Allow users access to unpriviledged zpool/zfs commands

The following zpool/zfs commands should be runable as a normal
non-priviledged user.

  * zpool list|iostat|status|get
  * zfs list|get

Adding this functionality primarily required implementing the
secpolicy_* functions by mapping them to the equivilant Linux
capabilities.  Since the VFS already enforces several of these
checks it was not nessisary to implement them all.

While the mapping operation is straight forward the implementation
was complicated by the fact that the kernel `capability()` function
only allows you to check your current content.  This poses an issue
for the existing ZFS code which expects to be able to check a cred
in any context.  To resolve the issue `secpolicy_zfs()` checks are
now made in the original cred context, if they pass a kcred is then
provided for latter use by the sync task.

In order to verify this functionality workss as designed the ZFS
Test Suite cli_user/* tests have all been enabled.  These tests
are run as a normal user and are used to verify permissions are
enforced.

The `zpool_create_001_neg` and `zpool_add_001_neg` test cases were
slightly modified for Linux.  They now allow a normal user to run
these commands in dry-run mode since no escalated priviledges are
required.

Two minor bug fixes were required for test-running.py.  First, the
Timer() object cannot be safely created in a `try:` block when there
is an unconditional `finally` block which references it.  Second,
when running as a normal user also check for scripts using the
both the .ksh and .sh suffixes.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #362

cmd/zpool/zpool_main.c

@@ -42,7 +42,6 @@
 #include <string.h>
 #include <strings.h>
 #include <unistd.h>
-#include <priv.h>
 #include <pwd.h>
 #include <zone.h>
 #include <zfs_prop.h>
@@ -2252,21 +2251,21 @@ zpool_do_import(int argc, char **argv)
 			(void) fprintf(stderr, gettext("too many arguments\n"));
 			usage(B_FALSE);
 		}
+	}
 
-		/*
-		 * Check for the SYS_CONFIG privilege.  We do this explicitly
-		 * here because otherwise any attempt to discover pools will
-		 * silently fail.
-		 */
-		if (argc == 0 && !priv_ineffect(PRIV_SYS_CONFIG)) {
-			(void) fprintf(stderr, gettext("cannot "
-			    "discover pools: permission denied\n"));
-			if (searchdirs != NULL)
-				free(searchdirs);
+	/*
+	 * Check for the effective uid.  We do this explicitly
+	 * here because otherwise any attempt to discover pools will
+	 * silently fail.
+	 */
+	if (argc == 0 && geteuid() != 0) {
+		(void) fprintf(stderr, gettext("cannot "
+		    "discover pools: permission denied\n"));
+		if (searchdirs != NULL)
+			free(searchdirs);
 
-			nvlist_free(policy);
-			return (1);
-		}
+		nvlist_free(policy);
+		return (1);
 	}
 
 	/*

include/sys/Makefile.am

@@ -38,6 +38,7 @@ COMMON_H = \
 	$(top_srcdir)/include/sys/multilist.h \
 	$(top_srcdir)/include/sys/nvpair.h \
 	$(top_srcdir)/include/sys/nvpair_impl.h \
+	$(top_srcdir)/include/sys/policy.h \
 	$(top_srcdir)/include/sys/range_tree.h \
 	$(top_srcdir)/include/sys/refcount.h \
 	$(top_srcdir)/include/sys/rrwlock.h \

