![Linus Torvalds](/assets/img/avatar_default.png)
Pull mount flag updates from Al Viro: "Another chunk of fmount preparations from dhowells; only trivial conflicts for that part. It separates MS_... bits (very grotty mount(2) ABI) from the struct super_block ->s_flags (kernel-internal, only a small subset of MS_... stuff). This does *not* convert the filesystems to new constants; only the infrastructure is done here. The next step in that series is where the conflicts would be; that's the conversion of filesystems. It's purely mechanical and it's better done after the merge, so if you could run something like list=$(for i in MS_RDONLY MS_NOSUID MS_NODEV MS_NOEXEC MS_SYNCHRONOUS MS_MANDLOCK MS_DIRSYNC MS_NOATIME MS_NODIRATIME MS_SILENT MS_POSIXACL MS_KERNMOUNT MS_I_VERSION MS_LAZYTIME; do git grep -l $i fs drivers/staging/lustre drivers/mtd ipc mm include/linux; done|sort|uniq|grep -v '^fs/namespace.c$') sed -i -e 's/\<MS_RDONLY\>/SB_RDONLY/g' \ -e 's/\<MS_NOSUID\>/SB_NOSUID/g' \ -e 's/\<MS_NODEV\>/SB_NODEV/g' \ -e 's/\<MS_NOEXEC\>/SB_NOEXEC/g' \ -e 's/\<MS_SYNCHRONOUS\>/SB_SYNCHRONOUS/g' \ -e 's/\<MS_MANDLOCK\>/SB_MANDLOCK/g' \ -e 's/\<MS_DIRSYNC\>/SB_DIRSYNC/g' \ -e 's/\<MS_NOATIME\>/SB_NOATIME/g' \ -e 's/\<MS_NODIRATIME\>/SB_NODIRATIME/g' \ -e 's/\<MS_SILENT\>/SB_SILENT/g' \ -e 's/\<MS_POSIXACL\>/SB_POSIXACL/g' \ -e 's/\<MS_KERNMOUNT\>/SB_KERNMOUNT/g' \ -e 's/\<MS_I_VERSION\>/SB_I_VERSION/g' \ -e 's/\<MS_LAZYTIME\>/SB_LAZYTIME/g' \ $list and commit it with something along the lines of 'convert filesystems away from use of MS_... constants' as commit message, it would save a quite a bit of headache next cycle" * 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: VFS: Differentiate mount flags (MS_*) from internal superblock flags VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb) vfs: Add sb_rdonly(sb) to query the MS_RDONLY flag on s_flags
1230 lines
29 KiB
C
1230 lines
29 KiB
C
/*
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*
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* Copyright (C) 2011 Novell Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <uapi/linux/magic.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/xattr.h>
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#include <linux/mount.h>
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#include <linux/parser.h>
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#include <linux/module.h>
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#include <linux/statfs.h>
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#include <linux/seq_file.h>
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#include <linux/posix_acl_xattr.h>
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#include "overlayfs.h"
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#include "ovl_entry.h"
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MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
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MODULE_DESCRIPTION("Overlay filesystem");
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MODULE_LICENSE("GPL");
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struct ovl_dir_cache;
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#define OVL_MAX_STACK 500
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static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
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module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
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MODULE_PARM_DESC(ovl_redirect_dir_def,
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"Default to on or off for the redirect_dir feature");
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static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
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module_param_named(index, ovl_index_def, bool, 0644);
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MODULE_PARM_DESC(ovl_index_def,
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"Default to on or off for the inodes index feature");
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static void ovl_dentry_release(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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if (oe) {
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unsigned int i;
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for (i = 0; i < oe->numlower; i++)
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dput(oe->lowerstack[i].dentry);
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kfree_rcu(oe, rcu);
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}
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}
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static int ovl_check_append_only(struct inode *inode, int flag)
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{
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/*
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* This test was moot in vfs may_open() because overlay inode does
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* not have the S_APPEND flag, so re-check on real upper inode
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*/
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if (IS_APPEND(inode)) {
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if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
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return -EPERM;
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if (flag & O_TRUNC)
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return -EPERM;
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}
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return 0;
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}
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static struct dentry *ovl_d_real(struct dentry *dentry,
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const struct inode *inode,
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unsigned int open_flags, unsigned int flags)
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{
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struct dentry *real;
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int err;
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if (flags & D_REAL_UPPER)
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return ovl_dentry_upper(dentry);
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if (!d_is_reg(dentry)) {
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if (!inode || inode == d_inode(dentry))
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return dentry;
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goto bug;
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}
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if (open_flags) {
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err = ovl_open_maybe_copy_up(dentry, open_flags);
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if (err)
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return ERR_PTR(err);
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}
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real = ovl_dentry_upper(dentry);
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if (real && (!inode || inode == d_inode(real))) {
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if (!inode) {
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err = ovl_check_append_only(d_inode(real), open_flags);
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if (err)
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return ERR_PTR(err);
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}
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return real;
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}
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real = ovl_dentry_lower(dentry);
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if (!real)
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goto bug;
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/* Handle recursion */
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real = d_real(real, inode, open_flags, 0);
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if (!inode || inode == d_inode(real))
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return real;
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bug:
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WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
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inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
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return dentry;
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}
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static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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unsigned int i;
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int ret = 1;
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for (i = 0; i < oe->numlower; i++) {
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struct dentry *d = oe->lowerstack[i].dentry;
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if (d->d_flags & DCACHE_OP_REVALIDATE) {
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ret = d->d_op->d_revalidate(d, flags);
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if (ret < 0)
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return ret;
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if (!ret) {
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if (!(flags & LOOKUP_RCU))
