![Miklos Szeredi](/assets/img/avatar_default.png)
Make permission checking more consistent: - special files don't need any access check on underling fs - exec permission check doesn't need to be performed on underlying fs Reported-by: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
932 lines
24 KiB
C
932 lines
24 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 <linux/fs.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/posix_acl.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.h"
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int ovl_setattr(struct dentry *dentry, struct iattr *attr)
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{
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int err;
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bool full_copy_up = false;
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struct dentry *upperdentry;
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const struct cred *old_cred;
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err = setattr_prepare(dentry, attr);
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if (err)
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return err;
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err = ovl_want_write(dentry);
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if (err)
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goto out;
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if (attr->ia_valid & ATTR_SIZE) {
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struct inode *realinode = d_inode(ovl_dentry_real(dentry));
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err = -ETXTBSY;
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if (atomic_read(&realinode->i_writecount) < 0)
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goto out_drop_write;
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/* Truncate should trigger data copy up as well */
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full_copy_up = true;
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}
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if (!full_copy_up)
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err = ovl_copy_up(dentry);
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else
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err = ovl_copy_up_with_data(dentry);
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if (!err) {
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struct inode *winode = NULL;
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upperdentry = ovl_dentry_upper(dentry);
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if (attr->ia_valid & ATTR_SIZE) {
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winode = d_inode(upperdentry);
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err = get_write_access(winode);
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if (err)
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goto out_drop_write;
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}
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if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
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attr->ia_valid &= ~ATTR_MODE;
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inode_lock(upperdentry->d_inode);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = notify_change(upperdentry, attr, NULL);
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revert_creds(old_cred);
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if (!err)
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ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
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inode_unlock(upperdentry->d_inode);
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if (winode)
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put_write_access(winode);
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}
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out_drop_write:
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ovl_drop_write(dentry);
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out:
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return err;
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}
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static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
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struct ovl_layer *lower_layer)
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{
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bool samefs = ovl_same_sb(dentry->d_sb);
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unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
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if (samefs) {
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/*
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* When all layers are on the same fs, all real inode
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* number are unique, so we use the overlay st_dev,
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* which is friendly to du -x.
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*/
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stat->dev = dentry->d_sb->s_dev;
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return 0;
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} else if (xinobits) {
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unsigned int shift = 64 - xinobits;
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/*
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* All inode numbers of underlying fs should not be using the
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* high xinobits, so we use high xinobits to partition the
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* overlay st_ino address space. The high bits holds the fsid
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* (upper fsid is 0). This way overlay inode numbers are unique
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* and all inodes use overlay st_dev. Inode numbers are also
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* persistent for a given layer configuration.
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*/
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if (stat->ino >> shift) {
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pr_warn_ratelimited("overlayfs: inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
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dentry, stat->ino, xinobits);
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} else {
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if (lower_layer)
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stat->ino |= ((u64)lower_layer->fsid) << shift;
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stat->dev = dentry->d_sb->s_dev;
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return 0;
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}
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}
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/* The inode could not be mapped to a unified st_ino address space */
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if (S_ISDIR(dentry->d_inode->i_mode)) {
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/*
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* Always use the overlay st_dev for directories, so 'find
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* -xdev' will scan the entire overlay mount and won't cross the
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* overlay mount boundaries.
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*
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* If not all layers are on the same fs the pair {real st_ino;
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* overlay st_dev} is not unique, so use the non persistent
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* overlay st_ino for directories.
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*/
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stat->dev = dentry->d_sb->s_dev;
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stat->ino = dentry->d_inode->i_ino;
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} else if (lower_layer && lower_layer->fsid) {
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/*
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* For non-samefs setup, if we cannot map all layers st_ino
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* to a unified address space, we need to make sure that st_dev
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* is unique per lower fs. Upper layer uses real st_dev and
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* lower layers use the unique anonymous bdev assigned to the
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* lower fs.
