-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512
Ok, "allow-state"/"deny-state" was very limited idea.
Here is more universal mechanism: new "keep-state-only" (aliased as
"record-only") option, which works exactly as "keep-state" BUT cancel
match of rule after state creation. It allows to write stateful + nat
firewall as easy as:
nat 1 config if outIface
1000 skipto 2000 in
skipto 3000 out
deny all from any to any // Safeguard
2000 skipto 4000 recv inIface
skipto 6000 recv outIface
deny all from any to any // Safeguard
3000 skipto 5000 xmit inIface
skipto 7000 xmit outIface
deny all from any to any // Safeguard
4000 // For sake of simplicity!
// Real firewall will have some checks about local network here
allow all from any to any
deny all from any to any // Safeguard
5000 // For sake of simplicity!
// Real firewall will have some checks about local network here
allow all from any to any
deny all from any to any // Safeguard
6000 deny all not dst-ip $EXT_IP
nat 1 all from any to any
// All enabled with "keep-state-only" at block 7000 before NAT
check-state all from any to any
// Here could be accept rules for our servers or servers in DMZ
// Disable everything else
deny all from any to any
7000 // Here goes rules which could DISABLE outbound external traffic
// Create state for "check-state" at block 6000 and fallthrough
allow keep-state-only
allow src-ip $EXT_IP // Save NAT some work
nat 1 all from any to any
allow all from any to any
deny all from any to any // Safeguard
And variants with multiple NATs and "nat global" becomes as easy as
this, too! No stupid "skipto", no "keep-state" at "incoming from local
network" parts of firewall, nothing!
P.S. I HATE this "all any to any" part!
- --
// Lev Serebryakov
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Index: sbin/ipfw/ipfw.8
===================================================================
--- sbin/ipfw/ipfw.8 (revision 278151)
+++ sbin/ipfw/ipfw.8 (working copy)
@@ -166,7 +166,8 @@
depending on how the kernel is configured.
.Pp
If the ruleset includes one or more rules with the
-.Cm keep-state
+.Cm keep-state ,
+.Cm keep-state-only
or
.Cm limit
option,
@@ -180,7 +181,8 @@
Dynamic rules, which have a limited lifetime, are checked
at the first occurrence of a
.Cm check-state ,
-.Cm keep-state
+.Cm keep-state ,
+.Cm keep-state-only
or
.Cm limit
rule, and are typically used to open the firewall on-demand to
@@ -582,7 +584,8 @@
packet delivery.
.Pp
Note: this condition is checked before any other condition, including
-ones such as keep-state or check-state which might have side effects.
+ones such as keep-state, keep-stat-only or check-state which might have
+side effects.
.It Cm log Op Cm logamount Ar number
Packets matching a rule with the
.Cm log
@@ -748,7 +751,8 @@
If no
.Cm check-state
rule is found, the dynamic ruleset is checked at the first
-.Cm keep-state
+.Cm keep-state ,
+.Cm keep-state-only ,
or
.Cm limit
rule.
@@ -1583,6 +1587,14 @@
.Xr sysctl 8
variables), and the lifetime is refreshed every time a matching
packet is found.
+.It Cm keep-state-only | record-only
+Upon a match, the firewall will create a dynamic rule as if
+.Cm keep-state
+was specified, but after that match is cancelled and the search
+continues with the next rule.
+On dynamic rule match action, specified in this rule,
+performed as if rule contains
+.Cm keep-state .
.It Cm layer2
Matches only layer2 packets, i.e., those passed to
.Nm
Index: sbin/ipfw/ipfw2.c
===================================================================
--- sbin/ipfw/ipfw2.c (revision 278151)
+++ sbin/ipfw/ipfw2.c (working copy)
@@ -292,6 +292,8 @@
{ "in", TOK_IN },
{ "limit", TOK_LIMIT },
{ "keep-state", TOK_KEEPSTATE },
+ { "record-state", TOK_STATE_ONLY },
+ { "keep-state-only", TOK_STATE_ONLY },
{ "bridged", TOK_LAYER2 },
{ "layer2", TOK_LAYER2 },
{ "out", TOK_OUT },
@@ -1993,6 +1995,10 @@
bprintf(bp, " keep-state");
break;
+ case O_STATE_ONLY:
+ bprintf(bp, " keep-state-only");
+ break;
+
case O_LIMIT: {
struct _s_x *p = limit_masks;
ipfw_insn_limit *c = (ipfw_insn_limit *)cmd;
@@ -4335,14 +4341,16 @@
break;
case TOK_KEEPSTATE:
+ case TOK_STATE_ONLY:
if (open_par)
- errx(EX_USAGE, "keep-state cannot be part "
+ errx(EX_USAGE, "keep-state or keep-state-only
cannot be part "
"of an or block");
if (have_state)
errx(EX_USAGE, "only one of keep-state "
"and limit is allowed");
have_state = cmd;
- fill_cmd(cmd, O_KEEP_STATE, 0, 0);
+ fill_cmd(cmd, i == TOK_KEEPSTATE ?
