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kernel_netlink.c
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kernel_netlink.c
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/* Kernel communication using netlink interface.
* Copyright (C) 1999 Kunihiro Ishiguro
*
* This file is part of GNU Zebra.
*
* GNU Zebra is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* GNU Zebra is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <zebra.h>
#if defined(HANDLE_NETLINK_FUZZING)
#include <stdio.h>
#include <string.h>
#endif /* HANDLE_NETLINK_FUZZING */
#ifdef HAVE_NETLINK
#include "linklist.h"
#include "if.h"
#include "log.h"
#include "prefix.h"
#include "connected.h"
#include "table.h"
#include "memory.h"
#include "zebra_memory.h"
#include "rib.h"
#include "thread.h"
#include "privs.h"
#include "nexthop.h"
#include "vrf.h"
#include "mpls.h"
#include "lib_errors.h"
//#include "zebra/zserv.h"
#include "zebra/zebra_router.h"
#include "zebra/zebra_ns.h"
#include "zebra/zebra_vrf.h"
#include "zebra/rt.h"
#include "zebra/debug.h"
#include "zebra/kernel_netlink.h"
#include "zebra/rt_netlink.h"
#include "zebra/if_netlink.h"
#include "zebra/rule_netlink.h"
#include "zebra/zebra_errors.h"
#ifndef SO_RCVBUFFORCE
#define SO_RCVBUFFORCE (33)
#endif
/* Hack for GNU libc version 2. */
#ifndef MSG_TRUNC
#define MSG_TRUNC 0x20
#endif /* MSG_TRUNC */
#ifndef NLMSG_TAIL
#define NLMSG_TAIL(nmsg) \
((struct rtattr *)(((uint8_t *)(nmsg)) \
+ NLMSG_ALIGN((nmsg)->nlmsg_len)))
#endif
#ifndef RTA_TAIL
#define RTA_TAIL(rta) \
((struct rtattr *)(((uint8_t *)(rta)) + RTA_ALIGN((rta)->rta_len)))
#endif
#ifndef RTNL_FAMILY_IP6MR
#define RTNL_FAMILY_IP6MR 129
#endif
#ifndef RTPROT_MROUTED
#define RTPROT_MROUTED 17
#endif
static const struct message nlmsg_str[] = {{RTM_NEWROUTE, "RTM_NEWROUTE"},
{RTM_DELROUTE, "RTM_DELROUTE"},
{RTM_GETROUTE, "RTM_GETROUTE"},
{RTM_NEWLINK, "RTM_NEWLINK"},
{RTM_DELLINK, "RTM_DELLINK"},
{RTM_GETLINK, "RTM_GETLINK"},
{RTM_NEWADDR, "RTM_NEWADDR"},
{RTM_DELADDR, "RTM_DELADDR"},
{RTM_GETADDR, "RTM_GETADDR"},
{RTM_NEWNEIGH, "RTM_NEWNEIGH"},
{RTM_DELNEIGH, "RTM_DELNEIGH"},
{RTM_GETNEIGH, "RTM_GETNEIGH"},
{RTM_NEWRULE, "RTM_NEWRULE"},
{RTM_DELRULE, "RTM_DELRULE"},
{RTM_GETRULE, "RTM_GETRULE"},
{0}};
static const struct message rtproto_str[] = {
{RTPROT_REDIRECT, "redirect"},
{RTPROT_KERNEL, "kernel"},
{RTPROT_BOOT, "boot"},
{RTPROT_STATIC, "static"},
{RTPROT_GATED, "GateD"},
{RTPROT_RA, "router advertisement"},
{RTPROT_MRT, "MRT"},
{RTPROT_ZEBRA, "Zebra"},
#ifdef RTPROT_BIRD
{RTPROT_BIRD, "BIRD"},
#endif /* RTPROT_BIRD */
{RTPROT_MROUTED, "mroute"},
{RTPROT_BGP, "BGP"},
{RTPROT_OSPF, "OSPF"},
{RTPROT_ISIS, "IS-IS"},
{RTPROT_RIP, "RIP"},
{RTPROT_RIPNG, "RIPNG"},
{RTPROT_ZSTATIC, "static"},
{0}};
static const struct message family_str[] = {{AF_INET, "ipv4"},
{AF_INET6, "ipv6"},
{AF_BRIDGE, "bridge"},
{RTNL_FAMILY_IPMR, "ipv4MR"},
{RTNL_FAMILY_IP6MR, "ipv6MR"},
{0}};
static const struct message rttype_str[] = {{RTN_UNICAST, "unicast"},
{RTN_MULTICAST, "multicast"},
{0}};
extern struct thread_master *master;
extern uint32_t nl_rcvbufsize;
extern struct zebra_privs_t zserv_privs;
int netlink_talk_filter(struct nlmsghdr *h, ns_id_t ns_id, int startup)
{
/*
* This is an error condition that must be handled during
* development.
