nfs/nlm: keep track of the call-state and frame for notifications

When blocking locks are used, a new frame is allocated that is used to
send the notification to the client once once the lock becomes
available. In all other cases, the frame that contains the request from
the client will be used for the reply.

Because there was no way to track the different clients with their
requests (captured in the call-state), the call-state could be free'd
before the notification was sent to the client. This caused a
use-after-free of the call-state and could trigger segfaults of the
Gluster/NFS server or incorrect replies on (un)lock requests.

By introducing a nlm4_notify_args structure, the call-state and frame
can be tracked better. This prevents the possibility of segfaulting when
the call-state is used after being free'd.

Cherry picked from commit b81997264f079983fa02bd5fa2b3715224942b00:
> BUG: 1467313
> Change-Id: I285d2bc552f509e5145653b7a50afcff827cd612
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: https://review.gluster.org/17700
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
> Reviewed-by: jiffin tony Thottan <jthottan@redhat.com>

Change-Id: I285d2bc552f509e5145653b7a50afcff827cd612
BUG: 1471870
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: https://review.gluster.org/17796
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>

2 files changed, 84 insertions, 24 deletions

diff --git a/xlators/nfs/server/src/nfs-mem-types.h b/xlators/nfs/server/src/nfs-mem-types.h
index 88c688f74f3..5cac0eb4978 100644
--- a/xlators/nfs/server/src/nfs-mem-types.h
+++ b/xlators/nfs/server/src/nfs-mem-types.h
@@ -50,6 +50,7 @@ enum gf_nfs_mem_types_ {
         gf_nfs_mt_arr,
         gf_nfs_mt_auth_cache,
         gf_nfs_mt_auth_cache_entry,
+        gf_nfs_mt_nlm4_notify,
         gf_nfs_mt_end
 };
 #endif
diff --git a/xlators/nfs/server/src/nlm4.c b/xlators/nfs/server/src/nlm4.c
index d678edc6d3a..8b7c74724a9 100644
--- a/xlators/nfs/server/src/nlm4.c
+++ b/xlators/nfs/server/src/nlm4.c
@@ -922,28 +922,64 @@ rpcerr:
         return ret;
 }
 
-int
+struct nlm4_notify_args {
+        GF_REF_DECL;            /* refcounting */
+
+        nfs3_call_state_t *cs;  /* call state, w/ lock request details */
+        call_frame_t *frame;    /* frame to us for the reply */
+};
+
+static int
 nlm4svc_send_granted_cbk (struct rpc_req *req, struct iovec *iov, int count,
                           void *myframe)
 {
-        STACK_DESTROY (((call_frame_t*)myframe)->root);
+        call_frame_t            *frame = myframe;
+        struct nlm4_notify_args *args  = frame->local;
+
+        GF_REF_PUT (args);
         return 0;
 }
 
+static void
+nlm4_notify_free (struct nlm4_notify_args *ncf)
+{
+        GF_REF_PUT (ncf->cs);
+        STACK_DESTROY (ncf->frame->root);
+        GF_FREE (ncf);
+}
+
+static struct nlm4_notify_args*
+nlm4_notify_init (nfs3_call_state_t *cs)
+{
+        struct nlm4_notify_args *ncf = NULL;
+
+        ncf = GF_CALLOC (1, sizeof (struct nlm4_notify_args),
+                         gf_nfs_mt_nlm4_notify);
+        if (!ncf)
+                /* GF_CALLOW will log the ENOMEM error */
+                goto out;
+
+        GF_REF_INIT (ncf, nlm4_notify_free);
+        ncf->cs = GF_REF_GET (cs);
+
+out:
+        return ncf;
+}
+
 static int
-nlm_handle_connect (struct rpc_clnt *rpc_clnt, nfs3_call_state_t *cs);
+nlm_handle_connect (struct rpc_clnt *rpc_clnt, struct nlm4_notify_args *ncf);
 
 int
 nlm_rpcclnt_notify (struct rpc_clnt *rpc_clnt, void *mydata,
                     rpc_clnt_event_t fn, void *data)
 {
-        nfs3_call_state_t *cs          = NULL;
+        struct nlm4_notify_args   *ncf     = mydata;
 
