From 935b7f643018878bd9d4193eea8b575aff736b9b Mon Sep 17 00:00:00 2001 From: Manuel Messner Date: Tue, 7 Feb 2017 03:14:53 +0100 Subject: netfilter: nft_exthdr: add TCP option matching This patch implements the kernel side of the TCP option patch. Signed-off-by: Manuel Messner Reviewed-by: Florian Westphal Acked-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- net/netfilter/Kconfig | 4 +- net/netfilter/nft_exthdr.c | 119 ++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 108 insertions(+), 15 deletions(-) (limited to 'net/netfilter') diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index ea479ed433732..9b28864cc36a9 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -467,10 +467,10 @@ config NF_TABLES_NETDEV This option enables support for the "netdev" table. config NFT_EXTHDR - tristate "Netfilter nf_tables IPv6 exthdr module" + tristate "Netfilter nf_tables exthdr module" help This option adds the "exthdr" expression that you can use to match - IPv6 extension headers. + IPv6 extension headers and tcp options. config NFT_META tristate "Netfilter nf_tables meta module" diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index a89e5ab150dba..c308920b194cd 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -15,20 +15,29 @@ #include #include #include -// FIXME: -#include +#include struct nft_exthdr { u8 type; u8 offset; u8 len; + u8 op; enum nft_registers dreg:8; u8 flags; }; -static void nft_exthdr_eval(const struct nft_expr *expr, - struct nft_regs *regs, - const struct nft_pktinfo *pkt) +static unsigned int optlen(const u8 *opt, unsigned int offset) +{ + /* Beware zero-length options: make finite progress */ + if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0) + return 1; + else + return opt[offset + 1]; +} + +static void nft_exthdr_ipv6_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) { struct nft_exthdr *priv = nft_expr_priv(expr); u32 *dest = ®s->data[priv->dreg]; @@ -52,6 +61,53 @@ err: regs->verdict.code = NFT_BREAK; } +static void nft_exthdr_tcp_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE]; + struct nft_exthdr *priv = nft_expr_priv(expr); + unsigned int i, optl, tcphdr_len, offset; + u32 *dest = ®s->data[priv->dreg]; + struct tcphdr *tcph; + u8 *opt; + + if (!pkt->tprot_set || pkt->tprot != IPPROTO_TCP) + goto err; + + tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buff); + if (!tcph) + goto err; + + tcphdr_len = __tcp_hdrlen(tcph); + if (tcphdr_len < sizeof(*tcph)) + goto err; + + tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, tcphdr_len, buff); + if (!tcph) + goto err; + + opt = (u8 *)tcph; + for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) { + optl = optlen(opt, i); + + if (priv->type != opt[i]) + continue; + + if (i + optl > tcphdr_len || priv->len + priv->offset > optl) + goto err; + + offset = i + priv->offset; + dest[priv->len / NFT_REG32_SIZE] = 0; + memcpy(dest, opt + offset, priv->len); + + return; + } + +err: + regs->verdict.code = NFT_BREAK; +} + static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = { [NFTA_EXTHDR_DREG] = { .type = NLA_U32 }, [NFTA_EXTHDR_TYPE] = { .type = NLA_U8 }, @@ -65,13 +121,13 @@ static int nft_exthdr_init(const struct nft_ctx *ctx, const struct nlattr * const tb[]) { struct nft_exthdr *priv = nft_expr_priv(expr); - u32 offset, len, flags = 0; + u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6; int err; - if (tb[NFTA_EXTHDR_DREG] == NULL || - tb[NFTA_EXTHDR_TYPE] == NULL || - tb[NFTA_EXTHDR_OFFSET] == NULL || - tb[NFTA_EXTHDR_LEN] == NULL) + if (!tb[NFTA_EXTHDR_DREG] || + !tb[NFTA_EXTHDR_TYPE] || + !tb[NFTA_EXTHDR_OFFSET] || + !tb[NFTA_EXTHDR_LEN]) return -EINVAL; err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset); @@ -91,11 +147,18 @@ static int nft_exthdr_init(const struct nft_ctx *ctx, return -EINVAL; } + if (tb[NFTA_EXTHDR_OP]) { + err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op); + if (err < 0) + return err; + } + priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); priv->offset = offset; priv->len = len; priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]); priv->flags = flags; + priv->op = op; return nft_validate_register_store(ctx, priv->dreg, NULL, NFT_DATA_VALUE, priv->len); @@ -115,6 +178,8 @@ static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr) goto nla_put_failure; if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags))) goto nla_put_failure; + if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op))) + goto nla_put_failure; return 0; nla_put_failure: @@ -122,17 +187,45 @@ nla_put_failure: } static struct nft_expr_type nft_exthdr_type; -static const struct nft_expr_ops nft_exthdr_ops = { +static const struct nft_expr_ops nft_exthdr_ipv6_ops = { + .type = &nft_exthdr_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), + .eval = nft_exthdr_ipv6_eval, + .init = nft_exthdr_init, + .dump = nft_exthdr_dump, +}; + +static const struct nft_expr_ops nft_exthdr_tcp_ops = { .type = &nft_exthdr_type, .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), - .eval = nft_exthdr_eval, + .eval = nft_exthdr_tcp_eval, .init = nft_exthdr_init, .dump = nft_exthdr_dump, }; +static const struct nft_expr_ops * +nft_exthdr_select_ops(const struct nft_ctx *ctx, + const struct nlattr * const tb[]) +{ + u32 op; + + if (!tb[NFTA_EXTHDR_OP]) + return &nft_exthdr_ipv6_ops; + + op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP])); + switch (op) { + case NFT_EXTHDR_OP_TCPOPT: + return &nft_exthdr_tcp_ops; + case NFT_EXTHDR_OP_IPV6: + return &nft_exthdr_ipv6_ops; + } + + return ERR_PTR(-EOPNOTSUPP); +} + static struct nft_expr_type nft_exthdr_type __read_mostly = { .name = "exthdr", - .ops = &nft_exthdr_ops, + .select_ops = &nft_exthdr_select_ops, .policy = nft_exthdr_policy, .maxattr = NFTA_EXTHDR_MAX, .owner = THIS_MODULE, -- cgit v1.2.3