*
* The netlink_talk_filter function is used for communication
* down the netlink_cmd pipe and we are expecting
* an ack being received. So if we get here
* then we did not receive the ack and instead
* received some other message in an unexpected
* way.
*/
zlog_debug("%s: ignoring message type 0x%04x(%s) NS %u", __func__,
h->nlmsg_type, nl_msg_type_to_str(h->nlmsg_type), ns_id);
return 0;
}
static int netlink_recvbuf(struct nlsock *nl, uint32_t newsize)
{
uint32_t oldsize;
socklen_t newlen = sizeof(newsize);
socklen_t oldlen = sizeof(oldsize);
int ret;
ret = getsockopt(nl->sock, SOL_SOCKET, SO_RCVBUF, &oldsize, &oldlen);
if (ret < 0) {
flog_err_sys(EC_LIB_SOCKET,
"Can't get %s receive buffer size: %s", nl->name,
safe_strerror(errno));
return -1;
}
/* Try force option (linux >= 2.6.14) and fall back to normal set */
frr_elevate_privs(&zserv_privs) {
ret = setsockopt(nl->sock, SOL_SOCKET, SO_RCVBUFFORCE,
&nl_rcvbufsize,
sizeof(nl_rcvbufsize));
}
if (ret < 0)
ret = setsockopt(nl->sock, SOL_SOCKET, SO_RCVBUF,
&nl_rcvbufsize, sizeof(nl_rcvbufsize));
if (ret < 0) {
flog_err_sys(EC_LIB_SOCKET,
"Can't set %s receive buffer size: %s", nl->name,
safe_strerror(errno));
return -1;
}
ret = getsockopt(nl->sock, SOL_SOCKET, SO_RCVBUF, &newsize, &newlen);
if (ret < 0) {
flog_err_sys(EC_LIB_SOCKET,
"Can't get %s receive buffer size: %s", nl->name,
safe_strerror(errno));
return -1;
}
zlog_info("Setting netlink socket receive buffer size: %u -> %u",
oldsize, newsize);
return 0;
}
/* Make socket for Linux netlink interface. */
static int netlink_socket(struct nlsock *nl, unsigned long groups,
ns_id_t ns_id)
{
int ret;
struct sockaddr_nl snl;
int sock;
int namelen;
frr_elevate_privs(&zserv_privs) {
sock = ns_socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE, ns_id);
if (sock < 0) {
zlog_err("Can't open %s socket: %s", nl->name,
safe_strerror(errno));
return -1;
}
memset(&snl, 0, sizeof snl);
snl.nl_family = AF_NETLINK;
snl.nl_groups = groups;
/* Bind the socket to the netlink structure for anything. */
ret = bind(sock, (struct sockaddr *)&snl, sizeof snl);
}
if (ret < 0) {
zlog_err("Can't bind %s socket to group 0x%x: %s", nl->name,
snl.nl_groups, safe_strerror(errno));
close(sock);
return -1;
}
/* multiple netlink sockets will have different nl_pid */
namelen = sizeof snl;
ret = getsockname(sock, (struct sockaddr *)&snl, (socklen_t *)&namelen);
if (ret < 0 || namelen != sizeof snl) {
flog_err_sys(EC_LIB_SOCKET, "Can't get %s socket name: %s",
nl->name, safe_strerror(errno));
close(sock);
return -1;
}
nl->snl = snl;
nl->sock = sock;
return ret;
}
static int netlink_information_fetch(struct nlmsghdr *h, ns_id_t ns_id,
int startup)
{
/*
* When we handle new message types here
* because we are starting to install them
* then lets check the netlink_install_filter
* and see if we should add the corresponding
* allow through entry there.
* Probably not needed to do but please
* think about it.
