[PATCH 1/7] audit: convert audit watches to use fsnotify instead of inotify
Eric Paris
eparis at redhat.com
Fri Jun 12 20:31:59 UTC 2009
Audit currently uses inotify to pin inodes in core and to detect when
watched inodes are deleted or unmounted. This patch uses fsnotify instead
of inotify.
Signed-off-by: Eric Paris <eparis at redhat.com>
---
include/linux/fsnotify_backend.h | 5 +
kernel/audit_watch.c | 209 +++++++++++++++++++++++++++-----------
2 files changed, 153 insertions(+), 61 deletions(-)
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 44848aa..90e32cc 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -58,9 +58,12 @@
FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
FS_DELETE)
+#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
+
/* listeners that hard code group numbers near the top */
#define DNOTIFY_GROUP_NUM UINT_MAX
-#define INOTIFY_GROUP_NUM (DNOTIFY_GROUP_NUM-1)
+#define AUDIT_WATCH_GROUP_NUM (DNOTIFY_GROUP_NUM-1)
+#define INOTIFY_GROUP_NUM (AUDIT_WATCH_GROUP_NUM-1)
struct fsnotify_group;
struct fsnotify_event;
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 0c179fb..8d7f264 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -24,17 +24,17 @@
#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/inotify.h>
#include <linux/security.h>
#include "audit.h"
/*
* Reference counting:
*
- * audit_parent: lifetime is from audit_init_parent() to receipt of an IN_IGNORED
+ * 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
@@ -56,29 +56,30 @@ struct audit_watch {
struct audit_parent {
struct list_head ilist; /* tmp list used to free parents */
struct list_head watches; /* anchor for audit_watch->wlist */
- struct inotify_watch wdata; /* inotify watch data */
+ struct fsnotify_mark_entry mark; /* fsnotify mark on the inode */
unsigned flags; /* status flags */
};
static struct kmem_cache *audit_watch_cache __read_mostly;
static struct kmem_cache *audit_parent_cache __read_mostly;
-/* Inotify handle. */
-struct inotify_handle *audit_ih;
+/* fsnotify handle. */
+struct fsnotify_group *audit_watch_group;
/*
* audit_parent status flags:
*
* AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to
* a filesystem event to ensure we're adding audit watches to a valid parent.
- * Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot
- * receive them while we have nameidata, but must be used for IN_MOVE_SELF which
+ * Technically not needed for FS_DELETE_SELF or FS_UNMOUNT events, as we cannot
+ * receive them while we have nameidata, but must be used for FS_MOVE_SELF which
* we can receive while holding nameidata.
*/
#define AUDIT_PARENT_INVALID 0x001
-/* Inotify events we care about. */
-#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF
+/* 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)
{
@@ -86,14 +87,45 @@ static void audit_free_parent(struct audit_parent *parent)
kmem_cache_free(audit_parent_cache, parent);
}
-static void audit_destroy_watch(struct inotify_watch *i_watch)
+static void audit_watch_free_mark(struct fsnotify_mark_entry *entry)
{
struct audit_parent *parent;
- parent = container_of(i_watch, struct audit_parent, wdata);
+ 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;
+
+ spin_lock(&inode->i_lock);
+ entry = fsnotify_find_mark_entry(audit_watch_group, inode);
+ spin_unlock(&inode->i_lock);
+
+ if (entry)
+ parent = container_of(entry, struct audit_parent, mark);
+
+ return parent;
+}
+
void audit_get_watch(struct audit_watch *watch)
{
atomic_inc(&watch->count);
@@ -112,7 +144,7 @@ void audit_put_watch(struct audit_watch *watch)
void audit_remove_watch(struct audit_watch *watch)
{
list_del(&watch->wlist);
- put_inotify_watch(&watch->parent->wdata);
+ audit_put_parent(watch->parent);
watch->parent = NULL;
audit_put_watch(watch); /* match initial get */
}
@@ -132,8 +164,9 @@ int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
/* Initialize a parent watch entry. */
static struct audit_parent *audit_init_parent(struct path *parent_path)
{
+ struct inode *inode = parent_path->dentry->d_inode;
struct audit_parent *parent;
- s32 wd;
+ int ret;
parent = kmem_cache_zalloc(audit_parent_cache, GFP_KERNEL);
