OpenWrt – Blame information for rev 1
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Rev | Author | Line No. | Line |
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1 | office | 1 | From: Pablo Neira Ayuso <pablo@netfilter.org> |
2 | Date: Sat, 30 Dec 2017 22:41:46 +0100 |
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3 | Subject: [PATCH] netfilter: remove defensive check on malformed packets from |
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4 | raw sockets |
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5 | |||
6 | Users cannot forge malformed IPv4/IPv6 headers via raw sockets that they |
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7 | can inject into the stack. Specifically, not for IPv4 since 55888dfb6ba7 |
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8 | ("AF_RAW: Augment raw_send_hdrinc to expand skb to fit iphdr->ihl |
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9 | (v2)"). IPv6 raw sockets also ensure that packets have a well-formed |
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10 | IPv6 header available in the skbuff. |
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11 | |||
12 | At quick glance, br_netfilter also validates layer 3 headers and it |
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13 | drops malformed both IPv4 and IPv6 packets. |
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14 | |||
15 | Therefore, let's remove this defensive check all over the place. |
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16 | |||
17 | Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
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18 | --- |
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19 | |||
20 | --- a/net/ipv4/netfilter/iptable_filter.c |
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21 | +++ b/net/ipv4/netfilter/iptable_filter.c |
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22 | @@ -38,12 +38,6 @@ static unsigned int |
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23 | iptable_filter_hook(void *priv, struct sk_buff *skb, |
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24 | const struct nf_hook_state *state) |
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25 | { |
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26 | - if (state->hook == NF_INET_LOCAL_OUT && |
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27 | - (skb->len < sizeof(struct iphdr) || |
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28 | - ip_hdrlen(skb) < sizeof(struct iphdr))) |
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29 | - /* root is playing with raw sockets. */ |
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30 | - return NF_ACCEPT; |
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31 | - |
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32 | return ipt_do_table(skb, state, state->net->ipv4.iptable_filter); |
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33 | } |
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34 | |||
35 | --- a/net/ipv4/netfilter/iptable_mangle.c |
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36 | +++ b/net/ipv4/netfilter/iptable_mangle.c |
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37 | @@ -49,11 +49,6 @@ ipt_mangle_out(struct sk_buff *skb, cons |
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38 | u_int32_t mark; |
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39 | int err; |
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40 | |||
41 | - /* root is playing with raw sockets. */ |
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42 | - if (skb->len < sizeof(struct iphdr) || |
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43 | - ip_hdrlen(skb) < sizeof(struct iphdr)) |
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44 | - return NF_ACCEPT; |
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45 | - |
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46 | /* Save things which could affect route */ |
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47 | mark = skb->mark; |
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48 | iph = ip_hdr(skb); |
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49 | --- a/net/ipv4/netfilter/iptable_raw.c |
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50 | +++ b/net/ipv4/netfilter/iptable_raw.c |
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51 | @@ -26,12 +26,6 @@ static unsigned int |
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52 | iptable_raw_hook(void *priv, struct sk_buff *skb, |
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53 | const struct nf_hook_state *state) |
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54 | { |
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55 | - if (state->hook == NF_INET_LOCAL_OUT && |
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56 | - (skb->len < sizeof(struct iphdr) || |
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57 | - ip_hdrlen(skb) < sizeof(struct iphdr))) |
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58 | - /* root is playing with raw sockets. */ |
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59 | - return NF_ACCEPT; |
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60 | - |
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61 | return ipt_do_table(skb, state, state->net->ipv4.iptable_raw); |
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62 | } |
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63 | |||
64 | --- a/net/ipv4/netfilter/iptable_security.c |
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65 | +++ b/net/ipv4/netfilter/iptable_security.c |
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66 | @@ -43,12 +43,6 @@ static unsigned int |
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67 | iptable_security_hook(void *priv, struct sk_buff *skb, |
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68 | const struct nf_hook_state *state) |
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69 | { |
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70 | - if (state->hook == NF_INET_LOCAL_OUT && |
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71 | - (skb->len < sizeof(struct iphdr) || |
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72 | - ip_hdrlen(skb) < sizeof(struct iphdr))) |
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73 | - /* Somebody is playing with raw sockets. */ |
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74 | - return NF_ACCEPT; |
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75 | - |
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76 | return ipt_do_table(skb, state, state->net->ipv4.iptable_security); |
