LXR linux/kernel/audit

   1/* audit_fsnotify.c -- tracking inodes
   2 *
   3 * Copyright 2003-2009,2014-2015 Red Hat, Inc.
   4 * Copyright 2005 Hewlett-Packard Development Company, L.P.
   5 * Copyright 2005 IBM Corporation
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 */
  17
  18#include <linux/kernel.h>
  19#include <linux/audit.h>
  20#include <linux/kthread.h>
  21#include <linux/mutex.h>
  22#include <linux/fs.h>
  23#include <linux/fsnotify_backend.h>
  24#include <linux/namei.h>
  25#include <linux/netlink.h>
  26#include <linux/sched.h>
  27#include <linux/slab.h>
  28#include <linux/security.h>
  29#include "audit.h"
  30
  31/*
  32 * this mark lives on the parent directory of the inode in question.
  33 * but dev, ino, and path are about the child
  34 */
  35struct audit_fsnotify_mark {
  36        dev_t dev;              /* associated superblock device */
  37        unsigned long ino;      /* associated inode number */
  38        char *path;             /* insertion path */
  39        struct fsnotify_mark mark; /* fsnotify mark on the inode */
  40        struct audit_krule *rule;
  41};
  42
  43/* fsnotify handle. */
  44static struct fsnotify_group *audit_fsnotify_group;
  45
  46/* fsnotify events we care about. */
  47#define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
  48                         FS_MOVE_SELF | FS_EVENT_ON_CHILD)
  49
  50static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
  51{
  52        kfree(audit_mark->path);
  53        kfree(audit_mark);
  54}
  55
  56static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
  57{
  58        struct audit_fsnotify_mark *audit_mark;
  59
  60        audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
  61        audit_fsnotify_mark_free(audit_mark);
  62}
  63
  64char *audit_mark_path(struct audit_fsnotify_mark *mark)
  65{
  66        return mark->path;
  67}
  68
  69int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
  70{
  71        if (mark->ino == AUDIT_INO_UNSET)
  72                return 0;
  73        return (mark->ino == ino) && (mark->dev == dev);
  74}
  75
  76static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
  77                             const struct inode *inode)
  78{
  79        audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
  80        audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
  81}
  82
  83struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
  84{
  85        struct audit_fsnotify_mark *audit_mark;
  86        struct path path;
  87        struct dentry *dentry;
  88        struct inode *inode;
  89        int ret;
  90
  91        if (pathname[0] != '/' || pathname[len-1] == '/')
  92                return ERR_PTR(-EINVAL);
  93
  94        dentry = kern_path_locked(pathname, &path);
  95        if (IS_ERR(dentry))
  96                return (void *)dentry; /* returning an error */
  97        inode = path.dentry->d_inode;
  98        inode_unlock(inode);
  99
 100        audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
 101        if (unlikely(!audit_mark)) {
 102                audit_mark = ERR_PTR(-ENOMEM);
 103                goto out;
 104        }
 105
 106        fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
 107        audit_mark->mark.mask = AUDIT_FS_EVENTS;
 108        audit_mark->path = pathname;
 109        audit_update_mark(audit_mark, dentry->d_inode);
 110        audit_mark->rule = krule;
 111
 112        ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
 113        if (ret < 0) {
 114                fsnotify_put_mark(&audit_mark->mark);
 115                audit_mark = ERR_PTR(ret);
 116        }
 117out:
 118        dput(dentry);
 119        path_put(&path);
 120        return audit_mark;
 121}
 122
 123static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
 124{
 125        struct audit_buffer *ab;
 126        struct audit_krule *rule = audit_mark->rule;
 127
 128        if (!audit_enabled)
 129                return;
 130        ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
 131        if (unlikely(!ab))
 132                return;
 133        audit_log_session_info(ab);
 134        audit_log_format(ab, " op=%s path=", op);
 135        audit_log_untrustedstring(ab, audit_mark->path);
 136        audit_log_key(ab, rule->filterkey);
 137        audit_log_format(ab, " list=%d res=1", rule->listnr);
 138        audit_log_end(ab);
 139}
 140
 141void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
 142{
 143        fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
 144        fsnotify_put_mark(&audit_mark->mark);
 145}
 146
 147void audit_remove_mark_rule(struct audit_krule *krule)
 148{
 149        struct audit_fsnotify_mark *mark = krule->exe;
 150
 151        audit_remove_mark(mark);
 152}
 153
 154static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
 155{
 156        struct audit_krule *rule = audit_mark->rule;
 157        struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
 158
 159        audit_mark_log_rule_change(audit_mark, "autoremove_rule");
 160        audit_del_rule(entry);
 161}
 162
 163/* Update mark data in audit rules based on fsnotify events. */
 164static int audit_mark_handle_event(struct fsnotify_group *group,
 165                                    struct inode *to_tell,
 166                                    u32 mask, const void *data, int data_type,
 167                                    const struct qstr *dname, u32 cookie,
 168                                    struct fsnotify_iter_info *iter_info)
 169{
 170        struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
 171        struct audit_fsnotify_mark *audit_mark;
 172        const struct inode *inode = NULL;
 173
 174        audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
 175
 176        BUG_ON(group != audit_fsnotify_group);
 177
 178        switch (data_type) {
 179        case (FSNOTIFY_EVENT_PATH):
 180                inode = ((const struct path *)data)->dentry->d_inode;
 181                break;
 182        case (FSNOTIFY_EVENT_INODE):
 183                inode = (const struct inode *)data;
 184                break;
 185        default:
 186                BUG();
 187                return 0;
 188        }
 189
 190        if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
 191                if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
 192                        return 0;
 193                audit_update_mark(audit_mark, inode);
 194        } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
 195                audit_autoremove_mark_rule(audit_mark);
 196
 197        return 0;
 198}
 199
 200static const struct fsnotify_ops audit_mark_fsnotify_ops = {
 201        .handle_event = audit_mark_handle_event,
 202        .free_mark = audit_fsnotify_free_mark,
 203};
 204
 205static int __init audit_fsnotify_init(void)
 206{
 207        audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
 208        if (IS_ERR(audit_fsnotify_group)) {
 209                audit_fsnotify_group = NULL;
 210                audit_panic("cannot create audit fsnotify group");
 211        }
 212        return 0;
 213}
 214device_initcall(audit_fsnotify_init);
 215