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*/
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stat->dev = lower_layer->fs->pseudo_dev;
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}
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return 0;
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}
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int ovl_getattr(const struct path *path, struct kstat *stat,
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u32 request_mask, unsigned int flags)
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{
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struct dentry *dentry = path->dentry;
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enum ovl_path_type type;
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struct path realpath;
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const struct cred *old_cred;
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bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
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bool samefs = ovl_same_sb(dentry->d_sb);
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struct ovl_layer *lower_layer = NULL;
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int err;
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bool metacopy_blocks = false;
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metacopy_blocks = ovl_is_metacopy_dentry(dentry);
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type = ovl_path_real(dentry, &realpath);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = vfs_getattr(&realpath, stat, request_mask, flags);
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if (err)
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goto out;
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/*
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* For non-dir or same fs, we use st_ino of the copy up origin.
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* This guaranties constant st_dev/st_ino across copy up.
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* With xino feature and non-samefs, we use st_ino of the copy up
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* origin masked with high bits that represent the layer id.
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*
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* If lower filesystem supports NFS file handles, this also guaranties
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* persistent st_ino across mount cycle.
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*/
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if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
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if (!OVL_TYPE_UPPER(type)) {
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lower_layer = ovl_layer_lower(dentry);
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} else if (OVL_TYPE_ORIGIN(type)) {
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struct kstat lowerstat;
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u32 lowermask = STATX_INO | STATX_BLOCKS |
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(!is_dir ? STATX_NLINK : 0);
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ovl_path_lower(dentry, &realpath);
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err = vfs_getattr(&realpath, &lowerstat,
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lowermask, flags);
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if (err)
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goto out;
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/*
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* Lower hardlinks may be broken on copy up to different
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* upper files, so we cannot use the lower origin st_ino
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* for those different files, even for the same fs case.
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*
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* Similarly, several redirected dirs can point to the
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* same dir on a lower layer. With the "verify_lower"
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* feature, we do not use the lower origin st_ino, if
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* we haven't verified that this redirect is unique.
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*
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* With inodes index enabled, it is safe to use st_ino
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* of an indexed origin. The index validates that the
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* upper hardlink is not broken and that a redirected
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* dir is the only redirect to that origin.
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*/
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if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
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(!ovl_verify_lower(dentry->d_sb) &&
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(is_dir || lowerstat.nlink == 1))) {
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stat->ino = lowerstat.ino;
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lower_layer = ovl_layer_lower(dentry);
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}
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/*
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* If we are querying a metacopy dentry and lower
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* dentry is data dentry, then use the blocks we
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* queried just now. We don't have to do additional
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* vfs_getattr(). If lower itself is metacopy, then
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* additional vfs_getattr() is unavoidable.
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*/
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if (metacopy_blocks &&
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realpath.dentry == ovl_dentry_lowerdata(dentry)) {
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stat->blocks = lowerstat.blocks;
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metacopy_blocks = false;
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}
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}
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if (metacopy_blocks) {
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/*
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* If lower is not same as lowerdata or if there was
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* no origin on upper, we can end up here.
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*/
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struct kstat lowerdatastat;
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u32 lowermask = STATX_BLOCKS;
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ovl_path_lowerdata(dentry, &realpath);
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err = vfs_getattr(&realpath, &lowerdatastat,
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lowermask, flags);
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if (err)
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goto out;
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stat->blocks = lowerdatastat.blocks;
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}
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}
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err = ovl_map_dev_ino(dentry, stat, lower_layer);
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if (err)
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goto out;
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/*
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* It's probably not worth it to count subdirs to get the
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* correct link count. nlink=1 seems to pacify 'find' and
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* other utilities.
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*/
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if (is_dir && OVL_TYPE_MERGE(type))
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stat->nlink = 1;
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/*
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* Return the overlay inode nlinks for indexed upper inodes.
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* Overlay inode nlink counts the union of the upper hardlinks
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* and non-covered lower hardlinks. It does not include the upper
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* index hardlink.
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*/
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if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
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stat->nlink = dentry->d_inode->i_nlink;
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out:
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revert_creds(old_cred);
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return err;
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}
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int ovl_permission(struct inode *inode, int mask)
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{
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struct inode *upperinode = ovl_inode_upper(inode);
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struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
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const struct cred *old_cred;
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int err;
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/* Careful in RCU walk mode */
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if (!realinode) {
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WARN_ON(!(mask & MAY_NOT_BLOCK));
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return -ECHILD;
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}
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/*
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* Check overlay inode with the creds of task and underlying inode
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* with creds of mounter
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*/
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err = generic_permission(inode, mask);
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if (err)
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return err;
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/* No need to do any access on underlying for special files */
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if (special_file(realinode->i_mode))
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return 0;
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/* No need to access underlying for execute */
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mask &= ~MAY_EXEC;
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if ((mask & (MAY_READ | MAY_WRITE)) == 0)
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return 0;
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/* Lower files get copied up, so turn write access into read */
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if (!upperinode && mask & MAY_WRITE) {
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mask &= ~(MAY_WRITE | MAY_APPEND);
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mask |= MAY_READ;
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}
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old_cred = ovl_override_creds(inode->i_sb);
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err = inode_permission(realinode, mask);
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revert_creds(old_cred);
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return err;
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}
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static const char *ovl_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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const struct cred *old_cred;
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const char *p;
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if (!dentry)
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return ERR_PTR(-ECHILD);
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old_cred = ovl_override_creds(dentry->d_sb);
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p = vfs_get_link(ovl_dentry_real(dentry), done);
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revert_creds(old_cred);
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return p;
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}
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bool ovl_is_private_xattr(const char *name)
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{
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return strncmp(name, OVL_XATTR_PREFIX,
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sizeof(OVL_XATTR_PREFIX) - 1) == 0;
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}
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int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
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const void *value, size_t size, int flags)
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{
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int err;
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struct dentry *upperdentry = ovl_i_dentry_upper(inode);
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struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
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const struct cred *old_cred;
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err = ovl_want_write(dentry);
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if (err)
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goto out;
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if (!value && !upperdentry) {
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err = vfs_getxattr(realdentry, name, NULL, 0);
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if (err < 0)
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goto out_drop_write;
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}
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if (!upperdentry) {
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err = ovl_copy_up(dentry);
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if (err)
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goto out_drop_write;
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realdentry = ovl_dentry_upper(dentry);
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}
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old_cred = ovl_override_creds(dentry->d_sb);
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if (value)
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err = vfs_setxattr(realdentry, name, value, size, flags);
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else {
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WARN_ON(flags != XATTR_REPLACE);
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err = vfs_removexattr(realdentry, name);
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}
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revert_creds(old_cred);
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/* copy c/mtime */
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ovl_copyattr(d_inode(realdentry), inode);
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out_drop_write:
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ovl_drop_write(dentry);
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out:
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return err;
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}
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int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
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void *value, size_t size)
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{
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ssize_t res;
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const struct cred *old_cred;
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struct dentry *realdentry =
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ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);
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old_cred = ovl_override_creds(dentry->d_sb);
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res = vfs_getxattr(realdentry, name, value, size);
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revert_creds(old_cred);
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return res;
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}
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static bool ovl_can_list(const char *s)
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{
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/* List all non-trusted xatts */
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if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
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return true;
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/* Never list trusted.overlay, list other trusted for superuser only */
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return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
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}
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ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
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{
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struct dentry *realdentry = ovl_dentry_real(dentry);
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ssize_t res;
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size_t len;
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char *s;
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const struct cred *old_cred;
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old_cred = ovl_override_creds(dentry->d_sb);
