFNAMSIZ]; |
| ulong32 data_len; |
| char prefix[ULOG_PREFIX_LEN]; |
| unsigned char mac_len; |
| unsigned char mac[ULOG_MAC_LEN]; |
| unsigned char payload[0]; |
| } ulog_packet_msg32_t; |
| |
| // long on a 64-bit kernel is 64-bits with 64-bit alignment, |
| // while long long is 64-bit but may have 32-bit aligment. |
| typedef long long __attribute__((__aligned__(8))) long64; |
| typedef unsigned long long __attribute__((__aligned__(8))) ulong64; |
| static_assert(sizeof(long64) == 8); |
| static_assert(sizeof(ulong64) == 8); |
| |
| // Here's the same structure definition with the assumption the kernel |
| // is compiled for 64-bits. |
| typedef struct { |
| ulong64 mark; |
| long64 timestamp_sec; |
| long64 timestamp_usec; |
| unsigned int hook; |
| char indev_name[IFNAMSIZ]; |
| char outdev_name[IFNAMSIZ]; |
| ulong64 data_len; |
| char prefix[ULOG_PREFIX_LEN]; |
| unsigned char mac_len; |
| unsigned char mac[ULOG_MAC_LEN]; |
| unsigned char payload[0]; |
| } ulog_packet_msg64_t; |
| |
| // One expects the 32-bit version to be smaller than the 64-bit version. |
| static_assert(sizeof(ulog_packet_msg32_t) < sizeof(ulog_packet_msg64_t)); |
| // And either way the 'native' version should match either the 32 or 64 bit one. |
| static_assert(sizeof(ulog_packet_msg_t) == sizeof(ulog_packet_msg32_t) || |
| sizeof(ulog_packet_msg_t) == sizeof(ulog_packet_msg64_t)); |
| |
| // In practice these sizes are always simply (for both x86 and arm): |
| static_assert(sizeof(ulog_packet_msg32_t) == 168); |
| static_assert(sizeof(ulog_packet_msg64_t) == 192); |
| |
| /******************************************************************************/ |
| |
| NetlinkEvent::NetlinkEvent() { |
| mAction = Action::kUnknown; |
| memset(mParams, 0, sizeof(mParams)); |
| mPath = nullptr; |
| mSubsystem = nullptr; |
| } |
| |
| NetlinkEvent::~NetlinkEvent() { |
| free(mPath); |
| free(mSubsystem); |
| for (auto param : mParams) { |
| free(param); |
| } |
| } |
| |
| void NetlinkEvent::dump() { |
| int i; |
| |
| for (i = 0; i < NL_PARAMS_MAX; i++) { |
| if (!mParams[i]) |
| break; |
| SLOGD("NL param '%s'\n", mParams[i]); |
| } |
| } |
| |
| /* |
| * Returns the message name for a message in the NETLINK_ROUTE family, or NULL |
| * if parsing that message is not supported. |
| */ |
| static const char *rtMessageName(int type) { |
| #define NL_EVENT_RTM_NAME(rtm) case rtm: return #rtm; |
| switch (type) { |
| NL_EVENT_RTM_NAME(RTM_NEWLINK); |
| NL_EVENT_RTM_NAME(RTM_DELLINK); |
| NL_EVENT_RTM_NAME(RTM_NEWADDR); |
| NL_EVENT_RTM_NAME(RTM_DELADDR); |
| NL_EVENT_RTM_NAME(RTM_NEWROUTE); |
| NL_EVENT_RTM_NAME(RTM_DELROUTE); |
| NL_EVENT_RTM_NAME(RTM_NEWNDUSEROPT); |
| NL_EVENT_RTM_NAME(LOCAL_QLOG_NL_EVENT); |
| NL_EVENT_RTM_NAME(LOCAL_NFLOG_PACKET); |
| default: |
| return nullptr; |
| } |
| #undef NL_EVENT_RTM_NAME |
| } |
| |
| /* |
| * Checks that a binary NETLINK_ROUTE message is long enough for a payload of |
| * size bytes. |
| */ |
| static bool checkRtNetlinkLength(const struct nlmsghdr *nh, size_t size) { |
| if (nh->nlmsg_len < NLMSG_LENGTH(size)) { |
| SLOGE("Got a short %s message\n", rtMessageName(nh->nlmsg_type)); |
| return false; |
| } |
| return true; |
