linux/net/ipv4/tcp_diag.c

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/*
* tcp_diag.c Module for monitoring TCP sockets.
*
* Version: $Id: tcp_diag.c,v 1.3 2002/02/01 22:01:04 davem Exp $
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*
* This program 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 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/random.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/time.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/ipv6.h>
#include <net/inet_common.h>
#include <linux/inet.h>
#include <linux/stddef.h>
#include <linux/tcp_diag.h>
struct tcpdiag_entry
{
u32 *saddr;
u32 *daddr;
u16 sport;
u16 dport;
u16 family;
u16 userlocks;
};
static struct sock *tcpnl;
#define TCPDIAG_PUT(skb, attrtype, attrlen) \
({ int rtalen = RTA_LENGTH(attrlen); \
struct rtattr *rta; \
if (skb_tailroom(skb) < RTA_ALIGN(rtalen)) goto nlmsg_failure; \
rta = (void*)__skb_put(skb, RTA_ALIGN(rtalen)); \
rta->rta_type = attrtype; \
rta->rta_len = rtalen; \
RTA_DATA(rta); })
static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
int ext, u32 pid, u32 seq, u16 nlmsg_flags)
{
struct inet_sock *inet = inet_sk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct tcpdiagmsg *r;
struct nlmsghdr *nlh;
struct tcp_info *info = NULL;
struct tcpdiag_meminfo *minfo = NULL;
struct tcpvegas_info *vinfo = NULL;
unsigned char *b = skb->tail;
nlh = NLMSG_PUT(skb, pid, seq, TCPDIAG_GETSOCK, sizeof(*r));
nlh->nlmsg_flags = nlmsg_flags;
r = NLMSG_DATA(nlh);
if (sk->sk_state != TCP_TIME_WAIT) {
if (ext & (1<<(TCPDIAG_MEMINFO-1)))
minfo = TCPDIAG_PUT(skb, TCPDIAG_MEMINFO, sizeof(*minfo));
if (ext & (1<<(TCPDIAG_INFO-1)))
info = TCPDIAG_PUT(skb, TCPDIAG_INFO, sizeof(*info));
if ((tcp_is_westwood(tp) || tcp_is_vegas(tp))
&& (ext & (1<<(TCPDIAG_VEGASINFO-1))))
vinfo = TCPDIAG_PUT(skb, TCPDIAG_VEGASINFO, sizeof(*vinfo));
}
r->tcpdiag_family = sk->sk_family;
r->tcpdiag_state = sk->sk_state;
r->tcpdiag_timer = 0;
r->tcpdiag_retrans = 0;
r->id.tcpdiag_if = sk->sk_bound_dev_if;
r->id.tcpdiag_cookie[0] = (u32)(unsigned long)sk;
r->id.tcpdiag_cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
if (r->tcpdiag_state == TCP_TIME_WAIT) {
struct tcp_tw_bucket *tw = (struct tcp_tw_bucket*)sk;
long tmo = tw->tw_ttd - jiffies;
if (tmo < 0)
tmo = 0;
r->id.tcpdiag_sport = tw->tw_sport;
r->id.tcpdiag_dport = tw->tw_dport;
r->id.tcpdiag_src[0] = tw->tw_rcv_saddr;
r->id.tcpdiag_dst[0] = tw->tw_daddr;
r->tcpdiag_state = tw->tw_substate;
r->tcpdiag_timer = 3;
r->tcpdiag_expires = (tmo*1000+HZ-1)/HZ;
r->tcpdiag_rqueue = 0;
