Commit 0f882002 authored by Ondrej Zajicek (work)'s avatar Ondrej Zajicek (work)
Browse files

BGP: Fix processing of IPv6 Flowspec 

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.
parent 53401bef

lib/flowspec.c

+50 −33
Original line number Diff line number Diff line
@@ -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);

  }

}

lib/flowspec.h

+8 −0
Original line number Diff line number Diff line
@@ -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

 */

lib/flowspec_test.c

+53 −1
Original line number Diff line number Diff line
@@ -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)");

proto/bgp/packets.c

+2 −10
Original line number Diff line number Diff line
@@ -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);

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