| } |
| |
| /* |
| * Utility function to log errors. |
| */ |
| static bool maybeLogDuplicateAttribute(bool isDup, |
| const char *attributeName, |
| const char *messageName) { |
| if (isDup) { |
| SLOGE("Multiple %s attributes in %s, ignoring\n", attributeName, messageName); |
| return true; |
| } |
| return false; |
| } |
| |
| /* |
| * Parse a RTM_NEWLINK message. |
| */ |
| bool NetlinkEvent::parseIfInfoMessage(const struct nlmsghdr *nh) { |
| struct ifinfomsg *ifi = (struct ifinfomsg *) NLMSG_DATA(nh); |
| if (!checkRtNetlinkLength(nh, sizeof(*ifi))) |
| return false; |
| |
| if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) { |
| return false; |
| } |
| |
| int len = IFLA_PAYLOAD(nh); |
| struct rtattr *rta; |
| for (rta = IFLA_RTA(ifi); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) { |
| switch(rta->rta_type) { |
| case IFLA_IFNAME: |
| asprintf(&mParams[0], "INTERFACE=%s", (char *) RTA_DATA(rta)); |
| // We can get the interface change information from sysfs update |
| // already. But in case we missed those message when devices start. |
| // We do a update again when received a kLinkUp event. To make |
| // the message consistent, use IFINDEX here as well since sysfs |
| // uses IFINDEX. |
| asprintf(&mParams[1], "IFINDEX=%d", ifi->ifi_index); |
| mAction = (ifi->ifi_flags & IFF_LOWER_UP) ? Action::kLinkUp : |
| Action::kLinkDown; |
| mSubsystem = strdup("net"); |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| /* |
| * Parse a RTM_NEWADDR or RTM_DELADDR message. |
| */ |
| bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) { |
| struct ifaddrmsg *ifaddr = (struct ifaddrmsg *) NLMSG_DATA(nh); |
| struct ifa_cacheinfo *cacheinfo = nullptr; |
| char addrstr[INET6_ADDRSTRLEN] = ""; |
| char ifname[IFNAMSIZ] = ""; |
| uint32_t flags; |
| |
| if (!checkRtNetlinkLength(nh, sizeof(*ifaddr))) |
| return false; |
| |
| int type = nh->nlmsg_type; |
| if (type != RTM_NEWADDR && type != RTM_DELADDR) { |
| SLOGE("parseIfAddrMessage on incorrect message type 0x%x\n", type); |
| return false; |
| } |
| |
| // For log messages. |
| const char *msgtype = rtMessageName(type); |
| |
| // First 8 bits of flags. In practice will always be overridden when parsing IFA_FLAGS below. |
| flags = ifaddr->ifa_flags; |
| |
| struct rtattr *rta; |
| int len = IFA_PAYLOAD(nh); |
| for (rta = IFA_RTA(ifaddr); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) { |
| if (rta->rta_type == IFA_ADDRESS) { |
| // Only look at the first address, because we only support notifying |
| // one change at a time. |
| if (maybeLogDuplicateAttribute(*addrstr != '\0', "IFA_ADDRESS", msgtype)) |
| continue; |
| |
| // Convert the IP address to a string. |
| if (ifaddr->ifa_family == AF_INET) { |
| struct in_addr *addr4 = (struct in_addr *) RTA_DATA(rta); |
| if (RTA_PAYLOAD(rta) < sizeof(*addr4)) { |
| SLOGE("Short IPv4 address (%zu bytes) in %s", |
| RTA_PAYLOAD(rta), msgtype); |
| continue; |
| } |
| inet_ntop(AF_INET, addr4, addrstr, sizeof(addrstr)); |
| } else if (ifaddr->ifa_family == AF_INET6) { |
| struct in6_addr *addr6 = (struct in6_addr *) RTA_DATA(rta); |
| if (RTA_PAYLOAD(rta) < sizeof(*addr6)) { |
| SLOGE("Short IPv6 address (%zu bytes) in %s", |
