Fix mount helper

Several issues related to strange mount/umount behavior were reported
and this commit should address most of them.  The original idea was
to put in place a zfs mount helper (mount.zfs).  This helper is used
to enforce 'legacy' mount behavior, and perform any extra mount argument
processing (selinux, zfsutil, etc).  This helper wasn't ready for the
0.6.0-rc1 release but with this change it's functional but needs to
extensively tested.

This change addresses the following open issues.
Closes #101
Closes #107
Closes #113
Closes #115
Closes #119

1 files changed, 45 insertions, 425 deletions

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index f21c36b81..32f85b1e0 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -3827,371 +3827,6 @@ zfs_do_python(int argc, char **argv)
 	return (-1);
 }
 
-typedef struct option_map {
-	const char *name;
-	int mask;
-} option_map_t;
-
-static const option_map_t option_map[] = {
-	/* Canonicalized filesystem independent options from mount(8) */
-	{ MNTOPT_NOAUTO,	MS_COMMENT	},
-	{ MNTOPT_DEFAULTS,	MS_COMMENT	},
-	{ MNTOPT_NODEVICES,	MS_NODEV	},
-	{ MNTOPT_DIRSYNC,	MS_DIRSYNC	},
-	{ MNTOPT_NOEXEC,	MS_NOEXEC	},
-	{ MNTOPT_GROUP,		MS_GROUP	},
-	{ MNTOPT_NETDEV,	MS_COMMENT	},
-	{ MNTOPT_NOFAIL,	MS_COMMENT	},
-	{ MNTOPT_NOSUID,	MS_NOSUID	},
-	{ MNTOPT_OWNER,		MS_OWNER	},
-	{ MNTOPT_REMOUNT,	MS_REMOUNT	},
-	{ MNTOPT_RO,		MS_RDONLY	},
-	{ MNTOPT_SYNC,		MS_SYNCHRONOUS	},
-	{ MNTOPT_USER,		MS_USERS	},
-	{ MNTOPT_USERS,		MS_USERS	},
-#ifdef MS_NOATIME
-	{ MNTOPT_NOATIME,	MS_NOATIME	},
-#endif
-#ifdef MS_NODIRATIME
-	{ MNTOPT_NODIRATIME,	MS_NODIRATIME	},
-#endif
-#ifdef MS_RELATIME
-	{ MNTOPT_RELATIME,	MS_RELATIME	},
-#endif
-#ifdef MS_STRICTATIME
-	{ MNTOPT_DFRATIME,	MS_STRICTATIME	},
-#endif
-#ifdef HAVE_SELINUX
-	{ MNTOPT_CONTEXT,	MS_COMMENT	},
-	{ MNTOPT_FSCONTEXT,	MS_COMMENT	},
-	{ MNTOPT_DEFCONTEXT,	MS_COMMENT	},
-	{ MNTOPT_ROOTCONTEXT,	MS_COMMENT	},
-#endif
-#ifdef MS_I_VERSION
-	{ MNTOPT_IVERSION,	MS_I_VERSION	},
-#endif
-#ifdef MS_MANDLOCK
-	{ MNTOPT_NBMAND,	MS_MANDLOCK	},
-#endif
-	/* Valid options not found in mount(8) */
-	{ MNTOPT_BIND,		MS_BIND		},
-#ifdef MS_REC
-	{ MNTOPT_RBIND,		MS_BIND|MS_REC	},
-#endif
-	{ MNTOPT_COMMENT,	MS_COMMENT	},
-	{ MNTOPT_BOOTWAIT,	MS_COMMENT	},
-	{ MNTOPT_NOBOOTWAIT,	MS_COMMENT	},
-	{ MNTOPT_OPTIONAL,	MS_COMMENT	},
-	{ MNTOPT_SHOWTHROUGH,	MS_COMMENT	},
-#ifdef MS_NOSUB
-	{ MNTOPT_NOSUB,		MS_NOSUB	},
-#endif
-#ifdef MS_SILENT
-	{ MNTOPT_QUIET,		MS_SILENT	},
-#endif
-	/* Custom zfs options */
-	{ MNTOPT_NOXATTR,	MS_COMMENT	},
-	{ NULL,			0		} };
-
-/*
- * Break the mount option in to a name/value pair.  The name is
- * validated against the option map and mount flags set accordingly.
- */
-static int
-parse_option(char *mntopt, unsigned long *mntflags, int sloppy)
-{
-	const option_map_t *opt;
-	char *ptr, *name, *value = NULL;
-	int rc = 0;
-
-	name = strdup(mntopt);
-	if (name == NULL)
-		return (ENOMEM);
-
-	for (ptr = name; ptr && *ptr; ptr++) {
-		if (*ptr == '=') {
-			*ptr = '\0';
-			value = ptr+1;
-			break;
-		}
-	}
-
-	for (opt = option_map; opt->name != NULL; opt++) {
-		if (strncmp(name, opt->name, strlen(name)) == 0) {
-			*mntflags |= opt->mask;
-
-			/* MS_USERS implies default user options */
-			if (opt->mask & (MS_USERS))
-				*mntflags |= (MS_NOEXEC|MS_NOSUID|MS_NODEV);
-
-			/* MS_OWNER|MS_GROUP imply default owner options */
-			if (opt->mask & (MS_OWNER | MS_GROUP))
-				*mntflags |= (MS_NOSUID|MS_NODEV);
-
-			rc = 0;
-			goto out;
-		}
-	}
-
-	if (!sloppy)
-		rc = ENOENT;
-out:
-	/* If required further process on the value may be done here */
-	free(name);
-	return (rc);
-}
-
-/*
- * Translate the mount option string in to MS_* mount flags for the
- * kernel vfs.  When sloppy is non-zero unknown options will be ignored
- * otherwise they are considered fatal are copied in to badopt.
- */
-static int
-parse_options(char *mntopts, unsigned long *mntflags, int sloppy, char *badopt)
-{
-	int rc = 0, quote = 0;
-	char *ptr, *opt, *opts;
-
-	opts = strdup(mntopts);
-	if (opts == NULL)
-		return (ENOMEM);
-
-	*mntflags = 0;
-	opt = NULL;
-
-	/*
-	 * Scan through all mount options which must be comma delimited.
-	 * We must be careful to notice regions which are double quoted
-	 * and skip commas in these regions.  Each option is then checked
-	 * to determine if it is a known option.
-	 */
-	for (ptr = opts; ptr && *ptr; ptr++) {
-		if (opt == NULL)
-			opt = ptr;
-
-		if (*ptr == '"')
-			quote = !quote;
-
-		if (quote)
-			continue;
-
-		if ((*ptr == ',') || (*ptr == '\0')) {
-			*ptr = '\0';
-			rc = parse_option(opt, mntflags, sloppy);
-			if (rc) {
-				strcpy(badopt, opt);
-				goto out;
-			}
-
-			opt = NULL;
-		}
-	}
-out:
-	free(opts);
-	return (rc);
-}
-
-/*
- * Called when invoked as /sbin/mount.zfs, mount helper for mount(8).
- */
-static int
-manual_mount(int argc, char **argv)
-{
-	zfs_handle_t *zhp;
-	char legacy[ZFS_MAXPROPLEN];
-	char mntopts[MNT_LINE_MAX] = { '\0' };
-	char badopt[MNT_LINE_MAX] = { '\0' };
-	char *dataset, *mntpoint;
-	unsigned long mntflags;
-	int sloppy = 0, fake = 0, verbose = 0;
-	int rc, c;
-
-	/* check options */
-	while ((c = getopt(argc, argv, "sfnvo:h?")) != -1) {
-		switch (c) {
-		case 's':
-			sloppy = 1;
-			break;
-		case 'f':
-			fake = 1;
-			break;
