| /* |
| * |
| * Copyright (C) 2011 Novell Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 as published by |
| * the Free Software Foundation. |
| */ |
| |
| #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 "overlayfs.h" |
| |
| MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); |
| MODULE_DESCRIPTION("Overlay filesystem"); |
| MODULE_LICENSE("GPL"); |
| |
| |
| struct ovl_dir_cache; |
| |
| #define OVL_MAX_STACK 500 |
| |
| static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); |
| module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); |
| MODULE_PARM_DESC(ovl_redirect_dir_def, |
| "Default to on or off for the redirect_dir feature"); |
| |
| static bool ovl_redirect_always_follow = |
| IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); |
| module_param_named(redirect_always_follow, ovl_redirect_always_follow, |
| bool, 0644); |
| MODULE_PARM_DESC(ovl_redirect_always_follow, |
| "Follow redirects even if redirect_dir feature is turned off"); |
| |
| static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); |
| module_param_named(index, ovl_index_def, bool, 0644); |
| MODULE_PARM_DESC(ovl_index_def, |
| "Default to on or off for the inodes index feature"); |
| |
| static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); |
| module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); |
| MODULE_PARM_DESC(ovl_nfs_export_def, |
| "Default to on or off for the NFS export feature"); |
| |
| static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); |
| module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); |
| MODULE_PARM_DESC(ovl_xino_auto_def, |
| "Auto enable xino feature"); |
| |
| static void ovl_entry_stack_free(struct ovl_entry *oe) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < oe->numlower; i++) |
| dput(oe->lowerstack[i].dentry); |
| } |
| |
| static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY); |
| module_param_named(metacopy, ovl_metacopy_def, bool, 0644); |
| MODULE_PARM_DESC(ovl_metacopy_def, |
| "Default to on or off for the metadata only copy up feature"); |
| |
| static void ovl_dentry_release(struct dentry *dentry) |
| { |
| struct ovl_entry *oe = dentry->d_fsdata; |
| |
| if (oe) { |
| ovl_entry_stack_free(oe); |
| kfree_rcu(oe, rcu); |
| } |
| } |
| |
| static struct dentry *ovl_d_real(struct dentry *dentry, |
| const struct inode *inode) |
| { |
| struct dentry *real = NULL, *lower; |
| |
| /* It's an overlay file */ |
| if (inode && d_inode(dentry) == inode) |
| return dentry; |
| |
| if (!d_is_reg(dentry)) { |
| if (!inode || inode == d_inode(dentry)) |
| return dentry; |
| goto bug; |
| } |
| |
| real = ovl_dentry_upper(dentry); |
| if (real && (inode == d_inode(real))) |
| return real; |
| |
| if (real && !inode && ovl_has_upperdata(d_inode(dentry))) |
| return real; |
| |
| lower = ovl_dentry_lowerdata(dentry); |
| if (!lower) |
| goto bug; |
| real = lower; |
| |
| /* Handle recursion */ |
| real = d_real(real, inode); |
| |
| if (!inode || inode == d_inode(real)) |
| return real; |
| bug: |
| WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n", |
| __func__, dentry, inode ? inode->i_sb->s_id : "NULL", |
| inode ? inode->i_ino : 0, real, |
| real && d_inode(real) ? d_inode(real)->i_ino : 0); |
| return dentry; |
| } |
| |
| static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
| { |
| struct ovl_entry *oe = dentry->d_fsdata; |
| unsigned int i; |
| int ret = 1; |
| |
| for (i = 0; i < oe->numlower; i++) { |
| struct dentry *d = oe->lowerstack[i].dentry; |
| |
| if (d->d_flags & DCACHE_OP_REVALIDATE) { |
| ret = d->d_op->d_revalidate(d, flags); |
| if (ret < 0) |
| return ret; |
| if (!ret) { |
| if (!(flags & LOOKUP_RCU)) |
| d_invalidate(d); |
| return -ESTALE; |
| } |
| } |
| } |
| return 1; |
| } |
| |
| static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) |
| { |
| struct ovl_entry *oe = dentry->d_fsdata; |
| unsigned int i; |
| int ret = 1; |
| |
| for (i = 0; i < oe->numlower; i++) { |
| struct dentry *d = oe->lowerstack[i].dentry; |
| |
| if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { |
| ret = d->d_op->d_weak_revalidate(d, flags); |
| if (ret <= 0) |
| break; |
| } |
| } |
| return ret; |
| } |
| |
| static const struct dentry_operations ovl_dentry_operations = { |
| .d_release = ovl_dentry_release, |
| .d_real = ovl_d_real, |
| }; |
| |
| static const struct dentry_operations ovl_reval_dentry_operations = { |
| .d_release = ovl_dentry_release, |
| .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 = kmem_cache_alloc(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->lower = NULL; |
| oi->lowerdata = NULL; |
| mutex_init(&oi->lock); |
| |
| return &oi->vfs_inode; |
| } |
| |
| static void ovl_i_callback(struct rcu_head *head) |
| { |
| struct inode *inode = container_of(head, struct inode, i_rcu); |
| |
