Fix mount permission issue

Signed-off-by: Umer Saleem <[email protected]>

contrib/initramfs/scripts/zfs

@@ -345,7 +345,7 @@ mount_fs()
 
 	# Need the _original_ datasets mountpoint!
 	mountpoint=$(get_fs_value "$fs" mountpoint)
-	ZFS_CMD="mount -o zfsutil -t zfs"
+	ZFS_CMD="mount.zfs -o zfsutil"
 	if [ "$mountpoint" = "legacy" ] || [ "$mountpoint" = "none" ]; then
 		# Can't use the mountpoint property. Might be one of our
 		# clones. Check the 'org.zol:mountpoint' property set in
@@ -362,7 +362,7 @@ mount_fs()
 			fi
 			# Don't use mount.zfs -o zfsutils for legacy mountpoint
 			if [ "$mountpoint" = "legacy" ]; then
-				ZFS_CMD="mount -t zfs"
+				ZFS_CMD="mount.zfs"
 			fi
 			# Last hail-mary: Hope 'rootmnt' is set!
 			mountpoint=""

module/os/linux/zfs/zfs_ctldir.c

@@ -1049,6 +1049,61 @@ exportfs_flush(void)
 	(void) call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
 }
 
+static int
+get_current_root_path(char *buff, int len)
+{
+	struct path path;
+	char *path_buffer, *path_ptr;
+	int path_len, error = 0;
+
+	get_fs_root(current->fs, &path);
+	path_get(&path);
+
+	path_buffer = kmem_zalloc(len, KM_SLEEP);
+
+	path_ptr = d_path(&path, path_buffer, len);
+	if (IS_ERR(path_ptr)) {
+		error = -PTR_ERR(path_ptr);
+		goto out;
+	}
+
+	path_len = path_buffer + len - 1 - path_ptr;
+	if (path_len > len) {
+		error = SET_ERROR(EFAULT);
+		goto out;
+	}
+
+	memcpy(buff, path_ptr, path_len);
+	buff[path_len] = '\0';
+out:
+	kmem_free(path_buffer, len);
+	path_put(&path);
+	return (error);
+}
+
+static int
+is_current_chrooted(void)
+{
+	struct task_struct *curr = current, *global = &init_task;
+	struct path gl_root;
+	struct path cr_root;
+	int chrooted;
+
+	get_fs_root(global->fs, &gl_root);
+	path_get(&gl_root);
+	while (d_mountpoint(gl_root.dentry) && follow_down_one(&gl_root))
+		;
+
+	get_fs_root(curr->fs, &cr_root);
+	path_get(&cr_root);
+	chrooted = !path_equal(&cr_root, &gl_root);
+
+	path_put(&cr_root);
+	path_put(&gl_root);
+
+	return (chrooted);
+}
+
 /*
  * Attempt to unmount a snapshot by making a call to user space.
  * There is no assurance that this can or will succeed, is just a
@@ -1100,7 +1155,7 @@ zfsctl_snapshot_mount(struct path *path, int flags)
 	zfsvfs_t *zfsvfs;
 	zfsvfs_t *snap_zfsvfs;
 	zfs_snapentry_t *se;
-	char *full_name, *full_path;
+	char *full_name, *full_path, *root_path;
 	char *argv[] = { "/usr/bin/env", "mount", "-i", "-t", "zfs", "-n",
 	    NULL, NULL, NULL };
 	char *envp[] = { NULL };
@@ -1116,12 +1171,30 @@ zfsctl_snapshot_mount(struct path *path, int flags)
 
 	full_name = kmem_zalloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP);
 	full_path = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
+	root_path = kmem_zalloc(MAXPATHLEN, KM_SLEEP);
 
 	error = zfsctl_snapshot_name(zfsvfs, dname(dentry),
 	    ZFS_MAX_DATASET_NAME_LEN, full_name);
 	if (error)
 		goto error;
 
+	if (get_current_root_path(root_path, MAXPATHLEN) == 0) {
+		if (is_current_chrooted() == 0) {
+			zfs_dbgmsg("current process is not chrooted");
+			if (zfsvfs->z_vfs->vfs_mntpoint != NULL &&
+			    strcmp(zfsvfs->z_vfs->vfs_mntpoint, "/root") == 0 &&
+			    strcmp(root_path, "/") == 0) {
+				zfs_dbgmsg("zfsvfs->z_vfs->vfs_mntpoint is /root");
+				zfs_dbgmsg("d_path returns / for current fs root");
+				zfs_dbgmsg("this is propbably root filesystem");
+				zfs_dbgmsg("setting zfsvfs->z_vfs->vfs_mntpoint to /");
+				strcpy(zfsvfs->z_vfs->vfs_mntpoint, "");
+			}
+		} else if (is_current_chrooted()) {
+			zfs_dbgmsg("Current process is in chroot context");
+		}
+	}
+
 	/*
 	 * Construct a mount point path from sb of the ctldir inode and dirent
 	 * name, instead of from d_path(), so that chroot'd process doesn't fail