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/*
* Copyright (c) 2016-2019 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vppinfra/error.h>
#include <vnet/feature/feature.h>
#include <vnet/ip/ip.h>
#include <vppinfra/xxhash.h>
typedef struct
{
f64 next_reset;
f64 reset_interval;
u8 *syn_counts;
} syn_filter4_runtime_t;
typedef struct
{
u32 next_index;
int not_a_syn;
u8 filter_value;
} syn_filter4_trace_t;
/* packet trace format function */
static u8 *
format_syn_filter4_trace (u8 * s, va_list * args)
{
CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
syn_filter4_trace_t *t = va_arg (*args, syn_filter4_trace_t *);
s = format (s, "SYN_FILTER4: next index %d, %s",
t->next_index, t->not_a_syn ? "not a syn" : "syn");
if (t->not_a_syn == 0)
s = format (s, ", filter value %d\n", t->filter_value);
else
s = format (s, "\n");
return s;
}
extern vlib_node_registration_t syn_filter4_node;
#define foreach_syn_filter_error \
_(THROTTLED, "TCP SYN packet throttle drops") \
_(OK, "TCP SYN packets passed")
typedef enum
{
#define _(sym,str) SYN_FILTER_ERROR_##sym,
foreach_syn_filter_error
#undef _
SYN_FILTER_N_ERROR,
} syn_filter_error_t;
static char *syn_filter4_error_strings[] = {
#define _(sym,string) string,
foreach_syn_filter_error
#undef _
};
typedef enum
{
SYN_FILTER_NEXT_DROP,
SYN_FILTER_N_NEXT,
} syn_filter_next_t;
extern vnet_feature_arc_registration_t vnet_feat_arc_ip4_local;
VLIB_NODE_FN (syn_filter4_node) (vlib_main_t * vm,
vlib_node_runtime_t * node,
vlib_frame_t * frame)
{
u32 n_left_from, *from, *to_next;
syn_filter_next_t next_index;
u32 ok_syn_packets = 0;
vnet_feature_main_t *fm = &feature_main;
u8 arc_index = vnet_feat_arc_ip4_local.feature_arc_index;
vnet_feature_config_main_t *cm = &fm->feature_config_mains[arc_index];
syn_filter4_runtime_t *rt = (syn_filter4_runtime_t *) node->runtime_data;
f64 now = vlib_time_now (vm);
/* Shut up spurious gcc warnings. */
u8 *c0 = 0, *c1 = 0, *c2 = 0, *c3 = 0;
from = vlib_frame_vector_args (frame);
n_left_from = frame->n_vectors;
next_index = node->cached_next_index;
if (now > rt->next_reset)
{
clib_memset (rt->syn_counts, 0, vec_len (rt->syn_counts));
rt->next_reset = now + rt->reset_interval;
}
while (n_left_from > 0)
{
u32 n_left_to_next;
vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
while (n_left_from >= 8 && n_left_to_next >= 4)
{
u32 bi0, bi1, bi2, bi3;
vlib_buffer_t *b0, *b1, *b2, *b3;
u32 next0, next1, next2, next3;
ip4_header_t *ip0, *ip1, *ip2, *ip3;
tcp_header_t *tcp0, *tcp1, *tcp2, *tcp3;
u32 not_a_syn0 = 1, not_a_syn1 = 1, not_a_syn2 = 1, not_a_syn3 = 1;
u64 hash0, hash1, hash2, hash3;
/* Prefetch next iteration. */
{
vlib_buffer_t *p4, *p5, *p6, *p7;
p4 = vlib_get_buffer (vm, from[4]);
p5 = vlib_get_buffer (vm, from[5]);
p6 = vlib_get_buffer (vm, from[6]);
p7 = vlib_get_buffer (vm, from[7]);
vlib_prefetch_buffer_header (p4, LOAD);
vlib_prefetch_buffer_header (p5, LOAD);
vlib_prefetch_buffer_header (p6, LOAD);
vlib_prefetch_buffer_header (p7, LOAD);
CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);
CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, STORE);
CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, STORE);
}
/* speculatively enqueue b0 and b1 to the current next frame */
to_next[0] = bi0 = from[0];
to_next[1] = bi1 = from[1];
to_next[2] = bi2 = from[2];
to_next[3] = bi3 = from[3];
from += 4;
to_next += 4;
n_left_from -= 4;
n_left_to_next -= 4;
b0 = vlib_get_buffer (vm, bi0);
b1 = vlib_get_buffer (vm, bi1);
b2 = vlib_get_buffer (vm, bi2);
b3 = vlib_get_buffer (vm, bi3);
vnet_get_config_data
(&cm->config_main, &b0->current_config_index,
&next0, 0 /* sizeof (c0[0]) */ );
vnet_get_config_data
(&cm->config_main, &b1->current_config_index,
&next1, 0 /* sizeof (c0[0]) */ );
vnet_get_config_data
(&cm->config_main, &b2->current_config_index,
&next2, 0 /* sizeof (c0[0]) */ );
vnet_get_config_data
(&cm->config_main, &b3->current_config_index,
&next3, 0 /* sizeof (c0[0]) */ );
/* Not TCP? */
ip0 = vlib_buffer_get_current (b0);
if (ip0->protocol != IP_PROTOCOL_TCP)
goto trace00;
tcp0 = ip4_next_header (ip0);
/*
* Not a SYN?
