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![Christian Brauner](/assets/img/avatar_default.png)
In earlier patches we already passed down the relevant upper or lower path to ovl_open_realfile(). Now let the open helpers actually take the idmapping of the relevant mount into account when checking permissions. This is needed to support idmapped base layers with overlay. Cc: <linux-unionfs@vger.kernel.org> Tested-by: Giuseppe Scrivano <gscrivan@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
1119 lines
27 KiB
C
1119 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2011 Novell Inc.
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* Copyright (C) 2016 Red Hat, Inc.
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*/
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/fileattr.h>
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#include <linux/uuid.h>
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#include <linux/namei.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.h"
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int ovl_want_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return mnt_want_write(ovl_upper_mnt(ofs));
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}
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void ovl_drop_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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mnt_drop_write(ovl_upper_mnt(ofs));
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}
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struct dentry *ovl_workdir(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return ofs->workdir;
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}
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const struct cred *ovl_override_creds(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return override_creds(ofs->creator_cred);
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}
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/*
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* Check if underlying fs supports file handles and try to determine encoding
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* type, in order to deduce maximum inode number used by fs.
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*
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* Return 0 if file handles are not supported.
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* Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
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* Return -1 if fs uses a non default encoding with unknown inode size.
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*/
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int ovl_can_decode_fh(struct super_block *sb)
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{
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if (!capable(CAP_DAC_READ_SEARCH))
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return 0;
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if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry)
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return 0;
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return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
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}
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struct dentry *ovl_indexdir(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->indexdir;
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}
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/* Index all files on copy up. For now only enabled for NFS export */
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bool ovl_index_all(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.nfs_export && ofs->config.index;
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}
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/* Verify lower origin on lookup. For now only enabled for NFS export */
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bool ovl_verify_lower(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.nfs_export && ofs->config.index;
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}
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struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
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{
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size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
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struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
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if (oe)
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oe->numlower = numlower;
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return oe;
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}
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bool ovl_dentry_remote(struct dentry *dentry)
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{
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return dentry->d_flags &
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(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
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}
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void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
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unsigned int mask)
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{
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struct ovl_entry *oe = OVL_E(dentry);
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unsigned int i, flags = 0;
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if (upperdentry)
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flags |= upperdentry->d_flags;
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for (i = 0; i < oe->numlower; i++)
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flags |= oe->lowerstack[i].dentry->d_flags;
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spin_lock(&dentry->d_lock);
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dentry->d_flags &= ~mask;
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dentry->d_flags |= flags & mask;
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spin_unlock(&dentry->d_lock);
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}
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bool ovl_dentry_weird(struct dentry *dentry)
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{
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return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
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DCACHE_MANAGE_TRANSIT |
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DCACHE_OP_HASH |
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DCACHE_OP_COMPARE);
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}
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enum ovl_path_type ovl_path_type(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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enum ovl_path_type type = 0;
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if (ovl_dentry_upper(dentry)) {
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type = __OVL_PATH_UPPER;
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/*
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* Non-dir dentry can hold lower dentry of its copy up origin.
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*/
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if (oe->numlower) {
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if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
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type |= __OVL_PATH_ORIGIN;
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if (d_is_dir(dentry) ||
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!ovl_has_upperdata(d_inode(dentry)))
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type |= __OVL_PATH_MERGE;
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}
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} else {
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if (oe->numlower > 1)
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type |= __OVL_PATH_MERGE;
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}
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return type;
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}
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void ovl_path_upper(struct dentry *dentry, struct path *path)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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path->mnt = ovl_upper_mnt(ofs);
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path->dentry = ovl_dentry_upper(dentry);
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}
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void ovl_path_lower(struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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if (oe->numlower) {
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path->mnt = oe->lowerstack[0].layer->mnt;
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path->dentry = oe->lowerstack[0].dentry;
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} else {
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*path = (struct path) { };
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}
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}
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void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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if (oe->numlower) {
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path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
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path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
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} else {
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*path = (struct path) { };
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}
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}
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enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
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{
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enum ovl_path_type type = ovl_path_type(dentry);
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if (!OVL_TYPE_UPPER(type))
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ovl_path_lower(dentry, path);
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else
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ovl_path_upper(dentry, path);
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return type;
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}
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enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
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{
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enum ovl_path_type type = ovl_path_type(dentry);
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WARN_ON_ONCE(d_is_dir(dentry));
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if (!OVL_TYPE_UPPER(type) || OVL_TYPE_MERGE(type))
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ovl_path_lowerdata(dentry, path);
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else
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ovl_path_upper(dentry, path);
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return type;
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}
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struct dentry *ovl_dentry_upper(struct dentry *dentry)
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{
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return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
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}
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struct dentry *ovl_dentry_lower(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[0].dentry : NULL;
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}
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const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[0].layer : NULL;
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}
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/*
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* ovl_dentry_lower() could return either a data dentry or metacopy dentry
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* depending on what is stored in lowerstack[0]. At times we need to find
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* lower dentry which has data (and not metacopy dentry). This helper
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* returns the lower data dentry.
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*/
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struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
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}
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struct dentry *ovl_dentry_real(struct dentry *dentry)
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{
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return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
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}
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struct dentry *ovl_i_dentry_upper(struct inode *inode)
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{
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return ovl_upperdentry_dereference(OVL_I(inode));
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}
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void ovl_i_path_real(struct inode *inode, struct path *path)
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{
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path->dentry = ovl_i_dentry_upper(inode);
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if (!path->dentry) {
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path->dentry = OVL_I(inode)->lowerpath.dentry;
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path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
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} else {
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path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
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}
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}
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struct inode *ovl_inode_upper(struct inode *inode)
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{
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struct dentry *upperdentry = ovl_i_dentry_upper(inode);
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return upperdentry ? d_inode(upperdentry) : NULL;
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}
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struct inode *ovl_inode_lower(struct inode *inode)
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{
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struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
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return lowerdentry ? d_inode(lowerdentry) : NULL;
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}
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struct inode *ovl_inode_real(struct inode *inode)
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{
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return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
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}
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/* Return inode which contains lower data. Do not return metacopy */
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struct inode *ovl_inode_lowerdata(struct inode *inode)
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{
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if (WARN_ON(!S_ISREG(inode->i_mode)))
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return NULL;
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return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
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}
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/* Return real inode which contains data. Does not return metacopy inode */
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struct inode *ovl_inode_realdata(struct inode *inode)
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{
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struct inode *upperinode;
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upperinode = ovl_inode_upper(inode);
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if (upperinode && ovl_has_upperdata(inode))
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return upperinode;
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return ovl_inode_lowerdata(inode);
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}
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struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
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{
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return OVL_I(inode)->cache;
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}
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void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
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{
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OVL_I(inode)->cache = cache;
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}
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void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
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{
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set_bit(flag, &OVL_E(dentry)->flags);
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}
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void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
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{
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clear_bit(flag, &OVL_E(dentry)->flags);
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}
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bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
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{
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return test_bit(flag, &OVL_E(dentry)->flags);
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}
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bool ovl_dentry_is_opaque(struct dentry *dentry)
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{
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return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
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}
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bool ovl_dentry_is_whiteout(struct dentry *dentry)
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{
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return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
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}
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void ovl_dentry_set_opaque(struct dentry *dentry)
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{
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ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
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}
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/*
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* For hard links and decoded file handles, it's possible for ovl_dentry_upper()
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* to return positive, while there's no actual upper alias for the inode.
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* Copy up code needs to know about the existence of the upper alias, so it
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* can't use ovl_dentry_upper().
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*/
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bool ovl_dentry_has_upper_alias(struct dentry *dentry)
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{
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return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
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}
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void ovl_dentry_set_upper_alias(struct dentry *dentry)
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{
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ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
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}
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static bool ovl_should_check_upperdata(struct inode *inode)
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{
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if (!S_ISREG(inode->i_mode))
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return false;
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if (!ovl_inode_lower(inode))
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return false;
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return true;
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}
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bool ovl_has_upperdata(struct inode *inode)
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{
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if (!ovl_should_check_upperdata(inode))
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return true;
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if (!ovl_test_flag(OVL_UPPERDATA, inode))
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return false;
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/*
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* Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
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* ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
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* if setting of OVL_UPPERDATA is visible, then effects of writes
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* before that are visible too.
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*/
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smp_rmb();
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return true;
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}
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void ovl_set_upperdata(struct inode *inode)
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{
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/*
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* Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
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* if OVL_UPPERDATA flag is visible, then effects of write operations
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* before it are visible as well.
