Merge tag 'fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull misc fixes from Christian Brauner:
 "This contains several fixes which felt worth being combined into a
  single branch:

   - Use put_nsproxy() instead of open-coding it switch_task_namespaces()

   - Kirill's work to unify lifecycle management for all namespaces. The
     lifetime counters are used identically for all namespaces types.
     Namespaces may of course have additional unrelated counters and
     these are not altered. This work allows us to unify the type of the
     counters and reduces maintenance cost by moving the counter in one
     place and indicating that basic lifetime management is identical
     for all namespaces.

   - Peilin's fix adding three byte padding to Dmitry's
     PTRACE_GET_SYSCALL_INFO uapi struct to prevent an info leak.

   - Two smal patches to convert from the /* fall through */ comment
     annotation to the fallthrough keyword annotation which I had taken
     into my branch and into -next before df561f6688fe ("treewide: Use
     fallthrough pseudo-keyword") made it upstream which fixed this
     tree-wide.

     Since I didn't want to invalidate all testing for other commits I
     didn't rebase and kept them"

* tag 'fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  nsproxy: use put_nsproxy() in switch_task_namespaces()
  sys: Convert to the new fallthrough notation
  signal: Convert to the new fallthrough notation
  time: Use generic ns_common::count
  cgroup: Use generic ns_common::count
  mnt: Use generic ns_common::count
  user: Use generic ns_common::count
  pid: Use generic ns_common::count
  ipc: Use generic ns_common::count
  uts: Use generic ns_common::count
  net: Use generic ns_common::count
  ns: Add a common refcount into ns_common
  ptrace: Prevent kernel-infoleak in ptrace_get_syscall_info()

7 files changed, 17 insertions, 21 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 618838c48313..451c2d26a5db 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -854,7 +854,6 @@ static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
 #endif	/* CONFIG_CGROUP_DATA */
 
 struct cgroup_namespace {
-	refcount_t		count;
 	struct ns_common	ns;
 	struct user_namespace	*user_ns;
 	struct ucounts		*ucounts;
@@ -889,12 +888,12 @@ copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
 static inline void get_cgroup_ns(struct cgroup_namespace *ns)
 {
 	if (ns)
-		refcount_inc(&ns->count);
+		refcount_inc(&ns->ns.count);
 }
 
 static inline void put_cgroup_ns(struct cgroup_namespace *ns)
 {
-	if (ns && refcount_dec_and_test(&ns->count))
+	if (ns && refcount_dec_and_test(&ns->ns.count))
 		free_cgroup_ns(ns);
 }
 
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/include/linux/ns_common.h b/include/linux/ns_common.h
index 5fbc4000358f..0f1d024bd958 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h
@@ -2,12 +2,15 @@
 #ifndef _LINUX_NS_COMMON_H
 #define _LINUX_NS_COMMON_H
 
+#include <linux/refcount.h>
+
 struct proc_ns_operations;
 
 struct ns_common {
 	atomic_long_t stashed;
 	const struct proc_ns_operations *ops;
 	unsigned int inum;
+	refcount_t count;
 };
 
 #endif
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 5a5cb45ac57e..7c7e627503d2 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -8,7 +8,6 @@
 #include <linux/workqueue.h>
 #include <linux/threads.h>
 #include <linux/nsproxy.h>
-#include <linux/kref.h>
 #include <linux/ns_common.h>
 #include <linux/idr.h>
 
@@ -18,7 +17,6 @@
 struct fs_pin;
 
 struct pid_namespace {
-	struct kref kref;
 	struct idr idr;
 	struct rcu_head rcu;
 	unsigned int pid_allocated;
@@ -43,7 +41,7 @@ extern struct pid_namespace init_pid_ns;
 static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
 {
 	if (ns != &init_pid_ns)
-		kref_get(&ns->kref);
+		refcount_inc(&ns->ns.count);
 	return ns;
 }
 
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 30312166e70a..3146f1c056c9 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -4,7 +4,6 @@
 
 
 #include <linux/sched.h>
-#include <linux/kref.h>
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
@@ -18,7 +17,6 @@ struct timens_offsets {
 };
 
 struct time_namespace {
-	struct kref		kref;
 	struct user_namespace	*user_ns;
 	struct ucounts		*ucounts;
 	struct ns_common	ns;
@@ -37,20 +35,21 @@ extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
 
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
-	kref_get(&ns->kref);
+	refcount_inc(&ns->ns.count);
 	return ns;
 }
 
 struct time_namespace *copy_time_ns(unsigned long flags,
 				    struct user_namespace *user_ns,
 				    struct time_namespace *old_ns);
-void free_time_ns(struct kref *kref);
+void free_time_ns(struct time_namespace *ns);
 void timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
 struct vdso_data *arch_get_vdso_data(void *vvar_page);
 
 static inline void put_time_ns(struct time_namespace *ns)
 {
-	kref_put(&ns->kref, free_time_ns);
+	if (refcount_dec_and_test(&ns->ns.count))
+		free_time_ns(ns);
 }
 
 void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 6ef1c7109fc4..64cf8ebdc4ec 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -57,7 +57,6 @@ struct user_namespace {
 	struct uid_gid_map	uid_map;
 	struct uid_gid_map	gid_map;
 	struct uid_gid_map	projid_map;
-	atomic_t		count;
 	struct user_namespace	*parent;
 	int			level;
 	kuid_t			owner;
@@ -109,7 +108,7 @@ void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 {
 	if (ns)
-		atomic_inc(&ns->count);
+		refcount_inc(&ns->ns.count);
 	return ns;
 }
 
@@ -119,7 +118,7 @@ extern void __put_user_ns(struct user_namespace *ns);
 
 static inline void put_user_ns(struct user_namespace *ns)
 {
-	if (ns && atomic_dec_and_test(&ns->count))
+	if (ns && refcount_dec_and_test(&ns->ns.count))
 		__put_user_ns(ns);
 }
 
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 44429d9142ca..2b1737c9b244 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -4,7 +4,6 @@
 
 
 #include <linux/sched.h>
-#include <linux/kref.h>
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
@@ -22,7 +21,6 @@ struct user_namespace;
 extern struct user_namespace init_user_ns;
 
 struct uts_namespace {
-	struct kref kref;
 	struct new_utsname name;
 	struct user_namespace *user_ns;
 	struct ucounts *ucounts;
@@ -33,16 +31,17 @@ extern struct uts_namespace init_uts_ns;
 #ifdef CONFIG_UTS_NS
 static inline void get_uts_ns(struct uts_namespace *ns)
 {
-	kref_get(&ns->kref);
+	refcount_inc(&ns->ns.count);
 }
 
 extern struct uts_namespace *copy_utsname(unsigned long flags,
 	struct user_namespace *user_ns, struct uts_namespace *old_ns);
-extern void free_uts_ns(struct kref *kref);
+extern void free_uts_ns(struct uts_namespace *ns);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
 {
-	kref_put(&ns->kref, free_uts_ns);
+	if (refcount_dec_and_test(&ns->ns.count))
+		free_uts_ns(ns);
 }
 
 void uts_ns_init(void);