r->tcpdiag_wqueue = 0;
r->tcpdiag_uid = 0;
r->tcpdiag_inode = 0;
#ifdef CONFIG_IP_TCPDIAG_IPV6
if (r->tcpdiag_family == AF_INET6) {
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_src,
&tw->tw_v6_rcv_saddr);
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_dst,
&tw->tw_v6_daddr);
}
#endif
nlh->nlmsg_len = skb->tail - b;
return skb->len;
}
r->id.tcpdiag_sport = inet->sport;
r->id.tcpdiag_dport = inet->dport;
r->id.tcpdiag_src[0] = inet->rcv_saddr;
r->id.tcpdiag_dst[0] = inet->daddr;
#ifdef CONFIG_IP_TCPDIAG_IPV6
if (r->tcpdiag_family == AF_INET6) {
struct ipv6_pinfo *np = inet6_sk(sk);
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_src,
&np->rcv_saddr);
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_dst,
&np->daddr);
}
#endif
#define EXPIRES_IN_MS(tmo) ((tmo-jiffies)*1000+HZ-1)/HZ
if (tp->pending == TCP_TIME_RETRANS) {
r->tcpdiag_timer = 1;
r->tcpdiag_retrans = tp->retransmits;
r->tcpdiag_expires = EXPIRES_IN_MS(tp->timeout);
} else if (tp->pending == TCP_TIME_PROBE0) {
r->tcpdiag_timer = 4;
r->tcpdiag_retrans = tp->probes_out;
r->tcpdiag_expires = EXPIRES_IN_MS(tp->timeout);
} else if (timer_pending(&sk->sk_timer)) {
r->tcpdiag_timer = 2;
r->tcpdiag_retrans = tp->probes_out;
r->tcpdiag_expires = EXPIRES_IN_MS(sk->sk_timer.expires);
} else {
r->tcpdiag_timer = 0;
r->tcpdiag_expires = 0;
}
#undef EXPIRES_IN_MS
r->tcpdiag_rqueue = tp->rcv_nxt - tp->copied_seq;
r->tcpdiag_wqueue = tp->write_seq - tp->snd_una;
r->tcpdiag_uid = sock_i_uid(sk);
r->tcpdiag_inode = sock_i_ino(sk);
if (minfo) {
minfo->tcpdiag_rmem = atomic_read(&sk->sk_rmem_alloc);
minfo->tcpdiag_wmem = sk->sk_wmem_queued;
minfo->tcpdiag_fmem = sk->sk_forward_alloc;
minfo->tcpdiag_tmem = atomic_read(&sk->sk_wmem_alloc);
}
if (info)
tcp_get_info(sk, info);
if (vinfo) {
if (tcp_is_vegas(tp)) {
vinfo->tcpv_enabled = tp->vegas.doing_vegas_now;
vinfo->tcpv_rttcnt = tp->vegas.cntRTT;
vinfo->tcpv_rtt = jiffies_to_usecs(tp->vegas.baseRTT);
vinfo->tcpv_minrtt = jiffies_to_usecs(tp->vegas.minRTT);
} else {
vinfo->tcpv_enabled = 0;
vinfo->tcpv_rttcnt = 0;
vinfo->tcpv_rtt = jiffies_to_usecs(tp->westwood.rtt);
vinfo->tcpv_minrtt = jiffies_to_usecs(tp->westwood.rtt_min);
}
}
nlh->nlmsg_len = skb->tail - b;
return skb->len;
nlmsg_failure:
skb_trim(skb, b - skb->data);
return -1;
}
extern struct sock *tcp_v4_lookup(u32 saddr, u16 sport, u32 daddr, u16 dport,
int dif);
#ifdef CONFIG_IP_TCPDIAG_IPV6
extern struct sock *tcp_v6_lookup(struct in6_addr *saddr, u16 sport,
struct in6_addr *daddr, u16 dport,
int dif);
#else
static inline struct sock *tcp_v6_lookup(struct in6_addr *saddr, u16 sport,
struct in6_addr *daddr, u16 dport,
int dif)
{
return NULL;
}
#endif
static int tcpdiag_get_exact(struct sk_buff *in_skb, const struct nlmsghdr *nlh)
{
int err;
struct sock *sk;
struct tcpdiagreq *req = NLMSG_DATA(nlh);
struct sk_buff *rep;
if (req->tcpdiag_family == AF_INET) {
sk = tcp_v4_lookup(req->id.tcpdiag_dst[0], req->id.tcpdiag_dport,
req->id.tcpdiag_src[0], req->id.tcpdiag_sport,
req->id.tcpdiag_if);
}
#ifdef CONFIG_IP_TCPDIAG_IPV6
else if (req->tcpdiag_family == AF_INET6) {
sk = tcp_v6_lookup((struct in6_addr*)req->id.tcpdiag_dst, req->id.tcpdiag_dport,
(struct in6_addr*)req->id.tcpdiag_src, req->id.tcpdiag_sport,
req->id.tcpdiag_if);
}
#endif
else {
return -EINVAL;
}
if (sk == NULL)
return -ENOENT;
err = -ESTALE;
if ((req->id.tcpdiag_cookie[0] != TCPDIAG_NOCOOKIE ||
req->id.tcpdiag_cookie[1] != TCPDIAG_NOCOOKIE) &&
((u32)(unsigned long)sk != req->id.tcpdiag_cookie[0] ||
(u32)((((unsigned long)sk) >> 31) >> 1) != req->id.tcpdiag_cookie[1]))
goto out;
err = -ENOMEM;
rep = alloc_skb(NLMSG_SPACE(sizeof(struct tcpdiagmsg)+
sizeof(struct tcpdiag_meminfo)+
sizeof(struct tcp_info)+64), GFP_KERNEL);
if (!rep)
goto out;
if (tcpdiag_fill(rep, sk, req->tcpdiag_ext,
NETLINK_CB(in_skb).pid,
nlh->nlmsg_seq, 0) <= 0)
BUG();
err = netlink_unicast(tcpnl, rep, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
if (err > 0)
err = 0;
out:
if (sk) {
if (sk->sk_state == TCP_TIME_WAIT)
tcp_tw_put((struct tcp_tw_bucket*)sk);
else
sock_put(sk);
}
return err;
}
static int bitstring_match(const u32 *a1, const u32 *a2, int bits)
{
int words = bits >> 5;
bits &= 0x1f;
if (words) {
if (memcmp(a1, a2, words << 2))
return 0;
}
if (bits) {
__u32 w1, w2;
__u32 mask;
w1 = a1[words];
w2 = a2[words];
mask = htonl((0xffffffff) << (32 - bits));
if ((w1 ^ w2) & mask)
return 0;
}
return 1;
}
static int tcpdiag_bc_run(const void *bc, int len,
const struct tcpdiag_entry *entry)
{
while (len > 0) {
int yes = 1;
const struct tcpdiag_bc_op *op = bc;
switch (op->code) {
case TCPDIAG_BC_NOP:
break;
case TCPDIAG_BC_JMP:
yes = 0;
break;
case TCPDIAG_BC_S_GE:
yes = entry->sport >= op[1].no;
break;
case TCPDIAG_BC_S_LE:
yes = entry->dport <= op[1].no;
break;
case TCPDIAG_BC_D_GE:
yes = entry->dport >= op[1].no;
break;
case TCPDIAG_BC_D_LE:
yes = entry->dport <= op[1].no;
break;
case TCPDIAG_BC_AUTO:
yes = !(entry->userlocks & SOCK_BINDPORT_LOCK);
break;
case TCPDIAG_BC_S_COND:
case TCPDIAG_BC_D_COND:
{
struct tcpdiag_hostcond *cond = (struct tcpdiag_hostcond*)(op+1);
u32 *addr;
if (cond->port != -1 &&
cond->port != (op->code == TCPDIAG_BC_S_COND ?
