Harald Welte | 9d810fd | 2005-08-13 13:56:26 -0700 | [diff] [blame^] | 1 | /* Kernel module to match connection tracking byte counter. |
| 2 | * GPL (C) 2002 Martin Devera (devik@cdi.cz). |
| 3 | * |
| 4 | * 2004-07-20 Harald Welte <laforge@netfilter.org> |
| 5 | * - reimplemented to use per-connection accounting counters |
| 6 | * - add functionality to match number of packets |
| 7 | * - add functionality to match average packet size |
| 8 | * - add support to match directions seperately |
| 9 | * |
| 10 | */ |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/skbuff.h> |
| 13 | #include <linux/netfilter_ipv4/ip_conntrack.h> |
| 14 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 15 | #include <linux/netfilter_ipv4/ipt_connbytes.h> |
| 16 | |
| 17 | #include <asm/div64.h> |
| 18 | #include <asm/bitops.h> |
| 19 | |
| 20 | MODULE_LICENSE("GPL"); |
| 21 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| 22 | MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection"); |
| 23 | |
| 24 | /* 64bit divisor, dividend and result. dynamic precision */ |
| 25 | static u_int64_t div64_64(u_int64_t divisor, u_int64_t dividend) |
| 26 | { |
| 27 | u_int64_t result = divisor; |
| 28 | |
| 29 | if (dividend > 0xffffffff) { |
| 30 | int first_bit = find_first_bit((unsigned long *) ÷nd, sizeof(dividend)); |
| 31 | /* calculate number of bits to shift. shift exactly enough |
| 32 | * bits to make dividend fit in 32bits. */ |
| 33 | int num_shift = (64 - 32 - first_bit); |
| 34 | /* first bit has to be < 32, since dividend was > 0xffffffff */ |
| 35 | result = result >> num_shift; |
| 36 | dividend = dividend >> num_shift; |
| 37 | } |
| 38 | |
| 39 | do_div(divisor, dividend); |
| 40 | |
| 41 | return divisor; |
| 42 | } |
| 43 | |
| 44 | static int |
| 45 | match(const struct sk_buff *skb, |
| 46 | const struct net_device *in, |
| 47 | const struct net_device *out, |
| 48 | const void *matchinfo, |
| 49 | int offset, |
| 50 | int *hotdrop) |
| 51 | { |
| 52 | const struct ipt_connbytes_info *sinfo = matchinfo; |
| 53 | enum ip_conntrack_info ctinfo; |
| 54 | struct ip_conntrack *ct; |
| 55 | u_int64_t what = 0; /* initialize to make gcc happy */ |
| 56 | |
| 57 | if (!(ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo))) |
| 58 | return 0; /* no match */ |
| 59 | |
| 60 | switch (sinfo->what) { |
| 61 | case IPT_CONNBYTES_WHAT_PKTS: |
| 62 | switch (sinfo->direction) { |
| 63 | case IPT_CONNBYTES_DIR_ORIGINAL: |
| 64 | what = ct->counters[IP_CT_DIR_ORIGINAL].packets; |
| 65 | break; |
| 66 | case IPT_CONNBYTES_DIR_REPLY: |
| 67 | what = ct->counters[IP_CT_DIR_REPLY].packets; |
| 68 | break; |
| 69 | case IPT_CONNBYTES_DIR_BOTH: |
| 70 | what = ct->counters[IP_CT_DIR_ORIGINAL].packets; |
| 71 | what += ct->counters[IP_CT_DIR_REPLY].packets; |
| 72 | break; |
| 73 | } |
| 74 | break; |
| 75 | case IPT_CONNBYTES_WHAT_BYTES: |
