| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Amir Goldstein | 2875 | 43.39% | 82 | 38.68% |
| Miklos Szeredi | 2308 | 34.83% | 71 | 33.49% |
| Christian Brauner | 721 | 10.88% | 9 | 4.25% |
| Vivek Goyal | 291 | 4.39% | 7 | 3.30% |
| Al Viro | 71 | 1.07% | 7 | 3.30% |
| Andy Whitcroft | 67 | 1.01% | 1 | 0.47% |
| Sargun Dhillon | 50 | 0.75% | 1 | 0.47% |
| Chandan Rajendra | 28 | 0.42% | 2 | 0.94% |
| lijiazi | 27 | 0.41% | 1 | 0.47% |
| Chen Zhongjin | 22 | 0.33% | 1 | 0.47% |
| Konstantin Khlebnikov | 19 | 0.29% | 2 | 0.94% |
| hujianyang | 17 | 0.26% | 3 | 1.42% |
| Jeffle Xu | 17 | 0.26% | 1 | 0.47% |
| Alexander Larsson | 16 | 0.24% | 2 | 0.94% |
| Pavel Tikhomirov | 15 | 0.23% | 1 | 0.47% |
| Chengguang Xu | 14 | 0.21% | 3 | 1.42% |
| Erez Zadok | 9 | 0.14% | 1 | 0.47% |
| youngjun | 8 | 0.12% | 1 | 0.47% |
| Hirofumi Nakagawa | 8 | 0.12% | 1 | 0.47% |
| Andrea Righi | 6 | 0.09% | 1 | 0.47% |
| Christoph Hellwig | 5 | 0.08% | 1 | 0.47% |
| Mimi Zohar | 5 | 0.08% | 1 | 0.47% |
| Jiufei (Joyce) Xue | 4 | 0.06% | 1 | 0.47% |
| Antonio Murdaca | 3 | 0.05% | 1 | 0.47% |
| Ingo Molnar | 3 | 0.05% | 1 | 0.47% |
| Vyacheslav Yurkov | 3 | 0.05% | 1 | 0.47% |
| Song Muchun | 3 | 0.05% | 1 | 0.47% |
| Tycho Andersen | 2 | 0.03% | 1 | 0.47% |
| Arnd Bergmann | 2 | 0.03% | 1 | 0.47% |
| Linus Torvalds | 2 | 0.03% | 1 | 0.47% |
| Thomas Gleixner | 2 | 0.03% | 1 | 0.47% |
| Stefan Berger | 1 | 0.02% | 1 | 0.47% |
| William Dean | 1 | 0.02% | 1 | 0.47% |
| Li Yang | 1 | 0.02% | 1 | 0.47% |
| Total | 6626 | 212 |
// SPDX-License-Identifier: GPL-2.0-only /* * * Copyright (C) 2011 Novell Inc. */ #include <uapi/linux/magic.h> #include <linux/fs.h> #include <linux/namei.h> #include <linux/xattr.h> #include <linux/mount.h> #include <linux/parser.h> #include <linux/module.h> #include <linux/statfs.h> #include <linux/seq_file.h> #include <linux/posix_acl_xattr.h> #include <linux/exportfs.h> #include <linux/file.h> #include <linux/fs_context.h> #include <linux/fs_parser.h> #include "overlayfs.h" #include "params.h" MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); struct ovl_dir_cache; static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) { struct dentry *upper, *lower; int err; switch (type) { case D_REAL_DATA: case D_REAL_METADATA: break; default: goto bug; } if (!d_is_reg(dentry)) { /* d_real_inode() is only relevant for regular files */ return dentry; } upper = ovl_dentry_upper(dentry); if (upper && (type == D_REAL_METADATA || ovl_has_upperdata(d_inode(dentry)))) return upper; if (type == D_REAL_METADATA) { lower = ovl_dentry_lower(dentry); goto real_lower; } /* * Best effort lazy lookup of lowerdata for D_REAL_DATA case to return * the real lowerdata dentry. The only current caller of d_real() with * D_REAL_DATA is d_real_inode() from trace_uprobe and this caller is * likely going to be followed reading from the file, before placing * uprobes on offset within the file, so lowerdata should be available * when setting the uprobe. */ err = ovl_verify_lowerdata(dentry); if (err) goto bug; lower = ovl_dentry_lowerdata(dentry); if (!lower) goto bug; real_lower: /* Handle recursion into stacked lower fs */ return d_real(lower, type); bug: WARN(1, "%s(%pd4, %d): real dentry not found\n", __func__, dentry, type); return dentry; } static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak) { int ret = 1; if (!d) return 1; if (weak) { if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) ret = d->d_op->d_weak_revalidate(d, flags); } else if (d->d_flags & DCACHE_OP_REVALIDATE) { ret = d->d_op->d_revalidate(d, flags); if (!ret) { if (!(flags & LOOKUP_RCU)) d_invalidate(d); ret = -ESTALE; } } return ret; } static int ovl_dentry_revalidate_common(struct dentry *dentry, unsigned int flags, bool weak) { struct ovl_entry *oe; struct ovl_path *lowerstack; struct inode *inode = d_inode_rcu(dentry); struct dentry *upper; unsigned int i; int ret = 1; /* Careful in RCU mode */ if (!inode) return -ECHILD; oe = OVL_I_E(inode); lowerstack = ovl_lowerstack(oe); upper = ovl_i_dentry_upper(inode); if (upper) ret = ovl_revalidate_real(upper, flags, weak); for (i = 0; ret > 0 && i < ovl_numlower(oe); i++) ret = ovl_revalidate_real(lowerstack[i].dentry, flags, weak); return ret; } static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) { return ovl_dentry_revalidate_common(dentry, flags, false); } static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) { return ovl_dentry_revalidate_common(dentry, flags, true); } static