| kmem_cache_free(ovl_inode_cachep, OVL_I(inode)); |
| } |
| |
| static void ovl_destroy_inode(struct inode *inode) |
| { |
| struct ovl_inode *oi = OVL_I(inode); |
| |
| dput(oi->__upperdentry); |
| iput(oi->lower); |
| if (S_ISDIR(inode->i_mode)) |
| ovl_dir_cache_free(inode); |
| else |
| iput(oi->lowerdata); |
| kfree(oi->redirect); |
| mutex_destroy(&oi->lock); |
| |
| call_rcu(&inode->i_rcu, ovl_i_callback); |
| } |
| |
| static void ovl_free_fs(struct ovl_fs *ofs) |
| { |
| unsigned i; |
| |
| iput(ofs->workbasedir_trap); |
| iput(ofs->indexdir_trap); |
| iput(ofs->workdir_trap); |
| iput(ofs->upperdir_trap); |
| dput(ofs->indexdir); |
| dput(ofs->workdir); |
| if (ofs->workdir_locked) |
| ovl_inuse_unlock(ofs->workbasedir); |
| dput(ofs->workbasedir); |
| if (ofs->upperdir_locked) |
| ovl_inuse_unlock(ofs->upper_mnt->mnt_root); |
| mntput(ofs->upper_mnt); |
| for (i = 0; i < ofs->numlower; i++) { |
| iput(ofs->lower_layers[i].trap); |
| mntput(ofs->lower_layers[i].mnt); |
| } |
| for (i = 0; i < ofs->numlowerfs; i++) |
| free_anon_bdev(ofs->lower_fs[i].pseudo_dev); |
| kfree(ofs->lower_layers); |
| kfree(ofs->lower_fs); |
| |
| kfree(ofs->config.lowerdir); |
| kfree(ofs->config.upperdir); |
| kfree(ofs->config.workdir); |
| kfree(ofs->config.redirect_mode); |
| if (ofs->creator_cred) |
| put_cred(ofs->creator_cred); |
| kfree(ofs); |
| } |
| |
| static void ovl_put_super(struct super_block *sb) |
| { |
| struct ovl_fs *ofs = sb->s_fs_info; |
| |
| 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 = sb->s_fs_info; |
| struct super_block *upper_sb; |
| int ret; |
| |
| if (!ofs->upper_mnt) |
| return 0; |
| |
| /* |
| * If this is a sync(2) call or an emergency sync, all the super blocks |
| * will be iterated, including upper_sb, so no need to do anything. |
| * |
| * 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 = ofs->upper_mnt->mnt_sb; |
| |
| down_read(&upper_sb->s_umount); |
| ret = sync_filesystem(upper_sb); |
| up_read(&upper_sb->s_umount); |
| |
| return ret; |
| } |
| |
| /** |
| * ovl_statfs |
| * @sb: The overlayfs super block |
| * @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 ovl_fs *ofs = dentry->d_sb->s_fs_info; |
| struct dentry *root_dentry = dentry->d_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; |
| } |
| |
| return err; |
| } |
| |
| /* Will this overlay be forced to mount/remount ro? */ |
| static bool ovl_force_readonly(struct ovl_fs *ofs) |
| { |
| return (!ofs->upper_mnt || !ofs->workdir); |
| } |
| |
| static const char *ovl_redirect_mode_def(void) |
| { |
| return ovl_redirect_dir_def ? "on" : "off"; |
| } |
| |
| enum { |
| OVL_XINO_OFF, |
| OVL_XINO_AUTO, |
| OVL_XINO_ON, |
| }; |
| |
| static const char * const ovl_xino_str[] = { |
| "off", |
| "auto", |
| "on", |
| }; |
| |
| static inline int ovl_xino_def(void) |
| { |
| return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; |
| } |
| |
| /** |
| * ovl_show_options |
| * |
| * Prints the mount options for a given superblock. |
| * Returns zero; does not fail. |
| */ |
| static int ovl_show_options(struct seq_file *m, struct dentry *dentry) |
| { |
| struct super_block *sb = dentry->d_sb; |
| struct ovl_fs *ofs = sb->s_fs_info; |
| |
| seq_show_option(m, "lowerdir", ofs->config.lowerdir); |
| if (ofs->config.upperdir) { |
| seq_show_option(m, "upperdir", ofs->config.upperdir); |
| seq_show_option(m, "workdir", ofs->config.workdir); |
| } |
| if (ofs->config.default_permissions) |
| seq_puts(m, ",default_permissions"); |
| if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) |
| seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); |
| if (ofs->config.index != ovl_index_def) |
| seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); |
| if (ofs->config.nfs_export != ovl_nfs_export_def) |
| seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? |
| "on" : "off"); |
| if (ofs->config.xino != ovl_xino_def()) |
| seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]); |
| if (ofs->config.metacopy != ovl_metacopy_def) |
| seq_printf(m, ",metacopy=%s", |
| ofs->config.metacopy ? "on" : "off"); |
| return 0; |
| } |
| |
| static int ovl_remount(struct super_block *sb, int *flags, char *data) |
| { |
| struct ovl_fs *ofs = sb->s_fs_info; |
| |
| if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) |
| return -EROFS; |
| |
| return 0; |
| } |
| |
| static const struct super_operations ovl_super_operations = { |
| .alloc_inode = ovl_alloc_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, |
| .remount_fs = ovl_remount, |
| }; |
| |
| enum { |
| OPT_LOWERDIR, |
| OPT_UPPERDIR, |
| OPT_WORKDIR, |
| OPT_DEFAULT_PERMISSIONS, |
| OPT_REDIRECT_DIR, |
| OPT_INDEX_ON, |
| OPT_INDEX_OFF, |
| OPT_NFS_EXPORT_ON, |
| OPT_NFS_EXPORT_OFF, |
| OPT_XINO_ON, |
| OPT_XINO_OFF, |
| OPT_XINO_AUTO, |
| OPT_METACOPY_ON, |
| OPT_METACOPY_OFF, |
| OPT_ERR, |
