sctp: delay as much as possible skb_linearize

[cascardo/linux.git] / net / sctp / input.c

diff --git a/net/sctp/input.c b/net/sctp/input.c
index a701527..5cff254 100644 (file)
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -112,7 +112,6 @@ int sctp_rcv(struct sk_buff *skb)
        struct sctp_ep_common *rcvr;
        struct sctp_transport *transport = NULL;
        struct sctp_chunk *chunk;
-       struct sctphdr *sh;
        union sctp_addr src;
        union sctp_addr dest;
        int family;
@@ -124,15 +123,18 @@ int sctp_rcv(struct sk_buff *skb)
 
        __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
 
-       if (skb_linearize(skb))
+       /* If packet is too small to contain a single chunk, let's not
+        * waste time on it anymore.
+        */
+       if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
+                      skb_transport_offset(skb))
                goto discard_it;
 
-       sh = sctp_hdr(skb);
+       if (!pskb_may_pull(skb, sizeof(struct sctphdr)))
+               goto discard_it;
 
-       /* Pull up the IP and SCTP headers. */
+       /* Pull up the IP header. */
        __skb_pull(skb, skb_transport_offset(skb));
-       if (skb->len < sizeof(struct sctphdr))
-               goto discard_it;
 
        skb->csum_valid = 0; /* Previous value not applicable */
        if (skb_csum_unnecessary(skb))
@@ -141,11 +143,7 @@ int sctp_rcv(struct sk_buff *skb)
                goto discard_it;
        skb->csum_valid = 1;
 
-       skb_pull(skb, sizeof(struct sctphdr));
-
-       /* Make sure we at least have chunk headers worth of data left. */
-       if (skb->len < sizeof(struct sctp_chunkhdr))
-               goto discard_it;
+       __skb_pull(skb, sizeof(struct sctphdr));
 
        family = ipver2af(ip_hdr(skb)->version);
        af = sctp_get_af_specific(family);
@@ -230,7 +228,7 @@ int sctp_rcv(struct sk_buff *skb)
        chunk->rcvr = rcvr;
 
        /* Remember the SCTP header. */
-       chunk->sctp_hdr = sh;
+       chunk->sctp_hdr = sctp_hdr(skb);
 
        /* Set the source and destination addresses of the incoming chunk.  */
        sctp_init_addrs(chunk, &src, &dest);
@@ -660,19 +658,23 @@ out_unlock:
  */
 static int sctp_rcv_ootb(struct sk_buff *skb)
 {
-       sctp_chunkhdr_t *ch;
-       __u8 *ch_end;
-
-       ch = (sctp_chunkhdr_t *) skb->data;
+       sctp_chunkhdr_t *ch, _ch;
+       int ch_end, offset = 0;
 
        /* Scan through all the chunks in the packet.  */
        do {
+               /* Make sure we have at least the header there */
+               if (offset + sizeof(sctp_chunkhdr_t) > skb->len)
+                       break;
+
+               ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
+
                /* Break out if chunk length is less then minimal. */
                if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
                        break;
 
-               ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
-               if (ch_end > skb_tail_pointer(skb))
+               ch_end = offset + WORD_ROUND(ntohs(ch->length));
+               if (ch_end > skb->len)
                        break;
 
                /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
@@ -697,8 +699,8 @@ static int sctp_rcv_ootb(struct sk_buff *skb)
                if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
                        goto discard;
 
-               ch = (sctp_chunkhdr_t *) ch_end;
-       } while (ch_end < skb_tail_pointer(skb));
+               offset = ch_end;
+       } while (ch_end < skb->len);
 
        return 0;
 
@@ -1173,6 +1175,9 @@ static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
 {
        sctp_chunkhdr_t *ch;
 
+       if (skb_linearize(skb))
+               return NULL;
+
        ch = (sctp_chunkhdr_t *) skb->data;
 
        /* The code below will attempt to walk the chunk and extract