SUNRPC: Use namespace of listening daemon in the client AUTH_GSS upcall

When the client needs to talk to rpc.gssd, we should ensure that the
uid argument is encoded to match the user namespace of the daemon.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 5dc2aef2232a3e27f5323d64731a5c1b97ecb89d..b2cbc83d39c775cea6b246bf62d9773536d1f090 100644 (file)
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -269,6 +269,7 @@ err:
 struct gss_upcall_msg {
        refcount_t count;
        kuid_t  uid;
+       const char *service_name;
        struct rpc_pipe_msg msg;
        struct list_head list;
        struct gss_auth *auth;
@@ -316,6 +317,7 @@ gss_release_msg(struct gss_upcall_msg *gss_msg)
                gss_put_ctx(gss_msg->ctx);
        rpc_destroy_wait_queue(&gss_msg->rpc_waitqueue);
        gss_put_auth(gss_msg->auth);
+       kfree_const(gss_msg->service_name);
        kfree(gss_msg);
 }
 
@@ -410,10 +412,10 @@ gss_upcall_callback(struct rpc_task *task)
        gss_release_msg(gss_msg);
 }
 
-static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg)
+static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg,
+                             const struct cred *cred)
 {
-       struct user_namespace *userns = gss_msg->auth->client->cl_cred ?
-               gss_msg->auth->client->cl_cred->user_ns : &init_user_ns;
+       struct user_namespace *userns = cred->user_ns;
 
        uid_t uid = from_kuid_munged(userns, gss_msg->uid);
        memcpy(gss_msg->databuf, &uid, sizeof(uid));
@@ -423,12 +425,24 @@ static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg)
        BUILD_BUG_ON(sizeof(uid) > sizeof(gss_msg->databuf));
 }
 
+static ssize_t
+gss_v0_upcall(struct file *file, struct rpc_pipe_msg *msg,
+               char __user *buf, size_t buflen)
+{
+       struct gss_upcall_msg *gss_msg = container_of(msg,
+                                                     struct gss_upcall_msg,
+                                                     msg);
+       if (msg->copied == 0)
+               gss_encode_v0_msg(gss_msg, file->f_cred);
+       return rpc_pipe_generic_upcall(file, msg, buf, buflen);
+}
+
 static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
                                const char *service_name,
-                               const char *target_name)
+                               const char *target_name,
+                               const struct cred *cred)
 {
-       struct user_namespace *userns = gss_msg->auth->client->cl_cred ?
-               gss_msg->auth->client->cl_cred->user_ns : &init_user_ns;
+       struct user_namespace *userns = cred->user_ns;
        struct gss_api_mech *mech = gss_msg->auth->mech;
        char *p = gss_msg->databuf;
        size_t buflen = sizeof(gss_msg->databuf);
@@ -496,6 +510,25 @@ out_overflow:
        return -ENOMEM;
 }
 
+static ssize_t
+gss_v1_upcall(struct file *file, struct rpc_pipe_msg *msg,
+               char __user *buf, size_t buflen)
+{
+       struct gss_upcall_msg *gss_msg = container_of(msg,
+                                                     struct gss_upcall_msg,
+                                                     msg);
+       int err;
+       if (msg->copied == 0) {
+               err = gss_encode_v1_msg(gss_msg,
+                                       gss_msg->service_name,
+                                       gss_msg->auth->target_name,
+                                       file->f_cred);
+               if (err)
+                       return err;
+       }
+       return rpc_pipe_generic_upcall(file, msg, buf, buflen);
+}
+
 static struct gss_upcall_msg *
 gss_alloc_msg(struct gss_auth *gss_auth,
                kuid_t uid, const char *service_name)
@@ -518,16 +551,11 @@ gss_alloc_msg(struct gss_auth *gss_auth,
        refcount_set(&gss_msg->count, 1);
        gss_msg->uid = uid;
        gss_msg->auth = gss_auth;
-       switch (vers) {
-       case 0:
-               gss_encode_v0_msg(gss_msg);
-               break;
-       default:
-               err = gss_encode_v1_msg(gss_msg, service_name, gss_auth->target_name);
-               if (err)
+       if (service_name) {
+               gss_msg->service_name = kstrdup_const(service_name, GFP_NOFS);
+               if (!gss_msg->service_name)
                        goto err_put_pipe_version;
        }
-       kref_get(&gss_auth->kref);
        return gss_msg;
 err_put_pipe_version:
        put_pipe_version(gss_auth->net);
@@ -2120,7 +2148,7 @@ static const struct rpc_credops gss_nullops = {
 };
 
 static const struct rpc_pipe_ops gss_upcall_ops_v0 = {
-       .upcall         = rpc_pipe_generic_upcall,
+       .upcall         = gss_v0_upcall,
        .downcall       = gss_pipe_downcall,
        .destroy_msg    = gss_pipe_destroy_msg,
        .open_pipe      = gss_pipe_open_v0,
@@ -2128,7 +2156,7 @@ static const struct rpc_pipe_ops gss_upcall_ops_v0 = {
 };
 
 static const struct rpc_pipe_ops gss_upcall_ops_v1 = {
-       .upcall         = rpc_pipe_generic_upcall,
+       .upcall         = gss_v1_upcall,
        .downcall       = gss_pipe_downcall,
        .destroy_msg    = gss_pipe_destroy_msg,
        .open_pipe      = gss_pipe_open_v1,