Re: [PATCH V4 (was V6) 2/2] audit: eliminate unnecessary extra layer of watch parent references

Paul Moore
2015-08-04T22:28:05Z

On Saturday, August 01, 2015 03:41:13 PM Richard Guy Briggs wrote:
> The audit watch parent count was imbalanced, adding an unnecessary layer of
> watch parent references. Decrement the additional parent reference when a
> watch is reused, already having a reference to the parent.
>
> audit_find_parent() gets a reference to the parent, if the parent is
> already known. This additional parental reference is not needed if the
> watch is subsequently found by audit_add_to_parent(), and consumed if
> the watch does not already exist, so we need to put the parent if the
> watch is found, and do nothing if this new watch is added to the parent.
>
> If the parent wasn't already known, it is created with a refcount of 1
> and added to the audit_watch_group, then incremented by one to be
> subsequently consumed by the newly created watch in
> audit_add_to_parent().
>
> The rule points to the watch, not to the parent, so the rule's refcount
> gets bumped, not the parent's.
>
> See LKML, 2015-07-16
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
> kernel/audit_watch.c | 6 ++----
> 1 files changed, 2 insertions(+), 4 deletions(-)

Merged.

> diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
> index f33f54c..8f123d7 100644
> --- a/kernel/audit_watch.c
> +++ b/kernel/audit_watch.c
> @@ -391,11 +391,12 @@ static void audit_add_to_parent(struct audit_krule
> *krule,
>
> audit_get_watch(w);
> krule->watch = watch = w;
> +
> + audit_put_parent(parent);
> break;
> }
>
> if (!watch_found) {
> - audit_get_parent(parent);
> watch->parent = parent;
>
> audit_get_watch(watch);
> @@ -436,9 +437,6 @@ int audit_add_watch(struct audit_krule *krule, struct
> list_head **list)
>
> 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:

--
paul moore
security @ redhat