Patrick McHardy | 9651851 | 2013-10-14 11:00:02 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | * |
| 8 | * Development of this code funded by Astaro AG (http://www.astaro.com/) |
| 9 | */ |
| 10 | |
| 11 | #include <linux/kernel.h> |
| 12 | #include <linux/init.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/netlink.h> |
| 15 | #include <linux/netfilter.h> |
| 16 | #include <linux/netfilter/nf_tables.h> |
| 17 | #include <net/netfilter/nf_tables_core.h> |
| 18 | #include <net/netfilter/nf_tables.h> |
| 19 | |
| 20 | struct nft_payload { |
| 21 | enum nft_payload_bases base:8; |
| 22 | u8 offset; |
| 23 | u8 len; |
| 24 | enum nft_registers dreg:8; |
| 25 | }; |
| 26 | |
| 27 | static void nft_payload_eval(const struct nft_expr *expr, |
| 28 | struct nft_data data[NFT_REG_MAX + 1], |
| 29 | const struct nft_pktinfo *pkt) |
| 30 | { |
| 31 | const struct nft_payload *priv = nft_expr_priv(expr); |
| 32 | const struct sk_buff *skb = pkt->skb; |
| 33 | struct nft_data *dest = &data[priv->dreg]; |
| 34 | int offset; |
| 35 | |
| 36 | switch (priv->base) { |
| 37 | case NFT_PAYLOAD_LL_HEADER: |
| 38 | if (!skb_mac_header_was_set(skb)) |
| 39 | goto err; |
| 40 | offset = skb_mac_header(skb) - skb->data; |
| 41 | break; |
| 42 | case NFT_PAYLOAD_NETWORK_HEADER: |
| 43 | offset = skb_network_offset(skb); |
| 44 | break; |
| 45 | case NFT_PAYLOAD_TRANSPORT_HEADER: |
| 46 | offset = skb_transport_offset(skb); |
| 47 | break; |
| 48 | default: |
| 49 | BUG(); |
| 50 | } |
| 51 | offset += priv->offset; |
| 52 | |
| 53 | if (skb_copy_bits(skb, offset, dest->data, priv->len) < 0) |
| 54 | goto err; |
| 55 | return; |
| 56 | err: |
| 57 | data[NFT_REG_VERDICT].verdict = NFT_BREAK; |
| 58 | } |
| 59 | |
| 60 | static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = { |
| 61 | [NFTA_PAYLOAD_DREG] = { .type = NLA_U32 }, |
| 62 | [NFTA_PAYLOAD_BASE] = { .type = NLA_U32 }, |
| 63 | [NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 }, |
| 64 | [NFTA_PAYLOAD_LEN] = { .type = NLA_U32 }, |
| 65 | }; |
| 66 | |
| 67 | static int nft_payload_init(const struct nft_ctx *ctx, |
| 68 | const struct nft_expr *expr, |
| 69 | const struct nlattr * const tb[]) |
| 70 | { |
| 71 | struct nft_payload *priv = nft_expr_priv(expr); |
| 72 | int err; |
| 73 | |
| 74 | if (tb[NFTA_PAYLOAD_DREG] == NULL || |
| 75 | tb[NFTA_PAYLOAD_BASE] == NULL || |
| 76 | tb[NFTA_PAYLOAD_OFFSET] == NULL || |
| 77 | tb[NFTA_PAYLOAD_LEN] == NULL) |
| 78 | return -EINVAL; |
| 79 | |
| 80 | priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE])); |
| 81 | switch (priv->base) { |
| 82 | case NFT_PAYLOAD_LL_HEADER: |
| 83 | case NFT_PAYLOAD_NETWORK_HEADER: |
| 84 | case NFT_PAYLOAD_TRANSPORT_HEADER: |
| 85 | break; |
| 86 | default: |
| 87 | return -EOPNOTSUPP; |
| 88 | } |
| 89 | |
| 90 | priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET])); |
| 91 | priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN])); |
| 92 | if (priv->len == 0 || |
| 93 | priv->len > FIELD_SIZEOF(struct nft_data, data)) |
| 94 | return -EINVAL; |
| 95 | |
| 96 | priv->dreg = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_DREG])); |
| 97 | err = nft_validate_output_register(priv->dreg); |
| 98 | if (err < 0) |
| 99 | return err; |
| 100 | return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE); |
| 101 | } |
| 102 | |
| 103 | static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr) |
| 104 | { |
| 105 | const struct nft_payload *priv = nft_expr_priv(expr); |
| 106 | |
| 107 | if (nla_put_be32(skb, NFTA_PAYLOAD_DREG, htonl(priv->dreg)) || |
| 108 | nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) || |
| 109 | nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) || |
| 110 | nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len))) |
| 111 | goto nla_put_failure; |
| 112 | return 0; |
| 113 | |
| 114 | nla_put_failure: |
| 115 | return -1; |
| 116 | } |
| 117 | |
| 118 | static struct nft_expr_ops nft_payload_ops __read_mostly = { |
| 119 | .name = "payload", |
| 120 | .size = NFT_EXPR_SIZE(sizeof(struct nft_payload)), |
| 121 | .owner = THIS_MODULE, |
| 122 | .eval = nft_payload_eval, |
| 123 | .init = nft_payload_init, |
| 124 | .dump = nft_payload_dump, |
| 125 | .policy = nft_payload_policy, |
| 126 | .maxattr = NFTA_PAYLOAD_MAX, |
| 127 | }; |
| 128 | |
| 129 | int __init nft_payload_module_init(void) |
| 130 | { |
| 131 | return nft_register_expr(&nft_payload_ops); |
| 132 | } |
| 133 | |
| 134 | void nft_payload_module_exit(void) |
| 135 | { |
| 136 | nft_unregister_expr(&nft_payload_ops); |
| 137 | } |