-		case 'n':
-			/* Ignored, handled by mount(8) */
-			break;
-		case 'v':
-			verbose++;
-			break;
-		case 'o':
-			(void) strlcpy(mntopts, optarg, sizeof (mntopts));
-			break;
-		case 'h':
-		case '?':
-			(void) fprintf(stderr, gettext("Invalid option '%c'\n"),
-			    optopt);
-			(void) fprintf(stderr, gettext("Usage: mount.zfs "
-			    "[-sfnv] [-o options] <dataset> <mountpoint>\n"));
-			return (MOUNT_USAGE);
-		}
-	}
-
-	argc -= optind;
-	argv += optind;
-
-	/* check that we only have two arguments */
-	if (argc != 2) {
-		if (argc == 0)
-			(void) fprintf(stderr, gettext("missing dataset "
-			    "argument\n"));
-		else if (argc == 1)
-			(void) fprintf(stderr,
-			    gettext("missing mountpoint argument\n"));
-		else
-			(void) fprintf(stderr, gettext("too many arguments\n"));
-		(void) fprintf(stderr, "usage: mount <dataset> <mountpoint>\n");
-		return (MOUNT_USAGE);
-	}
-
-	dataset = argv[0];
-	mntpoint = argv[1];
-
-	/* try to open the dataset to access the mount point */
-	if ((zhp = zfs_open(g_zfs, dataset, ZFS_TYPE_FILESYSTEM)) == NULL) {
-		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
-		    "mounted, unable to open the dataset\n"), dataset);
-		return (MOUNT_USAGE);
-	}
-
-	(void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, legacy,
-	    sizeof (legacy), NULL, NULL, 0, B_FALSE);
-
-	zfs_close(zhp);
-
-	/* check for legacy mountpoint or util mount option */
-	if ((!strcmp(legacy, ZFS_MOUNTPOINT_LEGACY) == 0) &&
-	    (strstr(mntopts, MNTOPT_ZFSUTIL) == NULL)) {
-		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
-		    "mounted using 'mount -a -t zfs'\n"), dataset);
-		(void) fprintf(stderr, gettext("Use 'zfs set mountpoint=%s' "
-		    "instead.\n"), mntpoint);
-		(void) fprintf(stderr, gettext("If you must use 'mount -a -t "
-		    "zfs' or /etc/fstab, use 'zfs set mountpoint=legacy'.\n"));
-		(void) fprintf(stderr, gettext("See zfs(8) for more "
-		    "information.\n"));
-		return (MOUNT_USAGE);
-	}
-
-	/* validate mount options and set mntflags */
-	rc = parse_options(mntopts, &mntflags, sloppy, badopt);
-	if (rc) {
-		switch (rc) {
-		case ENOMEM:
-			(void) fprintf(stderr, gettext("filesystem '%s' "
-			    "cannot be mounted due to a memory allocation "
-			    "failure\n"), dataset);
-			return (MOUNT_SYSERR);
-		case EINVAL:
-			(void) fprintf(stderr, gettext("filesystem '%s' "
-			    "cannot be mounted of due to the invalid option "
-			    "'%s'\n"), dataset, badopt);
-			(void) fprintf(stderr, gettext("Use the '-s' option "
-			    "to ignore the bad mount option.\n"));
-			return (MOUNT_USAGE);
-		default:
-			(void) fprintf(stderr, gettext("filesystem '%s' "
-			    "cannot be mounted due to internal error %d\n"),
-			    dataset, rc);
-			return (MOUNT_SOFTWARE);
-		}
-	}
-
-	if (verbose > 2)
-		printf("mount.zfs: dataset: \"%s\", mountpoint: \"%s\" "
-		    "mountflags: 0x%lx, mountopts: \"%s\"\n", dataset,
-		    mntpoint, mntflags, mntopts);
-
-	/* load the zfs posix layer module (zpl) */
-	if (libzfs_load_module("zpl")) {
-		(void) fprintf(stderr, gettext("filesystem '%s' cannot be "
-		    "mounted without the zpl kernel module\n"), dataset);
-		(void) fprintf(stderr, gettext("Use 'dmesg' to determine why "
-		    "the module could not be loaded.\n"));
-		return (MOUNT_SYSERR);
-	}
-
-	if (!fake) {
-		rc = mount(dataset, mntpoint, MNTTYPE_ZFS, mntflags, mntopts);
-		if (rc) {
-			(void) fprintf(stderr, gettext("filesystem '%s' can"
-			    "not be mounted due to error %d\n"), dataset, rc);
-			return (MOUNT_USAGE);
-		}
-	}
-
-	return (MOUNT_SUCCESS);
-}
-
-#ifdef HAVE_UNMOUNT_HELPER
-/*
- * Called when invoked as /sbin/umount.zfs, mount helper for mount(8).
- * Unlike a manual mount, we allow unmounts of non-legacy filesystems,
- * as this is the dominant administrative interface.
- */
-static int
-manual_unmount(int argc, char **argv)
-{
-	int verbose = 0, flags = 0;
-	int c;
-
-	/* check options */
-	while ((c = getopt(argc, argv, "nlfvrh?")) != -1) {
-		switch (c) {
-		case 'n':
-			/* Ignored, handled by mount(8) */
-			break;
-		case 'l':
-			flags = MS_DETACH;
-			break;
-		case 'f':
-			flags = MS_FORCE;
-			break;
-		case 'v':
-			verbose++;
-			break;
-		case 'r':
-			/* Remount read-only on umount failure, unsupported */
-			(void) fprintf(stderr, gettext("Unsupported option "
-			    "'%c'\n"), optopt);
-			return (MOUNT_USAGE);
-		case 'h':
-		case '?':
-			(void) fprintf(stderr, gettext("Invalid option '%c'\n"),
-			    optopt);
-			(void) fprintf(stderr, gettext("Usage: umount.zfs "
-			    "[-nlfvr] <mountpoint>\n"));
-			return (MOUNT_USAGE);
-		}
-	}
-
-	argc -= optind;
-	argv += optind;
-
-	/* check that we only have one argument */
-	if (argc != 1) {
-		if (argc == 0)
-			(void) fprintf(stderr, gettext("missing mountpoint "
-			    "argument\n"));
-		else
-			(void) fprintf(stderr, gettext("too many arguments\n"));
-
-		(void) fprintf(stderr, gettext("Usage: umount.zfs [-nlfvr] "
-		    "<mountpoint>\n"));
-		return (MOUNT_USAGE);
-	}
-
-	return (unshare_unmount_path(OP_MOUNT, argv[0], flags, B_TRUE));
-}
-#endif /* HAVE_UNMOUNT_HELPER */
-
 static int
 find_command_idx(char *command, int *idx)
 {
@@ -4289,7 +3924,6 @@ main(int argc, char **argv)
 {
 	int ret;
 	int i = 0;
-	char *progname;
 	char *cmdname;
 