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d_invalidate(d);
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return -ESTALE;
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}
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}
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}
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return 1;
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}
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static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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unsigned int i;
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int ret = 1;
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for (i = 0; i < oe->numlower; i++) {
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struct dentry *d = oe->lowerstack[i].dentry;
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if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
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ret = d->d_op->d_weak_revalidate(d, flags);
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if (ret <= 0)
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break;
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}
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}
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return ret;
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}
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static const struct dentry_operations ovl_dentry_operations = {
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.d_release = ovl_dentry_release,
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.d_real = ovl_d_real,
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};
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static const struct dentry_operations ovl_reval_dentry_operations = {
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.d_release = ovl_dentry_release,
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.d_real = ovl_d_real,
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.d_revalidate = ovl_dentry_revalidate,
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.d_weak_revalidate = ovl_dentry_weak_revalidate,
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};
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static struct kmem_cache *ovl_inode_cachep;
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static struct inode *ovl_alloc_inode(struct super_block *sb)
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{
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struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
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oi->cache = NULL;
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oi->redirect = NULL;
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oi->version = 0;
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oi->flags = 0;
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oi->__upperdentry = NULL;
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oi->lower = NULL;
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mutex_init(&oi->lock);
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return &oi->vfs_inode;
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}
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static void ovl_i_callback(struct rcu_head *head)
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{
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struct inode *inode = container_of(head, struct inode, i_rcu);
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kmem_cache_free(ovl_inode_cachep, OVL_I(inode));
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}
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static void ovl_destroy_inode(struct inode *inode)
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{
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struct ovl_inode *oi = OVL_I(inode);
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dput(oi->__upperdentry);
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kfree(oi->redirect);
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ovl_dir_cache_free(inode);
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mutex_destroy(&oi->lock);
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call_rcu(&inode->i_rcu, ovl_i_callback);
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}
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static void ovl_put_super(struct super_block *sb)
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{
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struct ovl_fs *ufs = sb->s_fs_info;
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unsigned i;
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dput(ufs->indexdir);
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dput(ufs->workdir);
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ovl_inuse_unlock(ufs->workbasedir);
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dput(ufs->workbasedir);
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if (ufs->upper_mnt)
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ovl_inuse_unlock(ufs->upper_mnt->mnt_root);
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mntput(ufs->upper_mnt);
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for (i = 0; i < ufs->numlower; i++)
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mntput(ufs->lower_mnt[i]);
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kfree(ufs->lower_mnt);
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kfree(ufs->config.lowerdir);
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kfree(ufs->config.upperdir);
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kfree(ufs->config.workdir);
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put_cred(ufs->creator_cred);
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kfree(ufs);
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}
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static int ovl_sync_fs(struct super_block *sb, int wait)
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{
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struct ovl_fs *ufs = sb->s_fs_info;
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struct super_block *upper_sb;
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int ret;
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if (!ufs->upper_mnt)
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return 0;
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upper_sb = ufs->upper_mnt->mnt_sb;
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if (!upper_sb->s_op->sync_fs)
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return 0;
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/* real inodes have already been synced by sync_filesystem(ovl_sb) */
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down_read(&upper_sb->s_umount);
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ret = upper_sb->s_op->sync_fs(upper_sb, wait);
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up_read(&upper_sb->s_umount);
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return ret;
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}
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/**
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* ovl_statfs
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* @sb: The overlayfs super block
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* @buf: The struct kstatfs to fill in with stats
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*
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* Get the filesystem statistics. As writes always target the upper layer
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* filesystem pass the statfs to the upper filesystem (if it exists)
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*/
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static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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struct dentry *root_dentry = dentry->d_sb->s_root;
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struct path path;
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int err;
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ovl_path_real(root_dentry, &path);
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err = vfs_statfs(&path, buf);
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if (!err) {
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buf->f_namelen = ofs->namelen;
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buf->f_type = OVERLAYFS_SUPER_MAGIC;
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}
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return err;
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}
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/* Will this overlay be forced to mount/remount ro? */
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static bool ovl_force_readonly(struct ovl_fs *ufs)
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{
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return (!ufs->upper_mnt || !ufs->workdir);
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}
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/**
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* ovl_show_options
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*
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* Prints the mount options for a given superblock.
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* Returns zero; does not fail.