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*/
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smp_wmb();
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ovl_set_flag(OVL_UPPERDATA, inode);
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}
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/* Caller should hold ovl_inode->lock */
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bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
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{
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if (!ovl_open_flags_need_copy_up(flags))
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return false;
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return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
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}
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bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
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{
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if (!ovl_open_flags_need_copy_up(flags))
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return false;
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return !ovl_has_upperdata(d_inode(dentry));
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}
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bool ovl_redirect_dir(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.redirect_dir && !ofs->noxattr;
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}
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const char *ovl_dentry_get_redirect(struct dentry *dentry)
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{
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return OVL_I(d_inode(dentry))->redirect;
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}
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void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
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{
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struct ovl_inode *oi = OVL_I(d_inode(dentry));
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kfree(oi->redirect);
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oi->redirect = redirect;
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}
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void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
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{
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struct inode *upperinode = d_inode(upperdentry);
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WARN_ON(OVL_I(inode)->__upperdentry);
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/*
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* Make sure upperdentry is consistent before making it visible
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*/
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smp_wmb();
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OVL_I(inode)->__upperdentry = upperdentry;
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if (inode_unhashed(inode)) {
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inode->i_private = upperinode;
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__insert_inode_hash(inode, (unsigned long) upperinode);
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}
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}
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static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
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{
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struct inode *inode = d_inode(dentry);
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WARN_ON(!inode_is_locked(inode));
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WARN_ON(!d_is_dir(dentry));
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/*
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* Version is used by readdir code to keep cache consistent.
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* For merge dirs (or dirs with origin) all changes need to be noted.
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* For non-merge dirs, cache contains only impure entries (i.e. ones
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* which have been copied up and have origins), so only need to note
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* changes to impure entries.
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*/
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if (!ovl_dir_is_real(dentry) || impurity)
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OVL_I(inode)->version++;
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}
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void ovl_dir_modified(struct dentry *dentry, bool impurity)
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{
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/* Copy mtime/ctime */
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ovl_copyattr(d_inode(dentry));
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ovl_dir_version_inc(dentry, impurity);
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}
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u64 ovl_dentry_version_get(struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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WARN_ON(!inode_is_locked(inode));
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return OVL_I(inode)->version;
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}
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bool ovl_is_whiteout(struct dentry *dentry)
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{
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struct inode *inode = dentry->d_inode;
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return inode && IS_WHITEOUT(inode);
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}
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struct file *ovl_path_open(struct path *path, int flags)
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{
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struct inode *inode = d_inode(path->dentry);
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struct user_namespace *real_mnt_userns = mnt_user_ns(path->mnt);
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int err, acc_mode;
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if (flags & ~(O_ACCMODE | O_LARGEFILE))
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BUG();
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switch (flags & O_ACCMODE) {
|
|
case O_RDONLY:
|
|
acc_mode = MAY_READ;
|
|
break;
|
|
case O_WRONLY:
|
|
acc_mode = MAY_WRITE;
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
err = inode_permission(real_mnt_userns, inode, acc_mode | MAY_OPEN);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
/* O_NOATIME is an optimization, don't fail if not permitted */
|
|
if (inode_owner_or_capable(real_mnt_userns, inode))
|
|
flags |= O_NOATIME;
|
|
|
|
return dentry_open(path, flags, current_cred());
|
|
}
|
|
|
|
/* Caller should hold ovl_inode->lock */
|
|
static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
|
|
{
|
|
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
|
|
|
|
if (ovl_dentry_upper(dentry) &&
|
|
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
|
|
!ovl_dentry_needs_data_copy_up_locked(dentry, flags))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool ovl_already_copied_up(struct dentry *dentry, int flags)
|
|
{
|
|
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
|
|
|
|
/*
|
|
* Check if copy-up has happened as well as for upper alias (in
|
|
* case of hard links) is there.
|
|
*
|
|
* Both checks are lockless:
|
|
* - false negatives: will recheck under oi->lock
|
|
* - false positives:
|
|
* + ovl_dentry_upper() uses memory barriers to ensure the
|
|
* upper dentry is up-to-date
|
|
* + ovl_dentry_has_upper_alias() relies on locking of
|
|
* upper parent i_rwsem to prevent reordering copy-up
|
|
* with rename.
|
|
*/
|
|
if (ovl_dentry_upper(dentry) &&
|
|
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
|
|
!ovl_dentry_needs_data_copy_up(dentry, flags))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
int ovl_copy_up_start(struct dentry *dentry, int flags)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
int err;
|
|
|
|
err = ovl_inode_lock_interruptible(inode);
|
|
if (!err && ovl_already_copied_up_locked(dentry, flags)) {
|
|
err = 1; /* Already copied up */
|
|
ovl_inode_unlock(inode);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_copy_up_end(struct dentry *dentry)
|
|
{
|
|
ovl_inode_unlock(d_inode(dentry));
|
|
}
|
|
|
|
bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, struct path *path)
|
|
{
|
|
int res;
|
|
|
|
res = ovl_path_getxattr(ofs, path, OVL_XATTR_ORIGIN, NULL, 0);
|
|
|
|
/* Zero size value means "copied up but origin unknown" */
|
|
if (res >= 0)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool ovl_path_check_dir_xattr(struct ovl_fs *ofs, struct path *path,
|
|
enum ovl_xattr ox)
|
|
{
|
|
int res;
|
|
char val;
|
|
|
|
if (!d_is_dir(path->dentry))
|
|
return false;
|
|
|
|
res = ovl_path_getxattr(ofs, path, ox, &val, 1);
|
|
if (res == 1 && val == 'y')
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
#define OVL_XATTR_OPAQUE_POSTFIX "opaque"
|
|
#define OVL_XATTR_REDIRECT_POSTFIX "redirect"
|
|
#define OVL_XATTR_ORIGIN_POSTFIX "origin"
|
|
#define OVL_XATTR_IMPURE_POSTFIX "impure"
|
|
#define OVL_XATTR_NLINK_POSTFIX "nlink"
|
|
#define OVL_XATTR_UPPER_POSTFIX "upper"
|
|
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
|
|
#define OVL_XATTR_PROTATTR_POSTFIX "protattr"
|
|
|
|
#define OVL_XATTR_TAB_ENTRY(x) \
|
|
[x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
|
|
[true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
|
|
|
|
const char *const ovl_xattr_table[][2] = {
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_PROTATTR),
|
|
};
|
|
|
|
int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
|
|
enum ovl_xattr ox, const void *value, size_t size,
|
|
int xerr)
|
|
{
|
|
int err;
|
|
|
|
if (ofs->noxattr)
|
|
return xerr;
|
|
|
|
err = ovl_setxattr(ofs, upperdentry, ox, value, size);
|
|
|
|
if (err == -EOPNOTSUPP) {
|
|
pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
|
|
ofs->noxattr = true;
|
|
return xerr;
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
|
|
int err;
|
|
|
|
if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
|
|
return 0;
|
|
|
|
/*
|
|
* Do not fail when upper doesn't support xattrs.
|
|
* Upper inodes won't have origin nor redirect xattr anyway.
|
|
*/
|
|
err = ovl_check_setxattr(ofs, upperdentry, OVL_XATTR_IMPURE, "y", 1, 0);
|
|
if (!err)
|
|
ovl_set_flag(OVL_IMPURE, d_inode(dentry));
|
|
|
|
return err;
|
|
}
|
|
|
|
|
|
#define OVL_PROTATTR_MAX 32 /* Reserved for future flags */
|
|
|
|
void ovl_check_protattr(struct inode *inode, struct dentry *upper)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(inode->i_sb);
|
|
u32 iflags = inode->i_flags & OVL_PROT_I_FLAGS_MASK;
|
|
char buf[OVL_PROTATTR_MAX+1];
|
|
int res, n;
|
|
|
|
res = ovl_getxattr_upper(ofs, upper, OVL_XATTR_PROTATTR, buf,
|
|
OVL_PROTATTR_MAX);
|
|
if (res < 0)
|
|
return;
|
|
|
|
/*
|
|
* Initialize inode flags from overlay.protattr xattr and upper inode
|
|
* flags. If upper inode has those fileattr flags set (i.e. from old
|
|
* kernel), we do not clear them on ovl_get_inode(), but we will clear
|
|
* them on next fileattr_set().