* $$$$ hack: the TCP bitfield flags seem not to compile
* correct code.
*/
if (PREDICT_TRUE (!(tcp0->flags & 0x2)))
goto trace00;
not_a_syn0 = 0;
hash0 = clib_xxhash ((u64) ip0->src_address.as_u32);
c0 = &rt->syn_counts[hash0 & (_vec_len (rt->syn_counts) - 1)];
if (PREDICT_FALSE (*c0 >= 0x80))
{
next0 = SYN_FILTER_NEXT_DROP;
b0->error = node->errors[SYN_FILTER_ERROR_THROTTLED];
goto trace00;
}
*c0 += 1;
ok_syn_packets++;
trace00:
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
&& (b0->flags & VLIB_BUFFER_IS_TRACED)))
{
syn_filter4_trace_t *t =
vlib_add_trace (vm, node, b0, sizeof (*t));
t->not_a_syn = not_a_syn0;
t->next_index = next0;
t->filter_value = not_a_syn0 ? 0 : *c0;
}
/* Not TCP? */
ip1 = vlib_buffer_get_current (b1);
if (ip1->protocol != IP_PROTOCOL_TCP)
goto trace01;
tcp1 = ip4_next_header (ip1);
/*
* Not a SYN?
* $$$$ hack: the TCP bitfield flags seem not to compile
* correct code.
*/
if (PREDICT_TRUE (!(tcp1->flags & 0x2)))
goto trace01;
not_a_syn1 = 0;
hash1 = clib_xxhash ((u64) ip1->src_address.as_u32);
c1 = &rt->syn_counts[hash1 & (_vec_len (rt->syn_counts) - 1)];
if (PREDICT_FALSE (*c1 >= 0x80))
{
next1 = SYN_FILTER_NEXT_DROP;
b1->error = node->errors[SYN_FILTER_ERROR_THROTTLED];
goto trace01;
}
*c1 += 1;
ok_syn_packets++;
trace01:
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
&& (b1->flags & VLIB_BUFFER_IS_TRACED)))
{
syn_filter4_trace_t *t =
vlib_add_trace (vm, node, b1, sizeof (*t));
t->not_a_syn = not_a_syn1;
t->next_index = next1;
t->filter_value = not_a_syn1 ? 0 : *c1;
}
/* Not TCP? */
ip2 = vlib_buffer_get_current (b2);
if (ip2->protocol != IP_PROTOCOL_TCP)
goto trace02;
tcp2 = ip4_next_header (ip2);
/*
* Not a SYN?
* $$$$ hack: the TCP bitfield flags seem not to compile
* correct code.
