linux/net/ipv4/inet_diag.c

869 lines
20 KiB
C
Raw Normal View History

/*
* inet_diag.c Module for monitoring INET transport protocols sockets.
*
* Version: $Id: inet_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 <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#include <net/inet_timewait_sock.h>
#include <net/inet6_hashtables.h>
#include <linux/inet.h>
#include <linux/stddef.h>
#include <linux/inet_diag.h>
static const struct inet_diag_handler **inet_diag_table;
struct inet_diag_entry {
u32 *saddr;
u32 *daddr;
u16 sport;
u16 dport;
u16 family;
u16 userlocks;
};
static struct sock *idiagnl;
#define INET_DIAG_PUT(skb, attrtype, attrlen) \
RTA_DATA(__RTA_PUT(skb, attrtype, attrlen))
static int inet_diag_fill(struct sk_buff *skb, struct sock *sk,
int ext, u32 pid, u32 seq, u16 nlmsg_flags,
const struct nlmsghdr *unlh)
{
const struct inet_sock *inet = inet_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
struct inet_diag_msg *r;
struct nlmsghdr *nlh;
void *info = NULL;
struct inet_diag_meminfo *minfo = NULL;
unsigned char *b = skb->tail;
const struct inet_diag_handler *handler;
handler = inet_diag_table[unlh->nlmsg_type];
BUG_ON(handler == NULL);
nlh = NLMSG_PUT(skb, pid, seq, unlh->nlmsg_type, sizeof(*r));
nlh->nlmsg_flags = nlmsg_flags;
r = NLMSG_DATA(nlh);
if (sk->sk_state != TCP_TIME_WAIT) {
if (ext & (1 << (INET_DIAG_MEMINFO - 1)))
minfo = INET_DIAG_PUT(skb, INET_DIAG_MEMINFO,
sizeof(*minfo));
if (ext & (1 << (INET_DIAG_INFO - 1)))
info = INET_DIAG_PUT(skb, INET_DIAG_INFO,
handler->idiag_info_size);
if ((ext & (1 << (INET_DIAG_CONG - 1))) && icsk->icsk_ca_ops) {
size_t len = strlen(icsk->icsk_ca_ops->name);
strcpy(INET_DIAG_PUT(skb, INET_DIAG_CONG, len + 1),
icsk->icsk_ca_ops->name);
}
}
r->idiag_family = sk->sk_family;
r->idiag_state = sk->sk_state;
r->idiag_timer = 0;
r->idiag_retrans = 0;
r->id.idiag_if = sk->sk_bound_dev_if;
r->id.idiag_cookie[0] = (u32)(unsigned long)sk;
r->id.idiag_cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
if (r->idiag_state == TCP_TIME_WAIT) {
const struct inet_timewait_sock *tw = inet_twsk(sk);
long tmo = tw->tw_ttd - jiffies;
if (tmo < 0)
tmo = 0;
r->id.idiag_sport = tw->tw_sport;
r->id.idiag_dport = tw->tw_dport;
r->id.idiag_src[0] = tw->tw_rcv_saddr;
r->id.idiag_dst[0] = tw->tw_daddr;
r->idiag_state = tw->tw_substate;
r->idiag_timer = 3;
r->idiag_expires = (tmo * 1000 + HZ - 1) / HZ;
r->idiag_rqueue = 0;
r->idiag_wqueue = 0;
r->idiag_uid = 0;
r->idiag_inode = 0;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
if (r->idiag_family == AF_INET6) {
const struct tcp6_timewait_sock *tcp6tw = tcp6_twsk(sk);
ipv6_addr_copy((struct in6_addr *)r->id.idiag_src,
&tcp6tw->tw_v6_rcv_saddr);
ipv6_addr_copy((struct in6_addr *)r->id.idiag_dst,
&tcp6tw->tw_v6_daddr);
}
#endif
nlh->nlmsg_len = skb->tail - b;
return skb->len;
}
r->id.idiag_sport = inet->sport;
r->id.idiag_dport = inet->dport;
r->id.idiag_src[0] = inet->rcv_saddr;
r->id.idiag_dst[0] = inet->daddr;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
if (r->idiag_family == AF_INET6) {
struct ipv6_pinfo *np = inet6_sk(sk);
ipv6_addr_copy((struct in6_addr *)r->id.idiag_src,
&np->rcv_saddr);
ipv6_addr_copy((struct in6_addr *)r->id.idiag_dst,
&np->daddr);
}
#endif
#define EXPIRES_IN_MS(tmo) ((tmo - jiffies) * 1000 + HZ - 1) / HZ
if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
r->idiag_timer = 1;
r->idiag_retrans = icsk->icsk_retransmits;
