[SCTP]: Set assoc_id correctly during INIT collision.

During the INIT/COOKIE-ACK collision cases, it's possible to get
into a situation where the association id is not yet set at the time
of the user event generation.  As a result, user events have an
association id set to 0 which will confuse applications.

This happens if we hit case B of duplicate cookie processing.
In the particular example found and provided by Oscar Isaula
<Oscar.Isaula@motorola.com>, flow looks like this:
A				B
---- INIT------->  (lost)
	    <---------INIT------
---- INIT-ACK--->
	    <------ Cookie ECHO

When the Cookie Echo is received, we end up trying to update the
association that was created on A as a result of the (lost) INIT,
but that association doesn't have the ID set yet.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 77 insertions, 31 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index db73ef97485a..df94e3cdfba3 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1103,6 +1103,13 @@ void sctp_assoc_update(struct sctp_association *asoc,
                         asoc->ssnmap = new->ssnmap;
                         new->ssnmap = NULL;
                 }
+
+                if (!asoc->assoc_id) {
+                        /* get a new association id since we don't have one
+                         * yet.
+                         */
+                        sctp_assoc_set_id(asoc, GFP_ATOMIC);
+                }
         }
 }
 
@@ -1375,3 +1382,25 @@ out:
         sctp_read_unlock(&asoc->base.addr_lock);
         return found;
 }
+
+/* Set an association id for a given association */
+int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
+{
+        int assoc_id;
+        int error = 0;
+retry:
+        if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
+                return -ENOMEM;
+
+        spin_lock_bh(&sctp_assocs_id_lock);
+        error = idr_get_new_above(&sctp_assocs_id, (void *)asoc,
+                                    1, &assoc_id);
+        spin_unlock_bh(&sctp_assocs_id_lock);
+        if (error == -EAGAIN)
+                goto retry;
+        else if (error)
+                return error;
+
+        asoc->assoc_id = (sctp_assoc_t) assoc_id;
+        return error;
+}
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index be783a3761c4..8d18f570c2e6 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1939,7 +1939,6 @@ int sctp_process_init(struct sctp_association *asoc, sctp_cid_t cid,
          * association.
          */
         if (!asoc->temp) {
-                int assoc_id;
                 int error;
 
                 asoc->ssnmap = sctp_ssnmap_new(asoc->c.sinit_max_instreams,
@@ -1947,19 +1946,9 @@ int sctp_process_init(struct sctp_association *asoc, sctp_cid_t cid,
                 if (!asoc->ssnmap)
                         goto clean_up;
 
-        retry:
-                if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
+                error = sctp_assoc_set_id(asoc, gfp);
+                if (error)
                         goto clean_up;
-                spin_lock_bh(&sctp_assocs_id_lock);
-                error = idr_get_new_above(&sctp_assocs_id, (void *)asoc, 1,
-                                          &assoc_id);
-                spin_unlock_bh(&sctp_assocs_id_lock);
-                if (error == -EAGAIN)
-                        goto retry;
-                else if (error)
-                        goto clean_up;
-
-                asoc->assoc_id = (sctp_assoc_t) assoc_id;
         }
 
         /* ADDIP Section 4.1 ASCONF Chunk Procedures
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index b37a7adeb150..d9fad4f6ffc3 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -862,6 +862,33 @@ static void sctp_cmd_set_sk_err(struct sctp_association *asoc, int error)
                 sk->sk_err = error;
 }
 
+/* Helper function to generate an association change event */
+static void sctp_cmd_assoc_change(sctp_cmd_seq_t *commands,
+                                 struct sctp_association *asoc,
+                                 u8 state)
+{
+        struct sctp_ulpevent *ev;
+
+        ev = sctp_ulpevent_make_assoc_change(asoc, 0, state, 0,
+                                            asoc->c.sinit_num_ostreams,
+                                            asoc->c.sinit_max_instreams,
+                                            NULL, GFP_ATOMIC);
+        if (ev)
+                sctp_ulpq_tail_event(&asoc->ulpq, ev);
+}
+
+/* Helper function to generate an adaptation indication event */
+static void sctp_cmd_adaptation_ind(sctp_cmd_seq_t *commands,
+                                    struct sctp_association *asoc)
+{
+        struct sctp_ulpevent *ev;
+
+        ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
+
+        if (ev)
+                sctp_ulpq_tail_event(&asoc->ulpq, ev);
+}
+
 /* These three macros allow us to pull the debugging code out of the
  * main flow of sctp_do_sm() to keep attention focused on the real
  * functionality there.
@@ -1485,6 +1512,14 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
                 case SCTP_CMD_SET_SK_ERR:
                         sctp_cmd_set_sk_err(asoc, cmd->obj.error);
                         break;
+                case SCTP_CMD_ASSOC_CHANGE:
+                        sctp_cmd_assoc_change(commands, asoc,
+                                              cmd->obj.u8);
+                        break;
+                case SCTP_CMD_ADAPTATION_IND:
+                        sctp_cmd_adaptation_ind(commands, asoc);
+                        break;
+
                 default:
                         printk(KERN_WARNING "Impossible command: %u, %p\n",
                                cmd->verb, cmd->obj.ptr);
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 9e28a5d51200..f02ce3dddb7b 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -1656,7 +1656,6 @@ static sctp_disposition_t sctp_sf_do_dupcook_b(const struct sctp_endpoint *ep,
                                         struct sctp_association *new_asoc)
 {
         sctp_init_chunk_t *peer_init;
-        struct sctp_ulpevent *ev;
         struct sctp_chunk *repl;
 
         /* new_asoc is a brand-new association, so these are not yet
@@ -1687,34 +1686,28 @@ static sctp_disposition_t sctp_sf_do_dupcook_b(const struct sctp_endpoint *ep,
          * D) IMPLEMENTATION NOTE: An implementation may choose to
          * send the Communication Up notification to the SCTP user
          * upon reception of a valid COOKIE ECHO chunk.
+         *
+         * Sadly, this needs to be implemented as a side-effect, because
+         * we are not guaranteed to have set the association id of the real
+         * association and so these notifications need to be delayed until
+         * the association id is allocated.
          */
-        ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP, 0,
-                                             new_asoc->c.sinit_num_ostreams,
-                                             new_asoc->c.sinit_max_instreams,
-                                             NULL, GFP_ATOMIC);
-        if (!ev)
-                goto nomem_ev;
 
-        sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
+        sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_CHANGE, SCTP_U8(SCTP_COMM_UP));
 
         /* Sockets API Draft Section 5.3.1.6
          * When a peer sends a Adaptation Layer Indication parameter , SCTP
          * delivers this notification to inform the application that of the
          * peers requested adaptation layer.
+         *
+         * This also needs to be done as a side effect for the same reason as
+         * above.
          */
-        if (asoc->peer.adaptation_ind) {
-                ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
-                if (!ev)
-                        goto nomem_ev;
-
-                sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
-                                SCTP_ULPEVENT(ev));
-        }
+        if (asoc->peer.adaptation_ind)
+                sctp_add_cmd_sf(commands, SCTP_CMD_ADAPTATION_IND, SCTP_NULL());
 
         return SCTP_DISPOSITION_CONSUME;
 
-nomem_ev:
-        sctp_chunk_free(repl);
 nomem:
         return SCTP_DISPOSITION_NOMEM;
 }