@@ -34,21 +34,11 @@ enum nf_ct_ext_id {
NF_CT_EXT_NUM,
};
-#define NF_CT_EXT_HELPER_TYPE struct nf_conn_help
-#define NF_CT_EXT_NAT_TYPE struct nf_conn_nat
-#define NF_CT_EXT_SEQADJ_TYPE struct nf_conn_seqadj
-#define NF_CT_EXT_ACCT_TYPE struct nf_conn_acct
-#define NF_CT_EXT_ECACHE_TYPE struct nf_conntrack_ecache
-#define NF_CT_EXT_TSTAMP_TYPE struct nf_conn_tstamp
-#define NF_CT_EXT_TIMEOUT_TYPE struct nf_conn_timeout
-#define NF_CT_EXT_LABELS_TYPE struct nf_conn_labels
-#define NF_CT_EXT_SYNPROXY_TYPE struct nf_conn_synproxy
-#define NF_CT_EXT_ACT_CT_TYPE struct nf_conn_act_ct_ext
-
/* Extensions: optional stuff which isn't permanently in struct. */
struct nf_ct_ext {
u8 offset[NF_CT_EXT_NUM];
u8 len;
+ unsigned int gen_id;
char data[] __aligned(8);
};
@@ -62,17 +52,28 @@ static inline bool nf_ct_ext_exist(const struct nf_conn *ct, u8 id)
return (ct->ext && __nf_ct_ext_exist(ct->ext, id));
}
-static inline void *__nf_ct_ext_find(const struct nf_conn *ct, u8 id)
+void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id);
+
+static inline void *nf_ct_ext_find(const struct nf_conn *ct, u8 id)
{
- if (!nf_ct_ext_exist(ct, id))
+ struct nf_ct_ext *ext = ct->ext;
+
+ if (!ext || !__nf_ct_ext_exist(ext, id))
return NULL;
+ if (unlikely(ext->gen_id))
+ return __nf_ct_ext_find(ext, id);
+
return (void *)ct->ext + ct->ext->offset[id];
}
-#define nf_ct_ext_find(ext, id) \
- ((id##_TYPE *)__nf_ct_ext_find((ext), (id)))
/* Add this type, returns pointer to data or NULL. */
void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp);
+/* ext genid. if ext->id != ext_genid, extensions cannot be used
+ * anymore unless conntrack has CONFIRMED bit set.
+ */
+extern atomic_t nf_conntrack_ext_genid;
+void nf_ct_ext_bump_genid(void);
+
#endif /* _NF_CONNTRACK_EXTEND_H */
@@ -17,10 +17,18 @@ struct nf_conn_labels {
unsigned long bits[NF_CT_LABELS_MAX_SIZE / sizeof(long)];
};
+/* Can't use nf_ct_ext_find(), flow dissector cannot use symbols
+ * exported by nf_conntrack module.
+ */
static inline struct nf_conn_labels *nf_ct_labels_find(const struct nf_conn *ct)
{
#ifdef CONFIG_NF_CONNTRACK_LABELS
- return nf_ct_ext_find(ct, NF_CT_EXT_LABELS);
+ struct nf_ct_ext *ext = ct->ext;
+
+ if (!ext || !__nf_ct_ext_exist(ext, NF_CT_EXT_LABELS))
+ return NULL;
+
+ return (void *)ct->ext + ct->ext->offset[NF_CT_EXT_LABELS];
#else
return NULL;
#endif
@@ -876,6 +876,33 @@ static void __nf_conntrack_hash_insert(struct nf_conn *ct,
&nf_conntrack_hash[reply_hash]);
}
+static bool nf_ct_ext_valid_pre(const struct nf_ct_ext *ext)
+{
+ /* if ext->gen_id is not equal to nf_conntrack_ext_genid, some extensions
+ * may contain stale pointers to e.g. helper that has been removed.
+ *
+ * The helper can't clear this because the nf_conn object isn't in
+ * any hash and synchronize_rcu() isn't enough because associated skb
+ * might sit in a queue.
+ */
+ return !ext || ext->gen_id == atomic_read(&nf_conntrack_ext_genid);
+}
+
+static bool nf_ct_ext_valid_post(struct nf_ct_ext *ext)
+{
+ if (!ext)
+ return true;
+
+ if (ext->gen_id != atomic_read(&nf_conntrack_ext_genid))
+ return false;
+
+ /* inserted into conntrack table, nf_ct_iterate_cleanup()
+ * will find it. Disable nf_ct_ext_find() id check.
+ */
+ WRITE_ONCE(ext->gen_id, 0);
+ return true;
+}
+
int
nf_conntrack_hash_check_insert(struct nf_conn *ct)
{
@@ -891,6 +918,11 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
zone = nf_ct_zone(ct);
+ if (!nf_ct_ext_valid_pre(ct->ext)) {
+ NF_CT_STAT_INC(net, insert_failed);
+ return -ETIMEDOUT;
+ }
+
local_bh_disable();
do {
sequence = read_seqcount_begin(&nf_conntrack_generation);
@@ -931,6 +963,13 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
nf_conntrack_double_unlock(hash, reply_hash);
NF_CT_STAT_INC(net, insert);
local_bh_enable();
+
+ if (!nf_ct_ext_valid_post(ct->ext)) {
+ nf_ct_kill(ct);
+ NF_CT_STAT_INC(net, drop);
+ return -ETIMEDOUT;
+ }
+
return 0;
chaintoolong:
NF_CT_STAT_INC(net, chaintoolong);
@@ -1198,6 +1237,11 @@ __nf_conntrack_confirm(struct sk_buff *skb)
return NF_DROP;
}
+ if (!nf_ct_ext_valid_pre(ct->ext)) {
+ NF_CT_STAT_INC(net, insert_failed);
+ goto dying;
+ }
+
pr_debug("Confirming conntrack %p\n", ct);
/* We have to check the DYING flag after unlink to prevent
* a race against nf_ct_get_next_corpse() possibly called from
@@ -1254,6 +1298,16 @@ __nf_conntrack_confirm(struct sk_buff *skb)
nf_conntrack_double_unlock(hash, reply_hash);
local_bh_enable();
+ /* ext area is still valid (rcu read lock is held,
+ * but will go out of scope soon, we need to remove
+ * this conntrack again.
+ */
+ if (!nf_ct_ext_valid_post(ct->ext)) {
+ nf_ct_kill(ct);
+ NF_CT_STAT_INC(net, drop);
+ return NF_DROP;
+ }
+
help = nfct_help(ct);
if (help && help->helper)
nf_conntrack_event_cache(IPCT_HELPER, ct);
@@ -2491,6 +2545,7 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
*/
synchronize_net();
+ nf_ct_ext_bump_genid();
nf_ct_iterate_cleanup(iter, data, 0, 0);
}
EXPORT_SYMBOL_GPL(nf_ct_iterate_destroy);
@@ -27,6 +27,8 @@
#define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */
+atomic_t nf_conntrack_ext_genid __read_mostly = ATOMIC_INIT(1);
+
static const u8 nf_ct_ext_type_len[NF_CT_EXT_NUM] = {
[NF_CT_EXT_HELPER] = sizeof(struct nf_conn_help),
#if IS_ENABLED(CONFIG_NF_NAT)
@@ -116,8 +118,10 @@ void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
if (!new)
return NULL;
- if (!ct->ext)
+ if (!ct->ext) {
memset(new->offset, 0, sizeof(new->offset));
+ new->gen_id = atomic_read(&nf_conntrack_ext_genid);
+ }
new->offset[id] = newoff;
new->len = newlen;
@@ -127,3 +131,29 @@ void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
return (void *)new + newoff;
}
EXPORT_SYMBOL(nf_ct_ext_add);
+
+/* Use nf_ct_ext_find wrapper. This is only useful for unconfirmed entries. */
+void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id)
+{
+ unsigned int gen_id = atomic_read(&nf_conntrack_ext_genid);
+ unsigned int this_id = READ_ONCE(ext->gen_id);
+
+ if (!__nf_ct_ext_exist(ext, id))
+ return NULL;
+
+ if (this_id == 0 || ext->gen_id == gen_id)
+ return (void *)ext + ext->offset[id];
+
+ return NULL;
+}
+EXPORT_SYMBOL(__nf_ct_ext_find);
+
+void nf_ct_ext_bump_genid(void)
+{
+ unsigned int value = atomic_inc_return(&nf_conntrack_ext_genid);
+
+ if (value == UINT_MAX)
+ atomic_set(&nf_conntrack_ext_genid, 1);
+
+ msleep(HZ);
+}