| }; |
| |
| static const match_table_t ovl_tokens = { |
| {OPT_LOWERDIR, "lowerdir=%s"}, |
| {OPT_UPPERDIR, "upperdir=%s"}, |
| {OPT_WORKDIR, "workdir=%s"}, |
| {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
| {OPT_REDIRECT_DIR, "redirect_dir=%s"}, |
| {OPT_INDEX_ON, "index=on"}, |
| {OPT_INDEX_OFF, "index=off"}, |
| {OPT_NFS_EXPORT_ON, "nfs_export=on"}, |
| {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, |
| {OPT_XINO_ON, "xino=on"}, |
| {OPT_XINO_OFF, "xino=off"}, |
| {OPT_XINO_AUTO, "xino=auto"}, |
| {OPT_METACOPY_ON, "metacopy=on"}, |
| {OPT_METACOPY_OFF, "metacopy=off"}, |
| {OPT_ERR, NULL} |
| }; |
| |
| static char *ovl_next_opt(char **s) |
| { |
| char *sbegin = *s; |
| char *p; |
| |
| if (sbegin == NULL) |
| return NULL; |
| |
| for (p = sbegin; *p; p++) { |
| if (*p == '\\') { |
| p++; |
| if (!*p) |
| break; |
| } else if (*p == ',') { |
| *p = '\0'; |
| *s = p + 1; |
| return sbegin; |
| } |
| } |
| *s = NULL; |
| return sbegin; |
| } |
| |
| static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) |
| { |
| if (strcmp(mode, "on") == 0) { |
| config->redirect_dir = true; |
| /* |
| * Does not make sense to have redirect creation without |
| * redirect following. |
| */ |
| config->redirect_follow = true; |
| } else if (strcmp(mode, "follow") == 0) { |
| config->redirect_follow = true; |
| } else if (strcmp(mode, "off") == 0) { |
| if (ovl_redirect_always_follow) |
| config->redirect_follow = true; |
| } else if (strcmp(mode, "nofollow") != 0) { |
| pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n", |
| mode); |
| return -EINVAL; |
| } |
| |
| return 0; |
| } |
| |
| static int ovl_parse_opt(char *opt, struct ovl_config *config) |
| { |
| char *p; |
| int err; |
| bool metacopy_opt = false, redirect_opt = false; |
| |
| config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); |
| if (!config->redirect_mode) |
| return -ENOMEM; |
| |
| while ((p = ovl_next_opt(&opt)) != NULL) { |
| int token; |
| substring_t args[MAX_OPT_ARGS]; |
| |
| if (!*p) |
| continue; |
| |
| token = match_token(p, ovl_tokens, args); |
| switch (token) { |
| case OPT_UPPERDIR: |
| kfree(config->upperdir); |
| config->upperdir = match_strdup(&args[0]); |
| if (!config->upperdir) |
| return -ENOMEM; |
| break; |
| |
| case OPT_LOWERDIR: |
| kfree(config->lowerdir); |
| config->lowerdir = match_strdup(&args[0]); |
| if (!config->lowerdir) |
| return -ENOMEM; |
| break; |
| |
| case OPT_WORKDIR: |
| kfree(config->workdir); |
| config->workdir = match_strdup(&args[0]); |
| if (!config->workdir) |
| return -ENOMEM; |
| break; |
| |
| case OPT_DEFAULT_PERMISSIONS: |
| config->default_permissions = true; |
| break; |
| |
| case OPT_REDIRECT_DIR: |
| kfree(config->redirect_mode); |
| config->redirect_mode = match_strdup(&args[0]); |
| if (!config->redirect_mode) |
| return -ENOMEM; |
| redirect_opt = true; |
| break; |
| |
| case OPT_INDEX_ON: |
| config->index = true; |
| break; |
| |
| case OPT_INDEX_OFF: |
| config->index = false; |
| break; |
| |
| case OPT_NFS_EXPORT_ON: |
| config->nfs_export = true; |
| break; |
| |
| case OPT_NFS_EXPORT_OFF: |
| config->nfs_export = false; |
| break; |
| |
| case OPT_XINO_ON: |
| config->xino = OVL_XINO_ON; |
| break; |
| |
| case OPT_XINO_OFF: |
| config->xino = OVL_XINO_OFF; |
| break; |
| |
| case OPT_XINO_AUTO: |
| config->xino = OVL_XINO_AUTO; |
| break; |
| |
| case OPT_METACOPY_ON: |
| config->metacopy = true; |
| metacopy_opt = true; |
| break; |
| |
| case OPT_METACOPY_OFF: |
| config->metacopy = false; |
| break; |
| |
| default: |
| pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
| return -EINVAL; |
| } |
| } |
| |
| /* Workdir is useless in non-upper mount */ |
| if (!config->upperdir && config->workdir) { |
| pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", |
| config->workdir); |
| kfree(config->workdir); |
| config->workdir = NULL; |
| } |
| |
| err = ovl_parse_redirect_mode(config, config->redirect_mode); |
| if (err) |
| return err; |
| |
| /* |
| * This is to make the logic below simpler. It doesn't make any other |
| * difference, since config->redirect_dir is only used for upper. |
| */ |
| if (!config->upperdir && config->redirect_follow) |
| config->redirect_dir = true; |
| |
| /* Resolve metacopy -> redirect_dir dependency */ |
| if (config->metacopy && !config->redirect_dir) { |
| if (metacopy_opt && redirect_opt) { |
| pr_err("overlayfs: conflicting options: metacopy=on,redirect_dir=%s\n", |
| config->redirect_mode); |
| return -EINVAL; |
| } |
| if (redirect_opt) { |
| /* |
| * There was an explicit redirect_dir=... that resulted |
| * in this conflict. |
| */ |
| pr_info("overlayfs: disabling metacopy due to redirect_dir=%s\n", |
| config->redirect_mode); |
| config->metacopy = false; |
| } else { |
| /* Automatically enable redirect otherwise. */ |
