[PATCH] gss: remove legacy gssd upcall pipe

[bfields@fieldses.org (J. Bruce Fields)]

From: "J. Bruce Fields" <bfields@redhat.com>

This code exists only for compatibility with nfs-utils before
0cfdc66de043 "gssd: handle new client upcall" (which first appeared in
nfs-utils version 1.2.2, in 2019).  After 12 years, maybe it's time to
drop that compatibility code.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 net/sunrpc/auth_gss/auth_gss.c | 102 ++++-----------------------------
 1 file changed, 12 insertions(+), 90 deletions(-)

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 5f42aa5fc612..8929178410e7 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -73,13 +73,7 @@ struct gss_auth {
 	enum rpc_gss_svc service;
 	struct rpc_clnt *client;
 	struct net *net;
-	/*
-	 * There are two upcall pipes; dentry[1], named "gssd", is used
-	 * for the new text-based upcall; dentry[0] is named after the
-	 * mechanism (for example, "krb5") and exists for
-	 * backwards-compatibility with older gssd's.
-	 */
-	struct gss_pipe *gss_pipe[2];
+	struct gss_pipe *gss_pipe;
 	const char *target_name;
 };
 
@@ -90,7 +84,6 @@ static DECLARE_WAIT_QUEUE_HEAD(pipe_version_waitqueue);
 static void gss_put_auth(struct gss_auth *gss_auth);
 
 static void gss_free_ctx(struct gss_cl_ctx *);
-static const struct rpc_pipe_ops gss_upcall_ops_v0;
 static const struct rpc_pipe_ops gss_upcall_ops_v1;
 
 static inline struct gss_cl_ctx *
@@ -261,7 +254,7 @@ static int get_pipe_version(struct net *net)
 	spin_lock(&pipe_version_lock);
 	if (sn->pipe_version >= 0) {
 		atomic_inc(&sn->pipe_users);
-		ret = sn->pipe_version;
+		ret = 0;
 	} else
 		ret = -EAGAIN;
 	spin_unlock(&pipe_version_lock);
@@ -385,31 +378,6 @@ gss_upcall_callback(struct rpc_task *task)
 	gss_release_msg(gss_msg);
 }
 
-static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg,
-			      const struct cred *cred)
-{
-	struct user_namespace *userns = cred->user_ns;
-
-	uid_t uid = from_kuid_munged(userns, gss_msg->uid);
-	memcpy(gss_msg->databuf, &uid, sizeof(uid));
-	gss_msg->msg.data = gss_msg->databuf;
-	gss_msg->msg.len = sizeof(uid);
-
-	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,
@@ -507,17 +475,15 @@ gss_alloc_msg(struct gss_auth *gss_auth,
 		kuid_t uid, const char *service_name)
 {
 	struct gss_upcall_msg *gss_msg;
-	int vers;
 	int err = -ENOMEM;
 
 	gss_msg = kzalloc(sizeof(*gss_msg), GFP_NOFS);
 	if (gss_msg == NULL)
 		goto err;
-	vers = get_pipe_version(gss_auth->net);
-	err = vers;
+	err = get_pipe_version(gss_auth->net);
 	if (err < 0)
 		goto err_free_msg;
-	gss_msg->pipe = gss_auth->gss_pipe[vers]->pipe;
+	gss_msg->pipe = gss_auth->gss_pipe->pipe;
 	INIT_LIST_HEAD(&gss_msg->list);
 	rpc_init_wait_queue(&gss_msg->rpc_waitqueue, "RPCSEC_GSS upcall waitq");
 	init_waitqueue_head(&gss_msg->waitqueue);
@@ -777,38 +743,21 @@ gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
 	return err;
 }
 
-static int gss_pipe_open(struct inode *inode, int new_version)
+static int gss_pipe_open(struct inode *inode)
 {
 	struct net *net = inode->i_sb->s_fs_info;
 	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
-	int ret = 0;
 
 	spin_lock(&pipe_version_lock);
 	if (sn->pipe_version < 0) {
-		/* First open of any gss pipe determines the version: */
-		sn->pipe_version = new_version;
+		sn->pipe_version = 1;
 		rpc_wake_up(&pipe_version_rpc_waitqueue);
 		wake_up(&pipe_version_waitqueue);
-	} else if (sn->pipe_version != new_version) {
-		/* Trying to open a pipe of a different version */
-		ret = -EBUSY;
-		goto out;
 	}
 	atomic_inc(&sn->pipe_users);
-out:
 	spin_unlock(&pipe_version_lock);
-	return ret;
-
-}
-
-static int gss_pipe_open_v0(struct inode *inode)
-{
-	return gss_pipe_open(inode, 0);
-}
+	return 0;
 
-static int gss_pipe_open_v1(struct inode *inode)
-{
-	return gss_pipe_open(inode, 1);
 }
 
 static void
@@ -1039,30 +988,14 @@ gss_create_new(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
 	err = rpcauth_init_credcache(auth);
 	if (err)
 		goto err_put_mech;
-	/*
-	 * Note: if we created the old pipe first, then someone who
-	 * examined the directory at the right moment might conclude
-	 * that we supported only the old pipe.  So we instead create
-	 * the new pipe first.
-	 */
 	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_get(clnt, gss_auth->mech->gm_name,
-			&gss_upcall_ops_v0);
-	if (IS_ERR(gss_pipe)) {
-		err = PTR_ERR(gss_pipe);
-		goto err_destroy_pipe_1;
-	}
-	gss_auth->gss_pipe[0] = gss_pipe;
+	gss_auth->gss_pipe = gss_pipe;
 
 	return gss_auth;
-err_destroy_pipe_1:
-	gss_pipe_free(gss_auth->gss_pipe[1]);
 err_destroy_credcache:
 	rpcauth_destroy_credcache(auth);
 err_put_mech:
@@ -1081,8 +1014,7 @@ gss_create_new(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
 static void
 gss_free(struct gss_auth *gss_auth)
 {
-	gss_pipe_free(gss_auth->gss_pipe[0]);
-	gss_pipe_free(gss_auth->gss_pipe[1]);
+	gss_pipe_free(gss_auth->gss_pipe);
 	gss_mech_put(gss_auth->mech);
 	put_net(gss_auth->net);
 	kfree(gss_auth->target_name);
@@ -1117,10 +1049,8 @@ gss_destroy(struct rpc_auth *auth)
 		spin_unlock(&gss_auth_hash_lock);
 	}
 
-	gss_pipe_free(gss_auth->gss_pipe[0]);
-	gss_auth->gss_pipe[0] = NULL;
-	gss_pipe_free(gss_auth->gss_pipe[1]);
-	gss_auth->gss_pipe[1] = NULL;
+	gss_pipe_free(gss_auth->gss_pipe);
+	gss_auth->gss_pipe = NULL;
 	rpcauth_destroy_credcache(auth);
 
 	gss_put_auth(gss_auth);
@@ -2179,19 +2109,11 @@ static const struct rpc_credops gss_nullops = {
 	.crstringify_acceptor	= gss_stringify_acceptor,
 };
 
-static const struct rpc_pipe_ops gss_upcall_ops_v0 = {
-	.upcall		= gss_v0_upcall,
-	.downcall	= gss_pipe_downcall,
-	.destroy_msg	= gss_pipe_destroy_msg,
-	.open_pipe	= gss_pipe_open_v0,
-	.release_pipe	= gss_pipe_release,
-};
-
 static const struct rpc_pipe_ops gss_upcall_ops_v1 = {
 	.upcall		= gss_v1_upcall,
 	.downcall	= gss_pipe_downcall,
 	.destroy_msg	= gss_pipe_destroy_msg,
-	.open_pipe	= gss_pipe_open_v1,
+	.open_pipe	= gss_pipe_open,
 	.release_pipe	= gss_pipe_release,
 };
 
-- 
2.31.1