r->idiag_expires = EXPIRES_IN_MS(icsk->icsk_timeout);
} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
r->idiag_timer = 4;
r->idiag_retrans = icsk->icsk_probes_out;
r->idiag_expires = EXPIRES_IN_MS(icsk->icsk_timeout);
} else if (timer_pending(&sk->sk_timer)) {
r->idiag_timer = 2;
r->idiag_retrans = icsk->icsk_probes_out;
r->idiag_expires = EXPIRES_IN_MS(sk->sk_timer.expires);
} else {
r->idiag_timer = 0;
r->idiag_expires = 0;
}
#undef EXPIRES_IN_MS
r->idiag_uid = sock_i_uid(sk);
r->idiag_inode = sock_i_ino(sk);
if (minfo) {
minfo->idiag_rmem = atomic_read(&sk->sk_rmem_alloc);
minfo->idiag_wmem = sk->sk_wmem_queued;
minfo->idiag_fmem = sk->sk_forward_alloc;
minfo->idiag_tmem = atomic_read(&sk->sk_wmem_alloc);
}
handler->idiag_get_info(sk, r, info);
if (sk->sk_state < TCP_TIME_WAIT &&
icsk->icsk_ca_ops && icsk->icsk_ca_ops->get_info)
icsk->icsk_ca_ops->get_info(sk, ext, skb);
nlh->nlmsg_len = skb->tail - b;
return skb->len;
rtattr_failure:
nlmsg_failure:
skb_trim(skb, b - skb->data);
return -1;
}
static int inet_diag_get_exact(struct sk_buff *in_skb, const struct nlmsghdr *nlh)
{
int err;
struct sock *sk;
struct inet_diag_req *req = NLMSG_DATA(nlh);
struct sk_buff *rep;
struct inet_hashinfo *hashinfo;
const struct inet_diag_handler *handler;
handler = inet_diag_table[nlh->nlmsg_type];
BUG_ON(handler == NULL);
hashinfo = handler->idiag_hashinfo;
if (req->idiag_family == AF_INET) {
sk = inet_lookup(hashinfo, req->id.idiag_dst[0],
req->id.idiag_dport, req->id.idiag_src[0],
req->id.idiag_sport, req->id.idiag_if);
}
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
else if (req->idiag_family == AF_INET6) {
sk = inet6_lookup(hashinfo,
(struct in6_addr *)req->id.idiag_dst,
req->id.idiag_dport,
(struct in6_addr *)req->id.idiag_src,
req->id.idiag_sport,
req->id.idiag_if);
}
#endif
else {
return -EINVAL;
}
if (sk == NULL)
return -ENOENT;
err = -ESTALE;
if ((req->id.idiag_cookie[0] != INET_DIAG_NOCOOKIE ||
req->id.idiag_cookie[1] != INET_DIAG_NOCOOKIE) &&
((u32)(unsigned long)sk != req->id.idiag_cookie[0] ||
(u32)((((unsigned long)sk) >> 31) >> 1) != req->id.idiag_cookie[1]))
goto out;
err = -ENOMEM;
rep = alloc_skb(NLMSG_SPACE((sizeof(struct inet_diag_msg) +
sizeof(struct inet_diag_meminfo) +
handler->idiag_info_size + 64)),
GFP_KERNEL);
if (!rep)
goto out;
if (inet_diag_fill(rep, sk, req->idiag_ext,
NETLINK_CB(in_skb).pid,
nlh->nlmsg_seq, 0, nlh) <= 0)
BUG();
err = netlink_unicast(idiagnl, rep, NETLINK_CB(in_skb).pid,
MSG_DONTWAIT);
if (err > 0)
err = 0;
out:
if (sk) {
if (sk->sk_state == TCP_TIME_WAIT)
inet_twsk_put((struct inet_timewait_sock *)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 inet_diag_bc_run(const void *bc, int len,
const struct inet_diag_entry *entry)
{
while (len > 0) {
int yes = 1;
const struct inet_diag_bc_op *op = bc;
switch (op->code) {
case INET_DIAG_BC_NOP:
break;
case INET_DIAG_BC_JMP:
yes = 0;
break;
case INET_DIAG_BC_S_GE:
yes = entry->sport >= op[1].no;
break;
case INET_DIAG_BC_S_LE:
yes = entry->dport <= op[1].no;
break;
case INET_DIAG_BC_D_GE:
yes = entry->dport >= op[1].no;
break;
case INET_DIAG_BC_D_LE:
yes = entry->dport <= op[1].no;
break;
case INET_DIAG_BC_AUTO:
yes = !(entry->userlocks & SOCK_BINDPORT_LOCK);
break;
case INET_DIAG_BC_S_COND:
case INET_DIAG_BC_D_COND: {
struct inet_diag_hostcond *cond;
u32 *addr;
cond = (struct inet_diag_hostcond *)(op + 1);
if (cond->port != -1 &&
