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authorKlement Sekera <ksekera@cisco.com>2019-05-16 14:35:46 +0200
committerOle Trøan <otroan@employees.org>2019-05-20 12:13:11 +0000
commit3a343d42d7bd90753ea6ed48fe750a7a209b1ddf (patch)
treeba831c36c69365d67a2d20d7a6d447b831a1b88e /src/vnet/ip/ip4_reassembly.c
parentb388e1a50603a07e20007141221ca4f4a18ab698 (diff)
reassembly: prevent long chain attack
limit max # of fragments to 3 per packet by default add API option to configure the limit at runtime Change-Id: Ie4b9507bf5c6095b9a5925972b37fe0032f4f9e8 Signed-off-by: Klement Sekera <ksekera@cisco.com>
Diffstat (limited to 'src/vnet/ip/ip4_reassembly.c')
-rw-r--r--src/vnet/ip/ip4_reassembly.c45
1 files changed, 38 insertions, 7 deletions
diff --git a/src/vnet/ip/ip4_reassembly.c b/src/vnet/ip/ip4_reassembly.c
index b38ade09efd..f27351038fe 100644
--- a/src/vnet/ip/ip4_reassembly.c
+++ b/src/vnet/ip/ip4_reassembly.c
@@ -30,6 +30,7 @@
#define IP4_REASS_TIMEOUT_DEFAULT_MS 100
#define IP4_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS 10000 // 10 seconds default
#define IP4_REASS_MAX_REASSEMBLIES_DEFAULT 1024
+#define IP4_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT 3
#define IP4_REASS_HT_LOAD_FACTOR (0.75)
#define IP4_REASS_DEBUG_BUFFERS 0
@@ -57,6 +58,7 @@
typedef enum
{
IP4_REASS_RC_OK,
+ IP4_REASS_RC_TOO_MANY_FRAGMENTS,
IP4_REASS_RC_INTERNAL_ERROR,
IP4_REASS_RC_NO_BUF,
} ip4_reass_rc_t;
@@ -133,7 +135,8 @@ typedef struct
u8 next_index;
// minimum fragment length for this reassembly - used to estimate MTU
u16 min_fragment_length;
-
+ // number of fragments in this reassembly
+ u32 fragments_n;
} ip4_reass_t;
typedef struct
@@ -150,6 +153,9 @@ typedef struct
u32 timeout_ms;
f64 timeout;
u32 expire_walk_interval_ms;
+ // maximum number of fragments in one reassembly
+ u32 max_reass_len;
+ // maximum number of reassemblies
u32 max_reass_n;
// IPv4 runtime
@@ -750,6 +756,7 @@ ip4_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
}
*bi0 = ~0;
reass->min_fragment_length = clib_net_to_host_u16 (fip->length);
+ reass->fragments_n = 1;
return IP4_REASS_RC_OK;
}
reass->min_fragment_length = clib_min (clib_net_to_host_u16 (fip->length),
@@ -907,6 +914,7 @@ ip4_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
}
break;
}
+ ++reass->fragments_n;
if (consumed)
{
if (PREDICT_FALSE (fb->flags & VLIB_BUFFER_IS_TRACED))
@@ -925,6 +933,10 @@ ip4_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
if (consumed)
{
*bi0 = ~0;
+ if (reass->fragments_n > rm->max_reass_len)
+ {
+ rc = IP4_REASS_RC_TOO_MANY_FRAGMENTS;
+ }
}
else
{
@@ -1022,10 +1034,26 @@ ip4_reassembly_inline (vlib_main_t * vm,
case IP4_REASS_RC_OK:
/* nothing to do here */
break;
+ case IP4_REASS_RC_TOO_MANY_FRAGMENTS:
+ vlib_node_increment_counter (vm, node->node_index,
+ IP4_ERROR_REASS_FRAGMENT_CHAIN_TOO_LONG,
+ 1);
+ ip4_reass_on_timeout (vm, rm, reass);
+ ip4_reass_free (rm, rt, reass);
+ goto next_packet;
+ break;
case IP4_REASS_RC_NO_BUF:
- /* fallthrough */
+ vlib_node_increment_counter (vm, node->node_index,
+ IP4_ERROR_REASS_NO_BUF,
+ 1);
+ ip4_reass_on_timeout (vm, rm, reass);
+ ip4_reass_free (rm, rt, reass);
+ goto next_packet;
+ break;
case IP4_REASS_RC_INTERNAL_ERROR:
- /* drop everything and start with a clean slate */
+ vlib_node_increment_counter (vm, node->node_index,
+ IP4_ERROR_REASS_INTERNAL_ERROR,
+ 1);
ip4_reass_on_timeout (vm, rm, reass);
ip4_reass_free (rm, rt, reass);
goto next_packet;
@@ -1176,20 +1204,21 @@ ip4_rehash_cb (clib_bihash_kv_16_8_t * kv, void *_ctx)
static void
ip4_reass_set_params (u32 timeout_ms, u32 max_reassemblies,
- u32 expire_walk_interval_ms)
+ u32 max_reassembly_length, u32 expire_walk_interval_ms)
{
ip4_reass_main.timeout_ms = timeout_ms;
ip4_reass_main.timeout = (f64) timeout_ms / (f64) MSEC_PER_SEC;
ip4_reass_main.max_reass_n = max_reassemblies;
+ ip4_reass_main.max_reass_len = max_reassembly_length;
ip4_reass_main.expire_walk_interval_ms = expire_walk_interval_ms;
}
vnet_api_error_t
ip4_reass_set (u32 timeout_ms, u32 max_reassemblies,
- u32 expire_walk_interval_ms)
+ u32 max_reassembly_length, u32 expire_walk_interval_ms)
{
u32 old_nbuckets = ip4_reass_get_nbuckets ();
- ip4_reass_set_params (timeout_ms, max_reassemblies,
+ ip4_reass_set_params (timeout_ms, max_reassemblies, max_reassembly_length,
expire_walk_interval_ms);
vlib_process_signal_event (ip4_reass_main.vlib_main,
ip4_reass_main.ip4_reass_expire_node_idx,
@@ -1223,10 +1252,11 @@ ip4_reass_set (u32 timeout_ms, u32 max_reassemblies,
vnet_api_error_t
ip4_reass_get (u32 * timeout_ms, u32 * max_reassemblies,
- u32 * expire_walk_interval_ms)
+ u32 * max_reassembly_length, u32 * expire_walk_interval_ms)
{
*timeout_ms = ip4_reass_main.timeout_ms;
*max_reassemblies = ip4_reass_main.max_reass_n;
+ *max_reassembly_length = ip4_reass_main.max_reass_len;
*expire_walk_interval_ms = ip4_reass_main.expire_walk_interval_ms;
return 0;
}
@@ -1256,6 +1286,7 @@ ip4_reass_init_function (vlib_main_t * vm)
ip4_reass_set_params (IP4_REASS_TIMEOUT_DEFAULT_MS,
IP4_REASS_MAX_REASSEMBLIES_DEFAULT,
+ IP4_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT,
IP4_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS);
nbuckets = ip4_reass_get_nbuckets ();