+ O_KEEP_STATE : O_STATE_ONLY, 0, 0);
break;
case TOK_LIMIT: {
@@ -4585,7 +4593,7 @@
dst = next_cmd(dst, &rblen);
}
- /* copy all commands but O_LOG, O_KEEP_STATE, O_LIMIT, O_ALTQ, O_TAG */
+ /* copy all commands but O_LOG, O_KEEP_STATE, O_STATE_ONLY, O_LIMIT,
O_ALTQ, O_TAG */
for (src = (ipfw_insn *)cmdbuf; src != cmd; src += i) {
i = F_LEN(src);
CHECK_RBUFLEN(i);
@@ -4593,6 +4601,7 @@
switch (src->opcode) {
case O_LOG:
case O_KEEP_STATE:
+ case O_STATE_ONLY:
case O_LIMIT:
case O_ALTQ:
case O_TAG:
Index: sbin/ipfw/ipfw2.h
===================================================================
--- sbin/ipfw/ipfw2.h (revision 278151)
+++ sbin/ipfw/ipfw2.h (working copy)
@@ -227,6 +227,7 @@
TOK_LOCK,
TOK_UNLOCK,
TOK_VLIST,
+ TOK_STATE_ONLY,
};
/*
Index: sys/netinet/ip_fw.h
===================================================================
--- sys/netinet/ip_fw.h (revision 278151)
+++ sys/netinet/ip_fw.h (working copy)
@@ -252,6 +252,8 @@
O_DSCP, /* 2 u32 = DSCP mask */
O_SETDSCP, /* arg1=DSCP value */
O_IP_FLOW_LOOKUP, /* arg1=table number, u32=value */
+
+ O_STATE_ONLY, /* none */
O_LAST_OPCODE /* not an opcode! */
};
Index: sys/netpfil/ipfw/ip_fw2.c
===================================================================
--- sys/netpfil/ipfw/ip_fw2.c (revision 278151)
+++ sys/netpfil/ipfw/ip_fw2.c (working copy)
@@ -2107,9 +2107,9 @@
* O_TAG, O_LOG and O_ALTQ action parameters:
* perform some action and set match = 1;
*
- * O_LIMIT and O_KEEP_STATE: these opcodes are
- * not real 'actions', and are stored right
- * before the 'action' part of the rule.
+ * O_LIMIT, O_KEEP_STATE and O_STATE_ONLY: these
+ * opcodes are not real 'actions', and are stored
+ * right before the 'action' part of the rule.
* These opcodes try to install an entry in the
* state tables; if successful, we continue with
* the next opcode (match=1; break;), otherwise
@@ -2126,9 +2126,20 @@
* further instances of these opcodes become NOPs.
* The jump to the next rule is done by setting
* l=0, cmdlen=0.
+ *
+ * O_STATE_ONLY: this opcode is not real 'action'
+ * too, and is stored right before the 'action'
+ * part of the rule, right after O_KEEP_STATE
+ * opcode. It causes match failure so real
+ * 'action' could be executed only if rule
+ * is checked via dynamic rule from state
+ * table, as in such case execution starts
+ * from true 'action' opcode directly.
+ *
*/
case O_LIMIT:
case O_KEEP_STATE:
+ case O_STATE_ONLY:
if (ipfw_install_state(chain, f,
(ipfw_insn_limit *)cmd, args, tablearg)) {
/* error or limit violation */
@@ -2136,7 +2147,11 @@
l = 0; /* exit inner loop */
done = 1; /* exit outer loop */
}
- match = 1;
+ if (cmd->opcode == O_STATE_ONLY) {
+ l = 0; /* exit inner loop */
+ match = 0;
+ } else
+ match = 1;
break;
case O_PROBE_STATE:
@@ -2188,6 +2203,7 @@
break;
case O_ACCEPT:
+
retval = 0; /* accept */
l = 0; /* exit inner loop */
done = 1; /* exit outer loop */
@@ -2537,7 +2553,7 @@
done = 1; /* exit outer loop */
break;
}
-
+
default:
panic("-- unknown opcode %d\n", cmd->opcode);
} /* end of switch() on opcodes */
Index: sys/netpfil/ipfw/ip_fw_dynamic.c
===================================================================
--- sys/netpfil/ipfw/ip_fw_dynamic.c (revision 278151)
+++ sys/netpfil/ipfw/ip_fw_dynamic.c (working copy)
@@ -708,6 +708,7 @@
switch (cmd->o.opcode) {
case O_KEEP_STATE: /* bidir rule */
+ case O_STATE_ONLY:
q = add_dyn_rule(&args->f_id, i, O_KEEP_STATE, rule);
break;
@@ -1357,6 +1358,7 @@
switch (cmd->opcode) {
case O_LIMIT:
case O_KEEP_STATE:
+ case O_STATE_ONLY:
case O_PROBE_STATE:
case O_CHECK_STATE:
return (1);
Index: sys/netpfil/ipfw/ip_fw_sockopt.c
===================================================================
--- sys/netpfil/ipfw/ip_fw_sockopt.c (revision 278151)
+++ sys/netpfil/ipfw/ip_fw_sockopt.c (working copy)
@@ -1433,6 +1433,7 @@
switch (cmd->opcode) {
case O_PROBE_STATE:
case O_KEEP_STATE:
+ case O_STATE_ONLY:
case O_PROTO:
case O_IP_SRC_ME:
case O_IP_DST_ME:
ipfw-state-only.diff.sig
Description: Binary data
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