entry->sport : entry->dport)) {
yes = 0;
break;
}
if (cond->prefix_len == 0)
break;
if (op->code == TCPDIAG_BC_S_COND)
addr = entry->saddr;
else
addr = entry->daddr;
if (bitstring_match(addr, cond->addr, cond->prefix_len))
break;
if (entry->family == AF_INET6 &&
cond->family == AF_INET) {
if (addr[0] == 0 && addr[1] == 0 &&
addr[2] == htonl(0xffff) &&
bitstring_match(addr+3, cond->addr, cond->prefix_len))
break;
}
yes = 0;
break;
}
}
if (yes) {
len -= op->yes;
bc += op->yes;
} else {
len -= op->no;
bc += op->no;
}
}
return (len == 0);
}
static int valid_cc(const void *bc, int len, int cc)
{
while (len >= 0) {
const struct tcpdiag_bc_op *op = bc;
if (cc > len)
return 0;
if (cc == len)
return 1;
if (op->yes < 4)
return 0;
len -= op->yes;
bc += op->yes;
}
return 0;
}
static int tcpdiag_bc_audit(const void *bytecode, int bytecode_len)
{
const unsigned char *bc = bytecode;
int len = bytecode_len;
while (len > 0) {
struct tcpdiag_bc_op *op = (struct tcpdiag_bc_op*)bc;
//printk("BC: %d %d %d {%d} / %d\n", op->code, op->yes, op->no, op[1].no, len);
switch (op->code) {
case TCPDIAG_BC_AUTO:
case TCPDIAG_BC_S_COND:
case TCPDIAG_BC_D_COND:
case TCPDIAG_BC_S_GE:
case TCPDIAG_BC_S_LE:
case TCPDIAG_BC_D_GE:
case TCPDIAG_BC_D_LE:
if (op->yes < 4 || op->yes > len+4)
return -EINVAL;
case TCPDIAG_BC_JMP:
if (op->no < 4 || op->no > len+4)
return -EINVAL;
if (op->no < len &&
!valid_cc(bytecode, bytecode_len, len-op->no))
return -EINVAL;
break;
case TCPDIAG_BC_NOP:
if (op->yes < 4 || op->yes > len+4)
return -EINVAL;
break;
default:
return -EINVAL;
}
bc += op->yes;
len -= op->yes;
}
return len == 0 ? 0 : -EINVAL;
}
static int tcpdiag_dump_sock(struct sk_buff *skb, struct sock *sk,
struct netlink_callback *cb)
{
struct tcpdiagreq *r = NLMSG_DATA(cb->nlh);
if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
struct tcpdiag_entry entry;
struct rtattr *bc = (struct rtattr *)(r + 1);
struct inet_sock *inet = inet_sk(sk);
entry.family = sk->sk_family;
#ifdef CONFIG_IP_TCPDIAG_IPV6
if (entry.family == AF_INET6) {
struct ipv6_pinfo *np = inet6_sk(sk);
entry.saddr = np->rcv_saddr.s6_addr32;
entry.daddr = np->daddr.s6_addr32;
} else
#endif
{
entry.saddr = &inet->rcv_saddr;
entry.daddr = &inet->daddr;
}
entry.sport = inet->num;
entry.dport = ntohs(inet->dport);
entry.userlocks = sk->sk_userlocks;
if (!tcpdiag_bc_run(RTA_DATA(bc), RTA_PAYLOAD(bc), &entry))
return 0;
}
return tcpdiag_fill(skb, sk, r->tcpdiag_ext, NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, NLM_F_MULTI);
}
static int tcpdiag_fill_req(struct sk_buff *skb, struct sock *sk,
struct request_sock *req,
u32 pid, u32 seq)
{
const struct inet_request_sock *ireq = inet_rsk(req);
struct inet_sock *inet = inet_sk(sk);
unsigned char *b = skb->tail;
struct tcpdiagmsg *r;
struct nlmsghdr *nlh;
long tmo;
nlh = NLMSG_PUT(skb, pid, seq, TCPDIAG_GETSOCK, sizeof(*r));
nlh->nlmsg_flags = NLM_F_MULTI;
r = NLMSG_DATA(nlh);
r->tcpdiag_family = sk->sk_family;
r->tcpdiag_state = TCP_SYN_RECV;
r->tcpdiag_timer = 1;
r->tcpdiag_retrans = req->retrans;
r->id.tcpdiag_if = sk->sk_bound_dev_if;
r->id.tcpdiag_cookie[0] = (u32)(unsigned long)req;
r->id.tcpdiag_cookie[1] = (u32)(((unsigned long)req >> 31) >> 1);
tmo = req->expires - jiffies;
if (tmo < 0)
tmo = 0;
r->id.tcpdiag_sport = inet->sport;
r->id.tcpdiag_dport = ireq->rmt_port;
r->id.tcpdiag_src[0] = ireq->loc_addr;
r->id.tcpdiag_dst[0] = ireq->rmt_addr;
r->tcpdiag_expires = jiffies_to_msecs(tmo),
r->tcpdiag_rqueue = 0;
r->tcpdiag_wqueue = 0;
r->tcpdiag_uid = sock_i_uid(sk);
r->tcpdiag_inode = 0;
#ifdef CONFIG_IP_TCPDIAG_IPV6
if (r->tcpdiag_family == AF_INET6) {
