// SPDX-License-Identifier: GPL-2.0-or-later /* audit_watch.c -- watching inodes * * Copyright 2003-2009 Red Hat, Inc. * Copyright 2005 Hewlett-Packard Development Company, L.P. * Copyright 2005 IBM Corporation */ #include <linux/file.h> #include <linux/kernel.h> #include <linux/audit.h> #include <linux/kthread.h> #include <linux/mutex.h> #include <linux/fs.h> #include <linux/fsnotify_backend.h> #include <linux/namei.h> #include <linux/netlink.h> #include <linux/refcount.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/security.h> #include "audit.h" /* * Reference counting: * * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED * event. Each audit_watch holds a reference to its associated parent. * * audit_watch: if added to lists, lifetime is from audit_init_watch() to * audit_remove_watch(). Additionally, an audit_watch may exist * temporarily to assist in searching existing filter data. Each * audit_krule holds a reference to its associated watch. */ struct audit_watch { refcount_t count; /* reference count */ dev_t dev; /* associated superblock device */ char *path; /* insertion path */ unsigned long ino; /* associated inode number */ struct audit_parent *parent; /* associated parent */ struct list_head wlist; /* entry in parent->watches list */ struct list_head rules; /* anchor for krule->rlist */ }; struct audit_parent { struct list_head watches; /* anchor for audit_watch->wlist */ struct fsnotify_mark mark; /* fsnotify mark on the inode */ }; /* fsnotify handle. */ static struct fsnotify_group *audit_watch_group; /* fsnotify events we care about. */ #define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\ FS_MOVE_SELF | FS_UNMOUNT) static void audit_free_parent(struct audit_parent *parent) { WARN_ON(!list_empty(&parent->watches)); kfree(parent); } static void audit_watch_free_mark(struct fsnotify_mark *entry) { struct audit_parent *parent; parent = container_of(entry, struct audit_parent, mark); audit_free_parent(parent); } static void audit_get_parent(struct audit_parent *parent) { if (likely(parent)) fsnotify_get_mark(&parent->mark); } static void audit_put_parent(struct audit_parent *parent) { if (likely(parent)) fsnotify_put_mark(&parent->mark); } /* * Find and return the audit_parent on the given inode. If found a reference * is taken on this parent. */ static inline struct audit_parent *audit_find_parent(struct inode *inode) { struct audit_parent *parent = NULL; struct fsnotify_mark *entry; entry = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_watch_group); if (entry) parent = container_of(entry, struct audit_parent, mark); return parent; } void audit_get_watch(struct audit_watch *watch) { refcount_inc(&watch->count); } void audit_put_watch(struct audit_watch *watch) { if (refcount_dec_and_test(&watch->count)) { WARN_ON(watch->parent); WARN_ON(!list_empty(&watch->rules)); kfree(watch->path); kfree(watch); } } static void audit_remove_watch(struct audit_watch *watch) { list_del(&watch->wlist); audit_put_parent(watch->parent); watch->parent = NULL; audit_put_watch(watch); /* match initial get */ } char *audit_watch_path(struct audit_watch *watch) { return watch->path; } int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev) { return (watch->ino != AUDIT_INO_UNSET) && (watch->ino == ino) && (watch->dev == dev); } /* Initialize a parent watch entry. */ static struct audit_parent *audit_init_parent(struct path *path) { struct inode *inode = d_backing_inode(path->dentry); struct audit_parent *parent; int ret; parent = kzalloc(sizeof(*parent), GFP_KERNEL); if (unlikely(!parent)) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&parent->watches); fsnotify_init_mark(&parent->mark, audit_watch_group); parent->mark.mask = AUDIT_FS_WATCH; ret = fsnotify_add_inode_mark(&parent->mark, inode, 0); if (ret < 0) { audit_free_parent(parent); return ERR_PTR(ret); } return parent; } /* Initialize a watch entry. */ static struct audit_watch *audit_init_watch(char *path) { struct audit_watch *watch; watch = kzalloc(sizeof(*watch), GFP_KERNEL); if (unlikely(!watch)) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&watch->rules); refcount_set(&watch->count, 1); watch->path = path; watch->dev = AUDIT_DEV_UNSET; watch->ino = AUDIT_INO_UNSET; return watch; } /* Translate a watch string to kernel representation. */ int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op) { struct audit_watch *watch; if (!audit_watch_group) return -EOPNOTSUPP; if (path[0] != '/' || path[len-1] == '/' || krule->listnr != AUDIT_FILTER_EXIT || op != Audit_equal || krule->inode_f || krule->watch || krule->tree) return -EINVAL; watch = audit_init_watch(path); if (IS_ERR(watch)) return PTR_ERR(watch); krule->watch = watch; return 0; } /* Duplicate the given audit watch. The new watch's rules list is initialized * to an empty list and wlist is undefined. */ static struct audit_watch *audit_dupe_watch(struct audit_watch *old) { char *path; struct audit_watch *new; path = kstrdup(old->path, GFP_KERNEL); if (unlikely(!path)) return ERR_PTR(-ENOMEM); new = audit_init_watch(path); if (IS_ERR(new)) { kfree(path); goto out; } new->dev = old->dev; new->ino = old->ino; audit_get_parent(old->parent); new->parent = old->parent; out: return new; } static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op) { struct audit_buffer *ab; if (!audit_enabled) return; ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE); if (!ab) return; audit_log_session_info(ab); audit_log_format(ab, "op=%s path=", op); audit_log_untrustedstring(ab, w->path); audit_log_key(ab, r->filterkey); audit_log_format(ab, " list=%d res=1", r->listnr); audit_log_end(ab); } /* Update inode info in audit rules based on filesystem event. */ static void audit_update_watch(struct audit_parent *parent, const struct qstr *dname, dev_t dev, unsigned long ino, unsigned invalidating) { struct audit_watch *owatch, *nwatch, *nextw; struct audit_krule *r, *nextr; struct audit_entry *oentry, *nentry; mutex_lock(&audit_filter_mutex); /* Run all of the watches on this parent looking for the one that * matches the given dname */ list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) { if (audit_compare_dname_path(dname, owatch->path, AUDIT_NAME_FULL)) continue; /* If the update involves invalidating rules, do the inode-based * filtering now, so we don't omit records. */ if (invalidating && !audit_dummy_context()) audit_filter_inodes(current, audit_context()); /* updating ino will likely change which audit_hash_list we * are on so we need a new watch for the new list */ nwatch = audit_dupe_watch(owatch); if (IS_ERR(nwatch)) { mutex_unlock(&audit_filter_mutex); audit_panic("error updating watch, skipping"); return; } nwatch->dev = dev; nwatch->ino = ino; list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) { oentry = container_of(r, struct audit_entry, rule); list_del(&oentry->rule.rlist); list_del_rcu(&oentry->list); nentry = audit_dupe_rule(&oentry->rule); if (IS_ERR(nentry)) { list_del(&oentry->rule.list); audit_panic("error updating watch, removing"); } else { int h = audit_hash_ino((u32)ino); /* * nentry->rule.watch == oentry->rule.watch so * we must drop that reference and set it to our * new watch. */ audit_put_watch(nentry->rule.watch); audit_get_watch(nwatch); nentry->rule.watch = nwatch; list_add(&nentry->rule.rlist, &nwatch->rules); list_add_rcu(&nentry->list, &audit_inode_hash[h]); list_replace(&oentry->rule.list, &nentry->rule.list); } if (oentry->rule.exe) audit_remove_mark(oentry->rule.exe); call_rcu(&oentry->rcu, audit_free_rule_rcu); } audit_remove_watch(owatch); goto add_watch_to_parent; /* event applies to a single watch */ } mutex_unlock(&audit_filter_mutex); return; add_watch_to_parent: list_add(&nwatch->wlist, &parent->watches); mutex_unlock(&audit_filter_mutex); return; } /* Remove all watches & rules associated with a parent that is going away. */ static void audit_remove_parent_watches(struct audit_parent *parent) { struct audit_watch *w, *nextw; struct audit_krule *r, *nextr; struct audit_entry *e; mutex_lock(&audit_filter_mutex); list_for_each_entry_safe(w, nextw, &parent->watches, wlist) { list_for_each_entry_safe(r, nextr, &w->rules, rlist) { e = container_of(r, struct audit_entry, rule); audit_watch_log_rule_change(r, w, "remove_rule"); if (e->rule.exe) audit_remove_mark(e->rule.exe); list_del(&r->rlist); list_del(&r->list); list_del_rcu(&e->list); call_rcu(&e->rcu, audit_free_rule_rcu); } audit_remove_watch(w); } mutex_unlock(&audit_filter_mutex); fsnotify_destroy_mark(&parent->mark, audit_watch_group); } /* Get path information necessary for adding watches. */ static int audit_get_nd(struct audit_watch *watch, struct path *parent) { struct dentry *d = kern_path_locked(watch->path, parent); if (IS_ERR(d)) return