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*/
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static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
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{
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struct super_block *sb = dentry->d_sb;
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struct ovl_fs *ufs = sb->s_fs_info;
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seq_show_option(m, "lowerdir", ufs->config.lowerdir);
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if (ufs->config.upperdir) {
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seq_show_option(m, "upperdir", ufs->config.upperdir);
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seq_show_option(m, "workdir", ufs->config.workdir);
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}
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if (ufs->config.default_permissions)
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seq_puts(m, ",default_permissions");
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if (ufs->config.redirect_dir != ovl_redirect_dir_def)
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seq_printf(m, ",redirect_dir=%s",
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ufs->config.redirect_dir ? "on" : "off");
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if (ufs->config.index != ovl_index_def)
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seq_printf(m, ",index=%s",
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ufs->config.index ? "on" : "off");
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return 0;
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}
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static int ovl_remount(struct super_block *sb, int *flags, char *data)
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{
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struct ovl_fs *ufs = sb->s_fs_info;
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if (!(*flags & MS_RDONLY) && ovl_force_readonly(ufs))
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return -EROFS;
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return 0;
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}
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static const struct super_operations ovl_super_operations = {
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.alloc_inode = ovl_alloc_inode,
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.destroy_inode = ovl_destroy_inode,
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.drop_inode = generic_delete_inode,
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.put_super = ovl_put_super,
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.sync_fs = ovl_sync_fs,
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.statfs = ovl_statfs,
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.show_options = ovl_show_options,
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.remount_fs = ovl_remount,
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};
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enum {
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OPT_LOWERDIR,
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OPT_UPPERDIR,
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OPT_WORKDIR,
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OPT_DEFAULT_PERMISSIONS,
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OPT_REDIRECT_DIR_ON,
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OPT_REDIRECT_DIR_OFF,
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OPT_INDEX_ON,
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OPT_INDEX_OFF,
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OPT_ERR,
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};
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static const match_table_t ovl_tokens = {
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{OPT_LOWERDIR, "lowerdir=%s"},
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{OPT_UPPERDIR, "upperdir=%s"},
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{OPT_WORKDIR, "workdir=%s"},
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{OPT_DEFAULT_PERMISSIONS, "default_permissions"},
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{OPT_REDIRECT_DIR_ON, "redirect_dir=on"},
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{OPT_REDIRECT_DIR_OFF, "redirect_dir=off"},
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{OPT_INDEX_ON, "index=on"},
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{OPT_INDEX_OFF, "index=off"},
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{OPT_ERR, NULL}
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};
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static char *ovl_next_opt(char **s)
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{
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char *sbegin = *s;
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char *p;
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if (sbegin == NULL)
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return NULL;
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for (p = sbegin; *p; p++) {
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if (*p == '\\') {
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p++;
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if (!*p)
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break;
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} else if (*p == ',') {
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*p = '\0';
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*s = p + 1;
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return sbegin;
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}
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}
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*s = NULL;
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return sbegin;
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}
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static int ovl_parse_opt(char *opt, struct ovl_config *config)
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{
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char *p;
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while ((p = ovl_next_opt(&opt)) != NULL) {
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int token;
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substring_t args[MAX_OPT_ARGS];
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if (!*p)
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continue;
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token = match_token(p, ovl_tokens, args);
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switch (token) {
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case OPT_UPPERDIR:
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kfree(config->upperdir);
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config->upperdir = match_strdup(&args[0]);
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if (!config->upperdir)
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return -ENOMEM;
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break;
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case OPT_LOWERDIR:
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kfree(config->lowerdir);
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config->lowerdir = match_strdup(&args[0]);
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if (!config->lowerdir)
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return -ENOMEM;
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break;
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case OPT_WORKDIR:
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kfree(config->workdir);
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config->workdir = match_strdup(&args[0]);
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if (!config->workdir)
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return -ENOMEM;
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break;
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case OPT_DEFAULT_PERMISSIONS:
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config->default_permissions = true;
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break;
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case OPT_REDIRECT_DIR_ON:
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config->redirect_dir = true;
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break;
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case OPT_REDIRECT_DIR_OFF:
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config->redirect_dir = false;
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break;
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case OPT_INDEX_ON:
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config->index = true;
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break;
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case OPT_INDEX_OFF:
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config->index = false;
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break;
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default:
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pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
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return -EINVAL;
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}
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}
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/* Workdir is useless in non-upper mount */
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if (!config->upperdir && config->workdir) {
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pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
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config->workdir);
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kfree(config->workdir);
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config->workdir = NULL;
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}
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return 0;
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}
|
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|
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#define OVL_WORKDIR_NAME "work"
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#define OVL_INDEXDIR_NAME "index"
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|
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static struct dentry *ovl_workdir_create(struct super_block *sb,
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struct ovl_fs *ufs,
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struct dentry *dentry,
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const char *name, bool persist)
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{
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struct inode *dir = dentry->d_inode;
|
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struct vfsmount *mnt = ufs->upper_mnt;
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struct dentry *work;
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int err;
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bool retried = false;
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bool locked = false;
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|
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err = mnt_want_write(mnt);
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if (err)
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goto out_err;
|
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|
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inode_lock_nested(dir, I_MUTEX_PARENT);
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locked = true;
|
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|
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retry:
|
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work = lookup_one_len(name, dentry, strlen(name));
|
|
|
|
if (!IS_ERR(work)) {
|
|
struct iattr attr = {
|
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.ia_valid = ATTR_MODE,
|
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.ia_mode = S_IFDIR | 0,
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};
|
|
|
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if (work->d_inode) {
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err = -EEXIST;
|
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if (retried)
|
|
goto out_dput;
|
|
|
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if (persist)
|
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goto out_unlock;
|
|
|
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retried = true;
|
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ovl_workdir_cleanup(dir, mnt, work, 0);
|
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dput(work);
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goto retry;
|
|
}
|
|
|
|
err = ovl_create_real(dir, work,
|
|
&(struct cattr){.mode = S_IFDIR | 0},
|
|
NULL, true);
|
|
if (err)
|
|
goto out_dput;
|
|
|
|
/*
|
|
* Try to remove POSIX ACL xattrs from workdir. We are good if:
|
|
*
|
|
* a) success (there was a POSIX ACL xattr and was removed)
|
|
* b) -ENODATA (there was no POSIX ACL xattr)
|
|
* c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
|
|
*
|
|
* There are various other error values that could effectively
|
|
* mean that the xattr doesn't exist (e.g. -ERANGE is returned
|
|
* if the xattr name is too long), but the set of filesystems
|
|
* allowed as upper are limited to "normal" ones, where checking
|
|
* for the above two errors is sufficient.