| config->redirect_follow = config->redirect_dir = true; |
| } |
| } |
| |
| return 0; |
| } |
| |
| #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 = ofs->upper_mnt; |
| struct dentry *work; |
| int err; |
| bool retried = false; |
| bool locked = false; |
| |
| inode_lock_nested(dir, I_MUTEX_PARENT); |
| locked = true; |
| |
| retry: |
| work = lookup_one_len(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; |
| ovl_workdir_cleanup(dir, mnt, work, 0); |
| dput(work); |
| goto retry; |
| } |
| |
| err = ovl_mkdir_real(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 = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT); |
| if (err && err != -ENODATA && err != -EOPNOTSUPP) |
| goto out_dput; |
| |
| err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS); |
| if (err && err != -ENODATA && err != -EOPNOTSUPP) |
| goto out_dput; |
| |
| /* Clear any inherited mode bits */ |
| inode_lock(work->d_inode); |
| err = notify_change(work, &attr, NULL); |
| inode_unlock(work->d_inode); |
| if (err) |
| goto out_dput; |
| } else { |
| err = PTR_ERR(work); |
| goto out_err; |
| } |
| out_unlock: |
| if (locked) |
| inode_unlock(dir); |
| |
| return work; |
| |
| out_dput: |
| dput(work); |
| out_err: |
| pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
| ofs->config.workdir, name, -err); |
| work = NULL; |
| goto out_unlock; |
| } |
| |
| static void ovl_unescape(char *s) |
| { |
| char *d = s; |
| |
| for (;; s++, d++) { |
| if (*s == '\\') |
| s++; |
| *d = *s; |
| if (!*s) |
| break; |
| } |
| } |
| |
| static int ovl_mount_dir_noesc(const char *name, struct path *path) |
| { |
| int err = -EINVAL; |
| |
| if (!*name) { |
| pr_err("overlayfs: empty lowerdir\n"); |
| goto out; |
| } |
| err = kern_path(name, LOOKUP_FOLLOW, path); |
| if (err) { |
| pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); |
| goto out; |
| } |
| err = -EINVAL; |
| if (ovl_dentry_weird(path->dentry)) { |
| pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
| goto out_put; |
| } |
| if (!d_is_dir(path->dentry)) { |
| pr_err("overlayfs: '%s' not a directory\n", name); |
| goto out_put; |
| } |
| return 0; |
| |
| out_put: |
| path_put_init(path); |
| out: |
| return err; |
| } |
| |
| static int ovl_mount_dir(const char *name, struct path *path) |
| { |
| int err = -ENOMEM; |
| char *tmp = kstrdup(name, GFP_KERNEL); |
| |
| if (tmp) { |
| ovl_unescape(tmp); |
| err = ovl_mount_dir_noesc(tmp, path); |
| |
| if (!err) |
| if (ovl_dentry_remote(path->dentry)) { |
| pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", |
| tmp); |
| path_put_init(path); |
| err = -EINVAL; |
| } |
| kfree(tmp); |
| } |
| return err; |
| } |
| |
| static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, |
| const char *name) |
| { |
| struct kstatfs statfs; |
| int err = vfs_statfs(path, &statfs); |
| |
| if (err) |
| pr_err("overlayfs: statfs failed on '%s'\n", name); |
| else |
| ofs->namelen = max(ofs->namelen, statfs.f_namelen); |
| |
| return err; |
| } |
| |
| static int ovl_lower_dir(const char *name, struct path *path, |
| struct ovl_fs *ofs, int *stack_depth, bool *remote) |
| { |
| int fh_type; |
| int err; |
| |
| err = ovl_mount_dir_noesc(name, path); |
| if (err) |
| goto out; |
| |
| err = ovl_check_namelen(path, ofs, name); |
| if (err) |
| goto out_put; |
| |
| *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); |
| |
| if (ovl_dentry_remote(path->dentry)) |
| *remote = true; |
| |
| /* |
| * The inodes index feature 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("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", |
| name); |
| } |
| |
| /* Check if lower fs has 32bit inode numbers */ |
| if (fh_type != FILEID_INO32_GEN) |
| ofs->xino_bits = 0; |
| |
| return 0; |
| |
| out_put: |
| path_put_init(path); |
| out: |
| return err; |
| } |
| |
| /* Workdir should not be subdir of upperdir and vice versa */ |
| static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) |
| { |
| bool ok = false; |
| |
| if (workdir != upperdir) { |
| ok = (lock_rename(workdir, upperdir) == NULL); |
| unlock_rename(workdir, upperdir); |
| } |
| return ok; |
| } |
| |
| static unsigned int ovl_split_lowerdirs(char *str) |
| { |
| unsigned int ctr = 1; |
| char *s, *d; |
| |
| for (s = d = str;; s++, d++) { |
| if (*s == '\\') { |
| s++; |
| } else if (*s == ':') { |
| *d = '\0'; |
| ctr++; |
| continue; |
| } |
| *d = *s; |
| if (!*s) |
| break; |
| } |
| return ctr; |
| } |
| |
| static int __maybe_unused |
| ovl_posix_acl_xattr_get(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, void *buffer, size_t size) |
| { |
| return ovl_xattr_get(dentry, inode, handler->name, buffer, size); |
| } |
| |
| static int __maybe_unused |
| ovl_posix_acl_xattr_set(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, const void *value, |
| size_t size, int flags) |
| { |
| struct dentry *workdir = ovl_workdir(dentry); |
| struct inode *realinode = ovl_inode_real(inode); |
| struct posix_acl *acl = NULL; |
| int err; |
| |
| /* Check that everything is OK before copy-up */ |
| if (value) { |
| acl = posix_acl_from_xattr(&init_user_ns, value, size); |
| if (IS_ERR(acl)) |
| return PTR_ERR(acl); |
| } |
| err = -EOPNOTSUPP; |
| if (!IS_POSIXACL(d_inode(workdir))) |
| goto out_acl_release; |
| if (!realinode->i_op->set_acl) |
| goto out_acl_release; |
| if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { |
| err = acl ? -EACCES : 0; |
| goto out_acl_release; |
| } |
| err = -EPERM; |
| if (!inode_owner_or_capable(inode)) |
| goto out_acl_release; |
| |
| posix_acl_release(acl); |
| |
| /* |
| * Check if sgid bit needs to be cleared (actual setacl operation will |
| * be done with mounter's capabilities and so that won't do it for us). |
| */ |
| if (unlikely(inode->i_mode & S_ISGID) && |
| handler->flags == ACL_TYPE_ACCESS && |
| !in_group_p(inode->i_gid) && |
| !capable_wrt_inode_uidgid(inode, CAP_FSETID)) { |
| struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; |
| |
| err = ovl_setattr(dentry, &iattr); |
| if (err) |
| return err; |
| } |
| |
| err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); |
| if (!err) |
| ovl_copyattr(ovl_inode_real(inode), inode); |
| |
| return err; |
| |
| out_acl_release: |
| posix_acl_release(acl); |
| return err; |
| } |
| |
| static int ovl_own_xattr_get(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, void *buffer, size_t size) |
| { |
| return -EOPNOTSUPP; |
| } |
| |
| static int ovl_own_xattr_set(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, const void *value, |
| size_t size, int flags) |
| { |
| return -EOPNOTSUPP; |
| } |
| |
| static int ovl_other_xattr_get(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, void *buffer, size_t size) |
| { |
| return ovl_xattr_get(dentry, inode, name, buffer, size); |
| } |
| |
| static int ovl_other_xattr_set(const struct xattr_handler *handler, |
| struct dentry *dentry, struct inode *inode, |
| const char *name, const void *value, |
| size_t size, int flags) |
| { |
| return ovl_xattr_set(dentry, inode, name, value, size, flags); |
| } |
| |
| static const struct xattr_handler __maybe_unused |
| ovl_posix_acl_access_xattr_handler = { |
| .name = XATTR_NAME_POSIX_ACL_ACCESS, |
| .flags = ACL_TYPE_ACCESS, |
| .get = ovl_posix_acl_xattr_get, |
| .set = ovl_posix_acl_xattr_set, |
| }; |
| |
| static const struct xattr_handler __maybe_unused |
| ovl_posix_acl_default_xattr_handler = { |
| .name = XATTR_NAME_POSIX_ACL_DEFAULT, |
| .flags = ACL_TYPE_DEFAULT, |
| .get = ovl_posix_acl_xattr_get, |
| .set = ovl_posix_acl_xattr_set, |
| }; |
| |
| static const struct xattr_handler ovl_own_xattr_handler = { |
| .prefix = OVL_XATTR_PREFIX, |
| .get = ovl_own_xattr_get, |
| .set = ovl_own_xattr_set, |
| }; |
| |
| static const struct xattr_handler ovl_other_xattr_handler = { |
| .prefix = "", /* catch all */ |
| .get = ovl_other_xattr_get, |
| .set = ovl_other_xattr_set, |
| }; |
| |
| static const struct xattr_handler *ovl_xattr_handlers[] = { |
| #ifdef CONFIG_FS_POSIX_ACL |
| &ovl_posix_acl_access_xattr_handler, |
| &ovl_posix_acl_default_xattr_handler, |
| #endif |
| &ovl_own_xattr_handler, |
| &ovl_other_xattr_handler, |
| NULL |
| }; |
| |
| static int ovl_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("overlayfs: 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("overlayfs: %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("overlayfs: %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 path *upperpath) |
| { |
| struct vfsmount *upper_mnt; |
| int err; |
| |
| err = ovl_mount_dir(ofs->config.upperdir, upperpath); |
| if (err) |
| goto out; |
| |
| /* Upper fs should not be r/o */ |
| if (sb_rdonly(upperpath->mnt->mnt_sb)) { |
| pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); |
| err = -EINVAL; |
| goto out; |
| } |
| |
| err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); |
| if (err) |
| goto out; |
| |
| err = ovl_setup_trap(sb, upperpath->dentry, &ofs->upperdir_trap, |
| "upperdir"); |
| if (err) |
| goto out; |
| |
| upper_mnt = clone_private_mount(upperpath); |
| err = PTR_ERR(upper_mnt); |
| if (IS_ERR(upper_mnt)) { |
| pr_err("overlayfs: failed to clone upperpath\n"); |
| goto out; |
| } |
| |
| /* Don't inherit atime flags */ |
| upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); |
| ofs->upper_mnt = upper_mnt; |
| |
| if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) { |
| ofs->upperdir_locked = true; |
| } else { |
| err = ovl_report_in_use(ofs, "upperdir"); |
| if (err) |
| goto out; |
| } |
| |
| err = 0; |
| out: |
| return err; |
| } |
| |
| static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, |
| struct path *workpath) |
| { |
| struct vfsmount *mnt = ofs->upper_mnt; |