-        cs = mydata;
+        GF_VALIDATE_OR_GOTO ("NLM4-notify", ncf, out);
 
         switch (fn) {
         case RPC_CLNT_CONNECT:
-                nlm_handle_connect (rpc_clnt, cs);
+                nlm_handle_connect (rpc_clnt, ncf);
                 break;
 
         case RPC_CLNT_MSG:
@@ -952,18 +988,22 @@ nlm_rpcclnt_notify (struct rpc_clnt *rpc_clnt, void *mydata,
         case RPC_CLNT_DISCONNECT:
                 nlm_unset_rpc_clnt (rpc_clnt);
                 break;
+
+        case RPC_CLNT_DESTROY:
+                GF_REF_PUT (ncf);
+                break;
+
         default:
                 break;
         }
-
+out:
         return 0;
 }
 
 void *
-nlm4_establish_callback (void *csarg)
+nlm4_establish_callback (nfs3_call_state_t *cs, call_frame_t *cbk_frame)
 {
         int                           ret                        = -1;
-        nfs3_call_state_t            *cs                         = NULL;
         union gf_sock_union           sock_union;
         dict_t                       *options                    = NULL;
         char                          peerip[INET6_ADDRSTRLEN+1] = {0};
@@ -971,9 +1011,8 @@ nlm4_establish_callback (void *csarg)
         char                          myip[INET6_ADDRSTRLEN+1]   = {0};
         rpc_clnt_t                   *rpc_clnt                   = NULL;
         int                           port                       = -1;
+        struct nlm4_notify_args      *ncf                        = NULL;
 
-
-        cs = (nfs3_call_state_t *) csarg;
         glusterfs_this_set (cs->nfsx);
 
         rpc_transport_get_peeraddr (cs->trans, NULL, 0, &sock_union.storage,
@@ -1056,6 +1095,15 @@ nlm4_establish_callback (void *csarg)
                 goto err;
         }
 
+        ncf = nlm4_notify_init (cs);
+        if (!ncf) {
+                ret = -1;
+                goto err;
+        }
+
+        ncf->frame = cbk_frame;
+        ncf->frame->local = ncf;
+
         /* TODO: is 32 frames in transit enough ? */
         rpc_clnt = rpc_clnt_new (options, cs->nfsx, "NLM-client", 32);
         if (rpc_clnt == NULL) {
@@ -1064,7 +1112,7 @@ nlm4_establish_callback (void *csarg)
                 goto err;
         }
 
-        ret = rpc_clnt_register_notify (rpc_clnt, nlm_rpcclnt_notify, cs);
+        ret = rpc_clnt_register_notify (rpc_clnt, nlm_rpcclnt_notify, ncf);
         if (ret == -1) {
                 gf_msg (GF_NLM, GF_LOG_ERROR, errno, NFS_MSG_RPC_CLNT_ERROR,
                         "rpc_clnt_register_connect error");
@@ -1078,17 +1126,21 @@ nlm4_establish_callback (void *csarg)
                 ret = 0;
 
 err:
-        if (ret == -1 && rpc_clnt) {
-                rpc_clnt_unref (rpc_clnt);
+        if (ret == -1) {
+                if (rpc_clnt)
+                        rpc_clnt_unref (rpc_clnt);
+                if (ncf)
+                        GF_REF_PUT (ncf);
         }
 
