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