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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Linus Torvalds](/assets/img/avatar_default.png)
Pull audit fixes from Paul Moore: "Two small patches to fix some bugs with the audit-by-executable functionality we introduced back in v4.3 (both patches are marked for the stable folks)" * 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit: audit: fix exe_file access in audit_exe_compare mm: introduce get_task_exe_file
555 lines
14 KiB
C
555 lines
14 KiB
C
/* audit_watch.c -- watching inodes
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*
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* Copyright 2003-2009 Red Hat, Inc.
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* Copyright 2005 Hewlett-Packard Development Company, L.P.
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* Copyright 2005 IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/file.h>
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#include <linux/kernel.h>
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#include <linux/audit.h>
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#include <linux/kthread.h>
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#include <linux/mutex.h>
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#include <linux/fs.h>
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#include <linux/fsnotify_backend.h>
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#include <linux/namei.h>
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#include <linux/netlink.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include "audit.h"
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/*
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* Reference counting:
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*
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* audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED
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* event. Each audit_watch holds a reference to its associated parent.
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*
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* audit_watch: if added to lists, lifetime is from audit_init_watch() to
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* audit_remove_watch(). Additionally, an audit_watch may exist
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* temporarily to assist in searching existing filter data. Each
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* audit_krule holds a reference to its associated watch.
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*/
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struct audit_watch {
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atomic_t count; /* reference count */
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dev_t dev; /* associated superblock device */
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char *path; /* insertion path */
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unsigned long ino; /* associated inode number */
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struct audit_parent *parent; /* associated parent */
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struct list_head wlist; /* entry in parent->watches list */
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struct list_head rules; /* anchor for krule->rlist */
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};
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struct audit_parent {
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struct list_head watches; /* anchor for audit_watch->wlist */
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struct fsnotify_mark mark; /* fsnotify mark on the inode */
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};
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/* fsnotify handle. */
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static struct fsnotify_group *audit_watch_group;
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/* fsnotify events we care about. */
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#define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
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FS_MOVE_SELF | FS_EVENT_ON_CHILD)
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static void audit_free_parent(struct audit_parent *parent)
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{
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WARN_ON(!list_empty(&parent->watches));
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kfree(parent);
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}
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static void audit_watch_free_mark(struct fsnotify_mark *entry)
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{
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struct audit_parent *parent;
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parent = container_of(entry, struct audit_parent, mark);
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audit_free_parent(parent);
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}
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static void audit_get_parent(struct audit_parent *parent)
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{
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if (likely(parent))
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fsnotify_get_mark(&parent->mark);
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}
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static void audit_put_parent(struct audit_parent *parent)
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{
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if (likely(parent))
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fsnotify_put_mark(&parent->mark);
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}
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/*
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* Find and return the audit_parent on the given inode. If found a reference
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* is taken on this parent.
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*/
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static inline struct audit_parent *audit_find_parent(struct inode *inode)
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{
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struct audit_parent *parent = NULL;
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struct fsnotify_mark *entry;
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entry = fsnotify_find_inode_mark(audit_watch_group, inode);
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if (entry)
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parent = container_of(entry, struct audit_parent, mark);
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return parent;
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}
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void audit_get_watch(struct audit_watch *watch)
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{
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atomic_inc(&watch->count);
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}
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void audit_put_watch(struct audit_watch *watch)
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{
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if (atomic_dec_and_test(&watch->count)) {
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WARN_ON(watch->parent);
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WARN_ON(!list_empty(&watch->rules));
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kfree(watch->path);
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kfree(watch);
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}
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}
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static void audit_remove_watch(struct audit_watch *watch)
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{
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list_del(&watch->wlist);
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audit_put_parent(watch->parent);
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watch->parent = NULL;
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audit_put_watch(watch); /* match initial get */
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}
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char *audit_watch_path(struct audit_watch *watch)
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{
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return watch->path;
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}
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int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
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{
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return (watch->ino != AUDIT_INO_UNSET) &&
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(watch->ino == ino) &&
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(watch->dev == dev);
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}
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/* Initialize a parent watch entry. */
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static struct audit_parent *audit_init_parent(struct path *path)
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{
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struct inode *inode = d_backing_inode(path->dentry);
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struct audit_parent *parent;
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int ret;
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parent = kzalloc(sizeof(*parent), GFP_KERNEL);
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if (unlikely(!parent))
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&parent->watches);
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fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
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parent->mark.mask = AUDIT_FS_WATCH;
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ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0);
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if (ret < 0) {
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audit_free_parent(parent);
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return ERR_PTR(ret);
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}
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return parent;
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}
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/* Initialize a watch entry. */
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static struct audit_watch *audit_init_watch(char *path)
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{
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struct audit_watch *watch;
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watch = kzalloc(sizeof(*watch), GFP_KERNEL);
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if (unlikely(!watch))
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&watch->rules);
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atomic_set(&watch->count, 1);
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watch->path = path;
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watch->dev = AUDIT_DEV_UNSET;
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watch->ino = AUDIT_INO_UNSET;
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return watch;
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}
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/* Translate a watch string to kernel representation. */
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int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
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{
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struct audit_watch *watch;
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if (!audit_watch_group)
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return -EOPNOTSUPP;
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if (path[0] != '/' || path[len-1] == '/' ||
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krule->listnr != AUDIT_FILTER_EXIT ||
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op != Audit_equal ||
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krule->inode_f || krule->watch || krule->tree)
