From 137ec390fad41928307216ea9f91acf5cf6f4204 Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Mon, 3 Aug 2020 13:16:27 +0300 Subject: [PATCH] ipc: Use generic ns_common::count Switch over ipc namespaces to use the newly introduced common lifetime counter. Currently every namespace type has its own lifetime counter which is stored in the specific namespace struct. The lifetime counters are used identically for all namespaces types. Namespaces may of course have additional unrelated counters and these are not altered. This introduces a common lifetime counter into struct ns_common. The ns_common struct encompasses information that all namespaces share. That should include the lifetime counter since its common for all of them. It also allows us to unify the type of the counters across all namespaces. Most of them use refcount_t but one uses atomic_t and at least one uses kref. Especially the last one doesn't make much sense since it's just a wrapper around refcount_t since 2016 and actually complicates cleanup operations by having to use container_of() to cast the correct namespace struct out of struct ns_common. Having the lifetime counter for the namespaces in one place reduces maintenance cost. Not just because after switching all namespaces over we will have removed more code than we added but also because the logic is more easily understandable and we indicate to the user that the basic lifetime requirements for all namespaces are currently identical. Signed-off-by: Kirill Tkhai Reviewed-by: Kees Cook Acked-by: Christian Brauner Link: https://lore.kernel.org/r/159644978697.604812.16592754423881032385.stgit@localhost.localdomain Signed-off-by: Christian Brauner --- include/linux/ipc_namespace.h | 3 +-- ipc/msgutil.c | 2 +- ipc/namespace.c | 4 ++-- 3 files changed, 4 insertions(+), 5 deletions(-) diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index a06a78c67f19..05e22770af51 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -27,7 +27,6 @@ struct ipc_ids { }; struct ipc_namespace { - refcount_t count; struct ipc_ids ids[3]; int sem_ctls[4]; @@ -128,7 +127,7 @@ extern struct ipc_namespace *copy_ipcs(unsigned long flags, static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns) { if (ns) - refcount_inc(&ns->count); + refcount_inc(&ns->ns.count); return ns; } diff --git a/ipc/msgutil.c b/ipc/msgutil.c index 3149b4a379de..d0a0e877cadd 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -26,7 +26,7 @@ DEFINE_SPINLOCK(mq_lock); * and not CONFIG_IPC_NS. */ struct ipc_namespace init_ipc_ns = { - .count = REFCOUNT_INIT(1), + .ns.count = REFCOUNT_INIT(1), .user_ns = &init_user_ns, .ns.inum = PROC_IPC_INIT_INO, #ifdef CONFIG_IPC_NS diff --git a/ipc/namespace.c b/ipc/namespace.c index 24e7b45320f7..7bd0766ddc3b 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -51,7 +51,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns, goto fail_free; ns->ns.ops = &ipcns_operations; - refcount_set(&ns->count, 1); + refcount_set(&ns->ns.count, 1); ns->user_ns = get_user_ns(user_ns); ns->ucounts = ucounts; @@ -164,7 +164,7 @@ static DECLARE_WORK(free_ipc_work, free_ipc); */ void put_ipc_ns(struct ipc_namespace *ns) { - if (refcount_dec_and_lock(&ns->count, &mq_lock)) { + if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) { mq_clear_sbinfo(ns); spin_unlock(&mq_lock);