|
|
*/
|
|
for (n = 0; n < res; n++) {
|
|
if (buf[n] == 'a')
|
|
iflags |= S_APPEND;
|
|
else if (buf[n] == 'i')
|
|
iflags |= S_IMMUTABLE;
|
|
else
|
|
break;
|
|
}
|
|
|
|
if (!res || n < res) {
|
|
pr_warn_ratelimited("incompatible overlay.protattr format (%pd2, len=%d)\n",
|
|
upper, res);
|
|
} else {
|
|
inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
|
|
}
|
|
}
|
|
|
|
int ovl_set_protattr(struct inode *inode, struct dentry *upper,
|
|
struct fileattr *fa)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(inode->i_sb);
|
|
char buf[OVL_PROTATTR_MAX];
|
|
int len = 0, err = 0;
|
|
u32 iflags = 0;
|
|
|
|
BUILD_BUG_ON(HWEIGHT32(OVL_PROT_FS_FLAGS_MASK) > OVL_PROTATTR_MAX);
|
|
|
|
if (fa->flags & FS_APPEND_FL) {
|
|
buf[len++] = 'a';
|
|
iflags |= S_APPEND;
|
|
}
|
|
if (fa->flags & FS_IMMUTABLE_FL) {
|
|
buf[len++] = 'i';
|
|
iflags |= S_IMMUTABLE;
|
|
}
|
|
|
|
/*
|
|
* Do not allow to set protection flags when upper doesn't support
|
|
* xattrs, because we do not set those fileattr flags on upper inode.
|
|
* Remove xattr if it exist and all protection flags are cleared.
|
|
*/
|
|
if (len) {
|
|
err = ovl_check_setxattr(ofs, upper, OVL_XATTR_PROTATTR,
|
|
buf, len, -EPERM);
|
|
} else if (inode->i_flags & OVL_PROT_I_FLAGS_MASK) {
|
|
err = ovl_removexattr(ofs, upper, OVL_XATTR_PROTATTR);
|
|
if (err == -EOPNOTSUPP || err == -ENODATA)
|
|
err = 0;
|
|
}
|
|
if (err)
|
|
return err;
|
|
|
|
inode_set_flags(inode, iflags, OVL_PROT_I_FLAGS_MASK);
|
|
|
|
/* Mask out the fileattr flags that should not be set in upper inode */
|
|
fa->flags &= ~OVL_PROT_FS_FLAGS_MASK;
|
|
fa->fsx_xflags &= ~OVL_PROT_FSX_FLAGS_MASK;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Caller must hold a reference to inode to prevent it from being freed while
|
|
* it is marked inuse.
|
|
*/
|
|
bool ovl_inuse_trylock(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
bool locked = false;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
if (!(inode->i_state & I_OVL_INUSE)) {
|
|
inode->i_state |= I_OVL_INUSE;
|
|
locked = true;
|
|
}
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
return locked;
|
|
}
|
|
|
|
void ovl_inuse_unlock(struct dentry *dentry)
|
|
{
|
|
if (dentry) {
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
spin_lock(&inode->i_lock);
|
|
WARN_ON(!(inode->i_state & I_OVL_INUSE));
|
|
inode->i_state &= ~I_OVL_INUSE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
}
|
|
|
|
bool ovl_is_inuse(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
bool inuse;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
inuse = (inode->i_state & I_OVL_INUSE);
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
return inuse;
|
|
}
|
|
|
|
/*
|
|
* Does this overlay dentry need to be indexed on copy up?
|
|
*/
|
|
bool ovl_need_index(struct dentry *dentry)
|
|
{
|
|
struct dentry *lower = ovl_dentry_lower(dentry);
|
|
|
|
if (!lower || !ovl_indexdir(dentry->d_sb))
|
|
return false;
|
|
|
|
/* Index all files for NFS export and consistency verification */
|
|
if (ovl_index_all(dentry->d_sb))
|
|
return true;
|
|
|
|
/* Index only lower hardlinks on copy up */
|
|
if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* Caller must hold OVL_I(inode)->lock */
|
|
static void ovl_cleanup_index(struct dentry *dentry)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
|
|
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
|
|
struct inode *dir = indexdir->d_inode;
|
|
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
|
|
struct dentry *upperdentry = ovl_dentry_upper(dentry);
|
|
struct dentry *index = NULL;
|
|
struct inode *inode;
|
|
struct qstr name = { };
|
|
int err;
|
|
|
|
err = ovl_get_index_name(ofs, lowerdentry, &name);
|
|
if (err)
|
|
goto fail;
|
|
|
|
inode = d_inode(upperdentry);
|
|
if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
|
|
pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
|
|
upperdentry, inode->i_ino, inode->i_nlink);
|
|
/*
|
|
* We either have a bug with persistent union nlink or a lower
|
|
* hardlink was added while overlay is mounted. Adding a lower
|
|
* hardlink and then unlinking all overlay hardlinks would drop
|
|
* overlay nlink to zero before all upper inodes are unlinked.