*/
switch (h->nlmsg_type) {
case RTM_NEWROUTE:
return netlink_route_change(h, ns_id, startup);
case RTM_DELROUTE:
return netlink_route_change(h, ns_id, startup);
case RTM_NEWLINK:
return netlink_link_change(h, ns_id, startup);
case RTM_DELLINK:
return netlink_link_change(h, ns_id, startup);
case RTM_NEWADDR:
return netlink_interface_addr(h, ns_id, startup);
case RTM_DELADDR:
return netlink_interface_addr(h, ns_id, startup);
case RTM_NEWNEIGH:
return netlink_neigh_change(h, ns_id);
case RTM_DELNEIGH:
return netlink_neigh_change(h, ns_id);
case RTM_NEWRULE:
return netlink_rule_change(h, ns_id, startup);
case RTM_DELRULE:
return netlink_rule_change(h, ns_id, startup);
default:
/*
* If we have received this message then
* we have made a mistake during development
* and we need to write some code to handle
* this message type or not ask for
* it to be sent up to us
*/
flog_err(EC_ZEBRA_UNKNOWN_NLMSG,
"Unknown netlink nlmsg_type %s(%d) vrf %u\n",
nl_msg_type_to_str(h->nlmsg_type), h->nlmsg_type,
ns_id);
break;
}
return 0;
}
#if defined(HANDLE_NETLINK_FUZZING)
/* Using globals here to avoid adding function parameters */
/* Keep distinct filenames for netlink fuzzy collection */
static unsigned int netlink_file_counter = 1;
/* File name to read fuzzed netlink from */
static char netlink_fuzz_file[MAXPATHLEN] = "";
/* Flag for whether to read from file or not */
bool netlink_read;
/**
* netlink_read_init() - Starts the message parser
* @fname: Filename to read.
*/
void netlink_read_init(const char *fname)
{
struct zebra_dplane_info dp_info;
snprintf(netlink_fuzz_file, MAXPATHLEN, "%s", fname);
/* Creating this fake socket for testing purposes */
struct zebra_ns *zns = zebra_ns_lookup(NS_DEFAULT);
/* Capture key info from zns struct */
zebra_dplane_info_from_zns(&dp_info, zns, false);
netlink_parse_info(netlink_information_fetch, &zns->netlink,
&dp_info, 1, 0);
}
/**
* netlink_write_incoming() - Writes all data received from netlink to a file
* @buf: Data from netlink.
* @size: Size of data.
* @counter: Counter for keeping filenames distinct.
*/
static void netlink_write_incoming(const char *buf, const unsigned int size,
unsigned int counter)
{
char fname[MAXPATHLEN];
FILE *f;
snprintf(fname, MAXPATHLEN, "%s/%s_%u", DAEMON_VTY_DIR, "netlink",
counter);
frr_elevate_privs(&zserv_privs) {
f = fopen(fname, "w");
}
if (f) {
fwrite(buf, 1, size, f);
fclose(f);
}
}
/**
* netlink_read_file() - Reads netlink data from file
* @buf: Netlink buffer being overwritten.
* @fname: File name to read from.
*
* Return: Size of file.
*/
static long netlink_read_file(char *buf, const char *fname)
{
FILE *f;
long file_bytes = -1;
frr_elevate_privs(&zserv_privs) {
f = fopen(fname, "r");
}
if (f) {
fseek(f, 0, SEEK_END);
file_bytes = ftell(f);
rewind(f);
fread(buf, NL_RCV_PKT_BUF_SIZE, 1, f);
fclose(f);
}
return file_bytes;
}
#endif /* HANDLE_NETLINK_FUZZING */
static int kernel_read(struct thread *thread)
{
struct zebra_ns *zns = (struct zebra_ns *)THREAD_ARG(thread);
struct zebra_dplane_info dp_info;
/* Capture key info from ns struct */
zebra_dplane_info_from_zns(&dp_info, zns, false);
netlink_parse_info(netlink_information_fetch, &zns->netlink, &dp_info,
5, 0);
zns->t_netlink = NULL;
thread_add_read(zrouter.master, kernel_read, zns, zns->netlink.sock,
&zns->t_netlink);
return 0;
}
/*
* Filter out messages from self that occur on listener socket,
* caused by our actions on the command socket(s)
*
* When we add new Netlink message types we probably
* do not need to add them here as that we are filtering
* on the routes we actually care to receive( which is rarer
* then the normal course of operations). We are intentionally
* allowing some messages from ourselves through
* ( I'm looking at you Interface based netlink messages )
* so that we only had to write one way to handle incoming
* address add/delete changes.
