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: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfs/client.c | 13 ++-----------
fs/nfs/nfs4namespace.c | 14 +-------------
include/linux/sunrpc/clnt.h | 2 ++
net/sunrpc/clnt.c | 22 ++++++++++++++++++++++
4 files changed, 27 insertions(+), 24 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 9969444..143149d 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -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;
diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index 017b4b0..5ce7024 100644
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -192,25 +192,13 @@ out:
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(flavor);
- clone = rpc_clone_client(clnt);
- if (IS_ERR(clone))
- return clone;
-
- auth = rpcauth_create(flavor, clone);
- if (!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,
diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 523547e..34206b8 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -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 *);
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index afbeefa..cdc7564 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -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?
--
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