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77 | } |
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78 | |||
79 | --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c |
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80 | +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c |
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81 | @@ -154,11 +154,6 @@ static unsigned int ipv4_conntrack_local |
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82 | struct sk_buff *skb, |
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83 | const struct nf_hook_state *state) |
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84 | { |
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85 | - /* root is playing with raw sockets. */ |
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86 | - if (skb->len < sizeof(struct iphdr) || |
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87 | - ip_hdrlen(skb) < sizeof(struct iphdr)) |
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88 | - return NF_ACCEPT; |
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89 | - |
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90 | if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */ |
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91 | enum ip_conntrack_info ctinfo; |
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92 | struct nf_conn *tmpl; |
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93 | --- a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c |
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94 | +++ b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c |
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95 | @@ -355,11 +355,6 @@ nf_nat_ipv4_out(void *priv, struct sk_bu |
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96 | #endif |
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97 | unsigned int ret; |
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98 | |||
99 | - /* root is playing with raw sockets. */ |
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100 | - if (skb->len < sizeof(struct iphdr) || |
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101 | - ip_hdrlen(skb) < sizeof(struct iphdr)) |
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102 | - return NF_ACCEPT; |
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103 | - |
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104 | ret = nf_nat_ipv4_fn(priv, skb, state, do_chain); |
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105 | #ifdef CONFIG_XFRM |
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106 | if (ret != NF_DROP && ret != NF_STOLEN && |
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107 | @@ -395,11 +390,6 @@ nf_nat_ipv4_local_fn(void *priv, struct |
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108 | unsigned int ret; |
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109 | int err; |
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110 | |||
111 | - /* root is playing with raw sockets. */ |
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112 | - if (skb->len < sizeof(struct iphdr) || |
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113 | - ip_hdrlen(skb) < sizeof(struct iphdr)) |
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114 | - return NF_ACCEPT; |
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115 | - |
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116 | ret = nf_nat_ipv4_fn(priv, skb, state, do_chain); |
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117 | if (ret != NF_DROP && ret != NF_STOLEN && |
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118 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
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119 | --- a/net/ipv4/netfilter/nf_tables_ipv4.c |
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120 | +++ b/net/ipv4/netfilter/nf_tables_ipv4.c |
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121 | @@ -30,21 +30,6 @@ static unsigned int nft_do_chain_ipv4(vo |
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122 | return nft_do_chain(&pkt, priv); |
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123 | } |
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124 | |||
125 | -static unsigned int nft_ipv4_output(void *priv, |
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126 | - struct sk_buff *skb, |
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127 | - const struct nf_hook_state *state) |
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128 | -{ |
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129 | - if (unlikely(skb->len < sizeof(struct iphdr) || |
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130 | - ip_hdr(skb)->ihl < sizeof(struct iphdr) / 4)) { |
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131 | - if (net_ratelimit()) |
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132 | - pr_info("nf_tables_ipv4: ignoring short SOCK_RAW " |
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133 | - "packet\n"); |
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134 | - return NF_ACCEPT; |
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135 | - } |
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136 | - |
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137 | - return nft_do_chain_ipv4(priv, skb, state); |
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138 | -} |
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139 | - |
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140 | static struct nft_af_info nft_af_ipv4 __read_mostly = { |
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141 | .family = NFPROTO_IPV4, |
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142 | .nhooks = NF_INET_NUMHOOKS, |
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143 | @@ -91,7 +76,7 @@ static const struct nf_chain_type filter |
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144 | (1 << NF_INET_POST_ROUTING), |
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145 | .hooks = { |
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146 | [NF_INET_LOCAL_IN] = nft_do_chain_ipv4, |
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147 | - [NF_INET_LOCAL_OUT] = nft_ipv4_output, |
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148 | + [NF_INET_LOCAL_OUT] = nft_do_chain_ipv4, |
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149 | [NF_INET_FORWARD] = nft_do_chain_ipv4, |
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150 | [NF_INET_PRE_ROUTING] = nft_do_chain_ipv4, |
