1 files changed, 355 insertions, 0 deletions
diff --git a/lib/libbe/be_access.c b/lib/libbe/be_access.c
new file mode 100644
index 000000000000..a7eb6b703cda
--- /dev/null
+++ b/lib/libbe/be_access.c
@@ -0,0 +1,355 @@
+/*
+ * Copyright (c) 2017 Kyle J. Kneitinger <kyle@kneit.in>
+ * Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org>
+ * Copyright (c) 2019 Wes Maag <wes@jwmaag.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/cdefs.h>
+#include <sys/mntent.h>
+
+#include "be.h"
+#include "be_impl.h"
+
+#define	LIBBE_MOUNT_PREFIX	"be_mount."
+
+struct be_mountcheck_info {
+	const char *path;
+	char *name;
+};
+
+struct be_mount_info {
+	libbe_handle_t *lbh;
+	const char *be;
+	const char *mountpoint;
+	int mntflags;
+	int deepmount;
+	int depth;
+};
+
+static int
+be_mountcheck_cb(zfs_handle_t *zfs_hdl, void *data)
+{
+	struct be_mountcheck_info *info;
+	char *mountpoint;
+
+	if (data == NULL)
+		return (1);
+	info = (struct be_mountcheck_info *)data;
+	if (!zfs_is_mounted(zfs_hdl, &mountpoint))
+		return (0);
+	if (strcmp(mountpoint, info->path) == 0) {
+		info->name = strdup(zfs_get_name(zfs_hdl));
+		free(mountpoint);
+		return (1);
+	}
+	free(mountpoint);
+	return (0);
+}
+
+/*
+ * Called from be_mount, uses the given zfs_handle and attempts to
+ * mount it at the passed mountpoint. If the deepmount flag is set, continue
+ * calling the function for each child dataset.
+ */
+static int
+be_mount_iter(zfs_handle_t *zfs_hdl, void *data)
+{
+	int err;
+	char *mountpoint;
+	char tmp[BE_MAXPATHLEN], zfs_mnt[BE_MAXPATHLEN];
+	struct be_mount_info *info;
+
+	info = (struct be_mount_info *)data;
+
+	if (zfs_is_mounted(zfs_hdl, &mountpoint)) {
+		free(mountpoint);
+		return (0);
+	}
+
+	/*
+	 * canmount and mountpoint are both ignored for the BE dataset, because
+	 * the rest of the system (kernel and loader) will effectively do the
+	 * same.
+	 */
+	if (info->depth == 0) {
+		snprintf(tmp, BE_MAXPATHLEN, "%s", info->mountpoint);
+	} else {
+		if (zfs_prop_get_int(zfs_hdl, ZFS_PROP_CANMOUNT) ==
+		    ZFS_CANMOUNT_OFF)
+			return (0);
+
+		if (zfs_prop_get(zfs_hdl, ZFS_PROP_MOUNTPOINT, zfs_mnt,
+		    BE_MAXPATHLEN, NULL, NULL, 0, 1))
+			return (1);
+
+		/*
+		 * We've encountered mountpoint=none at some intermediate
+		 * dataset (e.g. zroot/var) that will have children that may
+		 * need to be mounted.  Skip mounting it, but iterate through
+		 * the children.
