// SPDX-License-Identifier: GPL-2.0-only /* * * Copyright (C) 2011 Novell Inc. */ #include <linux/fs.h> #include <linux/namei.h> #include <linux/xattr.h> #include <linux/security.h> #include <linux/cred.h> #include <linux/module.h> #include <linux/posix_acl.h> #include <linux/posix_acl_xattr.h> #include <linux/atomic.h> #include <linux/ratelimit.h> #include "overlayfs.h" static unsigned short ovl_redirect_max = 256; module_param_named(redirect_max, ovl_redirect_max, ushort, 0644); MODULE_PARM_DESC(redirect_max, "Maximum length of absolute redirect xattr value"); static int ovl_set_redirect(struct dentry *dentry, bool samedir); int ovl_cleanup(struct inode *wdir, struct dentry *wdentry) { int err; dget(wdentry); if (d_is_dir(wdentry)) err = ovl_do_rmdir(wdir, wdentry); else err = ovl_do_unlink(wdir, wdentry); dput(wdentry); if (err) { pr_err("cleanup of '%pd2' failed (%i)\n", wdentry, err); } return err; } struct dentry *ovl_lookup_temp(struct dentry *workdir) { struct dentry *temp; char name[20]; static atomic_t temp_id = ATOMIC_INIT(0); /* counter is allowed to wrap, since temp dentries are ephemeral */ snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id)); temp = lookup_one_len(name, workdir, strlen(name)); if (!IS_ERR(temp) && temp->d_inode) { pr_err("workdir/%s already exists\n", name); dput(temp); temp = ERR_PTR(-EIO); } return temp; } /* caller holds i_mutex on workdir */ static struct dentry *ovl_whiteout(struct ovl_fs *ofs) { int err; struct dentry *whiteout; struct dentry *workdir = ofs->workdir; struct inode *wdir = workdir->d_inode; if (!ofs->whiteout) { whiteout = ovl_lookup_temp(workdir); if (IS_ERR(whiteout)) goto out; err = ovl_do_whiteout(wdir, whiteout); if (err) { dput(whiteout); whiteout = ERR_PTR(err); goto out; } ofs->whiteout = whiteout; } if (ofs->share_whiteout) { whiteout = ovl_lookup_temp(workdir); if (IS_ERR(whiteout)) goto out; err = ovl_do_link(ofs->whiteout, wdir, whiteout); if (!err) goto out; if (err != -EMLINK) { pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n", ofs->whiteout->d_inode->i_nlink, err); ofs->share_whiteout = false; } dput(whiteout); } whiteout = ofs->whiteout; ofs->whiteout = NULL; out: return whiteout; } /* Caller must hold i_mutex on both workdir and dir */ int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir, struct dentry *dentry) { struct inode *wdir = ofs->workdir->d_inode; struct dentry *whiteout; int err; int flags = 0; whiteout = ovl_whiteout(ofs); err = PTR_ERR(whiteout); if (IS_ERR(whiteout)) return err; if (d_is_dir(dentry)) flags = RENAME_EXCHANGE; err = ovl_do_rename(wdir, whiteout, dir, dentry, flags); if (err) goto kill_whiteout; if (flags) ovl_cleanup(wdir, dentry); out: dput(whiteout); return err; kill_whiteout: ovl_cleanup(wdir, whiteout); goto out; } int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry, umode_t mode) { int err; struct dentry *d, *dentry = *newdentry; err = ovl_do_mkdir(dir, dentry, mode); if (err) return err; if (likely(!d_unhashed(dentry))) return 0; /* * vfs_mkdir() may succeed and leave the dentry passed * to it unhashed and negative. If that happens, try to * lookup a new hashed and positive dentry. */ d = lookup_one_len(dentry->d_name.name, dentry->d_parent, dentry->d_name.len); if (IS_ERR(d)) { pr_warn("failed lookup after mkdir (%pd2, err=%i).