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res = vfs_listxattr(realdentry, list, size);
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revert_creds(old_cred);
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if (res <= 0 || size == 0)
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return res;
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/* filter out private xattrs */
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for (s = list, len = res; len;) {
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size_t slen = strnlen(s, len) + 1;
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/* underlying fs providing us with an broken xattr list? */
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if (WARN_ON(slen > len))
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return -EIO;
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|
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len -= slen;
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if (!ovl_can_list(s)) {
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res -= slen;
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memmove(s, s + slen, len);
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} else {
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s += slen;
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}
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}
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|
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return res;
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}
|
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|
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struct posix_acl *ovl_get_acl(struct inode *inode, int type)
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{
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struct inode *realinode = ovl_inode_real(inode);
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const struct cred *old_cred;
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struct posix_acl *acl;
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|
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if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode))
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return NULL;
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|
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old_cred = ovl_override_creds(inode->i_sb);
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acl = get_acl(realinode, type);
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revert_creds(old_cred);
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|
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return acl;
|
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}
|
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|
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int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
|
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{
|
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if (flags & S_ATIME) {
|
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struct ovl_fs *ofs = inode->i_sb->s_fs_info;
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struct path upperpath = {
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.mnt = ofs->upper_mnt,
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.dentry = ovl_upperdentry_dereference(OVL_I(inode)),
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};
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|
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if (upperpath.dentry) {
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touch_atime(&upperpath);
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inode->i_atime = d_inode(upperpath.dentry)->i_atime;
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}
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}
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return 0;
|
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}
|
|
|
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static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
|
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u64 start, u64 len)
|
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{
|
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int err;
|
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struct inode *realinode = ovl_inode_real(inode);
|
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const struct cred *old_cred;
|
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|
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if (!realinode->i_op->fiemap)
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return -EOPNOTSUPP;
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|
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old_cred = ovl_override_creds(inode->i_sb);
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|
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if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
|
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filemap_write_and_wait(realinode->i_mapping);
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|
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err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
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revert_creds(old_cred);
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|
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return err;
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}
|
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|
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static const struct inode_operations ovl_file_inode_operations = {
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.setattr = ovl_setattr,
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.permission = ovl_permission,
|
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.getattr = ovl_getattr,
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.listxattr = ovl_listxattr,
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.get_acl = ovl_get_acl,
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.update_time = ovl_update_time,
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.fiemap = ovl_fiemap,
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};
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|
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static const struct inode_operations ovl_symlink_inode_operations = {
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.setattr = ovl_setattr,
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.get_link = ovl_get_link,
|
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.getattr = ovl_getattr,
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.listxattr = ovl_listxattr,
|
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.update_time = ovl_update_time,
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};
|
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|
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static const struct inode_operations ovl_special_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.permission = ovl_permission,
|
|
.getattr = ovl_getattr,
|
|
.listxattr = ovl_listxattr,
|
|
.get_acl = ovl_get_acl,
|
|
.update_time = ovl_update_time,
|
|
};
|
|
|
|
static const struct address_space_operations ovl_aops = {
|
|
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
|
|
.direct_IO = noop_direct_IO,
|
|
};
|
|
|
|
/*
|
|
* It is possible to stack overlayfs instance on top of another
|
|
* overlayfs instance as lower layer. We need to annonate the
|
|
* stackable i_mutex locks according to stack level of the super
|
|
* block instance. An overlayfs instance can never be in stack
|
|
* depth 0 (there is always a real fs below it). An overlayfs
|
|
* inode lock will use the lockdep annotaion ovl_i_mutex_key[depth].
|
|
*
|
|
* For example, here is a snip from /proc/lockdep_chains after
|
|
* dir_iterate of nested overlayfs:
|
|
*
|
|
* [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
|
|
* [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
|
|
* [...] &type->i_mutex_dir_key (stack_depth=0)
|
|
*/
|
|
#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
|
|
|
|
static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
|
|
{
|
|
#ifdef CONFIG_LOCKDEP
|
|
static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING];
|
|
static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING];
|
|
static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING];
|
|
|
|
int depth = inode->i_sb->s_stack_depth - 1;
|
|
|
|
if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING))
|
|
depth = 0;
|
|
|
|
if (S_ISDIR(inode->i_mode))
|
|
lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]);
|
|
else
|
|
lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]);
|
|
|
|
lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]);
|
|
#endif
|
|
}
|
|
|
|
static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
|
|
unsigned long ino, int fsid)
|
|
{
|
|
int xinobits = ovl_xino_bits(inode->i_sb);
|
|
|
|
/*
|
|
* When NFS export is enabled and d_ino is consistent with st_ino
|
|
* (samefs or i_ino has enough bits to encode layer), set the same
|
|
* value used for d_ino to i_ino, because nfsd readdirplus compares
|
|
* d_ino values to i_ino values of child entries. When called from
|
|
* ovl_new_inode(), ino arg is 0, so i_ino will be updated to real
|
|
* upper inode i_ino on ovl_inode_init() or ovl_inode_update().
