RPCSEC_GSS: Share rpc_pipes when an rpc_clnt owns multiple rpcsec auth caches

Ensure that if an rpc_clnt owns more than one RPCSEC_GSS-based authentication
mechanism, then those caches will share the same 'gssd' upcall pipe.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 68 insertions, 9 deletions

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index d214aecdbeef..5ec15bb43e83 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -76,6 +76,7 @@ struct gss_pipe {
         struct rpc_pipe *pipe;
         struct rpc_clnt *clnt;
         const char *name;
+        struct kref kref;
 };
 
 struct gss_auth {
@@ -832,7 +833,6 @@ static struct gss_pipe *gss_pipe_alloc(struct rpc_clnt *clnt,
                 const char *name,
                 const struct rpc_pipe_ops *upcall_ops)
 {
-        struct net *net = rpc_net_ns(clnt);
         struct gss_pipe *p;
         int err = -ENOMEM;
 
@@ -846,19 +846,71 @@ static struct gss_pipe *gss_pipe_alloc(struct rpc_clnt *clnt,
         }
         p->name = name;
         p->clnt = clnt;
+        kref_init(&p->kref);
         rpc_init_pipe_dir_object(&p->pdo,
                         &gss_pipe_dir_object_ops,
                         p);
-        err = rpc_add_pipe_dir_object(net, &clnt->cl_pipedir_objects, &p->pdo);
-        if (!err)
-                return p;
-        rpc_destroy_pipe_data(p->pipe);
+        return p;
 err_free_gss_pipe:
         kfree(p);
 err:
         return ERR_PTR(err);
 }
 
+struct gss_alloc_pdo {
+        struct rpc_clnt *clnt;
+        const char *name;
+        const struct rpc_pipe_ops *upcall_ops;
+};
+
+static int gss_pipe_match_pdo(struct rpc_pipe_dir_object *pdo, void *data)
+{
+        struct gss_pipe *gss_pipe;
+        struct gss_alloc_pdo *args = data;
+
+        if (pdo->pdo_ops != &gss_pipe_dir_object_ops)
+                return 0;
+        gss_pipe = container_of(pdo, struct gss_pipe, pdo);
+        if (strcmp(gss_pipe->name, args->name) != 0)
+                return 0;
+        if (!kref_get_unless_zero(&gss_pipe->kref))
+                return 0;
+        return 1;
+}
+
+static struct rpc_pipe_dir_object *gss_pipe_alloc_pdo(void *data)
+{
+        struct gss_pipe *gss_pipe;
+        struct gss_alloc_pdo *args = data;
+
+        gss_pipe = gss_pipe_alloc(args->clnt, args->name, args->upcall_ops);
+        if (!IS_ERR(gss_pipe))
+                return &gss_pipe->pdo;
+        return NULL;
+}
+
+static struct gss_pipe *gss_pipe_get(struct rpc_clnt *clnt,
+                const char *name,
+                const struct rpc_pipe_ops *upcall_ops)
+{
+        struct net *net = rpc_net_ns(clnt);
+        struct rpc_pipe_dir_object *pdo;
+        struct gss_alloc_pdo args = {
+                .clnt = clnt,
+                .name = name,
+                .upcall_ops = upcall_ops,
+        };
+
+        pdo = rpc_find_or_alloc_pipe_dir_object(net,
+                        &clnt->cl_pipedir_objects,
+                        gss_pipe_match_pdo,
+                        gss_pipe_alloc_pdo,
+                        &args);
+        if (pdo != NULL)
+                return container_of(pdo, struct gss_pipe, pdo);
+        return ERR_PTR(-ENOMEM);
+}
+
 static void __gss_pipe_free(struct gss_pipe *p)
 {
         struct rpc_clnt *clnt = p->clnt;
@@ -871,10 +923,17 @@ static void __gss_pipe_free(struct gss_pipe *p)
         kfree(p);
 }
 
+static void __gss_pipe_release(struct kref *kref)
+{
+        struct gss_pipe *p = container_of(kref, struct gss_pipe, kref);
+
+        __gss_pipe_free(p);
+}
+
 static void gss_pipe_free(struct gss_pipe *p)
 {
         if (p != NULL)
-                __gss_pipe_free(p);
+                kref_put(&p->kref, __gss_pipe_release);
 }
 
 /*
@@ -930,14 +989,14 @@ gss_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
          * that we supported only the old pipe.  So we instead create
          * the new pipe first.
          */
-        gss_pipe = gss_pipe_alloc(clnt, "gssd", &gss_upcall_ops_v1);
+        gss_pipe = gss_pipe_get(clnt, "gssd", &gss_upcall_ops_v1);
         if (IS_ERR(gss_pipe)) {
                 err = PTR_ERR(gss_pipe);
                 goto err_destroy_credcache;
         }
         gss_auth->gss_pipe[1] = gss_pipe;
 
-        gss_pipe = gss_pipe_alloc(clnt, gss_auth->mech->gm_name,
+        gss_pipe = gss_pipe_get(clnt, gss_auth->mech->gm_name,
                         &gss_upcall_ops_v0);
         if (IS_ERR(gss_pipe)) {
                 err = PTR_ERR(gss_pipe);
@@ -947,7 +1006,7 @@ gss_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
 
         return auth;
 err_destroy_pipe_1:
-        __gss_pipe_free(gss_auth->gss_pipe[1]);
+        gss_pipe_free(gss_auth->gss_pipe[1]);
 err_destroy_credcache:
         rpcauth_destroy_credcache(auth);
 err_put_mech: