linux/kernel/audit_fsnotify.c
Amir Goldstein b9a1b97725 fsnotify: create method handle_inode_event() in fsnotify_operations
The method handle_event() grew a lot of complexity due to the design of
fanotify and merging of ignore masks.

Most backends do not care about this complex functionality, so we can hide
this complexity from them.

Introduce a method handle_inode_event() that serves those backends and
passes a single inode mark and less arguments.

This change converts all backends except fanotify and inotify to use the
simplified handle_inode_event() method.  In pricipal, inotify could have
also used the new method, but that would require passing more arguments
on the simple helper (data, data_type, cookie), so we leave it with the
handle_event() method.

Link: https://lore.kernel.org/r/20200722125849.17418-9-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2020-07-27 23:25:50 +02:00

193 lines
5.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* audit_fsnotify.c -- tracking inodes
*
* Copyright 2003-2009,2014-2015 Red Hat, Inc.
* Copyright 2005 Hewlett-Packard Development Company, L.P.
* Copyright 2005 IBM Corporation
*/
#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/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include "audit.h"
/*
* this mark lives on the parent directory of the inode in question.
* but dev, ino, and path are about the child
*/
struct audit_fsnotify_mark {
dev_t dev; /* associated superblock device */
unsigned long ino; /* associated inode number */
char *path; /* insertion path */
struct fsnotify_mark mark; /* fsnotify mark on the inode */
struct audit_krule *rule;
};
/* fsnotify handle. */
static struct fsnotify_group *audit_fsnotify_group;
/* fsnotify events we care about. */
#define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
FS_MOVE_SELF)
static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
{
kfree(audit_mark->path);
kfree(audit_mark);
}
static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
{
struct audit_fsnotify_mark *audit_mark;
audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
audit_fsnotify_mark_free(audit_mark);
}
char *audit_mark_path(struct audit_fsnotify_mark *mark)
{
return mark->path;
}
int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
{
if (mark->ino == AUDIT_INO_UNSET)
return 0;
return (mark->ino == ino) && (mark->dev == dev);
}
static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
const struct inode *inode)
{
audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
}
struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
{
struct audit_fsnotify_mark *audit_mark;
struct path path;
struct dentry *dentry;
struct inode *inode;
int ret;
if (pathname[0] != '/' || pathname[len-1] == '/')
return ERR_PTR(-EINVAL);
dentry = kern_path_locked(pathname, &path);
if (IS_ERR(dentry))
return (void *)dentry; /* returning an error */
inode = path.dentry->d_inode;
inode_unlock(inode);
audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
if (unlikely(!audit_mark)) {
audit_mark = ERR_PTR(-ENOMEM);
goto out;
}
fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
audit_mark->mark.mask = AUDIT_FS_EVENTS;
audit_mark->path = pathname;
audit_update_mark(audit_mark, dentry->d_inode);
audit_mark->rule = krule;
ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
if (ret < 0) {
fsnotify_put_mark(&audit_mark->mark);
audit_mark = ERR_PTR(ret);
}
out:
dput(dentry);
path_put(&path);
return audit_mark;
}
static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
{
struct audit_buffer *ab;
struct audit_krule *rule = audit_mark->rule;
if (!audit_enabled)
return;
ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
if (unlikely(!ab))
return;
audit_log_session_info(ab);
audit_log_format(ab, " op=%s path=", op);
audit_log_untrustedstring(ab, audit_mark->path);
audit_log_key(ab, rule->filterkey);
audit_log_format(ab, " list=%d res=1", rule->listnr);
audit_log_end(ab);
}
void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
{
fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
fsnotify_put_mark(&audit_mark->mark);
}
void audit_remove_mark_rule(struct audit_krule *krule)
{
struct audit_fsnotify_mark *mark = krule->exe;
audit_remove_mark(mark);
}
static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
{
struct audit_krule *rule = audit_mark->rule;
struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
audit_mark_log_rule_change(audit_mark, "autoremove_rule");
audit_del_rule(entry);
}
/* Update mark data in audit rules based on fsnotify events. */
static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
struct inode *inode, struct inode *dir,
const struct qstr *dname)
{
struct audit_fsnotify_mark *audit_mark;
audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group) ||
WARN_ON_ONCE(!inode))
return 0;
if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
return 0;
audit_update_mark(audit_mark, inode);
} else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) {
audit_autoremove_mark_rule(audit_mark);
}
return 0;
}
static const struct fsnotify_ops audit_mark_fsnotify_ops = {
.handle_inode_event = audit_mark_handle_event,
.free_mark = audit_fsnotify_free_mark,
};
static int __init audit_fsnotify_init(void)
{
audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
if (IS_ERR(audit_fsnotify_group)) {
audit_fsnotify_group = NULL;
audit_panic("cannot create audit fsnotify group");
}
return 0;
}
device_initcall(audit_fsnotify_init);