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_src,
&tcp6_rsk(req)->loc_addr);
ipv6_addr_copy((struct in6_addr *)r->id.tcpdiag_dst,
&tcp6_rsk(req)->rmt_addr);
}
#endif
nlh->nlmsg_len = skb->tail - b;
return skb->len;
nlmsg_failure:
skb_trim(skb, b - skb->data);
return -1;
}
static int tcpdiag_dump_reqs(struct sk_buff *skb, struct sock *sk,
struct netlink_callback *cb)
{
struct tcpdiag_entry entry;
struct tcpdiagreq *r = NLMSG_DATA(cb->nlh);
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_listen_opt *lopt;
struct rtattr *bc = NULL;
struct inet_sock *inet = inet_sk(sk);
int j, s_j;
int reqnum, s_reqnum;
int err = 0;
s_j = cb->args[3];
s_reqnum = cb->args[4];
if (s_j > 0)
s_j--;
entry.family = sk->sk_family;
read_lock_bh(&tp->syn_wait_lock);
lopt = tp->listen_opt;
if (!lopt || !lopt->qlen)
goto out;
if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
bc = (struct rtattr *)(r + 1);
entry.sport = inet->num;
entry.userlocks = sk->sk_userlocks;
}
for (j = s_j; j < TCP_SYNQ_HSIZE; j++) {
struct request_sock *req, *head = lopt->syn_table[j];
reqnum = 0;
for (req = head; req; reqnum++, req = req->dl_next) {
struct inet_request_sock *ireq = inet_rsk(req);
if (reqnum < s_reqnum)
continue;
if (r->id.tcpdiag_dport != ireq->rmt_port &&
r->id.tcpdiag_dport)
continue;
if (bc) {
entry.saddr =
#ifdef CONFIG_IP_TCPDIAG_IPV6
(entry.family == AF_INET6) ?
tcp6_rsk(req)->loc_addr.s6_addr32 :
#endif
&ireq->loc_addr;
entry.daddr =
#ifdef CONFIG_IP_TCPDIAG_IPV6
(entry.family == AF_INET6) ?
tcp6_rsk(req)->rmt_addr.s6_addr32 :
#endif
&ireq->rmt_addr;
entry.dport = ntohs(ireq->rmt_port);
if (!tcpdiag_bc_run(RTA_DATA(bc),
RTA_PAYLOAD(bc), &entry))
continue;
}
err = tcpdiag_fill_req(skb, sk, req,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq);
if (err < 0) {
cb->args[3] = j + 1;
cb->args[4] = reqnum;
goto out;
}
}
s_reqnum = 0;
}
out:
read_unlock_bh(&tp->syn_wait_lock);
return err;
}
static int tcpdiag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
int i, num;
int s_i, s_num;
struct tcpdiagreq *r = NLMSG_DATA(cb->nlh);
s_i = cb->args[1];
s_num = num = cb->args[2];
if (cb->args[0] == 0) {
if (!(r->tcpdiag_states&(TCPF_LISTEN|TCPF_SYN_RECV)))
goto skip_listen_ht;
tcp_listen_lock();
for (i = s_i; i < TCP_LHTABLE_SIZE; i++) {
struct sock *sk;
struct hlist_node *node;
num = 0;
sk_for_each(sk, node, &tcp_listening_hash[i]) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num) {
num++;
continue;
}
if (r->id.tcpdiag_sport != inet->sport &&
r->id.tcpdiag_sport)
goto next_listen;
if (!(r->tcpdiag_states&TCPF_LISTEN) ||
r->id.tcpdiag_dport ||
cb->args[3] > 0)
goto syn_recv;
if (tcpdiag_dump_sock(skb, sk, cb) < 0) {
tcp_listen_unlock();
goto done;
}
syn_recv:
if (!(r->tcpdiag_states&TCPF_SYN_RECV))
goto next_listen;
if (tcpdiag_dump_reqs(skb, sk, cb) < 0) {
tcp_listen_unlock();
goto done;
}
next_listen:
cb->args[3] = 0;
cb->args[4] = 0;
++num;
}
s_num = 0;
cb->args[3] = 0;
cb->args[4] = 0;
}
tcp_listen_unlock();
skip_listen_ht:
cb->args[0] = 1;
s_i = num = s_num = 0;
}
if (!(r->tcpdiag_states&~(TCPF_LISTEN|TCPF_SYN_RECV)))
return skb->len;
for (i = s_i; i < tcp_ehash_size; i++) {
struct tcp_ehash_bucket *head = &tcp_ehash[i];
struct sock *sk;
struct hlist_node *node;
if (i > s_i)
s_num = 0;
read_lock_bh(&head->lock);
num = 0;
sk_for_each(sk, node, &head->chain) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num)
goto next_normal;
if (!(r->tcpdiag_states & (1 << sk->sk_state)))
goto next_normal;
if (r->id.tcpdiag_sport != inet->sport &&
r->id.tcpdiag_sport)
goto next_normal;
if (r->id.tcpdiag_dport != inet->dport && r->id.tcpdiag_dport)
goto next_normal;
