SUNRPC: add side channel to use non-generic cred for rpc call.
The credential passed in rpc_message.rpc_cred is always a
generic credential except in one instance.
When gss_destroying_context() calls rpc_call_null(), it passes
a specific credential that it needs to destroy.
In this case the RPC acts *on* the credential rather than
being authorized by it.
This special case deserves explicit support and providing that will
mean that rpc_message.rpc_cred is *always* generic, allowing
some optimizations.
So add "tk_op_cred" to rpc_task and "rpc_op_cred" to the setup data.
Use this to pass the cred down from rpc_call_null(), and have
rpcauth_bindcred() notice it and bind it in place.
Credit to kernel test robot <fengguang.wu@intel.com> for finding
a bug in earlier version of this patch.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index dcfcc59..27d9057 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -751,7 +751,11 @@ rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
if (flags & RPC_TASK_ASYNC)
lookupflags |= RPCAUTH_LOOKUP_NEW;
- if (cred != NULL && cred != &machine_cred)
+ if (task->tk_op_cred)
+ /* Task must use exactly this rpc_cred */
+ new = task->tk_op_cred->cr_ops->crbind(task, task->tk_op_cred,
+ lookupflags);
+ else if (cred != NULL && cred != &machine_cred)
new = cred->cr_ops->crbind(task, cred, lookupflags);
else if (cred == &machine_cred)
new = rpcauth_bind_machine_cred(task, lookupflags);