[PATCH net-next v6 05/11] seccomp: Split put_seccomp_filter() with put_seccomp()

[Mickaël Salaün]

The semantic is unchanged. This will be useful for the Landlock
integration with seccomp (next commit).

Signed-off-by: Mickaël Salaün <m...@digikod.net>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Will Drewry <w...@chromium.org>
---
 include/linux/seccomp.h |  4 ++--
 kernel/fork.c           |  2 +-
 kernel/seccomp.c        | 18 +++++++++++++-----
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index ecc296c137cd..e25aee2cdfc0 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -77,10 +77,10 @@ static inline int seccomp_mode(struct seccomp *s)
 #endif /* CONFIG_SECCOMP */
 
 #ifdef CONFIG_SECCOMP_FILTER
-extern void put_seccomp_filter(struct task_struct *tsk);
+extern void put_seccomp(struct task_struct *tsk);
 extern void get_seccomp_filter(struct task_struct *tsk);
 #else  /* CONFIG_SECCOMP_FILTER */
-static inline void put_seccomp_filter(struct task_struct *tsk)
+static inline void put_seccomp(struct task_struct *tsk)
 {
        return;
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 6c463c80e93d..a27d8e67ce33 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -363,7 +363,7 @@ void free_task(struct task_struct *tsk)
 #endif
        rt_mutex_debug_task_free(tsk);
        ftrace_graph_exit_task(tsk);
-       put_seccomp_filter(tsk);
+       put_seccomp(tsk);
        arch_release_task_struct(tsk);
        if (tsk->flags & PF_KTHREAD)
                free_kthread_struct(tsk);
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 65f61077ad50..326f79e32127 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -64,6 +64,8 @@ struct seccomp_filter {
 /* Limit any path through the tree to 256KB worth of instructions. */
 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
 
+static void put_seccomp_filter(struct seccomp_filter *filter);
+
 /*
  * Endianness is explicitly ignored and left for BPF program authors to manage
  * as per the specific architecture.
@@ -314,7 +316,7 @@ static inline void seccomp_sync_threads(void)
                 * current's path will hold a reference.  (This also
                 * allows a put before the assignment.)
                 */
-               put_seccomp_filter(thread);
+               put_seccomp_filter(thread->seccomp.filter);
                smp_store_release(&thread->seccomp.filter,
                                  caller->seccomp.filter);
 
@@ -476,10 +478,11 @@ static inline void seccomp_filter_free(struct 
seccomp_filter *filter)
        }
 }
 
-/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
-void put_seccomp_filter(struct task_struct *tsk)
+/* put_seccomp_filter - decrements the ref count of a filter */
+static void put_seccomp_filter(struct seccomp_filter *filter)
 {
-       struct seccomp_filter *orig = tsk->seccomp.filter;
+       struct seccomp_filter *orig = filter;
+
        /* Clean up single-reference branches iteratively. */
        while (orig && atomic_dec_and_test(&orig->usage)) {
                struct seccomp_filter *freeme = orig;
@@ -488,6 +491,11 @@ void put_seccomp_filter(struct task_struct *tsk)
        }
 }
 
+void put_seccomp(struct task_struct *tsk)
+{
+       put_seccomp_filter(tsk->seccomp.filter);
+}
+
 static void seccomp_init_siginfo(siginfo_t *info, int syscall, int reason)
 {
        memset(info, 0, sizeof(*info));
@@ -914,7 +922,7 @@ long seccomp_get_filter(struct task_struct *task, unsigned 
long filter_off,
        if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
                ret = -EFAULT;
 
-       put_seccomp_filter(task);
+       put_seccomp_filter(task->seccomp.filter);
        return ret;
 
 out:
-- 
2.11.0