|
|
*/
|
|
if (inode->i_sb->s_export_op &&
|
|
(ovl_same_sb(inode->i_sb) || xinobits)) {
|
|
inode->i_ino = ino;
|
|
if (xinobits && fsid && !(ino >> (64 - xinobits)))
|
|
inode->i_ino |= (unsigned long)fsid << (64 - xinobits);
|
|
} else {
|
|
inode->i_ino = get_next_ino();
|
|
}
|
|
inode->i_mode = mode;
|
|
inode->i_flags |= S_NOCMTIME;
|
|
#ifdef CONFIG_FS_POSIX_ACL
|
|
inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
|
|
#endif
|
|
|
|
ovl_lockdep_annotate_inode_mutex_key(inode);
|
|
|
|
switch (mode & S_IFMT) {
|
|
case S_IFREG:
|
|
inode->i_op = &ovl_file_inode_operations;
|
|
inode->i_fop = &ovl_file_operations;
|
|
inode->i_mapping->a_ops = &ovl_aops;
|
|
break;
|
|
|
|
case S_IFDIR:
|
|
inode->i_op = &ovl_dir_inode_operations;
|
|
inode->i_fop = &ovl_dir_operations;
|
|
break;
|
|
|
|
case S_IFLNK:
|
|
inode->i_op = &ovl_symlink_inode_operations;
|
|
break;
|
|
|
|
default:
|
|
inode->i_op = &ovl_special_inode_operations;
|
|
init_special_inode(inode, mode, rdev);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* With inodes index enabled, an overlay inode nlink counts the union of upper
|
|
* hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
|
|
* upper inode, the following nlink modifying operations can happen:
|
|
*
|
|
* 1. Lower hardlink copy up
|
|
* 2. Upper hardlink created, unlinked or renamed over
|
|
* 3. Lower hardlink whiteout or renamed over
|
|
*
|
|
* For the first, copy up case, the union nlink does not change, whether the
|
|
* operation succeeds or fails, but the upper inode nlink may change.
|
|
* Therefore, before copy up, we store the union nlink value relative to the
|
|
* lower inode nlink in the index inode xattr trusted.overlay.nlink.
|
|
*
|
|
* For the second, upper hardlink case, the union nlink should be incremented
|
|
* or decremented IFF the operation succeeds, aligned with nlink change of the
|
|
* upper inode. Therefore, before link/unlink/rename, we store the union nlink
|
|
* value relative to the upper inode nlink in the index inode.
|
|
*
|
|
* For the last, lower cover up case, we simplify things by preceding the
|
|
* whiteout or cover up with copy up. This makes sure that there is an index
|
|
* upper inode where the nlink xattr can be stored before the copied up upper
|
|
* entry is unlink.
