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BGP: Fix processing of IPv6 Flowspec

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During NLRI parsing of IPv6 Flowspec, dst prefix was not properly
extracted from NLRI, therefore a received flow was stored in a different
position in flowspec routing table, and was not reachable by command
'show route <flow>'.

Add proper prefix part accessors to flowspec code and use them from BGP
NLRI parsing code.

Thanks to Alex D. for the bugreport.
This commit is contained in:
Ondrej Zajicek (work) 2019-11-18 17:44:34 +01:00
parent 53401bef63
commit 0f88200247
4 changed files with 113 additions and 44 deletions
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83
lib/flowspec.c
View file

@ -112,7 +112,6 @@ get_value_length(const byte *op)
}
/*
* Flowspec iterators
*/
@ -245,6 +244,45 @@ flow6_next_part(const byte *pos, const byte *end)
}
/*
* Flowspec accessors
*/
static inline ip4_addr
flow_read_ip4(const byte *px, uint pxlen)
{
ip4_addr ip = IP4_NONE;
memcpy(&ip, px, BYTES(pxlen));
return ip4_ntoh(ip);
}
ip4_addr
flow_read_ip4_part(const byte *part)
{
return flow_read_ip4(part + 2, part[1]);
}
static inline ip6_addr
flow_read_ip6(const byte *px, uint pxlen, uint pxoffset)
{
uint floor_offset = BYTES(pxoffset - (pxoffset % 8));
uint ceil_len = BYTES(pxlen);
ip6_addr ip = IP6_NONE;
memcpy(((byte *) &ip) + floor_offset, px, ceil_len - floor_offset);
return ip6_ntoh(ip);
}
ip6_addr
flow_read_ip6_part(const byte *part)
{
return flow_read_ip6(part + 3, part[1], part[2]);
}
/*
* Flowspec validation
*/
@ -779,26 +817,6 @@ flow_builder_set_type(struct flow_builder *fb, enum flow_type type)
fb->this_type = type;
}
static ip4_addr
flow_read_ip4(const byte *px, uint pxlen)
{
ip4_addr ip = IP4_NONE;
memcpy(&ip, px, BYTES(pxlen));
return ip4_ntoh(ip);
}
static ip6_addr
flow_read_ip6(const byte *px, uint pxlen, uint pxoffset)
{
uint floor_offset = BYTES(pxoffset - (pxoffset % 8));
uint ceil_len = BYTES(pxlen);
ip6_addr ip = IP6_NONE;
memcpy(((byte *) &ip) + floor_offset, px, ceil_len - floor_offset);
return ip6_ntoh(ip);
}
static void
builder_write_parts(struct flow_builder *fb, byte *buf)
{
@ -831,9 +849,9 @@ flow_builder4_finalize(struct flow_builder *fb, linpool *lpool)
if (fb->parts[FLOW_TYPE_DST_PREFIX].length)
{
byte *p = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset + 1;
pxlen = *p++;
prefix = flow_read_ip4(p, pxlen);
byte *part = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset;
prefix = flow_read_ip4_part(part);
pxlen = part[1];
}
*f = NET_ADDR_FLOW4(prefix, pxlen, data_len);
@ -861,10 +879,9 @@ flow_builder6_finalize(struct flow_builder *fb, linpool *lpool)
if (fb->parts[FLOW_TYPE_DST_PREFIX].length)
{
byte *p = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset + 1;
pxlen = *p++;
uint pxoffset = *p++;
prefix = flow_read_ip6(p, pxlen, pxoffset);
byte *part = fb->data.data + fb->parts[FLOW_TYPE_DST_PREFIX].offset;
prefix = flow_read_ip6_part(part);
pxlen = part[1];
}
*n = NET_ADDR_FLOW6(prefix, pxlen, data_len);
@ -947,18 +964,18 @@ fragment_val_str(u8 val)
static void
net_format_flow_ip(buffer *b, const byte *part, int ipv6)
{
uint pxlen = *(part+1);
uint pxlen = part[1];
if (ipv6)
{
uint pxoffset = *(part+2);
uint pxoffset = part[2];
if (pxoffset)
buffer_print(b, "%I6/%u offset %u; ", flow_read_ip6(part+3,pxlen,pxoffset), pxlen, pxoffset);
buffer_print(b, "%I6/%u offset %u; ", flow_read_ip6_part(part), pxlen, pxoffset);
else
buffer_print(b, "%I6/%u; ", flow_read_ip6(part+3,pxlen,0), pxlen);
buffer_print(b, "%I6/%u; ", flow_read_ip6_part(part), pxlen);
}
else
{
buffer_print(b, "%I4/%u; ", flow_read_ip4(part+2,pxlen), pxlen);
buffer_print(b, "%I4/%u; ", flow_read_ip4_part(part), pxlen);
}
}

8
lib/flowspec.h
View file

@ -85,6 +85,14 @@ const byte *flow4_next_part(const byte *pos, const byte *end);
const byte *flow6_next_part(const byte *pos, const byte *end);
/*
* Flowspec accessors
*/
ip4_addr flow_read_ip4_part(const byte *part);
ip6_addr flow_read_ip6_part(const byte *part);
/*
* Flowspec Builder
*/