\n", dentry, err); return PTR_ERR(d); } dput(dentry); *newdentry = d; return 0; } struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry, struct ovl_cattr *attr) { int err; if (IS_ERR(newdentry)) return newdentry; err = -ESTALE; if (newdentry->d_inode) goto out; if (attr->hardlink) { err = ovl_do_link(attr->hardlink, dir, newdentry); } else { switch (attr->mode & S_IFMT) { case S_IFREG: err = ovl_do_create(dir, newdentry, attr->mode); break; case S_IFDIR: /* mkdir is special... */ err = ovl_mkdir_real(dir, &newdentry, attr->mode); break; case S_IFCHR: case S_IFBLK: case S_IFIFO: case S_IFSOCK: err = ovl_do_mknod(dir, newdentry, attr->mode, attr->rdev); break; case S_IFLNK: err = ovl_do_symlink(dir, newdentry, attr->link); break; default: err = -EPERM; } } if (!err && WARN_ON(!newdentry->d_inode)) { /* * Not quite sure if non-instantiated dentry is legal or not. * VFS doesn't seem to care so check and warn here. */ err = -EIO; } out: if (err) { dput(newdentry); return ERR_PTR(err); } return newdentry; } struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr) { return ovl_create_real(d_inode(workdir), ovl_lookup_temp(workdir), attr); } static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper, int xerr) { struct ovl_fs *ofs = OVL_FS(dentry->d_sb); int err; err = ovl_check_setxattr(ofs, upper, OVL_XATTR_OPAQUE, "y", 1, xerr); if (!err) ovl_dentry_set_opaque(dentry); return err; } static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry) { /* * Fail with -EIO when trying to create opaque dir and upper doesn't * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to * return a specific error for noxattr case. */ return ovl_set_opaque_xerr(dentry, upperdentry, -EIO); } /* * Common operations required to be done after creation of file on upper. * If @hardlink is false, then @inode is a pre-allocated inode, we may or * may not use to instantiate the new dentry. */ static int ovl_instantiate(struct dentry *dentry, struct inode *inode, struct dentry *newdentry, bool hardlink) { struct ovl_inode_params oip = { .upperdentry = newdentry, .newinode = inode, }; ovl_dir_modified(dentry->d_parent, false); ovl_dentry_set_upper_alias(dentry); ovl_dentry_update_reval(dentry, newdentry, DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); if (!hardlink) { /* * ovl_obtain_alias() can be called after ovl_create_real() * and before we get here, so we may get an inode from cache * with the same real upperdentry that is not the inode we * pre-allocated. In this case we will use the cached inode * to instantiate the new dentry. * * XXX: if we ever use ovl_obtain_alias() to decode directory * file handles, need to use ovl_get_inode_locked() and * d_instantiate_new() here to prevent from creating two * hashed directory inode aliases. */ inode = ovl_get_inode(dentry->d_sb, &oip); if (IS_ERR(inode)) return PTR_ERR(inode); if (inode == oip.newinode) ovl_set_flag(OVL_UPPERDATA, inode); } else { WARN_ON(ovl_inode_real(inode) != d_inode(newdentry)); dput(newdentry); inc_nlink(inode); } d_instantiate(dentry, inode); if (inode != oip.newinode) { pr_warn_ratelimited("newly created inode found in cache (%pd2)\n", dentry); } /* Force lookup of new upper hardlink to find its lower */ if (hardlink) d_drop(dentry); return 0; } static bool ovl_type_merge(struct dentry *dentry) { return OVL_TYPE_MERGE(ovl_path_type(dentry)); } static bool ovl_type_origin(struct dentry *dentry) { return OVL_TYPE_ORIGIN(ovl_path_type(dentry)); } static int ovl_create_upper(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr) { struct ovl_fs *ofs = OVL_FS(dentry->d_sb); struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); struct inode *udir = upperdir->d_inode; struct dentry *newdentry; int err; if (!attr->hardlink && !IS_POSIXACL(udir)) attr->mode &= ~current_umask(); inode_lock_nested(udir, I_MUTEX_PARENT); newdentry = ovl_create_real(udir, lookup_one_len(dentry->d_name.name, upperdir, dentry->d_name.len), attr); err = PTR_ERR(newdentry); if (IS_ERR(newdentry)) goto out_unlock; if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) && !ovl_allow_offline_changes(ofs)) { /* Setting opaque here is just an optimization, allow to fail */ ovl_set_opaque(dentry, newdentry); } err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink); if (err) goto out_cleanup; out_unlock: inode_unlock(udir); return err; out_cleanup: ovl_cleanup(udir, newdentry); dput(newdentry); goto out_unlock; } static struct dentry *ovl_clear_empty(struct dentry *dentry, struct list_head *list) { struct dentry *workdir = ovl_workdir(dentry); struct inode *wdir = workdir->d_inode; struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); struct inode *udir = upperdir->d_inode; struct path upperpath; struct dentry *upper; struct dentry *opaquedir; struct kstat stat; int err; if (WARN_ON(!workdir)) return ERR_PTR(-EROFS); err = ovl_lock_rename_workdir(workdir, upperdir); if (err) goto out; ovl_path_upper(dentry, &upperpath); err = vfs_getattr(&upperpath, &stat, STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT); if (err) goto out_unlock; err = -ESTALE; if (!S_ISDIR(stat.mode)) goto out_unlock; upper = upperpath.dentry; if (upper->d_parent->d_inode != udir) goto out_unlock; opaquedir = ovl_create_temp(workdir, OVL_CATTR(stat.mode)); err = PTR_ERR(opaquedir); if (IS_ERR(opaquedir)) goto out_unlock; err = ovl_copy_xattr(dentry->d_sb, upper, opaquedir); if (err) goto out_cleanup; err = ovl_set_opaque(dentry, opaquedir); if (err) goto out_cleanup; inode_lock(opaquedir->d_inode); err = ovl_set_attr(opaquedir, &stat); inode_unlock(opaquedir->d_inode); if (err) goto out_cleanup; err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE); if (err) goto out_cleanup; ovl_cleanup_whiteouts(upper, list); ovl_cleanup(wdir, upper); unlock_rename(workdir, upperdir); /* dentry's upper doesn't match now, get rid of it */ d_drop(dentry); return opaquedir; out_cleanup: ovl_cleanup(wdir, opaquedir); dput(opaquedir); out_unlock: unlock_rename(workdir, upperdir); out: return ERR_PTR(err); } static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name, const struct posix_acl *acl) { void *buffer; size_t size; int err; if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl) return 0; size = posix_acl_xattr_size(acl->a_count); buffer = kmalloc(size, GFP_KERNEL); if (!buffer) return -ENOMEM; err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size); if (err < 0) goto out_free; err = vfs_setxattr(&init_user_ns, upperdentry, name, buffer, size, XATTR_CREATE); out_free: kfree(buffer); return err; } static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, struct ovl_cattr *cattr) { struct dentry *workdir = ovl_workdir(dentry); struct inode *wdir = workdir->d_inode; struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); struct inode *udir = upperdir->d_inode; struct dentry *upper; struct dentry *newdentry; int err; struct posix_acl *acl, *default_acl; bool hardlink = !!cattr->hardlink; if (WARN_ON(!workdir)) return -EROFS; if (!hardlink) { err = posix_acl_create(dentry->d_parent->d_inode, &cattr->mode, &default_acl, &acl); if (err) return err; } err = ovl_lock_rename_workdir(workdir, upperdir); if (err) goto out; upper = lookup_one_len(dentry->d_name.name, upperdir, dentry->d_name.len); err = PTR_ERR(upper); if (IS_ERR(upper)) goto