|
|
*/
|
|
err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
|
|
if (err && err != -ENODATA && err != -EOPNOTSUPP)
|
|
goto out_dput;
|
|
|
|
err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
|
|
if (err && err != -ENODATA && err != -EOPNOTSUPP)
|
|
goto out_dput;
|
|
|
|
/* Clear any inherited mode bits */
|
|
inode_lock(work->d_inode);
|
|
err = notify_change(work, &attr, NULL);
|
|
inode_unlock(work->d_inode);
|
|
if (err)
|
|
goto out_dput;
|
|
} else {
|
|
err = PTR_ERR(work);
|
|
goto out_err;
|
|
}
|
|
out_unlock:
|
|
mnt_drop_write(mnt);
|
|
if (locked)
|
|
inode_unlock(dir);
|
|
|
|
return work;
|
|
|
|
out_dput:
|
|
dput(work);
|
|
out_err:
|
|
pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
|
|
ufs->config.workdir, name, -err);
|
|
sb->s_flags |= MS_RDONLY;
|
|
work = NULL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
static void ovl_unescape(char *s)
|
|
{
|
|
char *d = s;
|
|
|
|
for (;; s++, d++) {
|
|
if (*s == '\\')
|
|
s++;
|
|
*d = *s;
|
|
if (!*s)
|
|
break;
|
|
}
|
|
}
|
|
|
|
static int ovl_mount_dir_noesc(const char *name, struct path *path)
|
|
{
|
|
int err = -EINVAL;
|
|
|
|
if (!*name) {
|
|
pr_err("overlayfs: empty lowerdir\n");
|
|
goto out;
|
|
}
|
|
err = kern_path(name, LOOKUP_FOLLOW, path);
|
|
if (err) {
|
|
pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
|
|
goto out;
|
|
}
|
|
err = -EINVAL;
|
|
if (ovl_dentry_weird(path->dentry)) {
|
|
pr_err("overlayfs: filesystem on '%s' not supported\n", name);
|
|
goto out_put;
|
|
}
|
|
if (!d_is_dir(path->dentry)) {
|
|
pr_err("overlayfs: '%s' not a directory\n", name);
|
|
goto out_put;
|
|
}
|
|
return 0;
|
|
|
|
out_put:
|
|
path_put(path);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_mount_dir(const char *name, struct path *path)
|
|
{
|
|
int err = -ENOMEM;
|
|
char *tmp = kstrdup(name, GFP_KERNEL);
|
|
|
|
if (tmp) {
|
|
ovl_unescape(tmp);
|
|
err = ovl_mount_dir_noesc(tmp, path);
|
|
|
|
if (!err)
|
|
if (ovl_dentry_remote(path->dentry)) {
|
|
pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
|
|
tmp);
|
|
path_put(path);
|
|
err = -EINVAL;
|
|
}
|
|
kfree(tmp);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
|
|
const char *name)
|
|
{
|
|
struct kstatfs statfs;
|
|
int err = vfs_statfs(path, &statfs);
|
|
|
|
if (err)
|
|
pr_err("overlayfs: statfs failed on '%s'\n", name);
|
|
else
|
|
ofs->namelen = max(ofs->namelen, statfs.f_namelen);
|
|
|
|
return err;
|
|
}
|
|
|
|
static int ovl_lower_dir(const char *name, struct path *path,
|
|
struct ovl_fs *ofs, int *stack_depth, bool *remote)
|
|
{
|
|
int err;
|
|
|
|
err = ovl_mount_dir_noesc(name, path);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = ovl_check_namelen(path, ofs, name);
|
|
if (err)
|
|
goto out_put;
|
|
|
|
*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
|
|
|
|
if (ovl_dentry_remote(path->dentry))
|
|
*remote = true;
|
|
|
|
/*
|
|
* The inodes index feature needs to encode and decode file
|
|
* handles, so it requires that all layers support them.
