Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | #include <linux/module.h> |
| 2 | #include <linux/skbuff.h> |
| 3 | #include <net/ip.h> |
| 4 | #include <linux/sctp.h> |
| 5 | |
| 6 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 7 | #include <linux/netfilter_ipv4/ipt_sctp.h> |
| 8 | |
| 9 | #ifdef DEBUG_SCTP |
| 10 | #define duprintf(format, args...) printk(format , ## args) |
| 11 | #else |
| 12 | #define duprintf(format, args...) |
| 13 | #endif |
| 14 | |
| 15 | #define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ |
| 16 | || (!!((invflag) & (option)) ^ (cond))) |
| 17 | |
| 18 | static int |
| 19 | match_flags(const struct ipt_sctp_flag_info *flag_info, |
| 20 | const int flag_count, |
| 21 | u_int8_t chunktype, |
| 22 | u_int8_t chunkflags) |
| 23 | { |
| 24 | int i; |
| 25 | |
| 26 | for (i = 0; i < flag_count; i++) { |
| 27 | if (flag_info[i].chunktype == chunktype) { |
| 28 | return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag; |
| 29 | } |
| 30 | } |
| 31 | |
| 32 | return 1; |
| 33 | } |
| 34 | |
| 35 | static int |
| 36 | match_packet(const struct sk_buff *skb, |
| 37 | const u_int32_t *chunkmap, |
| 38 | int chunk_match_type, |
| 39 | const struct ipt_sctp_flag_info *flag_info, |
| 40 | const int flag_count, |
| 41 | int *hotdrop) |
| 42 | { |
| 43 | int offset; |
| 44 | u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)]; |
| 45 | sctp_chunkhdr_t _sch, *sch; |
| 46 | |
| 47 | #ifdef DEBUG_SCTP |
| 48 | int i = 0; |
| 49 | #endif |
| 50 | |
| 51 | if (chunk_match_type == SCTP_CHUNK_MATCH_ALL) { |
| 52 | SCTP_CHUNKMAP_COPY(chunkmapcopy, chunkmap); |
| 53 | } |
| 54 | |
| 55 | offset = skb->nh.iph->ihl * 4 + sizeof (sctp_sctphdr_t); |
| 56 | do { |
| 57 | sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch); |
| 58 | if (sch == NULL) { |
| 59 | duprintf("Dropping invalid SCTP packet.\n"); |
| 60 | *hotdrop = 1; |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | duprintf("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d\tflags: %x\n", |
| 65 | ++i, offset, sch->type, htons(sch->length), sch->flags); |
| 66 | |
| 67 | offset += (htons(sch->length) + 3) & ~3; |
| 68 | |
| 69 | duprintf("skb->len: %d\toffset: %d\n", skb->len, offset); |
| 70 | |
| 71 | if (SCTP_CHUNKMAP_IS_SET(chunkmap, sch->type)) { |
| 72 | switch (chunk_match_type) { |
| 73 | case SCTP_CHUNK_MATCH_ANY: |
| 74 | if (match_flags(flag_info, flag_count, |
| 75 | sch->type, sch->flags)) { |
| 76 | return 1; |
| 77 | } |
| 78 | break; |
| 79 | |
| 80 | case SCTP_CHUNK_MATCH_ALL: |
| 81 | if (match_flags(flag_info, flag_count, |
| 82 | sch->type, sch->flags)) { |
| 83 | SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type); |
| 84 | } |
| 85 | break; |
| 86 | |
| 87 | case SCTP_CHUNK_MATCH_ONLY: |
| 88 | if (!match_flags(flag_info, flag_count, |
| 89 | sch->type, sch->flags)) { |
| 90 | return 0; |
| 91 | } |
| 92 | break; |
| 93 | } |
| 94 | } else { |
| 95 | switch (chunk_match_type) { |
| 96 | case SCTP_CHUNK_MATCH_ONLY: |
| 97 | return 0; |
| 98 | } |
| 99 | } |
| 100 | } while (offset < skb->len); |
| 101 | |
| 102 | switch (chunk_match_type) { |
| 103 | case SCTP_CHUNK_MATCH_ALL: |
| 104 | return SCTP_CHUNKMAP_IS_CLEAR(chunkmap); |