| 76 | switch (sinfo->direction) { |
| 77 | case IPT_CONNBYTES_DIR_ORIGINAL: |
| 78 | what = ct->counters[IP_CT_DIR_ORIGINAL].bytes; |
| 79 | break; |
| 80 | case IPT_CONNBYTES_DIR_REPLY: |
| 81 | what = ct->counters[IP_CT_DIR_REPLY].bytes; |
| 82 | break; |
| 83 | case IPT_CONNBYTES_DIR_BOTH: |
| 84 | what = ct->counters[IP_CT_DIR_ORIGINAL].bytes; |
| 85 | what += ct->counters[IP_CT_DIR_REPLY].bytes; |
| 86 | break; |
| 87 | } |
| 88 | break; |
| 89 | case IPT_CONNBYTES_WHAT_AVGPKT: |
| 90 | switch (sinfo->direction) { |
| 91 | case IPT_CONNBYTES_DIR_ORIGINAL: |
| 92 | what = div64_64(ct->counters[IP_CT_DIR_ORIGINAL].bytes, |
| 93 | ct->counters[IP_CT_DIR_ORIGINAL].packets); |
| 94 | break; |
| 95 | case IPT_CONNBYTES_DIR_REPLY: |
| 96 | what = div64_64(ct->counters[IP_CT_DIR_REPLY].bytes, |
| 97 | ct->counters[IP_CT_DIR_REPLY].packets); |
| 98 | break; |
| 99 | case IPT_CONNBYTES_DIR_BOTH: |
| 100 | { |
| 101 | u_int64_t bytes; |
| 102 | u_int64_t pkts; |
| 103 | bytes = ct->counters[IP_CT_DIR_ORIGINAL].bytes + |
| 104 | ct->counters[IP_CT_DIR_REPLY].bytes; |
| 105 | pkts = ct->counters[IP_CT_DIR_ORIGINAL].packets+ |
| 106 | ct->counters[IP_CT_DIR_REPLY].packets; |
| 107 | |
| 108 | /* FIXME_THEORETICAL: what to do if sum |
| 109 | * overflows ? */ |
| 110 | |
| 111 | what = div64_64(bytes, pkts); |
| 112 | } |
| 113 | break; |
| 114 | } |
| 115 | break; |
| 116 | } |
| 117 | |
| 118 | if (sinfo->count.to) |
| 119 | return (what <= sinfo->count.to && what >= sinfo->count.from); |
| 120 | else |
| 121 | return (what >= sinfo->count.from); |
| 122 | } |
| 123 | |
| 124 | static int check(const char *tablename, |
| 125 | const struct ipt_ip *ip, |
| 126 | void *matchinfo, |
| 127 | unsigned int matchsize, |
| 128 | unsigned int hook_mask) |
| 129 | { |
| 130 | const struct ipt_connbytes_info *sinfo = matchinfo; |
| 131 | |
| 132 | if (matchsize != IPT_ALIGN(sizeof(struct ipt_connbytes_info))) |
| 133 | return 0; |
| 134 | |
| 135 | if (sinfo->what != IPT_CONNBYTES_WHAT_PKTS && |
| 136 | sinfo->what != IPT_CONNBYTES_WHAT_BYTES && |
| 137 | sinfo->what != IPT_CONNBYTES_WHAT_AVGPKT) |
| 138 | return 0; |
| 139 | |
| 140 | if (sinfo->direction != IPT_CONNBYTES_DIR_ORIGINAL && |
| 141 | sinfo->direction != IPT_CONNBYTES_DIR_REPLY && |
| 142 | sinfo->direction != IPT_CONNBYTES_DIR_BOTH) |
| 143 | return 0; |
| 144 | |
| 145 | return 1; |
| 146 | } |
| 147 | |
| 148 | static struct ipt_match state_match = { |
| 149 | .name = "connbytes", |
| 150 | .match = &match, |
| 151 | .checkentry = &check, |
| 152 | .me = THIS_MODULE |
| 153 | }; |
| 154 | |
| 155 | static int __init init(void) |
| 156 | { |
| 157 | return ipt_register_match(&state_match); |
| 158 | } |
| 159 | |
| 160 | static void __exit fini(void) |
| 161 | { |
| 162 | ipt_unregister_match(&state_match); |
| 163 | } |
| 164 | |
| 165 | module_init(init); |
| 166 | module_exit(fini); |