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Diffstat (limited to 'bgpd/bgp_flowspec_util.c')
| -rw-r--r-- | bgpd/bgp_flowspec_util.c | 458 |
1 files changed, 458 insertions, 0 deletions
diff --git a/bgpd/bgp_flowspec_util.c b/bgpd/bgp_flowspec_util.c new file mode 100644 index 0000000000..007b27f17e --- /dev/null +++ b/bgpd/bgp_flowspec_util.c @@ -0,0 +1,458 @@ +/* BGP FlowSpec Utilities + * Portions: + * Copyright (C) 2017 ChinaTelecom SDN Group + * Copyright (C) 2018 6WIND + * + * FRRouting is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * FRRouting is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; see the file COPYING; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "zebra.h" + +#include "prefix.h" + +#include "bgp_table.h" +#include "bgp_flowspec_util.h" +#include "bgp_flowspec_private.h" + +static void hex2bin(uint8_t *hex, int *bin) +{ + int remainder = *hex; + int i = 0; + + while (remainder >= 1 && i < 8) { + bin[7-i] = remainder % 2; + remainder = remainder / 2; + i++; + } + for (; i < 8; i++) + bin[7-i] = 0; +} + +static int hexstr2num(uint8_t *hexstr, int len) +{ + int i = 0; + int num = 0; + + for (i = 0; i < len; i++) + num = hexstr[i] + 16*16*num; + return num; +} + + +/* + * handle the flowspec address src/dst or generic address NLRI + * return number of bytes analysed ( >= 0). + */ +int bgp_flowspec_ip_address(enum bgp_flowspec_util_nlri_t type, + uint8_t *nlri_ptr, + uint32_t max_len, + void *result, int *error) +{ + char *display = (char *)result; /* for return_string */ + struct prefix *prefix = (struct prefix *)result; + uint32_t offset = 0; + struct prefix prefix_local; + int psize; + + *error = 0; + memset(&prefix_local, 0, sizeof(struct prefix)); + /* read the prefix length */ + prefix_local.prefixlen = nlri_ptr[offset]; + psize = PSIZE(prefix_local.prefixlen); + offset++; + /* TODO Flowspec IPv6 Support */ + prefix_local.family = AF_INET; + /* Prefix length check. */ + if (prefix_local.prefixlen > prefix_blen(&prefix_local) * 8) + *error = -1; + /* When packet overflow occur return immediately. */ + if (psize + offset > max_len) + *error = -1; + /* Defensive coding, double-check + * the psize fits in a struct prefix + */ + if (psize > (ssize_t)sizeof(prefix_local.u)) + *error = -1; + memcpy(&prefix_local.u.prefix, &nlri_ptr[offset], psize); + offset += psize; + switch (type) { + case BGP_FLOWSPEC_RETURN_STRING: + prefix2str(&prefix_local, display, + BGP_FLOWSPEC_STRING_DISPLAY_MAX); + break; + case BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE: + PREFIX_COPY_IPV4(prefix, &prefix_local) + break; + case BGP_FLOWSPEC_VALIDATE_ONLY: + default: + break; + } + return offset; +} + +/* + * handle the flowspec operator NLRI + * return number of bytes analysed + * if there is an error, the passed error param is used to give error: + * -1 if decoding error, + * if result is a string, its assumed length + * is BGP_FLOWSPEC_STRING_DISPLAY_MAX + */ +int bgp_flowspec_op_decode(enum bgp_flowspec_util_nlri_t type, + uint8_t *nlri_ptr, + uint32_t max_len, + void *result, int *error) +{ + int op[8]; + int len, value, value_size; + int loop = 0; + char *ptr = (char *)result; /* for return_string */ + uint32_t offset = 0; + int len_string = BGP_FLOWSPEC_STRING_DISPLAY_MAX; + int len_written; + + *error = 0; + do { + hex2bin(&nlri_ptr[offset], op); + offset++; + len = 2*op[2]+op[3]; + value_size = 1 << len; + value = hexstr2num(&nlri_ptr[offset], value_size); + /* can not be < and > at the same time */ + if (op[5] == 1 && op[6] == 1) + *error = -1; + /* if first element, AND bit can not be set */ + if (op[1] == 1 && loop == 0) + *error = -1; + switch (type) { + case BGP_FLOWSPEC_RETURN_STRING: + if (loop) { + len_written = snprintf(ptr, len_string, + ", "); + len_string -= len_written; + ptr += len_written; + } + if (op[5] == 1) { + len_written = snprintf(ptr, len_string, + "<"); + len_string -= len_written; + ptr += len_written; + } + if (op[6] == 1) { + len_written = snprintf(ptr, len_string, + ">"); + len_string -= len_written; + ptr += len_written; + } + if (op[7] == 1) { + len_written = snprintf(ptr, len_string, + "="); + len_string -= len_written; + ptr += len_written; + } + len_written = snprintf(ptr, len_string, + " %d ", value); + len_string -= len_written; + ptr += len_written; + break; + case BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE: + /* TODO : FS OPAQUE */ + break; + case BGP_FLOWSPEC_VALIDATE_ONLY: + default: + /* no action */ + break; + } + offset += value_size; + loop++; + } while (op[0] == 0 && offset < max_len - 1); + if (offset > max_len) + *error = -1; + /* use error parameter to count the number of entries */ + if (*error == 0) + *error = loop; + return offset; +} + + +/* + * handle the flowspec tcpflags field + * return number of bytes analysed + * if there is an error, the passed error param is used to give error: + * -1 if decoding error, + * if result is a string, its assumed length + * is BGP_FLOWSPEC_STRING_DISPLAY_MAX + */ +int bgp_flowspec_tcpflags_decode(enum bgp_flowspec_util_nlri_t type, + uint8_t *nlri_ptr, + uint32_t max_len, + void *result, int *error) +{ + int op[8]; + int len, value_size, loop = 0, value; + char *ptr = (char *)result; /* for return_string */ + uint32_t offset = 0; + int len_string = BGP_FLOWSPEC_STRING_DISPLAY_MAX; + int len_written; + + *error = 0; + do { + hex2bin(&nlri_ptr[offset], op); + /* if first element, AND bit can not be set */ + if (op[1] == 1 && loop == 0) + *error = -1; + offset++; + len = 2 * op[2] + op[3]; + value_size = 1 << len; + value = hexstr2num(&nlri_ptr[offset], value_size); + switch (type) { + case BGP_FLOWSPEC_RETURN_STRING: + if (op[1] == 1 && loop != 0) { + len_written = snprintf(ptr, len_string, + ", and "); + len_string -= len_written; + ptr += len_written; + } else if (op[1] == 0 && loop != 0) { + len_written = snprintf(ptr, len_string, + ", or "); + len_string -= len_written; + ptr += len_written; + } + len_written = snprintf(ptr, len_string, + "tcp flags is "); + len_string -= len_written; + ptr += len_written; + if (op[6] == 1) { + ptr += snprintf(ptr, len_string, + "not "); + len_string -= len_written; + ptr += len_written; + } + if (op[7] == 1) { + ptr += snprintf(ptr, len_string, + "exactly match "); + len_string -= len_written; + ptr += len_written; + } + ptr += snprintf(ptr, len_string, + "%d", value); + len_string -= len_written; + ptr += len_written; + break; + case BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE: + /* TODO : FS OPAQUE */ + break; + case BGP_FLOWSPEC_VALIDATE_ONLY: + default: + /* no action */ + break; + } + offset += value_size; + loop++; + } while (op[0] == 0 && offset < max_len - 1); + if (offset > max_len) + *error = -1; + /* use error parameter to count the number of entries */ + if (*error == 0) + *error = loop; + return offset; +} + +/* + * handle the flowspec fragment type field + * return error (returned values are invalid) or number of bytes analysed + * -1 if error in decoding + * >= 0 : number of bytes analysed (ok). + */ +int bgp_flowspec_fragment_type_decode(enum bgp_flowspec_util_nlri_t type, + uint8_t *nlri_ptr, + uint32_t max_len, + void *result, int *error) +{ + int op[8]; + int len, value, value_size, loop = 0; + char *ptr = (char *)result; /* for return_string */ + uint32_t offset = 0; + int len_string = BGP_FLOWSPEC_STRING_DISPLAY_MAX; + int len_written; + + *error = 0; + do { + hex2bin(&nlri_ptr[offset], op); + offset++; + len = 2 * op[2] + op[3]; + value_size = 1 << len; + value = hexstr2num(&nlri_ptr[offset], value_size); + if (value != 1 && value != 2 && value != 4 && value != 8) + *error = -1; + offset += value_size; + /* TODO : as per RFC5574 : first Fragment bits are Reserved + * does that mean that it is not possible + * to handle multiple occurences ? + * as of today, we only grab the first TCP fragment + */ + if (loop) { + *error = -2; + loop++; + continue; + } + switch (type) { + case BGP_FLOWSPEC_RETURN_STRING: + switch (value) { + case 1: + len_written = snprintf(ptr, len_string, + "dont-fragment"); + len_string -= len_written; + ptr += len_written; + break; + case 2: + len_written = snprintf(ptr, len_string, + "is-fragment"); + len_string -= len_written; + ptr += len_written; + break; + case 4: + len_written = snprintf(ptr, len_string, + "first-fragment"); + len_string -= len_written; + ptr += len_written; + break; + case 8: + len_written = snprintf(ptr, len_string, + "last-fragment"); + len_string -= len_written; + ptr += len_written; + break; + default: + {} + } + break; + case BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE: + /* TODO : FS OPAQUE */ + break; + case BGP_FLOWSPEC_VALIDATE_ONLY: + default: + /* no action */ + break; + } + loop++; + } while (op[0] == 0 && offset < max_len - 1); + if (offset > max_len) + *error = -1; + return offset; +} + + +static bool bgp_flowspec_contains_prefix(struct prefix *pfs, + struct prefix *input, + int prefix_check) +{ + uint32_t offset = 0; + int type; + int ret = 0, error = 0; + uint8_t *nlri_content = (uint8_t *)pfs->u.prefix_flowspec.ptr; + size_t len = pfs->u.prefix_flowspec.prefixlen; + struct prefix compare; + + error = 0; + while (offset < len-1 && error >= 0) { + type = nlri_content[offset]; + offset++; + switch (type) { + case FLOWSPEC_DEST_PREFIX: + case FLOWSPEC_SRC_PREFIX: + memset(&compare, 0, sizeof(struct prefix)); + ret = bgp_flowspec_ip_address( + BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE, + nlri_content+offset, + len - offset, + &compare, &error); + if (ret <= 0) + break; + if (prefix_check && + compare.prefixlen != input->prefixlen) + break; + if (compare.family != input->family) + break; + if ((input->family == AF_INET) && + IPV4_ADDR_SAME(&input->u.prefix4, + &compare.u.prefix4)) + return true; + if ((input->family == AF_INET6) && + IPV6_ADDR_SAME(&input->u.prefix6.s6_addr, + &compare.u.prefix6.s6_addr)) + return true; + break; + case FLOWSPEC_IP_PROTOCOL: + case FLOWSPEC_PORT: + case FLOWSPEC_DEST_PORT: + case FLOWSPEC_SRC_PORT: + case FLOWSPEC_ICMP_TYPE: + case FLOWSPEC_ICMP_CODE: + ret = bgp_flowspec_op_decode(BGP_FLOWSPEC_VALIDATE_ONLY, + nlri_content+offset, + len - offset, + NULL, &error); + break; + case FLOWSPEC_TCP_FLAGS: + ret = bgp_flowspec_tcpflags_decode( + BGP_FLOWSPEC_VALIDATE_ONLY, + nlri_content+offset, + len - offset, + NULL, &error); + break; + case FLOWSPEC_PKT_LEN: + case FLOWSPEC_DSCP: + ret = bgp_flowspec_op_decode( + BGP_FLOWSPEC_VALIDATE_ONLY, + nlri_content + offset, + len - offset, NULL, + &error); + break; + case FLOWSPEC_FRAGMENT: + ret = bgp_flowspec_fragment_type_decode( + BGP_FLOWSPEC_VALIDATE_ONLY, + nlri_content + offset, + len - offset, NULL, + &error); + break; + default: + error = -1; + break; + } + offset += ret; + } + return false; +} + +struct bgp_node *bgp_flowspec_get_match_per_ip(afi_t afi, + struct bgp_table *rib, + struct prefix *match, + int prefix_check) +{ + struct bgp_node *rn; + struct prefix *prefix; + + for (rn = bgp_table_top(rib); rn; rn = bgp_route_next(rn)) { + prefix = &rn->p; + + if (prefix->family != AF_FLOWSPEC) + continue; + + if (bgp_flowspec_contains_prefix(prefix, match, prefix_check)) + return rn; + } + return NULL; +} |