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Commit 28a3a7eb authored by Eric Paris's avatar Eric Paris
Browse files

audit: reimplement audit_trees using fsnotify rather than inotify 



Simply switch audit_trees from using inotify to using fsnotify for it's
inode pinning and disappearing act information.

Signed-off-by: default avatarEric Paris <eparis@redhat.com>
parent 40554c3d

include/linux/fsnotify_backend.h

+3 −2
Original line number Diff line number Diff line
@@ -63,7 +63,8 @@ 
/* listeners that hard code group numbers near the top */

#define DNOTIFY_GROUP_NUM	UINT_MAX

#define AUDIT_WATCH_GROUP_NUM	(DNOTIFY_GROUP_NUM-1)

#define INOTIFY_GROUP_NUM      (AUDIT_WATCH_GROUP_NUM-1)

#define AUDIT_TREE_GROUP_NUM	(AUDIT_WATCH_GROUP_NUM-1)

#define INOTIFY_GROUP_NUM	(AUDIT_TREE_GROUP_NUM-1)



struct fsnotify_group;

struct fsnotify_event;

init/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -326,7 +326,7 @@ config AUDITSYSCALL 
config AUDIT_TREE

	def_bool y

	depends on AUDITSYSCALL

	select INOTIFY

	select FSNOTIFY



menu "RCU Subsystem"

kernel/audit_tree.c

+130 −104
Original line number Diff line number Diff line 
#include "audit.h"

#include <linux/inotify.h>

#include <linux/fsnotify_backend.h>

#include <linux/namei.h>

#include <linux/mount.h>

#include <linux/kthread.h>
@@ -22,7 +22,7 @@ struct audit_tree { 


struct audit_chunk {

	struct list_head hash;

	struct inotify_watch watch;

	struct fsnotify_mark_entry mark;

	struct list_head trees;		/* with root here */

	int dead;

	int count;
@@ -59,7 +59,7 @@ static LIST_HEAD(prune_list); 
 * tree is refcounted; one reference for "some rules on rules_list refer to

 * it", one for each chunk with pointer to it.

 *

 * chunk is refcounted by embedded inotify_watch + .refs (non-zero refcount

 * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount

 * of watch contributes 1 to .refs).

 *

 * node.index allows to get from node.list to containing chunk.
@@ -68,7 +68,7 @@ static LIST_HEAD(prune_list); 
 * that makes a difference.  Some.

 */



static struct inotify_handle *rtree_ih;

static struct fsnotify_group *audit_tree_group;



static struct audit_tree *alloc_tree(const char *s)

{
@@ -111,29 +111,6 @@ const char *audit_tree_path(struct audit_tree *tree) 
	return tree->pathname;

}



static struct audit_chunk *alloc_chunk(int count)

{

	struct audit_chunk *chunk;

	size_t size;

	int i;



	size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);

	chunk = kzalloc(size, GFP_KERNEL);

	if (!chunk)

		return NULL;



	INIT_LIST_HEAD(&chunk->hash);

	INIT_LIST_HEAD(&chunk->trees);

	chunk->count = count;

	atomic_long_set(&chunk->refs, 1);

	for (i = 0; i < count; i++) {

		INIT_LIST_HEAD(&chunk->owners[i].list);

		chunk->owners[i].index = i;

	}

	inotify_init_watch(&chunk->watch);

	return chunk;

}



static void free_chunk(struct audit_chunk *chunk)

{

	int i;
@@ -157,6 +134,35 @@ static void __put_chunk(struct rcu_head *rcu) 
	audit_put_chunk(chunk);

}



static void audit_tree_destroy_watch(struct fsnotify_mark_entry *entry)

{

	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);

	call_rcu(&chunk->head, __put_chunk);

}



static struct audit_chunk *alloc_chunk(int count)

{

	struct audit_chunk *chunk;

	size_t size;

	int i;



	size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);

	chunk = kzalloc(size, GFP_KERNEL);

	if (!chunk)

		return NULL;



	INIT_LIST_HEAD(&chunk->hash);

	INIT_LIST_HEAD(&chunk->trees);

	chunk->count = count;

	atomic_long_set(&chunk->refs, 1);

	for (i = 0; i < count; i++) {

		INIT_LIST_HEAD(&chunk->owners[i].list);

		chunk->owners[i].index = i;