out_unlock; err = -ESTALE; if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper))) goto out_dput; newdentry = ovl_create_temp(workdir, cattr); err = PTR_ERR(newdentry); if (IS_ERR(newdentry)) goto out_dput; /* * mode could have been mutilated due to umask (e.g. sgid directory) */ if (!hardlink && !S_ISLNK(cattr->mode) && newdentry->d_inode->i_mode != cattr->mode) { struct iattr attr = { .ia_valid = ATTR_MODE, .ia_mode = cattr->mode, }; inode_lock(newdentry->d_inode); err = notify_change(&init_user_ns, newdentry, &attr, NULL); inode_unlock(newdentry->d_inode); if (err) goto out_cleanup; } if (!hardlink) { err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS, acl); if (err) goto out_cleanup; err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT, default_acl); if (err) goto out_cleanup; } if (!hardlink && S_ISDIR(cattr->mode)) { err = ovl_set_opaque(dentry, newdentry); if (err) goto out_cleanup; err = ovl_do_rename(wdir, newdentry, udir, upper, RENAME_EXCHANGE); if (err) goto out_cleanup; ovl_cleanup(wdir, upper); } else { err = ovl_do_rename(wdir, newdentry, udir, upper, 0); if (err) goto out_cleanup; } err = ovl_instantiate(dentry, inode, newdentry, hardlink); if (err) { ovl_cleanup(udir, newdentry); dput(newdentry); } out_dput: dput(upper); out_unlock: unlock_rename(workdir, upperdir); out: if (!hardlink) { posix_acl_release(acl); posix_acl_release(default_acl); } return err; out_cleanup: ovl_cleanup(wdir, newdentry); dput(newdentry); goto out_dput; } static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr, bool origin) { int err; const struct cred *old_cred; struct cred *override_cred; struct dentry *parent = dentry->d_parent; err = ovl_copy_up(parent); if (err) return err; old_cred = ovl_override_creds(dentry->d_sb); /* * When linking a file with copy up origin into a new parent, mark the * new parent dir "impure". */ if (origin) { err = ovl_set_impure(parent, ovl_dentry_upper(parent)); if (err) goto out_revert_creds; } err = -ENOMEM; override_cred = prepare_creds(); if (override_cred) { override_cred->fsuid = inode->i_uid; override_cred->fsgid = inode->i_gid; if (!attr->hardlink) { err = security_dentry_create_files_as(dentry, attr->mode, &dentry->d_name, old_cred, override_cred); if (err) { put_cred(override_cred); goto out_revert_creds; } } put_cred(override_creds(override_cred)); put_cred(override_cred); if (!ovl_dentry_is_whiteout(dentry)) err = ovl_create_upper(dentry, inode, attr); else err = ovl_create_over_whiteout(dentry, inode, attr); } out_revert_creds: revert_creds(old_cred); return err; } static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, const char *link) { int err; struct inode *inode; struct ovl_cattr attr = { .rdev = rdev, .link = link, }; err = ovl_want_write(dentry); if (err) goto out; /* Preallocate inode to be used by ovl_get_inode() */ err = -ENOMEM; inode = ovl_new_inode(dentry->d_sb, mode, rdev); if (!inode) goto out_drop_write; spin_lock(&inode->i_lock); inode->i_state |= I_CREATING; spin_unlock(&inode->i_lock); inode_init_owner(&init_user_ns, inode, dentry->d_parent->d_inode, mode); attr.mode = inode->i_mode; err = ovl_create_or_link(dentry, inode, &attr, false); /* Did we end up using the preallocated inode? */ if (inode != d_inode(dentry)) iput(inode); out_drop_write: ovl_drop_write(dentry); out: return err; } static int ovl_create(struct user_namespace *mnt_userns, struct inode *dir, struct dentry *dentry, umode_t mode, bool excl) { return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); } static