mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-30 14:19:16 +00:00
Code Issues Releases Wiki Activity

netfilter: x_tables: enforce unique and ascending entry points

Browse source 
Harmless from kernel point of view, but iptables assumes that this is
true when decoding a ruleset.

iptables walks the dumped blob from kernel, and, for each entry that
creates a new chain it prints out rule/chain information.
Base chains (hook entry points) are thus only shown when they appear
in the rule blob.  One base chain that is referenced multiple times
in hook blob is then only printed once.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2018-02-27 19:42:30 +01:00 committed by Pablo Neira Ayuso
parent 1b293e30f7
commit e816a2ce49
1 changed files with 30 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
net/netfilter/x_tables.c
View file

@ -529,10 +529,15 @@ static int xt_check_entry_match(const char *match, const char *target,
*/
int xt_check_table_hooks(const struct xt_table_info *info, unsigned int valid_hooks)
{
unsigned int i;
const char *err = "unsorted underflow";
unsigned int i, max_uflow, max_entry;
bool check_hooks = false;
BUILD_BUG_ON(ARRAY_SIZE(info->hook_entry) != ARRAY_SIZE(info->underflow));
max_entry = 0;
max_uflow = 0;
for (i = 0; i < ARRAY_SIZE(info->hook_entry); i++) {
if (!(valid_hooks & (1 << i)))
continue;
@ -541,9 +546,33 @@ int xt_check_table_hooks(const struct xt_table_info *info, unsigned int valid_ho
return -EINVAL;
if (info->underflow[i] == 0xFFFFFFFF)
return -EINVAL;
if (check_hooks) {
if (max_uflow > info->underflow[i])
goto error;
if (max_uflow == info->underflow[i]) {
err = "duplicate underflow";
goto error;
}
if (max_entry > info->hook_entry[i]) {
err = "unsorted entry";
goto error;
}
if (max_entry == info->hook_entry[i]) {
err = "duplicate entry";
goto error;
}
}
max_entry = info->hook_entry[i];
max_uflow = info->underflow[i];
check_hooks = true;
}
return 0;
error:
pr_err_ratelimited("%s at hook %d\n", err, i);
return -EINVAL;
}
EXPORT_SYMBOL(xt_check_table_hooks);