cond->port != (op->code == INET_DIAG_BC_S_COND ?
entry->sport : entry->dport)) {
yes = 0;
break;
}
if (cond->prefix_len == 0)
break;
if (op->code == INET_DIAG_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 inet_diag_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 inet_diag_bc_audit(const void *bytecode, int bytecode_len)
{
const unsigned char *bc = bytecode;
int len = bytecode_len;
while (len > 0) {
struct inet_diag_bc_op *op = (struct inet_diag_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 INET_DIAG_BC_AUTO:
case INET_DIAG_BC_S_COND:
case INET_DIAG_BC_D_COND:
case INET_DIAG_BC_S_GE:
case INET_DIAG_BC_S_LE:
case INET_DIAG_BC_D_GE:
case INET_DIAG_BC_D_LE:
if (op->yes < 4 || op->yes > len + 4)
return -EINVAL;
case INET_DIAG_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 INET_DIAG_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 inet_diag_dump_sock(struct sk_buff *skb, struct sock *sk,
struct netlink_callback *cb)
{
struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
struct inet_diag_entry entry;
struct rtattr *bc = (struct rtattr *)(r + 1);
struct inet_sock *inet = inet_sk(sk);
entry.family = sk->sk_family;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
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 (!inet_diag_bc_run(RTA_DATA(bc), RTA_PAYLOAD(bc), &entry))
return 0;
}
return inet_diag_fill(skb, sk, r->idiag_ext, NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
}
static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk,
struct request_sock *req,
u32 pid, u32 seq,
const struct nlmsghdr *unlh)
{
const struct inet_request_sock *ireq = inet_rsk(req);
struct inet_sock *inet = inet_sk(sk);
unsigned char *b = skb->tail;
struct inet_diag_msg *r;
struct nlmsghdr *nlh;
long tmo;
nlh = NLMSG_PUT(skb, pid, seq, unlh->nlmsg_type, sizeof(*r));
nlh->nlmsg_flags = NLM_F_MULTI;
r = NLMSG_DATA(nlh);
r->idiag_family = sk->sk_family;
r->idiag_state = TCP_SYN_RECV;
r->idiag_timer = 1;
r->idiag_retrans = req->retrans;
r->id.idiag_if = sk->sk_bound_dev_if;
r->id.idiag_cookie[0] = (u32)(unsigned long)req;
r->id.idiag_cookie[1] = (u32)(((unsigned long)req >> 31) >> 1);
tmo = req->expires - jiffies;
if (tmo < 0)
tmo = 0;
r->id.idiag_sport = inet->sport;
r->id.idiag_dport = ireq->rmt_port;
r->id.idiag_src[0] = ireq->loc_addr;
r->id.idiag_dst[0] = ireq->rmt_addr;
r->idiag_expires = jiffies_to_msecs(tmo);
r->idiag_rqueue = 0;
r->idiag_wqueue = 0;
r->idiag_uid = sock_i_uid(sk);
r->idiag_inode = 0;
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
if (r->idiag_family == AF_INET6) {
ipv6_addr_copy((struct in6_addr *)r->id.idiag_src,
&tcp6_rsk(req)->loc_addr);
ipv6_addr_copy((struct in6_addr *)r->id.idiag_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 inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
struct netlink_callback *cb)
{
struct inet_diag_entry entry;
struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
struct inet_connection_sock *icsk = inet_csk(sk);
struct listen_sock *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(&icsk->icsk_accept_queue.syn_wait_lock);
lopt = icsk->icsk_accept_queue.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 < lopt->nr_table_entries; 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.idiag_dport != ireq->rmt_port &&
r->id.idiag_dport)
continue;
if (bc) {
entry.saddr =
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
(entry.family == AF_INET6) ?
tcp6_rsk(req)->loc_addr.s6_addr32 :
#endif
&ireq->loc_addr;
entry.daddr =
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
(entry.family == AF_INET6) ?
tcp6_rsk(req)->rmt_addr.s6_addr32 :
#endif
&ireq->rmt_addr;
entry.dport = ntohs(ireq->rmt_port);
if (!inet_diag_bc_run(RTA_DATA(bc),
RTA_PAYLOAD(bc), &entry))
continue;
}
err = inet_diag_fill_req(skb, sk, req,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, cb->nlh);
if (err < 0) {
cb->args[3] = j + 1;
cb->args[4] = reqnum;
goto out;
}
}
s_reqnum = 0;
}
out:
read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
return err;
}
static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
int i, num;
int s_i, s_num;
struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
const struct inet_diag_handler *handler;
struct inet_hashinfo *hashinfo;
handler = inet_diag_table[cb->nlh->nlmsg_type];
BUG_ON(handler == NULL);
hashinfo = handler->idiag_hashinfo;
s_i = cb->args[1];
s_num = num = cb->args[2];
if (cb->args[0] == 0) {
if (!(r->idiag_states & (TCPF_LISTEN | TCPF_SYN_RECV)))
goto skip_listen_ht;
inet_listen_lock(hashinfo);
for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
struct sock *sk;
struct hlist_node *node;
num = 0;
sk_for_each(sk, node, &hashinfo->listening_hash[i]) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num) {
num++;
continue;
}
if (r->id.idiag_sport != inet->sport &&
r->id.idiag_sport)
goto next_listen;
if (!(r->idiag_states & TCPF_LISTEN) ||
r->id.idiag_dport ||
cb->args[3] > 0)
goto syn_recv;
if (inet_diag_dump_sock(skb, sk, cb) < 0) {
inet_listen_unlock(hashinfo);
goto done;
}
syn_recv:
if (!(r->idiag_states & TCPF_SYN_RECV))
goto next_listen;
if (inet_diag_dump_reqs(skb, sk, cb) < 0) {
inet_listen_unlock(hashinfo);
goto done;
}
next_listen:
cb->args[3] = 0;
cb->args[4] = 0;
++num;
}
s_num = 0;
cb->args[3] = 0;
cb->args[4] = 0;
}
inet_listen_unlock(hashinfo);
skip_listen_ht:
cb->args[0] = 1;
s_i = num = s_num = 0;
}
if (!(r->idiag_states & ~(TCPF_LISTEN | TCPF_SYN_RECV)))
return skb->len;
for (i = s_i; i < hashinfo->ehash_size; i++) {
struct inet_ehash_bucket *head = &hashinfo->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->idiag_states & (1 << sk->sk_state)))
goto next_normal;
if (r->id.idiag_sport != inet->sport &&
r->id.idiag_sport)
goto next_normal;
if (r->id.idiag_dport != inet->dport && r->id.idiag_dport)
goto next_normal;
if (inet_diag_dump_sock(skb, sk, cb) < 0) {
read_unlock_bh(&head->lock);
goto done;
}
next_normal:
++num;
}
if (r->idiag_states & TCPF_TIME_WAIT) {
sk_for_each(sk, node,
&hashinfo->ehash[i + hashinfo->ehash_size].chain) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num)
goto next_dying;
if (r->id.idiag_sport != inet->sport &&
r->id.idiag_sport)
goto next_dying;
if (r->id.idiag_dport != inet->dport &&
r->id.idiag_dport)
goto next_dying;