*/
if (PREDICT_TRUE (!(tcp2->flags & 0x2)))
goto trace02;
not_a_syn2 = 0;
hash2 = clib_xxhash ((u64) ip2->src_address.as_u32);
c2 = &rt->syn_counts[hash2 & (_vec_len (rt->syn_counts) - 1)];
if (PREDICT_FALSE (*c2 >= 0x80))
{
next2 = SYN_FILTER_NEXT_DROP;
b2->error = node->errors[SYN_FILTER_ERROR_THROTTLED];
goto trace02;
}
*c2 += 1;
ok_syn_packets++;
trace02:
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
&& (b2->flags & VLIB_BUFFER_IS_TRACED)))
{
syn_filter4_trace_t *t =
vlib_add_trace (vm, node, b2, sizeof (*t));
t->not_a_syn = not_a_syn2;
t->next_index = next2;
t->filter_value = not_a_syn2 ? 0 : *c2;
}
/* Not TCP? */
ip3 = vlib_buffer_get_current (b3);
if (ip3->protocol != IP_PROTOCOL_TCP)
goto trace03;
tcp3 = ip4_next_header (ip3);
/*
* Not a SYN?
* $$$$ hack: the TCP bitfield flags seem not to compile
* correct code.
*/
if (PREDICT_TRUE (!(tcp3->flags & 0x2)))
goto trace03;
not_a_syn3 = 0;
hash3 = clib_xxhash ((u64) ip3->src_address.as_u32);
c3 = &rt->syn_counts[hash3 & (_vec_len (rt->syn_counts) - 1)];
if (PREDICT_FALSE (*c3 >= 0x80))
{
next3 = SYN_FILTER_NEXT_DROP;
b3->error = node->errors[SYN_FILTER_ERROR_THROTTLED];
goto trace03;
}
*c3 += 1;
ok_syn_packets++;
trace03:
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
&& (b3->flags & VLIB_BUFFER_IS_TRACED)))
{
syn_filter4_trace_t *t =
vlib_add_trace (vm, node, b3, sizeof (*t));
t->not_a_syn = not_a_syn3;
t->next_index = next3;
t->filter_value = not_a_syn3 ? 0 : *c3;
}
vlib_validate_buffer_enqueue_x4 (vm, node, next_index,
to_next, n_left_to_next,
bi0, bi1, bi2, bi3,
next0, next1, next2, next3);
}
while (n_left_from > 0 && n_left_to_next > 0)
{
u32 bi0;
vlib_buffer_t *b0;
u32 next0;
ip4_header_t *ip0;
tcp_header_t *tcp0;
u32 not_a_syn0 = 1;
u32 hash0;
u8 *c0;
/* speculatively enqueue b0 to the current next frame */
bi0 = from[0];
to_next[0] = bi0;
from += 1;
to_next += 1;
n_left_from -= 1;
n_left_to_next -= 1;
b0 = vlib_get_buffer (vm, bi0);
vnet_get_config_data
(&cm->config_main, &b0->current_config_index,
&next0, 0 /* sizeof (c0[0]) */ );
/* Not TCP? */
ip0 = vlib_buffer_get_current (b0);
if (ip0->protocol != IP_PROTOCOL_TCP)
goto trace0;
tcp0 = ip4_next_header (ip0);
/*
* Not a SYN?
* $$$$ hack: the TCP bitfield flags seem not to compile
* correct code.