| 105 | case SCTP_CHUNK_MATCH_ANY: |
| 106 | return 0; |
| 107 | case SCTP_CHUNK_MATCH_ONLY: |
| 108 | return 1; |
| 109 | } |
| 110 | |
| 111 | /* This will never be reached, but required to stop compiler whine */ |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | static int |
| 116 | match(const struct sk_buff *skb, |
| 117 | const struct net_device *in, |
| 118 | const struct net_device *out, |
| 119 | const void *matchinfo, |
| 120 | int offset, |
| 121 | int *hotdrop) |
| 122 | { |
| 123 | const struct ipt_sctp_info *info; |
| 124 | sctp_sctphdr_t _sh, *sh; |
| 125 | |
| 126 | info = (const struct ipt_sctp_info *)matchinfo; |
| 127 | |
| 128 | if (offset) { |
| 129 | duprintf("Dropping non-first fragment.. FIXME\n"); |
| 130 | return 0; |
| 131 | } |
| 132 | |
| 133 | sh = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_sh), &_sh); |
| 134 | if (sh == NULL) { |
| 135 | duprintf("Dropping evil TCP offset=0 tinygram.\n"); |
| 136 | *hotdrop = 1; |
| 137 | return 0; |
| 138 | } |
| 139 | duprintf("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest)); |
| 140 | |
| 141 | return SCCHECK(((ntohs(sh->source) >= info->spts[0]) |
| 142 | && (ntohs(sh->source) <= info->spts[1])), |
| 143 | IPT_SCTP_SRC_PORTS, info->flags, info->invflags) |
| 144 | && SCCHECK(((ntohs(sh->dest) >= info->dpts[0]) |
| 145 | && (ntohs(sh->dest) <= info->dpts[1])), |
| 146 | IPT_SCTP_DEST_PORTS, info->flags, info->invflags) |
| 147 | && SCCHECK(match_packet(skb, info->chunkmap, info->chunk_match_type, |
| 148 | info->flag_info, info->flag_count, |
| 149 | hotdrop), |
| 150 | IPT_SCTP_CHUNK_TYPES, info->flags, info->invflags); |
| 151 | } |
| 152 | |
| 153 | static int |
| 154 | checkentry(const char *tablename, |
| 155 | const struct ipt_ip *ip, |
| 156 | void *matchinfo, |
| 157 | unsigned int matchsize, |
| 158 | unsigned int hook_mask) |
| 159 | { |
| 160 | const struct ipt_sctp_info *info; |
| 161 | |
| 162 | info = (const struct ipt_sctp_info *)matchinfo; |
| 163 | |
| 164 | return ip->proto == IPPROTO_SCTP |
| 165 | && !(ip->invflags & IPT_INV_PROTO) |
| 166 | && matchsize == IPT_ALIGN(sizeof(struct ipt_sctp_info)) |
| 167 | && !(info->flags & ~IPT_SCTP_VALID_FLAGS) |
| 168 | && !(info->invflags & ~IPT_SCTP_VALID_FLAGS) |
| 169 | && !(info->invflags & ~info->flags) |
| 170 | && ((!(info->flags & IPT_SCTP_CHUNK_TYPES)) || |
| 171 | (info->chunk_match_type & |
| 172 | (SCTP_CHUNK_MATCH_ALL |
| 173 | | SCTP_CHUNK_MATCH_ANY |
| 174 | | SCTP_CHUNK_MATCH_ONLY))); |
| 175 | } |
| 176 | |
| 177 | static struct ipt_match sctp_match = |
| 178 | { |
| 179 | .list = { NULL, NULL}, |
| 180 | .name = "sctp", |
| 181 | .match = &match, |
| 182 | .checkentry = &checkentry, |
| 183 | .destroy = NULL, |
| 184 | .me = THIS_MODULE |
| 185 | }; |
| 186 | |
| 187 | static int __init init(void) |
| 188 | { |
| 189 | return ipt_register_match(&sctp_match); |
| 190 | } |
| 191 | |
| 192 | static void __exit fini(void) |
| 193 | { |
| 194 | ipt_unregister_match(&sctp_match); |
| 195 | } |
| 196 | |
| 197 | module_init(init); |
| 198 | module_exit(fini); |
| 199 | |
| 200 | MODULE_LICENSE("GPL"); |
| 201 | MODULE_AUTHOR("Kiran Kumar Immidi"); |
| 202 | MODULE_DESCRIPTION("Match for SCTP protocol packets"); |
| 203 | |