[PATCH 12/23] NFS/SUNRPC: don't lookup machine credential until rpcauth_bindcred().
From: NeilBrown
Date: Tue Nov 06 2018 - 23:15:03 EST
When NFS creates a machine credential, it is a "generic" credential,
not tied to any auth protocol, and is really just a container for
the princpal name.
This doesn't get linked to a genuine credential until rpcauth_bindcred()
is called.
The lookup always succeeds, so various places that test if the machine
credential is NULL, are pointless.
As a step towards getting rid of generic credentials, this patch gets
rid of generic machine credentials. The nfs_client and rpc_client
just hold a pointer to a constant principal name.
When a machine credential is wanted, a special static 'struct rpc_cred'
pointer is used. rpcauth_bindcred() recognizes this, finds the
principal from the client, and binds the correct credential.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
fs/nfs/client.c | 11 ++---------
fs/nfs/nfs4_fs.h | 9 +--------
fs/nfs/nfs4state.c | 21 ++++-----------------
fs/nfsd/nfs4callback.c | 12 ++++--------
include/linux/nfs_fs_sb.h | 3 +--
include/linux/sunrpc/auth.h | 3 ++-
include/linux/sunrpc/clnt.h | 1 +
net/sunrpc/auth.c | 42 +++++++++++++++++++++++++++++++++++++++---
net/sunrpc/auth_generic.c | 21 ---------------------
net/sunrpc/clnt.c | 1 +
10 files changed, 55 insertions(+), 69 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index cce151776709..fb1cf1a4bda2 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -151,7 +151,6 @@ EXPORT_SYMBOL_GPL(unregister_nfs_version);
struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
{
struct nfs_client *clp;
- struct rpc_cred *cred;
int err = -ENOMEM;
if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
@@ -182,9 +181,7 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
clp->cl_proto = cl_init->proto;
clp->cl_net = get_net(cl_init->net);
- cred = rpc_lookup_machine_cred("*");
- if (!IS_ERR(cred))
- clp->cl_machine_cred = cred;
+ clp->cl_principal = "*";
nfs_fscache_get_client_cookie(clp);
return clp;
@@ -246,11 +243,6 @@ void nfs_free_client(struct nfs_client *clp)
if (!IS_ERR(clp->cl_rpcclient))
rpc_shutdown_client(clp->cl_rpcclient);
- if (clp->cl_machine_cred != NULL)
- put_rpccred(clp->cl_machine_cred);
- if (clp->cl_root_cred != NULL)
- put_rpccred(clp->cl_root_cred);
-
put_net(clp->cl_net);
put_nfs_version(clp->cl_nfs_mod);
kfree(clp->cl_hostname);
@@ -529,6 +521,7 @@ int nfs_create_rpc_client(struct nfs_client *clp,
return PTR_ERR(clnt);
}
+ clnt->cl_principal = clp->cl_principal;
clp->cl_rpcclient = clnt;
return 0;
}
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 0f393eb6b4e4..431fbac63a09 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -336,7 +336,6 @@ static inline bool
_nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode,
struct rpc_clnt **clntp, struct rpc_message *msg)
{
- struct rpc_cred *newcred = NULL;
rpc_authflavor_t flavor;
if (sp4_mode == NFS_SP4_MACH_CRED_CLEANUP ||
@@ -351,13 +350,7 @@ _nfs4_state_protect(struct nfs_client *clp, unsigned long sp4_mode,
return false;
}
if (test_bit(sp4_mode, &clp->cl_sp4_flags)) {
- spin_lock(&clp->cl_lock);
- if (clp->cl_machine_cred != NULL)
- /* don't call get_rpccred on the machine cred -
- * a reference will be held for life of clp */
- newcred = clp->cl_machine_cred;
- spin_unlock(&clp->cl_lock);
- msg->rpc_cred = newcred;
+ msg->rpc_cred = rpc_machine_cred();
flavor = clp->cl_rpcclient->cl_auth->au_flavor;
WARN_ON_ONCE(flavor != RPC_AUTH_GSS_KRB5I &&
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index dde17424c4f4..f6f984d8a94b 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -166,28 +166,15 @@ int nfs40_discover_server_trunking(struct nfs_client *clp,
struct rpc_cred *nfs4_get_machine_cred(struct nfs_client *clp)