|
|
*/
|
|
#define OVL_NLINK_ADD_UPPER (1 << 0)
|
|
|
|
/*
|
|
* On-disk format for indexed nlink:
|
|
*
|
|
* nlink relative to the upper inode - "U[+-]NUM"
|
|
* nlink relative to the lower inode - "L[+-]NUM"
|
|
*/
|
|
|
|
static int ovl_set_nlink_common(struct dentry *dentry,
|
|
struct dentry *realdentry, const char *format)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
struct inode *realinode = d_inode(realdentry);
|
|
char buf[13];
|
|
int len;
|
|
|
|
len = snprintf(buf, sizeof(buf), format,
|
|
(int) (inode->i_nlink - realinode->i_nlink));
|
|
|
|
if (WARN_ON(len >= sizeof(buf)))
|
|
return -EIO;
|
|
|
|
return ovl_do_setxattr(ovl_dentry_upper(dentry),
|
|
OVL_XATTR_NLINK, buf, len, 0);
|
|
}
|
|
|
|
int ovl_set_nlink_upper(struct dentry *dentry)
|
|
{
|
|
return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
|
|
}
|
|
|
|
int ovl_set_nlink_lower(struct dentry *dentry)
|
|
{
|
|
return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
|
|
}
|
|
|
|
unsigned int ovl_get_nlink(struct dentry *lowerdentry,
|
|
struct dentry *upperdentry,
|
|
unsigned int fallback)
|
|
{
|
|
int nlink_diff;
|
|
int nlink;
|
|
char buf[13];
|
|
int err;
|
|
|
|
if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
|
|
return fallback;
|
|
|
|
err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1);
|
|
if (err < 0)
|
|
goto fail;
|
|
|
|
buf[err] = '\0';
|
|
if ((buf[0] != 'L' && buf[0] != 'U') ||
|
|
(buf[1] != '+' && buf[1] != '-'))
|
|
goto fail;
|
|
|
|
err = kstrtoint(buf + 1, 10, &nlink_diff);
|
|
if (err < 0)
|
|
goto fail;
|
|
|
|
nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
|
|
nlink += nlink_diff;
|
|
|
|
if (nlink <= 0)
|
|
goto fail;
|
|
|
|
return nlink;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n",
|
|
upperdentry, err);
|
|
return fallback;
|
|
}
|
|
|
|
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
|
|
{
|
|
struct inode *inode;
|
|
|
|
inode = new_inode(sb);
|
|
if (inode)
|
|
ovl_fill_inode(inode, mode, rdev, 0, 0);
|
|
|
|
return inode;
|
|
}
|
|
|
|
static int ovl_inode_test(struct inode *inode, void *data)
|
|
{
|
|
return inode->i_private == data;
|
|
}
|
|
|
|
static int ovl_inode_set(struct inode *inode, void *data)
|
|
{
|
|
inode->i_private = data;
|
|
return 0;
|
|
}
|
|
|
|
static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
|
|
struct dentry *upperdentry, bool strict)
|
|
{
|
|
/*
|
|
* For directories, @strict verify from lookup path performs consistency
|
|
* checks, so NULL lower/upper in dentry must match NULL lower/upper in
|
|
* inode. Non @strict verify from NFS handle decode path passes NULL for
|
|
* 'unknown' lower/upper.
|
|
*/
|
|
if (S_ISDIR(inode->i_mode) && strict) {
|
|
/* Real lower dir moved to upper layer under us? */
|
|
if (!lowerdentry && ovl_inode_lower(inode))
|
|
return false;
|
|
|
|
/* Lookup of an uncovered redirect origin? */
|
|
if (!upperdentry && ovl_inode_upper(inode))
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
|
|
* This happens when finding a copied up overlay inode for a renamed
|
|
* or hardlinked overlay dentry and lower dentry cannot be followed
|
|
* by origin because lower fs does not support file handles.
|
|
*/
|
|
if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
|
|
return false;
|
|
|
|
/*
|
|
* Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
|
|
* This happens when finding a lower alias for a copied up hard link.
|
|
*/
|
|
if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
|
|
bool is_upper)
|
|
{
|
|
struct inode *inode, *key = d_inode(real);
|
|
|
|
inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
|
|
if (!inode)
|
|
return NULL;
|
|
|
|
if (!ovl_verify_inode(inode, is_upper ? NULL : real,
|
|
is_upper ? real : NULL, false)) {
|
|
iput(inode);
|
|
return ERR_PTR(-ESTALE);
|
|
}
|
|
|
|
return inode;
|
|
}
|
|
|
|
/*
|
|
* Does overlay inode need to be hashed by lower inode?