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return -EINVAL;
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watch = audit_init_watch(path);
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if (IS_ERR(watch))
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return PTR_ERR(watch);
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krule->watch = watch;
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return 0;
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}
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/* Duplicate the given audit watch. The new watch's rules list is initialized
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* to an empty list and wlist is undefined. */
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static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
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{
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char *path;
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struct audit_watch *new;
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path = kstrdup(old->path, GFP_KERNEL);
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if (unlikely(!path))
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return ERR_PTR(-ENOMEM);
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new = audit_init_watch(path);
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if (IS_ERR(new)) {
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kfree(path);
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goto out;
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}
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new->dev = old->dev;
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new->ino = old->ino;
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audit_get_parent(old->parent);
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new->parent = old->parent;
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out:
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return new;
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}
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static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
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{
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if (audit_enabled) {
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struct audit_buffer *ab;
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ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
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if (unlikely(!ab))
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return;
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audit_log_format(ab, "auid=%u ses=%u op=",
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from_kuid(&init_user_ns, audit_get_loginuid(current)),
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audit_get_sessionid(current));
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audit_log_string(ab, op);
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audit_log_format(ab, " path=");
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audit_log_untrustedstring(ab, w->path);
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audit_log_key(ab, r->filterkey);
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audit_log_format(ab, " list=%d res=1", r->listnr);
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audit_log_end(ab);
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}
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}
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/* Update inode info in audit rules based on filesystem event. */
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static void audit_update_watch(struct audit_parent *parent,
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const char *dname, dev_t dev,
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unsigned long ino, unsigned invalidating)
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{
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struct audit_watch *owatch, *nwatch, *nextw;
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struct audit_krule *r, *nextr;
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struct audit_entry *oentry, *nentry;
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mutex_lock(&audit_filter_mutex);
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/* Run all of the watches on this parent looking for the one that
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* matches the given dname */
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list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
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if (audit_compare_dname_path(dname, owatch->path,
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AUDIT_NAME_FULL))
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continue;
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/* If the update involves invalidating rules, do the inode-based
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* filtering now, so we don't omit records. */
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if (invalidating && !audit_dummy_context())
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audit_filter_inodes(current, current->audit_context);
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/* updating ino will likely change which audit_hash_list we
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* are on so we need a new watch for the new list */
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nwatch = audit_dupe_watch(owatch);
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if (IS_ERR(nwatch)) {
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mutex_unlock(&audit_filter_mutex);
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audit_panic("error updating watch, skipping");
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return;
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}
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nwatch->dev = dev;
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nwatch->ino = ino;
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list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
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oentry = container_of(r, struct audit_entry, rule);
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list_del(&oentry->rule.rlist);
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list_del_rcu(&oentry->list);
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nentry = audit_dupe_rule(&oentry->rule);
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if (IS_ERR(nentry)) {
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list_del(&oentry->rule.list);
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audit_panic("error updating watch, removing");
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} else {
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int h = audit_hash_ino((u32)ino);
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/*
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* nentry->rule.watch == oentry->rule.watch so
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* we must drop that reference and set it to our
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* new watch.
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*/
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audit_put_watch(nentry->rule.watch);
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audit_get_watch(nwatch);
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nentry->rule.watch = nwatch;
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list_add(&nentry->rule.rlist, &nwatch->rules);
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list_add_rcu(&nentry->list, &audit_inode_hash[h]);
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list_replace(&oentry->rule.list,
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&nentry->rule.list);
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}
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if (oentry->rule.exe)
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audit_remove_mark(oentry->rule.exe);
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audit_watch_log_rule_change(r, owatch, "updated_rules");
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call_rcu(&oentry->rcu, audit_free_rule_rcu);
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}
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audit_remove_watch(owatch);
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goto add_watch_to_parent; /* event applies to a single watch */
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}
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mutex_unlock(&audit_filter_mutex);
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return;
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add_watch_to_parent:
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list_add(&nwatch->wlist, &parent->watches);
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mutex_unlock(&audit_filter_mutex);
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return;
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}
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/* Remove all watches & rules associated with a parent that is going away. */
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static void audit_remove_parent_watches(struct audit_parent *parent)
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{
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struct audit_watch *w, *nextw;
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struct audit_krule *r, *nextr;
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struct audit_entry *e;
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mutex_lock(&audit_filter_mutex);
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list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
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list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
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e = container_of(r, struct audit_entry, rule);
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audit_watch_log_rule_change(r, w, "remove_rule");
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if (e->rule.exe)
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audit_remove_mark(e->rule.exe);
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list_del(&r->rlist);
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list_del(&r->list);
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list_del_rcu(&e->list);
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call_rcu(&e->rcu, audit_free_rule_rcu);
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}
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audit_remove_watch(w);
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}
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mutex_unlock(&audit_filter_mutex);
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fsnotify_destroy_mark(&parent->mark, audit_watch_group);
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}
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/* Get path information necessary for adding watches. */
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static int audit_get_nd(struct audit_watch *watch, struct path *parent)
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{
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struct dentry *d = kern_path_locked(watch->path, parent);
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if (IS_ERR(d))
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return PTR_ERR(d);
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inode_unlock(d_backing_inode(parent->dentry));
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if (d_is_positive(d)) {
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/* update watch filter fields */
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watch->dev = d->d_sb->s_dev;
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watch->ino = d_backing_inode(d)->i_ino;
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}
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dput(d);
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return 0;
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}
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/* Associate the given rule with an existing parent.