*/
static void netlink_install_filter(int sock, __u32 pid, __u32 dplane_pid)
{
/*
* BPF_JUMP instructions and where you jump to are based upon
* 0 as being the next statement. So count from 0. Writing
* this down because every time I look at this I have to
* re-remember it.
*/
struct sock_filter filter[] = {
/*
* Logic:
* if (nlmsg_pid == pid ||
* nlmsg_pid == dplane_pid) {
* if (the incoming nlmsg_type ==
* RTM_NEWADDR | RTM_DELADDR)
* keep this message
* else
* skip this message
* } else
* keep this netlink message
*/
/*
* 0: Load the nlmsg_pid into the BPF register
*/
BPF_STMT(BPF_LD | BPF_ABS | BPF_W,
offsetof(struct nlmsghdr, nlmsg_pid)),
/*
* 1: Compare to pid
*/
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, htonl(pid), 1, 0),
/*
* 2: Compare to dplane pid
*/
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, htonl(dplane_pid), 0, 4),
/*
* 3: Load the nlmsg_type into BPF register
*/
BPF_STMT(BPF_LD | BPF_ABS | BPF_H,
offsetof(struct nlmsghdr, nlmsg_type)),
/*
* 4: Compare to RTM_NEWADDR
*/
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, htons(RTM_NEWADDR), 2, 0),
/*
* 5: Compare to RTM_DELADDR
*/
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, htons(RTM_DELADDR), 1, 0),
/*
* 6: This is the end state of we want to skip the
* message
*/
BPF_STMT(BPF_RET | BPF_K, 0),
/* 7: This is the end state of we want to keep
* the message
*/
BPF_STMT(BPF_RET | BPF_K, 0xffff),
};
struct sock_fprog prog = {
.len = array_size(filter), .filter = filter,
};
if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &prog, sizeof(prog))
< 0)
flog_err_sys(EC_LIB_SOCKET, "Can't install socket filter: %s\n",
safe_strerror(errno));
}
void netlink_parse_rtattr(struct rtattr **tb, int max, struct rtattr *rta,
int len)
{
while (RTA_OK(rta, len)) {
if (rta->rta_type <= max)
tb[rta->rta_type] = rta;
rta = RTA_NEXT(rta, len);
}
}
/**
* netlink_parse_rtattr_nested() - Parses a nested route attribute
* @tb: Pointer to array for storing rtattr in.
* @max: Max number to store.
* @rta: Pointer to rtattr to look for nested items in.
*/
void netlink_parse_rtattr_nested(struct rtattr **tb, int max,
struct rtattr *rta)
{
netlink_parse_rtattr(tb, max, RTA_DATA(rta), RTA_PAYLOAD(rta));
}
int addattr_l(struct nlmsghdr *n, unsigned int maxlen, int type,
const void *data, unsigned int alen)
{
int len;
struct rtattr *rta;
len = RTA_LENGTH(alen);
if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen)
return -1;
rta = (struct rtattr *)(((char *)n) + NLMSG_ALIGN(n->nlmsg_len));
rta->rta_type = type;
rta->rta_len = len;
if (data)
memcpy(RTA_DATA(rta), data, alen);
else
assert(alen == 0);
n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
return 0;
}
int rta_addattr_l(struct rtattr *rta, unsigned int maxlen, int type,
const void *data, unsigned int alen)
{
unsigned int len;
struct rtattr *subrta;
len = RTA_LENGTH(alen);
if (RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len) > maxlen)
return -1;
subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
subrta->rta_type = type;
subrta->rta_len = len;
if (data)
memcpy(RTA_DATA(subrta), data, alen);
else
assert(alen == 0);
rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
return 0;
}
int addattr16(struct nlmsghdr *n, unsigned int maxlen, int type, uint16_t data)
{
return addattr_l(n, maxlen, type, &data, sizeof(uint16_t));