| struct dentry *temp; |
| int fh_type; |
| int err; |
| |
| err = mnt_want_write(mnt); |
| if (err) |
| return err; |
| |
| ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); |
| if (!ofs->workdir) |
| goto out; |
| |
| 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; |
| |
| /* |
| * We allowed this configuration and don't want to break users over |
| * kernel upgrade. So warn instead of erroring out. |
| */ |
| if (!err) |
| pr_warn("overlayfs: upper fs needs to support d_type.\n"); |
| |
| /* Check if upper/work fs supports O_TMPFILE */ |
| temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0); |
| ofs->tmpfile = !IS_ERR(temp); |
| if (ofs->tmpfile) |
| dput(temp); |
| else |
| pr_warn("overlayfs: upper fs does not support tmpfile.\n"); |
| |
| /* |
| * Check if upper/work fs supports trusted.overlay.* xattr |
| */ |
| err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0); |
| if (err) { |
| ofs->noxattr = true; |
| ofs->config.index = false; |
| ofs->config.metacopy = false; |
| pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n"); |
| err = 0; |
| } else { |
| vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE); |
| } |
| |
| /* 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("overlayfs: upper fs does not support file handles, falling back to index=off.\n"); |
| } |
| |
| /* Check if upper fs has 32bit inode numbers */ |
| if (fh_type != FILEID_INO32_GEN) |
| ofs->xino_bits = 0; |
| |
| /* NFS export of r/w mount depends on index */ |
| if (ofs->config.nfs_export && !ofs->config.index) { |
| pr_warn("overlayfs: 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, |
| struct path *upperpath) |
| { |
| int err; |
| struct path workpath = { }; |
| |
| err = ovl_mount_dir(ofs->config.workdir, &workpath); |
| if (err) |
| goto out; |
| |
| err = -EINVAL; |
| if (upperpath->mnt != workpath.mnt) { |
| pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); |
| goto out; |
| } |
| if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { |
| pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); |
| goto out; |
| } |
| |
| 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) |
| goto out; |
| } |
| |
| err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, |
| "workdir"); |
| if (err) |
| goto out; |
| |
| err = ovl_make_workdir(sb, ofs, &workpath); |
| |
| out: |
| path_put(&workpath); |
| |
| return err; |
| } |
| |
| static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, |
| struct ovl_entry *oe, struct path *upperpath) |
| { |
| struct vfsmount *mnt = ofs->upper_mnt; |
| int err; |
| |
| err = mnt_want_write(mnt); |
| if (err) |
| return err; |
| |
| /* Verify lower root is upper root origin */ |
| err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry, |
| true); |
| if (err) { |
| pr_err("overlayfs: failed to verify upper root origin\n"); |
| goto out; |
| } |
| |
| ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); |
| if (ofs->indexdir) { |
| err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap, |
| "indexdir"); |
| if (err) |
| goto out; |
| |
| /* |
| * Verify upper root is exclusively associated with index dir. |
| * Older kernels stored upper fh in "trusted.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 |
| * "trusted.overlay.upper" to indicate that index may have |
| * directory entries. |
| */ |
| if (ovl_check_origin_xattr(ofs->indexdir)) { |
| err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN, |
| upperpath->dentry, true, false); |
| if (err) |
| pr_err("overlayfs: failed to verify index dir 'origin' xattr\n"); |
| } |
| err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true); |
| if (err) |
| pr_err("overlayfs: failed to verify index dir 'upper' xattr\n"); |
| |
| /* Cleanup bad/stale/orphan index entries */ |
| if (!err) |
| err = ovl_indexdir_cleanup(ofs); |
| } |
| if (err || !ofs->indexdir) |
| pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); |
| |
| out: |
| mnt_drop_write(mnt); |
| return err; |
| } |
| |
| /* Get a unique fsid for the layer */ |
| static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb) |
| { |
| unsigned int i; |
| dev_t dev; |
| int err; |
| |
| /* fsid 0 is reserved for upper fs even with non upper overlay */ |
| if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb) |
| return 0; |
| |
| for (i = 0; i < ofs->numlowerfs; i++) { |
| if (ofs->lower_fs[i].sb == sb) |
| return i + 1; |
| } |
| |
| err = get_anon_bdev(&dev); |
| if (err) { |
| pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n"); |
| return err; |
| } |
| |
| ofs->lower_fs[ofs->numlowerfs].sb = sb; |
| ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev; |
| ofs->numlowerfs++; |
| |
| return ofs->numlowerfs; |
| } |
| |
| static int ovl_get_lower_layers(struct super_block *sb, struct ovl_fs *ofs, |
| struct path *stack, unsigned int numlower) |
