From 6c47260250fc6114ce2012db13e1cd3938a27b73 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 3 Sep 2018 18:09:40 +0200 Subject: [PATCH] netfilter: nf_tables: add xfrm expression MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit supports fetching saddr/daddr of tunnel mode states, request id and spi. If direction is 'in', use inbound skb secpath, else dst->xfrm. Joint work with Máté Eckl. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_tables.h | 29 +++ net/netfilter/Kconfig | 7 + net/netfilter/Makefile | 1 + net/netfilter/nft_xfrm.c | 293 +++++++++++++++++++++++ 4 files changed, 330 insertions(+) create mode 100644 net/netfilter/nft_xfrm.c diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 6c44cbbb2cda..702e4f0bec56 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1514,6 +1514,35 @@ enum nft_devices_attributes { }; #define NFTA_DEVICE_MAX (__NFTA_DEVICE_MAX - 1) +/* + * enum nft_xfrm_attributes - nf_tables xfrm expr netlink attributes + * + * @NFTA_XFRM_DREG: destination register (NLA_U32) + * @NFTA_XFRM_KEY: enum nft_xfrm_keys (NLA_U32) + * @NFTA_XFRM_DIR: direction (NLA_U8) + * @NFTA_XFRM_SPNUM: index in secpath array (NLA_U32) + */ +enum nft_xfrm_attributes { + NFTA_XFRM_UNSPEC, + NFTA_XFRM_DREG, + NFTA_XFRM_KEY, + NFTA_XFRM_DIR, + NFTA_XFRM_SPNUM, + __NFTA_XFRM_MAX +}; +#define NFTA_XFRM_MAX (__NFTA_XFRM_MAX - 1) + +enum nft_xfrm_keys { + NFT_XFRM_KEY_UNSPEC, + NFT_XFRM_KEY_DADDR_IP4, + NFT_XFRM_KEY_DADDR_IP6, + NFT_XFRM_KEY_SADDR_IP4, + NFT_XFRM_KEY_SADDR_IP6, + NFT_XFRM_KEY_REQID, + NFT_XFRM_KEY_SPI, + __NFT_XFRM_KEY_MAX, +}; +#define NFT_XFRM_KEY_MAX (__NFT_XFRM_KEY_MAX - 1) /** * enum nft_trace_attributes - nf_tables trace netlink attributes diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index f61c306de1d0..2ab870ef233a 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -625,6 +625,13 @@ config NFT_FIB_INET The lookup will be delegated to the IPv4 or IPv6 FIB depending on the protocol of the packet. +config NFT_XFRM + tristate "Netfilter nf_tables xfrm/IPSec security association matching" + depends on XFRM + help + This option adds an expression that you can use to extract properties + of a packets security association. + config NFT_SOCKET tristate "Netfilter nf_tables socket match support" depends on IPV6 || IPV6=n diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 16895e045b66..4ddf3ef51ece 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -113,6 +113,7 @@ obj-$(CONFIG_NFT_FIB_NETDEV) += nft_fib_netdev.o obj-$(CONFIG_NFT_SOCKET) += nft_socket.o obj-$(CONFIG_NFT_OSF) += nft_osf.o obj-$(CONFIG_NFT_TPROXY) += nft_tproxy.o +obj-$(CONFIG_NFT_XFRM) += nft_xfrm.o # nf_tables netdev obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o diff --git a/net/netfilter/nft_xfrm.c b/net/netfilter/nft_xfrm.c new file mode 100644 index 000000000000..3cf71a2e375b --- /dev/null +++ b/net/netfilter/nft_xfrm.c @@ -0,0 +1,293 @@ +/* + * 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. + * + * Generic part shared by ipv4 and ipv6 backends. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static const struct nla_policy nft_xfrm_policy[NFTA_XFRM_MAX + 1] = { + [NFTA_XFRM_KEY] = { .type = NLA_U32 }, + [NFTA_XFRM_DIR] = { .type = NLA_U8 }, + [NFTA_XFRM_SPNUM] = { .type = NLA_U32 }, + [NFTA_XFRM_DREG] = { .type = NLA_U32 }, +}; + +struct nft_xfrm { + enum nft_xfrm_keys key:8; + enum nft_registers dreg:8; + u8 dir; + u8 spnum; +}; + +static int nft_xfrm_get_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_xfrm *priv = nft_expr_priv(expr); + unsigned int len = 0; + u32 spnum = 0; + u8 dir; + + if (!tb[NFTA_XFRM_KEY] || !tb[NFTA_XFRM_DIR] || !tb[NFTA_XFRM_DREG]) + return -EINVAL; + + switch (ctx->family) { + case NFPROTO_IPV4: + case NFPROTO_IPV6: + case NFPROTO_INET: + break; + default: + return -EOPNOTSUPP; + } + + priv->key = ntohl(nla_get_u32(tb[NFTA_XFRM_KEY])); + switch (priv->key) { + case NFT_XFRM_KEY_REQID: + case NFT_XFRM_KEY_SPI: + len = sizeof(u32); + break; + case NFT_XFRM_KEY_DADDR_IP4: + case NFT_XFRM_KEY_SADDR_IP4: + len = sizeof(struct in_addr); + break; + case NFT_XFRM_KEY_DADDR_IP6: + case NFT_XFRM_KEY_SADDR_IP6: + len = sizeof(struct in6_addr); + break; + default: + return -EINVAL; + } + + dir = nla_get_u8(tb[NFTA_XFRM_DIR]); + switch (dir) { + case XFRM_POLICY_IN: + case XFRM_POLICY_OUT: + priv->dir = dir; + break; + default: + return -EINVAL; + } + + if (tb[NFTA_XFRM_SPNUM]) + spnum = ntohl(nla_get_be32(tb[NFTA_XFRM_SPNUM])); + + if (spnum >= XFRM_MAX_DEPTH) + return -ERANGE; + + priv->spnum = spnum; + + priv->dreg = nft_parse_register(tb[NFTA_XFRM_DREG]); + return nft_validate_register_store(ctx, priv->dreg, NULL, + NFT_DATA_VALUE, len); +} + +/* Return true if key asks for daddr/saddr and current + * state does have a valid address (BEET, TUNNEL). + */ +static bool xfrm_state_addr_ok(enum nft_xfrm_keys k, u8 family, u8 mode) +{ + switch (k) { + case NFT_XFRM_KEY_DADDR_IP4: + case NFT_XFRM_KEY_SADDR_IP4: + if (family == NFPROTO_IPV4) + break; + return false; + case NFT_XFRM_KEY_DADDR_IP6: + case NFT_XFRM_KEY_SADDR_IP6: + if (family == NFPROTO_IPV6) + break; + return false; + default: + return true; + } + + return mode == XFRM_MODE_BEET || mode == XFRM_MODE_TUNNEL; +} + +static void nft_xfrm_state_get_key(const struct nft_xfrm *priv, + struct nft_regs *regs, + const struct xfrm_state *state, + u8 family) +{ + u32 *dest = ®s->data[priv->dreg]; + + if (!xfrm_state_addr_ok(priv->key, family, state->props.mode)) { + regs->verdict.code = NFT_BREAK; + return; + } + + switch (priv->key) { + case NFT_XFRM_KEY_UNSPEC: + case __NFT_XFRM_KEY_MAX: + WARN_ON_ONCE(1); + break; + case NFT_XFRM_KEY_DADDR_IP4: + *dest = state->id.daddr.a4; + return; + case NFT_XFRM_KEY_DADDR_IP6: + memcpy(dest, &state->id.daddr.in6, sizeof(struct in6_addr)); + return; + case NFT_XFRM_KEY_SADDR_IP4: + *dest = state->props.saddr.a4; + return; + case NFT_XFRM_KEY_SADDR_IP6: + memcpy(dest, &state->props.saddr.in6, sizeof(struct in6_addr)); + return; + case NFT_XFRM_KEY_REQID: + *dest = state->props.reqid; + return; + case NFT_XFRM_KEY_SPI: + *dest = state->id.spi; + return; + } + + regs->verdict.code = NFT_BREAK; +} + +static void