+		 */
+		if (strcmp("none", zfs_mnt) == 0)
+			goto skipmount;
+
+		mountpoint = be_mountpoint_augmented(info->lbh, zfs_mnt);
+		snprintf(tmp, BE_MAXPATHLEN, "%s%s", info->mountpoint,
+		    mountpoint);
+	}
+
+	if ((err = zfs_mount_at(zfs_hdl, NULL, info->mntflags, tmp)) != 0) {
+		switch (errno) {
+		case ENAMETOOLONG:
+			return (set_error(info->lbh, BE_ERR_PATHLEN));
+		case ELOOP:
+		case ENOENT:
+		case ENOTDIR:
+			return (set_error(info->lbh, BE_ERR_BADPATH));
+		case EPERM:
+			return (set_error(info->lbh, BE_ERR_PERMS));
+		case EBUSY:
+			return (set_error(info->lbh, BE_ERR_PATHBUSY));
+		default:
+			return (set_error(info->lbh, BE_ERR_UNKNOWN));
+		}
+	}
+
+	if (!info->deepmount)
+		return (0);
+
+skipmount:
+	++info->depth;
+	err = zfs_iter_filesystems(zfs_hdl, be_mount_iter, info);
+	--info->depth;
+	return (err);
+}
+
+
+static int
+be_umount_iter(zfs_handle_t *zfs_hdl, void *data)
+{
+
+	int err;
+	char *mountpoint;
+	struct be_mount_info *info;
+
+	info = (struct be_mount_info *)data;
+
+	++info->depth;
+	if((err = zfs_iter_filesystems(zfs_hdl, be_umount_iter, info)) != 0) {
+		return (err);
+	}
+	--info->depth;
+
+	if (!zfs_is_mounted(zfs_hdl, &mountpoint)) {
+		return (0);
+	}
+
+	if (info->depth == 0 && info->mountpoint == NULL)
+		info->mountpoint = mountpoint;
+	else
+		free(mountpoint);
+
+	if (zfs_unmount(zfs_hdl, NULL, info->mntflags) != 0) {
+		switch (errno) {
+		case ENAMETOOLONG:
+			return (set_error(info->lbh, BE_ERR_PATHLEN));
+		case ELOOP:
+		case ENOENT:
+		case ENOTDIR:
+			return (set_error(info->lbh, BE_ERR_BADPATH));
+		case EPERM:
+			return (set_error(info->lbh, BE_ERR_PERMS));
+		case EBUSY:
+			return (set_error(info->lbh, BE_ERR_PATHBUSY));
+		default:
+			return (set_error(info->lbh, BE_ERR_UNKNOWN));
+		}
+	}
+	return (0);
+}
+
+/*
+ * usage
+ */
+int
+be_mounted_at(libbe_handle_t *lbh, const char *path, nvlist_t *details)
+{
+	char be[BE_MAXPATHLEN];
+	zfs_handle_t *root_hdl;
+	struct be_mountcheck_info info;
+	prop_data_t propinfo;
+
+	bzero(&be, BE_MAXPATHLEN);
+	if ((root_hdl = zfs_open(lbh->lzh, lbh->root,
+	    ZFS_TYPE_FILESYSTEM)) == NULL)
+		return (BE_ERR_ZFSOPEN);
+
+	info.path = path;
+	info.name = NULL;
+	zfs_iter_filesystems(root_hdl, be_mountcheck_cb, &info);
+	zfs_close(root_hdl);
+
+	if (info.name != NULL) {
+		if (details != NULL) {
+			if ((root_hdl = zfs_open(lbh->lzh, info.name,
+			    ZFS_TYPE_FILESYSTEM)) == NULL) {
+				free(info.name);
+				return (BE_ERR_ZFSOPEN);
+			}
+
+			propinfo.lbh = lbh;
+			propinfo.list = details;
+			propinfo.single_object = false;
+			propinfo.bootonce = NULL;
+			prop_list_builder_cb(root_hdl, &propinfo);
+			zfs_close(root_hdl);
+		}
+		free(info.name);
+		return (0);
+	}
+	return (1);
+}
+
+/*
+ * usage
+ */
+int
+be_mount(libbe_handle_t *lbh, const char *bootenv, const char *mountpoint,
+    int flags, char *result_loc)
+{
+	char be[BE_MAXPATHLEN];
+	char mnt_temp[BE_MAXPATHLEN];
+	int mntflags, mntdeep;
+	int err;
+	struct be_mount_info info;
+	zfs_handle_t *zhdl;
+
+	if ((err = be_root_concat(lbh, bootenv, be)) != 0)
+		return (set_error(lbh, err));
+
+	if ((err = be_exists(lbh, bootenv)) != 0)
