netfilter: x_tables: add compat version of xt_check_entry_offsets

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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index a2d15087372118f496d21e030b1385e06f3cb610..81843aa42a15f0b72a2fedbe288a74fc9114f2de 100644 (file)
--- 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 xt_entry_target *t, void **dstptr,
                                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 */

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 0c7022671ef47c5795e8a527a57c5cf27fcee4c0..bfd6c19477d321755cea427bbb4d1e8afed1ccd3 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1228,7 +1228,8 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
        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;
 

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 5835d11d15450b0c66fd4efc777bfa139af697bd..85805f7fb29b8da9e8f0071db58502e63f3aaef6 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1493,7 +1493,8 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
        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;
 

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 5ce8abd74810ac1337bd41c17fe539c1f50e1d8c..c651fb5dd9533d180d70297829b72698ec121f0b 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1505,7 +1505,8 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
        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;
 

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 1e2ff82d5bf71528276c0acbe121e6d667026b8a..90d5aa512293b865e1b5123aff6f784095fe84ac 100644 (file)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -558,6 +558,27 @@ int xt_compat_match_to_user(const struct xt_entry_match *m,
        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_user);
  * @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