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authorFlorian Westphal <fw@strlen.de>2016-07-14 17:51:26 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2016-07-18 21:35:23 +0200
commitf4dc77713f8016d2e8a3295e1c9c53a21f296def (patch)
tree62b548c4d29c9a509964a356469c20d41d2e17a7 /net/ipv6
parent3101e0fc1f6e809d38fbb5845c6c5eb0eefeda07 (diff)
netfilter: x_tables: speed up jump target validation
The dummy ruleset I used to test the original validation change was broken, most rules were unreachable and were not tested by mark_source_chains(). In some cases rulesets that used to load in a few seconds now require several minutes. sample ruleset that shows the behaviour: echo "*filter" for i in $(seq 0 100000);do printf ":chain_%06x - [0:0]\n" $i done for i in $(seq 0 100000);do printf -- "-A INPUT -j chain_%06x\n" $i printf -- "-A INPUT -j chain_%06x\n" $i printf -- "-A INPUT -j chain_%06x\n" $i done echo COMMIT [ pipe result into iptables-restore ] This ruleset will be about 74mbyte in size, with ~500k searches though all 500k[1] rule entries. iptables-restore will take forever (gave up after 10 minutes) Instead of always searching the entire blob for a match, fill an array with the start offsets of every single ipt_entry struct, then do a binary search to check if the jump target is present or not. After this change ruleset restore times get again close to what one gets when reverting 36472341017529e (~3 seconds on my workstation). [1] every user-defined rule gets an implicit RETURN, so we get 300k jumps + 100k userchains + 100k returns -> 500k rule entries Fixes: 36472341017529e ("netfilter: x_tables: validate targets of jumps") Reported-by: Jeff Wu <wujiafu@gmail.com> Tested-by: Jeff Wu <wujiafu@gmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/netfilter/ip6_tables.c45
1 files changed, 24 insertions, 21 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 61ed95054efa..552fac2f390a 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -402,23 +402,12 @@ ip6t_do_table(struct sk_buff *skb,
else return verdict;
}
-static bool find_jump_target(const struct xt_table_info *t,
- const struct ip6t_entry *target)
-{
- struct ip6t_entry *iter;
-
- xt_entry_foreach(iter, t->entries, t->size) {
- if (iter == target)
- return true;
- }
- return false;
-}
-
/* Figures out from what hook each rule can be called: returns 0 if
there are loops. Puts hook bitmask in comefrom. */
static int
mark_source_chains(const struct xt_table_info *newinfo,
- unsigned int valid_hooks, void *entry0)
+ unsigned int valid_hooks, void *entry0,
+ unsigned int *offsets)
{
unsigned int hook;
@@ -487,10 +476,11 @@ mark_source_chains(const struct xt_table_info *newinfo,
XT_STANDARD_TARGET) == 0 &&
newpos >= 0) {
/* This a jump; chase it. */
+ if (!xt_find_jump_offset(offsets, newpos,
+ newinfo->number))
+ return 0;
e = (struct ip6t_entry *)
(entry0 + newpos);
- if (!find_jump_target(newinfo, e))
- return 0;
} else {
/* ... this is a fallthru */
newpos = pos + e->next_offset;
@@ -724,6 +714,7 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
const struct ip6t_replace *repl)
{
struct ip6t_entry *iter;
+ unsigned int *offsets;
unsigned int i;
int ret = 0;
@@ -736,6 +727,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
newinfo->underflow[i] = 0xFFFFFFFF;
}
+ offsets = xt_alloc_entry_offsets(newinfo->number);
+ if (!offsets)
+ return -ENOMEM;
i = 0;
/* Walk through entries, checking offsets. */
xt_entry_foreach(iter, entry0, newinfo->size) {
@@ -745,15 +739,18 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
repl->underflow,
repl->valid_hooks);
if (ret != 0)
- return ret;
+ goto out_free;
+ if (i < repl->num_entries)
+ offsets[i] = (void *)iter - entry0;
++i;
if (strcmp(ip6t_get_target(iter)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
+ ret = -EINVAL;
if (i != repl->num_entries)
- return -EINVAL;
+ goto out_free;
/* Check hooks all assigned */
for (i = 0; i < NF_INET_NUMHOOKS; i++) {
@@ -761,13 +758,16 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
if (!(repl->valid_hooks & (1 << i)))
continue;
if (newinfo->hook_entry[i] == 0xFFFFFFFF)
- return -EINVAL;
+ goto out_free;
if (newinfo->underflow[i] == 0xFFFFFFFF)
- return -EINVAL;
+ goto out_free;
}
- if (!mark_source_chains(newinfo, repl->valid_hooks, entry0))
- return -ELOOP;
+ if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
+ ret = -ELOOP;
+ goto out_free;
+ }
+ kvfree(offsets);
/* Finally, each sanity check must pass */
i = 0;
@@ -788,6 +788,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
}
return ret;
+ out_free:
+ kvfree(offsets);
+ return ret;
}
static void