[PATCH 09/14] audit: Allocate fsnotify mark independently of chunk

Jan Kara
2018-10-17T10:15:00Z

Allocate fsnotify mark independently instead of embedding it inside
chunk. This will allow us to just replace chunk attached to mark when
growing / shrinking chunk instead of replacing mark attached to inode
which is a more complex operation.

Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
kernel/audit_tree.c | 64 +++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 50 insertions(+), 14 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 35c031ebcc12..c98ab2d68a1c 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -25,7 +25,7 @@ struct audit_tree {
struct audit_chunk {
struct list_head hash;
unsigned long key;
- struct fsnotify_mark mark;
+ struct fsnotify_mark *mark;
struct list_head trees; /* with root here */
int dead;
int count;
@@ -38,6 +38,11 @@ struct audit_chunk {
} owners[];
};

+struct audit_tree_mark {
+ struct fsnotify_mark mark;
+ struct audit_chunk *chunk;
+};
+
static LIST_HEAD(tree_list);
static LIST_HEAD(prune_list);
static struct task_struct *prune_thread;
@@ -73,6 +78,7 @@ static struct task_struct *prune_thread;
*/

static struct fsnotify_group *audit_tree_group;
+static struct kmem_cache *audit_tree_mark_cachep __read_mostly;

static struct audit_tree *alloc_tree(const char *s)
{
@@ -142,10 +148,33 @@ static void audit_mark_put_chunk(struct audit_chunk *chunk)
call_rcu(&chunk->head, __put_chunk);
}

+static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *entry)
+{
+ return container_of(entry, struct audit_tree_mark, mark);
+}
+
+static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
+{
+ return audit_mark(mark)->chunk;
+}
+
static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
{
- struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
+ struct audit_chunk *chunk = mark_chunk(entry);
audit_mark_put_chunk(chunk);
+ kmem_cache_free(audit_tree_mark_cachep, audit_mark(entry));
+}
+
+static struct fsnotify_mark *alloc_mark(void)
+{
+ struct audit_tree_mark *amark;
+
+ amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
+ if (!amark)
+ return NULL;
+ fsnotify_init_mark(&amark->mark, audit_tree_group);
+ amark->mark.mask = FS_IN_IGNORED;
+ return &amark->mark;
}

static struct audit_chunk *alloc_chunk(int count)
@@ -159,6 +188,13 @@ static struct audit_chunk *alloc_chunk(int count)
if (!chunk)
return NULL;

+ chunk->mark = alloc_mark();
+ if (!chunk->mark) {
+ kfree(chunk);
+ return NULL;
+ }
+ audit_mark(chunk->mark)->chunk = chunk;
+
INIT_LIST_HEAD(&chunk->hash);
INIT_LIST_HEAD(&chunk->trees);
chunk->count = count;
@@ -167,8 +203,6 @@ static struct audit_chunk *alloc_chunk(int count)
INIT_LIST_HEAD(&chunk->owners[i].list);
chunk->owners[i].index = i;
}
- fsnotify_init_mark(&chunk->mark, audit_tree_group);
- chunk->mark.mask = FS_IN_IGNORED;
return chunk;
}

@@ -278,7 +312,7 @@ static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,
static void untag_chunk(struct node *p)
{
struct audit_chunk *chunk = find_chunk(p);
- struct fsnotify_mark *entry = &chunk->mark;
+ struct fsnotify_mark *entry = chunk->mark;
struct audit_chunk *new = NULL;
struct audit_tree *owner;
int size = chunk->count - 1;
@@ -298,7 +332,7 @@ static void untag_chunk(struct node *p)
if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
mutex_unlock(&entry->group->mark_mutex);
if (new)
- fsnotify_put_mark(&new->mark);
+ fsnotify_put_mark(new->mark);
goto out;
}

@@ -322,9 +356,9 @@ static void untag_chunk(struct node *p)
if (!new)
goto Fallback;

- if (fsnotify_add_mark_locked(&new->mark, entry->connector->obj,
+ if (fsnotify_add_mark_locked(new->mark, entry->connector->obj,
FSNOTIFY_OBJ_TYPE_INODE, 1)) {
- fsnotify_put_mark(&new->mark);
+ fsnotify_put_mark(new->mark);
goto Fallback;
}

@@ -344,7 +378,7 @@ static void untag_chunk(struct node *p)
fsnotify_detach_mark(entry);
mutex_unlock(&entry->group->mark_mutex);
fsnotify_free_mark(entry);
- fsnotify_put_mark(&new->mark); /* drop initial reference */
+ fsnotify_put_mark(new->mark); /* drop initial reference */
goto out;

Fallback:
@@ -375,7 +409,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
return -ENOMEM;
}

- entry = &chunk->mark;
+ entry = chunk->mark;
if (fsnotify_add_inode_mark_locked(entry, inode, 0)) {
mutex_unlock(&audit_tree_group->mark_mutex);
fsnotify_put_mark(entry);
@@ -426,7 +460,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
if (!old_entry)
return create_chunk(inode, tree);

- old = container_of(old_entry, struct audit_chunk, mark);
+ old = mark_chunk(old_entry);

/* are we already there? */
spin_lock(&hash_lock);
@@ -447,7 +481,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
return -ENOMEM;
}

- chunk_entry = &chunk->mark;
+ chunk_entry = chunk->mark;

/*
* mark_mutex protects mark from getting detached and thus also from
@@ -457,7 +491,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
/* old_entry is being shot, lets just lie */
mutex_unlock(&audit_tree_group->mark_mutex);
fsnotify_put_mark(old_entry);
- fsnotify_put_mark(&chunk->mark);
+ fsnotify_put_mark(chunk->mark);
return -ENOENT;
}

@@ -1011,7 +1045,7 @@ static int audit_tree_handle_event(struct fsnotify_group *group,

static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
{
- struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
+ struct audit_chunk *chunk = mark_chunk(entry);

evict_chunk(chunk);

@@ -1032,6 +1066,8 @@ static int __init audit_tree_init(void)
{
int i;

+ audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
+
audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
if (IS_ERR(audit_tree_group))
audit_panic("cannot initialize fsnotify group for rectree watches");
--
2.16.4