         return rpc_clnt;
 }
 
-void
-nlm4svc_send_granted (nfs3_call_state_t *cs)
+static void
+nlm4svc_send_granted (struct nlm4_notify_args *ncf)
 {
         int ret = -1;
+        nfs3_call_state_t *cs = ncf->cs;
         rpc_clnt_t *rpc_clnt = NULL;
         struct iovec            outmsg = {0, };
         nlm4_testargs testargs;
@@ -1099,7 +1151,7 @@ nlm4svc_send_granted (nfs3_call_state_t *cs)
 
         rpc_clnt = nlm_get_rpc_clnt (cs->args.nlm4_lockargs.alock.caller_name);
         if (rpc_clnt == NULL) {
-                nlm4_establish_callback ((void*)cs);
+                nlm4_establish_callback (cs, ncf->frame);
                 return;
         }
 
@@ -1150,9 +1202,10 @@ nlm4svc_send_granted (nfs3_call_state_t *cs)
                 goto ret;
         }
 
+        GF_REF_GET (ncf);
         ret = rpc_clnt_submit (rpc_clnt, &nlm4clntprog, NLM4_GRANTED,
                                nlm4svc_send_granted_cbk, &outmsg, 1,
-                               NULL, 0, iobref, cs->frame, NULL, 0,
+                               NULL, 0, iobref, ncf->frame, NULL, 0,
                                NULL, 0, NULL);
 
         if (ret < 0) {
@@ -1167,7 +1220,6 @@ ret:
                 iobuf_unref (iobuf);
 
         rpc_clnt_unref (rpc_clnt);
-        nfs3_call_state_wipe (cs);
         return;
 }
 
@@ -1338,6 +1390,7 @@ nlm4svc_lock_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         char                            *caller_name = NULL;
         nfs3_call_state_t               *cs          = NULL;
         pthread_t                        thr;
+        struct nlm4_notify_args         *ncf         = NULL;
 
         cs = frame->local;
         caller_name = cs->args.nlm4_lockargs.alock.caller_name;
@@ -1359,14 +1412,18 @@ nlm4svc_lock_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 
 err:
         if (cs->args.nlm4_lockargs.block) {
-                cs->frame = copy_frame (frame);
-                frame->local = NULL;
-                nlm4svc_send_granted (cs);
+                ncf = nlm4_notify_init (cs);
+                if (ncf) {
+                        ncf->frame = copy_frame (frame);
+                        ncf->frame->local = ncf;
+                        nlm4svc_send_granted (ncf);
+                }
         } else {
                 nlm4_generic_reply (cs->req, cs->args.nlm4_lockargs.cookie,
                                     stat);
                 nfs3_call_state_wipe (cs);
         }
+
         return 0;
 }
 
@@ -2378,13 +2435,15 @@ nlm4svc_sm_notify (struct nlm_sm_status *status)
 /* RPC_CLNT_CONNECT gets called on (re)connects and should be able to handle
  * different NLM requests. */
 static int
-nlm_handle_connect (struct rpc_clnt *rpc_clnt, nfs3_call_state_t *cs)
+nlm_handle_connect (struct rpc_clnt *rpc_clnt, struct nlm4_notify_args *ncf)
 {
         int                 ret         = -1;
         int                 nlm_proc    = NLM4_NULL;
+        nfs3_call_state_t  *cs          = NULL;
         struct nlm4_lock   *alock       = NULL;
         char               *caller_name = NULL;
 
+        cs = GF_REF_GET (ncf->cs);
         if (!cs || !cs->req) {
                 gf_msg (GF_NLM, GF_LOG_ERROR, EINVAL, NFS_MSG_RPC_CLNT_ERROR,
                         "Spurious notify?!");
@@ -2426,7 +2485,7 @@ nlm_handle_connect (struct rpc_clnt *rpc_clnt, nfs3_call_state_t *cs)
                 /* extra ref taken with nlm_set_rpc_clnt() */
                 rpc_clnt_unref (rpc_clnt);
 
-                nlm4svc_send_granted (cs);
+                nlm4svc_send_granted (ncf);
                 break;
 
         case NLM4_CANCEL: