[PATCH v12 08/24] SUNRPC: add rpcauth_map_clnt_to_svc_cred_local

[Mike Snitzer <snitzer@kernel.org>]

From: Weston Andros Adamson <dros@primarydata.com>

Add new funtion rpcauth_map_clnt_to_svc_cred_local which maps a
generic cred to a svc_cred suitable for use in nfsd.

This is needed by the localio code to map nfs client creds to nfs
server credentials.

Following from net/sunrpc/auth_unix.c:unx_marshal() it is clear that
->fsuid and ->fsgid must be used (rather than ->uid and ->gid).  In
addition, these uid and gid must be translated with from_kuid_munged()
so local client uses correct uid and gid when acting as local server.

Suggested-by: NeilBrown <neilb@suse.de> # to approximate unx_marshal()
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Co-developed-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
 include/linux/sunrpc/auth.h |  4 ++++
 net/sunrpc/auth.c           | 22 ++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 61e58327b1aa..4cfb68f511db 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -11,6 +11,7 @@
 #define _LINUX_SUNRPC_AUTH_H
 
 #include <linux/sunrpc/sched.h>
+#include <linux/sunrpc/svcauth.h>
 #include <linux/sunrpc/msg_prot.h>
 #include <linux/sunrpc/xdr.h>
 
@@ -184,6 +185,9 @@ int			rpcauth_uptodatecred(struct rpc_task *);
 int			rpcauth_init_credcache(struct rpc_auth *);
 void			rpcauth_destroy_credcache(struct rpc_auth *);
 void			rpcauth_clear_credcache(struct rpc_cred_cache *);
+void			rpcauth_map_clnt_to_svc_cred_local(struct rpc_clnt *clnt,
+							   const struct cred *,
+							   struct svc_cred *);
 char *			rpcauth_stringify_acceptor(struct rpc_cred *);
 
 static inline
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 04534ea537c8..3b6d91b36589 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -17,6 +17,7 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/gss_api.h>
 #include <linux/spinlock.h>
+#include <linux/user_namespace.h>
 
 #include <trace/events/sunrpc.h>
 
@@ -308,6 +309,27 @@ rpcauth_init_credcache(struct rpc_auth *auth)
 }
 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
 
+void
+rpcauth_map_clnt_to_svc_cred_local(struct rpc_clnt *clnt,
+				   const struct cred *cred,
+				   struct svc_cred *svc)
+{
+	struct user_namespace *userns = clnt->cl_cred ?
+		clnt->cl_cred->user_ns : &init_user_ns;
+
+	memset(svc, 0, sizeof(struct svc_cred));
+
+	svc->cr_uid = KUIDT_INIT(from_kuid_munged(userns, cred->fsuid));
+	svc->cr_gid = KGIDT_INIT(from_kgid_munged(userns, cred->fsgid));
+	svc->cr_flavor = clnt->cl_auth->au_flavor;
+	if (cred->group_info)
+		svc->cr_group_info = get_group_info(cred->group_info);
+	/* These aren't relevant for local (network is bypassed) */
+	svc->cr_principal = NULL;
+	svc->cr_gss_mech = NULL;
+}
+EXPORT_SYMBOL_GPL(rpcauth_map_clnt_to_svc_cred_local);
+
 char *
 rpcauth_stringify_acceptor(struct rpc_cred *cred)
 {
-- 
2.44.0