SUNRPC: Cache the process user cred in the RPC server listener

In order to be able to interpret uids and gids correctly in knfsd, we
should cache the user namespace of the process that created the RPC
server's listener. To do so, we refcount the credential of that process.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 11 insertions, 5 deletions

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 61530b1b7754..b76ee83d4d43 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -136,6 +136,7 @@ static void svc_xprt_free(struct kref *kref)
 	struct module *owner = xprt->xpt_class->xcl_owner;
 	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags))
 		svcauth_unix_info_release(xprt);
+	put_cred(xprt->xpt_cred);
 	put_net(xprt->xpt_net);
 	/* See comment on corresponding get in xs_setup_bc_tcp(): */
 	if (xprt->xpt_bc_xprt)
@@ -252,7 +253,8 @@ void svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *new)
 
 static int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 			    struct net *net, const int family,
-			    const unsigned short port, int flags)
+			    const unsigned short port, int flags,
+			    const struct cred *cred)
 {
 	struct svc_xprt_class *xcl;
 
@@ -273,6 +275,7 @@ static int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 			module_put(xcl->xcl_owner);
 			return PTR_ERR(newxprt);
 		}
+		newxprt->xpt_cred = get_cred(cred);
 		svc_add_new_perm_xprt(serv, newxprt);
 		newport = svc_xprt_local_port(newxprt);
 		return newport;
@@ -286,15 +289,16 @@ static int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 
 int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
 		    struct net *net, const int family,
-		    const unsigned short port, int flags)
+		    const unsigned short port, int flags,
+		    const struct cred *cred)
 {
 	int err;
 
 	dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
-	err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
+	err = _svc_create_xprt(serv, xprt_name, net, family, port, flags, cred);
 	if (err == -EPROTONOSUPPORT) {
 		request_module("svc%s", xprt_name);
-		err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
+		err = _svc_create_xprt(serv, xprt_name, net, family, port, flags, cred);
 	}
 	if (err < 0)
 		dprintk("svc: transport %s not found, err %d\n",
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 43590a968b73..540fde2804d0 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1332,13 +1332,14 @@ EXPORT_SYMBOL_GPL(svc_alien_sock);
  * @fd: file descriptor of the new listener
  * @name_return: pointer to buffer to fill in with name of listener
  * @len: size of the buffer
+ * @cred: credential
  *
  * Fills in socket name and returns positive length of name if successful.
  * Name is terminated with '\n'.  On error, returns a negative errno
  * value.
  */
 int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
-		const size_t len)
+		const size_t len, const struct cred *cred)
 {
 	int err = 0;
 	struct socket *so = sockfd_lookup(fd, &err);
@@ -1371,6 +1372,7 @@ int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
 	salen = kernel_getsockname(svsk->sk_sock, sin);
 	if (salen >= 0)
 		svc_xprt_set_local(&svsk->sk_xprt, sin, salen);
+	svsk->sk_xprt.xpt_cred = get_cred(cred);
 	svc_add_new_perm_xprt(serv, &svsk->sk_xprt);
 	return svc_one_sock_name(svsk, name_return, len);
 out: