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Commit ba9b584c authored by Chuck Lever's avatar Chuck Lever Committed by Trond Myklebust
Browse files

SUNRPC: Introduce rpc_clone_client_set_auth() 



An ULP is supposed to be able to replace a GSS rpc_auth object with
another GSS rpc_auth object using rpcauth_create().  However,
rpcauth_create() in 3.5 reliably fails with -EEXIST in this case.
This is because when gss_create() attempts to create the upcall pipes,
sometimes they are already there.  For example if a pipe FS mount
event occurs, or a previous GSS flavor was in use for this rpc_clnt.

It turns out that's not the only problem here.  While working on a
fix for the above problem, we noticed that replacing an rpc_clnt's
rpc_auth is not safe, since dereferencing the cl_auth field is not
protected in any way.

So we're deprecating the ability of rpcauth_create() to switch an
rpc_clnt's security flavor during normal operation.  Instead, let's
add a fresh API that clones an rpc_clnt and gives the clone a new
flavor before it's used.

This makes immediate use of the new __rpc_clone_client() helper.

This can be used in a similar fashion to rpcauth_create() when a
client is hunting for the correct security flavor.  Instead of
replacing an rpc_clnt's security flavor in a loop, the ULP replaces
the whole rpc_clnt.

To fix the -EEXIST problem, any ULP logic that relies on replacing
an rpc_clnt's rpc_auth with rpcauth_create() must be changed to use
this API instead.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 1b63a751

fs/nfs/client.c

+2 −11
Original line number Diff line number Diff line
@@ -668,7 +668,8 @@ int nfs_init_server_rpcclient(struct nfs_server *server, 
{

	struct nfs_client *clp = server->nfs_client;



	server->client = rpc_clone_client(clp->cl_rpcclient);

	server->client = rpc_clone_client_set_auth(clp->cl_rpcclient,

							pseudoflavour);

	if (IS_ERR(server->client)) {

		dprintk("%s: couldn't create rpc_client!\n", __func__);

		return PTR_ERR(server->client);
@@ -678,16 +679,6 @@ int nfs_init_server_rpcclient(struct nfs_server *server, 
			timeo,

			sizeof(server->client->cl_timeout_default));

	server->client->cl_timeout = &server->client->cl_timeout_default;



	if (pseudoflavour != clp->cl_rpcclient->cl_auth->au_flavor) {

		struct rpc_auth *auth;



		auth = rpcauth_create(pseudoflavour, server->client);

		if (IS_ERR(auth)) {

			dprintk("%s: couldn't create credcache!\n", __func__);

			return PTR_ERR(auth);

		}

	}

	server->client->cl_softrtry = 0;

	if (server->flags & NFS_MOUNT_SOFT)

		server->client->cl_softrtry = 1;

fs/nfs/nfs4namespace.c

+1 −13
Original line number Diff line number Diff line
@@ -192,25 +192,13 @@ static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr 
struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,

					struct qstr *name)

{

	struct rpc_clnt *clone;

	struct rpc_auth *auth;

	rpc_authflavor_t flavor;



	flavor = nfs4_negotiate_security(inode, name);

	if ((int)flavor < 0)

		return ERR_PTR((int)flavor);



	clone = rpc_clone_client(clnt);

	if (IS_ERR(clone))

		return clone;



	auth = rpcauth_create(flavor, clone);

	if (IS_ERR(auth)) {

		rpc_shutdown_client(clone);

		clone = ERR_PTR(-EIO);

	}



	return clone;

	return rpc_clone_client_set_auth(clnt, flavor);

}



static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,

include/linux/sunrpc/clnt.h

+2 −0
Original line number Diff line number Diff line
@@ -130,6 +130,8 @@ struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *, 
				const struct rpc_program *, u32);

void rpc_task_reset_client(struct rpc_task *task, struct rpc_clnt *clnt);

struct rpc_clnt *rpc_clone_client(struct rpc_clnt *);

struct rpc_clnt *rpc_clone_client_set_auth(struct rpc_clnt *,

				rpc_authflavor_t);

void		rpc_shutdown_client(struct rpc_clnt *);

void		rpc_release_client(struct rpc_clnt *);

void		rpc_task_release_client(struct rpc_task *);

net/sunrpc/clnt.c

+22 −0
Original line number Diff line number Diff line
@@ -548,6 +548,28 @@ struct rpc_clnt *rpc_clone_client(struct rpc_clnt *clnt) 
}

EXPORT_SYMBOL_GPL(rpc_clone_client);



/**

 * rpc_clone_client_set_auth - Clone an RPC client structure and set its auth

 *

 * @clnt: RPC client whose parameters are copied

 * @auth: security flavor for new client

 *

 * Returns a fresh RPC client or an ERR_PTR.

 */

struct rpc_clnt *

rpc_clone_client_set_auth(struct rpc_clnt *clnt, rpc_authflavor_t flavor)

{

	struct rpc_create_args args = {

		.program	= clnt->cl_program,

		.prognumber	= clnt->cl_prog,

		.version	= clnt->cl_vers,

		.authflavor	= flavor,

		.client_name	= clnt->cl_principal,

	};

	return __rpc_clone_client(&args, clnt);

}

EXPORT_SYMBOL_GPL(rpc_clone_client_set_auth);



/*

 * Kill all tasks for the given client.

 * XXX: kill their descendants as well?