| RTA_PAYLOAD(rta), msgtype); |
| continue; |
| } |
| inet_ntop(AF_INET6, addr6, addrstr, sizeof(addrstr)); |
| } else { |
| SLOGE("Unknown address family %d\n", ifaddr->ifa_family); |
| continue; |
| } |
| |
| // Find the interface name. |
| if (!if_indextoname(ifaddr->ifa_index, ifname)) { |
| SLOGD("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype); |
| } |
| |
| } else if (rta->rta_type == IFA_CACHEINFO) { |
| // Address lifetime information. |
| if (maybeLogDuplicateAttribute(cacheinfo, "IFA_CACHEINFO", msgtype)) |
| continue; |
| |
| if (RTA_PAYLOAD(rta) < sizeof(*cacheinfo)) { |
| SLOGE("Short IFA_CACHEINFO (%zu vs. %zu bytes) in %s", |
| RTA_PAYLOAD(rta), sizeof(cacheinfo), msgtype); |
| continue; |
| } |
| |
| cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta); |
| |
| } else if (rta->rta_type == IFA_FLAGS) { |
| flags = *(uint32_t*)RTA_DATA(rta); |
| } |
| } |
| |
| if (addrstr[0] == '\0') { |
| SLOGE("No IFA_ADDRESS in %s\n", msgtype); |
| return false; |
| } |
| |
| // Fill in netlink event information. |
| mAction = (type == RTM_NEWADDR) ? Action::kAddressUpdated : |
| Action::kAddressRemoved; |
| mSubsystem = strdup("net"); |
| asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr, ifaddr->ifa_prefixlen); |
| asprintf(&mParams[1], "INTERFACE=%s", ifname); |
| asprintf(&mParams[2], "FLAGS=%u", flags); |
| asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope); |
| asprintf(&mParams[4], "IFINDEX=%u", ifaddr->ifa_index); |
| |
| if (cacheinfo) { |
| asprintf(&mParams[5], "PREFERRED=%u", cacheinfo->ifa_prefered); |
| asprintf(&mParams[6], "VALID=%u", cacheinfo->ifa_valid); |
| asprintf(&mParams[7], "CSTAMP=%u", cacheinfo->cstamp); |
| asprintf(&mParams[8], "TSTAMP=%u", cacheinfo->tstamp); |
| } |
| |
| return true; |
| } |
| |
| /* |
| * Parse a QLOG_NL_EVENT message. |
| */ |
| bool NetlinkEvent::parseUlogPacketMessage(const struct nlmsghdr *nh) { |
| const char* alert; |
| const char* devname; |
| |
| if (isKernel64Bit()) { |
| ulog_packet_msg64_t* pm64 = (ulog_packet_msg64_t*)NLMSG_DATA(nh); |
| if (!checkRtNetlinkLength(nh, sizeof(*pm64))) return false; |
| alert = pm64->prefix; |
| devname = pm64->indev_name[0] ? pm64->indev_name : pm64->outdev_name; |
| } else { |
| ulog_packet_msg32_t* pm32 = (ulog_packet_msg32_t*)NLMSG_DATA(nh); |
| if (!checkRtNetlinkLength(nh, sizeof(*pm32))) return false; |
| alert = pm32->prefix; |
| devname = pm32->indev_name[0] ? pm32->indev_name : pm32->outdev_name; |
| } |
| |
| asprintf(&mParams[0], "ALERT_NAME=%s", alert); |
| asprintf(&mParams[1], "INTERFACE=%s", devname); |
| mSubsystem = strdup("qlog"); |
| mAction = Action::kChange; |
| return true; |
| } |
| |
| static size_t nlAttrLen(const nlattr* nla) { |
| return nla->nla_len - NLA_HDRLEN; |
| } |
| |
| static const uint8_t* nlAttrData(const nlattr* nla) { |
| return reinterpret_cast<const uint8_t*>(nla) + NLA_HDRLEN; |
| } |
| |
| static uint32_t nlAttrU32(const nlattr* nla) { |
| return *reinterpret_cast<const uint32_t*>(nlAttrData(nla)); |
| } |
| |
| /* |
| * Parse a LOCAL_NFLOG_PACKET message. |
| */ |
| bool NetlinkEvent::parseNfPacketMessage(struct nlmsghdr *nh) { |
| int uid = -1; |
| int len = 0; |
