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platform_system_core/libsysutils/src/NetlinkEvent.cpp

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/*
* 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.
*/
#include <stdlib.h>
#include <string.h>
#define LOG_TAG "NetlinkEvent"
#include <cutils/log.h>
#include <sysutils/NetlinkEvent.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/icmp6.h>
#include <arpa/inet.h>
#include <net/if.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/netfilter_ipv4/ipt_ULOG.h>
/* 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;
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <netlink/attr.h>
#include <netlink/genl/genl.h>
#include <netlink/handlers.h>
#include <netlink/msg.h>
// STOPSHIP: remove these deprecated constants once we have updated prebuilts
const int NetlinkEvent::NlActionUnknown = static_cast<int>(Action::kUnknown);
const int NetlinkEvent::NlActionAdd = static_cast<int>(Action::kAdd);
const int NetlinkEvent::NlActionRemove = static_cast<int>(Action::kRemove);
const int NetlinkEvent::NlActionChange = static_cast<int>(Action::kChange);
const int NetlinkEvent::NlActionLinkDown = static_cast<int>(Action::kLinkDown);
const int NetlinkEvent::NlActionLinkUp = static_cast<int>(Action::kLinkUp);
const int NetlinkEvent::NlActionAddressUpdated = static_cast<int>(Action::kAddressUpdated);
const int NetlinkEvent::NlActionAddressRemoved = static_cast<int>(Action::kAddressRemoved);
const int NetlinkEvent::NlActionRdnss = static_cast<int>(Action::kRdnss);
const int NetlinkEvent::NlActionRouteUpdated = static_cast<int>(Action::kRouteUpdated);
const int NetlinkEvent::NlActionRouteRemoved = static_cast<int>(Action::kRouteRemoved);
NetlinkEvent::NetlinkEvent() {
mAction = Action::kUnknown;
memset(mParams, 0, sizeof(mParams));
mPath = NULL;
mSubsystem = NULL;
}
NetlinkEvent::~NetlinkEvent() {
int i;
if (mPath)
free(mPath);
if (mSubsystem)
free(mSubsystem);
for (i = 0; i < NL_PARAMS_MAX; i++) {
if (!mParams[i])
break;
free(mParams[i]);
}
}
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 NULL;
}
#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));
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 = NULL;
char addrstr[INET6_ADDRSTRLEN] = "";
char ifname[IFNAMSIZ];
if (!checkRtNetlinkLength(nh, sizeof(*ifaddr)))
return false;
// Sanity check.
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);
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)) {
SLOGE("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
return false;
}
} 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);
}
}
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", ifaddr->ifa_flags);
asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope);
if (cacheinfo) {
asprintf(&mParams[4], "PREFERRED=%u", cacheinfo->ifa_prefered);
asprintf(&mParams[5], "VALID=%u", cacheinfo->ifa_valid);
asprintf(&mParams[6], "CSTAMP=%u", cacheinfo->cstamp);
asprintf(&mParams[7], "TSTAMP=%u", cacheinfo->tstamp);
}
return true;
}
/*
* Parse a QLOG_NL_EVENT message.
*/
bool NetlinkEvent::parseUlogPacketMessage(const struct nlmsghdr *nh) {
const char *devname;
ulog_packet_msg_t *pm = (ulog_packet_msg_t *) NLMSG_DATA(nh);
if (!checkRtNetlinkLength(nh, sizeof(*pm)))
return false;
devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
asprintf(&mParams[1], "INTERFACE=%s", devname);
mSubsystem = strdup("qlog");
mAction = Action::kChange;
return true;
}
/*
* Parse a LOCAL_NFLOG_PACKET message.
*/
bool NetlinkEvent::parseNfPacketMessage(struct nlmsghdr *nh) {
int uid = -1;
int len = 0;
char* raw = NULL;
struct nlattr *uid_attr = nlmsg_find_attr(nh, sizeof(struct genlmsghdr), NFULA_UID);
if (uid_attr) {
uid = ntohl(nla_get_u32(uid_attr));
}
struct nlattr *payload = nlmsg_find_attr(nh, sizeof(struct genlmsghdr), NFULA_PAYLOAD);
if (payload) {
/* First 256 bytes is plenty */
len = nla_len(payload);
if (len > 256) len = 256;
raw = (char*) nla_data(payload);
}
char* hex = (char*) calloc(1, 5 + (len * 2));
strcpy(hex, "HEX=");
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);
// Sanity check.
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;
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;
}
int numaddrs = (optlen - 1) / 2;
// Find the lifetime.
struct nd_opt_rdnss *rndss_opt = (struct nd_opt_rdnss *) opthdr;
uint32_t lifetime = ntohl(rndss_opt->nd_opt_rdnss_lifetime);
// Construct "SERVERS=<comma-separated string of DNS addresses>".
// Reserve (INET6_ADDRSTRLEN + 1) chars for each address: all but the
// the last address are followed by ','; the last is followed by '\0'.
static const char kServerTag[] = "SERVERS=";
static const int kTagLength = sizeof(kServerTag) - 1;
int bufsize = kTagLength + numaddrs * (INET6_ADDRSTRLEN + 1);
char *buf = (char *) malloc(bufsize);
if (!buf) {
SLOGE("RDNSS option: out of memory\n");
return false;
}
strcpy(buf, kServerTag);
int pos = kTagLength;
struct in6_addr *addrs = (struct in6_addr *) (rndss_opt + 1);
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);
}
buf[pos] = '\0';
mAction = Action::kRdnss;
mSubsystem = strdup("net");
asprintf(&mParams[0], "INTERFACE=%s", ifname);
asprintf(&mParams[1], "LIFETIME=%u", lifetime);
mParams[2] = buf;
} 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 && !memcmp(str, prefix, prefixlen))
return str + prefixlen;
else
return NULL;
}
/* 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=")) != NULL) {
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=")) != NULL) {
mSeq = atoi(a);
} else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
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] != NULL; ++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 NULL;
}
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