[NETFILTER]: PPTP conntrack: consolidate header parsing

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 47 insertions, 72 deletions

diff --git a/net/ipv4/netfilter/ip_conntrack_helper_pptp.c b/net/ipv4/netfilter/ip_conntrack_helper_pptp.c
index 3b5464fa4217..9a98a6ce1901 100644
--- a/net/ipv4/netfilter/ip_conntrack_helper_pptp.c
+++ b/net/ipv4/netfilter/ip_conntrack_helper_pptp.c
@@ -291,60 +291,21 @@ out_unexpect_orig:
         goto out_put_both;
 }
 
-static const unsigned int pptp_msg_size[] = {
-        [PPTP_START_SESSION_REQUEST]  = sizeof(struct PptpStartSessionRequest),
-        [PPTP_START_SESSION_REPLY]    = sizeof(struct PptpStartSessionReply),
-        [PPTP_STOP_SESSION_REQUEST]   = sizeof(struct PptpStopSessionRequest),
-        [PPTP_STOP_SESSION_REPLY]     = sizeof(struct PptpStopSessionReply),
-        [PPTP_OUT_CALL_REQUEST]       = sizeof(struct PptpOutCallRequest),
-        [PPTP_OUT_CALL_REPLY]         = sizeof(struct PptpOutCallReply),
-        [PPTP_IN_CALL_REQUEST]        = sizeof(struct PptpInCallRequest),
-        [PPTP_IN_CALL_REPLY]          = sizeof(struct PptpInCallReply),
-        [PPTP_IN_CALL_CONNECT]        = sizeof(struct PptpInCallConnected),
-        [PPTP_CALL_CLEAR_REQUEST]     = sizeof(struct PptpClearCallRequest),
-        [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
-        [PPTP_WAN_ERROR_NOTIFY]       = sizeof(struct PptpWanErrorNotify),
-        [PPTP_SET_LINK_INFO]          = sizeof(struct PptpSetLinkInfo),
-};
-
 static inline int
 pptp_inbound_pkt(struct sk_buff **pskb,
-                 struct tcphdr *tcph,
-                 unsigned int nexthdr_off,
-                 unsigned int datalen,
+                 struct PptpControlHeader *ctlh,
+                 union pptp_ctrl_union *pptpReq,
+                 unsigned int reqlen,
                  struct ip_conntrack *ct,
                  enum ip_conntrack_info ctinfo)
 {
-        struct PptpControlHeader _ctlh, *ctlh;
-        unsigned int reqlen;
-        union pptp_ctrl_union _pptpReq, *pptpReq;
         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
         u_int16_t msg;
         __be16 cid, pcid;
 
-        ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
-        if (!ctlh) {
-                DEBUGP("error during skb_header_pointer\n");
-                return NF_ACCEPT;
-        }
-        nexthdr_off += sizeof(_ctlh);
-        datalen -= sizeof(_ctlh);
-
-        reqlen = datalen;
-        if (reqlen > sizeof(*pptpReq))
-                reqlen = sizeof(*pptpReq);
-        pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
-        if (!pptpReq) {
-                DEBUGP("error during skb_header_pointer\n");
-                return NF_ACCEPT;
-        }
-
         msg = ntohs(ctlh->messageType);
         DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
 
-        if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
-                return NF_ACCEPT;
-
         switch (msg) {
         case PPTP_START_SESSION_REPLY:
                 /* server confirms new control session */
@@ -480,38 +441,19 @@ pptp_inbound_pkt(struct sk_buff **pskb,
 
 static inline int
 pptp_outbound_pkt(struct sk_buff **pskb,
-                  struct tcphdr *tcph,
-                  unsigned int nexthdr_off,
-                  unsigned int datalen,
+                  struct PptpControlHeader *ctlh,
+                  union pptp_ctrl_union *pptpReq,
+                  unsigned int reqlen,
                   struct ip_conntrack *ct,
                   enum ip_conntrack_info ctinfo)
 {
-        struct PptpControlHeader _ctlh, *ctlh;
-        unsigned int reqlen;
-        union pptp_ctrl_union _pptpReq, *pptpReq;
         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
         u_int16_t msg;
         __be16 cid, pcid;
 
