cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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nft_osf.c (4312B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2#include <net/ip.h>
      3#include <net/tcp.h>
      4
      5#include <net/netfilter/nf_tables.h>
      6#include <linux/netfilter/nfnetlink_osf.h>
      7
      8struct nft_osf {
      9	u8			dreg;
     10	u8			ttl;
     11	u32			flags;
     12};
     13
     14static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
     15	[NFTA_OSF_DREG]		= { .type = NLA_U32 },
     16	[NFTA_OSF_TTL]		= { .type = NLA_U8 },
     17	[NFTA_OSF_FLAGS]	= { .type = NLA_U32 },
     18};
     19
     20static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
     21			 const struct nft_pktinfo *pkt)
     22{
     23	struct nft_osf *priv = nft_expr_priv(expr);
     24	u32 *dest = &regs->data[priv->dreg];
     25	struct sk_buff *skb = pkt->skb;
     26	char os_match[NFT_OSF_MAXGENRELEN + 1];
     27	const struct tcphdr *tcp;
     28	struct nf_osf_data data;
     29	struct tcphdr _tcph;
     30
     31	if (pkt->tprot != IPPROTO_TCP) {
     32		regs->verdict.code = NFT_BREAK;
     33		return;
     34	}
     35
     36	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
     37				 sizeof(struct tcphdr), &_tcph);
     38	if (!tcp) {
     39		regs->verdict.code = NFT_BREAK;
     40		return;
     41	}
     42	if (!tcp->syn) {
     43		regs->verdict.code = NFT_BREAK;
     44		return;
     45	}
     46
     47	if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) {
     48		strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
     49	} else {
     50		if (priv->flags & NFT_OSF_F_VERSION)
     51			snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s",
     52				 data.genre, data.version);
     53		else
     54			strlcpy(os_match, data.genre, NFT_OSF_MAXGENRELEN);
     55
     56		strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
     57	}
     58}
     59
     60static int nft_osf_init(const struct nft_ctx *ctx,
     61			const struct nft_expr *expr,
     62			const struct nlattr * const tb[])
     63{
     64	struct nft_osf *priv = nft_expr_priv(expr);
     65	u32 flags;
     66	int err;
     67	u8 ttl;
     68
     69	if (!tb[NFTA_OSF_DREG])
     70		return -EINVAL;
     71
     72	if (tb[NFTA_OSF_TTL]) {
     73		ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
     74		if (ttl > 2)
     75			return -EINVAL;
     76		priv->ttl = ttl;
     77	}
     78
     79	if (tb[NFTA_OSF_FLAGS]) {
     80		flags = ntohl(nla_get_be32(tb[NFTA_OSF_FLAGS]));
     81		if (flags != NFT_OSF_F_VERSION)
     82			return -EINVAL;
     83		priv->flags = flags;
     84	}
     85
     86	err = nft_parse_register_store(ctx, tb[NFTA_OSF_DREG], &priv->dreg,
     87				       NULL, NFT_DATA_VALUE,
     88				       NFT_OSF_MAXGENRELEN);
     89	if (err < 0)
     90		return err;
     91
     92	return 0;
     93}
     94
     95static int nft_osf_dump(struct sk_buff *skb, const struct nft_expr *expr)
     96{
     97	const struct nft_osf *priv = nft_expr_priv(expr);
     98
     99	if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
    100		goto nla_put_failure;
    101
    102	if (nla_put_be32(skb, NFTA_OSF_FLAGS, ntohl(priv->flags)))
    103		goto nla_put_failure;
    104
    105	if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
    106		goto nla_put_failure;
    107
    108	return 0;
    109
    110nla_put_failure:
    111	return -1;
    112}
    113
    114static int nft_osf_validate(const struct nft_ctx *ctx,
    115			    const struct nft_expr *expr,
    116			    const struct nft_data **data)
    117{
    118	return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
    119						    (1 << NF_INET_PRE_ROUTING) |
    120						    (1 << NF_INET_FORWARD));
    121}
    122
    123static bool nft_osf_reduce(struct nft_regs_track *track,
    124			   const struct nft_expr *expr)
    125{
    126	struct nft_osf *priv = nft_expr_priv(expr);
    127	struct nft_osf *osf;
    128
    129	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
    130		nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
    131		return false;
    132	}
    133
    134	osf = nft_expr_priv(track->regs[priv->dreg].selector);
    135	if (priv->flags != osf->flags ||
    136	    priv->ttl != osf->ttl) {
    137		nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
    138		return false;
    139	}
    140
    141	if (!track->regs[priv->dreg].bitwise)
    142		return true;
    143
    144	return false;
    145}
    146
    147static struct nft_expr_type nft_osf_type;
    148static const struct nft_expr_ops nft_osf_op = {
    149	.eval		= nft_osf_eval,
    150	.size		= NFT_EXPR_SIZE(sizeof(struct nft_osf)),
    151	.init		= nft_osf_init,
    152	.dump		= nft_osf_dump,
    153	.type		= &nft_osf_type,
    154	.validate	= nft_osf_validate,
    155	.reduce		= nft_osf_reduce,
    156};
    157
    158static struct nft_expr_type nft_osf_type __read_mostly = {
    159	.ops		= &nft_osf_op,
    160	.name		= "osf",
    161	.owner		= THIS_MODULE,
    162	.policy		= nft_osf_policy,
    163	.maxattr	= NFTA_OSF_MAX,
    164};
    165
    166static int __init nft_osf_module_init(void)
    167{
    168	return nft_register_expr(&nft_osf_type);
    169}
    170
    171static void __exit nft_osf_module_exit(void)
    172{
    173	return nft_unregister_expr(&nft_osf_type);
    174}
    175
    176module_init(nft_osf_module_init);
    177module_exit(nft_osf_module_exit);
    178
    179MODULE_LICENSE("GPL");
    180MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
    181MODULE_ALIAS_NFT_EXPR("osf");
    182MODULE_DESCRIPTION("nftables passive OS fingerprint support");