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|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* Development of this code funded by Astaro AG (http://www.astaro.com/)
*/
#include <asm/unaligned.h>
#include <linux/kernel.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <linux/sctp.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/sctp/sctp.h>
#include <net/tcp.h>
struct nft_exthdr {
u8 type;
u8 offset;
u8 len;
u8 op;
u8 dreg;
u8 sreg;
u8 flags;
};
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];
unsigned int offset = 0;
int err;
if (pkt->skb->protocol != htons(ETH_P_IPV6))
goto err;
err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
nft_reg_store8(dest, err >= 0);
return;
} else if (err < 0) {
goto err;
}
offset += priv->offset;
dest[priv->len / NFT_REG32_SIZE] = 0;
if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
goto err;
return;
err:
regs->verdict.code = NFT_BREAK;
}
/* find the offset to specified option.
*
* If target header is found, its offset is set in *offset and return option
* number. Otherwise, return negative error.
*
* If the first fragment doesn't contain the End of Options it is considered
* invalid.
*/
static int ipv4_find_option(struct net *net, struct sk_buff *skb,
unsigned int *offset, int target)
{
unsigned char optbuf[sizeof(struct ip_options) + 40];
struct ip_options *opt = (struct ip_options *)optbuf;
struct iphdr *iph, _iph;
unsigned int start;
bool found = false;
__be32 info;
int optlen;
iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
if (!iph)
return -EBADMSG;
start = sizeof(struct iphdr);
optlen = iph->ihl * 4 - (int)sizeof(struct iphdr);
if (optlen <= 0)
return -ENOENT;
memset(opt, 0, sizeof(struct ip_options));
/* Copy the options since __ip_options_compile() modifies
* the options.
*/
if (skb_copy_bits(skb, start, opt->__data, optlen))
return -EBADMSG;
opt->optlen = optlen;
if (__ip_options_compile(net, opt, NULL, &info))
return -EBADMSG;
switch (target) {
case IPOPT_SSRR:
case IPOPT_LSRR:
if (!opt->srr)
break;
found = target == IPOPT_SSRR ? opt->is_strictroute :
!opt->is_strictroute;
if (found)
*offset = opt->srr + start;
break;
case IPOPT_RR:
if (!opt->rr)
break;
*offset = opt->rr + start;
found = true;
break;
case IPOPT_RA:
if (!opt->router_alert)
break;
*offset = opt->router_alert + start;
found = true;
break;
default:
return -EOPNOTSUPP;
}
return found ? target : -ENOENT;
}
static void nft_exthdr_ipv4_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];
struct sk_buff *skb = pkt->skb;
unsigned int offset;
int err;
if (skb->protocol != htons(ETH_P_IP))
goto err;
err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type);
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
nft_reg_store8(dest, err >= 0);
return;
} else if (err < 0) {
goto err;
}
offset += priv->offset;
dest[priv->len / NFT_REG32_SIZE] = 0;
if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
goto err;
return;
err:
regs->verdict.code = NFT_BREAK;
}
static void *
nft_tcp_header_pointer(const struct nft_pktinfo *pkt,
unsigned int len, void *buffer, unsigned int *tcphdr_len)
{
struct tcphdr *tcph;
if (pkt->tprot != IPPROTO_TCP || pkt->fragoff)
return NULL;
tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt), sizeof(*tcph), buffer);
if (!tcph)
return NULL;
*tcphdr_len = __tcp_hdrlen(tcph);
if (*tcphdr_len < sizeof(*tcph) || *tcphdr_len > len)
return NULL;
return skb_header_pointer(pkt->skb, nft_thoff(pkt), *tcphdr_len, buffer);
}
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;
tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
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;
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
*dest = 1;
} else {
dest[priv->len / NFT_REG32_SIZE] = 0;
memcpy(dest, opt + offset, priv->len);
}
return;
}
err:
if (priv->flags & NFT_EXTHDR_F_PRESENT)
*dest = 0;
else
regs->verdict.code = NFT_BREAK;
}
static void nft_exthdr_tcp_set_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;
struct tcphdr *tcph;
u8 *opt;
tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
if (!tcph)
goto err;
opt = (u8 *)tcph;
for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
union {
__be16 v16;
__be32 v32;
} old, new;
optl = optlen(opt, i);
if (priv->type != opt[i])
continue;
if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