| char* raw = nullptr; |
| |
| struct nlattr* uid_attr = findNlAttr(nh, sizeof(struct genlmsghdr), NFULA_UID); |
| if (uid_attr) { |
| uid = ntohl(nlAttrU32(uid_attr)); |
| } |
| |
| struct nlattr* payload = findNlAttr(nh, sizeof(struct genlmsghdr), NFULA_PAYLOAD); |
| if (payload) { |
| /* First 256 bytes is plenty */ |
| len = nlAttrLen(payload); |
| if (len > 256) len = 256; |
| raw = (char*)nlAttrData(payload); |
| } |
| |
| size_t hexSize = 5 + (len * 2); |
| char* hex = (char*)calloc(1, hexSize); |
| strlcpy(hex, "HEX=", hexSize); |
| for (int i = 0; i < len; i++) { |
| hex[4 + (i * 2)] = "0123456789abcdef"[(raw[i] >> 4) & 0xf]; |
| hex[5 + (i * 2)] = "0123456789abcdef"[raw[i] & 0xf]; |
| } |
| |
| asprintf(&mParams[0], "UID=%d", uid); |
| mParams[1] = hex; |
| mSubsystem = strdup("strict"); |
| mAction = Action::kChange; |
| return true; |
| } |
| |
| /* |
| * Parse a RTM_NEWROUTE or RTM_DELROUTE message. |
| */ |
| bool NetlinkEvent::parseRtMessage(const struct nlmsghdr *nh) { |
| uint8_t type = nh->nlmsg_type; |
| const char *msgname = rtMessageName(type); |
| |
| if (type != RTM_NEWROUTE && type != RTM_DELROUTE) { |
| SLOGE("%s: incorrect message type %d (%s)\n", __func__, type, msgname); |
| return false; |
| } |
| |
| struct rtmsg *rtm = (struct rtmsg *) NLMSG_DATA(nh); |
| if (!checkRtNetlinkLength(nh, sizeof(*rtm))) |
| return false; |
| |
| if (// Ignore static routes we've set up ourselves. |
| (rtm->rtm_protocol != RTPROT_KERNEL && |
| rtm->rtm_protocol != RTPROT_RA) || |
| // We're only interested in global unicast routes. |
| (rtm->rtm_scope != RT_SCOPE_UNIVERSE) || |
| (rtm->rtm_type != RTN_UNICAST) || |
| // We don't support source routing. |
| (rtm->rtm_src_len != 0) || |
| // Cloned routes aren't real routes. |
| (rtm->rtm_flags & RTM_F_CLONED)) { |
| return false; |
| } |
| |
| int family = rtm->rtm_family; |
| int prefixLength = rtm->rtm_dst_len; |
| |
| // Currently we only support: destination, (one) next hop, ifindex. |
| char dst[INET6_ADDRSTRLEN] = ""; |
| char gw[INET6_ADDRSTRLEN] = ""; |
| char dev[IFNAMSIZ] = ""; |
| |
| size_t len = RTM_PAYLOAD(nh); |
| struct rtattr *rta; |
| for (rta = RTM_RTA(rtm); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) { |
| switch (rta->rta_type) { |
| case RTA_DST: |
| if (maybeLogDuplicateAttribute(*dst, "RTA_DST", msgname)) |
| continue; |
| if (!inet_ntop(family, RTA_DATA(rta), dst, sizeof(dst))) |
| return false; |
| continue; |
| case RTA_GATEWAY: |
| if (maybeLogDuplicateAttribute(*gw, "RTA_GATEWAY", msgname)) |
| continue; |
| if (!inet_ntop(family, RTA_DATA(rta), gw, sizeof(gw))) |
| return false; |
| continue; |
| case RTA_OIF: |
| if (maybeLogDuplicateAttribute(*dev, "RTA_OIF", msgname)) |
| continue; |
| if (!if_indextoname(* (int *) RTA_DATA(rta), dev)) |
| return false; |
| continue; |
| default: |
| continue; |
| } |
| } |
| |
| // If there's no RTA_DST attribute, then: |
| // - If the prefix length is zero, it's the default route. |
| // - If the prefix length is nonzero, there's something we don't understand. |
| // Ignore the event. |
| if (!*dst && !prefixLength) { |
| if (family == AF_INET) { |
| strncpy(dst, "0.0.0.0", sizeof(dst)); |