const struct dentry_operations ovl_dentry_operations = { .d_real = ovl_d_real, .d_revalidate = ovl_dentry_revalidate, .d_weak_revalidate = ovl_dentry_weak_revalidate, }; static struct kmem_cache *ovl_inode_cachep; static struct inode *ovl_alloc_inode(struct super_block *sb) { struct ovl_inode *oi = alloc_inode_sb(sb, ovl_inode_cachep, GFP_KERNEL); if (!oi) return NULL; oi->cache = NULL; oi->redirect = NULL; oi->version = 0; oi->flags = 0; oi->__upperdentry = NULL; oi->lowerdata_redirect = NULL; oi->oe = NULL; mutex_init(&oi->lock); return &oi->vfs_inode; } static void ovl_free_inode(struct inode *inode) { struct ovl_inode *oi = OVL_I(inode); kfree(oi->redirect); kfree(oi->oe); mutex_destroy(&oi->lock); kmem_cache_free(ovl_inode_cachep, oi); } static void ovl_destroy_inode(struct inode *inode) { struct ovl_inode *oi = OVL_I(inode); dput(oi->__upperdentry); ovl_stack_put(ovl_lowerstack(oi->oe), ovl_numlower(oi->oe)); if (S_ISDIR(inode->i_mode)) ovl_dir_cache_free(inode); else kfree(oi->lowerdata_redirect); } static void ovl_put_super(struct super_block *sb) { struct ovl_fs *ofs = OVL_FS(sb); if (ofs) ovl_free_fs(ofs); } /* Sync real dirty inodes in upper filesystem (if it exists) */ static int ovl_sync_fs(struct super_block *sb, int wait) { struct ovl_fs *ofs = OVL_FS(sb); struct super_block *upper_sb; int ret; ret = ovl_sync_status(ofs); /* * We have to always set the err, because the return value isn't * checked in syncfs, and instead indirectly return an error via * the sb's writeback errseq, which VFS inspects after this call. */ if (ret < 0) { errseq_set(&sb->s_wb_err, -EIO); return -EIO; } if (!ret) return ret; /* * Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). * All the super blocks will be iterated, including upper_sb. * * If this is a syncfs(2) call, then we do need to call * sync_filesystem() on upper_sb, but enough if we do it when being * called with wait == 1. */ if (!wait) return 0; upper_sb = ovl_upper_mnt(ofs)->mnt_sb; down_read(&upper_sb->s_umount); ret = sync_filesystem(upper_sb); up_read(&upper_sb->s_umount); return ret; } /** * ovl_statfs * @dentry: The dentry to query * @buf: The struct kstatfs to fill in with stats * * Get the filesystem statistics. As writes always target the upper layer * filesystem pass the statfs to the upper filesystem (if it exists) */ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) { struct super_block *sb = dentry->d_sb; struct ovl_fs *ofs = OVL_FS(sb); struct dentry *root_dentry = sb->s_root; struct path path; int err; ovl_path_real(root_dentry, &path); err = vfs_statfs(&path, buf); if (!err) { buf->f_namelen = ofs->namelen; buf->f_type = OVERLAYFS_SUPER_MAGIC; if (ovl_has_fsid(ofs)) buf->f_fsid = uuid_to_fsid(sb->s_uuid.b); } return err; } static const struct super_operations ovl_super_operations = { .alloc_inode = ovl_alloc_inode, .free_inode = ovl_free_inode, .destroy_inode = ovl_destroy_inode, .drop_inode = generic_delete_inode, .put_super = ovl_put_super, .sync_fs = ovl_sync_fs, .statfs = ovl_statfs, .show_options = ovl_show_options, }; #define OVL_WORKDIR_NAME "work" #define OVL_INDEXDIR_NAME "index" static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, const char *name, bool persist) { struct inode *dir = ofs->workbasedir->d_inode; struct vfsmount *mnt = ovl_upper_mnt(ofs); struct dentry *work; int err; bool retried = false; inode_lock_nested(dir, I_MUTEX_PARENT); retry: work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name)); if (!IS_ERR(work)) { struct iattr attr = { .ia_valid = ATTR_MODE, .ia_mode = S_IFDIR | 0, }; if (work->d_inode) { err = -EEXIST; if (retried) goto out_dput; if (persist) goto out_unlock; retried = true; err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0); dput(work); if (err == -EINVAL) { work = ERR_PTR(err); goto out_unlock; } goto retry; } err = ovl_mkdir_real(ofs, dir, &work, attr.ia_mode); if (err) goto out_dput; /* Weird filesystem returning with hashed negative (kernfs)? */ err = -EINVAL; if (d_really_is_negative(work)) 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 = ovl_do_remove_acl(ofs, work, XATTR_NAME_POSIX_ACL_DEFAULT); if (err && err != -ENODATA && err != -EOPNOTSUPP) goto out_dput; err = ovl_do_remove_acl(ofs, 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 = ovl_do_notify_change(ofs, work, &attr); inode_unlock(work->d_inode); if (err) goto out_dput; } else { err = PTR_ERR(work); goto out_err; } out_unlock: inode_unlock(dir); return work; out_dput: dput(work); out_err: pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n", ofs->config.workdir, name, -err); work = NULL; goto out_unlock; } static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs, const char *name) { struct kstatfs statfs; int err = vfs_statfs(path, &statfs); if (err) pr_err("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) { int fh_type; int err; err = ovl_check_namelen(path, ofs, name); if (err) return err; *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); /* * The inodes index feature and NFS export need to encode and decode * file handles, so they require that all layers support them. */ fh_type = ovl_can_decode_fh(path->dentry->d_sb); if ((ofs->config.nfs_export || (ofs->config.index && ofs->config.upperdir)) && !fh_type) { ofs->config.index = false; ofs->config.nfs_export = false; pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", name); } ofs->nofh |= !fh_type; /* * Decoding origin file handle is required for persistent st_ino. * Without persistent st_ino, xino=auto falls back to xino=off. */ if (ofs->config.xino == OVL_XINO_AUTO && ofs->config.upperdir && !fh_type) { ofs->config.xino = OVL_XINO_OFF; pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n", name); } /* Check if lower fs has 32bit inode numbers */ if (fh_type != FILEID_INO32_GEN) ofs->xino_mode = -1; return 0; } /* 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) { struct dentry *trap = lock_rename(workdir, upperdir); if (!IS_ERR(trap)) unlock_rename(workdir, upperdir); ok = (trap == NULL); } return ok; } static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, struct inode **ptrap, const char *name) { struct inode *trap; int err; trap = ovl_get_trap_inode(sb, dir); err = PTR_ERR_OR_ZERO(trap); if (err) { if (err == -ELOOP) pr_err("conflicting %s path\n", name); return err; } *ptrap = trap; return 0; } /* * Determine how we treat concurrent use of upperdir/workdir based on the * index feature. This is papering over mount leaks of container runtimes, * for example, an old overlay mount is leaked and now its upperdir is * attempted to be used as a lower layer in a new overlay mount. */ static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) { if (ofs->config.index) { pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n", name); return -EBUSY; } else { pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n", name); return 0; } } static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, struct ovl_layer *upper_layer, const struct path *upperpath) { struct vfsmount *upper_mnt; int err; /* Upperdir path should not be r/o */ if (__mnt_is_readonly(upperpath->mnt)) { pr_err("upper fs is r/o, try multi-lower layers mount\n"); err = -EINVAL; goto out; } err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); if (err) goto out; err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, "upperdir"); if (err) goto out; upper_mnt = clone_private_mount(upperpath); err = PTR_ERR(upper_mnt); if (IS_ERR(upper_mnt)) { pr_err("failed to clone upperpath\n"); goto out; } /* Don't inherit atime flags */ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); upper_layer->mnt = upper_mnt; upper_layer->idx = 0; upper_layer->fsid = 0; /* * Inherit SB_NOSEC flag from upperdir. * * This optimization changes behavior when a security related attribute * (suid/sgid/security.*) is changed on an underlying layer. This is * okay because we don't yet have guarantees in that case, but it will * need careful treatment once we want to honour changes to underlying * filesystems. */ if (upper_mnt->mnt_sb->s_flags & SB_NOSEC) sb->s_flags |= SB_NOSEC; if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) { ofs->upperdir_locked = true; } else { err = ovl_report_in_use(ofs, "upperdir"); if (err) goto out; } err = 0; out: return err; } /* * Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and * negative values if error is encountered. */ static int ovl_check_rename_whiteout(struct ovl_fs *ofs) { struct dentry *workdir = ofs->workdir; struct inode *dir = d_inode(workdir); struct dentry *temp; struct dentry *dest; struct dentry *whiteout; struct name_snapshot name; int err; inode_lock_nested(dir, I_MUTEX_PARENT); temp = ovl_create_temp(ofs, workdir, OVL_CATTR(S_IFREG | 0)); err = PTR_ERR(temp); if (IS_ERR(temp)) goto out_unlock; dest = ovl_lookup_temp(ofs, workdir); err = PTR_ERR(dest); if (IS_ERR(dest)) { dput(temp); goto out_unlock; } /* Name is inline and stable - using snapshot as a copy helper */ take_dentry_name_snapshot(&name, temp); err = ovl_do_rename(ofs, dir, temp, dir, dest, RENAME_WHITEOUT); if (err) { if (err == -EINVAL) err = 0; goto cleanup_temp; } whiteout = ovl_lookup_upper(ofs, name.name.name, workdir, name.name.len); err = PTR_ERR(whiteout); if (IS_ERR(whiteout)) goto cleanup_temp; err = ovl_upper_is_whiteout(ofs, whiteout); /* Best effort cleanup of whiteout and temp file */ if (err) ovl_cleanup(ofs, dir, whiteout); dput(whiteout); cleanup_temp: ovl_cleanup(ofs, dir, temp); release_dentry_name_snapshot(&name); dput(temp); dput(dest); out_unlock: inode_unlock(dir); return err; } static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs, struct dentry *parent, const char *name, umode_t mode) { size_t len = strlen(name); struct dentry *child; inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); child = ovl_lookup_upper(ofs, name, parent, len); if (!IS_ERR(child) && !child->d_inode) child = ovl_create_real(ofs, parent->d_inode, child, OVL_CATTR(mode)); inode_unlock(parent->d_inode); dput(parent); return child; } /* * Creates $workdir/work/incompat/volatile/dirty file if it is not already * present. */ static int ovl_create_volatile_dirty(struct ovl_fs *ofs) { unsigned int ctr; struct dentry *d = dget(ofs->workbasedir); static const char *const volatile_path[] = { OVL_WORKDIR_NAME, "incompat", "volatile", "dirty" }; const char *const *name = volatile_path; for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) { d = ovl_lookup_or_create(ofs, d, *name, ctr > 1 ? S_IFDIR : S_IFREG); if (IS_ERR(d)) return PTR_ERR(d); } dput(d); return 0; } static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, const struct path *workpath) { struct vfsmount *mnt = ovl_upper_mnt(ofs); struct dentry *workdir; struct file *tmpfile; bool rename_whiteout; bool d_type; int fh_type; int err; err = mnt_want_write(mnt); if (err) return err; workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); err = PTR_ERR(workdir); if (IS_ERR_OR_NULL(workdir)) goto out; ofs->workdir = workdir; err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir"); if (err) goto out; /* * 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. */ err = ovl_check_d_type_supported(workpath); if (err < 0) goto out; d_type = err; if (!d_type) pr_warn("upper fs needs to support d_type.\n"); /* Check if upper/work fs supports O_TMPFILE */ tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0); ofs->tmpfile = !IS_ERR(tmpfile); if (ofs->tmpfile) fput(tmpfile); else pr_warn("upper fs does not support tmpfile.\n"); /* Check if upper/work fs supports RENAME_WHITEOUT */ err = ovl_check_rename_whiteout(ofs); if (err < 0) goto out; rename_whiteout = err; if (!rename_whiteout) pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); /* * Check if upper/work fs supports (trusted|user).overlay.* xattr */ err = ovl_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1); if (err) { pr_warn("failed to set xattr on upper\n"); ofs->noxattr = true; if (ovl_redirect_follow(ofs)) { ofs->config.redirect_mode = OVL_REDIRECT_NOFOLLOW; pr_warn("...falling back to redirect_dir=nofollow.\n"); } if (ofs->config.metacopy) { ofs->config.metacopy = false; pr_warn("...falling back to metacopy=off.\n"); } if (ofs->config.index) { ofs->config.index = false; pr_warn("...falling back to index=off.\n"); } if (ovl_has_fsid(ofs)) { ofs->config.uuid = OVL_UUID_NULL; pr_warn("...falling back to uuid=null.\n"); } /* * xattr support is required for persistent st_ino. * Without persistent st_ino, xino=auto falls back to xino=off. */ if (ofs->config.xino == OVL_XINO_AUTO) { ofs->config.xino = OVL_XINO_OFF; pr_warn("...falling back to xino=off.\n"); } if (err == -EPERM && !ofs->config.userxattr) pr_info("try mounting with 'userxattr' option\n"); err = 0; } else { ovl_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE); } /* * We allowed sub-optimal upper fs configuration and don't want to break * users over kernel upgrade, but we never allowed remote upper fs, so * we can enforce strict requirements for remote upper fs. */ if (ovl_dentry_remote(ofs->workdir) && (!d_type || !rename_whiteout || ofs->noxattr)) { pr_err("upper fs missing required features.\n"); err = -EINVAL; goto out; } /* * For volatile mount, create a incompat/volatile/dirty file to keep * track of it. */ if (ofs->config.ovl_volatile) { err = ovl_create_volatile_dirty(ofs); if (err < 0) { pr_err("Failed to create volatile/dirty file.\n"); goto out; } } /* Check if upper/work fs supports file handles */ fh_type = ovl_can_decode_fh(ofs->workdir->d_sb); if (ofs->config.index && !fh_type) { ofs->config.index = false; pr_warn("upper fs does not support file handles, falling back to index=off.\n"); } ofs->nofh |= !fh_type; /* Check if upper fs has 32bit inode numbers */ if (fh_type != FILEID_INO32_GEN) ofs->xino_mode = -1; /* NFS export of r/w mount depends on index */ if (ofs->config.nfs_export && !ofs->config.index) { pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } out: mnt_drop_write(mnt); return err; } static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, const struct path *upperpath, const struct path *workpath) { int err; err = -EINVAL; if (upperpath->mnt != workpath->mnt) { pr_err("workdir and upperdir must reside under the same mount\n"); return err; } if (!ovl_workdir_ok(workpath->dentry, upperpath->dentry)) { pr_err("workdir and upperdir must be separate subtrees\n"); return err; } ofs->workbasedir = dget(workpath->dentry); if (ovl_inuse_trylock(ofs->workbasedir)) { ofs->workdir_locked = true; } else { err = ovl_report_in_use(ofs, "workdir"); if (err) return err; } err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, "workdir"); if (err) return err; return ovl_make_workdir(sb, ofs, workpath); } static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, struct ovl_entry *oe, const struct path *upperpath) { struct vfsmount *mnt = ovl_upper_mnt(ofs); struct dentry *indexdir; struct dentry *origin = ovl_lowerstack(oe)->dentry; const struct ovl_fh *fh; int err; fh = ovl_get_origin_fh(ofs, origin); if (IS_ERR(fh)) return PTR_ERR(fh); err = mnt_want_write(mnt); if (err) goto out_free_fh; /* Verify lower root is upper root origin */ err = ovl_verify_origin_fh(ofs, upperpath->dentry, fh, true); if (err) { pr_err("failed to verify upper root origin\n"); goto out; } /* index dir will act also as workdir */ iput(ofs->workdir_trap); ofs->workdir_trap = NULL; dput(ofs->workdir); ofs->workdir = NULL; indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); if (IS_ERR(indexdir)) { err = PTR_ERR(indexdir); } else if (indexdir) { ofs->workdir = indexdir; err = ovl_setup_trap(sb, indexdir, &ofs->workdir_trap, "indexdir"); if (err) goto out; /* * Verify upper root is exclusively associated with index dir. * Older kernels stored upper fh in ".overlay.origin" * xattr. If that xattr exists, verify that it is a match to * upper dir file handle. In any case, verify or set xattr * ".overlay.upper" to indicate that index may have * directory entries. */ if (ovl_check_origin_xattr(ofs, indexdir)) { err = ovl_verify_origin_xattr(ofs, indexdir, OVL_XATTR_ORIGIN, upperpath->dentry, true, false); if (err) pr_err("failed to verify index dir 'origin' xattr\n"); } err = ovl_verify_upper(ofs, indexdir, upperpath->dentry, true); if (err) pr_err("failed to verify index dir 'upper' xattr\n"); /* Cleanup bad/stale/orphan index entries */ if (!err) err = ovl_indexdir_cleanup(ofs); } if (err || !indexdir) pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); out: mnt_drop_write(mnt); out_free_fh: kfree(fh); return err; } static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) { unsigned int i; if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs)) return true; /* * We allow using single lower with null uuid for index and nfs_export * for example to support those features with single lower squashfs. * To avoid regressions in setups of overlay with re-formatted lower * squashfs, do not allow decoding origin with lower null uuid unless * user opted-in to one of the new features that require following the * lower inode of non-dir upper. */ if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid)) return false; for (i = 0; i < ofs->numfs; i++) { /* * We use uuid to associate an overlay lower file handle with a * lower layer, so we can accept lower fs with null uuid as long * as all lower layers with null uuid are on the same fs. * if we detect multiple lower fs with the same uuid, we * disable lower file handle decoding on all of them. */ if (ofs->fs[i].is_lower && uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { ofs->fs[i].bad_uuid = true; return false; } } return true; } /* Get a unique fsid for the layer */ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) { struct super_block *sb = path->mnt->mnt_sb; unsigned int i; dev_t dev; int err; bool bad_uuid = false; bool warn = false; for (i = 0; i < ofs->numfs; i++) { if (ofs->fs[i].sb == sb) return i; } if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { bad_uuid = true; if (ofs->config.xino == OVL_XINO_AUTO) { ofs->config.xino = OVL_XINO_OFF; warn = true; } if (ofs->config.index || ofs->config.nfs_export) { ofs->config.index = false; ofs->config.nfs_export = false; warn = true; } if (warn) { pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n", uuid_is_null(&sb->s_uuid) ? "null" : "conflicting", path->dentry, ovl_xino_mode(&ofs->config)); } } err = get_anon_bdev(&dev); if (err) { pr_err("failed to get anonymous bdev for lowerpath\n"); return err; } ofs->fs[ofs->numfs].sb = sb; ofs->fs[ofs->numfs].pseudo_dev = dev; ofs->fs[ofs->numfs].bad_uuid = bad_uuid; return ofs->numfs++; } /* * The fsid after the last lower fsid is used for the data layers. * It is a "null fs" with a null sb, null uuid, and no pseudo dev. */ static int ovl_get_data_fsid(struct ovl_fs *ofs) { return ofs->numfs; } static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, struct ovl_fs_context *ctx, struct ovl_layer *layers) { int err; unsigned int i; size_t nr_merged_lower; ofs->fs = kcalloc(ctx->nr + 2, sizeof(struct ovl_sb), GFP_KERNEL); if (ofs->fs == NULL) return -ENOMEM; /* * idx/fsid 0 are reserved for upper fs even with lower only overlay * and the last fsid is reserved for "null fs" of the data layers. */ ofs->numfs++; /* * All lower layers that share the same fs as upper layer, use the same * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower * only overlay to simplify ovl_fs_free(). * is_lower will be set if upper fs is shared with a lower layer. */ err = get_anon_bdev(&ofs->fs[0].pseudo_dev); if (err) { pr_err("failed to get anonymous bdev for upper fs\n"); return err; } if (ovl_upper_mnt(ofs)) { ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; ofs->fs[0].is_lower = false; } nr_merged_lower = ctx->nr - ctx->nr_data; for (i = 0; i < ctx->nr; i++) { struct ovl_fs_context_layer *l = &ctx->lower[i]; struct vfsmount *mnt; struct inode *trap; int fsid; if (i < nr_merged_lower) fsid = ovl_get_fsid(ofs, &l->path); else fsid = ovl_get_data_fsid(ofs); if (fsid < 0) return fsid; /* * Check if lower root conflicts with this overlay layers before * checking if it is in-use as upperdir/workdir of "another" * mount, because we do not bother to check in ovl_is_inuse() if * the upperdir/workdir is in fact in-use by our * upperdir/workdir. */ err = ovl_setup_trap(sb, l->path.dentry, &trap, "lowerdir"); if (err) return err; if (ovl_is_inuse(l->path.dentry)) { err = ovl_report_in_use(ofs, "lowerdir"); if (err) { iput(trap); return err; } } mnt = clone_private_mount(&l->path); err = PTR_ERR(mnt); if (IS_ERR(mnt)) { pr_err("failed to clone lowerpath\n"); iput(trap); return err; } /* * Make lower layers R/O. That way fchmod/fchown on lower file * will fail instead of modifying lower fs. */ mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; layers[ofs->numlayer].trap = trap; layers[ofs->numlayer].mnt = mnt; layers[ofs->numlayer].idx = ofs->numlayer; layers[ofs->numlayer].fsid = fsid; layers[ofs->numlayer].fs = &ofs->fs[fsid]; /* Store for printing lowerdir=... in ovl_show_options() */ ofs->config.lowerdirs[ofs->numlayer] = l->name; l->name = NULL; ofs->numlayer++; ofs->fs[fsid].is_lower = true; } /* * When all layers on same fs, overlay can use real inode numbers. * With mount option "xino=<on|auto>", mounter declares that there are * enough free high bits in underlying fs to hold the unique fsid. * If overlayfs does encounter underlying inodes using the high xino * bits reserved for fsid, it emits a warning and uses the original * inode number or a non persistent inode number allocated from a * dedicated range. */ if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) { if (ofs->config.xino == OVL_XINO_ON) pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n"); ofs->xino_mode = 0; } else if (ofs->config.xino == OVL_XINO_OFF) { ofs->xino_mode = -1; } else if (ofs->xino_mode < 0) { /* * This is a roundup of number of bits needed for encoding * fsid, where fsid 0 is reserved for upper fs (even with * lower only overlay) +1 extra bit is reserved for the non * persistent inode number range that is used for resolving * xino lower bits overflow. */ BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; } if (ofs->xino_mode > 0) { pr_info("\"xino\" feature enabled using %d upper inode bits.