On Tue, Jul 17, 2018 at 01:54:32PM -0700, Dave Jiang wrote:
> Adding key_put_sync() that calls flush_work on key_gc_work to ensure the
> key we want to remove is gone.
>
> Signed-off-by: Dave Jiang <[email protected]>
Why is this needed? Isn't key_unlink() or key_invalidate() enough?
- Eric
> ---
> include/linux/key.h | 1 +
> security/keys/key.c | 35 +++++++++++++++++++++++++++++------
> 2 files changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/key.h b/include/linux/key.h
> index e58ee10f6e58..4dffbd23d4e4 100644
> --- a/include/linux/key.h
> +++ b/include/linux/key.h
> @@ -253,6 +253,7 @@ extern struct key *key_alloc(struct key_type *type,
> extern void key_revoke(struct key *key);
> extern void key_invalidate(struct key *key);
> extern void key_put(struct key *key);
> +extern void key_put_sync(struct key *key);
>
> static inline struct key *__key_get(struct key *key)
> {
> diff --git a/security/keys/key.c b/security/keys/key.c
> index d97c9394b5dd..b6f3ec19ab0f 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -622,6 +622,19 @@ int key_reject_and_link(struct key *key,
> }
> EXPORT_SYMBOL(key_reject_and_link);
>
> +static void __key_put(struct key *key, bool sync)
> +{
> + if (key) {
> + key_check(key);
> +
> + if (refcount_dec_and_test(&key->usage)) {
> + schedule_work(&key_gc_work);
> + if (sync)
> + flush_work(&key_gc_work);
> + }
> + }
> +}
> +
> /**
> * key_put - Discard a reference to a key.
> * @key: The key to discard a reference from.
> @@ -632,15 +645,25 @@ EXPORT_SYMBOL(key_reject_and_link);
> */
> void key_put(struct key *key)
> {
> - if (key) {
> - key_check(key);
> -
> - if (refcount_dec_and_test(&key->usage))
> - schedule_work(&key_gc_work);
> - }
> + __key_put(key, false);
> }
> EXPORT_SYMBOL(key_put);
>
> +/**
> + * key_put - Discard a reference to a key and flush the key gc work item.
> + * @key: The key to discard a reference from.
> + *
> + * Discard a reference to a key, and when all the references are gone, we
> + * schedule the cleanup task to come and pull it out of the tree in process
> + * context at some later time. This call flushes the clean up so we are sure
> + * that the key is gone.
> + */
> +void key_put_sync(struct key *key)
> +{
> + __key_put(key, true);
> +}
> +EXPORT_SYMBOL(key_put_sync);
> +
> /*
> * Find a key by its serial number.
> */
>
> --
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