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