|
|
*/
|
|
if (ofs->config.index && !ovl_can_decode_fh(path->dentry->d_sb)) {
|
|
ofs->config.index = false;
|
|
pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off.\n", name);
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_put:
|
|
path_put(path);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/* Workdir should not be subdir of upperdir and vice versa */
|
|
static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
|
|
{
|
|
bool ok = false;
|
|
|
|
if (workdir != upperdir) {
|
|
ok = (lock_rename(workdir, upperdir) == NULL);
|
|
unlock_rename(workdir, upperdir);
|
|
}
|
|
return ok;
|
|
}
|
|
|
|
static unsigned int ovl_split_lowerdirs(char *str)
|
|
{
|
|
unsigned int ctr = 1;
|
|
char *s, *d;
|
|
|
|
for (s = d = str;; s++, d++) {
|
|
if (*s == '\\') {
|
|
s++;
|
|
} else if (*s == ':') {
|
|
*d = '\0';
|
|
ctr++;
|
|
continue;
|
|
}
|
|
*d = *s;
|
|
if (!*s)
|
|
break;
|
|
}
|
|
return ctr;
|
|
}
|
|
|
|
static int __maybe_unused
|
|
ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, void *buffer, size_t size)
|
|
{
|
|
return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
|
|
}
|
|
|
|
static int __maybe_unused
|
|
ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, const void *value,
|
|
size_t size, int flags)
|
|
{
|
|
struct dentry *workdir = ovl_workdir(dentry);
|
|
struct inode *realinode = ovl_inode_real(inode);
|
|
struct posix_acl *acl = NULL;
|
|
int err;
|
|
|
|
/* Check that everything is OK before copy-up */
|
|
if (value) {
|
|
acl = posix_acl_from_xattr(&init_user_ns, value, size);
|
|
if (IS_ERR(acl))
|
|
return PTR_ERR(acl);
|
|
}
|
|
err = -EOPNOTSUPP;
|
|
if (!IS_POSIXACL(d_inode(workdir)))
|
|
goto out_acl_release;
|
|
if (!realinode->i_op->set_acl)
|
|
goto out_acl_release;
|
|
if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
|
|
err = acl ? -EACCES : 0;
|
|
goto out_acl_release;
|
|
}
|
|
err = -EPERM;
|
|
if (!inode_owner_or_capable(inode))
|
|
goto out_acl_release;
|
|
|
|
posix_acl_release(acl);
|
|
|
|
/*
|
|
* Check if sgid bit needs to be cleared (actual setacl operation will
|
|
* be done with mounter's capabilities and so that won't do it for us).
|
|
*/
|
|
if (unlikely(inode->i_mode & S_ISGID) &&
|
|
handler->flags == ACL_TYPE_ACCESS &&
|
|
!in_group_p(inode->i_gid) &&
|
|
!capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
|
|
struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
|
|
|
|
err = ovl_setattr(dentry, &iattr);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
|
|
if (!err)
|
|
ovl_copyattr(ovl_inode_real(inode), inode);
|
|
|
|
return err;
|
|
|
|
out_acl_release:
|
|
posix_acl_release(acl);
|
|
return err;
|
|
}
|
|
|
|
static int ovl_own_xattr_get(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, void *buffer, size_t size)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static int ovl_own_xattr_set(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, const void *value,
|
|
size_t size, int flags)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static int ovl_other_xattr_get(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, void *buffer, size_t size)
|
|
{
|
|
return ovl_xattr_get(dentry, inode, name, buffer, size);
|
|
}
|
|
|
|
static int ovl_other_xattr_set(const struct xattr_handler *handler,
|
|
struct dentry *dentry, struct inode *inode,
|
|
const char *name, const void *value,
|
|
size_t size, int flags)
|
|
{
|
|
return ovl_xattr_set(dentry, inode, name, value, size, flags);
|
|
}
|
|
|
|
static const struct xattr_handler __maybe_unused
|
|
ovl_posix_acl_access_xattr_handler = {
|
|
.name = XATTR_NAME_POSIX_ACL_ACCESS,
|
|
.flags = ACL_TYPE_ACCESS,
|
|
.get = ovl_posix_acl_xattr_get,
|
|
.set = ovl_posix_acl_xattr_set,
|
|
};
|
|
|
|
static const struct xattr_handler __maybe_unused
|
|
ovl_posix_acl_default_xattr_handler = {
|
|
.name = XATTR_NAME_POSIX_ACL_DEFAULT,
|
|
.flags = ACL_TYPE_DEFAULT,
|
|
.get = ovl_posix_acl_xattr_get,
|
|
.set = ovl_posix_acl_xattr_set,
|
|
};
|
|
|
|
static const struct xattr_handler ovl_own_xattr_handler = {
|
|
.prefix = OVL_XATTR_PREFIX,
|
|
.get = ovl_own_xattr_get,
|
|
.set = ovl_own_xattr_set,
|
|
};
|
|
|
|
static const struct xattr_handler ovl_other_xattr_handler = {
|
|
.prefix = "", /* catch all */
|
|
.get = ovl_other_xattr_get,
|
|
.set = ovl_other_xattr_set,
|
|
};
|
|
|