| } else if (family == AF_INET6) { |
| strncpy(dst, "::", sizeof(dst)); |
| } |
| } |
| |
| // A useful route must have a destination and at least either a gateway or |
| // an interface. |
| if (!*dst || (!*gw && !*dev)) |
| return false; |
| |
| // Fill in netlink event information. |
| mAction = (type == RTM_NEWROUTE) ? Action::kRouteUpdated : |
| Action::kRouteRemoved; |
| mSubsystem = strdup("net"); |
| asprintf(&mParams[0], "ROUTE=%s/%d", dst, prefixLength); |
| asprintf(&mParams[1], "GATEWAY=%s", (*gw) ? gw : ""); |
| asprintf(&mParams[2], "INTERFACE=%s", (*dev) ? dev : ""); |
| |
| return true; |
| } |
| |
| /* |
| * Parse a RTM_NEWNDUSEROPT message. |
| */ |
| bool NetlinkEvent::parseNdUserOptMessage(const struct nlmsghdr *nh) { |
| struct nduseroptmsg *msg = (struct nduseroptmsg *) NLMSG_DATA(nh); |
| if (!checkRtNetlinkLength(nh, sizeof(*msg))) |
| return false; |
| |
| // Check the length is valid. |
| int len = NLMSG_PAYLOAD(nh, sizeof(*msg)); |
| if (msg->nduseropt_opts_len > len) { |
| SLOGE("RTM_NEWNDUSEROPT invalid length %d > %d\n", |
| msg->nduseropt_opts_len, len); |
| return false; |
| } |
| len = msg->nduseropt_opts_len; |
| |
| // Check address family and packet type. |
| if (msg->nduseropt_family != AF_INET6) { |
| SLOGE("RTM_NEWNDUSEROPT message for unknown family %d\n", |
| msg->nduseropt_family); |
| return false; |
| } |
| |
| if (msg->nduseropt_icmp_type != ND_ROUTER_ADVERT || |
| msg->nduseropt_icmp_code != 0) { |
| SLOGE("RTM_NEWNDUSEROPT message for unknown ICMPv6 type/code %d/%d\n", |
| msg->nduseropt_icmp_type, msg->nduseropt_icmp_code); |
| return false; |
| } |
| |
| // Find the interface name. |
| char ifname[IFNAMSIZ]; |
| if (!if_indextoname(msg->nduseropt_ifindex, ifname)) { |
| SLOGE("RTM_NEWNDUSEROPT on unknown ifindex %d\n", |
| msg->nduseropt_ifindex); |
| return false; |
| } |
| |
| // The kernel sends a separate netlink message for each ND option in the RA. |
| // So only parse the first ND option in the message. |
| struct nd_opt_hdr *opthdr = (struct nd_opt_hdr *) (msg + 1); |
| |
| // The length is in multiples of 8 octets. |
| uint16_t optlen = opthdr->nd_opt_len; |
| if (optlen * 8 > len) { |
| SLOGE("Invalid option length %d > %d for ND option %d\n", |
| optlen * 8, len, opthdr->nd_opt_type); |
| return false; |
| } |
| |
| if (opthdr->nd_opt_type == ND_OPT_RDNSS) { |
| // DNS Servers (RFC 6106). |
| // Each address takes up 2*8 octets, and the header takes up 8 octets. |
| // So for a valid option with one or more addresses, optlen must be |
| // odd and greater than 1. |
| if ((optlen < 3) || !(optlen & 0x1)) { |
| SLOGE("Invalid optlen %d for RDNSS option\n", optlen); |
| return false; |
| } |
| const int numaddrs = (optlen - 1) / 2; |
| |
| // Find the lifetime. |
| struct nd_opt_rdnss *rndss_opt = (struct nd_opt_rdnss *) opthdr; |
| const uint32_t lifetime = ntohl(rndss_opt->nd_opt_rdnss_lifetime); |
| |
| // Construct a comma-separated string of DNS addresses. |
| // Reserve sufficient space for an IPv6 link-local address: all but the |
| // last address are followed by ','; the last is followed by '\0'. |
| static const size_t kMaxSingleAddressLength = |
| INET6_ADDRSTRLEN + strlen("%") + IFNAMSIZ + strlen(","); |