| { |
| int err; |
| unsigned int i; |
| |
| err = -ENOMEM; |
| ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer), |
| GFP_KERNEL); |
| if (ofs->lower_layers == NULL) |
| goto out; |
| |
| ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb), |
| GFP_KERNEL); |
| if (ofs->lower_fs == NULL) |
| goto out; |
| |
| for (i = 0; i < numlower; i++) { |
| struct vfsmount *mnt; |
| struct inode *trap; |
| int fsid; |
| |
| err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb); |
| if (err < 0) |
| goto out; |
| |
| /* |
| * 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, stack[i].dentry, &trap, "lowerdir"); |
| if (err) |
| goto out; |
| |
| if (ovl_is_inuse(stack[i].dentry)) { |
| err = ovl_report_in_use(ofs, "lowerdir"); |
| if (err) { |
| iput(trap); |
| goto out; |
| } |
| } |
| |
| mnt = clone_private_mount(&stack[i]); |
| err = PTR_ERR(mnt); |
| if (IS_ERR(mnt)) { |
| pr_err("overlayfs: failed to clone lowerpath\n"); |
| iput(trap); |
| goto out; |
| } |
| |
| /* |
| * 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; |
| |
| ofs->lower_layers[ofs->numlower].trap = trap; |
| ofs->lower_layers[ofs->numlower].mnt = mnt; |
| ofs->lower_layers[ofs->numlower].idx = i + 1; |
| ofs->lower_layers[ofs->numlower].fsid = fsid; |
| if (fsid) { |
| ofs->lower_layers[ofs->numlower].fs = |
| &ofs->lower_fs[fsid - 1]; |
| } |
| ofs->numlower++; |
| } |
| |
| /* |
| * When all layers on same fs, overlay can use real inode numbers. |
| * With mount option "xino=on", 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. |
| */ |
| if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) { |
| ofs->xino_bits = 0; |
| ofs->config.xino = OVL_XINO_OFF; |
| } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) { |
| /* |
| * This is a roundup of number of bits needed for numlowerfs+1 |
| * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for |
| * upper fs even with non upper overlay. |
| */ |
| BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31); |
| ofs->xino_bits = ilog2(ofs->numlowerfs) + 1; |
| } |
| |
| if (ofs->xino_bits) { |
| pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n", |
| ofs->xino_bits); |
| } |
| |
| err = 0; |
| out: |
| return err; |
| } |
| |
| static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, |
| struct ovl_fs *ofs) |
| { |
| int err; |
| char *lowertmp, *lower; |
| struct path *stack = NULL; |
| unsigned int stacklen, numlower = 0, i; |
| bool remote = false; |
| struct ovl_entry *oe; |
| |
| err = -ENOMEM; |
| lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL); |
| if (!lowertmp) |
| goto out_err; |
| |
| err = -EINVAL; |
| stacklen = ovl_split_lowerdirs(lowertmp); |
| if (stacklen > OVL_MAX_STACK) { |
| pr_err("overlayfs: too many lower directories, limit is %d\n", |
| OVL_MAX_STACK); |
| goto out_err; |
| } else if (!ofs->config.upperdir && stacklen == 1) { |
| pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); |
| goto out_err; |
| } else if (!ofs->config.upperdir && ofs->config.nfs_export && |
| ofs->config.redirect_follow) { |
| pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); |
| ofs->config.nfs_export = false; |
| } |
| |
| err = -ENOMEM; |
| stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); |
| if (!stack) |
| goto out_err; |
| |
| err = -EINVAL; |
| lower = lowertmp; |
| for (numlower = 0; numlower < stacklen; numlower++) { |
| err = ovl_lower_dir(lower, &stack[numlower], ofs, |
| &sb->s_stack_depth, &remote); |
| if (err) |
| goto out_err; |
| |
| lower = strchr(lower, '\0') + 1; |
| } |
| |
| err = -EINVAL; |
| sb->s_stack_depth++; |
| if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
| pr_err("overlayfs: maximum fs stacking depth exceeded\n"); |
| goto out_err; |
| } |
| |
| err = ovl_get_lower_layers(sb, ofs, stack, numlower); |
| if (err) |
| goto out_err; |
| |
| err = -ENOMEM; |
| oe = ovl_alloc_entry(numlower); |
| if (!oe) |
| goto out_err; |
| |
| for (i = 0; i < numlower; i++) { |
| oe->lowerstack[i].dentry = dget(stack[i].dentry); |
| oe->lowerstack[i].layer = &ofs->lower_layers[i]; |
| } |
| |
| if (remote) |
| sb->s_d_op = &ovl_reval_dentry_operations; |
| else |
| sb->s_d_op = &ovl_dentry_operations; |
| |
| out: |
| for (i = 0; i < numlower; i++) |
| path_put(&stack[i]); |
| kfree(stack); |
| kfree(lowertmp); |
| |
| return oe; |
| |
| out_err: |
| oe = ERR_PTR(err); |
| goto out; |
| } |
| |
| /* |
| * 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("overlayfs: 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 (ofs->upper_mnt) { |
| err = ovl_check_layer(sb, ofs, ofs->upper_mnt->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 = 0; i < ofs->numlower; i++) { |
| err = ovl_check_layer(sb, ofs, |
| ofs->lower_layers[i].mnt->mnt_root, |
| "lowerdir", true); |
| if (err) |
| return err; |
| } |
| |
| return 0; |
| } |
