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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
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')
-rw-r--r--src/vnet/ip/ip.api4
-rw-r--r--src/vnet/ip/ip4_error.h2
-rw-r--r--src/vnet/ip/ip4_reassembly.c45
-rw-r--r--src/vnet/ip/ip4_reassembly.h2
-rw-r--r--src/vnet/ip/ip6_error.h2
-rw-r--r--src/vnet/ip/ip6_reassembly.c40
-rw-r--r--src/vnet/ip/ip6_reassembly.h1
-rw-r--r--src/vnet/ip/ip_api.c3
8 files changed, 86 insertions, 13 deletions
diff --git a/src/vnet/ip/ip.api b/src/vnet/ip/ip.api
index 39d394f709d..afb0960c78a 100644
--- a/src/vnet/ip/ip.api
+++ b/src/vnet/ip/ip.api
@@ -20,7 +20,7 @@
called through a shared memory interface.
*/
-option version = "2.0.0";
+option version = "2.0.1";
import "vnet/ip/ip_types.api";
import "vnet/fib/fib_types.api";
import "vnet/ethernet/ethernet_types.api";
@@ -1085,6 +1085,7 @@ autoreply define ip_reassembly_set
u32 context;
u32 timeout_ms;
u32 max_reassemblies;
+ u32 max_reassembly_length;
u32 expire_walk_interval_ms;
u8 is_ip6;
};
@@ -1102,6 +1103,7 @@ define ip_reassembly_get_reply
i32 retval;
u32 timeout_ms;
u32 max_reassemblies;
+ u32 max_reassembly_length;
u32 expire_walk_interval_ms;
u8 is_ip6;
};
diff --git a/src/vnet/ip/ip4_error.h b/src/vnet/ip/ip4_error.h
index badcc6609e9..d3bf6d79714 100644
--- a/src/vnet/ip/ip4_error.h
+++ b/src/vnet/ip/ip4_error.h
@@ -86,6 +86,8 @@
/* Errors signalled by ip4-reassembly */ \
_ (REASS_DUPLICATE_FRAGMENT, "duplicate/overlapping fragments") \
_ (REASS_LIMIT_REACHED, "drops due to concurrent reassemblies limit") \
+ _ (REASS_FRAGMENT_CHAIN_TOO_LONG, "fragment chain too long (drop)") \
+ _ (REASS_NO_BUF, "out of buffers (drop)") \
_ (REASS_MALFORMED_PACKET, "malformed packets") \
_ (REASS_INTERNAL_ERROR, "drops due to internal reassembly error")
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 ();
diff --git a/src/vnet/ip/ip4_reassembly.h b/src/vnet/ip/ip4_reassembly.h
index 521ca0f1998..4ceb0ab2409 100644
--- a/src/vnet/ip/ip4_reassembly.h
+++ b/src/vnet/ip/ip4_reassembly.h
@@ -30,12 +30,14 @@
* @brief set ip4 reassembly configuration
*/
vnet_api_error_t ip4_reass_set (u32 timeout_ms, u32 max_reassemblies,
+ u32 max_reassembly_length,
u32 expire_walk_interval_ms);
/**
* @brief get ip4 reassembly configuration
*/
vnet_api_error_t ip4_reass_get (u32 * timeout_ms, u32 * max_reassemblies,
+ u32 * max_reassembly_length,
u32 * expire_walk_interval_ms);
vnet_api_error_t ip4_reass_enable_disable (u32 sw_if_index,
diff --git a/src/vnet/ip/ip6_error.h b/src/vnet/ip/ip6_error.h
index 6a20de4f18e..3ca2be61a55 100644
--- a/src/vnet/ip/ip6_error.h
+++ b/src/vnet/ip/ip6_error.h
@@ -81,6 +81,8 @@
_ (REASS_DUPLICATE_FRAGMENT, "duplicate fragments") \
_ (REASS_OVERLAPPING_FRAGMENT, "overlapping fragments") \
_ (REASS_LIMIT_REACHED, "drops due to concurrent reassemblies limit") \
+ _ (REASS_FRAGMENT_CHAIN_TOO_LONG, "fragment chain too long (drop)") \
+ _ (REASS_NO_BUF, "out of buffers (drop)") \
_ (REASS_TIMEOUT, "fragments dropped due to reassembly timeout") \
_ (REASS_INTERNAL_ERROR, "drops due to internal reassembly error")
diff --git a/src/vnet/ip/ip6_reassembly.c b/src/vnet/ip/ip6_reassembly.c
index 9906250cb0f..45cd2b2eaeb 100644
--- a/src/vnet/ip/ip6_reassembly.c
+++ b/src/vnet/ip/ip6_reassembly.c
@@ -30,12 +30,14 @@
#define IP6_REASS_TIMEOUT_DEFAULT_MS 100
#define IP6_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS 10000 // 10 seconds default
#define IP6_REASS_MAX_REASSEMBLIES_DEFAULT 1024
+#define IP6_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT 3
#define IP6_REASS_HT_LOAD_FACTOR (0.75)
typedef enum
{
IP6_REASS_RC_OK,
IP6_REASS_RC_INTERNAL_ERROR,
+ IP6_REASS_RC_TOO_MANY_FRAGMENTS,
IP6_REASS_RC_NO_BUF,
} ip6_reass_rc_t;
@@ -112,6 +114,8 @@ typedef struct
u8 next_index;
// minimum fragment length for this reassembly - used to estimate MTU
u16 min_fragment_length;
+ // number of fragments for this reassembly
+ u32 fragments_n;
} ip6_reass_t;
typedef struct