| const size_t bufsize = numaddrs * kMaxSingleAddressLength; |
| char *buf = (char *) malloc(bufsize); |
| if (!buf) { |
| SLOGE("RDNSS option: out of memory\n"); |
| return false; |
| } |
| |
| struct in6_addr *addrs = (struct in6_addr *) (rndss_opt + 1); |
| size_t pos = 0; |
| for (int i = 0; i < numaddrs; i++) { |
| if (i > 0) { |
| buf[pos++] = ','; |
| } |
| inet_ntop(AF_INET6, addrs + i, buf + pos, bufsize - pos); |
| pos += strlen(buf + pos); |
| if (IN6_IS_ADDR_LINKLOCAL(addrs + i)) { |
| buf[pos++] = '%'; |
| pos += strlcpy(buf + pos, ifname, bufsize - pos); |
| } |
| } |
| buf[pos] = '\0'; |
| |
| mAction = Action::kRdnss; |
| mSubsystem = strdup("net"); |
| asprintf(&mParams[0], "INTERFACE=%s", ifname); |
| asprintf(&mParams[1], "LIFETIME=%u", lifetime); |
| asprintf(&mParams[2], "SERVERS=%s", buf); |
| free(buf); |
| } else if (opthdr->nd_opt_type == ND_OPT_DNSSL) { |
| // TODO: support DNSSL. |
| } else if (opthdr->nd_opt_type == ND_OPT_CAPTIVE_PORTAL) { |
| // TODO: support CAPTIVE PORTAL. |
| } else if (opthdr->nd_opt_type == ND_OPT_PREF64) { |
| // TODO: support PREF64. |
| } else { |
| SLOGD("Unknown ND option type %d\n", opthdr->nd_opt_type); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /* |
| * Parse a binary message from a NETLINK_ROUTE netlink socket. |
| * |
| * Note that this function can only parse one message, because the message's |
| * content has to be stored in the class's member variables (mAction, |
| * mSubsystem, etc.). Invalid or unrecognized messages are skipped, but if |
| * there are multiple valid messages in the buffer, only the first one will be |
| * returned. |
| * |
| * TODO: consider only ever looking at the first message. |
| */ |
| bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) { |
| struct nlmsghdr *nh; |
| |
| for (nh = (struct nlmsghdr *) buffer; |
| NLMSG_OK(nh, (unsigned) size) && (nh->nlmsg_type != NLMSG_DONE); |
| nh = NLMSG_NEXT(nh, size)) { |
| |
| if (!rtMessageName(nh->nlmsg_type)) { |
| SLOGD("Unexpected netlink message type %d\n", nh->nlmsg_type); |
| continue; |
| } |
| |
| if (nh->nlmsg_type == RTM_NEWLINK) { |
| if (parseIfInfoMessage(nh)) |
| return true; |
| |
| } else if (nh->nlmsg_type == LOCAL_QLOG_NL_EVENT) { |
| if (parseUlogPacketMessage(nh)) |
| return true; |
| |
| } else if (nh->nlmsg_type == RTM_NEWADDR || |
| nh->nlmsg_type == RTM_DELADDR) { |
| if (parseIfAddrMessage(nh)) |
| return true; |
| |
| } else if (nh->nlmsg_type == RTM_NEWROUTE || |
| nh->nlmsg_type == RTM_DELROUTE) { |
| if (parseRtMessage(nh)) |
| return true; |
| |
| } else if (nh->nlmsg_type == RTM_NEWNDUSEROPT) { |
| if (parseNdUserOptMessage(nh)) |
| return true; |
| |
| } else if (nh->nlmsg_type == LOCAL_NFLOG_PACKET) { |
| if (parseNfPacketMessage(nh)) |
| return true; |
| |
| } |
| } |
| |
| return false; |
| } |
| |
| /* If the string between 'str' and 'end' begins with 'prefixlen' characters |
| * from the 'prefix' array, then return 'str + prefixlen', otherwise return |
| * NULL. |
| */ |
| static const char* |
| has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen) |
| { |
| if ((end - str) >= (ptrdiff_t)prefixlen && |
| (prefixlen == 0 || !memcmp(str, prefix, prefixlen))) { |
