From f4dc77713f8016d2e8a3295e1c9c53a21f296def Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 14 Jul 2016 17:51:26 +0200 Subject: 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 Tested-by: Jeff Wu Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/ip6_tables.c | 45 ++++++++++++++++++++++------------------- 1 file changed, 24 insertions(+), 21 deletions(-) (limited to 'net/ipv6/netfilter/ip6_tables.c') 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; @@ -787,6 +787,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, return ret; } + return ret; + out_free: + kvfree(offsets); return ret; } -- cgit v1.2.3