+		return (set_error(lbh, err));
+
+	if (is_mounted(lbh->lzh, be, NULL))
+		return (set_error(lbh, BE_ERR_MOUNTED));
+
+	mntdeep = (flags & BE_MNT_DEEP) ? 1 : 0;
+	mntflags = (flags & BE_MNT_FORCE) ? MNT_FORCE : 0;
+
+	/* Create mountpoint if it is not specified */
+	if (mountpoint == NULL) {
+		const char *tmpdir;
+
+		tmpdir = getenv("TMPDIR");
+		if (tmpdir == NULL)
+			tmpdir = _PATH_TMP;
+
+		if (snprintf(mnt_temp, sizeof(mnt_temp), "%s%s%sXXXX", tmpdir,
+		    tmpdir[strlen(tmpdir) - 1] == '/' ? "" : "/",
+		     LIBBE_MOUNT_PREFIX) >= (int)sizeof(mnt_temp))
+			return (set_error(lbh, BE_ERR_PATHLEN));
+
+		if (mkdtemp(mnt_temp) == NULL)
+			return (set_error(lbh, BE_ERR_IO));
+	}
+
+	if ((zhdl = zfs_open(lbh->lzh, be, ZFS_TYPE_FILESYSTEM)) == NULL)
+		return (set_error(lbh, BE_ERR_ZFSOPEN));
+
+	info.lbh = lbh;
+	info.be = be;
+	info.mountpoint = (mountpoint == NULL) ? mnt_temp : mountpoint;
+	info.mntflags = mntflags;
+	info.deepmount = mntdeep;
+	info.depth = 0;
+
+	if((err = be_mount_iter(zhdl, &info) != 0)) {
+		zfs_close(zhdl);
+		return (err);
+	}
+	zfs_close(zhdl);
+
+	if (result_loc != NULL)
+		strlcpy(result_loc, mountpoint == NULL ? mnt_temp : mountpoint,
+		    BE_MAXPATHLEN);
+
+	return (BE_ERR_SUCCESS);
+}
+
+/*
+ * usage
+ */
+int
+be_unmount(libbe_handle_t *lbh, const char *bootenv, int flags)
+{
+	int err;
+	char be[BE_MAXPATHLEN];
+	zfs_handle_t *root_hdl;
+	struct be_mount_info info;
+
+	if ((err = be_root_concat(lbh, bootenv, be)) != 0)
+		return (set_error(lbh, err));
+
+	if ((root_hdl = zfs_open(lbh->lzh, be, ZFS_TYPE_FILESYSTEM)) == NULL)
+		return (set_error(lbh, BE_ERR_ZFSOPEN));
+
+	info.lbh = lbh;
+	info.be = be;
+	info.mountpoint = NULL;
+	info.mntflags = (flags & BE_MNT_FORCE) ? MS_FORCE : 0;
+	info.depth = 0;
+
+	if ((err = be_umount_iter(root_hdl, &info)) != 0) {
+		free(__DECONST(char *, info.mountpoint));
+		zfs_close(root_hdl);
+		return (err);
+	}
+
+	/*
+	 * We'll attempt to remove the directory if we created it on a
+	 * best-effort basis.  rmdir(2) failure will not be reported.
+	 */
+	if (info.mountpoint != NULL) {
+		const char *mdir;
+
+		mdir = strrchr(info.mountpoint, '/');
+		if (mdir == NULL)
+			mdir = info.mountpoint;
+		else
+			mdir++;
+
+		if (strncmp(mdir, LIBBE_MOUNT_PREFIX,
+		    sizeof(LIBBE_MOUNT_PREFIX) - 1) == 0) {
+			(void)rmdir(info.mountpoint);
+		}
+	}
+
+	free(__DECONST(char *, info.mountpoint));
+
+	zfs_close(root_hdl);
+	return (BE_ERR_SUCCESS);
+}
+
+/*
+ * This function will blow away the input buffer as needed if we're discovered
+ * to be looking at a root-mount.  If the mountpoint is naturally beyond the
+ * root, however, the buffer may be left intact and a pointer to the section
+ * past altroot will be returned instead for the caller's perusal.
+ */
+char *
+be_mountpoint_augmented(libbe_handle_t *lbh, char *mountpoint)
+{
+
+	if (lbh->altroot_len == 0)
+		return (mountpoint);
+	if (mountpoint == NULL || *mountpoint == '\0')
+		return (mountpoint);
+
+	if (mountpoint[lbh->altroot_len] == '\0') {
+		*(mountpoint + 1) = '\0';
+		return (mountpoint);
+	} else
+		return (mountpoint + lbh->altroot_len);
+}