| return str + prefixlen; |
| } else { |
| return nullptr; |
| } |
| } |
| |
| /* Same as strlen(x) for constant string literals ONLY */ |
| #define CONST_STRLEN(x) (sizeof(x)-1) |
| |
| /* Convenience macro to call has_prefix with a constant string literal */ |
| #define HAS_CONST_PREFIX(str,end,prefix) has_prefix((str),(end),prefix,CONST_STRLEN(prefix)) |
| |
| |
| /* |
| * Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT |
| * netlink socket. |
| */ |
| bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) { |
| const char *s = buffer; |
| const char *end; |
| int param_idx = 0; |
| int first = 1; |
| |
| if (size == 0) |
| return false; |
| |
| /* Ensure the buffer is zero-terminated, the code below depends on this */ |
| buffer[size-1] = '\0'; |
| |
| end = s + size; |
| while (s < end) { |
| if (first) { |
| const char *p; |
| /* buffer is 0-terminated, no need to check p < end */ |
| for (p = s; *p != '@'; p++) { |
| if (!*p) { /* no '@', should not happen */ |
| return false; |
| } |
| } |
| mPath = strdup(p+1); |
| first = 0; |
| } else { |
| const char* a; |
| if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != nullptr) { |
| if (!strcmp(a, "add")) |
| mAction = Action::kAdd; |
| else if (!strcmp(a, "remove")) |
| mAction = Action::kRemove; |
| else if (!strcmp(a, "change")) |
| mAction = Action::kChange; |
| } else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != nullptr) { |
| if (!ParseInt(a, &mSeq)) { |
| SLOGE("NetlinkEvent::parseAsciiNetlinkMessage: failed to parse SEQNUM=%s", a); |
| } |
| } else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != nullptr) { |
| mSubsystem = strdup(a); |
| } else if (param_idx < NL_PARAMS_MAX) { |
| mParams[param_idx++] = strdup(s); |
| } |
| } |
| s += strlen(s) + 1; |
| } |
| return true; |
| } |
| |
| bool NetlinkEvent::decode(char *buffer, int size, int format) { |
| if (format == NetlinkListener::NETLINK_FORMAT_BINARY |
| || format == NetlinkListener::NETLINK_FORMAT_BINARY_UNICAST) { |
| return parseBinaryNetlinkMessage(buffer, size); |
| } else { |
| return parseAsciiNetlinkMessage(buffer, size); |
| } |
| } |
| |
| const char *NetlinkEvent::findParam(const char *paramName) { |
| size_t len = strlen(paramName); |
| for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != nullptr; ++i) { |
| const char *ptr = mParams[i] + len; |
| if (!strncmp(mParams[i], paramName, len) && *ptr == '=') |
| return ++ptr; |
| } |
| |
| SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName); |
| return nullptr; |
| } |
| |
| nlattr* NetlinkEvent::findNlAttr(const nlmsghdr* nh, size_t hdrlen, uint16_t attr) { |
| if (nh == nullptr || NLMSG_HDRLEN + NLMSG_ALIGN(hdrlen) > SSIZE_MAX) { |
| return nullptr; |
| } |
| |
| // Skip header, padding, and family header. |
| const ssize_t NLA_START = NLMSG_HDRLEN + NLMSG_ALIGN(hdrlen); |
| ssize_t left = nh->nlmsg_len - NLA_START; |
| uint8_t* hdr = ((uint8_t*)nh) + NLA_START; |
| |
| while (left >= NLA_HDRLEN) { |
| nlattr* nla = (nlattr*)hdr; |
| if (nla->nla_type == attr) { |
| return nla; |
| } |
| |
| hdr += NLA_ALIGN(nla->nla_len); |
| left -= NLA_ALIGN(nla->nla_len); |
| } |
| |
| return nullptr; |
| } |