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151 | [NF_INET_POST_ROUTING] = nft_do_chain_ipv4, |
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152 | --- a/net/ipv4/netfilter/nft_chain_route_ipv4.c |
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153 | +++ b/net/ipv4/netfilter/nft_chain_route_ipv4.c |
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154 | @@ -33,11 +33,6 @@ static unsigned int nf_route_table_hook( |
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155 | const struct iphdr *iph; |
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156 | int err; |
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157 | |||
158 | - /* root is playing with raw sockets. */ |
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159 | - if (skb->len < sizeof(struct iphdr) || |
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160 | - ip_hdrlen(skb) < sizeof(struct iphdr)) |
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161 | - return NF_ACCEPT; |
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162 | - |
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163 | nft_set_pktinfo(&pkt, skb, state); |
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164 | nft_set_pktinfo_ipv4(&pkt, skb); |
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165 | |||
166 | --- a/net/ipv6/netfilter/ip6table_mangle.c |
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167 | +++ b/net/ipv6/netfilter/ip6table_mangle.c |
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168 | @@ -42,14 +42,6 @@ ip6t_mangle_out(struct sk_buff *skb, con |
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169 | u_int8_t hop_limit; |
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170 | u_int32_t flowlabel, mark; |
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171 | int err; |
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172 | -#if 0 |
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173 | - /* root is playing with raw sockets. */ |
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174 | - if (skb->len < sizeof(struct iphdr) || |
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175 | - ip_hdrlen(skb) < sizeof(struct iphdr)) { |
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176 | - net_warn_ratelimited("ip6t_hook: happy cracking\n"); |
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177 | - return NF_ACCEPT; |
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178 | - } |
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179 | -#endif |
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180 | |||
181 | /* save source/dest address, mark, hoplimit, flowlabel, priority, */ |
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182 | memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr)); |
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183 | --- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c |
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184 | +++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c |
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185 | @@ -176,11 +176,6 @@ static unsigned int ipv6_conntrack_local |
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186 | struct sk_buff *skb, |
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187 | const struct nf_hook_state *state) |
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188 | { |
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189 | - /* root is playing with raw sockets. */ |
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190 | - if (skb->len < sizeof(struct ipv6hdr)) { |
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191 | - net_notice_ratelimited("ipv6_conntrack_local: packet too short\n"); |
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192 | - return NF_ACCEPT; |
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193 | - } |
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194 | return nf_conntrack_in(state->net, PF_INET6, state->hook, skb); |
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195 | } |
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196 | |||
197 | --- a/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c |
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198 | +++ b/net/ipv6/netfilter/nf_nat_l3proto_ipv6.c |
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199 | @@ -372,10 +372,6 @@ nf_nat_ipv6_out(void *priv, struct sk_bu |
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200 | #endif |
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201 | unsigned int ret; |
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202 | |||
203 | - /* root is playing with raw sockets. */ |
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204 | - if (skb->len < sizeof(struct ipv6hdr)) |
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205 | - return NF_ACCEPT; |
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206 | - |
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207 | ret = nf_nat_ipv6_fn(priv, skb, state, do_chain); |
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208 | #ifdef CONFIG_XFRM |
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209 | if (ret != NF_DROP && ret != NF_STOLEN && |
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210 | @@ -411,10 +407,6 @@ nf_nat_ipv6_local_fn(void *priv, struct |
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211 | unsigned int ret; |
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212 | int err; |
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213 | |||
214 | - /* root is playing with raw sockets. */ |
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215 | - if (skb->len < sizeof(struct ipv6hdr)) |
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216 | - return NF_ACCEPT; |
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217 | - |
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218 | ret = nf_nat_ipv6_fn(priv, skb, state, do_chain); |
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219 | if (ret != NF_DROP && ret != NF_STOLEN && |
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220 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
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221 | --- a/net/ipv6/netfilter/nf_tables_ipv6.c |
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222 | +++ b/net/ipv6/netfilter/nf_tables_ipv6.c |
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223 | @@ -28,20 +28,6 @@ static unsigned int nft_do_chain_ipv6(vo |
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224 | return nft_do_chain(&pkt, priv); |
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225 | } |
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226 | |||
