Check remount options and return error if there is any unchangeable
option.
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
---
fs/overlayfs/super.c | 110 +++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 89 insertions(+), 21 deletions(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 5c8944b..ba00295 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -353,27 +353,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
return 0;
}
-static int ovl_remount(struct super_block *sb, int *flags, char *data)
-{
- struct ovl_fs *ofs = sb->s_fs_info;
-
- if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
- return -EROFS;
-
- return 0;
-}
-
-static const struct super_operations ovl_super_operations = {
- .alloc_inode = ovl_alloc_inode,
- .destroy_inode = ovl_destroy_inode,
- .drop_inode = generic_delete_inode,
- .put_super = ovl_put_super,
- .sync_fs = ovl_sync_fs,
- .statfs = ovl_statfs,
- .show_options = ovl_show_options,
- .remount_fs = ovl_remount,
-};
-
enum {
OPT_LOWERDIR,
OPT_UPPERDIR,
@@ -534,6 +513,95 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config, bool remount)
return ovl_parse_redirect_mode(config, config->redirect_mode);
}
+static bool ovl_string_option_equal(const char *new, const char *old)
+{
+ if (new) {
+ if (old) {
+ if (!strcmp(new, old))
+ return true;
+ else
+ return false;
+ } else {
+ return false;
+ }
+ } else {
+ if (old)
+ return false;
+ else
+ return true;
+ }
+}
+
+static int ovl_remount(struct super_block *sb, int *flags, char *data)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct ovl_config *old_config = &ofs->config;
+ struct ovl_config *new_config;
+ bool remount = true;
+ int err;
+
+ if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
+ return -EROFS;
+
+ new_config = kzalloc(sizeof(struct ovl_config), GFP_KERNEL);
+ if (!new_config)
+ return -ENOMEM;
+
+ new_config->index = old_config->index;
+ new_config->nfs_export = old_config->nfs_export;
+
+ err = ovl_parse_opt((char *)data, new_config, remount);
+ if (err)
+ goto out_err;
+
+ err = -EINVAL;
+ if (new_config->lowerdir &&
+ !ovl_string_option_equal(new_config->lowerdir,
+ old_config->lowerdir))
+ goto out_err;
+
+ if (new_config->upperdir &&
+ !ovl_string_option_equal(new_config->upperdir,
+ old_config->upperdir))
+ goto out_err;
+
+ if (new_config->workdir &&
+ !ovl_string_option_equal(new_config->workdir,
+ old_config->workdir))
+ goto out_err;
+
+ if (new_config->redirect_mode &&
+ !ovl_string_option_equal(new_config->redirect_mode,
+ old_config->redirect_mode))
+ goto out_err;
+
+ if (new_config->index != old_config->index)
+ goto out_err;
+
+ if (new_config->nfs_export != old_config->nfs_export)
+ goto out_err;
+
+ return 0;
+out_err:
+ kfree(new_config->lowerdir);
+ kfree(new_config->upperdir);
+ kfree(new_config->workdir);
+ kfree(new_config->redirect_mode);
+ kfree(new_config);
+ return err;
+}
+
+static const struct super_operations ovl_super_operations = {
+ .alloc_inode = ovl_alloc_inode,
+ .destroy_inode = ovl_destroy_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = ovl_put_super,
+ .sync_fs = ovl_sync_fs,
+ .statfs = ovl_statfs,
+ .show_options = ovl_show_options,
+ .remount_fs = ovl_remount,
+};
+
#define OVL_WORKDIR_NAME "work"
#define OVL_INDEXDIR_NAME "index"
--
1.8.3.1
--
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