kernel/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  */
  26 struct 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. */
  35 static 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
  41 static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
  42 {
  43         kfree(audit_mark->path);
  44         kfree(audit_mark);
  45 }
  46
  47 static 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
  55 char *audit_mark_path(struct audit_fsnotify_mark *mark)
  56 {
  57         return mark->path;
  58 }
  59
  60 int 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
  67 static 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
  74 struct 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         struct inode *inode;
  80         int ret;
  81
  82         if (pathname[0] != '/' || pathname[len-1] == '/')
  83                 return ERR_PTR(-EINVAL);
  84
  85         dentry = kern_path_locked(pathname, &path);
  86         if (IS_ERR(dentry))
  87                 return (void *)dentry; /* returning an error */
  88         inode = path.dentry->d_inode;
  89         inode_unlock(inode);
  90
  91         audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
  92         if (unlikely(!audit_mark)) {
  93                 audit_mark = ERR_PTR(-ENOMEM);
  94                 goto out;
  95         }
  96
  97         fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
  98         audit_mark->mark.mask = AUDIT_FS_EVENTS;
  99         audit_mark->path = pathname;
 100         audit_update_mark(audit_mark, dentry->d_inode);
 101         audit_mark->rule = krule;
 102
 103         ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
 104         if (ret < 0) {
 105                 fsnotify_put_mark(&audit_mark->mark);
 106                 audit_mark = ERR_PTR(ret);
 107         }
 108 out:
 109         dput(dentry);
 110         path_put(&path);
 111         return audit_mark;
 112 }
 113
 114 static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
 115 {
 116         struct audit_buffer *ab;
 117         struct audit_krule *rule = audit_mark->rule;
 118
 119         if (!audit_enabled)
 120                 return;
 121         ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
 122         if (unlikely(!ab))
 123                 return;
 124         audit_log_session_info(ab);
 125         audit_log_format(ab, " op=%s path=", op);
 126         audit_log_untrustedstring(ab, audit_mark->path);
 127         audit_log_key(ab, rule->filterkey);
 128         audit_log_format(ab, " list=%d res=1", rule->listnr);
 129         audit_log_end(ab);
 130 }
 131
 132 void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
 133 {
 134         fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
 135         fsnotify_put_mark(&audit_mark->mark);
 136 }
 137
 138 void audit_remove_mark_rule(struct audit_krule *krule)
 139 {
 140         struct audit_fsnotify_mark *mark = krule->exe;
 141
 142         audit_remove_mark(mark);
 143 }
 144
 145 static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
 146 {
 147         struct audit_krule *rule = audit_mark->rule;
 148         struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
 149
 150         audit_mark_log_rule_change(audit_mark, "autoremove_rule");
 151         audit_del_rule(entry);
 152 }
 153
 154 /* Update mark data in audit rules based on fsnotify events. */
 155 static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
 156                                    struct inode *inode, struct inode *dir,
 157                                    const struct qstr *dname, u32 cookie)
 158 {
 159         struct audit_fsnotify_mark *audit_mark;
 160
 161         audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
 162
 163         if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group) ||
 164             WARN_ON_ONCE(!inode))
 165                 return 0;
 166
 167         if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
 168                 if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
 169                         return 0;
 170                 audit_update_mark(audit_mark, inode);
 171         } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) {
 172                 audit_autoremove_mark_rule(audit_mark);
 173         }
 174
 175         return 0;
 176 }
 177
 178 static const struct fsnotify_ops audit_mark_fsnotify_ops = {
 179         .handle_inode_event = audit_mark_handle_event,
 180         .free_mark = audit_fsnotify_free_mark,
 181 };
 182
 183 static int __init audit_fsnotify_init(void)
 184 {
 185         audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
 186         if (IS_ERR(audit_fsnotify_group)) {
 187                 audit_fsnotify_group = NULL;
 188                 audit_panic("cannot create audit fsnotify group");
 189         }
 190         return 0;
 191 }
 192 device_initcall(audit_fsnotify_init);