| |
| static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
| { |
| struct path upperpath = { }; |
| struct dentry *root_dentry; |
| struct ovl_entry *oe; |
| struct ovl_fs *ofs; |
| struct cred *cred; |
| int err; |
| |
| err = -ENOMEM; |
| ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); |
| if (!ofs) |
| goto out; |
| |
| ofs->creator_cred = cred = prepare_creds(); |
| if (!cred) |
| goto out_err; |
| |
| ofs->config.index = ovl_index_def; |
| ofs->config.nfs_export = ovl_nfs_export_def; |
| ofs->config.xino = ovl_xino_def(); |
| ofs->config.metacopy = ovl_metacopy_def; |
| err = ovl_parse_opt((char *) data, &ofs->config); |
| if (err) |
| goto out_err; |
| |
| err = -EINVAL; |
| if (!ofs->config.lowerdir) { |
| if (!silent) |
| pr_err("overlayfs: missing 'lowerdir'\n"); |
| goto out_err; |
| } |
| |
| sb->s_stack_depth = 0; |
| sb->s_maxbytes = MAX_LFS_FILESIZE; |
| /* Assume underlaying fs uses 32bit inodes unless proven otherwise */ |
| if (ofs->config.xino != OVL_XINO_OFF) |
| ofs->xino_bits = BITS_PER_LONG - 32; |
| |
| /* alloc/destroy_inode needed for setting up traps in inode cache */ |
| sb->s_op = &ovl_super_operations; |
| |
| if (ofs->config.upperdir) { |
| if (!ofs->config.workdir) { |
| pr_err("overlayfs: missing 'workdir'\n"); |
| goto out_err; |
| } |
| |
| err = ovl_get_upper(sb, ofs, &upperpath); |
| if (err) |
| goto out_err; |
| |
| err = ovl_get_workdir(sb, ofs, &upperpath); |
| if (err) |
| goto out_err; |
| |
| if (!ofs->workdir) |
| sb->s_flags |= SB_RDONLY; |
| |
| sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth; |
| sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran; |
| |
| } |
| oe = ovl_get_lowerstack(sb, ofs); |
| err = PTR_ERR(oe); |
| if (IS_ERR(oe)) |
| goto out_err; |
| |
| /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
| if (!ofs->upper_mnt) |
| sb->s_flags |= SB_RDONLY; |
| |
| if (!(ovl_force_readonly(ofs)) && ofs->config.index) { |
| err = ovl_get_indexdir(sb, ofs, oe, &upperpath); |
| if (err) |
| goto out_free_oe; |
| |
| /* Force r/o mount with no index dir */ |
| if (!ofs->indexdir) { |
| dput(ofs->workdir); |
| ofs->workdir = NULL; |
| 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->indexdir) { |
| ofs->config.index = false; |
| if (ofs->upper_mnt && ofs->config.nfs_export) { |
| pr_warn("overlayfs: 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("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); |
| ofs->config.nfs_export = false; |
| } |
| |
| if (ofs->config.nfs_export) |
| sb->s_export_op = &ovl_export_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; |
| sb->s_fs_info = ofs; |
| sb->s_flags |= SB_POSIXACL; |
| |
| err = -ENOMEM; |
| root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); |
| if (!root_dentry) |
| goto out_free_oe; |
| |
| root_dentry->d_fsdata = oe; |
| |
| mntput(upperpath.mnt); |
| if (upperpath.dentry) { |
| ovl_dentry_set_upper_alias(root_dentry); |
| if (ovl_is_impuredir(upperpath.dentry)) |
| ovl_set_flag(OVL_IMPURE, d_inode(root_dentry)); |
| } |
| |
| /* Root is always merge -> can have whiteouts */ |
| ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry)); |
| ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry); |
| ovl_set_upperdata(d_inode(root_dentry)); |
| ovl_inode_init(d_inode(root_dentry), upperpath.dentry, |
| ovl_dentry_lower(root_dentry), NULL); |
| |
| sb->s_root = root_dentry; |
| |
| return 0; |
| |
| out_free_oe: |
| ovl_entry_stack_free(oe); |
| kfree(oe); |
| out_err: |
| path_put(&upperpath); |
| ovl_free_fs(ofs); |
| out: |
| return err; |
| } |
| |
| static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, |
| const char *dev_name, void *raw_data) |
| { |
| return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); |
| } |
| |
| static struct file_system_type ovl_fs_type = { |
| .owner = THIS_MODULE, |
| .name = "overlay", |
| .mount = ovl_mount, |
| .kill_sb = kill_anon_super, |
| }; |
| MODULE_ALIAS_FS("overlay"); |
| |
| static void ovl_inode_init_once(void *foo) |
| { |
| struct ovl_inode *oi = foo; |
| |
| inode_init_once(&oi->vfs_inode); |
| } |
| |
| static int __init ovl_init(void) |
| { |
| int err; |
| |
| ovl_inode_cachep = kmem_cache_create("ovl_inode", |
| sizeof(struct ovl_inode), 0, |
| (SLAB_RECLAIM_ACCOUNT| |
| SLAB_MEM_SPREAD|SLAB_ACCOUNT), |
| ovl_inode_init_once); |
| if (ovl_inode_cachep == NULL) |
| return -ENOMEM; |
| |
| err = register_filesystem(&ovl_fs_type); |
| if (err) |
| kmem_cache_destroy(ovl_inode_cachep); |
| |
| return err; |
| } |
| |
| static void __exit ovl_exit(void) |
| { |
| unregister_filesystem(&ovl_fs_type); |
| |
| /* |
| * Make sure all delayed rcu free inodes are flushed before we |
| * destroy cache. |
| */ |
| rcu_barrier(); |
| kmem_cache_destroy(ovl_inode_cachep); |
| |
| } |
| |
| module_init(ovl_init); |
| module_exit(ovl_exit); |