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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>
This commit is contained in:
NeilBrown 2018-12-03 11:30:30 +11:00 committed by Anna Schumaker
parent a68a72e135
commit 1de7eea929
4 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/sunrpc/sched.h
View File

@ -71,6 +71,7 @@ struct rpc_task {
struct rpc_clnt * tk_client; /* RPC client */
struct rpc_xprt * tk_xprt; /* Transport */
struct rpc_cred * tk_op_cred; /* cred being operated on */
struct rpc_rqst * tk_rqstp; /* RPC request */
@ -105,6 +106,7 @@ struct rpc_task_setup {
struct rpc_task *task;
struct rpc_clnt *rpc_client;
struct rpc_xprt *rpc_xprt;
struct rpc_cred *rpc_op_cred; /* credential being operated on */
const struct rpc_message *rpc_message;
const struct rpc_call_ops *callback_ops;
void *callback_data;

6
net/sunrpc/auth.c
View File

@ -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);

2
net/sunrpc/clnt.c
View File

@ -2534,12 +2534,12 @@ struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt,
{
struct rpc_message msg = {
.rpc_proc = &rpcproc_null,
.rpc_cred = cred,
};
struct rpc_task_setup task_setup_data = {
.rpc_client = clnt,
.rpc_xprt = xprt,
.rpc_message = &msg,
.rpc_op_cred = cred,
.callback_ops = (ops != NULL) ? ops : &rpc_default_ops,
.callback_data = data,
.flags = flags,

3
net/sunrpc/sched.c
View File

@ -997,6 +997,8 @@ static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *ta
task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
if (task->tk_ops->rpc_call_prepare != NULL)
task->tk_action = rpc_prepare_task;
@ -1054,6 +1056,7 @@ static void rpc_free_task(struct rpc_task *task)
{
unsigned short tk_flags = task->tk_flags;
put_rpccred(task->tk_op_cred);
rpc_release_calldata(task->tk_ops, task->tk_calldata);
if (tk_flags & RPC_TASK_DYNAMIC) {