--- /dev/null
+/* audit_watch.c -- watching inodes
+ *
+ * Copyright 2003-2009 Red Hat, Inc.
+ * Copyright 2005 Hewlett-Packard Development Company, L.P.
+ * Copyright 2005 IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/audit.h>
+#include <linux/kthread.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/fsnotify_backend.h>
+#include <linux/namei.h>
+#include <linux/netlink.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include "audit.h"
+
+/*
+ * Reference counting:
+ *
+ * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED
+ * event. Each audit_watch holds a reference to its associated parent.
+ *
+ * audit_watch: if added to lists, lifetime is from audit_init_watch() to
+ * audit_remove_watch(). Additionally, an audit_watch may exist
+ * temporarily to assist in searching existing filter data. Each
+ * audit_krule holds a reference to its associated watch.
+ */
+
+struct audit_watch {
+ atomic_t count; /* reference count */
+ dev_t dev; /* associated superblock device */
+ char *path; /* insertion path */
+ unsigned long ino; /* associated inode number */
+ struct audit_parent *parent; /* associated parent */
+ struct list_head wlist; /* entry in parent->watches list */
+ struct list_head rules; /* anchor for krule->rlist */
+};
+
+struct audit_parent {
+ struct list_head watches; /* anchor for audit_watch->wlist */
+ struct fsnotify_mark mark; /* fsnotify mark on the inode */
+};
+
+/* fsnotify handle. */
+static struct fsnotify_group *audit_watch_group;
+
+/* fsnotify events we care about. */
+#define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
+ FS_MOVE_SELF | FS_EVENT_ON_CHILD)
+
+static void audit_free_parent(struct audit_parent *parent)
+{
+ WARN_ON(!list_empty(&parent->watches));
+ kfree(parent);
+}
+
+static void audit_watch_free_mark(struct fsnotify_mark *entry)
+{
+ struct audit_parent *parent;
+
+ parent = container_of(entry, struct audit_parent, mark);
+ audit_free_parent(parent);
+}
+
+static void audit_get_parent(struct audit_parent *parent)
+{
+ if (likely(parent))
+ fsnotify_get_mark(&parent->mark);
+}
+
+static void audit_put_parent(struct audit_parent *parent)
+{
+ if (likely(parent))
+ fsnotify_put_mark(&parent->mark);
+}
+
+/*
+ * Find and return the audit_parent on the given inode. If found a reference
+ * is taken on this parent.
+ */
+static inline struct audit_parent *audit_find_parent(struct inode *inode)
+{
+ struct audit_parent *parent = NULL;
+ struct fsnotify_mark *entry;
+
+ entry = fsnotify_find_inode_mark(audit_watch_group, inode);
+ if (entry)
+ parent = container_of(entry, struct audit_parent, mark);
+
+ return parent;
+}
+
+void audit_get_watch(struct audit_watch *watch)
+{
+ atomic_inc(&watch->count);
+}
+
+void audit_put_watch(struct audit_watch *watch)
+{
+ if (atomic_dec_and_test(&watch->count)) {
+ WARN_ON(watch->parent);
+ WARN_ON(!list_empty(&watch->rules));
+ kfree(watch->path);
+ kfree(watch);
+ }
+}
+
+static void audit_remove_watch(struct audit_watch *watch)
+{
+ list_del(&watch->wlist);
+ audit_put_parent(watch->parent);
+ watch->parent = NULL;
+ audit_put_watch(watch); /* match initial get */
+}
+
+char *audit_watch_path(struct audit_watch *watch)
+{
+ return watch->path;
+}
+
+int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
+{
+ return (watch->ino != (unsigned long)-1) &&
+ (watch->ino == ino) &&
+ (watch->dev == dev);
+}
+
+/* Initialize a parent watch entry. */
+static struct audit_parent *audit_init_parent(struct path *path)
+{
+ struct inode *inode = d_backing_inode(path->dentry);
+ struct audit_parent *parent;
+ int ret;
+
+ parent = kzalloc(sizeof(*parent), GFP_KERNEL);
+ if (unlikely(!parent))
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&parent->watches);
+
+ fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
+ parent->mark.mask = AUDIT_FS_WATCH;
+ ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0);
+ if (ret < 0) {
+ audit_free_parent(parent);
+ return ERR_PTR(ret);
+ }
+
+ return parent;
+}
+
+/* Initialize a watch entry. */
+static struct audit_watch *audit_init_watch(char *path)
+{
+ struct audit_watch *watch;
+
+ watch = kzalloc(sizeof(*watch), GFP_KERNEL);
+ if (unlikely(!watch))
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&watch->rules);
+ atomic_set(&watch->count, 1);
+ watch->path = path;
+ watch->dev = (dev_t)-1;
+ watch->ino = (unsigned long)-1;
+
+ return watch;
+}
+
+/* Translate a watch string to kernel respresentation. */
+int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
+{
+ struct audit_watch *watch;
+
+ if (!audit_watch_group)
+ return -EOPNOTSUPP;
+
+ if (path[0] != '/' || path[len-1] == '/' ||
+ krule->listnr != AUDIT_FILTER_EXIT ||
+ op != Audit_equal ||
+ krule->inode_f || krule->watch || krule->tree)
+ return -EINVAL;
+
+ watch = audit_init_watch(path);
