[NETFILTER]: x_tables: mark matches and targets __read_mostly
[linux-3.10.git] / net / netfilter / xt_sctp.c
1 #include <linux/module.h>
2 #include <linux/skbuff.h>
3 #include <net/ip.h>
4 #include <net/ipv6.h>
5 #include <linux/sctp.h>
6
7 #include <linux/netfilter/x_tables.h>
8 #include <linux/netfilter/xt_sctp.h>
9 #include <linux/netfilter_ipv4/ip_tables.h>
10 #include <linux/netfilter_ipv6/ip6_tables.h>
11
12 MODULE_LICENSE("GPL");
13 MODULE_AUTHOR("Kiran Kumar Immidi");
14 MODULE_DESCRIPTION("Match for SCTP protocol packets");
15 MODULE_ALIAS("ipt_sctp");
16
17 #ifdef DEBUG_SCTP
18 #define duprintf(format, args...) printk(format , ## args)
19 #else
20 #define duprintf(format, args...)
21 #endif
22
23 #define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
24                                               || (!!((invflag) & (option)) ^ (cond)))
25
26 static bool
27 match_flags(const struct xt_sctp_flag_info *flag_info,
28             const int flag_count,
29             u_int8_t chunktype,
30             u_int8_t chunkflags)
31 {
32         int i;
33
34         for (i = 0; i < flag_count; i++)
35                 if (flag_info[i].chunktype == chunktype)
36                         return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag;
37
38         return true;
39 }
40
41 static inline bool
42 match_packet(const struct sk_buff *skb,
43              unsigned int offset,
44              const u_int32_t *chunkmap,
45              int chunk_match_type,
46              const struct xt_sctp_flag_info *flag_info,
47              const int flag_count,
48              bool *hotdrop)
49 {
50         u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)];
51         sctp_chunkhdr_t _sch, *sch;
52
53 #ifdef DEBUG_SCTP
54         int i = 0;
55 #endif
56
57         if (chunk_match_type == SCTP_CHUNK_MATCH_ALL)
58                 SCTP_CHUNKMAP_COPY(chunkmapcopy, chunkmap);
59
60         do {
61                 sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
62                 if (sch == NULL || sch->length == 0) {
63                         duprintf("Dropping invalid SCTP packet.\n");
64                         *hotdrop = true;
65                         return false;
66                 }
67
68                 duprintf("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d\tflags: %x\n",
69                                 ++i, offset, sch->type, htons(sch->length), sch->flags);
70
71                 offset += (ntohs(sch->length) + 3) & ~3;
72
73                 duprintf("skb->len: %d\toffset: %d\n", skb->len, offset);
74
75                 if (SCTP_CHUNKMAP_IS_SET(chunkmap, sch->type)) {
76                         switch (chunk_match_type) {
77                         case SCTP_CHUNK_MATCH_ANY:
78                                 if (match_flags(flag_info, flag_count,
79                                         sch->type, sch->flags)) {
80                                         return true;
81                                 }
82                                 break;
83
84                         case SCTP_CHUNK_MATCH_ALL:
85                                 if (match_flags(flag_info, flag_count,
86                                     sch->type, sch->flags))
87                                         SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type);
88                                 break;
89
90                         case SCTP_CHUNK_MATCH_ONLY:
91                                 if (!match_flags(flag_info, flag_count,
92                                     sch->type, sch->flags))
93                                         return false;
94                                 break;
95                         }
96                 } else {
97                         switch (chunk_match_type) {
98                         case SCTP_CHUNK_MATCH_ONLY:
99                                 return false;
100                         }
101                 }
102         } while (offset < skb->len);
103
104         switch (chunk_match_type) {
105         case SCTP_CHUNK_MATCH_ALL:
106                 return SCTP_CHUNKMAP_IS_CLEAR(chunkmap);
107         case SCTP_CHUNK_MATCH_ANY:
108                 return false;
109         case SCTP_CHUNK_MATCH_ONLY:
110                 return true;
111         }
112
113         /* This will never be reached, but required to stop compiler whine */
114         return false;
115 }
116
117 static bool
118 match(const struct sk_buff *skb,
119       const struct net_device *in,
120       const struct net_device *out,
121       const struct xt_match *match,
122       const void *matchinfo,
123       int offset,
124       unsigned int protoff,
125       bool *hotdrop)
126 {
127         const struct xt_sctp_info *info = matchinfo;
128         sctp_sctphdr_t _sh, *sh;
129
130         if (offset) {
131                 duprintf("Dropping non-first fragment.. FIXME\n");
132                 return false;
133         }
134
135         sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
136         if (sh == NULL) {
137                 duprintf("Dropping evil TCP offset=0 tinygram.\n");
138                 *hotdrop = true;
139                 return false;
140         }
141         duprintf("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest));
142
143         return  SCCHECK(ntohs(sh->source) >= info->spts[0]
144                         && ntohs(sh->source) <= info->spts[1],
145                         XT_SCTP_SRC_PORTS, info->flags, info->invflags)
146                 && SCCHECK(ntohs(sh->dest) >= info->dpts[0]
147                         && ntohs(sh->dest) <= info->dpts[1],
148                         XT_SCTP_DEST_PORTS, info->flags, info->invflags)
149                 && SCCHECK(match_packet(skb, protoff + sizeof (sctp_sctphdr_t),
150                                         info->chunkmap, info->chunk_match_type,
151                                         info->flag_info, info->flag_count,
152                                         hotdrop),
153                            XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
154 }
155
156 static bool
157 checkentry(const char *tablename,
158            const void *inf,
159            const struct xt_match *match,
160            void *matchinfo,
161            unsigned int hook_mask)
162 {
163         const struct xt_sctp_info *info = matchinfo;
164
165         return !(info->flags & ~XT_SCTP_VALID_FLAGS)
166                 && !(info->invflags & ~XT_SCTP_VALID_FLAGS)
167                 && !(info->invflags & ~info->flags)
168                 && ((!(info->flags & XT_SCTP_CHUNK_TYPES)) ||
169                         (info->chunk_match_type &
170                                 (SCTP_CHUNK_MATCH_ALL
171                                 | SCTP_CHUNK_MATCH_ANY
172                                 | SCTP_CHUNK_MATCH_ONLY)));
173 }
174
175 static struct xt_match xt_sctp_match[] __read_mostly = {
176         {
177                 .name           = "sctp",
178                 .family         = AF_INET,
179                 .checkentry     = checkentry,
180                 .match          = match,
181                 .matchsize      = sizeof(struct xt_sctp_info),
182                 .proto          = IPPROTO_SCTP,
183                 .me             = THIS_MODULE
184         },
185         {
186                 .name           = "sctp",
187                 .family         = AF_INET6,
188                 .checkentry     = checkentry,
189                 .match          = match,
190                 .matchsize      = sizeof(struct xt_sctp_info),
191                 .proto          = IPPROTO_SCTP,
192                 .me             = THIS_MODULE
193         },
194 };
195
196 static int __init xt_sctp_init(void)
197 {
198         return xt_register_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
199 }
200
201 static void __exit xt_sctp_fini(void)
202 {
203         xt_unregister_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
204 }
205
206 module_init(xt_sctp_init);
207 module_exit(xt_sctp_fini);