netfilter: x_tables: validate e->target_offset early

commit bdf533de6968e9686df777dc178486f600c6e617 upstream.

We should check that e->target_offset is sane before
mark_source_chains gets called since it will fetch the target entry
for loop detection.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index bcb6e61..a7900b4 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -465,14 +465,12 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
        return 1;
 }
 
-static inline int check_entry(const struct arpt_entry *e, const char *name)
+static inline int check_entry(const struct arpt_entry *e)
 {
        const struct xt_entry_target *t;
 
-       if (!arp_checkentry(&e->arp)) {
-               duprintf("arp_tables: arp check failed %p %s.\n", e, name);
+       if (!arp_checkentry(&e->arp))
                return -EINVAL;
-       }
 
        if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
                return -EINVAL;
@@ -513,10 +511,6 @@ find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
        struct xt_target *target;
        int ret;
 
-       ret = check_entry(e, name);
-       if (ret)
-               return ret;
-
        t = arpt_get_target(e);
        target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
                                        t->u.user.revision);
@@ -561,6 +555,7 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
                                             unsigned int valid_hooks)
 {
        unsigned int h;
+       int err;
 
        if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
            (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
@@ -575,6 +570,10 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
                return -EINVAL;
        }
 
+       err = check_entry(e);
+       if (err)
+               return err;
+
        /* Check hooks & underflows */
        for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
                if (!(valid_hooks & (1 << h)))
@@ -1232,7 +1231,7 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
        }
 
        /* For purposes of check_entry casting the compat entry is fine */
-       ret = check_entry((struct arpt_entry *)e, name);
+       ret = check_entry((struct arpt_entry *)e);
        if (ret)
                return ret;
 

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index f98a1cf..cfa2952 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -561,14 +561,12 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
 }
 
 static int
-check_entry(const struct ipt_entry *e, const char *name)
+check_entry(const struct ipt_entry *e)
 {
        const struct xt_entry_target *t;
 
-       if (!ip_checkentry(&e->ip)) {
-               duprintf("ip check failed %p %s.\n", e, name);
+       if (!ip_checkentry(&e->ip))
                return -EINVAL;
-       }
 
        if (e->target_offset + sizeof(struct xt_entry_target) >
            e->next_offset)
@@ -658,10 +656,6 @@ find_check_entry(struct ipt_entry *e, struct net *net, const char *name,
        struct xt_mtchk_param mtpar;
        struct xt_entry_match *ematch;
 
-       ret = check_entry(e, name);
-       if (ret)
-               return ret;
-
        j = 0;
        mtpar.net       = net;
        mtpar.table     = name;
@@ -725,6 +719,7 @@ check_entry_size_and_hooks(struct ipt_entry *e,
                           unsigned int valid_hooks)
 {
        unsigned int h;
+       int err;
 
        if ((unsigned long)e % __alignof__(struct ipt_entry) != 0 ||
            (unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
@@ -739,6 +734,10 @@ check_entry_size_and_hooks(struct ipt_entry *e,
                return -EINVAL;
        }
 
+       err = check_entry(e);
+       if (err)
+               return err;
+
        /* Check hooks & underflows */
        for (h = 0; h < NF_INET_NUMHOOKS; h++) {
                if (!(valid_hooks & (1 << h)))
@@ -1499,7 +1498,7 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
        }
 
        /* For purposes of check_entry casting the compat entry is fine */
-       ret = check_entry((struct ipt_entry *)e, name);
+       ret = check_entry((struct ipt_entry *)e);
        if (ret)
                return ret;
 

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 2e752b2..503e614 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -583,14 +583,12 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
 }
 
 static int
-check_entry(const struct ip6t_entry *e, const char *name)
+check_entry(const struct ip6t_entry *e)
 {
        const struct xt_entry_target *t;
 
-       if (!ip6_checkentry(&e->ipv6)) {
-               duprintf("ip_tables: ip check failed %p %s.\n", e, name);
+       if (!ip6_checkentry(&e->ipv6))
                return -EINVAL;
-       }
 
        if (e->target_offset + sizeof(struct xt_entry_target) >
            e->next_offset)
@@ -681,10 +679,6 @@ find_check_entry(struct ip6t_entry *e, struct net *net, const char *name,
        struct xt_mtchk_param mtpar;
        struct xt_entry_match *ematch;
 
-       ret = check_entry(e, name);
-       if (ret)
-               return ret;
-
        j = 0;
        mtpar.net       = net;
        mtpar.table     = name;
@@ -748,6 +742,7 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
                           unsigned int valid_hooks)
 {
        unsigned int h;
+       int err;
 
        if ((unsigned long)e % __alignof__(struct ip6t_entry) != 0 ||
            (unsigned char *)e + sizeof(struct ip6t_entry) >= limit) {
@@ -762,6 +757,10 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
                return -EINVAL;
        }
 
+       err = check_entry(e);
+       if (err)
+               return err;
+
        /* Check hooks & underflows */
        for (h = 0; h < NF_INET_NUMHOOKS; h++) {
                if (!(valid_hooks & (1 << h)))
@@ -1523,7 +1522,7 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
        }
 
        /* For purposes of check_entry casting the compat entry is fine */
-       ret = check_entry((struct ip6t_entry *)e, name);
+       ret = check_entry((struct ip6t_entry *)e);
        if (ret)
                return ret;