if (unlikely(!parent))
@@ -142,14 +175,14 @@ static struct audit_parent *audit_init_parent(struct path *parent_path)
INIT_LIST_HEAD(&parent->watches);
parent->flags = 0;
- inotify_init_watch(&parent->wdata);
- /* grab a ref so inotify watch hangs around until we take audit_filter_mutex */
- get_inotify_watch(&parent->wdata);
- wd = inotify_add_watch(audit_ih, &parent->wdata,
- parent_path->dentry->d_inode, AUDIT_IN_WATCH);
- if (wd < 0) {
+ fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
+ parent->mark.mask = AUDIT_FS_WATCH;
+ /* grab a ref so fsnotify mark hangs around until we take audit_filter_mutex */
+ audit_get_parent(parent);
+ ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode);
+ if (ret < 0) {
audit_free_parent(parent);
- return ERR_PTR(wd);
+ return ERR_PTR(ret);
}
return parent;
@@ -178,7 +211,7 @@ int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
{
struct audit_watch *watch;
- if (!audit_ih)
+ if (!audit_watch_group)
return -EOPNOTSUPP;
if (path[0] != '/' || path[len-1] == '/' ||
@@ -216,7 +249,7 @@ static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
new->dev = old->dev;
new->ino = old->ino;
- get_inotify_watch(&old->parent->wdata);
+ audit_get_parent(old->parent);
new->parent = old->parent;
out:
@@ -337,19 +370,21 @@ static void audit_remove_parent_watches(struct audit_parent *parent)
audit_remove_watch(w);
}
mutex_unlock(&audit_filter_mutex);
+
+ fsnotify_destroy_mark_by_entry(&parent->mark);
}
/* Unregister inotify watches for parents on in_list.
- * Generates an IN_IGNORED event. */
+ * Generates an FS_IGNORED event. */
void audit_watch_inotify_unregister(struct list_head *in_list)
{
struct audit_parent *p, *n;
list_for_each_entry_safe(p, n, in_list, ilist) {
list_del(&p->ilist);
- inotify_rm_watch(audit_ih, &p->wdata);
- /* the unpin matching the pin in audit_remove_watch_rule() */
- unpin_inotify_watch(&p->wdata);
+ fsnotify_destroy_mark_by_entry(&p->mark);
+ /* matches the get in audit_remove_watch_rule() */
+ audit_put_parent(p);
}
}
@@ -383,7 +418,7 @@ static void audit_put_path(struct path *parent_path, struct path *watch_path)
path_put(watch_path);
}
-/* Associate the given rule with an existing parent inotify_watch.
+/* 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)
@@ -391,6 +426,8 @@ static void audit_add_to_parent(struct audit_krule *krule,
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;
@@ -407,7 +444,7 @@ static void audit_add_to_parent(struct audit_krule *krule,
}
if (!watch_found) {
- get_inotify_watch(&parent->wdata);
+ audit_get_parent(parent);
watch->parent = parent;
list_add(&watch->wlist, &parent->watches);
@@ -420,7 +457,6 @@ static void audit_add_to_parent(struct audit_krule *krule,
int audit_add_watch(struct audit_krule *krule, struct list_head **list)
{
struct audit_watch *watch = krule->watch;
- struct inotify_watch *i_watch;
struct audit_parent *parent;
struct path parent_path, watch_path;
int h, ret = 0;
@@ -446,8 +482,8 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list)
* inotify watch is found, inotify_find_watch() grabs a reference before
* returning.
*/
- if (inotify_find_watch(audit_ih, parent_path.dentry->d_inode,
- &i_watch) < 0) {
+ parent = audit_find_parent(parent_path.dentry->d_inode);
+ if (!parent) {
parent = audit_init_parent(&parent_path);
if (IS_ERR(parent)) {
/* caller expects mutex locked */
@@ -455,8 +491,7 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list)
ret = PTR_ERR(parent);
goto error;
}
- } else
- parent = container_of(i_watch, struct audit_parent, wdata);
+ }
mutex_lock(&audit_filter_mutex);
@@ -466,8 +501,8 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list)
else
audit_add_to_parent(krule, parent);
- /* match get in audit_init_parent or inotify_find_watch */
- put_inotify_watch(&parent->wdata);
+ /* 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];
@@ -488,54 +523,108 @@ void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list)
audit_remove_watch(watch);
if (list_empty(&parent->watches)) {
- /* Put parent on the inotify un-registration
- * list. Grab a reference before releasing
+ /* Put parent on the un-registration list.
+ * Grab a reference before releasing
* audit_filter_mutex, to be released in
- * audit_inotify_unregister().
+ * audit_watch_inotify_unregister().
* If filesystem is going away, just leave
* the sucker alone, eviction will take
* care of it. */
- if (pin_inotify_watch(&parent->wdata))
- list_add(&parent->ilist, list);
+ audit_get_parent(parent);
+ list_add(&parent->ilist, list);
}
}
}
-/* Update watch data in audit rules based on inotify events. */
-static void audit_handle_ievent(struct inotify_watch *i_watch, u32 wd, u32 mask,
- u32 cookie, const char *dname, struct inode *inode)
+static bool audit_watch_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
+{
+ struct fsnotify_mark_entry *entry;
+ bool send;
+
+ spin_lock(&inode->i_lock);
+ entry = fsnotify_find_mark_entry(group, inode);
+ spin_unlock(&inode->i_lock);
+ if (!entry)
+ return false;
+
+ mask = (mask & ~FS_EVENT_ON_CHILD);
+ send = (entry->mask & mask);
+
+ /* find took a reference */
+ fsnotify_put_mark(entry);
+
+ return send;
+}
+
+/* Update watch data in audit rules based on fsnotify events. */
+static int audit_watch_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
{
+ struct inode *inode;
+ __u32 mask = event->mask;
+ const char *dname = event->file_name;
struct audit_parent *parent;
- parent = container_of(i_watch, struct audit_parent, wdata);
+ BUG_ON(group != audit_watch_group);
+
+ parent = audit_find_parent(event->to_tell);
+ if (unlikely(!parent))
+ return 0;
- if (mask & (IN_CREATE|IN_MOVED_TO) && inode)
+ switch (event->data_type) {
+ case (FSNOTIFY_EVENT_PATH):
+ inode = event->path.dentry->d_inode;
+ break;
+ case (FSNOTIFY_EVENT_INODE):
+ inode = event->inode;
+ 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 & (IN_DELETE|IN_MOVED_FROM))
+ else if (mask & (FS_DELETE|FS_MOVED_FROM))
audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
- /* inotify automatically removes the watch and sends IN_IGNORED */
- else if (mask & (IN_DELETE_SELF|IN_UNMOUNT))
- audit_remove_parent_watches(parent);
- /* inotify does not remove the watch, so remove it manually */
- else if(mask & IN_MOVE_SELF) {
+ else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
audit_remove_parent_watches(parent);
- inotify_remove_watch_locked(audit_ih, i_watch);
- } else if (mask & IN_IGNORED)
- put_inotify_watch(i_watch);
+ /* moved put_inotify_watch to freeing mark */
+
+ /* matched the ref taken by audit_find_parent */
+ audit_put_parent(parent);
+
+ return 0;
+}
+
+static void audit_watch_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
+{
+ struct audit_parent *parent;
+
+ parent = container_of(entry, struct audit_parent, mark);
+ /* taken from audit_handle_ievent & FS_IGNORED please figure out what I match... */
+ audit_put_parent(parent);
}
-static const struct inotify_operations audit_inotify_ops = {
- .handle_event = audit_handle_ievent,
- .destroy_watch = audit_destroy_watch,
+static const struct fsnotify_ops audit_watch_fsnotify_ops = {
+ .should_send_event = audit_watch_should_send_event,
+ .handle_event = audit_watch_handle_event,
+ .free_group_priv = NULL,
+ .freeing_mark = audit_watch_freeing_mark,
+ .free_event_priv = NULL,
};
static int __init audit_watch_init(void)
{
audit_watch_cache = KMEM_CACHE(audit_watch, SLAB_PANIC);
audit_parent_cache = KMEM_CACHE(audit_parent, SLAB_PANIC);
- audit_ih = inotify_init(&audit_inotify_ops);
- if (IS_ERR(audit_ih))
- audit_panic("cannot initialize inotify handle");
+
+ audit_watch_group = fsnotify_obtain_group(AUDIT_WATCH_GROUP_NUM, AUDIT_FS_WATCH,
+ &audit_watch_fsnotify_ops);
+ if (IS_ERR(audit_watch_group)) {
+ audit_watch_group = NULL;
+ audit_panic("cannot create audit fsnotify group");
+ }
return 0;
}
subsys_initcall(audit_watch_init);
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