\n", ofs->xino_mode); } return 0; } static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, struct ovl_fs_context *ctx, struct ovl_fs *ofs, struct ovl_layer *layers) { int err; unsigned int i; size_t nr_merged_lower; struct ovl_entry *oe; struct ovl_path *lowerstack; struct ovl_fs_context_layer *l; if (!ofs->config.upperdir && ctx->nr == 1) { pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); return ERR_PTR(-EINVAL); } err = -EINVAL; for (i = 0; i < ctx->nr; i++) { l = &ctx->lower[i]; err = ovl_lower_dir(l->name, &l->path, ofs, &sb->s_stack_depth); if (err) return ERR_PTR(err); } err = -EINVAL; sb->s_stack_depth++; if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { pr_err("maximum fs stacking depth exceeded\n"); return ERR_PTR(err); } err = ovl_get_layers(sb, ofs, ctx, layers); if (err) return ERR_PTR(err); err = -ENOMEM; /* Data-only layers are not merged in root directory */ nr_merged_lower = ctx->nr - ctx->nr_data; oe = ovl_alloc_entry(nr_merged_lower); if (!oe) return ERR_PTR(err); lowerstack = ovl_lowerstack(oe); for (i = 0; i < nr_merged_lower; i++) { l = &ctx->lower[i]; lowerstack[i].dentry = dget(l->path.dentry); lowerstack[i].layer = &ofs->layers[i + 1]; } ofs->numdatalayer = ctx->nr_data; return oe; } /* * Check if this layer root is a descendant of: * - another layer of this overlayfs instance * - upper/work dir of any overlayfs instance */ static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, struct dentry *dentry, const char *name, bool is_lower) { struct dentry *next = dentry, *parent; int err = 0; if (!dentry) return 0; parent = dget_parent(next); /* Walk back ancestors to root (inclusive) looking for traps */ while (!err && parent != next) { if (is_lower && ovl_lookup_trap_inode(sb, parent)) { err = -ELOOP; pr_err("overlapping %s path\n", name); } else if (ovl_is_inuse(parent)) { err = ovl_report_in_use(ofs, name); } next = parent; parent = dget_parent(next); dput(next); } dput(parent); return err; } /* * Check if any of the layers or work dirs overlap. */ static int ovl_check_overlapping_layers(struct super_block *sb, struct ovl_fs *ofs) { int i, err; if (ovl_upper_mnt(ofs)) { err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root, "upperdir", false); if (err) return err; /* * Checking workbasedir avoids hitting ovl_is_inuse(parent) of * this instance and covers overlapping work and index dirs, * unless work or index dir have been moved since created inside * workbasedir. In that case, we already have their traps in * inode cache and we will catch that case on lookup. */ err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", false); if (err) return err; } for (i = 1; i < ofs->numlayer; i++) { err = ovl_check_layer(sb, ofs, ofs->layers[i].mnt->mnt_root, "lowerdir", true); if (err) return err; } return 0; } static struct dentry *ovl_get_root(struct super_block *sb, struct dentry *upperdentry, struct ovl_entry *oe) { struct dentry *root; struct ovl_fs *ofs = OVL_FS(sb); struct ovl_path *lowerpath = ovl_lowerstack(oe); unsigned long ino = d_inode(lowerpath->dentry)->i_ino; int fsid = lowerpath->layer->fsid; struct ovl_inode_params oip = { .upperdentry = upperdentry, .oe = oe, }; root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); if (!root) return NULL; if (upperdentry) { /* Root inode uses upper st_ino/i_ino */ ino = d_inode(upperdentry)->i_ino; fsid = 0; ovl_dentry_set_upper_alias(root); if (ovl_is_impuredir(sb, upperdentry)) ovl_set_flag(OVL_IMPURE, d_inode(root)); } /* Look for xwhiteouts marker except in the lowermost layer */ for (int i = 0; i < ovl_numlower(oe) - 1; i++, lowerpath++) { struct path path = { .mnt = lowerpath->layer->mnt, .dentry = lowerpath->dentry, }; /* overlay.opaque=x means xwhiteouts directory */ if (ovl_get_opaquedir_val(ofs, &path) == 'x') { ovl_layer_set_xwhiteouts(ofs, lowerpath->layer); ovl_dentry_set_xwhiteouts(root); } } /* Root is always merge -> can have whiteouts */ ovl_set_flag(OVL_WHITEOUTS, d_inode(root)); ovl_dentry_set_flag(OVL_E_CONNECTED, root); ovl_set_upperdata(d_inode(root)); ovl_inode_init(d_inode(root), &oip, ino, fsid); ovl_dentry_init_flags(root, upperdentry, oe, DCACHE_OP_WEAK_REVALIDATE); /* root keeps a reference of upperdentry */ dget(upperdentry); return root; } int ovl_fill_super(struct super_block *sb, struct fs_context *fc) { struct ovl_fs *ofs = sb->s_fs_info; struct ovl_fs_context *ctx = fc->fs_private; struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_layer *layers; struct cred *cred; int err; err = -EIO; if (WARN_ON(fc->user_ns != current_user_ns())) goto out_err; sb->s_d_op = &ovl_dentry_operations; err = -ENOMEM; ofs->creator_cred = cred = prepare_creds(); if (!cred) goto out_err; err = ovl_fs_params_verify(ctx, &ofs->config); if (err) goto out_err; err = -EINVAL; if (ctx->nr == 0) { if (!