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: Eric Paris <eparis@redhat.com>

1 files changed, 130 insertions, 104 deletions

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 46a57b57a335..a164600dd82e 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -1,5 +1,5 @@
 #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 @@ Fallback:
         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;
+}
 
-        if (mask & IN_IGNORED) {
-                evict_chunk(chunk);
-                put_inotify_watch(watch);
-        }
+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);
+
+        evict_chunk(chunk);
+        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]);