{
- struct rpc_cred *cred = clp->cl_root_cred;
-
- if (!cred)
- cred = clp->cl_machine_cred;
- if (cred)
- return get_rpccred(cred);
- return cred;
+ return get_rpccred(rpc_machine_cred());
}
static void nfs4_root_machine_cred(struct nfs_client *clp)
{
- struct rpc_cred *new;
- new = rpc_lookup_machine_cred(NULL);
- spin_lock(&clp->cl_lock);
- if (clp->cl_root_cred == NULL) {
- clp->cl_root_cred = new;
- new = NULL;
- }
- spin_unlock(&clp->cl_lock);
- if (new != NULL)
- put_rpccred(new);
+ /* Force root creds instead of machine */
+ clp->cl_principal = NULL;
+ clp->cl_rpcclient->cl_principal = NULL;
}
static struct rpc_cred *
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index c032e4c24a8d..1dcee1fd32d9 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -847,14 +847,10 @@ static int max_cb_time(struct net *net)
static struct rpc_cred *get_backchannel_cred(struct nfs4_client *clp, struct rpc_clnt *client, struct nfsd4_session *ses)
{
if (clp->cl_minorversion == 0) {
- char *principal = clp->cl_cred.cr_targ_princ ?
- clp->cl_cred.cr_targ_princ : "nfs";
- struct rpc_cred *cred;
-
- cred = rpc_lookup_machine_cred(principal);
- if (!IS_ERR(cred))
- get_rpccred(cred);
- return cred;
+ client->cl_principal = clp->cl_cred.cr_targ_princ ?
+ clp->cl_cred.cr_targ_princ : "nfs";
+
+ return get_rpccred(rpc_machine_cred());
} else {
struct rpc_auth *auth = client->cl_auth;
struct auth_cred acred = {};
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index fea51b44fe50..6aa8cc83c3b6 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -58,8 +58,7 @@ struct nfs_client {
struct nfs_subversion * cl_nfs_mod; /* pointer to nfs version module */
u32 cl_minorversion;/* NFSv4 minorversion */
- struct rpc_cred *cl_machine_cred;
- struct rpc_cred *cl_root_cred; /* Use when machine_cred is ineffective */
+ const char * cl_principal; /* used for machine cred */
#if IS_ENABLED(CONFIG_NFS_V4)
struct list_head cl_ds_clients; /* auth flavor data servers */
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 1c0468f39479..28b34c740c43 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -75,6 +75,8 @@ struct rpc_cred {
#define RPCAUTH_CRED_HASHED 2
#define RPCAUTH_CRED_NEGATIVE 3
+struct rpc_cred *rpc_machine_cred(void);
+
/* rpc_auth au_flags */
#define RPCAUTH_AUTH_NO_CRKEY_TIMEOUT 0x0001 /* underlying cred has no key timeout */
@@ -170,7 +172,6 @@ void rpc_destroy_authunix(void);
struct rpc_cred * rpc_lookup_cred(void);
struct rpc_cred * rpc_lookup_cred_nonblock(void);
struct rpc_cred * rpc_lookup_generic_cred(struct auth_cred *, int, gfp_t);
-struct rpc_cred * rpc_lookup_machine_cred(const char *service_name);
int rpcauth_register(const struct rpc_authops *);
int rpcauth_unregister(const struct rpc_authops *);
struct rpc_auth * rpcauth_create(const struct rpc_auth_create_args *,
diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 73d5c4a870fa..fc6dfbf77a9d 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -66,6 +66,7 @@ struct rpc_clnt {
struct rpc_rtt cl_rtt_default;
struct rpc_timeout cl_timeout_default;
const struct rpc_program *cl_program;
+ const char * cl_principal; /* use for machine cred */
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
struct dentry *cl_debugfs; /* debugfs directory */
#endif
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 63e2d35c10d5..9e709dcc8c39 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -39,6 +39,20 @@ static const struct rpc_authops __rcu *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
static LIST_HEAD(cred_unused);
static unsigned long number_cred_unused;
+static struct rpc_cred machine_cred = {
+ .cr_count = REFCOUNT_INIT(1),
+};
+
+/*
+ * Return the machine_cred pointer to be used whenever
+ * the a generic machine credential is needed.
