[SCTP]: Fix sctp_cookie alignment in the packet.

On 64 bit architectures, sctp_cookie sent as part of INIT-ACK is not
aligned on a 64 bit boundry and thus causes unaligned access exceptions.

The layout of the cookie prameter is this:
|<----- Parameter Header --------------------|<--- Cookie DATA --------
-----------------------------------------------------------------------
| param type (16 bits) | param len (16 bits) | sig [32 bytes] | cookie..
-----------------------------------------------------------------------

The cookie data portion contains 64 bit values on 64 bit architechtures
(timeval) that fall on a 32 bit alignment boundry when used as part of
the on-wire format, but align correctly when used in internal
structures.  This patch explicitely pads the on-wire format so that
it is properly aligned.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index f5c22d77feab60e030c826bcc6abe92eee1d2d26..72aeae4a006730e7a7d4bffcdabc4ddde5c48d24 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -405,8 +405,9 @@ struct sctp_cookie {
 /* The format of our cookie that we send to our peer. */
 struct sctp_signed_cookie {
        __u8 signature[SCTP_SECRET_SIZE];
+       __u32 __pad;            /* force sctp_cookie alignment to 64 bits */
        struct sctp_cookie c;
-};
+} __attribute__((packed));
 
 /* This is another convenience type to allocate memory for address
  * params for the maximum size and pass such structures around

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 556c495c6922587e3f449957ee2b536860674d86..4fe1d6c863b1c8e51a7b52ce8cdfa3a3c324db6f 100644 (file)
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1275,7 +1275,12 @@ static sctp_cookie_param_t *sctp_pack_cookie(const struct sctp_endpoint *ep,
        unsigned int keylen;
        char *key;
 
-       headersize = sizeof(sctp_paramhdr_t) + SCTP_SECRET_SIZE;
+       /* Header size is static data prior to the actual cookie, including
+        * any padding.
+        */
+       headersize = sizeof(sctp_paramhdr_t) + 
+                    (sizeof(struct sctp_signed_cookie) - 
+                     sizeof(struct sctp_cookie));
        bodysize = sizeof(struct sctp_cookie)
                + ntohs(init_chunk->chunk_hdr->length) + addrs_len;
 
@@ -1362,7 +1367,12 @@ struct sctp_association *sctp_unpack_cookie(
        struct sk_buff *skb = chunk->skb;
        struct timeval tv;
 
-       headersize = sizeof(sctp_chunkhdr_t) + SCTP_SECRET_SIZE;
+       /* Header size is static data prior to the actual cookie, including
+        * any padding.
+        */
+       headersize = sizeof(sctp_chunkhdr_t) +
+                    (sizeof(struct sctp_signed_cookie) - 
+                     sizeof(struct sctp_cookie));
        bodysize = ntohs(chunk->chunk_hdr->length) - headersize;
        fixed_size = headersize + sizeof(struct sctp_cookie);