-        ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
-        if (!ctlh)
-                return NF_ACCEPT;
-        nexthdr_off += sizeof(_ctlh);
-        datalen -= sizeof(_ctlh);
-
-        reqlen = datalen;
-        if (reqlen > sizeof(*pptpReq))
-                reqlen = sizeof(*pptpReq);
-        pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
-        if (!pptpReq)
-                return NF_ACCEPT;
-
         msg = ntohs(ctlh->messageType);
         DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);
 
-        if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
-                return NF_ACCEPT;
-
         switch (msg) {
         case PPTP_START_SESSION_REQUEST:
                 /* client requests for new control session */
@@ -593,6 +535,21 @@ pptp_outbound_pkt(struct sk_buff **pskb,
         return NF_ACCEPT;
 }
 
+static const unsigned int pptp_msg_size[] = {
+        [PPTP_START_SESSION_REQUEST]  = sizeof(struct PptpStartSessionRequest),
+        [PPTP_START_SESSION_REPLY]    = sizeof(struct PptpStartSessionReply),
+        [PPTP_STOP_SESSION_REQUEST]   = sizeof(struct PptpStopSessionRequest),
+        [PPTP_STOP_SESSION_REPLY]     = sizeof(struct PptpStopSessionReply),
+        [PPTP_OUT_CALL_REQUEST]       = sizeof(struct PptpOutCallRequest),
+        [PPTP_OUT_CALL_REPLY]         = sizeof(struct PptpOutCallReply),
+        [PPTP_IN_CALL_REQUEST]        = sizeof(struct PptpInCallRequest),
+        [PPTP_IN_CALL_REPLY]          = sizeof(struct PptpInCallReply),
+        [PPTP_IN_CALL_CONNECT]        = sizeof(struct PptpInCallConnected),
+        [PPTP_CALL_CLEAR_REQUEST]     = sizeof(struct PptpClearCallRequest),
+        [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
+        [PPTP_WAN_ERROR_NOTIFY]       = sizeof(struct PptpWanErrorNotify),
+        [PPTP_SET_LINK_INFO]          = sizeof(struct PptpSetLinkInfo),
+};
 
 /* track caller id inside control connection, call expect_related */
 static int
@@ -600,16 +557,17 @@ conntrack_pptp_help(struct sk_buff **pskb,
                     struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
 
 {
-        struct pptp_pkt_hdr _pptph, *pptph;
-        struct tcphdr _tcph, *tcph;
-        u_int32_t tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
-        u_int32_t datalen;
         int dir = CTINFO2DIR(ctinfo);
         struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
-        unsigned int nexthdr_off;
-
+        struct tcphdr _tcph, *tcph;
+        struct pptp_pkt_hdr _pptph, *pptph;
+        struct PptpControlHeader _ctlh, *ctlh;
+        union pptp_ctrl_union _pptpReq, *pptpReq;
+        unsigned int tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
+        unsigned int datalen, reqlen, nexthdr_off;
         int oldsstate, oldcstate;
         int ret;
+        u_int16_t msg;
 
         /* don't do any tracking before tcp handshake complete */
         if (ctinfo != IP_CT_ESTABLISHED
@@ -648,6 +606,23 @@ conntrack_pptp_help(struct sk_buff **pskb,
                 return NF_ACCEPT;
         }
 
+        ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
+        if (!ctlh)
+                return NF_ACCEPT;
+        nexthdr_off += sizeof(_ctlh);
+        datalen -= sizeof(_ctlh);
+
+        reqlen = datalen;
+        msg = ntohs(ctlh->messageType);
+        if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
+                return NF_ACCEPT;
+        if (reqlen > sizeof(*pptpReq))
+                reqlen = sizeof(*pptpReq);
+
+        pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
+        if (!pptpReq)
+                return NF_ACCEPT;
+
         oldsstate = info->sstate;
         oldcstate = info->cstate;
 
@@ -657,11 +632,11 @@ conntrack_pptp_help(struct sk_buff **pskb,
          * established from PNS->PAC.  However, RFC makes no guarantee */
         if (dir == IP_CT_DIR_ORIGINAL)
                 /* client -> server (PNS -> PAC) */
-                ret = pptp_outbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
+                ret = pptp_outbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
                                         ctinfo);
         else
                 /* server -> client (PAC -> PNS) */
-                ret = pptp_inbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
+                ret = pptp_inbound_pkt(pskb, ctlh, pptpReq, reqlen, ct,
                                        ctinfo);
         DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
                 oldsstate, info->sstate, oldcstate, info->cstate);