+ */
+struct rpc_cred *rpc_machine_cred(void)
+{
+ return &machine_cred;
+}
+EXPORT_SYMBOL_GPL(rpc_machine_cred);
+
#define MAX_HASHTABLE_BITS (14)
static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
{
@@ -702,6 +716,22 @@ rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
return ret;
}
+static struct rpc_cred *
+rpcauth_bind_machine_cred(struct rpc_task *task, int lookupflags)
+{
+ struct rpc_auth *auth = task->tk_client->cl_auth;
+ struct auth_cred acred = {
+ .principal = task->tk_client->cl_principal,
+ .cred = init_task.cred,
+ };
+
+ if (!acred.principal)
+ return NULL;
+ dprintk("RPC: %5u looking up %s machine cred\n",
+ task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
+ return auth->au_ops->lookup_cred(auth, &acred, lookupflags);
+}
+
static struct rpc_cred *
rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
{
@@ -716,14 +746,20 @@ static int
rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
{
struct rpc_rqst *req = task->tk_rqstp;
- struct rpc_cred *new;
+ struct rpc_cred *new = NULL;
int lookupflags = 0;
if (flags & RPC_TASK_ASYNC)
lookupflags |= RPCAUTH_LOOKUP_NEW;
- if (cred != NULL)
+ if (cred != NULL && cred != &machine_cred)
new = cred->cr_ops->crbind(task, cred, lookupflags);
- else if (flags & RPC_TASK_ROOTCREDS)
+ else if (cred == &machine_cred)
+ new = rpcauth_bind_machine_cred(task, lookupflags);
+
+ /* If machine cred couldn't be bound, try a root cred */
+ if (new)
+ ;
+ else if (cred == &machine_cred || (flags & RPC_TASK_ROOTCREDS))
new = rpcauth_bind_root_cred(task, lookupflags);
else
new = rpcauth_bind_new_cred(task, lookupflags);
diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c
index 810d535c79b8..8cf5aa515c51 100644
--- a/net/sunrpc/auth_generic.c
+++ b/net/sunrpc/auth_generic.c
@@ -48,27 +48,6 @@ struct rpc_cred *rpc_lookup_cred_nonblock(void)
}
EXPORT_SYMBOL_GPL(rpc_lookup_cred_nonblock);
-/*
- * Public call interface for looking up machine creds.
- * Note that if service_name is NULL, we actually look up
- * "root" credential.
- */
-struct rpc_cred *rpc_lookup_machine_cred(const char *service_name)
-{
- struct auth_cred acred = {
- .principal = service_name,
- .cred = get_task_cred(&init_task),
- };
- struct rpc_cred *ret;
-
- dprintk("RPC: looking up machine cred for service %s\n",
- service_name);
- ret = generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
- put_cred(acred.cred);
- return ret;
-}
-EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);
-
static struct rpc_cred *generic_bind_cred(struct rpc_task *task,
struct rpc_cred *cred, int lookupflags)
{
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index ae3b8145da35..7c720b60f482 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -627,6 +627,7 @@ static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args,
new->cl_noretranstimeo = clnt->cl_noretranstimeo;
new->cl_discrtry = clnt->cl_discrtry;
new->cl_chatty = clnt->cl_chatty;
+ new->cl_principal = clnt->cl_principal;
return new;
out_err: