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netfilter: xtables: compute exact size needed for jumpstack 

The {arp,ip,ip6tables} jump stack is currently sized based
on the number of user chains.

However, its rather unlikely that every user defined chain jumps to the
next, so lets use the existing loop detection logic to also track the
chain depths.

The stacksize is then set to the largest chain depth seen.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2015-07-14 17:51:06 +02:00 committed by Pablo Neira Ayuso
parent fd2ecda034
commit 98d1bd802c
4 changed files with 49 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
net/ipv4/netfilter/arp_tables.c
View File

@ -372,10 +372,13 @@ static inline bool unconditional(const struct arpt_arp *arp)
/* Figures out from what hook each rule can be called: returns 0 if
* there are loops. Puts hook bitmask in comefrom.
*
* Keeps track of largest call depth seen and stores it in newinfo->stacksize.
*/
static int mark_source_chains(const struct xt_table_info *newinfo,
static int mark_source_chains(struct xt_table_info *newinfo,
unsigned int valid_hooks, void *entry0)
{
unsigned int calldepth, max_calldepth = 0;
unsigned int hook;
/* No recursion; use packet counter to save back ptrs (reset
@ -391,6 +394,7 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
/* Set initial back pointer. */
e->counters.pcnt = pos;
calldepth = 0;
for (;;) {
const struct xt_standard_target *t
@ -445,6 +449,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
(entry0 + pos + size);
e->counters.pcnt = pos;
pos += size;
if (calldepth > 0)
--calldepth;
} else {
int newpos = t->verdict;
@ -459,6 +465,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
return 0;
}
if (entry0 + newpos != arpt_next_entry(e) &&
++calldepth > max_calldepth)
max_calldepth = calldepth;
/* This a jump; chase it. */
duprintf("Jump rule %u -> %u\n",
pos, newpos);
@ -475,6 +485,7 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
next:
duprintf("Finished chain %u\n", hook);
}
newinfo->stacksize = max_calldepth;
return 1;
}
@ -664,9 +675,6 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0,
if (ret != 0)
break;
++i;
if (strcmp(arpt_get_target(iter)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
if (ret != 0)
@ -1439,9 +1447,6 @@ static int translate_compat_table(const char *name,
break;
}
++i;
if (strcmp(arpt_get_target(iter1)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
if (ret) {
/*

28
net/ipv4/netfilter/ip_tables.c
View File

@ -439,11 +439,15 @@ ipt_do_table(struct sk_buff *skb,
}
/* Figures out from what hook each rule can be called: returns 0 if
there are loops. Puts hook bitmask in comefrom. */
* there are loops. Puts hook bitmask in comefrom.
*
* Keeps track of largest call depth seen and stores it in newinfo->stacksize.
*/
static int
mark_source_chains(const struct xt_table_info *newinfo,
mark_source_chains(struct xt_table_info *newinfo,
unsigned int valid_hooks, void *entry0)
{
unsigned int calldepth, max_calldepth = 0;
unsigned int hook;
/* No recursion; use packet counter to save back ptrs (reset
@ -457,6 +461,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
/* Set initial back pointer. */
e->counters.pcnt = pos;
calldepth = 0;
for (;;) {
const struct xt_standard_target *t
@ -518,6 +523,9 @@ mark_source_chains(const struct xt_table_info *newinfo,
(entry0 + pos + size);
e->counters.pcnt = pos;
pos += size;
WARN_ON_ONCE(calldepth == 0);
if (calldepth > 0)
--calldepth;
} else {
int newpos = t->verdict;
@ -531,9 +539,14 @@ mark_source_chains(const struct xt_table_info *newinfo,
newpos);
return 0;
}
if (entry0 + newpos != ipt_next_entry(e) &&
!(e->ip.flags & IPT_F_GOTO) &&
++calldepth > max_calldepth)
max_calldepth = calldepth;
/* This a jump; chase it. */
duprintf("Jump rule %u -> %u\n",
pos, newpos);
duprintf("Jump rule %u -> %u, calldepth %d\n",
pos, newpos, calldepth);
} else {
/* ... this is a fallthru */
newpos = pos + e->next_offset;
@ -547,6 +560,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
next:
duprintf("Finished chain %u\n", hook);
}
newinfo->stacksize = max_calldepth;
return 1;
}
@ -826,9 +840,6 @@ 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) {
@ -1744,9 +1755,6 @@ translate_compat_table(struct net *net,
if (ret != 0)
break;
++i;
if (strcmp(ipt_get_target(iter1)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
if (ret) {
/*

23
net/ipv6/netfilter/ip6_tables.c
View File

@ -452,11 +452,15 @@ ip6t_do_table(struct sk_buff *skb,
}
/* Figures out from what hook each rule can be called: returns 0 if
there are loops. Puts hook bitmask in comefrom. */
* there are loops. Puts hook bitmask in comefrom.
*
* Keeps track of largest call depth seen and stores it in newinfo->stacksize.
*/
static int
mark_source_chains(const struct xt_table_info *newinfo,
mark_source_chains(struct xt_table_info *newinfo,
unsigned int valid_hooks, void *entry0)
{
unsigned int calldepth, max_calldepth = 0;
unsigned int hook;
/* No recursion; use packet counter to save back ptrs (reset
@ -470,6 +474,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
/* Set initial back pointer. */
e->counters.pcnt = pos;
calldepth = 0;
for (;;) {
const struct xt_standard_target *t
@ -531,6 +536,8 @@ mark_source_chains(const struct xt_table_info *newinfo,
(entry0 + pos + size);
e->counters.pcnt = pos;
pos += size;
if (calldepth > 0)
--calldepth;
} else {
int newpos = t->verdict;
@ -544,6 +551,11 @@ mark_source_chains(const struct xt_table_info *newinfo,
newpos);
return 0;
}
if (entry0 + newpos != ip6t_next_entry(e) &&
!(e->ipv6.flags & IP6T_F_GOTO) &&
++calldepth > max_calldepth)
max_calldepth = calldepth;
/* This a jump; chase it. */
duprintf("Jump rule %u -> %u\n",
pos, newpos);
@ -560,6 +572,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
next:
duprintf("Finished chain %u\n", hook);
}
newinfo->stacksize = max_calldepth;
return 1;
}
@ -839,9 +852,6 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
if (ret != 0)
return ret;
++i;
if (strcmp(ip6t_get_target(iter)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
if (i != repl->num_entries) {
@ -1754,9 +1764,6 @@ translate_compat_table(struct net *net,
if (ret != 0)
break;
++i;
if (strcmp(ip6t_get_target(iter1)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
if (ret) {
/*

4
net/netfilter/x_tables.c
View File

@ -749,6 +749,10 @@ static int xt_jumpstack_alloc(struct xt_table_info *i)
if (i->jumpstack == NULL)
return -ENOMEM;
/* ruleset without jumps -- no stack needed */
if (i->stacksize == 0)
return 0;
i->stacksize *= xt_jumpstack_multiplier;
size = sizeof(void *) * i->stacksize;
for_each_possible_cpu(cpu) {