net/netfilter/ipvs/ip_vs_pe_sip.c

   1 #define KMSG_COMPONENT "IPVS"
   2 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
   3
   4 #include <linux/module.h>
   5 #include <linux/kernel.h>
   6
   7 #include <net/ip_vs.h>
   8 #include <net/netfilter/nf_conntrack.h>
   9 #include <linux/netfilter/nf_conntrack_sip.h>
  10
  11 #ifdef CONFIG_IP_VS_DEBUG
  12 static const char *ip_vs_dbg_callid(char *buf, size_t buf_len,
  13                                     const char *callid, size_t callid_len,
  14                                     int *idx)
  15 {
  16         size_t max_len = 64;
  17         size_t len = min3(max_len, callid_len, buf_len - *idx - 1);
  18         memcpy(buf + *idx, callid, len);
  19         buf[*idx+len] = '\0';
  20         *idx += len + 1;
  21         return buf + *idx - len;
  22 }
  23
  24 #define IP_VS_DEBUG_CALLID(callid, len)                                 \
  25         ip_vs_dbg_callid(ip_vs_dbg_buf, sizeof(ip_vs_dbg_buf),          \
  26                          callid, len, &ip_vs_dbg_idx)
  27 #endif
  28
  29 static int get_callid(const char *dptr, unsigned int dataoff,
  30                       unsigned int datalen,
  31                       unsigned int *matchoff, unsigned int *matchlen)
  32 {
  33         /* Find callid */
  34         while (1) {
  35                 int ret = ct_sip_get_header(NULL, dptr, dataoff, datalen,
  36                                             SIP_HDR_CALL_ID, matchoff,
  37                                             matchlen);
  38                 if (ret > 0)
  39                         break;
  40                 if (!ret)
  41                         return -EINVAL;
  42                 dataoff += *matchoff;
  43         }
  44
  45         /* Too large is useless */
  46         if (*matchlen > IP_VS_PEDATA_MAXLEN)
  47                 return -EINVAL;
  48
  49         /* SIP headers are always followed by a line terminator */
  50         if (*matchoff + *matchlen == datalen)
  51                 return -EINVAL;
  52
  53         /* RFC 2543 allows lines to be terminated with CR, LF or CRLF,
  54          * RFC 3261 allows only CRLF, we support both. */
  55         if (*(dptr + *matchoff + *matchlen) != '\r' &&
  56             *(dptr + *matchoff + *matchlen) != '\n')
  57                 return -EINVAL;
  58
  59         IP_VS_DBG_BUF(9, "SIP callid %s (%d bytes)\n",
  60                       IP_VS_DEBUG_CALLID(dptr + *matchoff, *matchlen),
  61                       *matchlen);
  62         return 0;
  63 }
  64
  65 static int
  66 ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
  67 {
  68         struct ip_vs_iphdr iph;
  69         unsigned int dataoff, datalen, matchoff, matchlen;
  70         const char *dptr;
  71         int retc;
  72
  73         retc = ip_vs_fill_iph_skb(p->af, skb, false, &iph);
  74
  75         /* Only useful with UDP */
  76         if (!retc || iph.protocol != IPPROTO_UDP)
  77                 return -EINVAL;
  78         /* todo: IPv6 fragments:
  79          *       I think this only should be done for the first fragment. /HS
  80          */
  81         dataoff = iph.len + sizeof(struct udphdr);
  82
  83         if (dataoff >= skb->len)
  84                 return -EINVAL;
  85         retc = skb_linearize(skb);
  86         if (retc < 0)
  87                 return retc;
  88         dptr = skb->data + dataoff;
  89         datalen = skb->len - dataoff;
  90
  91         if (get_callid(dptr, 0, datalen, &matchoff, &matchlen))