|
static const struct xattr_handler *ovl_xattr_handlers[] = {
|
|
#ifdef CONFIG_FS_POSIX_ACL
|
|
&ovl_posix_acl_access_xattr_handler,
|
|
&ovl_posix_acl_default_xattr_handler,
|
|
#endif
|
|
&ovl_own_xattr_handler,
|
|
&ovl_other_xattr_handler,
|
|
NULL
|
|
};
|
|
|
|
static int ovl_fill_super(struct super_block *sb, void *data, int silent)
|
|
{
|
|
struct path upperpath = { };
|
|
struct path workpath = { };
|
|
struct dentry *root_dentry;
|
|
struct ovl_entry *oe;
|
|
struct ovl_fs *ufs;
|
|
struct path *stack = NULL;
|
|
char *lowertmp;
|
|
char *lower;
|
|
unsigned int numlower;
|
|
unsigned int stacklen = 0;
|
|
unsigned int i;
|
|
bool remote = false;
|
|
struct cred *cred;
|
|
int err;
|
|
|
|
err = -ENOMEM;
|
|
ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
|
|
if (!ufs)
|
|
goto out;
|
|
|
|
ufs->config.redirect_dir = ovl_redirect_dir_def;
|
|
ufs->config.index = ovl_index_def;
|
|
err = ovl_parse_opt((char *) data, &ufs->config);
|
|
if (err)
|
|
goto out_free_config;
|
|
|
|
err = -EINVAL;
|
|
if (!ufs->config.lowerdir) {
|
|
if (!silent)
|
|
pr_err("overlayfs: missing 'lowerdir'\n");
|
|
goto out_free_config;
|
|
}
|
|
|
|
sb->s_stack_depth = 0;
|
|
sb->s_maxbytes = MAX_LFS_FILESIZE;
|
|
if (ufs->config.upperdir) {
|
|
if (!ufs->config.workdir) {
|
|
pr_err("overlayfs: missing 'workdir'\n");
|
|
goto out_free_config;
|
|
}
|
|
|
|
err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
|
|
if (err)
|
|
goto out_free_config;
|
|
|
|
/* Upper fs should not be r/o */
|
|
if (sb_rdonly(upperpath.mnt->mnt_sb)) {
|
|
pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
|
|
err = -EINVAL;
|
|
goto out_put_upperpath;
|
|
}
|
|
|
|
err = ovl_check_namelen(&upperpath, ufs, ufs->config.upperdir);
|
|
if (err)
|
|
goto out_put_upperpath;
|
|
|
|
err = -EBUSY;
|
|
if (!ovl_inuse_trylock(upperpath.dentry)) {
|
|
pr_err("overlayfs: upperdir is in-use by another mount\n");
|
|
goto out_put_upperpath;
|
|
}
|
|
|
|
err = ovl_mount_dir(ufs->config.workdir, &workpath);
|
|
if (err)
|
|
goto out_unlock_upperdentry;
|
|
|
|
err = -EINVAL;
|
|
if (upperpath.mnt != workpath.mnt) {
|
|
pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
|
|
goto out_put_workpath;
|
|
}
|
|
if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
|
|
pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
|
|
goto out_put_workpath;
|
|
}
|
|
|
|
err = -EBUSY;
|
|
if (!ovl_inuse_trylock(workpath.dentry)) {
|
|
pr_err("overlayfs: workdir is in-use by another mount\n");
|
|
goto out_put_workpath;
|
|
}
|
|
|
|
ufs->workbasedir = workpath.dentry;
|
|
sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
|
|
}
|
|
err = -ENOMEM;
|
|
lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL);
|
|
if (!lowertmp)
|
|
goto out_unlock_workdentry;
|
|
|
|
err = -EINVAL;
|
|
stacklen = ovl_split_lowerdirs(lowertmp);
|
|
if (stacklen > OVL_MAX_STACK) {
|
|
pr_err("overlayfs: too many lower directories, limit is %d\n",
|
|
OVL_MAX_STACK);
|
|
goto out_free_lowertmp;
|
|
} else if (!ufs->config.upperdir && stacklen == 1) {
|
|
pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
|
|
goto out_free_lowertmp;
|
|
}
|
|
|
|
err = -ENOMEM;
|
|
stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
|
|
if (!stack)
|
|
goto out_free_lowertmp;
|
|
|
|
err = -EINVAL;
|
|
lower = lowertmp;
|
|
for (numlower = 0; numlower < stacklen; numlower++) {
|
|
err = ovl_lower_dir(lower, &stack[numlower], ufs,
|
|
&sb->s_stack_depth, &remote);
|
|
if (err)
|
|
goto out_put_lowerpath;
|
|
|
|
lower = strchr(lower, '\0') + 1;
|
|
}
|
|
|
|
err = -EINVAL;
|
|
sb->s_stack_depth++;
|
|
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
|
|
pr_err("overlayfs: maximum fs stacking depth exceeded\n");
|
|
goto out_put_lowerpath;
|
|
}
|
|
|
|
if (ufs->config.upperdir) {
|
|
ufs->upper_mnt = clone_private_mount(&upperpath);
|
|
err = PTR_ERR(ufs->upper_mnt);
|
|
if (IS_ERR(ufs->upper_mnt)) {
|
|
pr_err("overlayfs: failed to clone upperpath\n");
|
|
goto out_put_lowerpath;
|
|
}
|
|
|
|
/* Don't inherit atime flags */
|
|
ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
|
|
|
|
sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran;
|
|
|
|
ufs->workdir = ovl_workdir_create(sb, ufs, workpath.dentry,
|
|
OVL_WORKDIR_NAME, false);
|
|
/*
|
|
* Upper should support d_type, else whiteouts are visible.
