NFS: Convert NFSv2 to use the container user namespace

When mapping NFS identities, we want to substitute for the uids and
gids on the wire as we would for the AUTH_UNIX creds.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs2xdr.c

@@ -76,6 +76,20 @@ static int nfs_stat_to_errno(enum nfs_stat);
  * or decoded inline.
  */
 
+static struct user_namespace *rpc_userns(const struct rpc_clnt *clnt)
+{
+	if (clnt && clnt->cl_cred)
+		return clnt->cl_cred->user_ns;
+	return &init_user_ns;
+}
+
+static struct user_namespace *rpc_rqst_userns(const struct rpc_rqst *rqstp)
+{
+	if (rqstp->rq_task)
+		return rpc_userns(rqstp->rq_task->tk_client);
+	return &init_user_ns;
+}
+
 /*
  *	typedef opaque	nfsdata<>;
  */
@@ -248,7 +262,8 @@ static __be32 *xdr_decode_time(__be32 *p, struct timespec *timep)
  *	};
  *
  */
-static int decode_fattr(struct xdr_stream *xdr, struct nfs_fattr *fattr)
+static int decode_fattr(struct xdr_stream *xdr, struct nfs_fattr *fattr,
+		struct user_namespace *userns)
 {
 	u32 rdev, type;
 	__be32 *p;
@@ -263,10 +278,10 @@ static int decode_fattr(struct xdr_stream *xdr, struct nfs_fattr *fattr)
 
 	fattr->mode = be32_to_cpup(p++);
 	fattr->nlink = be32_to_cpup(p++);
-	fattr->uid = make_kuid(&init_user_ns, be32_to_cpup(p++));
+	fattr->uid = make_kuid(userns, be32_to_cpup(p++));
 	if (!uid_valid(fattr->uid))
 		goto out_uid;
-	fattr->gid = make_kgid(&init_user_ns, be32_to_cpup(p++));
+	fattr->gid = make_kgid(userns, be32_to_cpup(p++));
 	if (!gid_valid(fattr->gid))
 		goto out_gid;
 		
@@ -321,7 +336,8 @@ static __be32 *xdr_time_not_set(__be32 *p)
 	return p;
 }
 
-static void encode_sattr(struct xdr_stream *xdr, const struct iattr *attr)
+static void encode_sattr(struct xdr_stream *xdr, const struct iattr *attr,
+		struct user_namespace *userns)
 {
 	struct timespec ts;
 	__be32 *p;
@@ -333,11 +349,11 @@ static void encode_sattr(struct xdr_stream *xdr, const struct iattr *attr)
 	else
 		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
 	if (attr->ia_valid & ATTR_UID)
-		*p++ = cpu_to_be32(from_kuid(&init_user_ns, attr->ia_uid));
+		*p++ = cpu_to_be32(from_kuid_munged(userns, attr->ia_uid));
 	else
 		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
 	if (attr->ia_valid & ATTR_GID)
-		*p++ = cpu_to_be32(from_kgid(&init_user_ns, attr->ia_gid));
+		*p++ = cpu_to_be32(from_kgid_munged(userns, attr->ia_gid));
 	else
 		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
 	if (attr->ia_valid & ATTR_SIZE)
@@ -451,7 +467,8 @@ static int decode_path(struct xdr_stream *xdr)
  *	};
  */
 static int decode_attrstat(struct xdr_stream *xdr, struct nfs_fattr *result,
-			   __u32 *op_status)
+			   __u32 *op_status,
+			   struct user_namespace *userns)
 {
 	enum nfs_stat status;
 	int error;
@@ -463,7 +480,7 @@ static int decode_attrstat(struct xdr_stream *xdr, struct nfs_fattr *result,
 		*op_status = status;
 	if (status != NFS_OK)
 		goto out_default;
-	error = decode_fattr(xdr, result);
+	error = decode_fattr(xdr, result, userns);
 out:
 	return error;
 out_default:
@@ -498,19 +515,21 @@ static void encode_diropargs(struct xdr_stream *xdr, const struct nfs_fh *fh,
  *		void;
  *	};
  */
-static int decode_diropok(struct xdr_stream *xdr, struct nfs_diropok *result)
+static int decode_diropok(struct xdr_stream *xdr, struct nfs_diropok *result,
+		struct user_namespace *userns)
 {
 	int error;
 
 	error = decode_fhandle(xdr, result->fh);
 	if (unlikely(error))
 		goto out;
-	error = decode_fattr(xdr, result->fattr);
+	error = decode_fattr(xdr, result->fattr, userns);
 out:
 	return error;
 }
 