*/
if (PREDICT_TRUE (!(tcp0->flags & 0x2)))
goto trace0;
not_a_syn0 = 0;
hash0 = clib_xxhash ((u64) ip0->src_address.as_u32);
c0 = &rt->syn_counts[hash0 & (_vec_len (rt->syn_counts) - 1)];
if (PREDICT_FALSE (*c0 >= 0x80))
{
next0 = SYN_FILTER_NEXT_DROP;
b0->error = node->errors[SYN_FILTER_ERROR_THROTTLED];
goto trace0;
}
*c0 += 1;
ok_syn_packets++;
trace0:
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
&& (b0->flags & VLIB_BUFFER_IS_TRACED)))
{
syn_filter4_trace_t *t =
vlib_add_trace (vm, node, b0, sizeof (*t));
t->not_a_syn = not_a_syn0;
t->next_index = next0;
t->filter_value = not_a_syn0 ? 0 : *c0;
}
/* verify speculative enqueue, maybe switch current next frame */
vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
to_next, n_left_to_next,
bi0, next0);
}
vlib_put_next_frame (vm, node, next_index, n_left_to_next);
}
vlib_node_increment_counter (vm, syn_filter4_node.index,
SYN_FILTER_ERROR_OK, ok_syn_packets);
return frame->n_vectors;
}
/* *INDENT-OFF* */
VLIB_REGISTER_NODE (syn_filter4_node) =
{
.name = "syn-filter-4",
.vector_size = sizeof (u32),
.format_trace = format_syn_filter4_trace,
.type = VLIB_NODE_TYPE_INTERNAL,
.runtime_data_bytes = sizeof (syn_filter4_runtime_t),
.n_errors = ARRAY_LEN(syn_filter4_error_strings),
.error_strings = syn_filter4_error_strings,
.n_next_nodes = SYN_FILTER_N_NEXT,
/* edit / add dispositions here */
.next_nodes = {
[SYN_FILTER_NEXT_DROP] = "error-drop",
},
};
/* *INDENT-ON* */
/* *INDENT-OFF* */
VNET_FEATURE_INIT (syn_filter_4, static) =
{
.arc_name = "ip4-local",
.node_name = "syn-filter-4",
.runs_before = VNET_FEATURES("ip4-local-end-of-arc"),
};
/* *INDENT-ON* */
#ifndef CLIB_MARCH_VARIANT
int
syn_filter_enable_disable (u32 sw_if_index, int enable_disable)
{
vnet_main_t *vnm = vnet_get_main ();
vnet_sw_interface_t *sw;
int rv = 0;
/* Utterly wrong? */
if (pool_is_free_index (vnm->interface_main.sw_interfaces, sw_if_index))
return VNET_API_ERROR_INVALID_SW_IF_INDEX;
/* Not a physical port? */
sw = vnet_get_sw_interface (vnm, sw_if_index);
if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
return VNET_API_ERROR_INVALID_SW_IF_INDEX;
if (enable_disable)
{
syn_filter4_runtime_t *rt;
/* *INDENT-OFF* */
foreach_vlib_main ({
rt = vlib_node_get_runtime_data (this_vlib_main, syn_filter4_node.index);
vec_validate (rt->syn_counts, 1023);
/*
* Given perfect disperson / optimal hashing results:
* Allow 128k (successful) syns/sec. 1024, buckets each of which
* absorb 128 syns before filtering. Reset table once a second.
* Reality bites, lets try resetting once every 100ms.
*/
rt->reset_interval = 0.1; /* reset interval in seconds */
});
/* *INDENT-ON* */
}
rv = vnet_feature_enable_disable ("ip4-local", "syn-filter-4",
sw_if_index, enable_disable, 0, 0);
return rv;
}
static clib_error_t *
syn_filter_enable_disable_command_fn (vlib_main_t * vm,
unformat_input_t * input,
vlib_cli_command_t * cmd)
{
vnet_main_t *vnm = vnet_get_main ();
u32 sw_if_index = ~0;
int enable_disable = 1;
int rv;
while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
{
if (unformat (input, "disable"))
enable_disable = 0;
else if (unformat (input, "%U", unformat_vnet_sw_interface,
vnm, &sw_if_index))
;
else
break;
}
if (sw_if_index == ~0)
return clib_error_return (0, "Please specify an interface...");
rv = syn_filter_enable_disable (sw_if_index, enable_disable);
switch (rv)
{
case 0:
break;
case VNET_API_ERROR_INVALID_SW_IF_INDEX:
return clib_error_return
(0, "Invalid interface, only works on physical ports");
break;
case VNET_API_ERROR_UNIMPLEMENTED:
return clib_error_return (0,
"Device driver doesn't support redirection");
break;
case VNET_API_ERROR_INVALID_VALUE:
return clib_error_return (0, "feature arc not found");
case VNET_API_ERROR_INVALID_VALUE_2:
return clib_error_return (0, "feature node not found");
default:
return clib_error_return (0, "syn_filter_enable_disable returned %d",
rv);
}
return 0;
}
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (sr_content_command, static) =
{
.path = "ip syn filter",
.short_help = "ip syn filter <interface-name> [disable]",
.function = syn_filter_enable_disable_command_fn,
};
/* *INDENT-ON* */
#endif /* CLIB_MARCH_VARIANT */
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
|