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Modify send_pkt() to return the generated packet and have the caller

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do the subsequent ip_output() in IPFW.  In ipfw_tick(), the keep-alive
packets must be generated from the data that resides under the
stateful lock, but they must not be sent at that time, as this would
cause a lock order reversal with the normal ordering (interface's
lock, then locks belonging to the pfil hooks).

In practice, this caused deadlocks when using IPFW and if_bridge(4)
together to do stateful transparent filtering.

MFC after: 1 week
This commit is contained in:
Brian Feldman 2005-06-10 12:28:17 +00:00
parent 4aea1563d6
commit b34d56f1ef
1 changed files with 32 additions and 8 deletions
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40
sys/netinet/ip_fw2.c
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@ -1372,12 +1372,12 @@ install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
}
/*
* Transmit a TCP packet, containing either a RST or a keepalive.
* Generate a TCP packet, containing either a RST or a keepalive.
* When flags & TH_RST, we are sending a RST packet, because of a
* "reset" action matched the packet.
* Otherwise we are sending a keepalive, and flags & TH_
*/
static void
static struct mbuf *
send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags)
{
struct mbuf *m;
@ -1386,7 +1386,7 @@ send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags)
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == 0)
return;
return (NULL);
m->m_pkthdr.rcvif = (struct ifnet *)0;
m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
m->m_data += max_linkhdr;
@ -1449,7 +1449,7 @@ send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags)
ip->ip_ttl = ip_defttl;
ip->ip_len = m->m_pkthdr.len;
m->m_flags |= M_SKIP_FIREWALL;
ip_output(m, NULL, NULL, 0, NULL, NULL);
return (m);
}
/*
@ -1470,10 +1470,14 @@ send_reject(struct ip_fw_args *args, int code, int offset, int ip_len)
} else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) {
struct tcphdr *const tcp =
L3HDR(struct tcphdr, mtod(args->m, struct ip *));
if ( (tcp->th_flags & TH_RST) == 0)
send_pkt(&(args->f_id), ntohl(tcp->th_seq),
if ( (tcp->th_flags & TH_RST) == 0) {
struct mbuf *m;
m = send_pkt(&(args->f_id), ntohl(tcp->th_seq),
ntohl(tcp->th_ack),
tcp->th_flags | TH_RST);
if (m != NULL)
ip_output(m, NULL, NULL, 0, NULL, NULL);
}
m_freem(args->m);
} else
m_freem(args->m);
@ -3831,12 +3835,21 @@ struct ip_fw *ip_fw_default_rule;
static void
ipfw_tick(void * __unused unused)
{
struct mbuf *m0, *m, *mnext, **mtailp;
int i;
ipfw_dyn_rule *q;
if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0)
goto done;
/*
* We make a chain of packets to go out here -- not deferring
* until after we drop the IPFW dynamic rule lock would result
* in a lock order reversal with the normal packet input -> ipfw
* call stack.
*/
m0 = NULL;
mtailp = &m0;
IPFW_DYN_LOCK();
for (i = 0 ; i < curr_dyn_buckets ; i++) {
for (q = ipfw_dyn_v[i] ; q ; q = q->next ) {
@ -3852,11 +3865,22 @@ ipfw_tick(void * __unused unused)
if (TIME_LEQ(q->expire, time_second))
continue; /* too late, rule expired */
send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0);
*mtailp = send_pkt(&(q->id), q->ack_rev - 1,
q->ack_fwd, TH_SYN);
if (*mtailp != NULL)
mtailp = &(*mtailp)->m_nextpkt;
*mtailp = send_pkt(&(q->id), q->ack_fwd - 1,
q->ack_rev, 0);
if (*mtailp != NULL)
mtailp = &(*mtailp)->m_nextpkt;
}
}
IPFW_DYN_UNLOCK();
for (m = mnext = m0; m != NULL; m = mnext) {
mnext = m->m_nextpkt;
m->m_nextpkt = NULL;
ip_output(m, NULL, NULL, 0, NULL, NULL);
}
done:
callout_reset(&ipfw_timeout, dyn_keepalive_period*hz, ipfw_tick, NULL);
}