nft_xfrm_get_eval_in(const struct nft_xfrm *priv, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + const struct sec_path *sp = pkt->skb->sp; + const struct xfrm_state *state; + + if (sp == NULL || sp->len <= priv->spnum) { + regs->verdict.code = NFT_BREAK; + return; + } + + state = sp->xvec[priv->spnum]; + nft_xfrm_state_get_key(priv, regs, state, nft_pf(pkt)); +} + +static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + const struct dst_entry *dst = skb_dst(pkt->skb); + int i; + + for (i = 0; dst && dst->xfrm; + dst = ((const struct xfrm_dst *)dst)->child, i++) { + if (i < priv->spnum) + continue; + + nft_xfrm_state_get_key(priv, regs, dst->xfrm, nft_pf(pkt)); + return; + } + + regs->verdict.code = NFT_BREAK; +} + +static void nft_xfrm_get_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + const struct nft_xfrm *priv = nft_expr_priv(expr); + + switch (priv->dir) { + case XFRM_POLICY_IN: + nft_xfrm_get_eval_in(priv, regs, pkt); + break; + case XFRM_POLICY_OUT: + nft_xfrm_get_eval_out(priv, regs, pkt); + break; + default: + WARN_ON_ONCE(1); + regs->verdict.code = NFT_BREAK; + break; + } +} + +static int nft_xfrm_get_dump(struct sk_buff *skb, + const struct nft_expr *expr) +{ + const struct nft_xfrm *priv = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_XFRM_DREG, priv->dreg)) + return -1; + + if (nla_put_be32(skb, NFTA_XFRM_KEY, htonl(priv->key))) + return -1; + if (nla_put_u8(skb, NFTA_XFRM_DIR, priv->dir)) + return -1; + if (nla_put_be32(skb, NFTA_XFRM_SPNUM, htonl(priv->spnum))) + return -1; + + return 0; +} + +static int nft_xfrm_validate(const struct nft_ctx *ctx, const struct nft_expr *expr, + const struct nft_data **data) +{ + const struct nft_xfrm *priv = nft_expr_priv(expr); + unsigned int hooks; + + switch (priv->dir) { + case XFRM_POLICY_IN: + hooks = (1 << NF_INET_FORWARD) | + (1 << NF_INET_LOCAL_IN) | + (1 << NF_INET_PRE_ROUTING); + break; + case XFRM_POLICY_OUT: + hooks = (1 << NF_INET_FORWARD) | + (1 << NF_INET_LOCAL_OUT) | + (1 << NF_INET_POST_ROUTING); + break; + default: + WARN_ON_ONCE(1); + return -EINVAL; + } + + return nft_chain_validate_hooks(ctx->chain, hooks); +} + + +static struct nft_expr_type nft_xfrm_type; +static const struct nft_expr_ops nft_xfrm_get_ops = { + .type = &nft_xfrm_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_xfrm)), + .eval = nft_xfrm_get_eval, + .init = nft_xfrm_get_init, + .dump = nft_xfrm_get_dump, + .validate = nft_xfrm_validate, +}; + +static struct nft_expr_type nft_xfrm_type __read_mostly = { + .name = "xfrm", + .ops = &nft_xfrm_get_ops, + .policy = nft_xfrm_policy, + .maxattr = NFTA_XFRM_MAX, + .owner = THIS_MODULE, +}; + +static int __init nft_xfrm_module_init(void) +{ + return nft_register_expr(&nft_xfrm_type); +} + +static void __exit nft_xfrm_module_exit(void) +{ + nft_unregister_expr(&nft_xfrm_type); +} + +module_init(nft_xfrm_module_init); +module_exit(nft_xfrm_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("nf_tables: xfrm/IPSec matching"); +MODULE_AUTHOR("Florian Westphal "); +MODULE_AUTHOR("Máté Eckl "); +MODULE_ALIAS_NFT_EXPR("xfrm"); -- 2.30.2