if (inet_diag_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 inet_diag_dump_done(struct netlink_callback *cb)
{
return 0;
}
static __inline__ int
inet_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
if (!(nlh->nlmsg_flags&NLM_F_REQUEST))
return 0;
if (nlh->nlmsg_type >= INET_DIAG_GETSOCK_MAX)
goto err_inval;
if (inet_diag_table[nlh->nlmsg_type] == NULL)
return -ENOENT;
if (NLMSG_LENGTH(sizeof(struct inet_diag_req)) > skb->len)
goto err_inval;
if (nlh->nlmsg_flags&NLM_F_DUMP) {
if (nlh->nlmsg_len >
(4 + NLMSG_SPACE(sizeof(struct inet_diag_req)))) {
struct rtattr *rta = (void *)(NLMSG_DATA(nlh) +
sizeof(struct inet_diag_req));
if (rta->rta_type != INET_DIAG_REQ_BYTECODE ||
rta->rta_len < 8 ||
rta->rta_len >
(nlh->nlmsg_len -
NLMSG_SPACE(sizeof(struct inet_diag_req))))
goto err_inval;
if (inet_diag_bc_audit(RTA_DATA(rta), RTA_PAYLOAD(rta)))
goto err_inval;
}
return netlink_dump_start(idiagnl, skb, nlh,
inet_diag_dump,
inet_diag_dump_done);
} else {
return inet_diag_get_exact(skb, nlh);
}
err_inval:
return -EINVAL;
}
static inline void inet_diag_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 = inet_diag_rcv_msg(skb, nlh);
if (err || nlh->nlmsg_flags & NLM_F_ACK)
netlink_ack(skb, nlh, err);
}
}
static void inet_diag_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 21:55:09 +00:00
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 21:55:09 +00:00
while (qlen-- && (skb = skb_dequeue(&sk->sk_receive_queue))) {
inet_diag_rcv_skb(skb);
kfree_skb(skb);
}
}
static DEFINE_SPINLOCK(inet_diag_register_lock);
int inet_diag_register(const struct inet_diag_handler *h)
{
const __u16 type = h->idiag_type;
int err = -EINVAL;
if (type >= INET_DIAG_GETSOCK_MAX)
goto out;
spin_lock(&inet_diag_register_lock);
err = -EEXIST;
if (inet_diag_table[type] == NULL) {
inet_diag_table[type] = h;
err = 0;
}
spin_unlock(&inet_diag_register_lock);
out:
return err;
}
EXPORT_SYMBOL_GPL(inet_diag_register);
void inet_diag_unregister(const struct inet_diag_handler *h)
{
const __u16 type = h->idiag_type;
if (type >= INET_DIAG_GETSOCK_MAX)
return;
spin_lock(&inet_diag_register_lock);
inet_diag_table[type] = NULL;
spin_unlock(&inet_diag_register_lock);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(inet_diag_unregister);
static int __init inet_diag_init(void)
{
const int inet_diag_table_size = (INET_DIAG_GETSOCK_MAX *
sizeof(struct inet_diag_handler *));
int err = -ENOMEM;
inet_diag_table = kmalloc(inet_diag_table_size, GFP_KERNEL);
if (!inet_diag_table)
goto out;
memset(inet_diag_table, 0, inet_diag_table_size);
idiagnl = netlink_kernel_create(NETLINK_INET_DIAG, inet_diag_rcv,
THIS_MODULE);
if (idiagnl == NULL)
goto out_free_table;
err = 0;
out:
return err;
out_free_table:
kfree(inet_diag_table);
goto out;
}
static void __exit inet_diag_exit(void)
{
sock_release(idiagnl->sk_socket);
kfree(inet_diag_table);
}
module_init(inet_diag_init);
module_exit(inet_diag_exit);
MODULE_LICENSE("GPL");