From 48bd024b8a40d73ad6b086de2615738da0c7004f Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 2 Jun 2020 22:20:25 +0200 Subject: ovl: switch to mounter creds in readdir In preparation for more permission checking, override credentials for directory operations on the underlying filesystems. Signed-off-by: Miklos Szeredi --- fs/overlayfs/readdir.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) Index: linux-5.4.147/fs/overlayfs/readdir.c =================================================================== --- linux-5.4.147.orig/fs/overlayfs/readdir.c +++ linux-5.4.147/fs/overlayfs/readdir.c @@ -732,8 +732,10 @@ static int ovl_iterate(struct file *file struct ovl_dir_file *od = file->private_data; struct dentry *dentry = file->f_path.dentry; struct ovl_cache_entry *p; + const struct cred *old_cred; int err; + old_cred = ovl_override_creds(dentry->d_sb); if (!ctx->pos) ovl_dir_reset(file); @@ -747,17 +749,20 @@ static int ovl_iterate(struct file *file (ovl_same_sb(dentry->d_sb) && (ovl_is_impure_dir(file) || OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) { - return ovl_iterate_real(file, ctx); + err = ovl_iterate_real(file, ctx); + } else { + err = iterate_dir(od->realfile, ctx); } - return iterate_dir(od->realfile, ctx); + goto out; } if (!od->cache) { struct ovl_dir_cache *cache; cache = ovl_cache_get(dentry); + err = PTR_ERR(cache); if (IS_ERR(cache)) - return PTR_ERR(cache); + goto out; od->cache = cache; ovl_seek_cursor(od, ctx->pos); @@ -769,7 +774,7 @@ static int ovl_iterate(struct file *file if (!p->ino) { err = ovl_cache_update_ino(&file->f_path, p); if (err) - return err; + goto out; } if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) break; @@ -777,7 +782,10 @@ static int ovl_iterate(struct file *file od->cursor = p->l_node.next; ctx->pos++; } - return 0; + err = 0; +out: + revert_creds(old_cred); + return err; } static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)