	}

	fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);

	return chunk;

}



enum {HASH_SIZE = 128};

static struct list_head chunk_hash_heads[HASH_SIZE];

static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
@@ -167,10 +173,15 @@ static inline struct list_head *chunk_hash(const struct inode *inode) 
	return chunk_hash_heads + n % HASH_SIZE;

}



/* hash_lock is held by caller */

/* hash_lock & entry->lock is held by caller */

static void insert_hash(struct audit_chunk *chunk)

{

	struct list_head *list = chunk_hash(chunk->watch.inode);

	struct fsnotify_mark_entry *entry = &chunk->mark;

	struct list_head *list;



	if (!entry->inode)

		return;

	list = chunk_hash(entry->inode);

	list_add_rcu(&chunk->hash, list);

}
@@ -181,7 +192,8 @@ struct audit_chunk *audit_tree_lookup(const struct inode *inode) 
	struct audit_chunk *p;



	list_for_each_entry_rcu(p, list, hash) {

		if (p->watch.inode == inode) {

		/* mark.inode may have gone NULL, but who cares? */

		if (p->mark.inode == inode) {

			atomic_long_inc(&p->refs);

			return p;

		}
@@ -210,38 +222,19 @@ static struct audit_chunk *find_chunk(struct node *p) 
static void untag_chunk(struct node *p)

{

	struct audit_chunk *chunk = find_chunk(p);

	struct fsnotify_mark_entry *entry = &chunk->mark;

	struct audit_chunk *new;

	struct audit_tree *owner;

	int size = chunk->count - 1;

	int i, j;



	if (!pin_inotify_watch(&chunk->watch)) {

		/*

		 * Filesystem is shutting down; all watches are getting

		 * evicted, just take it off the node list for this

		 * tree and let the eviction logics take care of the

		 * rest.

		 */

		owner = p->owner;

		if (owner->root == chunk) {

			list_del_init(&owner->same_root);

			owner->root = NULL;

		}

		list_del_init(&p->list);

		p->owner = NULL;

		put_tree(owner);

		return;

	}

	fsnotify_get_mark(entry);



	spin_unlock(&hash_lock);



	/*

	 * pin_inotify_watch() succeeded, so the watch won't go away

	 * from under us.

	 */

	mutex_lock(&chunk->watch.inode->inotify_mutex);

	if (chunk->dead) {

		mutex_unlock(&chunk->watch.inode->inotify_mutex);

	spin_lock(&entry->lock);

	if (chunk->dead || !entry->inode) {

		spin_unlock(&entry->lock);

		goto out;

	}
@@ -256,16 +249,17 @@ static void untag_chunk(struct node *p) 
		list_del_init(&p->list);

		list_del_rcu(&chunk->hash);

		spin_unlock(&hash_lock);

		inotify_evict_watch(&chunk->watch);

		mutex_unlock(&chunk->watch.inode->inotify_mutex);

		put_inotify_watch(&chunk->watch);

		spin_unlock(&entry->lock);

		fsnotify_destroy_mark_by_entry(entry);

		fsnotify_put_mark(entry);

		goto out;

	}



	new = alloc_chunk(size);

	if (!new)

		goto Fallback;

	if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {

	fsnotify_duplicate_mark(&new->mark, entry);

	if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, 1)) {

		free_chunk(new);

		goto Fallback;

	}
@@ -298,9 +292,9 @@ static void untag_chunk(struct node *p) 
	list_for_each_entry(owner, &new->trees, same_root)

		owner->root = new;

	spin_unlock(&hash_lock);

	inotify_evict_watch(&chunk->watch);

	mutex_unlock(&chunk->watch.inode->inotify_mutex);

	put_inotify_watch(&chunk->watch);

	spin_unlock(&entry->lock);

	fsnotify_destroy_mark_by_entry(entry);

	fsnotify_put_mark(entry);

	goto out;



Fallback:
@@ -314,31 +308,33 @@ static void untag_chunk(struct node *p) 
	p->owner = NULL;

	put_tree(owner);

	spin_unlock(&hash_lock);

	mutex_unlock(&chunk->watch.inode->inotify_mutex);

	spin_unlock(&entry->lock);

out:

	unpin_inotify_watch(&chunk->watch);

	fsnotify_put_mark(entry);

	spin_lock(&hash_lock);