if (tcpdiag_dump_sock(skb, sk, cb) < 0) {
read_unlock_bh(&head->lock);
goto done;
}
next_normal:
++num;
}
if (r->tcpdiag_states&TCPF_TIME_WAIT) {
sk_for_each(sk, node,
&tcp_ehash[i + tcp_ehash_size].chain) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num)
goto next_dying;
if (r->id.tcpdiag_sport != inet->sport &&
r->id.tcpdiag_sport)
goto next_dying;
if (r->id.tcpdiag_dport != inet->dport &&
r->id.tcpdiag_dport)
goto next_dying;
if (tcpdiag_dump_sock(skb, sk, cb) < 0) {
read_unlock_bh(&head->lock);
goto done;
}
next_dying:
++num;
}
}
read_unlock_bh(&head->lock);
}
done:
cb->args[1] = i;
cb->args[2] = num;
return skb->len;
}
static int tcpdiag_dump_done(struct netlink_callback *cb)
{
return 0;
}
static __inline__ int
tcpdiag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
if (!(nlh->nlmsg_flags&NLM_F_REQUEST))
return 0;
if (nlh->nlmsg_type != TCPDIAG_GETSOCK)
goto err_inval;
if (NLMSG_LENGTH(sizeof(struct tcpdiagreq)) > skb->len)
goto err_inval;
if (nlh->nlmsg_flags&NLM_F_DUMP) {
if (nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(struct tcpdiagreq))) {
struct rtattr *rta = (struct rtattr*)(NLMSG_DATA(nlh) + sizeof(struct tcpdiagreq));
if (rta->rta_type != TCPDIAG_REQ_BYTECODE ||
rta->rta_len < 8 ||
rta->rta_len > nlh->nlmsg_len - NLMSG_SPACE(sizeof(struct tcpdiagreq)))
goto err_inval;
if (tcpdiag_bc_audit(RTA_DATA(rta), RTA_PAYLOAD(rta)))
goto err_inval;
}
return netlink_dump_start(tcpnl, skb, nlh,
tcpdiag_dump,
tcpdiag_dump_done);
} else {
return tcpdiag_get_exact(skb, nlh);
}
err_inval:
return -EINVAL;
}
static inline void tcpdiag_rcv_skb(struct sk_buff *skb)
{
int err;
struct nlmsghdr * nlh;
if (skb->len >= NLMSG_SPACE(0)) {
nlh = (struct nlmsghdr *)skb->data;
if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
return;
err = tcpdiag_rcv_msg(skb, nlh);
if (err || nlh->nlmsg_flags & NLM_F_ACK)
netlink_ack(skb, nlh, err);
}
}
static void tcpdiag_rcv(struct sock *sk, int len)
{
struct sk_buff *skb;
[NETLINK]: Synchronous message processing. Let's recap the problem. The current asynchronous netlink kernel message processing is vulnerable to these attacks: 1) Hit and run: Attacker sends one or more messages and then exits before they're processed. This may confuse/disable the next netlink user that gets the netlink address of the attacker since it may receive the responses to the attacker's messages. Proposed solutions: a) Synchronous processing. b) Stream mode socket. c) Restrict/prohibit binding. 2) Starvation: Because various netlink rcv functions were written to not return until all messages have been processed on a socket, it is possible for these functions to execute for an arbitrarily long period of time. If this is successfully exploited it could also be used to hold rtnl forever. Proposed solutions: a) Synchronous processing. b) Stream mode socket. Firstly let's cross off solution c). It only solves the first problem and it has user-visible impacts. In particular, it'll break user space applications that expect to bind or communicate with specific netlink addresses (pid's). So we're left with a choice of synchronous processing versus SOCK_STREAM for netlink. For the moment I'm sticking with the synchronous approach as suggested by Alexey since it's simpler and I'd rather spend my time working on other things. However, it does have a number of deficiencies compared to the stream mode solution: 1) User-space to user-space netlink communication is still vulnerable. 2) Inefficient use of resources. This is especially true for rtnetlink since the lock is shared with other users such as networking drivers. The latter could hold the rtnl while communicating with hardware which causes the rtnetlink user to wait when it could be doing other things. 