-static int decode_diropres(struct xdr_stream *xdr, struct nfs_diropok *result)
+static int decode_diropres(struct xdr_stream *xdr, struct nfs_diropok *result,
+		struct user_namespace *userns)
 {
 	enum nfs_stat status;
 	int error;
@@ -520,7 +539,7 @@ static int decode_diropres(struct xdr_stream *xdr, struct nfs_diropok *result)
 		goto out;
 	if (status != NFS_OK)
 		goto out_default;
-	error = decode_diropok(xdr, result);
+	error = decode_diropok(xdr, result, userns);
 out:
 	return error;
 out_default:
@@ -559,7 +578,7 @@ static void nfs2_xdr_enc_sattrargs(struct rpc_rqst *req,
 	const struct nfs_sattrargs *args = data;
 
 	encode_fhandle(xdr, args->fh);
-	encode_sattr(xdr, args->sattr);
+	encode_sattr(xdr, args->sattr, rpc_rqst_userns(req));
 }
 
 static void nfs2_xdr_enc_diropargs(struct rpc_rqst *req,
@@ -674,7 +693,7 @@ static void nfs2_xdr_enc_createargs(struct rpc_rqst *req,
 	const struct nfs_createargs *args = data;
 
 	encode_diropargs(xdr, args->fh, args->name, args->len);
-	encode_sattr(xdr, args->sattr);
+	encode_sattr(xdr, args->sattr, rpc_rqst_userns(req));
 }
 
 static void nfs2_xdr_enc_removeargs(struct rpc_rqst *req,
@@ -741,7 +760,7 @@ static void nfs2_xdr_enc_symlinkargs(struct rpc_rqst *req,
 
 	encode_diropargs(xdr, args->fromfh, args->fromname, args->fromlen);
 	encode_path(xdr, args->pages, args->pathlen);
-	encode_sattr(xdr, args->sattr);
+	encode_sattr(xdr, args->sattr, rpc_rqst_userns(req));
 }
 
 /*
@@ -803,13 +822,13 @@ static int nfs2_xdr_dec_stat(struct rpc_rqst *req, struct xdr_stream *xdr,
 static int nfs2_xdr_dec_attrstat(struct rpc_rqst *req, struct xdr_stream *xdr,
 				 void *result)
 {
-	return decode_attrstat(xdr, result, NULL);
+	return decode_attrstat(xdr, result, NULL, rpc_rqst_userns(req));
 }
 
 static int nfs2_xdr_dec_diropres(struct rpc_rqst *req, struct xdr_stream *xdr,
 				 void *result)
 {
-	return decode_diropres(xdr, result);
+	return decode_diropres(xdr, result, rpc_rqst_userns(req));
 }
 
 /*
@@ -864,7 +883,7 @@ static int nfs2_xdr_dec_readres(struct rpc_rqst *req, struct xdr_stream *xdr,
 	result->op_status = status;
 	if (status != NFS_OK)
 		goto out_default;
-	error = decode_fattr(xdr, result->fattr);
+	error = decode_fattr(xdr, result->fattr, rpc_rqst_userns(req));
 	if (unlikely(error))
 		goto out;
 	error = decode_nfsdata(xdr, result);
@@ -881,7 +900,8 @@ static int nfs2_xdr_dec_writeres(struct rpc_rqst *req, struct xdr_stream *xdr,
 
 	/* All NFSv2 writes are "file sync" writes */
 	result->verf->committed = NFS_FILE_SYNC;
-	return decode_attrstat(xdr, result->fattr, &result->op_status);
+	return decode_attrstat(xdr, result->fattr, &result->op_status,
+			rpc_rqst_userns(req));
 }
 
 /**