 	(void) setlocale(LC_ALL, "");
@@ -4304,78 +3938,64 @@ main(int argc, char **argv)
 	}
 
 	/*
-	 * This command also doubles as the /etc/fs mount and unmount program.
-	 * Determine if we should take this behavior based on argv[0].
+	 * Make sure the user has specified some command.
 	 */
-	progname = basename(argv[0]);
-	if (strcmp(progname, "mount.zfs") == 0) {
-		ret = manual_mount(argc, argv);
-#ifdef HAVE_UNMOUNT_HELPER
-	} else if (strcmp(progname, "umount.zfs") == 0) {
-		ret = manual_unmount(argc, argv);
-#endif /* HAVE_UNMOUNT_HELPER */
-	} else {
-		/*
-		 * Make sure the user has specified some command.
-		 */
-		if (argc < 2) {
-			(void) fprintf(stderr, gettext("missing command\n"));
-			usage(B_FALSE);
-		}
+	if (argc < 2) {
+		(void) fprintf(stderr, gettext("missing command\n"));
+		usage(B_FALSE);
+	}
 
-		cmdname = argv[1];
+	cmdname = argv[1];
 
-		/*
-		 * The 'umount' command is an alias for 'unmount'
-		 */
-		if (strcmp(cmdname, "umount") == 0)
-			cmdname = "unmount";
+	/*
+	 * The 'umount' command is an alias for 'unmount'
+	 */
+	if (strcmp(cmdname, "umount") == 0)
+		cmdname = "unmount";
 
-		/*
-		 * The 'recv' command is an alias for 'receive'
-		 */
-		if (strcmp(cmdname, "recv") == 0)
-			cmdname = "receive";
+	/*
+	 * The 'recv' command is an alias for 'receive'
+	 */
+	if (strcmp(cmdname, "recv") == 0)
+		cmdname = "receive";
 
-		/*
-		 * Special case '-?'
-		 */
-		if ((strcmp(cmdname, "-?") == 0) ||
-		    (strcmp(cmdname, "--help") == 0))
-			usage(B_TRUE);
+	/*
+	 * Special case '-?'
+	 */
+	if ((strcmp(cmdname, "-?") == 0) ||
+	    (strcmp(cmdname, "--help") == 0))
+		usage(B_TRUE);
 
-		if ((g_zfs = libzfs_init()) == NULL)
-			return (1);
+	if ((g_zfs = libzfs_init()) == NULL)
+		return (1);
 
-		zpool_set_history_str("zfs", argc, argv, history_str);
-		verify(zpool_stage_history(g_zfs, history_str) == 0);
+	zpool_set_history_str("zfs", argc, argv, history_str);
+	verify(zpool_stage_history(g_zfs, history_str) == 0);
 
-		libzfs_print_on_error(g_zfs, B_TRUE);
+	libzfs_print_on_error(g_zfs, B_TRUE);
 
-		/*
-		 * Run the appropriate command.
-		 */
-		libzfs_mnttab_cache(g_zfs, B_TRUE);
-		if (find_command_idx(cmdname, &i) == 0) {
-			current_command = &command_table[i];
-			ret = command_table[i].func(argc - 1, argv + 1);
-		} else if (strchr(cmdname, '=') != NULL) {
-			verify(find_command_idx("set", &i) == 0);
-			current_command = &command_table[i];
-			ret = command_table[i].func(argc, argv);
-		} else {
-			(void) fprintf(stderr, gettext("unrecognized "
-			    "command '%s'\n"), cmdname);
-			usage(B_FALSE);
-			ret = 1;
-		}
-		libzfs_mnttab_cache(g_zfs, B_FALSE);
+	/*
+	 * Run the appropriate command.
+	 */
+	libzfs_mnttab_cache(g_zfs, B_TRUE);
+	if (find_command_idx(cmdname, &i) == 0) {
+		current_command = &command_table[i];
+		ret = command_table[i].func(argc - 1, argv + 1);
+	} else if (strchr(cmdname, '=') != NULL) {
+		verify(find_command_idx("set", &i) == 0);
+		current_command = &command_table[i];
+		ret = command_table[i].func(argc, argv);
+	} else {
+		(void) fprintf(stderr, gettext("unrecognized "
+		    "command '%s'\n"), cmdname);
+		usage(B_FALSE);
+		ret = 1;
 	}
+	libzfs_mnttab_cache(g_zfs, B_FALSE);
+	libzfs_fini(g_zfs);
 
 	(void) fclose(mnttab_file);
 
-	libzfs_fini(g_zfs);
-
 	/*
 	 * The 'ZFS_ABORT' environment variable causes us to dump core on exit
 	 * for the purposes of running ::findleaks.