|
|
* As a safety measure, when that situation is detected, set
|
|
* the overlay nlink to the index inode nlink minus one for the
|
|
* index entry itself.
|
|
*/
|
|
set_nlink(d_inode(dentry), inode->i_nlink - 1);
|
|
ovl_set_nlink_upper(dentry);
|
|
goto out;
|
|
}
|
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
|
|
err = PTR_ERR(index);
|
|
if (IS_ERR(index)) {
|
|
index = NULL;
|
|
} else if (ovl_index_all(dentry->d_sb)) {
|
|
/* Whiteout orphan index to block future open by handle */
|
|
err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
|
|
dir, index);
|
|
} else {
|
|
/* Cleanup orphan index entries */
|
|
err = ovl_cleanup(ofs, dir, index);
|
|
}
|
|
|
|
inode_unlock(dir);
|
|
if (err)
|
|
goto fail;
|
|
|
|
out:
|
|
kfree(name.name);
|
|
dput(index);
|
|
return;
|
|
|
|
fail:
|
|
pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Operations that change overlay inode and upper inode nlink need to be
|
|
* synchronized with copy up for persistent nlink accounting.
|
|
*/
|
|
int ovl_nlink_start(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
const struct cred *old_cred;
|
|
int err;
|
|
|
|
if (WARN_ON(!inode))
|
|
return -ENOENT;
|
|
|
|
/*
|
|
* With inodes index is enabled, we store the union overlay nlink
|
|
* in an xattr on the index inode. When whiting out an indexed lower,
|
|
* we need to decrement the overlay persistent nlink, but before the
|
|
* first copy up, we have no upper index inode to store the xattr.
|
|
*
|
|
* As a workaround, before whiteout/rename over an indexed lower,
|
|
* copy up to create the upper index. Creating the upper index will
|
|
* initialize the overlay nlink, so it could be dropped if unlink
|
|
* or rename succeeds.
|
|
*
|
|
* TODO: implement metadata only index copy up when called with
|
|
* ovl_copy_up_flags(dentry, O_PATH).
|
|
*/
|
|
if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
|
|
err = ovl_copy_up(dentry);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = ovl_inode_lock_interruptible(inode);
|
|
if (err)
|
|
return err;
|
|
|
|
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
|
|
goto out;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
/*
|
|
* The overlay inode nlink should be incremented/decremented IFF the
|
|
* upper operation succeeds, along with nlink change of upper inode.
|
|
* Therefore, before link/unlink/rename, we store the union nlink
|
|
* value relative to the upper inode nlink in an upper inode xattr.
|
|
*/
|
|
err = ovl_set_nlink_upper(dentry);
|
|
revert_creds(old_cred);
|
|
|
|
out:
|
|
if (err)
|
|
ovl_inode_unlock(inode);
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_nlink_end(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
|
|
const struct cred *old_cred;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
ovl_cleanup_index(dentry);
|
|
revert_creds(old_cred);
|
|
}
|
|
|
|
ovl_inode_unlock(inode);
|
|
}
|
|
|
|
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
|
|
{
|
|
/* Workdir should not be the same as upperdir */
|
|
if (workdir == upperdir)
|
|
goto err;
|
|
|
|
/* Workdir should not be subdir of upperdir and vice versa */
|
|
if (lock_rename(workdir, upperdir) != NULL)
|
|
goto err_unlock;
|
|
|
|
return 0;
|
|
|
|
err_unlock:
|
|
unlock_rename(workdir, upperdir);
|
|
err:
|
|
pr_err("failed to lock workdir+upperdir\n");
|
|
return -EIO;
|
|
}
|
|
|
|
/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
|
|
int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct path *path)
|
|
{
|
|
int res;
|
|
|
|
/* Only regular files can have metacopy xattr */
|
|
if (!S_ISREG(d_inode(path->dentry)->i_mode))
|
|
return 0;
|
|
|
|
res = ovl_path_getxattr(ofs, path, OVL_XATTR_METACOPY, NULL, 0);
|
|
if (res < 0) {
|
|
if (res == -ENODATA || res == -EOPNOTSUPP)
|
|
return 0;
|
|
/*
|
|
* getxattr on user.* may fail with EACCES in case there's no
|
|
* read permission on the inode. Not much we can do, other than
|
|
* tell the caller that this is not a metacopy inode.