}



static int create_chunk(struct inode *inode, struct audit_tree *tree)

{

	struct fsnotify_mark_entry *entry;

	struct audit_chunk *chunk = alloc_chunk(1);

	if (!chunk)

		return -ENOMEM;



	if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {

	entry = &chunk->mark;

	if (fsnotify_add_mark(entry, audit_tree_group, inode, 0)) {

		free_chunk(chunk);

		return -ENOSPC;

	}



	mutex_lock(&inode->inotify_mutex);

	spin_lock(&entry->lock);

	spin_lock(&hash_lock);

	if (tree->goner) {

		spin_unlock(&hash_lock);

		chunk->dead = 1;

		inotify_evict_watch(&chunk->watch);

		mutex_unlock(&inode->inotify_mutex);

		put_inotify_watch(&chunk->watch);

		spin_unlock(&entry->lock);

		fsnotify_destroy_mark_by_entry(entry);

		fsnotify_put_mark(entry);

		return 0;

	}

	chunk->owners[0].index = (1U << 31);
@@ -351,30 +347,33 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree) 
	}

	insert_hash(chunk);

	spin_unlock(&hash_lock);

	mutex_unlock(&inode->inotify_mutex);

	spin_unlock(&entry->lock);

	return 0;

}



/* the first tagged inode becomes root of tree */

static int tag_chunk(struct inode *inode, struct audit_tree *tree)

{

	struct inotify_watch *watch;

	struct fsnotify_mark_entry *old_entry, *chunk_entry;

	struct audit_tree *owner;

	struct audit_chunk *chunk, *old;

	struct node *p;

	int n;



	if (inotify_find_watch(rtree_ih, inode, &watch) < 0)

	spin_lock(&inode->i_lock);

	old_entry = fsnotify_find_mark_entry(audit_tree_group, inode);

	spin_unlock(&inode->i_lock);

	if (!old_entry)

		return create_chunk(inode, tree);



	old = container_of(watch, struct audit_chunk, watch);

	old = container_of(old_entry, struct audit_chunk, mark);



	/* are we already there? */

	spin_lock(&hash_lock);

	for (n = 0; n < old->count; n++) {

		if (old->owners[n].owner == tree) {

			spin_unlock(&hash_lock);

			put_inotify_watch(&old->watch);

			fsnotify_put_mark(old_entry);

			return 0;

		}

	}
@@ -382,25 +381,44 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) 


	chunk = alloc_chunk(old->count + 1);

	if (!chunk) {

		put_inotify_watch(&old->watch);

		fsnotify_put_mark(old_entry);

		return -ENOMEM;

	}



	mutex_lock(&inode->inotify_mutex);

	if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {

		mutex_unlock(&inode->inotify_mutex);

		put_inotify_watch(&old->watch);

	chunk_entry = &chunk->mark;



	spin_lock(&old_entry->lock);

	if (!old_entry->inode) {

		/* old_entry is being shot, lets just lie */

		spin_unlock(&old_entry->lock);

		fsnotify_put_mark(old_entry);

		free_chunk(chunk);

		return -ENOENT;

	}



	fsnotify_duplicate_mark(chunk_entry, old_entry);

	if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, 1)) {

		spin_unlock(&old_entry->lock);

		free_chunk(chunk);

		fsnotify_put_mark(old_entry);

		return -ENOSPC;

	}



	/* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */

	spin_lock(&chunk_entry->lock);

	spin_lock(&hash_lock);



	/* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */

	if (tree->goner) {

		spin_unlock(&hash_lock);

		chunk->dead = 1;

		inotify_evict_watch(&chunk->watch);

		mutex_unlock(&inode->inotify_mutex);

		put_inotify_watch(&old->watch);

		put_inotify_watch(&chunk->watch);

		spin_unlock(&chunk_entry->lock);

		spin_unlock(&old_entry->lock);



		fsnotify_destroy_mark_by_entry(chunk_entry);



		fsnotify_put_mark(chunk_entry);

		fsnotify_put_mark(old_entry);

		return 0;