|
|
* Given workdir and upper are on same fs, we can do
|
|
* iterate_dir() on workdir. This check requires successful
|
|
* creation of workdir in previous step.
|
|
*/
|
|
if (ufs->workdir) {
|
|
struct dentry *temp;
|
|
|
|
err = ovl_check_d_type_supported(&workpath);
|
|
if (err < 0)
|
|
goto out_put_workdir;
|
|
|
|
/*
|
|
* We allowed this configuration and don't want to
|
|
* break users over kernel upgrade. So warn instead
|
|
* of erroring out.
|
|
*/
|
|
if (!err)
|
|
pr_warn("overlayfs: upper fs needs to support d_type.\n");
|
|
|
|
/* Check if upper/work fs supports O_TMPFILE */
|
|
temp = ovl_do_tmpfile(ufs->workdir, S_IFREG | 0);
|
|
ufs->tmpfile = !IS_ERR(temp);
|
|
if (ufs->tmpfile)
|
|
dput(temp);
|
|
else
|
|
pr_warn("overlayfs: upper fs does not support tmpfile.\n");
|
|
|
|
/*
|
|
* Check if upper/work fs supports trusted.overlay.*
|
|
* xattr
|
|
*/
|
|
err = ovl_do_setxattr(ufs->workdir, OVL_XATTR_OPAQUE,
|
|
"0", 1, 0);
|
|
if (err) {
|
|
ufs->noxattr = true;
|
|
pr_warn("overlayfs: upper fs does not support xattr.\n");
|
|
} else {
|
|
vfs_removexattr(ufs->workdir, OVL_XATTR_OPAQUE);
|
|
}
|
|
|
|
/* Check if upper/work fs supports file handles */
|
|
if (ufs->config.index &&
|
|
!ovl_can_decode_fh(ufs->workdir->d_sb)) {
|
|
ufs->config.index = false;
|
|
pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
|
|
}
|
|
}
|
|
}
|
|
|
|
err = -ENOMEM;
|
|
ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
|
|
if (ufs->lower_mnt == NULL)
|
|
goto out_put_workdir;
|
|
for (i = 0; i < numlower; i++) {
|
|
struct vfsmount *mnt = clone_private_mount(&stack[i]);
|
|
|
|
err = PTR_ERR(mnt);
|
|
if (IS_ERR(mnt)) {
|
|
pr_err("overlayfs: failed to clone lowerpath\n");
|
|
goto out_put_lower_mnt;
|
|
}
|
|
/*
|
|
* Make lower_mnt R/O. That way fchmod/fchown on lower file
|
|
* will fail instead of modifying lower fs.
|
|
*/
|
|
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
|
|
|
|
ufs->lower_mnt[ufs->numlower] = mnt;
|
|
ufs->numlower++;
|
|
|
|
/* Check if all lower layers are on same sb */
|
|
if (i == 0)
|
|
ufs->same_sb = mnt->mnt_sb;
|
|
else if (ufs->same_sb != mnt->mnt_sb)
|
|
ufs->same_sb = NULL;
|
|
}
|
|
|
|
/* If the upper fs is nonexistent, we mark overlayfs r/o too */
|
|
if (!ufs->upper_mnt)
|
|
sb->s_flags |= MS_RDONLY;
|
|
else if (ufs->upper_mnt->mnt_sb != ufs->same_sb)
|
|
ufs->same_sb = NULL;
|
|
|
|
if (!(ovl_force_readonly(ufs)) && ufs->config.index) {
|
|
/* Verify lower root is upper root origin */
|
|
err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0],
|
|
stack[0].dentry, false, true);
|
|
if (err) {
|
|
pr_err("overlayfs: failed to verify upper root origin\n");
|
|
goto out_put_lower_mnt;
|
|
}
|
|
|
|
ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry,
|
|
OVL_INDEXDIR_NAME, true);
|
|
if (ufs->indexdir) {
|
|
/* Verify upper root is index dir origin */
|
|
err = ovl_verify_origin(ufs->indexdir, ufs->upper_mnt,
|
|
upperpath.dentry, true, true);
|
|
if (err)
|
|
pr_err("overlayfs: failed to verify index dir origin\n");
|
|
|
|
/* Cleanup bad/stale/orphan index entries */
|
|
if (!err)
|
|
err = ovl_indexdir_cleanup(ufs->indexdir,
|
|
ufs->upper_mnt,
|
|
stack, numlower);
|
|
}
|
|
if (err || !ufs->indexdir)
|
|
pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
|
|
if (err)
|
|
goto out_put_indexdir;
|
|
}
|
|
|
|
/* Show index=off/on in /proc/mounts for any of the reasons above */
|
|
if (!ufs->indexdir)
|
|
ufs->config.index = false;
|
|
|
|
if (remote)
|
|
