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Linux/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_free_mark);
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_mark(&audit_mark->mark, audit_fsnotify_group, inode, NULL, true);
113         if (ret < 0) {
114                 audit_fsnotify_mark_free(audit_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                                     struct fsnotify_mark *inode_mark,
169                                     struct fsnotify_mark *vfsmount_mark,
170                                     u32 mask, const void *data, int data_type,
171                                     const unsigned char *dname, u32 cookie)
172 {
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 };
205 
206 static int __init audit_fsnotify_init(void)
207 {
208         audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
209         if (IS_ERR(audit_fsnotify_group)) {
210                 audit_fsnotify_group = NULL;
211                 audit_panic("cannot create audit fsnotify group");
212         }
213         return 0;
214 }
215 device_initcall(audit_fsnotify_init);
216 

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