}
int addattr32(struct nlmsghdr *n, unsigned int maxlen, int type, int data)
{
return addattr_l(n, maxlen, type, &data, sizeof(uint32_t));
}
struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
{
struct rtattr *nest = NLMSG_TAIL(n);
addattr_l(n, maxlen, type, NULL, 0);
return nest;
}
int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
{
nest->rta_len = (uint8_t *)NLMSG_TAIL(n) - (uint8_t *)nest;
return n->nlmsg_len;
}
struct rtattr *rta_nest(struct rtattr *rta, int maxlen, int type)
{
struct rtattr *nest = RTA_TAIL(rta);
rta_addattr_l(rta, maxlen, type, NULL, 0);
return nest;
}
int rta_nest_end(struct rtattr *rta, struct rtattr *nest)
{
nest->rta_len = (uint8_t *)RTA_TAIL(rta) - (uint8_t *)nest;
return rta->rta_len;
}
const char *nl_msg_type_to_str(uint16_t msg_type)
{
return lookup_msg(nlmsg_str, msg_type, "");
}
const char *nl_rtproto_to_str(uint8_t rtproto)
{
return lookup_msg(rtproto_str, rtproto, "");
}
const char *nl_family_to_str(uint8_t family)
{
return lookup_msg(family_str, family, "");
}
const char *nl_rttype_to_str(uint8_t rttype)
{
return lookup_msg(rttype_str, rttype, "");
}
#define NL_OK(nla, len) \
((len) >= (int)sizeof(struct nlattr) \
&& (nla)->nla_len >= sizeof(struct nlattr) \
&& (nla)->nla_len <= (len))
#define NL_NEXT(nla, attrlen) \
((attrlen) -= RTA_ALIGN((nla)->nla_len), \
(struct nlattr *)(((char *)(nla)) + RTA_ALIGN((nla)->nla_len)))
#define NL_RTA(r) \
((struct nlattr *)(((char *)(r)) \
+ NLMSG_ALIGN(sizeof(struct nlmsgerr))))
static void netlink_parse_nlattr(struct nlattr **tb, int max,
struct nlattr *nla, int len)
{
while (NL_OK(nla, len)) {
if (nla->nla_type <= max)
tb[nla->nla_type] = nla;
nla = NL_NEXT(nla, len);
}
}
static void netlink_parse_extended_ack(struct nlmsghdr *h)
{
struct nlattr *tb[NLMSGERR_ATTR_MAX + 1];
const struct nlmsgerr *err =
(const struct nlmsgerr *)((uint8_t *)h
+ NLMSG_ALIGN(
sizeof(struct nlmsghdr)));
const struct nlmsghdr *err_nlh = NULL;
uint32_t hlen = sizeof(*err);
const char *msg = NULL;
uint32_t off = 0;
if (!(h->nlmsg_flags & NLM_F_CAPPED))
hlen += h->nlmsg_len - NLMSG_ALIGN(sizeof(struct nlmsghdr));
memset(tb, 0, sizeof(tb));
netlink_parse_nlattr(tb, NLMSGERR_ATTR_MAX, NL_RTA(h), hlen);
if (tb[NLMSGERR_ATTR_MSG])
msg = (const char *)RTA_DATA(tb[NLMSGERR_ATTR_MSG]);
if (tb[NLMSGERR_ATTR_OFFS]) {
off = *(uint32_t *)RTA_DATA(tb[NLMSGERR_ATTR_OFFS]);
if (off > h->nlmsg_len) {
zlog_err("Invalid offset for NLMSGERR_ATTR_OFFS");
} else if (!(h->nlmsg_flags & NLM_F_CAPPED)) {
/*
* Header of failed message
* we are not doing anything currently with it
* but noticing it for later.
*/
err_nlh = &err->msg;
zlog_debug("%s: Received %s extended Ack",
__PRETTY_FUNCTION__,
nl_msg_type_to_str(err_nlh->nlmsg_type));
}
}
if (msg && *msg != '\0') {
bool is_err = !!err->error;
if (is_err)
zlog_err("Extended Error: %s", msg);
else
flog_warn(EC_ZEBRA_NETLINK_EXTENDED_WARNING,
"Extended Warning: %s", msg);
}
}
/*
* netlink_parse_info
*
* Receive message from netlink interface and pass those information
* to the given function.
*
* filter -> Function to call to read the results
* nl -> netlink socket information
* zns -> The zebra namespace data
* count -> How many we should read in, 0 means as much as possible
* startup -> Are we reading in under startup conditions? passed to
* the filter.