int ovl_mkdir(struct user_namespace *mnt_userns, struct inode *dir, struct dentry *dentry, umode_t mode) { return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); } static int ovl_mknod(struct user_namespace *mnt_userns, struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev) { /* Don't allow creation of "whiteout" on overlay */ if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) return -EPERM; return ovl_create_object(dentry, mode, rdev, NULL); } static int ovl_symlink(struct user_namespace *mnt_userns, struct inode *dir, struct dentry *dentry, const char *link) { return ovl_create_object(dentry, S_IFLNK, 0, link); } static int ovl_set_link_redirect(struct dentry *dentry) { const struct cred *old_cred; int err; old_cred = ovl_override_creds(dentry->d_sb); err = ovl_set_redirect(dentry, false); revert_creds(old_cred); return err; } static int ovl_link(struct dentry *old, struct inode *newdir, struct dentry *new) { int err; struct inode *inode; err = ovl_want_write(old); if (err) goto out; err = ovl_copy_up(old); if (err) goto out_drop_write; err = ovl_copy_up(new->d_parent); if (err) goto out_drop_write; if (ovl_is_metacopy_dentry(old)) { err = ovl_set_link_redirect(old); if (err) goto out_drop_write; } err = ovl_nlink_start(old); if (err) goto out_drop_write; inode = d_inode(old); ihold(inode); err = ovl_create_or_link(new, inode, &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)}, ovl_type_origin(old)); if (err) iput(inode); ovl_nlink_end(old); out_drop_write: ovl_drop_write(old); out: return err; } static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper) { return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper); } static int ovl_remove_and_whiteout(struct dentry *dentry, struct list_head *list) { struct ovl_fs *ofs = OVL_FS(dentry->d_sb); struct dentry *workdir = ovl_workdir(dentry); struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); struct dentry *upper; struct dentry *opaquedir = NULL; int err; if (WARN_ON(!workdir)) return -EROFS; if (!list_empty(list)) { opaquedir = ovl_clear_empty(dentry, list); err = PTR_ERR(opaquedir); if (IS_ERR(opaquedir)) goto out; } err = ovl_lock_rename_workdir(workdir, upperdir); if (err) goto out_dput; upper = lookup_one_len(dentry->d_name.name, upperdir, dentry->d_name.len); err = PTR_ERR(upper); if (IS_ERR(upper)) goto out_unlock; err = -ESTALE; if ((opaquedir && upper != opaquedir) || (!opaquedir && ovl_dentry_upper(dentry) && !ovl_matches_upper(dentry, upper))) { goto out_dput_upper; } err = ovl_cleanup_and_whiteout(ofs, d_inode(upperdir), upper); if (err) goto out_d_drop; ovl_dir_modified(dentry->d_parent, true); out_d_drop: d_drop(dentry); out_dput_upper: dput(upper); out_unlock: unlock_rename(workdir, upperdir); out_dput: dput(opaquedir); out: return err; } static int ovl_remove_upper(struct dentry *dentry, bool is_dir, struct list_head *list) { struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); struct inode *dir = upperdir->d_inode; struct dentry *upper; struct dentry *opaquedir = NULL; int err; if (!list_empty(list)) { opaquedir = ovl_clear_empty(dentry, list); err = PTR_ERR(opaquedir); if (IS_ERR(opaquedir)) goto out; } inode_lock_nested(dir, I_MUTEX_PARENT); upper = lookup_one_len(dentry->d_name.name, upperdir, dentry->d_name.len); err = PTR_ERR(upper); if (IS_ERR(upper)) goto out_unlock; err = -ESTALE; if ((opaquedir && upper != opaquedir) || (!opaquedir && !ovl_matches_upper(dentry, upper))) goto out_dput_upper; if (is_dir) err = vfs_rmdir(&init_user_ns, dir, upper); else err = vfs_unlink(&init_user_ns, dir, upper, NULL); ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry)); /* * Keeping this dentry hashed would mean having to release * upperpath/lowerpath, which could only be done if we are the * sole user of this dentry. Too tricky... Just unhash for * now. */ if (!err) d_drop(dentry); out_dput_upper: dput(upper); out_unlock: inode_unlock(dir); dput(opaquedir); out: return err; } static bool ovl_pure_upper(struct dentry *dentry) { return !ovl_dentry_lower(dentry) && !