54
lib/flowspec_test.c
View file

@ -137,7 +137,7 @@ static int
t_iterators6(void)
{
net_addr_flow6 *f;
NET_ADDR_FLOW6_(f, ip6_build(0,0,0x12345678,0x9a000000), 64, ((byte[]) {
NET_ADDR_FLOW6_(f, ip6_build(0,0,0x12345678,0x9a000000), 0x68, ((byte[]) {
26, /* Length */
FLOW_TYPE_DST_PREFIX, 0x68, 0x40, 0x12, 0x34, 0x56, 0x78, 0x9a,
FLOW_TYPE_SRC_PREFIX, 0x08, 0x0, 0xc0,
@ -166,6 +166,56 @@ t_iterators6(void)
return 1;
}
static int
t_accessors4(void)
{
net_addr_flow4 *f;
NET_ADDR_FLOW4_(f, ip4_build(5,6,7,0), 24, ((byte[]) {
25, /* Length */
FLOW_TYPE_DST_PREFIX, 24, 5, 6, 7,
FLOW_TYPE_SRC_PREFIX, 32, 10, 11, 12, 13,
FLOW_TYPE_IP_PROTOCOL, 0x81, 0x06,
FLOW_TYPE_PORT, 0x03, 0x89, 0x45, 0x8b, 0x91, 0x1f, 0x90,
FLOW_TYPE_TCP_FLAGS, 0x80, 0x55,
}));
const byte *p1_dst_px = &f->data[1];
const ip4_addr p1_dst_addr = ip4_build(5,6,7,0);
const byte *p2_src_px = &f->data[6];
const ip4_addr p2_src_addr = ip4_build(10,11,12,13);
bt_assert(ip4_equal(flow_read_ip4_part(p1_dst_px), p1_dst_addr));
bt_assert(ip4_equal(flow_read_ip4_part(p2_src_px), p2_src_addr));
return 1;
}
static int
t_accessors6(void)
{
net_addr_flow6 *f;
NET_ADDR_FLOW6_(f, ip6_build(0,0,0x12345678,0x9a000000), 0x68, ((byte[]) {
26, /* Length */
FLOW_TYPE_DST_PREFIX, 0x68, 0x40, 0x12, 0x34, 0x56, 0x78, 0x9a,
FLOW_TYPE_SRC_PREFIX, 0x08, 0x0, 0xc0,
FLOW_TYPE_NEXT_HEADER, 0x81, 0x06,
FLOW_TYPE_PORT, 0x03, 0x89, 0x45, 0x8b, 0x91, 0x1f, 0x90,
FLOW_TYPE_LABEL, 0x80, 0x55,
}));
const byte *p1_dst_px = &f->data[1];
const ip6_addr p1_dst_addr = ip6_build(0,0,0x12345678,0x9a000000);
const byte *p2_src_px = &f->data[9];
const ip6_addr p2_src_addr = ip6_build(0xc0000000, 0, 0, 0);
bt_assert(ip6_equal(flow_read_ip6_part(p1_dst_px), p1_dst_addr));
bt_assert(ip6_equal(flow_read_ip6_part(p2_src_px), p2_src_addr));
return 1;
}
static int
t_validation4(void)
{
@ -628,6 +678,8 @@ main(int argc, char *argv[])
bt_test_suite(t_first_part, "Searching first part in net_addr_flow");
bt_test_suite(t_iterators4, "Testing iterators (IPv4)");
bt_test_suite(t_iterators6, "Testing iterators (IPv6)");
bt_test_suite(t_accessors4, "Testing accessors (IPv4)");
bt_test_suite(t_accessors6, "Testing accessors (IPv6)");
bt_test_suite(t_validation4, "Testing validation (IPv4)");
bt_test_suite(t_validation6, "Testing validation (IPv6)");
bt_test_suite(t_builder4, "Inserting components into existing Flow Specification (IPv4)");

12
proto/bgp/packets.c
View file

@ -1831,13 +1831,9 @@ bgp_decode_nlri_flow4(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
}
/* Decode dst prefix */
ip4_addr px = IP4_NONE;
ip4_addr px = flow_read_ip4_part(data);
uint pxlen = data[1];
// FIXME: Use some generic function
memcpy(&px, data+2, BYTES(pxlen));
px = ip4_and(ip4_ntoh(px), ip4_mkmask(pxlen));
/* Prepare the flow */
net_addr *n = alloca(sizeof(struct net_addr_flow4) + flen);
net_fill_flow4(n, px, pxlen, pos, flen);
@ -1923,13 +1919,9 @@ bgp_decode_nlri_flow6(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
}
/* Decode dst prefix */
ip6_addr px = IP6_NONE;
ip6_addr px = flow_read_ip6_part(data);
uint pxlen = data[1];
// FIXME: Use some generic function
memcpy(&px, data+2, BYTES(pxlen));
px = ip6_and(ip6_ntoh(px), ip6_mkmask(pxlen));
/* Prepare the flow */
net_addr *n = alloca(sizeof(struct net_addr_flow6) + flen);
net_fill_flow6(n, px, pxlen, pos, flen);