*/
int netlink_parse_info(int (*filter)(struct nlmsghdr *, ns_id_t, int),
const struct nlsock *nl,
const struct zebra_dplane_info *zns,
int count, int startup)
{
int status;
int ret = 0;
int error;
int read_in = 0;
while (1) {
char buf[NL_RCV_PKT_BUF_SIZE];
struct iovec iov = {.iov_base = buf, .iov_len = sizeof buf};
struct sockaddr_nl snl;
struct msghdr msg = {.msg_name = (void *)&snl,
.msg_namelen = sizeof snl,
.msg_iov = &iov,
.msg_iovlen = 1};
struct nlmsghdr *h;
if (count && read_in >= count)
return 0;
#if defined(HANDLE_NETLINK_FUZZING)
/* Check if reading and filename is set */
if (netlink_read && '\0' != netlink_fuzz_file[0]) {
zlog_debug("Reading netlink fuzz file");
status = netlink_read_file(buf, netlink_fuzz_file);
snl.nl_pid = 0;
} else {
status = recvmsg(nl->sock, &msg, 0);
}
#else
status = recvmsg(nl->sock, &msg, 0);
#endif /* HANDLE_NETLINK_FUZZING */
if (status < 0) {
if (errno == EINTR)
continue;
if (errno == EWOULDBLOCK || errno == EAGAIN)
break;
flog_err(EC_ZEBRA_RECVMSG_OVERRUN,
"%s recvmsg overrun: %s", nl->name,
safe_strerror(errno));
/*
* In this case we are screwed.
* There is no good way to
* recover zebra at this point.
*/
exit(-1);
continue;
}
if (status == 0) {
flog_err_sys(EC_LIB_SOCKET, "%s EOF", nl->name);
return -1;
}
if (msg.msg_namelen != sizeof snl) {
flog_err(EC_ZEBRA_NETLINK_LENGTH_ERROR,
"%s sender address length error: length %d",
nl->name, msg.msg_namelen);
return -1;
}
if (IS_ZEBRA_DEBUG_KERNEL_MSGDUMP_RECV) {
zlog_debug("%s: << netlink message dump [recv]",
__func__);
zlog_hexdump(buf, status);
}
#if defined(HANDLE_NETLINK_FUZZING)
if (!netlink_read) {
zlog_debug("Writing incoming netlink message");
netlink_write_incoming(buf, status,
netlink_file_counter++);
}
#endif /* HANDLE_NETLINK_FUZZING */
read_in++;
for (h = (struct nlmsghdr *)buf;
(status >= 0 && NLMSG_OK(h, (unsigned int)status));
h = NLMSG_NEXT(h, status)) {
/* Finish of reading. */
if (h->nlmsg_type == NLMSG_DONE)
return ret;
/* Error handling. */
if (h->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err =
(struct nlmsgerr *)NLMSG_DATA(h);
int errnum = err->error;
int msg_type = err->msg.nlmsg_type;
if (h->nlmsg_len
< NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
flog_err(EC_ZEBRA_NETLINK_LENGTH_ERROR,
"%s error: message truncated",
nl->name);
return -1;
}
/*
* Parse the extended information before
* we actually handle it.
* At this point in time we do not
* do anything other than report the
* issue.
*/
if (h->nlmsg_flags & NLM_F_ACK_TLVS)
netlink_parse_extended_ack(h);
/* If the error field is zero, then this is an
* ACK */
if (err->error == 0) {
if (IS_ZEBRA_DEBUG_KERNEL) {
zlog_debug(
"%s: %s ACK: type=%s(%u), seq=%u, pid=%u",
__FUNCTION__, nl->name,
nl_msg_type_to_str(
err->msg.nlmsg_type),
err->msg.nlmsg_type,
err->msg.nlmsg_seq,
err->msg.nlmsg_pid);
}
/* return if not a multipart message,
* otherwise continue */
if (!(h->nlmsg_flags & NLM_F_MULTI))
return 0;
continue;
}
/* Deal with errors that occur because of races
* in link handling */
if (zns->is_cmd
&& ((msg_type == RTM_DELROUTE
&& (-errnum == ENODEV
|| -errnum == ESRCH))
|| (msg_type == RTM_NEWROUTE
&& (-errnum == ENETDOWN
|| -errnum == EEXIST)))) {
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"%s: error: %s type=%s(%u), seq=%u, pid=%u",
nl->name,
safe_strerror(-errnum),
nl_msg_type_to_str(
msg_type),
msg_type,
err->msg.nlmsg_seq,
err->msg.nlmsg_pid);
return 0;
}
/* We see RTM_DELNEIGH when shutting down an
* interface with an IPv4
* link-local. The kernel should have already
* deleted the neighbor
* so do not log these as an error.