|
|
*/
|
|
static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
|
|
struct dentry *lower, struct dentry *index)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
|
|
/* No, if pure upper */
|
|
if (!lower)
|
|
return false;
|
|
|
|
/* Yes, if already indexed */
|
|
if (index)
|
|
return true;
|
|
|
|
/* Yes, if won't be copied up */
|
|
if (!ofs->upper_mnt)
|
|
return true;
|
|
|
|
/* No, if lower hardlink is or will be broken on copy up */
|
|
if ((upper || !ovl_indexdir(sb)) &&
|
|
!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
|
|
return false;
|
|
|
|
/* No, if non-indexed upper with NFS export */
|
|
if (sb->s_export_op && upper)
|
|
return false;
|
|
|
|
/* Otherwise, hash by lower inode for fsnotify */
|
|
return true;
|
|
}
|
|
|
|
static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode,
|
|
struct inode *key)
|
|
{
|
|
return newinode ? inode_insert5(newinode, (unsigned long) key,
|
|
ovl_inode_test, ovl_inode_set, key) :
|
|
iget5_locked(sb, (unsigned long) key,
|
|
ovl_inode_test, ovl_inode_set, key);
|
|
}
|
|
|
|
struct inode *ovl_get_inode(struct super_block *sb,
|
|
struct ovl_inode_params *oip)
|
|
{
|
|
struct dentry *upperdentry = oip->upperdentry;
|
|
struct ovl_path *lowerpath = oip->lowerpath;
|
|
struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
|
|
struct inode *inode;
|
|
struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
|
|
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
|
|
oip->index);
|
|
int fsid = bylower ? oip->lowerpath->layer->fsid : 0;
|
|
bool is_dir, metacopy = false;
|
|
unsigned long ino = 0;
|
|
int err = -ENOMEM;
|
|
|
|
if (!realinode)
|
|
realinode = d_inode(lowerdentry);
|
|
|
|
/*
|
|
* Copy up origin (lower) may exist for non-indexed upper, but we must
|
|
* not use lower as hash key if this is a broken hardlink.
|
|
*/
|
|
is_dir = S_ISDIR(realinode->i_mode);
|
|
if (upperdentry || bylower) {
|
|
struct inode *key = d_inode(bylower ? lowerdentry :
|
|
upperdentry);
|
|
unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
|
|
|
|
inode = ovl_iget5(sb, oip->newinode, key);
|
|
if (!inode)
|
|
goto out_err;
|
|
if (!(inode->i_state & I_NEW)) {
|
|
/*
|
|
* Verify that the underlying files stored in the inode
|
|
* match those in the dentry.
|
|
*/
|
|
if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
|
|
true)) {
|
|
iput(inode);
|
|
err = -ESTALE;
|
|
goto out_err;
|
|
}
|
|
|
|
dput(upperdentry);
|
|
kfree(oip->redirect);
|
|
goto out;
|
|
}
|
|
|
|
/* Recalculate nlink for non-dir due to indexing */
|
|
if (!is_dir)
|
|
nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);
|
|
set_nlink(inode, nlink);
|
|
ino = key->i_ino;
|
|
} else {
|
|
/* Lower hardlink that will be broken on copy up */
|
|
inode = new_inode(sb);
|
|
if (!inode) {
|
|
err = -ENOMEM;
|
|
goto out_err;
|
|
}
|
|
}
|
|
ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid);
|
|
ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata);
|
|
|
|
if (upperdentry && ovl_is_impuredir(upperdentry))
|
|
ovl_set_flag(OVL_IMPURE, inode);
|
|
|
|
if (oip->index)
|
|
ovl_set_flag(OVL_INDEX, inode);
|
|
|
|
if (upperdentry) {
|
|
err = ovl_check_metacopy_xattr(upperdentry);
|
|
if (err < 0)
|
|
goto out_err;
|
|
metacopy = err;
|
|
if (!metacopy)
|
|
ovl_set_flag(OVL_UPPERDATA, inode);
|
|
}
|
|
|
|
OVL_I(inode)->redirect = oip->redirect;
|
|
|
|
if (bylower)
|
|
ovl_set_flag(OVL_CONST_INO, inode);
|
|
|
|
/* Check for non-merge dir that may have whiteouts */
|
|
if (is_dir) {
|
|
if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
|
|
ovl_check_origin_xattr(upperdentry ?: lowerdentry)) {
|
|
ovl_set_flag(OVL_WHITEOUTS, inode);
|
|
}
|
|
}
|
|
|
|
if (inode->i_state & I_NEW)
|
|
unlock_new_inode(inode);
|
|
out:
|
|
return inode;
|
|
|
|
out_err:
|
|
inode = ERR_PTR(err);
|
|
goto out;
|
|
}
|