NFSv4: Send unmapped uid/gids to the server when using auth_sys

The new behaviour is enabled using the new module parameter
'nfs4_disable_idmapping'.

Note that if the server rejects an unmapped uid or gid, then
the client will automatically switch back to using the idmapper.

Signed-off-by: Trond Myklebust <[email protected]>

Author: Trond Myklebust

Documentation/kernel-parameters.txt

@@ -1580,6 +1580,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			of returning the full 64-bit number.
 			The default is to return 64-bit inode numbers.
 
+	nfs.nfs4_disable_idmapping=
+			[NFSv4] When set, this option disables the NFSv4
+			idmapper on the client, but only if the mount
+			is using the 'sec=sys' security flavour. This may
+			make migration from legacy NFSv2/v3 systems easier
+			provided that the server has the appropriate support.
+			The default is to always enable NFSv4 idmapping.
+
 	nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take
 			when a NMI is triggered.
 			Format: [state][,regs][,debounce][,die]

fs/nfs/client.c

@@ -81,6 +81,11 @@ static int nfs_get_cb_ident_idr(struct nfs_client *clp, int minorversion)
 }
 #endif /* CONFIG_NFS_V4 */
 
+/*
+ * Turn off NFSv4 uid/gid mapping when using AUTH_SYS
+ */
+static int nfs4_disable_idmapping = 0;
+
 /*
  * RPC cruft for NFS
  */
@@ -1567,6 +1572,13 @@ static int nfs4_init_server(struct nfs_server *server,
 	if (error < 0)
 		goto error;
 
+	/*
+	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
+	 * authentication.
+	 */
+	if (nfs4_disable_idmapping && data->auth_flavors[0] == RPC_AUTH_UNIX)
+		server->caps |= NFS_CAP_UIDGID_NOMAP;
+
 	if (data->rsize)
 		server->rsize = nfs_block_size(data->rsize, NULL);
 	if (data->wsize)
@@ -1984,3 +1996,7 @@ void nfs_fs_proc_exit(void)
 }
 
 #endif /* CONFIG_PROC_FS */
+
+module_param(nfs4_disable_idmapping, bool, 0644);
+MODULE_PARM_DESC(nfs4_disable_idmapping,
+		"Turn off NFSv4 idmapping when using 'sec=sys'");

fs/nfs/idmap.c

@@ -61,6 +61,9 @@ static int nfs_map_numeric_to_string(__u32 id, char *buf, size_t buflen)
 
 #include <linux/slab.h>
 #include <linux/cred.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/nfs4.h>
+#include <linux/nfs_fs_sb.h>
 #include <linux/nfs_idmap.h>
 #include <linux/keyctl.h>
 #include <linux/key-type.h>
@@ -257,17 +260,20 @@ int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size
 
 int nfs_map_uid_to_name(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
 {
-	int ret;
-	ret = nfs_idmap_lookup_name(uid, "user", buf, buflen);
+	int ret = -EINVAL;
+
+	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
+		ret = nfs_idmap_lookup_name(uid, "user", buf, buflen);
 	if (ret < 0)
 		ret = nfs_map_numeric_to_string(uid, buf, buflen);
 	return ret;
 }
 int nfs_map_gid_to_group(const struct nfs_server *server, __u32 gid, char *buf, size_t buflen)
 {
-	int ret;
+	int ret = -EINVAL;
 
-	ret = nfs_idmap_lookup_name(gid, "group", buf, buflen);
+	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
+		ret = nfs_idmap_lookup_name(gid, "group", buf, buflen);
 	if (ret < 0)
 		ret = nfs_map_numeric_to_string(gid, buf, buflen);
 	return ret;
@@ -750,19 +756,21 @@ int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size
 int nfs_map_uid_to_name(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
-	int ret;
+	int ret = -EINVAL;
 
-	ret = nfs_idmap_name(idmap, &idmap->idmap_user_hash, uid, buf);
+	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
+		ret = nfs_idmap_name(idmap, &idmap->idmap_user_hash, uid, buf);
 	if (ret < 0)
 		ret = nfs_map_numeric_to_string(uid, buf, buflen);
 	return ret;
 }
 int nfs_map_gid_to_group(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
 {
 	struct idmap *idmap = server->nfs_client->cl_idmap;
-	int ret;
+	int ret = -EINVAL;
 
-	ret = nfs_idmap_name(idmap, &idmap->idmap_group_hash, uid, buf);
+	if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
+		ret = nfs_idmap_name(idmap, &idmap->idmap_group_hash, uid, buf);
 	if (ret < 0)
 		ret = nfs_map_numeric_to_string(uid, buf, buflen);
 	return ret;

fs/nfs/nfs4proc.c

@@ -244,7 +244,7 @@ static int nfs4_delay(struct rpc_clnt *clnt, long *timeout)
 /* This is the error handling routine for processes that are allowed
  * to sleep.
  */
-static int nfs4_handle_exception(const struct nfs_server *server, int errorcode, struct nfs4_exception *exception)
+static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struct nfs4_exception *exception)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs4_state *state = exception->state;
@@ -296,6 +296,19 @@ static int nfs4_handle_exception(const struct nfs_server *server, int errorcode,
 				break;
 		case -NFS4ERR_OLD_STATEID:
 			exception->retry = 1;
+			break;
+		case -NFS4ERR_BADOWNER:
+			/* The following works around a Linux server bug! */
+		case -NFS4ERR_BADNAME:
+			if (server->caps & NFS_CAP_UIDGID_NOMAP) {
+				server->caps &= ~NFS_CAP_UIDGID_NOMAP;
+				exception->retry = 1;
+				printk(KERN_WARNING "NFS: v4 server %s "
+						"does not accept raw "
+						"uid/gids. "
+						"Reenabling the idmapper.\n",
+						server->nfs_client->cl_hostname);
+			}
 	}
 	/* We failed to handle the error */
 	return nfs4_map_errors(ret);

include/linux/nfs_fs_sb.h

@@ -177,6 +177,7 @@ struct nfs_server {
 #define NFS_CAP_CTIME		(1U << 12)
 #define NFS_CAP_MTIME		(1U << 13)
 #define NFS_CAP_POSIX_LOCK	(1U << 14)
+#define NFS_CAP_UIDGID_NOMAP	(1U << 15)
 
 
 /* maximum number of slots to use */