	}

	list_replace_init(&old->trees, &chunk->trees);
@@ -426,10 +444,11 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) 
		list_add(&tree->same_root, &chunk->trees);

	}

	spin_unlock(&hash_lock);

	inotify_evict_watch(&old->watch);

	mutex_unlock(&inode->inotify_mutex);

	put_inotify_watch(&old->watch); /* pair to inotify_find_watch */

	put_inotify_watch(&old->watch); /* and kill it */

	spin_unlock(&chunk_entry->lock);

	spin_unlock(&old_entry->lock);

	fsnotify_destroy_mark_by_entry(old_entry);

	fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */

	fsnotify_put_mark(old_entry); /* and kill it */

	return 0;

}
@@ -584,7 +603,9 @@ void audit_trim_trees(void) 


		spin_lock(&hash_lock);

		list_for_each_entry(node, &tree->chunks, list) {

			struct inode *inode = find_chunk(node)->watch.inode;

			struct audit_chunk *chunk = find_chunk(node);

			/* this could be NULL if the watch is dieing else where... */

			struct inode *inode = chunk->mark.inode;

			node->index |= 1U<<31;

			if (iterate_mounts(compare_root, inode, root_mnt))

				node->index &= ~(1U<<31);
@@ -846,7 +867,6 @@ void audit_kill_trees(struct list_head *list) 
 *  Here comes the stuff asynchronous to auditctl operations

 */



/* inode->inotify_mutex is locked */

static void evict_chunk(struct audit_chunk *chunk)

{

	struct audit_tree *owner;
@@ -885,35 +905,41 @@ static void evict_chunk(struct audit_chunk *chunk) 
	mutex_unlock(&audit_filter_mutex);

}



static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,

                         u32 cookie, const char *dname, struct inode *inode)

static int audit_tree_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)

{

	struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);

	BUG();

	return -EOPNOTSUPP;

}



static void audit_tree_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)

{

	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);



	if (mask & IN_IGNORED) {

	evict_chunk(chunk);

		put_inotify_watch(watch);

	}

	fsnotify_put_mark(entry);

}



static void destroy_watch(struct inotify_watch *watch)

static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)

{

	struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);

	call_rcu(&chunk->head, __put_chunk);

	return 0;

}



static const struct inotify_operations rtree_inotify_ops = {

	.handle_event	= handle_event,

	.destroy_watch	= destroy_watch,

static const struct fsnotify_ops audit_tree_ops = {

	.handle_event = audit_tree_handle_event,

	.should_send_event = audit_tree_send_event,

	.free_group_priv = NULL,

	.free_event_priv = NULL,

	.freeing_mark = audit_tree_freeing_mark,

};



static int __init audit_tree_init(void)

{

	int i;



	rtree_ih = inotify_init(&rtree_inotify_ops);

	if (IS_ERR(rtree_ih))

		audit_panic("cannot initialize inotify handle for rectree watches");

	audit_tree_group = fsnotify_obtain_group(AUDIT_TREE_GROUP_NUM,

						 0, &audit_tree_ops);

	if (IS_ERR(audit_tree_group))

		audit_panic("cannot initialize fsnotify group for rectree watches");



	for (i = 0; i < HASH_SIZE; i++)

		INIT_LIST_HEAD(&chunk_hash_heads[i]);

kernel/auditsc.c

+2 −2
Original line number Diff line number Diff line
@@ -1725,7 +1725,7 @@ static inline void handle_one(const struct inode *inode) 
	struct audit_tree_refs *p;

	struct audit_chunk *chunk;

	int count;

	if (likely(list_empty(&inode->inotify_watches)))

	if (likely(hlist_empty(&inode->i_fsnotify_mark_entries)))

		return;

	context = current->audit_context;

	p = context->trees;
@@ -1768,7 +1768,7 @@ static void handle_path(const struct dentry *dentry) 
	seq = read_seqbegin(&rename_lock);

	for(;;) {

		struct inode *inode = d->d_inode;

		if (inode && unlikely(!list_empty(&inode->inotify_watches))) {

		if (inode && unlikely(!hlist_empty(&inode->i_fsnotify_mark_entries))) {

			struct audit_chunk *chunk;

			chunk = audit_tree_lookup(inode);

			if (chunk) {