+ if (IS_ERR(watch))
+ return PTR_ERR(watch);
+
+ audit_get_watch(watch);
+ krule->watch = watch;
+
+ return 0;
+}
+
+/* Duplicate the given audit watch. The new watch's rules list is initialized
+ * to an empty list and wlist is undefined. */
+static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
+{
+ char *path;
+ struct audit_watch *new;
+
+ path = kstrdup(old->path, GFP_KERNEL);
+ if (unlikely(!path))
+ return ERR_PTR(-ENOMEM);
+
+ new = audit_init_watch(path);
+ if (IS_ERR(new)) {
+ kfree(path);
+ goto out;
+ }
+
+ new->dev = old->dev;
+ new->ino = old->ino;
+ audit_get_parent(old->parent);
+ new->parent = old->parent;
+
+out:
+ return new;
+}
+
+static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
+{
+ if (audit_enabled) {
+ struct audit_buffer *ab;
+ ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return;
+ audit_log_format(ab, "auid=%u ses=%u op=",
+ from_kuid(&init_user_ns, audit_get_loginuid(current)),
+ audit_get_sessionid(current));
+ audit_log_string(ab, op);
+ audit_log_format(ab, " path=");
+ audit_log_untrustedstring(ab, w->path);
+ audit_log_key(ab, r->filterkey);
+ audit_log_format(ab, " list=%d res=1", r->listnr);
+ audit_log_end(ab);
+ }
+}
+
+/* Update inode info in audit rules based on filesystem event. */
+static void audit_update_watch(struct audit_parent *parent,
+ const char *dname, dev_t dev,
+ unsigned long ino, unsigned invalidating)
+{
+ struct audit_watch *owatch, *nwatch, *nextw;
+ struct audit_krule *r, *nextr;
+ struct audit_entry *oentry, *nentry;
+
+ mutex_lock(&audit_filter_mutex);
+ /* Run all of the watches on this parent looking for the one that
+ * matches the given dname */
+ list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
+ if (audit_compare_dname_path(dname, owatch->path,
+ AUDIT_NAME_FULL))
+ continue;
+
+ /* If the update involves invalidating rules, do the inode-based
+ * filtering now, so we don't omit records. */
+ if (invalidating && !audit_dummy_context())
+ audit_filter_inodes(current, current->audit_context);
+
+ /* updating ino will likely change which audit_hash_list we
+ * are on so we need a new watch for the new list */
+ nwatch = audit_dupe_watch(owatch);
+ if (IS_ERR(nwatch)) {
+ mutex_unlock(&audit_filter_mutex);
+ audit_panic("error updating watch, skipping");
+ return;
+ }
+ nwatch->dev = dev;
+ nwatch->ino = ino;
+
+ list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
+
+ oentry = container_of(r, struct audit_entry, rule);
+ list_del(&oentry->rule.rlist);
+ list_del_rcu(&oentry->list);
+
+ nentry = audit_dupe_rule(&oentry->rule);
+ if (IS_ERR(nentry)) {
+ list_del(&oentry->rule.list);
+ audit_panic("error updating watch, removing");
+ } else {
+ int h = audit_hash_ino((u32)ino);
+
+ /*
+ * nentry->rule.watch == oentry->rule.watch so
+ * we must drop that reference and set it to our
+ * new watch.
+ */
+ audit_put_watch(nentry->rule.watch);
+ audit_get_watch(nwatch);
+ nentry->rule.watch = nwatch;
+ list_add(&nentry->rule.rlist, &nwatch->rules);
+ list_add_rcu(&nentry->list, &audit_inode_hash[h]);
+ list_replace(&oentry->rule.list,
+ &nentry->rule.list);
+ }
+
+ audit_watch_log_rule_change(r, owatch, "updated_rules");
+
+ call_rcu(&oentry->rcu, audit_free_rule_rcu);
+ }
+
+ audit_remove_watch(owatch);
+ goto add_watch_to_parent; /* event applies to a single watch */
+ }
+ mutex_unlock(&audit_filter_mutex);
+ return;
+
+add_watch_to_parent:
+ list_add(&nwatch->wlist, &parent->watches);
+ mutex_unlock(&audit_filter_mutex);
+ return;
+}
+
+/* Remove all watches & rules associated with a parent that is going away. */
+static void audit_remove_parent_watches(struct audit_parent *parent)
+{
+ struct audit_watch *w, *nextw;
+ struct audit_krule *r, *nextr;
+ struct audit_entry *e;
+
+ mutex_lock(&audit_filter_mutex);
+ list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
+ list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
+ e = container_of(r, struct audit_entry, rule);
+ audit_watch_log_rule_change(r, w, "remove_rule");
+ list_del(&r->rlist);
+ list_del(&r->list);
+ list_del_rcu(&e->list);
+ call_rcu(&e->rcu, audit_free_rule_rcu);
+ }
+ audit_remove_watch(w);
+ }
+ mutex_unlock(&audit_filter_mutex);
+
+ fsnotify_destroy_mark(&parent->mark, audit_watch_group);
+}
+
+/* Get path information necessary for adding watches. */
+static int audit_get_nd(struct audit_watch *watch, struct path *parent)
+{
+ struct dentry *d = kern_path_locked(watch->path, parent);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+ mutex_unlock(&d_backing_inode(parent->dentry)->i_mutex);
+ if (d_is_positive(d)) {
+ /* update watch filter fields */
+ watch->dev = d_backing_inode(d)->i_sb->s_dev;
+ watch->ino = d_backing_inode(d)->i_ino;
+ }
+ dput(d);
+ return 0;
+}
+
+/* Associate the given rule with an existing parent.
