kernel/audit_fsnotify.c

   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  */
  35 struct 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. */
  44 static 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
  50 static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
  51 {
  52         kfree(audit_mark->path);
  53         kfree(audit_mark);
  54 }
  55
  56 static 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
  64 char *audit_mark_path(struct audit_fsnotify_mark *mark)
  65 {
  66         return mark->path;
  67 }
  68
  69 int 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
  76 static 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
  83 struct 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         }
 117 out:
 118         dput(dentry);
 119         path_put(&path);
 120         return audit_mark;
 121 }
 122
 123 static 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(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
 131         if (unlikely(!ab))
 132                 return;
 133         audit_log_format(ab, "auid=%u ses=%u op=%s",
 134                          from_kuid(&init_user_ns, audit_get_loginuid(current)),
 135                          audit_get_sessionid(current), op);
 136         audit_log_format(ab, " path=");
 137         audit_log_untrustedstring(ab, audit_mark->path);
 138         audit_log_key(ab, rule->filterkey);
 139         audit_log_format(ab, " list=%d res=1", rule->listnr);
 140         audit_log_end(ab);
 141 }
 142
 143 void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
 144 {
 145         fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
 146         fsnotify_put_mark(&audit_mark->mark);
 147 }
 148
 149 void audit_remove_mark_rule(struct audit_krule *krule)
 150 {
 151         struct audit_fsnotify_mark *mark = krule->exe;
 152
 153         audit_remove_mark(mark);
 154 }
 155
 156 static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
 157 {
 158         struct audit_krule *rule = audit_mark->rule;
 159         struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
 160
 161         audit_mark_log_rule_change(audit_mark, "autoremove_rule");
 162         audit_del_rule(entry);
 163 }
 164
 165 /* Update mark data in audit rules based on fsnotify events. */
 166 static int audit_mark_handle_event(struct fsnotify_group *group,
 167                                     struct inode *to_tell,
 168                                     u32 mask, const void *data, int data_type,
 169                                     const unsigned char *dname, u32 cookie,
 170                                     struct fsnotify_iter_info *iter_info)
 171 {
 172         struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
 173         struct audit_fsnotify_mark *audit_mark;
 174         const struct inode *inode = NULL;
 175
 176         audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
 177
 178         BUG_ON(group != audit_fsnotify_group);
 179
 180         switch (data_type) {
 181         case (FSNOTIFY_EVENT_PATH):
 182                 inode = ((const struct path *)data)->dentry->d_inode;
 183                 break;
 184         case (FSNOTIFY_EVENT_INODE):
 185                 inode = (const struct inode *)data;
 186                 break;
 187         default:
 188                 BUG();
 189                 return 0;
 190         }
 191
 192         if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
 193                 if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
 194                         return 0;
 195                 audit_update_mark(audit_mark, inode);
 196         } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
 197                 audit_autoremove_mark_rule(audit_mark);
 198
 199         return 0;
 200 }
 201
 202 static const struct fsnotify_ops audit_mark_fsnotify_ops = {
 203         .handle_event = audit_mark_handle_event,
 204         .free_mark = audit_fsnotify_free_mark,
 205 };
 206
 207 static int __init audit_fsnotify_init(void)
 208 {
 209         audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
 210         if (IS_ERR(audit_fsnotify_group)) {
 211                 audit_fsnotify_group = NULL;
 212                 audit_panic("cannot create audit fsnotify group");
 213         }
 214         return 0;
 215 }
 216 device_initcall(audit_fsnotify_init);