PTR_ERR(d); if (d_is_positive(d)) { /* update watch filter fields */ watch->dev = d->d_sb->s_dev; watch->ino = d_backing_inode(d)->i_ino; } inode_unlock(d_backing_inode(parent->dentry)); dput(d); return 0; } /* Associate the given rule with an existing parent. * Caller must hold audit_filter_mutex. */ static void audit_add_to_parent(struct audit_krule *krule, struct audit_parent *parent) { struct audit_watch *w, *watch = krule->watch; int watch_found = 0; BUG_ON(!mutex_is_locked(&audit_filter_mutex)); list_for_each_entry(w, &parent->watches, wlist) { if (strcmp(watch->path, w->path)) continue; watch_found = 1; /* put krule's ref to temporary watch */ audit_put_watch(watch); audit_get_watch(w); krule->watch = watch = w; audit_put_parent(parent); break; } if (!watch_found) { watch->parent = parent; audit_get_watch(watch); list_add(&watch->wlist, &parent->watches); } list_add(&krule->rlist, &watch->rules); } /* Find a matching watch entry, or add this one. * Caller must hold audit_filter_mutex. */ int audit_add_watch(struct audit_krule *krule, struct list_head **list) { struct audit_watch *watch = krule->watch; struct audit_parent *parent; struct path parent_path; int h, ret = 0; /* * When we will be calling audit_add_to_parent, krule->watch might have * been updated and watch might have been freed. * So we need to keep a reference of watch. */ audit_get_watch(watch); mutex_unlock(&audit_filter_mutex); /* Avoid calling path_lookup under audit_filter_mutex. */ ret = audit_get_nd(watch, &parent_path); /* caller expects mutex locked */ mutex_lock(&audit_filter_mutex); if (ret) { audit_put_watch(watch); return ret; } /* either find an old parent or attach a new one */ parent = audit_find_parent(d_backing_inode(parent_path.dentry)); if (!parent) { parent = audit_init_parent(&parent_path); if (IS_ERR(parent)) { ret = PTR_ERR(parent); goto error; } } audit_add_to_parent(krule, parent); h = audit_hash_ino((u32)watch->ino); *list = &audit_inode_hash[h]; error: path_put(&parent_path); audit_put_watch(watch); return ret; } void audit_remove_watch_rule(struct audit_krule *krule) { struct audit_watch *watch = krule->watch; struct audit_parent *parent = watch->parent; list_del(&krule->rlist); if (list_empty(&watch->rules)) { /* * audit_remove_watch() drops our reference to 'parent' which * can get freed. Grab our own reference to be safe. */ audit_get_parent(parent); audit_remove_watch(watch); if (list_empty(&parent->watches)) fsnotify_destroy_mark(&parent->mark, audit_watch_group); audit_put_parent(parent); } } /* Update watch data in audit rules based on fsnotify events. */ static int audit_watch_handle_event(struct fsnotify_mark *inode_mark, u32 mask, struct inode *inode, struct inode *dir, const struct qstr *dname, u32 cookie) { struct audit_parent *parent; parent = container_of(inode_mark, struct audit_parent, mark); if (WARN_ON_ONCE(inode_mark->group != audit_watch_group) || WARN_ON_ONCE(!inode)) return 0; if (mask & (FS_CREATE|FS_MOVED_TO) && inode) audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0); else if (mask & (FS_DELETE|FS_MOVED_FROM)) audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1); else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) audit_remove_parent_watches(parent); return 0; } static const struct fsnotify_ops audit_watch_fsnotify_ops = { .handle_inode_event = audit_watch_handle_event, .free_mark = audit_watch_free_mark, }; static int __init audit_watch_init(void) { audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops); if (IS_ERR(audit_watch_group)) { audit_watch_group = NULL; audit_panic("cannot create audit fsnotify group"); } return 0; } device_initcall(audit_watch_init); int audit_dupe_exe(struct audit_krule *new, struct audit_krule *old) { struct audit_fsnotify_mark *audit_mark; char *pathname; pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL); if (!pathname) return -ENOMEM; audit_mark = audit_alloc_mark(new, pathname, strlen(pathname)); if (IS_ERR(audit_mark)) { kfree(pathname); return PTR_ERR(audit_mark); } new->exe = audit_mark; return 0; } int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark) { struct file *exe_file; unsigned long ino; dev_t dev; exe_file = get_task_exe_file(tsk); if (!exe_file) return 0; ino = file_inode(exe_file)->i_ino; dev = file_inode(exe_file)->i_sb->s_dev; fput(exe_file); return audit_mark_compare(mark, ino, dev); }