[PATCH 3.14 25/29] netfilter: x_tables: add compat version of xt_check_entry_offsets

Greg Kroah-Hartman
2016-06-22T22:39:57Z

From: Florian Westphal <fw@strlen.de>

commit fc1221b3a163d1386d1052184202d5dc50d302d1 upstream.

32bit rulesets have different layout and alignment requirements, so once
more integrity checks get added to xt_check_entry_offsets it will reject
well-formed 32bit rulesets.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/netfilter/x_tables.h | 3 +++
net/ipv4/netfilter/arp_tables.c | 3 ++-
net/ipv4/netfilter/ip_tables.c | 3 ++-
net/ipv6/netfilter/ip6_tables.c | 3 ++-
net/netfilter/x_tables.c | 22 ++++++++++++++++++++++
5 files changed, 31 insertions(+), 3 deletions(-)

--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -435,6 +435,9 @@ void xt_compat_target_from_user(struct x
unsigned int *size);
int xt_compat_target_to_user(const struct xt_entry_target *t,
void __user **dstptr, unsigned int *size);
+int xt_compat_check_entry_offsets(const void *base,
+ unsigned int target_offset,
+ unsigned int next_offset);

#endif /* CONFIG_COMPAT */
#endif /* _X_TABLES_H */
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1244,7 +1244,8 @@ check_compat_entry_size_and_hooks(struct
if (!arp_checkentry(&e->arp))
return -EINVAL;

- ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ ret = xt_compat_check_entry_offsets(e, e->target_offset,
+ e->next_offset);
if (ret)
return ret;

--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1509,7 +1509,8 @@ check_compat_entry_size_and_hooks(struct
if (!ip_checkentry(&e->ip))
return -EINVAL;

- ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ ret = xt_compat_check_entry_offsets(e,
+ e->target_offset, e->next_offset);
if (ret)
return ret;

--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1521,7 +1521,8 @@ check_compat_entry_size_and_hooks(struct
if (!ip6_checkentry(&e->ipv6))
return -EINVAL;

- ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset);
+ ret = xt_compat_check_entry_offsets(e,
+ e->target_offset, e->next_offset);
if (ret)
return ret;

--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -558,6 +558,27 @@ int xt_compat_match_to_user(const struct
return 0;
}
EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
+
+int xt_compat_check_entry_offsets(const void *base,
+ unsigned int target_offset,
+ unsigned int next_offset)
+{
+ const struct compat_xt_entry_target *t;
+ const char *e = base;
+
+ if (target_offset + sizeof(*t) > next_offset)
+ return -EINVAL;
+
+ t = (void *)(e + target_offset);
+ if (t->u.target_size < sizeof(*t))
+ return -EINVAL;
+
+ if (target_offset + t->u.target_size > next_offset)
+ return -EINVAL;
+
+ return 0;
+}
+EXPORT_SYMBOL(xt_compat_check_entry_offsets);
#endif /* CONFIG_COMPAT */

/**
@@ -568,6 +589,7 @@ EXPORT_SYMBOL_GPL(xt_compat_match_to_use
* @next_offset: the arp/ip/ip6_t->next_offset
*
* validates that target_offset and next_offset are sane.
+ * Also see xt_compat_check_entry_offsets for CONFIG_COMPAT version.
*
* The arp/ip/ip6t_entry structure @base must have passed following tests:
* - it must point to a valid memory location