(fc->sb_flags & SB_SILENT)) pr_err("missing 'lowerdir'\n"); goto out_err; } err = -ENOMEM; layers = kcalloc(ctx->nr + 1, sizeof(struct ovl_layer), GFP_KERNEL); if (!layers) goto out_err; ofs->config.lowerdirs = kcalloc(ctx->nr + 1, sizeof(char *), GFP_KERNEL); if (!ofs->config.lowerdirs) { kfree(layers); goto out_err; } ofs->layers = layers; /* * Layer 0 is reserved for upper even if there's no upper. * config.lowerdirs[0] is used for storing the user provided colon * separated lowerdir string. */ ofs->config.lowerdirs[0] = ctx->lowerdir_all; ctx->lowerdir_all = NULL; ofs->numlayer = 1; sb->s_stack_depth = 0; sb->s_maxbytes = MAX_LFS_FILESIZE; atomic_long_set(&ofs->last_ino, 1); /* Assume underlying fs uses 32bit inodes unless proven otherwise */ if (ofs->config.xino != OVL_XINO_OFF) { ofs->xino_mode = BITS_PER_LONG - 32; if (!ofs->xino_mode) { pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n"); ofs->config.xino = OVL_XINO_OFF; } } /* alloc/destroy_inode needed for setting up traps in inode cache */ sb->s_op = &ovl_super_operations; if (ofs->config.upperdir) { struct super_block *upper_sb; err = -EINVAL; if (!ofs->config.workdir) { pr_err("missing 'workdir'\n"); goto out_err; } err = ovl_get_upper(sb, ofs, &layers[0], &ctx->upper); if (err) goto out_err; upper_sb = ovl_upper_mnt(ofs)->mnt_sb; if (!ovl_should_sync(ofs)) { ofs->errseq = errseq_sample(&upper_sb->s_wb_err); if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) { err = -EIO; pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n"); goto out_err; } } err = ovl_get_workdir(sb, ofs, &ctx->upper, &ctx->work); if (err) goto out_err; if (!ofs->workdir) sb->s_flags |= SB_RDONLY; sb->s_stack_depth = upper_sb->s_stack_depth; sb->s_time_gran = upper_sb->s_time_gran; } oe = ovl_get_lowerstack(sb, ctx, ofs, layers); err = PTR_ERR(oe); if (IS_ERR(oe)) goto out_err; /* If the upper fs is nonexistent, we mark overlayfs r/o too */ if (!ovl_upper_mnt(ofs)) sb->s_flags |= SB_RDONLY; if (!ovl_origin_uuid(ofs) && ofs->numfs > 1) { pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=null.\n"); ofs->config.uuid = OVL_UUID_NULL; } else if (ovl_has_fsid(ofs) && ovl_upper_mnt(ofs)) { /* Use per instance persistent uuid/fsid */ ovl_init_uuid_xattr(sb, ofs, &ctx->upper); } if (!ovl_force_readonly(ofs) && ofs->config.index) { err = ovl_get_indexdir(sb, ofs, oe, &ctx->upper); if (err) goto out_free_oe; /* Force r/o mount with no index dir */ if (!ofs->workdir) sb->s_flags |= SB_RDONLY; } err = ovl_check_overlapping_layers(sb, ofs); if (err) goto out_free_oe; /* Show index=off in /proc/mounts for forced r/o mount */ if (!ofs->workdir) { ofs->config.index = false; if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) { pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } } if (ofs->config.metacopy && ofs->config.nfs_export) { pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } /* * Support encoding decodable file handles with nfs_export=on * and encoding non-decodable file handles with nfs_export=off * if all layers support file handles. */ if (ofs->config.nfs_export) sb->s_export_op = &ovl_export_operations; else if (!ofs->nofh) sb->s_export_op = &ovl_export_fid_operations; /* Never override disk quota limits or use reserved space */ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_xattr = ovl_xattr_handlers(ofs); sb->s_fs_info = ofs; #ifdef CONFIG_FS_POSIX_ACL sb->s_flags |= SB_POSIXACL; #endif sb->s_iflags |= SB_I_SKIP_SYNC; /* * Ensure that umask handling is done by the filesystems used * for the the upper layer instead of overlayfs as that would * lead to unexpected results. */ sb->s_iflags |= SB_I_NOUMASK; sb->s_iflags |= SB_I_EVM_HMAC_UNSUPPORTED; err = -ENOMEM; root_dentry = ovl_get_root(sb, ctx->upper.dentry, oe); if (!root_dentry) goto out_free_oe; sb->s_root = root_dentry; return 0; out_free_oe: ovl_free_entry(oe); out_err: ovl_free_fs(ofs); sb->s_fs_info = NULL; return err; } struct file_system_type ovl_fs_type = { .owner = THIS_MODULE, .name = "overlay", .init_fs_context = ovl_init_fs_context, .parameters = ovl_parameter_spec, .fs_flags = FS_USERNS_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_ACCOUNT), ovl_inode_init_once); if (ovl_inode_cachep == NULL) return -ENOMEM; err = register_filesystem(&ovl_fs_type); if (!err) return 0; 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);
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