This adds the second check that Rusty wanted to have a long time ago. :)
Signed-off-by: Jan Engelhardt <jengelh@xxxxxxxxxx>
---
net/ipv4/netfilter/arp_tables.c | 21 +++++++++++++++++++--
net/ipv4/netfilter/ip_tables.c | 21 +++++++++++++++++++--
net/ipv6/netfilter/ip6_tables.c | 21 +++++++++++++++++++--
3 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 064082d..7bc11ff 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -533,6 +533,21 @@ out:
return ret;
}
+static bool check_underflow(struct arpt_entry *e)
+{
+ const struct arpt_entry_target *t;
+ unsigned int verdict;
+
+ if (!unconditional(&e->arp))
+ return false;
+ t = arpt_get_target(e);
+ if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
+ return false;
+ verdict = ((struct arpt_standard_target *)t)->verdict;
+ verdict = -verdict - 1;
+ return verdict == NF_DROP || verdict == NF_ACCEPT;
+}
+
static inline int check_entry_size_and_hooks(struct arpt_entry *e,
struct xt_table_info *newinfo,
unsigned char *base,
@@ -564,8 +579,10 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
if ((unsigned char *)e - base == hook_entries[h])
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
- if (!unconditional(&e->arp)) {
- pr_err("Underflows must be unconditional\n");
+ if (!check_underflow(e)) {
+ pr_err("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 6e546d5..0b43fd7 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -708,6 +708,21 @@ find_check_entry(struct ipt_entry *e, const char *name, unsigned int size,
return ret;
}
+static bool check_underflow(struct ipt_entry *e)
+{
+ const struct ipt_entry_target *t;
+ unsigned int verdict;
+
+ if (!unconditional(&e->ip))
+ return false;
+ t = ipt_get_target(e);
+ if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
+ return false;
+ verdict = ((struct ipt_standard_target *)t)->verdict;
+ verdict = -verdict - 1;
+ return verdict == NF_DROP || verdict == NF_ACCEPT;
+}
+
static int
check_entry_size_and_hooks(struct ipt_entry *e,
struct xt_table_info *newinfo,
@@ -740,8 +755,10 @@ check_entry_size_and_hooks(struct ipt_entry *e,
if ((unsigned char *)e - base == hook_entries[h])
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
- if (!unconditional(&e->ip)) {
- pr_err("Underflows must be unconditional\n");
+ if (!check_underflow(e)) {
+ pr_err("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index b0599b9..a5d0c27 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -740,6 +740,21 @@ find_check_entry(struct ip6t_entry *e, const char *name, unsigned int size,
return ret;
}
+static bool check_underflow(struct ip6t_entry *e)
+{
+ const struct ip6t_entry_target *t;
+ unsigned int verdict;
+
+ if (!unconditional(&e->ipv6))
+ return false;
+ t = ip6t_get_target(e);
+ if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
+ return false;
+ verdict = ((struct ip6t_standard_target *)t)->verdict;
+ verdict = -verdict - 1;
+ return verdict == NF_DROP || verdict == NF_ACCEPT;
+}
+
static int
check_entry_size_and_hooks(struct ip6t_entry *e,
struct xt_table_info *newinfo,
@@ -772,8 +787,10 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
if ((unsigned char *)e - base == hook_entries[h])
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
- if (!unconditional(&e->ipv6)) {
- pr_err("Underflows must be unconditional\n");
+ if (!check_underflow(e)) {
+ pr_err("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
--
1.6.3.3
--
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