227 | -static unsigned int nft_ipv6_output(void *priv, |
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228 | - struct sk_buff *skb, |
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229 | - const struct nf_hook_state *state) |
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230 | -{ |
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231 | - if (unlikely(skb->len < sizeof(struct ipv6hdr))) { |
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232 | - if (net_ratelimit()) |
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233 | - pr_info("nf_tables_ipv6: ignoring short SOCK_RAW " |
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234 | - "packet\n"); |
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235 | - return NF_ACCEPT; |
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236 | - } |
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237 | - |
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238 | - return nft_do_chain_ipv6(priv, skb, state); |
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239 | -} |
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240 | - |
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241 | static struct nft_af_info nft_af_ipv6 __read_mostly = { |
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242 | .family = NFPROTO_IPV6, |
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243 | .nhooks = NF_INET_NUMHOOKS, |
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244 | @@ -88,7 +74,7 @@ static const struct nf_chain_type filter |
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245 | (1 << NF_INET_POST_ROUTING), |
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246 | .hooks = { |
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247 | [NF_INET_LOCAL_IN] = nft_do_chain_ipv6, |
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248 | - [NF_INET_LOCAL_OUT] = nft_ipv6_output, |
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249 | + [NF_INET_LOCAL_OUT] = nft_do_chain_ipv6, |
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250 | [NF_INET_FORWARD] = nft_do_chain_ipv6, |
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251 | [NF_INET_PRE_ROUTING] = nft_do_chain_ipv6, |
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252 | [NF_INET_POST_ROUTING] = nft_do_chain_ipv6, |
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253 | --- a/net/netfilter/nf_tables_inet.c |
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254 | +++ b/net/netfilter/nf_tables_inet.c |
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255 | @@ -38,38 +38,6 @@ static unsigned int nft_do_chain_inet(vo |
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256 | return nft_do_chain(&pkt, priv); |
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257 | } |
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258 | |||
259 | -static unsigned int nft_inet_output(void *priv, struct sk_buff *skb, |
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260 | - const struct nf_hook_state *state) |
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261 | -{ |
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262 | - struct nft_pktinfo pkt; |
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263 | - |
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264 | - nft_set_pktinfo(&pkt, skb, state); |
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265 | - |
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266 | - switch (state->pf) { |
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267 | - case NFPROTO_IPV4: |
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268 | - if (unlikely(skb->len < sizeof(struct iphdr) || |
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269 | - ip_hdr(skb)->ihl < sizeof(struct iphdr) / 4)) { |
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270 | - if (net_ratelimit()) |
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271 | - pr_info("ignoring short SOCK_RAW packet\n"); |
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272 | - return NF_ACCEPT; |
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273 | - } |
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274 | - nft_set_pktinfo_ipv4(&pkt, skb); |
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275 | - break; |
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276 | - case NFPROTO_IPV6: |
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277 | - if (unlikely(skb->len < sizeof(struct ipv6hdr))) { |
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278 | - if (net_ratelimit()) |
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279 | - pr_info("ignoring short SOCK_RAW packet\n"); |
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280 | - return NF_ACCEPT; |
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281 | - } |
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282 | - nft_set_pktinfo_ipv6(&pkt, skb); |
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283 | - break; |
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284 | - default: |
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285 | - break; |
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286 | - } |
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287 | - |
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288 | - return nft_do_chain(&pkt, priv); |
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289 | -} |
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290 | - |
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291 | static struct nft_af_info nft_af_inet __read_mostly = { |
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292 | .family = NFPROTO_INET, |
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293 | .nhooks = NF_INET_NUMHOOKS, |
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294 | @@ -116,7 +84,7 @@ static const struct nf_chain_type filter |
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295 | (1 << NF_INET_POST_ROUTING), |
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296 | .hooks = { |
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297 | [NF_INET_LOCAL_IN] = nft_do_chain_inet, |
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298 | - [NF_INET_LOCAL_OUT] = nft_inet_output, |
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299 | + [NF_INET_LOCAL_OUT] = nft_do_chain_inet, |
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300 | [NF_INET_FORWARD] = nft_do_chain_inet, |
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301 | [NF_INET_PRE_ROUTING] = nft_do_chain_inet, |
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302 | [NF_INET_POST_ROUTING] = nft_do_chain_inet, |