SUNRPC: Use struct xdr_stream when decoding RPC Reply header

Modernize and harden the code path that parses an RPC Reply
message.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 45 insertions, 43 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index e9735089bd66..803e93105af1 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -79,7 +79,8 @@ static void	call_connect_status(struct rpc_task *task);
 
 static int      rpc_encode_header(struct rpc_task *task,
                                   struct xdr_stream *xdr);
-static __be32   *rpc_decode_header(struct rpc_task *task);
+static int      rpc_decode_header(struct rpc_task *task,
+                                  struct xdr_stream *xdr);
 static int      rpc_ping(struct rpc_clnt *clnt);
 
 static void rpc_register_client(struct rpc_clnt *clnt)
@@ -2251,12 +2252,11 @@ call_decode(struct rpc_task *task)
 {
         struct rpc_clnt *clnt = task->tk_client;
         struct rpc_rqst *req = task->tk_rqstp;
-        kxdrdproc_t     decode = task->tk_msg.rpc_proc->p_decode;
-        __be32          *p;
+        struct xdr_stream xdr;
 
         dprint_status(task);
 
-        if (!decode) {
+        if (!task->tk_msg.rpc_proc->p_decode) {
                 task->tk_action = rpc_exit_task;
                 return;
         }
@@ -2292,29 +2292,27 @@ call_decode(struct rpc_task *task)
                 goto out_retry;
         }
 
-        p = rpc_decode_header(task);
-        if (IS_ERR(p)) {
-                if (p == ERR_PTR(-EAGAIN))
-                        goto out_retry;
+        xdr_init_decode(&xdr, &req->rq_rcv_buf,
+                        req->rq_rcv_buf.head[0].iov_base, req);
+        switch (rpc_decode_header(task, &xdr)) {
+        case 0:
+                task->tk_action = rpc_exit_task;
+                task->tk_status = rpcauth_unwrap_resp(task, &xdr);
+                dprintk("RPC: %5u %s result %d\n",
+                        task->tk_pid, __func__, task->tk_status);
                 return;
-        }
-        task->tk_action = rpc_exit_task;
-
-        task->tk_status = rpcauth_unwrap_resp(task, decode, req, p,
-                                              task->tk_msg.rpc_resp);
-
-        dprintk("RPC: %5u call_decode result %d\n", task->tk_pid,
-                        task->tk_status);
-        return;
+        case -EAGAIN:
 out_retry:
-        task->tk_status = 0;
-        /* Note: rpc_decode_header() may have freed the RPC slot */
-        if (task->tk_rqstp == req) {
-                xdr_free_bvec(&req->rq_rcv_buf);
-                req->rq_reply_bytes_recvd = req->rq_rcv_buf.len = 0;
-                if (task->tk_client->cl_discrtry)
-                        xprt_conditional_disconnect(req->rq_xprt,
-                                        req->rq_connect_cookie);
+                task->tk_status = 0;
+                /* Note: rpc_decode_header() may have freed the RPC slot */
+                if (task->tk_rqstp == req) {
+                        xdr_free_bvec(&req->rq_rcv_buf);
+                        req->rq_reply_bytes_recvd = 0;
+                        req->rq_rcv_buf.len = 0;
+                        if (task->tk_client->cl_discrtry)
+                                xprt_conditional_disconnect(req->rq_xprt,
+                                                            req->rq_connect_cookie);
+                }
         }
 }
 
@@ -2347,14 +2345,12 @@ out_fail:
         return error;
 }
 
-static noinline __be32 *
-rpc_decode_header(struct rpc_task *task)
+static noinline int
+rpc_decode_header(struct rpc_task *task, struct xdr_stream *xdr)
 {
         struct rpc_clnt *clnt = task->tk_client;
-        struct kvec *iov = &task->tk_rqstp->rq_rcv_buf.head[0];
-        int len = task->tk_rqstp->rq_rcv_buf.len >> 2;
-        __be32  *p = iov->iov_base;
         int error = -EACCES;
+        __be32 *p;
 
         /* RFC-1014 says that the representation of XDR data must be a
          * multiple of four bytes
@@ -2363,25 +2359,26 @@ rpc_decode_header(struct rpc_task *task)
          */
         if (task->tk_rqstp->rq_rcv_buf.len & 3)
                 goto out_badlen;
-        if ((len -= 3) < 0)
-                goto out_unparsable;
 
+        p = xdr_inline_decode(xdr, 3 * sizeof(*p));
+        if (!p)
+                goto out_unparsable;
         p++;    /* skip XID */
         if (*p++ != rpc_reply)
                 goto out_unparsable;
         if (*p++ != rpc_msg_accepted)
                 goto out_msg_denied;
 
-        p = rpcauth_checkverf(task, p);
-        if (IS_ERR(p))
+        error = rpcauth_checkverf(task, xdr);
+        if (error)
                 goto out_verifier;
 
-        len = p - (__be32 *)iov->iov_base - 1;
-        if (len < 0)
+        p = xdr_inline_decode(xdr, sizeof(*p));
+        if (!p)
                 goto out_unparsable;
-        switch (*p++) {
+        switch (*p) {
         case rpc_success:
-                return p;
+                return 0;
         case rpc_prog_unavail:
                 trace_rpc__prog_unavail(task);
                 error = -EPFNOSUPPORT;
@@ -2406,11 +2403,11 @@ out_garbage:
         if (task->tk_garb_retry) {
                 task->tk_garb_retry--;
                 task->tk_action = call_encode;
-                return ERR_PTR(-EAGAIN);
+                return -EAGAIN;
         }
 out_err:
         rpc_exit(task, error);
-        return ERR_PTR(error);
+        return error;
 
 out_badlen:
         trace_rpc__unparsable(task);
@@ -2424,10 +2421,12 @@ out_unparsable:
 
 out_verifier:
         trace_rpc_bad_verifier(task);
-        error = PTR_ERR(p);
         goto out_garbage;
 
 out_msg_denied:
+        p = xdr_inline_decode(xdr, sizeof(*p));
+        if (!p)
+                goto out_unparsable;
         switch (*p++) {
         case rpc_auth_error:
                 break;
@@ -2441,6 +2440,9 @@ out_msg_denied:
                 goto out_err;
         }
 
+        p = xdr_inline_decode(xdr, sizeof(*p));
+        if (!p)
+                goto out_unparsable;
         switch (*p++) {
         case rpc_autherr_rejectedcred:
         case rpc_autherr_rejectedverf:
@@ -2454,7 +2456,7 @@ out_msg_denied:
                 /* Ensure we obtain a new XID! */
                 xprt_release(task);
                 task->tk_action = call_reserve;
-                return ERR_PTR(-EAGAIN);
+                return -EAGAIN;
         case rpc_autherr_badcred:
         case rpc_autherr_badverf:
                 /* possibly garbled cred/verf? */
@@ -2463,7 +2465,7 @@ out_msg_denied:
                 task->tk_garb_retry--;
                 trace_rpc__bad_creds(task);
                 task->tk_action = call_encode;
-                return ERR_PTR(-EAGAIN);
+                return -EAGAIN;
         case rpc_autherr_tooweak:
                 trace_rpc__auth_tooweak(task);
                 pr_warn("RPC: server %s requires stronger authentication.\n",