@@ -128,6 +132,9 @@ 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;
// IPv6 runtime
@@ -744,6 +751,7 @@ ip6_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
*bi0);
reass->min_fragment_length = clib_net_to_host_u16 (fip->payload_length);
consumed = 1;
+ reass->fragments_n = 1;
goto check_if_done_maybe;
}
reass->min_fragment_length =
@@ -797,6 +805,7 @@ ip6_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
}
break;
}
+ ++reass->fragments_n;
check_if_done_maybe:
if (consumed)
{
@@ -816,6 +825,10 @@ check_if_done_maybe:
if (consumed)
{
*bi0 = ~0;
+ if (reass->fragments_n > rm->max_reass_len)
+ {
+ return IP6_REASS_RC_TOO_MANY_FRAGMENTS;
+ }
}
else
{
@@ -989,10 +1002,25 @@ ip6_reassembly_inline (vlib_main_t * vm,
case IP6_REASS_RC_OK:
/* nothing to do here */
break;
+ case IP6_REASS_RC_TOO_MANY_FRAGMENTS:
+ vlib_node_increment_counter (vm, node->node_index,
+ IP6_ERROR_REASS_FRAGMENT_CHAIN_TOO_LONG,
+ 1);
+ ip6_reass_drop_all (vm, rm, reass);
+ ip6_reass_free (rm, rt, reass);
+ goto next_packet;
+ break;
case IP6_REASS_RC_NO_BUF:
- /* fallthrough */
+ vlib_node_increment_counter (vm, node->node_index,
+ IP6_ERROR_REASS_NO_BUF, 1);
+ ip6_reass_drop_all (vm, rm, reass);
+ ip6_reass_free (rm, rt, reass);
+ goto next_packet;
+ break;
case IP6_REASS_RC_INTERNAL_ERROR:
- /* drop everything and start with a clean slate */
+ vlib_node_increment_counter (vm, node->node_index,
+ IP6_ERROR_REASS_INTERNAL_ERROR,
+ 1);
ip6_reass_drop_all (vm, rm, reass);
ip6_reass_free (rm, rt, reass);
goto next_packet;
@@ -1151,20 +1179,21 @@ ip6_rehash_cb (clib_bihash_kv_48_8_t * kv, void *_ctx)
static void
ip6_reass_set_params (u32 timeout_ms, u32 max_reassemblies,
- u32 expire_walk_interval_ms)
+ u32 max_reassembly_length, u32 expire_walk_interval_ms)
{
ip6_reass_main.timeout_ms = timeout_ms;
ip6_reass_main.timeout = (f64) timeout_ms / (f64) MSEC_PER_SEC;
ip6_reass_main.max_reass_n = max_reassemblies;
+ ip6_reass_main.max_reass_len = max_reassembly_length;
ip6_reass_main.expire_walk_interval_ms = expire_walk_interval_ms;
}
vnet_api_error_t
ip6_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 = ip6_reass_get_nbuckets ();
- ip6_reass_set_params (timeout_ms, max_reassemblies,
+ ip6_reass_set_params (timeout_ms, max_reassemblies, max_reassembly_length,
expire_walk_interval_ms);
vlib_process_signal_event (ip6_reass_main.vlib_main,
ip6_reass_main.ip6_reass_expire_node_idx,
@@ -1231,6 +1260,7 @@ ip6_reass_init_function (vlib_main_t * vm)
ip6_reass_set_params (IP6_REASS_TIMEOUT_DEFAULT_MS,
IP6_REASS_MAX_REASSEMBLIES_DEFAULT,
+ IP6_REASS_MAX_REASSEMBLY_LENGTH_DEFAULT,
IP6_REASS_EXPIRE_WALK_INTERVAL_DEFAULT_MS);
nbuckets = ip6_reass_get_nbuckets ();
diff --git a/src/vnet/ip/ip6_reassembly.h b/src/vnet/ip/ip6_reassembly.h
index 5084edaaf8c..1ca2b20813c 100644
--- a/src/vnet/ip/ip6_reassembly.h
+++ b/src/vnet/ip/ip6_reassembly.h
@@ -30,6 +30,7 @@
* @brief set ip6 reassembly configuration
*/
vnet_api_error_t ip6_reass_set (u32 timeout_ms, u32 max_reassemblies,
+ u32 max_reassembly_length,
u32 expire_walk_interval_ms);
/**
diff --git a/src/vnet/ip/ip_api.c b/src/vnet/ip/ip_api.c
index ce3456d77d9..5a6053d1f42 100644
--- a/src/vnet/ip/ip_api.c
+++ b/src/vnet/ip/ip_api.c
@@ -3328,12 +3328,14 @@ vl_api_ip_reassembly_set_t_handler (vl_api_ip_reassembly_set_t * mp)
{
rv = ip6_reass_set (clib_net_to_host_u32 (mp->timeout_ms),
clib_net_to_host_u32 (mp->max_reassemblies),
+ clib_net_to_host_u32 (mp->max_reassembly_length),
clib_net_to_host_u32 (mp->expire_walk_interval_ms));
}
else
{
rv = ip4_reass_set (clib_net_to_host_u32 (mp->timeout_ms),
clib_net_to_host_u32 (mp->max_reassemblies),
+ clib_net_to_host_u32 (mp->max_reassembly_length),
clib_net_to_host_u32 (mp->expire_walk_interval_ms));
}
@@ -3364,6 +3366,7 @@ vl_api_ip_reassembly_get_t_handler (vl_api_ip_reassembly_get_t * mp)
{
rmp->is_ip6 = 0;
ip4_reass_get (&rmp->timeout_ms, &rmp->max_reassemblies,
+ &rmp->max_reassembly_length,
&rmp->expire_walk_interval_ms);
}
rmp->timeout_ms = clib_host_to_net_u32 (rmp->timeout_ms);