sb->s_d_op = &ovl_reval_dentry_operations;
|
|
else
|
|
sb->s_d_op = &ovl_dentry_operations;
|
|
|
|
err = -ENOMEM;
|
|
ufs->creator_cred = cred = prepare_creds();
|
|
if (!cred)
|
|
goto out_put_indexdir;
|
|
|
|
/* Never override disk quota limits or use reserved space */
|
|
cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
|
|
|
|
err = -ENOMEM;
|
|
oe = ovl_alloc_entry(numlower);
|
|
if (!oe)
|
|
goto out_put_cred;
|
|
|
|
sb->s_magic = OVERLAYFS_SUPER_MAGIC;
|
|
sb->s_op = &ovl_super_operations;
|
|
sb->s_xattr = ovl_xattr_handlers;
|
|
sb->s_fs_info = ufs;
|
|
sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
|
|
|
|
root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
|
|
if (!root_dentry)
|
|
goto out_free_oe;
|
|
|
|
mntput(upperpath.mnt);
|
|
for (i = 0; i < numlower; i++)
|
|
mntput(stack[i].mnt);
|
|
mntput(workpath.mnt);
|
|
kfree(lowertmp);
|
|
|
|
if (upperpath.dentry) {
|
|
oe->has_upper = true;
|
|
if (ovl_is_impuredir(upperpath.dentry))
|
|
ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
|
|
}
|
|
for (i = 0; i < numlower; i++) {
|
|
oe->lowerstack[i].dentry = stack[i].dentry;
|
|
oe->lowerstack[i].mnt = ufs->lower_mnt[i];
|
|
}
|
|
kfree(stack);
|
|
|
|
root_dentry->d_fsdata = oe;
|
|
|
|
ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
|
|
ovl_dentry_lower(root_dentry));
|
|
|
|
sb->s_root = root_dentry;
|
|
|
|
return 0;
|
|
|
|
out_free_oe:
|
|
kfree(oe);
|
|
out_put_cred:
|
|
put_cred(ufs->creator_cred);
|
|
out_put_indexdir:
|
|
dput(ufs->indexdir);
|
|
out_put_lower_mnt:
|
|
for (i = 0; i < ufs->numlower; i++)
|
|
mntput(ufs->lower_mnt[i]);
|
|
kfree(ufs->lower_mnt);
|
|
out_put_workdir:
|
|
dput(ufs->workdir);
|
|
mntput(ufs->upper_mnt);
|
|
out_put_lowerpath:
|
|
for (i = 0; i < numlower; i++)
|
|
path_put(&stack[i]);
|
|
kfree(stack);
|
|
out_free_lowertmp:
|
|
kfree(lowertmp);
|
|
out_unlock_workdentry:
|
|
ovl_inuse_unlock(workpath.dentry);
|
|
out_put_workpath:
|
|
path_put(&workpath);
|
|
out_unlock_upperdentry:
|
|
ovl_inuse_unlock(upperpath.dentry);
|
|
out_put_upperpath:
|
|
path_put(&upperpath);
|
|
out_free_config:
|
|
kfree(ufs->config.lowerdir);
|
|
kfree(ufs->config.upperdir);
|
|
kfree(ufs->config.workdir);
|
|
kfree(ufs);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
|
|
const char *dev_name, void *raw_data)
|
|
{
|
|
return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
|
|
}
|
|
|
|
static struct file_system_type ovl_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "overlay",
|
|
.mount = ovl_mount,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
MODULE_ALIAS_FS("overlay");
|
|
|
|
static void ovl_inode_init_once(void *foo)
|
|
{
|
|
struct ovl_inode *oi = foo;
|
|
|
|
inode_init_once(&oi->vfs_inode);
|
|
}
|
|
|
|
static int __init ovl_init(void)
|
|
{
|
|
int err;
|
|
|
|
ovl_inode_cachep = kmem_cache_create("ovl_inode",
|
|
sizeof(struct ovl_inode), 0,
|
|
(SLAB_RECLAIM_ACCOUNT|
|
|
SLAB_MEM_SPREAD|SLAB_ACCOUNT),
|
|
ovl_inode_init_once);
|
|
if (ovl_inode_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
err = register_filesystem(&ovl_fs_type);
|
|
if (err)
|
|
kmem_cache_destroy(ovl_inode_cachep);
|
|
|
|
return err;
|
|
}
|
|
|
|
static void __exit ovl_exit(void)
|
|
{
|
|
unregister_filesystem(&ovl_fs_type);
|
|
|
|
/*
|
|
* Make sure all delayed rcu free inodes are flushed before we
|
|
* destroy cache.
|
|
*/
|
|
rcu_barrier();
|
|
kmem_cache_destroy(ovl_inode_cachep);
|
|
|
|
}
|
|
|
|
module_init(ovl_init);
|
|
module_exit(ovl_exit);
|