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry)); } static void ovl_drop_nlink(struct dentry *dentry) { struct inode *inode = d_inode(dentry); struct dentry *alias; /* Try to find another, hashed alias */ spin_lock(&inode->i_lock); hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { if (alias != dentry && !d_unhashed(alias)) break; } spin_unlock(&inode->i_lock); /* * Changes to underlying layers may cause i_nlink to lose sync with * reality. In this case prevent the link count from going to zero * prematurely. */ if (inode->i_nlink > !!alias) drop_nlink(inode); } static int ovl_do_remove(struct dentry *dentry, bool is_dir) { int err; const struct cred *old_cred; struct dentry *upperdentry; bool lower_positive = ovl_lower_positive(dentry); LIST_HEAD(list); /* No need to clean pure upper removed by vfs_rmdir() */ if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) { err = ovl_check_empty_dir(dentry, &list); if (err) goto out; } err = ovl_want_write(dentry); if (err) goto out; err = ovl_copy_up(dentry->d_parent); if (err) goto out_drop_write; err = ovl_nlink_start(dentry); if (err) goto out_drop_write; old_cred = ovl_override_creds(dentry->d_sb); if (!lower_positive) err = ovl_remove_upper(dentry, is_dir, &list); else err = ovl_remove_and_whiteout(dentry, &list); revert_creds(old_cred); if (!err) { if (is_dir) clear_nlink(dentry->d_inode); else ovl_drop_nlink(dentry); } ovl_nlink_end(dentry); /* * Copy ctime * * Note: we fail to update ctime if there was no copy-up, only a * whiteout */ upperdentry = ovl_dentry_upper(dentry); if (upperdentry) ovl_copyattr(d_inode(upperdentry), d_inode(dentry)); out_drop_write: ovl_drop_write(dentry); out: ovl_cache_free(&list); return err; } static int ovl_unlink(struct inode *dir, struct dentry *dentry) { return ovl_do_remove(dentry, false); } static int ovl_rmdir(struct inode *dir, struct dentry *dentry) { return ovl_do_remove(dentry, true); } static bool ovl_type_merge_or_lower(struct dentry *dentry) { enum ovl_path_type type = ovl_path_type(dentry); return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type); } static bool ovl_can_move(struct dentry *dentry) { return ovl_redirect_dir(dentry->d_sb) || !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry); } static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect) { char *buf, *ret; struct dentry *d, *tmp; int buflen = ovl_redirect_max + 1; if (!abs_redirect) { ret = kstrndup(dentry->d_name.name, dentry->d_name.len, GFP_KERNEL); goto out; } buf = ret = kmalloc(buflen, GFP_KERNEL); if (!buf) goto out; buflen--; buf[buflen] = '\0'; for (d = dget(dentry); !IS_ROOT(d);) { const char *name; int thislen; spin_lock(&d->d_lock); name = ovl_dentry_get_redirect(d); if (name) { thislen = strlen(name); } else { name = d->d_name.name; thislen = d->d_name.len; } /* If path is too long, fall back to userspace move */ if (thislen + (name[0] != '/') > buflen) { ret = ERR_PTR(-EXDEV); spin_unlock(&d->d_lock); goto out_put; } buflen -= thislen; memcpy(&buf[buflen], name, thislen); spin_unlock(&d->d_lock); tmp = dget_parent(d); dput(d); d = tmp; /* Absolute redirect: finished */ if (buf[buflen] == '/') break; buflen--; buf[buflen] = '/'; } ret = kstrdup(&buf[buflen], GFP_KERNEL); out_put: dput(d); kfree(buf); out: return ret ? ret : ERR_PTR(-ENOMEM); } static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir) { struct dentry *lowerdentry; if (!samedir) return true; if (d_is_dir(dentry)) return false; /* * For non-dir hardlinked files, we need absolute redirects * in general as two upper hardlinks could be in different * dirs. We could put a relative redirect now and convert * it to absolute redirect later. But when nlink > 1 and * indexing is on, that means relative redirect needs to be * converted to absolute during copy up of another lower * hardllink as well. * * So without optimizing too much, just check if lower is * a hard link or not. If lower is hard link, put absolute * redirect. */ lowerdentry = ovl_dentry_lower(dentry); return (d_inode(lowerdentry)->i_nlink > 1); } static int ovl_set_redirect(struct dentry *dentry, bool samedir) { int err; struct ovl_fs *ofs = OVL_FS(dentry->d_sb); const char *redirect = ovl_dentry_get_redirect(dentry); bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir); if (redirect && (!absolute_redirect || redirect[0] == '/')) return 0; redirect = ovl_get_redirect(dentry, absolute_redirect); if (IS_ERR(redirect)) return PTR_ERR(redirect); err = ovl_check_setxattr(ofs, ovl_dentry_upper(dentry), OVL_XATTR_REDIRECT, redirect, strlen(redirect), -EXDEV); if (!err) { spin_lock(&dentry->d_lock); ovl_dentry_set_redirect(dentry, redirect); spin_unlock(&dentry->d_lock); } else { kfree(redirect); pr_warn_ratelimited("failed to set redirect (%i)\n", err); /* Fall back to userspace copy-up */ err = -EXDEV; } return err; } static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir, struct dentry *old, struct inode *newdir, struct dentry *new, unsigned int flags) { int err; struct dentry *old_upperdir; struct dentry *new_upperdir; struct dentry *olddentry; struct dentry *newdentry; struct dentry *trap; bool old_opaque; bool new_opaque; bool cleanup_whiteout = false; bool update_nlink = false; bool overwrite = !(flags & RENAME_EXCHANGE); bool is_dir = d_is_dir(old); bool new_is_dir = d_is_dir(new); bool samedir = olddir == newdir; struct dentry *opaquedir = NULL; const struct cred *old_cred = NULL; LIST_HEAD(list); err = -EINVAL; if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) goto out; flags &= ~RENAME_NOREPLACE; /* Don't copy up directory trees */ err = -EXDEV; if (!ovl_can_move(old)) goto out; if (!overwrite && !ovl_can_move(new)) goto out; if (overwrite && new_is_dir && !ovl_pure_upper(new)) { err = ovl_check_empty_dir(new, &list); if (err) goto out; } if (overwrite) { if (ovl_lower_positive(old)) { if (!ovl_dentry_is_whiteout(new)) { /* Whiteout source */ flags |= RENAME_WHITEOUT; } else { /* Switch whiteouts */ flags |= RENAME_EXCHANGE; } } else if (is_dir && ovl_dentry_is_whiteout(new)) { flags |= RENAME_EXCHANGE; cleanup_whiteout = true; } } err = ovl_want_write(old); if (err) goto out; err = ovl_copy_up(old); if (err) goto out_drop_write; err = ovl_copy_up(new->d_parent); if (err) goto out_drop_write; if (!overwrite) { err = ovl_copy_up(new); if (err) goto out_drop_write; } else if (d_inode(new)) { err = ovl_nlink_start(new); if (err) goto out_drop_write; update_nlink = true; } old_cred = ovl_override_creds(old->d_sb); if (!list_empty(&list)) { opaquedir = ovl_clear_empty(new, &list); err = PTR_ERR(opaquedir); if (IS_ERR(opaquedir)) { opaquedir = NULL; goto out_revert_creds; } } old_upperdir = ovl_dentry_upper(old->d_parent); new_upperdir = ovl_dentry_upper(new->d_parent); if (!samedir) { /* * When moving a merge dir or non-dir with copy up origin into * a new parent, we are marking the new parent dir "impure". * When ovl_iterate() iterates an "impure" upper dir, it will * lookup the origin inodes of the entries to fill d_ino. */ if (ovl_type_origin(old)) { err = ovl_set_impure(new->d_parent, new_upperdir); if (err) goto out_revert_creds; } if (!overwrite && ovl_type_origin(new)) { err = ovl_set_impure(old->d_parent, old_upperdir); if (err) goto out_revert_creds; } } trap = lock_rename(new_upperdir, old_upperdir); olddentry = lookup_one_len(old->d_name.name, old_upperdir, old->d_name.len); err = PTR_ERR(olddentry); if (IS_ERR(olddentry)) goto out_unlock; err = -ESTALE; if (!ovl_matches_upper(old, olddentry)) goto out_dput_old; newdentry = lookup_one_len(new->d_name.name, new_upperdir, new->d_name.len); err = PTR_ERR(newdentry); if (IS_ERR(newdentry)) goto out_dput_old; old_opaque = ovl_dentry_is_opaque(old); new_opaque = ovl_dentry_is_opaque(new); err = -ESTALE; if (d_inode(new) && ovl_dentry_upper(new)) { if (opaquedir) { if (newdentry != opaquedir) goto out_dput; } else { if (!ovl_matches_upper(new, newdentry)) goto out_dput; } } else { if (!d_is_negative(newdentry)) { if (!new_opaque || !ovl_is_whiteout(newdentry)) goto out_dput; } else { if (flags & RENAME_EXCHANGE) goto out_dput; } } if (olddentry == trap) goto out_dput; if (newdentry == trap) goto out_dput; if (olddentry->d_inode == newdentry->d_inode) goto out_dput; err = 0; if (ovl_type_merge_or_lower(old)) err = ovl_set_redirect(old, samedir); else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent)) err = ovl_set_opaque_xerr(old, olddentry, -EXDEV); if (err) goto out_dput; if (!overwrite && ovl_type_merge_or_lower(new)) err = ovl_set_redirect(new, samedir); else if (!overwrite && new_is_dir && !new_opaque && ovl_type_merge(old->d_parent)) err = ovl_set_opaque_xerr(new, newdentry, -EXDEV); if (err) goto out_dput; err = ovl_do_rename(old_upperdir->d_inode, olddentry, new_upperdir->d_inode, newdentry, flags); if (err) goto out_dput; if (cleanup_whiteout) ovl_cleanup(old_upperdir->d_inode, newdentry); if (overwrite && d_inode(new)) { if (new_is_dir) clear_nlink(d_inode(new)); else ovl_drop_nlink(new); } ovl_dir_modified(old->d_parent, ovl_type_origin(old) || (!overwrite && ovl_type_origin(new))); ovl_dir_modified(new->d_parent, ovl_type_origin(old) || (d_inode(new) && ovl_type_origin(new))); /* copy ctime: */ ovl_copyattr(d_inode(olddentry), d_inode(old)); if (d_inode(new) && ovl_dentry_upper(new)) ovl_copyattr(d_inode(newdentry), d_inode(new)); out_dput: dput(newdentry); out_dput_old: dput(olddentry); out_unlock: unlock_rename(new_upperdir, old_upperdir); out_revert_creds: revert_creds(old_cred); if (update_nlink) ovl_nlink_end(new); out_drop_write: ovl_drop_write(old); out: dput(opaquedir); ovl_cache_free(&list); return err; } const struct inode_operations ovl_dir_inode_operations = { .lookup = ovl_lookup, .mkdir = ovl_mkdir, .symlink = ovl_symlink, .unlink = ovl_unlink, .rmdir = ovl_rmdir, .rename = ovl_rename, .link = ovl_link, .setattr = ovl_setattr, .create = ovl_create, .mknod = ovl_mknod, .permission = ovl_permission, .getattr = ovl_getattr, .listxattr = ovl_listxattr, .get_acl = ovl_get_acl, .update_time = ovl_update_time, .fileattr_get = ovl_fileattr_get, .fileattr_set = ovl_fileattr_set, };