include/sys/policy.h

@@ -0,0 +1,60 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2015, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2016, Lawrence Livermore National Security, LLC.
+ */
+
+#ifndef _SYS_POLICY_H
+#define	_SYS_POLICY_H
+
+#ifdef _KERNEL
+
+#include <sys/cred.h>
+#include <sys/types.h>
+#include <sys/xvattr.h>
+#include <sys/zpl.h>
+
+int secpolicy_nfs(const cred_t *);
+int secpolicy_sys_config(const cred_t *, boolean_t);
+int secpolicy_vnode_access2(const cred_t *, struct inode *,
+    uid_t, mode_t, mode_t);
+int secpolicy_vnode_any_access(const cred_t *, struct inode *, uid_t);
+int secpolicy_vnode_chown(const cred_t *, uid_t);
+int secpolicy_vnode_create_gid(const cred_t *);
+int secpolicy_vnode_remove(const cred_t *);
+int secpolicy_vnode_setdac(const cred_t *, uid_t);
+int secpolicy_vnode_setid_retain(const cred_t *, boolean_t);
+int secpolicy_vnode_setids_setgids(const cred_t *, gid_t);
+int secpolicy_zinject(const cred_t *);
+int secpolicy_zfs(const cred_t *);
+void secpolicy_setid_clear(vattr_t *, cred_t *);
+int secpolicy_setid_setsticky_clear(struct inode *, vattr_t *,
+    const vattr_t *, cred_t *);
+int secpolicy_xvattr(xvattr_t *, uid_t, cred_t *, vtype_t);
+int secpolicy_vnode_setattr(cred_t *, struct inode *, struct vattr *,
+    const struct vattr *, int, int (void *, int, cred_t *), void *);
+int secpolicy_basic_link(const cred_t *);
+
+#endif /* _KERNEL */
+#endif /* _SYS_POLICY_H */

include/sys/zfs_context.h

@@ -734,6 +734,7 @@ extern int zfs_secpolicy_snapshot_perms(const char *name, cred_t *cr);
 extern int zfs_secpolicy_rename_perms(const char *from, const char *to,
     cred_t *cr);
 extern int zfs_secpolicy_destroy_perms(const char *name, cred_t *cr);
+extern int secpolicy_zfs(const cred_t *cr);
 extern zoneid_t getzoneid(void);
 
 /* SID stuff */

lib/libspl/include/Makefile.am

@@ -12,7 +12,6 @@ libspl_HEADERS = \
 	$(top_srcdir)/lib/libspl/include/limits.h \
 	$(top_srcdir)/lib/libspl/include/locale.h \
 	$(top_srcdir)/lib/libspl/include/note.h \
-	$(top_srcdir)/lib/libspl/include/priv.h \
 	$(top_srcdir)/lib/libspl/include/statcommon.h \
 	$(top_srcdir)/lib/libspl/include/stdio.h \
 	$(top_srcdir)/lib/libspl/include/stdlib.h \

lib/libzfs/libzfs_dataset.c

@@ -43,7 +43,6 @@
 #include <fcntl.h>
 #include <sys/mntent.h>
 #include <sys/mount.h>
-#include <priv.h>
 #include <pwd.h>
 #include <grp.h>
 #include <stddef.h>

lib/libzpool/kernel.c

@@ -1260,6 +1260,12 @@ zfs_secpolicy_destroy_perms(const char *name, cred_t *cr)
 	return (0);
 }
 
+int
+secpolicy_zfs(const cred_t *cr)
+{
+	return (0);
+}
+
 ksiddomain_t *
 ksid_lookupdomain(const char *dom)
 {

module/zfs/Makefile.in

@@ -42,6 +42,7 @@ $(MODULE)-objs += lzjb.o
 $(MODULE)-objs += lz4.o
 $(MODULE)-objs += metaslab.o
 $(MODULE)-objs += multilist.o
+$(MODULE)-objs += policy.o
 $(MODULE)-objs += range_tree.o
 $(MODULE)-objs += refcount.o
 $(MODULE)-objs += rrwlock.o

module/zfs/dmu_objset.c

@@ -52,6 +52,7 @@
 #include <sys/zfs_onexit.h>
 #include <sys/dsl_destroy.h>
 #include <sys/vdev.h>
+#include <sys/policy.h>
 
 /*
  * Needed to close a window in dnode_move() that allows the objset to be freed
@@ -880,9 +881,14 @@ dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg)
 {
 	dmu_objset_create_arg_t doca;
+	int error;
+
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
 
 	doca.doca_name = name;
-	doca.doca_cred = CRED();
+	doca.doca_cred = kcred;
 	doca.doca_flags = flags;
 	doca.doca_userfunc = func;
 	doca.doca_userarg = arg;
@@ -974,10 +980,15 @@ int
 dmu_objset_clone(const char *clone, const char *origin)
 {
 	dmu_objset_clone_arg_t doca;
+	int error;
+
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
 
 	doca.doca_clone = clone;
 	doca.doca_origin = origin;
-	doca.doca_cred = CRED();
+	doca.doca_cred = kcred;
 
 	return (dsl_sync_task(clone,
 	    dmu_objset_clone_check, dmu_objset_clone_sync, &doca,

module/zfs/dmu_send.c

@@ -56,6 +56,7 @@
 #include <sys/zfeature.h>
 #include <sys/bqueue.h>
 #include <sys/zvol.h>
+#include <sys/policy.h>
 