|
|
*/
|
|
if (ofs->config.userxattr && res == -EACCES)
|
|
return 0;
|
|
goto out;
|
|
}
|
|
|
|
return 1;
|
|
out:
|
|
pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
|
|
return res;
|
|
}
|
|
|
|
bool ovl_is_metacopy_dentry(struct dentry *dentry)
|
|
{
|
|
struct ovl_entry *oe = dentry->d_fsdata;
|
|
|
|
if (!d_is_reg(dentry))
|
|
return false;
|
|
|
|
if (ovl_dentry_upper(dentry)) {
|
|
if (!ovl_has_upperdata(d_inode(dentry)))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
return (oe->numlower > 1);
|
|
}
|
|
|
|
char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct path *path, int padding)
|
|
{
|
|
int res;
|
|
char *s, *next, *buf = NULL;
|
|
|
|
res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, NULL, 0);
|
|
if (res == -ENODATA || res == -EOPNOTSUPP)
|
|
return NULL;
|
|
if (res < 0)
|
|
goto fail;
|
|
if (res == 0)
|
|
goto invalid;
|
|
|
|
buf = kzalloc(res + padding + 1, GFP_KERNEL);
|
|
if (!buf)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
res = ovl_path_getxattr(ofs, path, OVL_XATTR_REDIRECT, buf, res);
|
|
if (res < 0)
|
|
goto fail;
|
|
if (res == 0)
|
|
goto invalid;
|
|
|
|
if (buf[0] == '/') {
|
|
for (s = buf; *s++ == '/'; s = next) {
|
|
next = strchrnul(s, '/');
|
|
if (s == next)
|
|
goto invalid;
|
|
}
|
|
} else {
|
|
if (strchr(buf, '/') != NULL)
|
|
goto invalid;
|
|
}
|
|
|
|
return buf;
|
|
invalid:
|
|
pr_warn_ratelimited("invalid redirect (%s)\n", buf);
|
|
res = -EINVAL;
|
|
goto err_free;
|
|
fail:
|
|
pr_warn_ratelimited("failed to get redirect (%i)\n", res);
|
|
err_free:
|
|
kfree(buf);
|
|
return ERR_PTR(res);
|
|
}
|
|
|
|
/*
|
|
* ovl_sync_status() - Check fs sync status for volatile mounts
|
|
*
|
|
* Returns 1 if this is not a volatile mount and a real sync is required.
|
|
*
|
|
* Returns 0 if syncing can be skipped because mount is volatile, and no errors
|
|
* have occurred on the upperdir since the mount.
|
|
*
|
|
* Returns -errno if it is a volatile mount, and the error that occurred since
|
|
* the last mount. If the error code changes, it'll return the latest error
|
|
* code.
|
|
*/
|
|
|
|
int ovl_sync_status(struct ovl_fs *ofs)
|
|
{
|
|
struct vfsmount *mnt;
|
|
|
|
if (ovl_should_sync(ofs))
|
|
return 1;
|
|
|
|
mnt = ovl_upper_mnt(ofs);
|
|
if (!mnt)
|
|
return 0;
|
|
|
|
return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
|
|
}
|
|
|
|
/*
|
|
* ovl_copyattr() - copy inode attributes from layer to ovl inode
|
|
*
|
|
* When overlay copies inode information from an upper or lower layer to the
|
|
* relevant overlay inode it will apply the idmapping of the upper or lower
|
|
* layer when doing so ensuring that the ovl inode ownership will correctly
|
|
* reflect the ownership of the idmapped upper or lower layer. For example, an
|
|
* idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
|
|
* map any lower or upper inode owned by id 1001 to id 1000. These mapping
|
|
* helpers are nops when the relevant layer isn't idmapped.
|
|
*/
|
|
void ovl_copyattr(struct inode *inode)
|
|
{
|
|
struct path realpath;
|
|
struct inode *realinode;
|
|
struct user_namespace *real_mnt_userns;
|
|
|
|
ovl_i_path_real(inode, &realpath);
|
|
realinode = d_inode(realpath.dentry);
|
|
real_mnt_userns = mnt_user_ns(realpath.mnt);
|
|
|
|
inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);
|
|
inode->i_gid = i_gid_into_mnt(real_mnt_userns, realinode);
|
|
inode->i_mode = realinode->i_mode;
|
|
inode->i_atime = realinode->i_atime;
|
|
inode->i_mtime = realinode->i_mtime;
|
|
inode->i_ctime = realinode->i_ctime;
|
|
i_size_write(inode, i_size_read(realinode));
|
|
}
|