goto err;
if (skb_ensure_writable(pkt->skb,
nft_thoff(pkt) + i + priv->len))
goto err;
tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff,
&tcphdr_len);
if (!tcph)
goto err;
offset = i + priv->offset;
switch (priv->len) {
case 2:
old.v16 = get_unaligned((u16 *)(opt + offset));
new.v16 = (__force __be16)nft_reg_load16(
®s->data[priv->sreg]);
switch (priv->type) {
case TCPOPT_MSS:
/* increase can cause connection to stall */
if (ntohs(old.v16) <= ntohs(new.v16))
return;
break;
}
if (old.v16 == new.v16)
return;
put_unaligned(new.v16, (u16*)(opt + offset));
inet_proto_csum_replace2(&tcph->check, pkt->skb,
old.v16, new.v16, false);
break;
case 4:
new.v32 = regs->data[priv->sreg];
old.v32 = get_unaligned((u32 *)(opt + offset));
if (old.v32 == new.v32)
return;
put_unaligned(new.v32, (u32*)(opt + offset));
inet_proto_csum_replace4(&tcph->check, pkt->skb,
old.v32, new.v32, false);
break;
default:
WARN_ON_ONCE(1);
break;
}
return;
}
return;
err:
regs->verdict.code = NFT_BREAK;
}
static void nft_exthdr_tcp_strip_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, tcphdr_len, optl;
struct tcphdr *tcph;
u8 *opt;
tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
if (!tcph)
goto err;
if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))
goto drop;
opt = (u8 *)nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
if (!opt)
goto err;
for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
unsigned int j;
optl = optlen(opt, i);
if (priv->type != opt[i])
continue;
if (i + optl > tcphdr_len)
goto drop;
for (j = 0; j < optl; ++j) {
u16 n = TCPOPT_NOP;
u16 o = opt[i+j];
if ((i + j) % 2 == 0) {
o <<= 8;
n <<= 8;
}
inet_proto_csum_replace2(&tcph->check, pkt->skb, htons(o),
htons(n), false);
}
memset(opt + i, TCPOPT_NOP, optl);
return;
}
/* option not found, continue. This allows to do multiple
* option removals per rule.
*/
return;
err:
regs->verdict.code = NFT_BREAK;
return;
drop:
/* can't remove, no choice but to drop */
regs->verdict.code = NF_DROP;
}
static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
unsigned int offset = nft_thoff(pkt) + sizeof(struct sctphdr);
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 *dest = ®s->data[priv->dreg];
const struct sctp_chunkhdr *sch;
struct sctp_chunkhdr _sch;
if (pkt->tprot != IPPROTO_SCTP)
goto err;
do {
sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch);
if (!sch || !sch->length)
break;
if (sch->type == priv->type) {
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
nft_reg_store8(dest, true);
return;
}
if (priv->offset + priv->len > ntohs(sch->length) ||
offset + ntohs(sch->length) > pkt->skb->len)
break;
dest[priv->len / NFT_REG32_SIZE] = 0;
if (skb_copy_bits(pkt->skb, offset + priv->offset,
dest, priv->len) < 0)
break;
return;
}
offset += SCTP_PAD4(ntohs(sch->length));
} while (offset < pkt->skb->len);
err:
if (priv->flags & NFT_EXTHDR_F_PRESENT)
nft_reg_store8(dest, false);
else
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 },
[NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
[NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
[NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 },
[NFTA_EXTHDR_OP] = { .type = NLA_U32 },
[NFTA_EXTHDR_SREG] = { .type = NLA_U32 },
};
static int nft_exthdr_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
int err;
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);
if (err < 0)
return err;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
if (err < 0)
return err;
if (tb[NFTA_EXTHDR_FLAGS]) {
err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
if (err < 0)
return err;
if (flags & ~NFT_EXTHDR_F_PRESENT)
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->flags = flags;
priv->op = op;
return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG],
&priv->dreg, NULL, NFT_DATA_VALUE,
priv->len);
}
static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
int err;
if (!tb[NFTA_EXTHDR_SREG] ||
!tb[NFTA_EXTHDR_TYPE] ||
!tb[NFTA_EXTHDR_OFFSET] ||
!tb[NFTA_EXTHDR_LEN])
return -EINVAL;
if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS])
return -EINVAL;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
if (err < 0)
return err;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
if (err < 0)
return err;
if (offset < 2)
return -EOPNOTSUPP;
switch (len) {
case 2: break;
case 4: break;