 /* Set this tunable to TRUE to replace corrupt data with 0x2f5baddb10c */
 int zfs_send_corrupt_data = B_FALSE;
@@ -1405,13 +1406,18 @@ dmu_recv_begin(char *tofs, char *tosnap, struct drr_begin *drrb,
 {
 	dmu_recv_begin_arg_t drba = { 0 };
 	dmu_replay_record_t *drr;
+	int error;
+
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
 
 	bzero(drc, sizeof (dmu_recv_cookie_t));
 	drc->drc_drrb = drrb;
 	drc->drc_tosnap = tosnap;
 	drc->drc_tofs = tofs;
 	drc->drc_force = force;
-	drc->drc_cred = CRED();
+	drc->drc_cred = kcred;
 
 	if (drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC))
 		drc->drc_byteswap = B_TRUE;
@@ -1441,7 +1447,7 @@ dmu_recv_begin(char *tofs, char *tosnap, struct drr_begin *drrb,
 
 	drba.drba_origin = origin;
 	drba.drba_cookie = drc;
-	drba.drba_cred = CRED();
+	drba.drba_cred = kcred;
 
 	return (dsl_sync_task(tofs, dmu_recv_begin_check, dmu_recv_begin_sync,
 	    &drba, 5, ZFS_SPACE_CHECK_NORMAL));

module/zfs/dsl_dataset.c

@@ -51,6 +51,7 @@
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_userhold.h>
 #include <sys/dsl_bookmark.h>
+#include <sys/policy.h>
 
 /*
  * The SPA supports block sizes up to 16MB.  However, very large blocks
@@ -1456,6 +1457,10 @@ dsl_dataset_snapshot(nvlist_t *snaps, nvlist_t *props, nvlist_t *errors)
 	needsuspend = (spa_version(spa) < SPA_VERSION_FAST_SNAP);
 	spa_close(spa, FTAG);
 
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
+
 	if (needsuspend) {
 		suspended = fnvlist_alloc();
 		for (pair = nvlist_next_nvpair(snaps, NULL); pair != NULL;
@@ -1483,7 +1488,7 @@ dsl_dataset_snapshot(nvlist_t *snaps, nvlist_t *props, nvlist_t *errors)
 	ddsa.ddsa_snaps = snaps;
 	ddsa.ddsa_props = props;
 	ddsa.ddsa_errors = errors;
-	ddsa.ddsa_cr = CRED();
+	ddsa.ddsa_cr = kcred;
 
 	if (error == 0) {
 		error = dsl_sync_task(firstname, dsl_dataset_snapshot_check,
@@ -2671,9 +2676,13 @@ dsl_dataset_promote(const char *name, char *conflsnap)
 	if (error != 0)
 		return (error);
 
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
+
 	ddpa.ddpa_clonename = name;
 	ddpa.err_ds = conflsnap;
-	ddpa.cr = CRED();
+	ddpa.cr = kcred;
 
 	return (dsl_sync_task(name, dsl_dataset_promote_check,
 	    dsl_dataset_promote_sync, &ddpa,

module/zfs/dsl_dir.c

@@ -1923,10 +1923,15 @@ int
 dsl_dir_rename(const char *oldname, const char *newname)
 {
 	dsl_dir_rename_arg_t ddra;
+	int error;
+
+	error = secpolicy_zfs(CRED());
+	if (error)
+		return (SET_ERROR(error));
 
 	ddra.ddra_oldname = oldname;
 	ddra.ddra_newname = newname;
-	ddra.ddra_cred = CRED();
+	ddra.ddra_cred = kcred;
 
 	return (dsl_sync_task(oldname,
 	    dsl_dir_rename_check, dsl_dir_rename_sync, &ddra,