3) It is still possible to DoS all netlink users by flooding the kernel netlink receive queue. The attacker simply fills the receive socket with a single netlink message that fills up the entire queue. The attacker then continues to call sendmsg with the same message in a loop. Point 3) can be countered by retransmissions in user-space code, however it is pretty messy. In light of these problems (in particular, point 3), we should implement stream mode netlink at some point. In the mean time, here is a patch that implements synchronous processing. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 23:55:09 +02:00
unsigned int qlen = skb_queue_len(&sk->sk_receive_queue);
[NETLINK]: Synchronous message processing. Let's recap the problem. The current asynchronous netlink kernel message processing is vulnerable to these attacks: 1) Hit and run: Attacker sends one or more messages and then exits before they're processed. This may confuse/disable the next netlink user that gets the netlink address of the attacker since it may receive the responses to the attacker's messages. Proposed solutions: a) Synchronous processing. b) Stream mode socket. c) Restrict/prohibit binding. 2) Starvation: Because various netlink rcv functions were written to not return until all messages have been processed on a socket, it is possible for these functions to execute for an arbitrarily long period of time. If this is successfully exploited it could also be used to hold rtnl forever. Proposed solutions: a) Synchronous processing. b) Stream mode socket. Firstly let's cross off solution c). It only solves the first problem and it has user-visible impacts. In particular, it'll break user space applications that expect to bind or communicate with specific netlink addresses (pid's). So we're left with a choice of synchronous processing versus SOCK_STREAM for netlink. For the moment I'm sticking with the synchronous approach as suggested by Alexey since it's simpler and I'd rather spend my time working on other things. However, it does have a number of deficiencies compared to the stream mode solution: 1) User-space to user-space netlink communication is still vulnerable. 2) Inefficient use of resources. This is especially true for rtnetlink since the lock is shared with other users such as networking drivers. The latter could hold the rtnl while communicating with hardware which causes the rtnetlink user to wait when it could be doing other things. 3) It is still possible to DoS all netlink users by flooding the kernel netlink receive queue. The attacker simply fills the receive socket with a single netlink message that fills up the entire queue. The attacker then continues to call sendmsg with the same message in a loop. Point 3) can be countered by retransmissions in user-space code, however it is pretty messy. In light of these problems (in particular, point 3), we should implement stream mode netlink at some point. In the mean time, here is a patch that implements synchronous processing. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-05-03 23:55:09 +02:00
while (qlen-- && (skb = skb_dequeue(&sk->sk_receive_queue))) {
tcpdiag_rcv_skb(skb);
kfree_skb(skb);
}
}
static int __init tcpdiag_init(void)
{
tcpnl = netlink_kernel_create(NETLINK_TCPDIAG, tcpdiag_rcv);
if (tcpnl == NULL)
return -ENOMEM;
return 0;
}
static void __exit tcpdiag_exit(void)
{
sock_release(tcpnl->sk_socket);
}
module_init(tcpdiag_init);
module_exit(tcpdiag_exit);
MODULE_LICENSE("GPL");