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@xxxxxxxxx>
Tested-by: Jeff Wu <wujiafu@xxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
v3:
- also use bsearch in arptables
v2:
- get rid of unneeded 'offsets &&' clause in if-test
- add Tested-by Tag from Jeff Wu
- fixup some parts of commit message wrt. size of example ruleset
include/linux/netfilter/x_tables.h | 4 +++
net/ipv4/netfilter/arp_tables.c | 47 ++++++++++++++++++-----------------
net/ipv4/netfilter/ip_tables.c | 45 ++++++++++++++++++----------------
net/ipv6/netfilter/ip6_tables.c | 45 ++++++++++++++++++----------------
net/netfilter/x_tables.c | 50 ++++++++++++++++++++++++++++++++++++++
5 files changed, 127 insertions(+), 64 deletions(-)
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index dc4f58a..5f968a3 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -246,6 +246,10 @@ int xt_check_entry_offsets(const void *base, const char *elems,
unsigned int target_offset,
unsigned int next_offset);
+unsigned int *xt_alloc_entry_offsets(unsigned int size);
+bool xt_find_jump_offset(const unsigned int *offsets,
+ unsigned int target, unsigned int size);
+
int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
bool inv_proto);
int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 2033f92..9a971e3 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -300,23 +300,12 @@ static inline bool unconditional(const struct arpt_entry *e)
memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
}
-static bool find_jump_target(const struct xt_table_info *t,
- const struct arpt_entry *target)
-{
- struct arpt_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;
@@ -389,10 +378,11 @@ static int 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 arpt_entry *)
(entry0 + newpos);
- if (!find_jump_target(newinfo, e))
- return 0;
} else {
/* ... this is a fallthru */
newpos = pos + e->next_offset;
@@ -544,6 +534,7 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0,
const struct arpt_replace *repl)
{
struct arpt_entry *iter;
+ unsigned int *offsets;
unsigned int i;
int ret = 0;
@@ -556,6 +547,9 @@ static int translate_table(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. */
@@ -566,17 +560,20 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0,
repl->underflow,
repl->valid_hooks);
if (ret != 0)
- break;
+ goto out_free;
+ if (i < repl->num_entries)
+ offsets[i] = (void *)iter - entry0;
++i;
if (strcmp(arpt_get_target(iter)->u.user.name,
XT_ERROR_TARGET) == 0)
++newinfo->stacksize;
}
if (ret != 0)
- return ret;
+ goto out_free;
+ ret = -EINVAL;
if (i != repl->num_entries)
- return -EINVAL;
+ goto out_free;
/* Check hooks all assigned */
for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
@@ -584,13 +581,16 @@ static int translate_table(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;
@@ -611,6 +611,9 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0,
}
return ret;
+ out_free:
+ kvfree(offsets);
+ return ret;
}
static void get_counters(const struct xt_table_info *t,
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 54906e0..1c909f3 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -375,23 +375,12 @@ ipt_do_table(struct sk_buff *skb,
else return verdict;
}
-static bool find_jump_target(const struct xt_table_info *t,
- const struct ipt_entry *target)
-{
- struct ipt_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;
@@ -460,10 +449,11 @@ 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 ipt_entry *)
(entry0 + newpos);
- if (!find_jump_target(newinfo, e))
- return 0;
} else {
/* ... this is a fallthru */
newpos = pos + e->next_offset;
@@ -696,6 +686,7 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
const struct ipt_replace *repl)
{
struct ipt_entry *iter;
+ unsigned int *offsets;
unsigned int i;
int ret = 0;
@@ -708,6 +699,9 @@ 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) {
@@ -717,15 +711,18 @@ 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(ipt_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++) {
@@ -733,13 +730,16 @@ 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;
@@ -760,6 +760,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
}
return ret;
+ out_free:
+ kvfree(offsets);
+ return ret;
}
static void
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 63e06c3..48b3d56 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
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 2675d58..95e044a 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -702,6 +702,56 @@ int xt_check_entry_offsets(const void *base,
}
EXPORT_SYMBOL(xt_check_entry_offsets);
+/**
+ * xt_alloc_entry_offsets - allocate array to store rule head offsets
+ *
+ * @size: number of entries
+ *
+ * Return: NULL or kmalloc'd or vmalloc'd array
+ */
+unsigned int *xt_alloc_entry_offsets(unsigned int size)
+{
+ unsigned int *off;
+
+ off = kcalloc(size, sizeof(unsigned int), GFP_KERNEL | __GFP_NOWARN);
+
+ if (off)
+ return off;
+
+ if (size < (SIZE_MAX / sizeof(unsigned int)))
+ off = vmalloc(size * sizeof(unsigned int));
+
+ return off;
+}
+EXPORT_SYMBOL(xt_alloc_entry_offsets);
+
+/**
+ * xt_find_jump_offset - check if target is a valid jump offset
+ *
+ * @offsets: array containing all valid rule start offsets of a rule blob
+ * @target: the jump target to search for
+ * @size: entries in @offset
+ */
+bool xt_find_jump_offset(const unsigned int *offsets,
+ unsigned int target, unsigned int size)
+{
+ int m, low = 0, hi = size;
+
+ while (hi > low) {
+ m = (low + hi) / 2u;
+
+ if (offsets[m] > target)
+ hi = m;
+ else if (offsets[m] < target)
+ low = m + 1;
+ else
+ return true;
+ }
+
+ return false;
+}
+EXPORT_SYMBOL(xt_find_jump_offset);
+
int xt_check_target(struct xt_tgchk_param *par,
unsigned int size, u_int8_t proto, bool inv_proto)
{
--
2.7.3
--
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