*/
if (msg_type == RTM_DELNEIGH
|| (zns->is_cmd && msg_type == RTM_NEWROUTE
&& (-errnum == ESRCH
|| -errnum == ENETUNREACH))) {
/* This is known to happen in some
* situations, don't log
* as error.
*/
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"%s error: %s, type=%s(%u), seq=%u, pid=%u",
nl->name,
safe_strerror(-errnum),
nl_msg_type_to_str(
msg_type),
msg_type,
err->msg.nlmsg_seq,
err->msg.nlmsg_pid);
} else
flog_err(
EC_ZEBRA_UNEXPECTED_MESSAGE,
"%s error: %s, type=%s(%u), seq=%u, pid=%u",
nl->name,
safe_strerror(-errnum),
nl_msg_type_to_str(msg_type),
msg_type, err->msg.nlmsg_seq,
err->msg.nlmsg_pid);
return -1;
}
/* OK we got netlink message. */
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"netlink_parse_info: %s type %s(%u), len=%d, seq=%u, pid=%u",
nl->name,
nl_msg_type_to_str(h->nlmsg_type),
h->nlmsg_type, h->nlmsg_len,
h->nlmsg_seq, h->nlmsg_pid);
/*
* Ignore messages that maybe sent from
* other actors besides the kernel
*/
if (snl.nl_pid != 0) {
zlog_debug("Ignoring message from pid %u",
snl.nl_pid);
continue;
}
error = (*filter)(h, zns->ns_id, startup);
if (error < 0) {
zlog_debug("%s filter function error",
nl->name);
ret = error;
}
}
/* After error care. */
if (msg.msg_flags & MSG_TRUNC) {
flog_err(EC_ZEBRA_NETLINK_LENGTH_ERROR,
"%s error: message truncated", nl->name);
continue;
}
if (status) {
flog_err(EC_ZEBRA_NETLINK_LENGTH_ERROR,
"%s error: data remnant size %d", nl->name,
status);
return -1;
}
}
return ret;
}
/*
* netlink_talk_info
*
* sendmsg() to netlink socket then recvmsg().
* Calls netlink_parse_info to parse returned data
*
* filter -> The filter to read final results from kernel
* nlmsghdr -> The data to send to the kernel
* dp_info -> The dataplane and netlink socket information
* startup -> Are we reading in under startup conditions
* This is passed through eventually to filter.
*/
int netlink_talk_info(int (*filter)(struct nlmsghdr *, ns_id_t, int startup),
struct nlmsghdr *n,
const struct zebra_dplane_info *dp_info, int startup)
{
int status = 0;
struct sockaddr_nl snl;
struct iovec iov;
struct msghdr msg;
int save_errno = 0;
const struct nlsock *nl;
memset(&snl, 0, sizeof snl);
memset(&iov, 0, sizeof iov);
memset(&msg, 0, sizeof msg);
iov.iov_base = n;
iov.iov_len = n->nlmsg_len;
msg.msg_name = (void *)&snl;
msg.msg_namelen = sizeof snl;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
snl.nl_family = AF_NETLINK;
nl = &(dp_info->nls);
n->nlmsg_seq = nl->seq;
n->nlmsg_pid = nl->snl.nl_pid;
if (IS_ZEBRA_DEBUG_KERNEL)
zlog_debug(
"netlink_talk: %s type %s(%u), len=%d seq=%u flags 0x%x",
nl->name, nl_msg_type_to_str(n->nlmsg_type),
n->nlmsg_type, n->nlmsg_len, n->nlmsg_seq,
n->nlmsg_flags);
/* Send message to netlink interface. */
frr_elevate_privs(&zserv_privs) {
status = sendmsg(nl->sock, &msg, 0);
save_errno = errno;
}
if (IS_ZEBRA_DEBUG_KERNEL_MSGDUMP_SEND) {
zlog_debug("%s: >> netlink message dump [sent]", __func__);
zlog_hexdump(n, n->nlmsg_len);
}
if (status < 0) {
flog_err_sys(EC_LIB_SOCKET, "netlink_talk sendmsg() error: %s",
safe_strerror(save_errno));
return -1;
}
/*
* Get reply from netlink socket.
* The reply should either be an acknowlegement or an error.
*/
return netlink_parse_info(filter, nl, dp_info, 0, startup);
}
/*
* Synchronous version of netlink_talk_info. Converts args to suit the