From 4a75ed32132d8e2292dd276f3ea7f4edec4f3d06 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 15 Sep 2016 17:28:00 +0200 Subject: src: add fib expression This adds the 'fib' expression which can be used to obtain the output interface from the route table based on either source or destination address of a packet. This can be used to e.g. add reverse path filtering: # drop if not coming from the same interface packet # arrived on # nft add rule x prerouting fib saddr . iif oif eq 0 drop # accept only if from eth0 # nft add rule x prerouting fib saddr . iif oif eq "eth0" accept # accept if from any valid interface # nft add rule x prerouting fib saddr oif accept Querying of address type is also supported. This can be used to e.g. only accept packets to addresses configured in the same interface: # fib daddr . iif type local Its also possible to use mark and verdict map, e.g.: # nft add rule x prerouting meta mark set 0xdead fib daddr . mark type vmap { blackhole : drop, prohibit : drop, unicast : accept } Signed-off-by: Florian Westphal --- src/fib.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 src/fib.c (limited to 'src/fib.c') diff --git a/src/fib.c b/src/fib.c new file mode 100644 index 00000000..346cce32 --- /dev/null +++ b/src/fib.c @@ -0,0 +1,144 @@ +/* + * FIB expression. + * + * Copyright (c) Red Hat GmbH. Author: Florian Westphal + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +static const char *fib_result[NFT_FIB_RESULT_MAX + 1] = { + [NFT_FIB_RESULT_OIF] = "oif", + [NFT_FIB_RESULT_OIFNAME] = "oifname", + [NFT_FIB_RESULT_ADDRTYPE] = "type", +}; + +static const struct symbol_table addrtype_tbl = { + .symbols = { + SYMBOL("unspec", RTN_UNSPEC), + SYMBOL("unicast", RTN_UNICAST), + SYMBOL("local", RTN_LOCAL), + SYMBOL("broadcast", RTN_BROADCAST), + SYMBOL("anycast", RTN_ANYCAST), + SYMBOL("multicast", RTN_MULTICAST), + SYMBOL("blackhole", RTN_BLACKHOLE), + SYMBOL("unreachable", RTN_UNREACHABLE), + SYMBOL("prohibit", RTN_PROHIBIT), + SYMBOL_LIST_END + } +}; + +static const struct datatype fib_addr_type = { + .type = TYPE_FIB_ADDR, + .name = "fib_addrtype", + .desc = "fib address type", + .byteorder = BYTEORDER_HOST_ENDIAN, + .size = 4 * BITS_PER_BYTE, + .basetype = &integer_type, + .sym_tbl = &addrtype_tbl, +}; + +static const char *fib_result_str(enum nft_fib_result result) +{ + if (result <= NFT_FIB_RESULT_MAX) + return fib_result[result]; + + return "unknown"; +} + +static void __fib_expr_print_f(unsigned int *flags, unsigned int f, const char *s) +{ + if ((*flags & f) == 0) + return; + + printf("%s", s); + *flags &= ~f; + if (*flags) + printf(" . "); +} + +static void fib_expr_print(const struct expr *expr) +{ + unsigned int flags = expr->fib.flags; + + printf("fib "); + __fib_expr_print_f(&flags, NFTA_FIB_F_SADDR, "saddr"); + __fib_expr_print_f(&flags, NFTA_FIB_F_DADDR, "daddr"); + __fib_expr_print_f(&flags, NFTA_FIB_F_MARK, "mark"); + __fib_expr_print_f(&flags, NFTA_FIB_F_IIF, "iif"); + __fib_expr_print_f(&flags, NFTA_FIB_F_OIF, "oif"); + + if (flags) + printf("0x%x", flags); + + printf(" %s", fib_result_str(expr->fib.result)); +} + +static bool fib_expr_cmp(const struct expr *e1, const struct expr *e2) +{ + return e1->fib.result == e2->fib.result && + e1->fib.flags == e2->fib.flags; +} + +static void fib_expr_clone(struct expr *new, const struct expr *expr) +{ + new->fib.result = expr->fib.result; + new->fib.flags= expr->fib.flags; +} + +static const struct expr_ops fib_expr_ops = { + .type = EXPR_FIB, + .name = "fib", + .print = fib_expr_print, + .cmp = fib_expr_cmp, + .clone = fib_expr_clone, +}; + +struct expr *fib_expr_alloc(const struct location *loc, + unsigned int flags, unsigned int result) +{ + const struct datatype *type; + unsigned int len = 4 * BITS_PER_BYTE; + struct expr *expr; + + switch (result) { + case NFT_FIB_RESULT_OIF: + type = &ifindex_type; + break; + case NFT_FIB_RESULT_OIFNAME: + type = &string_type; + len = IFNAMSIZ * BITS_PER_BYTE; + break; + case NFT_FIB_RESULT_ADDRTYPE: + type = &fib_addr_type; + break; + default: + BUG("Unknown result %d\n", result); + } + + expr = expr_alloc(loc, &fib_expr_ops, type, + BYTEORDER_HOST_ENDIAN, len); + + expr->fib.result = result; + expr->fib.flags = flags; + + return expr; +} + +static void __init fib_init(void) +{ + datatype_register(&fib_addr_type); +} -- cgit v1.2.3