sunrpc: on successful gss error pipe write, don't return error

When handling the gssd downcall, the kernel should distinguish between a
successful downcall that contains an error code and a failed downcall
(i.e. where the parsing failed or some other sort of problem occurred).

In the former case, gss_pipe_downcall should be returning the number of
bytes written to the pipe instead of an error. In the event of other
errors, we generally want the initiating task to retry the upcall so
we set msg.errno to -EAGAIN. An unexpected error code here is a bug
however, so BUG() in that case.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 3c3c50f38a1c4a773113db4f5388b27bc85453f8..66cb89c18347fdef7fe0271fefce3baa739fc2b6 100644 (file)
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -644,7 +644,22 @@ gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
        p = gss_fill_context(p, end, ctx, gss_msg->auth->mech);
        if (IS_ERR(p)) {
                err = PTR_ERR(p);
-               gss_msg->msg.errno = (err == -EAGAIN) ? -EAGAIN : -EACCES;
+               switch (err) {
+               case -EACCES:
+                       gss_msg->msg.errno = err;
+                       err = mlen;
+                       break;
+               case -EFAULT:
+               case -ENOMEM:
+               case -EINVAL:
+               case -ENOSYS:
+                       gss_msg->msg.errno = -EAGAIN;
+                       break;
+               default:
+                       printk(KERN_CRIT "%s: bad return from "
+                               "gss_fill_context: %ld\n", __func__, err);
+                       BUG();
+               }
                goto err_release_msg;
        }
        gss_msg->ctx = gss_get_ctx(ctx);