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 36472341 (~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: 36472341 ("netfilter: x_tables: validate targets of jumps") Reported-by: NJeff Wu <wujiafu@gmail.com> Tested-by: NJeff Wu <wujiafu@gmail.com> Signed-off-by: NFlorian Westphal <fw@strlen.de> Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Showing
想要评论请 注册 或 登录