projects / mirror_ubuntu-zesty-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 0ac4f893 HW |
1 | /* |
| 2 | * Hop Limit modification target for ip6tables | |
| 3 | * Maciej Soltysiak <solt@dns.toxicfilms.tv> | |
| 4 | * Based on HW's TTL module | |
| 5 | * | |
| 6 | * This software is distributed under the terms of GNU GPL | |
| 7 | */ | |
| 8 | ||
| 9 | #include <linux/module.h> | |
| 10 | #include <linux/skbuff.h> | |
| 11 | #include <linux/ip.h> | |
| 12 | ||
| 13 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
| 14 | #include <linux/netfilter_ipv6/ip6t_HL.h> | |
| 15 | ||
| 16 | MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>"); | |
| 17 | MODULE_DESCRIPTION("IP tables Hop Limit modification module"); | |
| 18 | MODULE_LICENSE("GPL"); | |
| 19 | ||
| 20 | static unsigned int ip6t_hl_target(struct sk_buff **pskb, | |
| 21 | const struct net_device *in, | |
| 22 | const struct net_device *out, | |
| 23 | unsigned int hooknum, | |
| 24 | const void *targinfo, void *userinfo) | |
| 25 | { | |
| 26 | struct ipv6hdr *ip6h; | |
| 27 | const struct ip6t_HL_info *info = targinfo; | |
| 28 | u_int16_t diffs[2]; | |
| 29 | int new_hl; | |
| 30 | ||
| 31 | if (!skb_make_writable(pskb, (*pskb)->len)) | |
| 32 | return NF_DROP; | |
| 33 | ||
| 34 | ip6h = (*pskb)->nh.ipv6h; | |
| 35 | ||
| 36 | switch (info->mode) { | |
| 37 | case IP6T_HL_SET: | |
| 38 | new_hl = info->hop_limit; | |
| 39 | break; | |
| 40 | case IP6T_HL_INC: | |
| 41 | new_hl = ip6h->hop_limit + info->hop_limit; | |
| 42 | if (new_hl > 255) | |
| 43 | new_hl = 255; | |
| 44 | break; | |
| 45 | case IP6T_HL_DEC: | |
| 46 | new_hl = ip6h->hop_limit - info->hop_limit; | |
| 47 | if (new_hl < 0) | |
| 48 | new_hl = 0; | |
| 49 | break; | |
| 50 | default: | |
| 51 | new_hl = ip6h->hop_limit; | |
| 52 | break; | |
| 53 | } | |
| 54 | ||
| 55 | if (new_hl != ip6h->hop_limit) { | |
| 56 | diffs[0] = htons(((unsigned)ip6h->hop_limit) << 8) ^ 0xFFFF; | |
| 57 | ip6h->hop_limit = new_hl; | |
| 58 | diffs[1] = htons(((unsigned)ip6h->hop_limit) << 8); | |
| 59 | } | |
| 60 | ||
| 61 | return IP6T_CONTINUE; | |
| 62 | } | |
| 63 | ||
| 64 | static int ip6t_hl_checkentry(const char *tablename, | |
| 2e4e6a17 | 65 | const void *entry, |
| 0ac4f893 HW |
66 | void *targinfo, |
| 67 | unsigned int targinfosize, | |
| 68 | unsigned int hook_mask) | |
| 69 | { | |
| 70 | struct ip6t_HL_info *info = targinfo; | |
| 71 | ||
| 72 | if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_HL_info))) { | |
| 73 | printk(KERN_WARNING "ip6t_HL: targinfosize %u != %Zu\n", | |
| 74 | targinfosize, | |
| 75 | IP6T_ALIGN(sizeof(struct ip6t_HL_info))); | |
| 76 | return 0; | |
| 77 | } | |
| 78 | ||
| 79 | if (strcmp(tablename, "mangle")) { | |
| 80 | printk(KERN_WARNING "ip6t_HL: can only be called from " | |
| 81 | "\"mangle\" table, not \"%s\"\n", tablename); | |
| 82 | return 0; | |
| 83 | } | |
| 84 | ||
| 85 | if (info->mode > IP6T_HL_MAXMODE) { | |
| 86 | printk(KERN_WARNING "ip6t_HL: invalid or unknown Mode %u\n", | |
| 87 | info->mode); | |
| 88 | return 0; | |
| 89 | } | |
| 90 | ||
| 91 | if ((info->mode != IP6T_HL_SET) && (info->hop_limit == 0)) { | |
| 92 | printk(KERN_WARNING "ip6t_HL: increment/decrement doesn't " | |
| 93 | "make sense with value 0\n"); | |
| 94 | return 0; | |
| 95 | } | |
| 96 | ||
| 97 | return 1; | |
| 98 | } | |
| 99 | ||
| 100 | static struct ip6t_target ip6t_HL = { | |
| 101 | .name = "HL", | |
| 102 | .target = ip6t_hl_target, | |
| 103 | .checkentry = ip6t_hl_checkentry, | |
| 104 | .me = THIS_MODULE | |
| 105 | }; | |
| 106 | ||
| 107 | static int __init init(void) | |
| 108 | { | |
| 109 | return ip6t_register_target(&ip6t_HL); | |
| 110 | } | |
| 111 | ||
| 112 | static void __exit fini(void) | |
| 113 | { | |
| 114 | ip6t_unregister_target(&ip6t_HL); | |
| 115 | } | |
| 116 | ||
| 117 | module_init(init); | |
| 118 | module_exit(fini); |