+ * Caller must hold audit_filter_mutex. */
+static void audit_add_to_parent(struct audit_krule *krule,
+ struct audit_parent *parent)
+{
+ struct audit_watch *w, *watch = krule->watch;
+ int watch_found = 0;
+
+ BUG_ON(!mutex_is_locked(&audit_filter_mutex));
+
+ list_for_each_entry(w, &parent->watches, wlist) {
+ if (strcmp(watch->path, w->path))
+ continue;
+
+ watch_found = 1;
+
+ /* put krule's and initial refs to temporary watch */
+ audit_put_watch(watch);
+ audit_put_watch(watch);
+
+ audit_get_watch(w);
+ krule->watch = watch = w;
+ break;
+ }
+
+ if (!watch_found) {
+ audit_get_parent(parent);
+ watch->parent = parent;
+
+ list_add(&watch->wlist, &parent->watches);
+ }
+ list_add(&krule->rlist, &watch->rules);
+}
+
+/* Find a matching watch entry, or add this one.
+ * Caller must hold audit_filter_mutex. */
+int audit_add_watch(struct audit_krule *krule, struct list_head **list)
+{
+ struct audit_watch *watch = krule->watch;
+ struct audit_parent *parent;
+ struct path parent_path;
+ int h, ret = 0;
+
+ mutex_unlock(&audit_filter_mutex);
+
+ /* Avoid calling path_lookup under audit_filter_mutex. */
+ ret = audit_get_nd(watch, &parent_path);
+
+ /* caller expects mutex locked */
+ mutex_lock(&audit_filter_mutex);
+
+ if (ret)
+ return ret;
+
+ /* either find an old parent or attach a new one */
+ parent = audit_find_parent(d_backing_inode(parent_path.dentry));
+ if (!parent) {
+ parent = audit_init_parent(&parent_path);
+ if (IS_ERR(parent)) {
+ ret = PTR_ERR(parent);
+ goto error;
+ }
+ }
+
+ audit_add_to_parent(krule, parent);
+
+ /* match get in audit_find_parent or audit_init_parent */
+ audit_put_parent(parent);
+
+ h = audit_hash_ino((u32)watch->ino);
+ *list = &audit_inode_hash[h];
+error:
+ path_put(&parent_path);
+ return ret;
+}
+
+void audit_remove_watch_rule(struct audit_krule *krule)
+{
+ struct audit_watch *watch = krule->watch;
+ struct audit_parent *parent = watch->parent;
+
+ list_del(&krule->rlist);
+
+ if (list_empty(&watch->rules)) {
+ audit_remove_watch(watch);
+
+ if (list_empty(&parent->watches)) {
+ audit_get_parent(parent);
+ fsnotify_destroy_mark(&parent->mark, audit_watch_group);
+ audit_put_parent(parent);
+ }
+ }
+}
+
+/* Update watch data in audit rules based on fsnotify events. */
+static int audit_watch_handle_event(struct fsnotify_group *group,
+ struct inode *to_tell,
+ struct fsnotify_mark *inode_mark,
+ struct fsnotify_mark *vfsmount_mark,
+ u32 mask, void *data, int data_type,
+ const unsigned char *dname, u32 cookie)
+{
+ struct inode *inode;
+ struct audit_parent *parent;
+
+ parent = container_of(inode_mark, struct audit_parent, mark);
+
+ BUG_ON(group != audit_watch_group);
+
+ switch (data_type) {
+ case (FSNOTIFY_EVENT_PATH):
+ inode = d_backing_inode(((struct path *)data)->dentry);
+ break;
+ case (FSNOTIFY_EVENT_INODE):
+ inode = (struct inode *)data;
+ break;
+ default:
+ BUG();
+ inode = NULL;
+ break;
+ };
+
+ if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
+ audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
+ else if (mask & (FS_DELETE|FS_MOVED_FROM))
+ audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
+ else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
+ audit_remove_parent_watches(parent);
+
+ return 0;
+}
+
+static const struct fsnotify_ops audit_watch_fsnotify_ops = {
+ .handle_event = audit_watch_handle_event,
+};
+
+static int __init audit_watch_init(void)
+{
+ audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops);
+ if (IS_ERR(audit_watch_group)) {
+ audit_watch_group = NULL;
+ audit_panic("cannot create audit fsnotify group");
+ }
+ return 0;
+}
+device_initcall(audit_watch_init);
Code Review / kvmfornfv.git / blobdiff