default:
return -EOPNOTSUPP;
}
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->flags = flags;
priv->op = op;
return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg,
priv->len);
}
static int nft_exthdr_tcp_strip_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
if (tb[NFTA_EXTHDR_SREG] ||
tb[NFTA_EXTHDR_DREG] ||
tb[NFTA_EXTHDR_FLAGS] ||
tb[NFTA_EXTHDR_OFFSET] ||
tb[NFTA_EXTHDR_LEN])
return -EINVAL;
if (!tb[NFTA_EXTHDR_TYPE])
return -EINVAL;
priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
priv->op = NFT_EXTHDR_OP_TCPOPT;
return 0;
}
static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
int err = nft_exthdr_init(ctx, expr, tb);
if (err < 0)
return err;
switch (priv->type) {
case IPOPT_SSRR:
case IPOPT_LSRR:
case IPOPT_RR:
case IPOPT_RA:
break;
default:
return -EOPNOTSUPP;
}
return 0;
}
static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv)
{
if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
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:
return -1;
}
static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_exthdr *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
return -1;
return nft_exthdr_dump_common(skb, priv);
}
static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_exthdr *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg))
return -1;
return nft_exthdr_dump_common(skb, priv);
}
static int nft_exthdr_dump_strip(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_exthdr *priv = nft_expr_priv(expr);
return nft_exthdr_dump_common(skb, priv);
}
static bool nft_exthdr_reduce(struct nft_regs_track *track,
const struct nft_expr *expr)
{
const struct nft_exthdr *priv = nft_expr_priv(expr);
const struct nft_exthdr *exthdr;
if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
nft_reg_track_update(track, expr, priv->dreg, priv->len);
return false;
}
exthdr = nft_expr_priv(track->regs[priv->dreg].selector);
if (priv->type != exthdr->type ||
priv->op != exthdr->op ||
priv->flags != exthdr->flags ||
priv->offset != exthdr->offset ||
priv->len != exthdr->len) {
nft_reg_track_update(track, expr, priv->dreg, priv->len);
return false;
}
if (!track->regs[priv->dreg].bitwise)
return true;
return nft_expr_reduce_bitwise(track, expr);
}
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,
.reduce = nft_exthdr_reduce,
};
static const struct nft_expr_ops nft_exthdr_ipv4_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_ipv4_eval,
.init = nft_exthdr_ipv4_init,
.dump = nft_exthdr_dump,
.reduce = nft_exthdr_reduce,
};
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_tcp_eval,
.init = nft_exthdr_init,
.dump = nft_exthdr_dump,
.reduce = nft_exthdr_reduce,
};
static const struct nft_expr_ops nft_exthdr_tcp_set_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_tcp_set_eval,
.init = nft_exthdr_tcp_set_init,
.dump = nft_exthdr_dump_set,
.reduce = NFT_REDUCE_READONLY,
};
static const struct nft_expr_ops nft_exthdr_tcp_strip_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_tcp_strip_eval,
.init = nft_exthdr_tcp_strip_init,
.dump = nft_exthdr_dump_strip,
.reduce = NFT_REDUCE_READONLY,
};
static const struct nft_expr_ops nft_exthdr_sctp_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_sctp_eval,
.init = nft_exthdr_init,
.dump = nft_exthdr_dump,
.reduce = nft_exthdr_reduce,
};
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;
if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG])
return ERR_PTR(-EOPNOTSUPP);
op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP]));
switch (op) {
case NFT_EXTHDR_OP_TCPOPT:
if (tb[NFTA_EXTHDR_SREG])
return &nft_exthdr_tcp_set_ops;
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_tcp_ops;
return &nft_exthdr_tcp_strip_ops;
case NFT_EXTHDR_OP_IPV6:
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_ipv6_ops;
break;
case NFT_EXTHDR_OP_IPV4:
if (ctx->family != NFPROTO_IPV6) {
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_ipv4_ops;
}
break;
case NFT_EXTHDR_OP_SCTP:
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_sctp_ops;
break;
}
return ERR_PTR(-EOPNOTSUPP);
}
struct nft_expr_type nft_exthdr_type __read_mostly = {
.name = "exthdr",
.select_ops = nft_exthdr_select_ops,
.policy = nft_exthdr_policy,
.maxattr = NFTA_EXTHDR_MAX,
.owner = THIS_MODULE,
};
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