audit_fsnotify.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* audit_fsnotify.c -- tracking inodes
  3 *
  4 * Copyright 2003-2009,2014-2015 Red Hat, Inc.
  5 * Copyright 2005 Hewlett-Packard Development Company, L.P.
  6 * Copyright 2005 IBM Corporation
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/audit.h>
 11#include <linux/kthread.h>
 12#include <linux/mutex.h>
 13#include <linux/fs.h>
 14#include <linux/fsnotify_backend.h>
 15#include <linux/namei.h>
 16#include <linux/netlink.h>
 17#include <linux/sched.h>
 18#include <linux/slab.h>
 19#include <linux/security.h>
 20#include "audit.h"
 21
 22/*
 23 * this mark lives on the parent directory of the inode in question.
 24 * but dev, ino, and path are about the child
 25 */
 26struct audit_fsnotify_mark {
 27	dev_t dev;		/* associated superblock device */
 28	unsigned long ino;	/* associated inode number */
 29	char *path;		/* insertion path */
 30	struct fsnotify_mark mark; /* fsnotify mark on the inode */
 31	struct audit_krule *rule;
 32};
 33
 34/* fsnotify handle. */
 35static struct fsnotify_group *audit_fsnotify_group;
 36
 37/* fsnotify events we care about. */
 38#define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
 39			 FS_MOVE_SELF)
 40
 41static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
 42{
 43	kfree(audit_mark->path);
 44	kfree(audit_mark);
 45}
 46
 47static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
 48{
 49	struct audit_fsnotify_mark *audit_mark;
 50
 51	audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
 52	audit_fsnotify_mark_free(audit_mark);
 53}
 54
 55char *audit_mark_path(struct audit_fsnotify_mark *mark)
 56{
 57	return mark->path;
 58}
 59
 60int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
 61{
 62	if (mark->ino == AUDIT_INO_UNSET)
 63		return 0;
 64	return (mark->ino == ino) && (mark->dev == dev);
 65}
 66
 67static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
 68			     const struct inode *inode)
 69{
 70	audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
 71	audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
 72}
 73
 74struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
 75{
 76	struct audit_fsnotify_mark *audit_mark;
 77	struct path path;
 78	struct dentry *dentry;
 79	int ret;
 80
 81	if (pathname[0] != '/' || pathname[len-1] == '/')
 82		return ERR_PTR(-EINVAL);
 83
 84	dentry = kern_path_parent(pathname, &path);
 85	if (IS_ERR(dentry))
 86		return ERR_CAST(dentry); /* returning an error */
 87	if (d_really_is_negative(dentry)) {
 88		audit_mark = ERR_PTR(-ENOENT);
 89		goto out;
 90	}
 91
 92	audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
 93	if (unlikely(!audit_mark)) {
 94		audit_mark = ERR_PTR(-ENOMEM);
 95		goto out;
 96	}
 97
 98	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
 99	audit_mark->mark.mask = AUDIT_FS_EVENTS;
100	audit_mark->path = pathname;
101	audit_update_mark(audit_mark, dentry->d_inode);
102	audit_mark->rule = krule;
103
104	ret = fsnotify_add_inode_mark(&audit_mark->mark, path.dentry->d_inode, 0);
105	if (ret < 0) {
106		audit_mark->path = NULL;
107		fsnotify_put_mark(&audit_mark->mark);
108		audit_mark = ERR_PTR(ret);
109	}
110out:
111	dput(dentry);
112	path_put(&path);
113	return audit_mark;
114}
115
116static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
117{
118	struct audit_buffer *ab;
119	struct audit_krule *rule = audit_mark->rule;
120
121	if (!audit_enabled)
122		return;
123	ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
124	if (unlikely(!ab))
125		return;
126	audit_log_session_info(ab);
127	audit_log_format(ab, " op=%s path=", op);
128	audit_log_untrustedstring(ab, audit_mark->path);
129	audit_log_key(ab, rule->filterkey);
130	audit_log_format(ab, " list=%d res=1", rule->listnr);
131	audit_log_end(ab);
132}
133
134void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
135{
136	fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
137	fsnotify_put_mark(&audit_mark->mark);
138}
139
140void audit_remove_mark_rule(struct audit_krule *krule)
141{
142	struct audit_fsnotify_mark *mark = krule->exe;
143
144	audit_remove_mark(mark);
145}
146
147static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
148{
149	struct audit_krule *rule = audit_mark->rule;
150	struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
151
152	audit_mark_log_rule_change(audit_mark, "autoremove_rule");
153	audit_del_rule(entry);
154}
155
156/* Update mark data in audit rules based on fsnotify events. */
157static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
158				   struct inode *inode, struct inode *dir,
159				   const struct qstr *dname, u32 cookie)
160{
161	struct audit_fsnotify_mark *audit_mark;
162
163	audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
164
165	if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group))
166		return 0;
167
168	if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
169		if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
170			return 0;
171		audit_update_mark(audit_mark, inode);
172	} else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) {
173		audit_autoremove_mark_rule(audit_mark);
174	}
175
176	return 0;
177}
178
179static const struct fsnotify_ops audit_mark_fsnotify_ops = {
180	.handle_inode_event = audit_mark_handle_event,
181	.free_mark = audit_fsnotify_free_mark,
182};
183
184static int __init audit_fsnotify_init(void)
185{
186	audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops,
187						    FSNOTIFY_GROUP_DUPS);
188	if (IS_ERR(audit_fsnotify_group)) {
189		audit_fsnotify_group = NULL;
190		audit_panic("cannot create audit fsnotify group");
191	}
192	return 0;
193}
194device_initcall(audit_fsnotify_init);