aboutsummaryrefslogtreecommitdiffstats
path: root/net/ipv4/netfilter/ip_tables.c
diff options
context:
space:
mode:
authorJan Engelhardt <jengelh@medozas.de>2010-04-19 16:05:10 +0200
committerPatrick McHardy <kaber@trash.net>2010-04-19 16:05:10 +0200
commitf3c5c1bfd430858d3a05436f82c51e53104feb6b (patch)
treeada5b570b66e141e79fdb256f69e2541a3d30c04 /net/ipv4/netfilter/ip_tables.c
parente281b19897dc21c1071802808d461627d747a877 (diff)
downloadmrst-s0i3-test-f3c5c1bfd430858d3a05436f82c51e53104feb6b.tar.gz
mrst-s0i3-test-f3c5c1bfd430858d3a05436f82c51e53104feb6b.tar.xz
mrst-s0i3-test-f3c5c1bfd430858d3a05436f82c51e53104feb6b.zip
netfilter: xtables: make ip_tables reentrant
Currently, the table traverser stores return addresses in the ruleset itself (struct ip6t_entry->comefrom). This has a well-known drawback: the jumpstack is overwritten on reentry, making it necessary for targets to return absolute verdicts. Also, the ruleset (which might be heavy memory-wise) needs to be replicated for each CPU that can possibly invoke ip6t_do_table. This patch decouples the jumpstack from struct ip6t_entry and instead puts it into xt_table_info. Not being restricted by 'comefrom' anymore, we can set up a stack as needed. By default, there is room allocated for two entries into the traverser. arp_tables is not touched though, because there is just one/two modules and further patches seek to collapse the table traverser anyhow. Signed-off-by: Jan Engelhardt <jengelh@medozas.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/ipv4/netfilter/ip_tables.c')
-rw-r--r--net/ipv4/netfilter/ip_tables.c65
1 files changed, 35 insertions, 30 deletions
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 18c5b1573f3..70900ecf88e 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -321,8 +321,6 @@ ipt_do_table(struct sk_buff *skb,
const struct net_device *out,
struct xt_table *table)
{
-#define tb_comefrom ((struct ipt_entry *)table_base)->comefrom
-
static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
const struct iphdr *ip;
bool hotdrop = false;
@@ -330,7 +328,8 @@ ipt_do_table(struct sk_buff *skb,
unsigned int verdict = NF_DROP;
const char *indev, *outdev;
const void *table_base;
- struct ipt_entry *e, *back;
+ struct ipt_entry *e, **jumpstack;
+ unsigned int *stackptr, origptr, cpu;
const struct xt_table_info *private;
struct xt_match_param mtpar;
struct xt_target_param tgpar;
@@ -356,19 +355,23 @@ ipt_do_table(struct sk_buff *skb,
IP_NF_ASSERT(table->valid_hooks & (1 << hook));
xt_info_rdlock_bh();
private = table->private;
- table_base = private->entries[smp_processor_id()];
+ cpu = smp_processor_id();
+ table_base = private->entries[cpu];
+ jumpstack = (struct ipt_entry **)private->jumpstack[cpu];
+ stackptr = &private->stackptr[cpu];
+ origptr = *stackptr;
e = get_entry(table_base, private->hook_entry[hook]);
- /* For return from builtin chain */
- back = get_entry(table_base, private->underflow[hook]);
+ pr_devel("Entering %s(hook %u); sp at %u (UF %p)\n",
+ table->name, hook, origptr,
+ get_entry(table_base, private->underflow[hook]));
do {
const struct ipt_entry_target *t;
const struct xt_entry_match *ematch;
IP_NF_ASSERT(e);
- IP_NF_ASSERT(back);
if (!ip_packet_match(ip, indev, outdev,
&e->ip, mtpar.fragoff)) {
no_match:
@@ -403,17 +406,28 @@ ipt_do_table(struct sk_buff *skb,
verdict = (unsigned)(-v) - 1;
break;
}
- e = back;
- back = get_entry(table_base, back->comefrom);
+ if (*stackptr == 0) {
+ e = get_entry(table_base,
+ private->underflow[hook]);
+ pr_devel("Underflow (this is normal) "
+ "to %p\n", e);
+ } else {
+ e = jumpstack[--*stackptr];
+ pr_devel("Pulled %p out from pos %u\n",
+ e, *stackptr);
+ e = ipt_next_entry(e);
+ }
continue;
}
if (table_base + v != ipt_next_entry(e) &&
!(e->ip.flags & IPT_F_GOTO)) {
- /* Save old back ptr in next entry */
- struct ipt_entry *next = ipt_next_entry(e);
- next->comefrom = (void *)back - table_base;
- /* set back pointer to next entry */
- back = next;
+ if (*stackptr >= private->stacksize) {
+ verdict = NF_DROP;
+ break;
+ }
+ jumpstack[(*stackptr)++] = e;
+ pr_devel("Pushed %p into pos %u\n",
+ e, *stackptr - 1);
}
e = get_entry(table_base, v);
@@ -426,18 +440,7 @@ ipt_do_table(struct sk_buff *skb,
tgpar.targinfo = t->data;
-#ifdef CONFIG_NETFILTER_DEBUG
- tb_comefrom = 0xeeeeeeec;
-#endif
verdict = t->u.kernel.target->target(skb, &tgpar);
-#ifdef CONFIG_NETFILTER_DEBUG
- if (tb_comefrom != 0xeeeeeeec && verdict == IPT_CONTINUE) {
- printk("Target %s reentered!\n",
- t->u.kernel.target->name);
- verdict = NF_DROP;
- }
- tb_comefrom = 0x57acc001;
-#endif
/* Target might have changed stuff. */
ip = ip_hdr(skb);
if (verdict == IPT_CONTINUE)
@@ -447,7 +450,9 @@ ipt_do_table(struct sk_buff *skb,
break;
} while (!hotdrop);
xt_info_rdunlock_bh();
-
+ pr_devel("Exiting %s; resetting sp from %u to %u\n",
+ __func__, *stackptr, origptr);
+ *stackptr = origptr;
#ifdef DEBUG_ALLOW_ALL
return NF_ACCEPT;
#else
@@ -455,8 +460,6 @@ ipt_do_table(struct sk_buff *skb,
return NF_DROP;
else return verdict;
#endif
-
-#undef tb_comefrom
}
/* Figures out from what hook each rule can be called: returns 0 if
@@ -838,6 +841,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
if (ret != 0)
return ret;
++i;
+ if (strcmp(ipt_get_target(iter)->u.user.name,
+ XT_ERROR_TARGET) == 0)
+ ++newinfo->stacksize;
}
if (i != repl->num_entries) {
@@ -2086,8 +2092,7 @@ struct xt_table *ipt_register_table(struct net *net,
{
int ret;
struct xt_table_info *newinfo;
- struct xt_table_info bootstrap
- = { 0, 0, 0, { 0 }, { 0 }, { } };
+ struct xt_table_info bootstrap = {0};
void *loc_cpu_entry;
struct xt_table *new_table;