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* Caller must hold audit_filter_mutex. */
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static void audit_add_to_parent(struct audit_krule *krule,
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struct audit_parent *parent)
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{
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struct audit_watch *w, *watch = krule->watch;
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int watch_found = 0;
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BUG_ON(!mutex_is_locked(&audit_filter_mutex));
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list_for_each_entry(w, &parent->watches, wlist) {
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if (strcmp(watch->path, w->path))
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continue;
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watch_found = 1;
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/* put krule's ref to temporary watch */
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audit_put_watch(watch);
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audit_get_watch(w);
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krule->watch = watch = w;
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audit_put_parent(parent);
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break;
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}
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if (!watch_found) {
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watch->parent = parent;
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audit_get_watch(watch);
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list_add(&watch->wlist, &parent->watches);
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}
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list_add(&krule->rlist, &watch->rules);
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}
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/* Find a matching watch entry, or add this one.
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* Caller must hold audit_filter_mutex. */
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int audit_add_watch(struct audit_krule *krule, struct list_head **list)
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{
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struct audit_watch *watch = krule->watch;
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struct audit_parent *parent;
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struct path parent_path;
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int h, ret = 0;
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mutex_unlock(&audit_filter_mutex);
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/* Avoid calling path_lookup under audit_filter_mutex. */
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ret = audit_get_nd(watch, &parent_path);
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/* caller expects mutex locked */
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mutex_lock(&audit_filter_mutex);
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if (ret)
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return ret;
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/* either find an old parent or attach a new one */
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parent = audit_find_parent(d_backing_inode(parent_path.dentry));
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if (!parent) {
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parent = audit_init_parent(&parent_path);
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if (IS_ERR(parent)) {
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ret = PTR_ERR(parent);
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goto error;
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}
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}
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audit_add_to_parent(krule, parent);
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h = audit_hash_ino((u32)watch->ino);
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*list = &audit_inode_hash[h];
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error:
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path_put(&parent_path);
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return ret;
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}
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void audit_remove_watch_rule(struct audit_krule *krule)
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{
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struct audit_watch *watch = krule->watch;
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struct audit_parent *parent = watch->parent;
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list_del(&krule->rlist);
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if (list_empty(&watch->rules)) {
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audit_remove_watch(watch);
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if (list_empty(&parent->watches)) {
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audit_get_parent(parent);
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fsnotify_destroy_mark(&parent->mark, audit_watch_group);
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audit_put_parent(parent);
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}
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}
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}
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/* Update watch data in audit rules based on fsnotify events. */
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static int audit_watch_handle_event(struct fsnotify_group *group,
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struct inode *to_tell,
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struct fsnotify_mark *inode_mark,
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struct fsnotify_mark *vfsmount_mark,
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u32 mask, void *data, int data_type,
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const unsigned char *dname, u32 cookie)
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{
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struct inode *inode;
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struct audit_parent *parent;
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parent = container_of(inode_mark, struct audit_parent, mark);
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BUG_ON(group != audit_watch_group);
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switch (data_type) {
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case (FSNOTIFY_EVENT_PATH):
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inode = d_backing_inode(((struct path *)data)->dentry);
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break;
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case (FSNOTIFY_EVENT_INODE):
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inode = (struct inode *)data;
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break;
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default:
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BUG();
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inode = NULL;
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break;
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};
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if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
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audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
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else if (mask & (FS_DELETE|FS_MOVED_FROM))
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audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1);
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else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
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audit_remove_parent_watches(parent);
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return 0;
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}
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static const struct fsnotify_ops audit_watch_fsnotify_ops = {
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.handle_event = audit_watch_handle_event,
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};
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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 = exe_file->f_inode->i_ino;
|
|
dev = exe_file->f_inode->i_sb->s_dev;
|
|
fput(exe_file);
|
|
return audit_mark_compare(mark, ino, dev);
|
|
}
|