netfilter: xtables: change xt_match.checkentry return type
[linux-2.6.git] / net / netfilter / xt_sctp.c
1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2 #include <linux/module.h>
3 #include <linux/skbuff.h>
4 #include <net/ip.h>
5 #include <net/ipv6.h>
6 #include <linux/sctp.h>
7
8 #include <linux/netfilter/x_tables.h>
9 #include <linux/netfilter/xt_sctp.h>
10 #include <linux/netfilter_ipv4/ip_tables.h>
11 #include <linux/netfilter_ipv6/ip6_tables.h>
12
13 MODULE_LICENSE("GPL");
14 MODULE_AUTHOR("Kiran Kumar Immidi");
15 MODULE_DESCRIPTION("Xtables: SCTP protocol packet match");
16 MODULE_ALIAS("ipt_sctp");
17 MODULE_ALIAS("ip6t_sctp");
18
19 #define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
20                                               || (!!((invflag) & (option)) ^ (cond)))
21
22 static bool
23 match_flags(const struct xt_sctp_flag_info *flag_info,
24             const int flag_count,
25             u_int8_t chunktype,
26             u_int8_t chunkflags)
27 {
28         int i;
29
30         for (i = 0; i < flag_count; i++)
31                 if (flag_info[i].chunktype == chunktype)
32                         return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag;
33
34         return true;
35 }
36
37 static inline bool
38 match_packet(const struct sk_buff *skb,
39              unsigned int offset,
40              const struct xt_sctp_info *info,
41              bool *hotdrop)
42 {
43         u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)];
44         const sctp_chunkhdr_t *sch;
45         sctp_chunkhdr_t _sch;
46         int chunk_match_type = info->chunk_match_type;
47         const struct xt_sctp_flag_info *flag_info = info->flag_info;
48         int flag_count = info->flag_count;
49
50 #ifdef DEBUG
51         int i = 0;
52 #endif
53
54         if (chunk_match_type == SCTP_CHUNK_MATCH_ALL)
55                 SCTP_CHUNKMAP_COPY(chunkmapcopy, info->chunkmap);
56
57         do {
58                 sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
59                 if (sch == NULL || sch->length == 0) {
60                         pr_debug("Dropping invalid SCTP packet.\n");
61                         *hotdrop = true;
62                         return false;
63                 }
64 #ifdef DEBUG
65                 pr_debug("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d"
66                          "\tflags: %x\n",
67                          ++i, offset, sch->type, htons(sch->length),
68                          sch->flags);
69 #endif
70                 offset += (ntohs(sch->length) + 3) & ~3;
71
72                 pr_debug("skb->len: %d\toffset: %d\n", skb->len, offset);
73
74                 if (SCTP_CHUNKMAP_IS_SET(info->chunkmap, sch->type)) {
75                         switch (chunk_match_type) {
76                         case SCTP_CHUNK_MATCH_ANY:
77                                 if (match_flags(flag_info, flag_count,
78                                         sch->type, sch->flags)) {
79                                         return true;
80                                 }
81                                 break;
82
83                         case SCTP_CHUNK_MATCH_ALL:
84                                 if (match_flags(flag_info, flag_count,
85                                     sch->type, sch->flags))
86                                         SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type);
87                                 break;
88
89                         case SCTP_CHUNK_MATCH_ONLY:
90                                 if (!match_flags(flag_info, flag_count,
91                                     sch->type, sch->flags))
92                                         return false;
93                                 break;
94                         }
95                 } else {
96                         switch (chunk_match_type) {
97                         case SCTP_CHUNK_MATCH_ONLY:
98                                 return false;
99                         }
100                 }
101         } while (offset < skb->len);
102
103         switch (chunk_match_type) {
104         case SCTP_CHUNK_MATCH_ALL:
105                 return SCTP_CHUNKMAP_IS_CLEAR(chunkmapcopy);
106         case SCTP_CHUNK_MATCH_ANY:
107                 return false;
108         case SCTP_CHUNK_MATCH_ONLY:
109                 return true;
110         }
111
112         /* This will never be reached, but required to stop compiler whine */
113         return false;
114 }
115
116 static bool
117 sctp_mt(const struct sk_buff *skb, const struct xt_match_param *par)
118 {
119         const struct xt_sctp_info *info = par->matchinfo;
120         const sctp_sctphdr_t *sh;
121         sctp_sctphdr_t _sh;
122
123         if (par->fragoff != 0) {
124                 pr_debug("Dropping non-first fragment.. FIXME\n");
125                 return false;
126         }
127
128         sh = skb_header_pointer(skb, par->thoff, sizeof(_sh), &_sh);
129         if (sh == NULL) {
130                 pr_debug("Dropping evil TCP offset=0 tinygram.\n");
131                 *par->hotdrop = true;
132                 return false;
133         }
134         pr_debug("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest));
135
136         return  SCCHECK(ntohs(sh->source) >= info->spts[0]
137                         && ntohs(sh->source) <= info->spts[1],
138                         XT_SCTP_SRC_PORTS, info->flags, info->invflags)
139                 && SCCHECK(ntohs(sh->dest) >= info->dpts[0]
140                         && ntohs(sh->dest) <= info->dpts[1],
141                         XT_SCTP_DEST_PORTS, info->flags, info->invflags)
142                 && SCCHECK(match_packet(skb, par->thoff + sizeof(sctp_sctphdr_t),
143                                         info, par->hotdrop),
144                            XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
145 }
146
147 static int sctp_mt_check(const struct xt_mtchk_param *par)
148 {
149         const struct xt_sctp_info *info = par->matchinfo;
150
151         if (info->flags & ~XT_SCTP_VALID_FLAGS)
152                 return false;
153         if (info->invflags & ~XT_SCTP_VALID_FLAGS)
154                 return false;
155         if (info->invflags & ~info->flags)
156                 return false;
157         if (!(info->flags & XT_SCTP_CHUNK_TYPES))
158                 return true;
159         if (info->chunk_match_type & (SCTP_CHUNK_MATCH_ALL |
160             SCTP_CHUNK_MATCH_ANY | SCTP_CHUNK_MATCH_ONLY))
161                 return true;
162         return false;
163 }
164
165 static struct xt_match sctp_mt_reg[] __read_mostly = {
166         {
167                 .name           = "sctp",
168                 .family         = NFPROTO_IPV4,
169                 .checkentry     = sctp_mt_check,
170                 .match          = sctp_mt,
171                 .matchsize      = sizeof(struct xt_sctp_info),
172                 .proto          = IPPROTO_SCTP,
173                 .me             = THIS_MODULE
174         },
175         {
176                 .name           = "sctp",
177                 .family         = NFPROTO_IPV6,
178                 .checkentry     = sctp_mt_check,
179                 .match          = sctp_mt,
180                 .matchsize      = sizeof(struct xt_sctp_info),
181                 .proto          = IPPROTO_SCTP,
182                 .me             = THIS_MODULE
183         },
184 };
185
186 static int __init sctp_mt_init(void)
187 {
188         return xt_register_matches(sctp_mt_reg, ARRAY_SIZE(sctp_mt_reg));
189 }
190
191 static void __exit sctp_mt_exit(void)
192 {
193         xt_unregister_matches(sctp_mt_reg, ARRAY_SIZE(sctp_mt_reg));
194 }
195
196 module_init(sctp_mt_init);
197 module_exit(sctp_mt_exit);