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synced 2024-08-27 11:19:37 +00:00
![Amir Goldstein](/assets/img/avatar_default.png)
The handle_inode_event() interface was added as (quoting comment):
"a simple variant of handle_event() for groups that only have inode
marks and don't have ignore mask".
In other words, all backends except fanotify. The inotify backend
also falls under this category, but because it required extra arguments
it was left out of the initial pass of backends conversion to the
simple interface.
This results in code duplication between the generic helper
fsnotify_handle_event() and the inotify_handle_event() callback
which also happen to be buggy code.
Generalize the handle_inode_event() arguments and add the check for
FS_EXCL_UNLINK flag to the generic helper, so inotify backend could
be converted to use the simple interface.
Link: https://lore.kernel.org/r/20201202120713.702387-2-amir73il@gmail.com
CC: stable@vger.kernel.org
Fixes: b9a1b97725
("fsnotify: create method handle_inode_event() in fsnotify_operations")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
537 lines
14 KiB
C
537 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* 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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#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/refcount.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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refcount_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_UNMOUNT)
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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_mark(&inode->i_fsnotify_marks, audit_watch_group);
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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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refcount_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 (refcount_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_group);
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parent->mark.mask = AUDIT_FS_WATCH;
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ret = fsnotify_add_inode_mark(&parent->mark, inode, 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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refcount_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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struct audit_buffer *ab;
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if (!audit_enabled)
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return;
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ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
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if (!ab)
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return;
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audit_log_session_info(ab);
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audit_log_format(ab, "op=%s path=", op);
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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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/* 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 struct qstr *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, 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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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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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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inode_unlock(d_backing_inode(parent->dentry));
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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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/*
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* When we will be calling audit_add_to_parent, krule->watch might have
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* been updated and watch might have been freed.
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* So we need to keep a reference of watch.
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*/
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audit_get_watch(watch);
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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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audit_put_watch(watch);
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return ret;
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}
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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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audit_put_watch(watch);
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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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/*
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* audit_remove_watch() drops our reference to 'parent' which
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* can get freed. Grab our own reference to be safe.
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*/
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audit_get_parent(parent);
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audit_remove_watch(watch);
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if (list_empty(&parent->watches))
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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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/* Update watch data in audit rules based on fsnotify events. */
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static int audit_watch_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
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struct inode *inode, struct inode *dir,
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const struct qstr *dname, u32 cookie)
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{
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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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if (WARN_ON_ONCE(inode_mark->group != audit_watch_group) ||
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WARN_ON_ONCE(!inode))
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return 0;
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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_inode_event = audit_watch_handle_event,
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.free_mark = audit_watch_free_mark,
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};
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static int __init audit_watch_init(void)
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{
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audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops);
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if (IS_ERR(audit_watch_group)) {
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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);
|
|
}
|