  92                 return -EINVAL;
  93
  94         /* N.B: pe_data is only set on success,
  95          * this allows fallback to the default persistence logic on failure
  96          */
  97         p->pe_data = kmemdup(dptr + matchoff, matchlen, GFP_ATOMIC);
  98         if (!p->pe_data)
  99                 return -ENOMEM;
 100
 101         p->pe_data_len = matchlen;
 102
 103         return 0;
 104 }
 105
 106 static bool ip_vs_sip_ct_match(const struct ip_vs_conn_param *p,
 107                                   struct ip_vs_conn *ct)
 108
 109 {
 110         bool ret = false;
 111
 112         if (ct->af == p->af &&
 113             ip_vs_addr_equal(p->af, p->caddr, &ct->caddr) &&
 114             /* protocol should only be IPPROTO_IP if
 115              * d_addr is a fwmark */
 116             ip_vs_addr_equal(p->protocol == IPPROTO_IP ? AF_UNSPEC : p->af,
 117                              p->vaddr, &ct->vaddr) &&
 118             ct->vport == p->vport &&
 119             ct->flags & IP_VS_CONN_F_TEMPLATE &&
 120             ct->protocol == p->protocol &&
 121             ct->pe_data && ct->pe_data_len == p->pe_data_len &&
 122             !memcmp(ct->pe_data, p->pe_data, p->pe_data_len))
 123                 ret = true;
 124
 125         IP_VS_DBG_BUF(9, "SIP template match %s %s->%s:%d %s\n",
 126                       ip_vs_proto_name(p->protocol),
 127                       IP_VS_DEBUG_CALLID(p->pe_data, p->pe_data_len),
 128                       IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
 129                       ret ? "hit" : "not hit");
 130
 131         return ret;
 132 }
 133
 134 static u32 ip_vs_sip_hashkey_raw(const struct ip_vs_conn_param *p,
 135                                  u32 initval, bool inverse)
 136 {
 137         return jhash(p->pe_data, p->pe_data_len, initval);
 138 }
 139
 140 static int ip_vs_sip_show_pe_data(const struct ip_vs_conn *cp, char *buf)
 141 {
 142         memcpy(buf, cp->pe_data, cp->pe_data_len);
 143         return cp->pe_data_len;
 144 }
 145
 146 static struct ip_vs_conn *
 147 ip_vs_sip_conn_out(struct ip_vs_service *svc,
 148                    struct ip_vs_dest *dest,
 149                    struct sk_buff *skb,
 150                    const struct ip_vs_iphdr *iph,
 151                    __be16 dport,
 152                    __be16 cport)
 153 {
 154         if (likely(iph->protocol == IPPROTO_UDP))
 155                 return ip_vs_new_conn_out(svc, dest, skb, iph, dport, cport);
 156         /* currently no need to handle other than UDP */
 157         return NULL;
 158 }
 159
 160 static struct ip_vs_pe ip_vs_sip_pe =
 161 {
 162         .name =                 "sip",
 163         .refcnt =               ATOMIC_INIT(0),
 164         .module =               THIS_MODULE,
 165         .n_list =               LIST_HEAD_INIT(ip_vs_sip_pe.n_list),
 166         .fill_param =           ip_vs_sip_fill_param,
 167         .ct_match =             ip_vs_sip_ct_match,
 168         .hashkey_raw =          ip_vs_sip_hashkey_raw,
 169         .show_pe_data =         ip_vs_sip_show_pe_data,
 170         .conn_out =             ip_vs_sip_conn_out,
 171 };
 172
 173 static int __init ip_vs_sip_init(void)
 174 {
 175         return register_ip_vs_pe(&ip_vs_sip_pe);
 176 }
 177
 178 static void __exit ip_vs_sip_cleanup(void)
 179 {
 180         unregister_ip_vs_pe(&ip_vs_sip_pe);
 181         synchronize_rcu();
 182 }
 183
 184 module_init(ip_vs_sip_init);
 185 module_exit(ip_vs_sip_cleanup);
 186 MODULE_LICENSE("GPL");