linux-kernel - [PATCH 4/6] epoll: deduplicate compat logic

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Date:   Mon, 11 Jan 2021 19:30:15 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
        akpm@...ux-foundation.org, willy@...radead.org, arnd@...nel.org,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH 4/6] epoll: deduplicate compat logic

From: Willem de Bruijn <willemb@...gle.com>

Apply the same compat deduplication strategy to epoll that was
previously applied to (p)select and ppoll.

Make do_epoll_wait handle both variants of sigmask. This removes
the need for near duplicate do_compat_epoll_pwait.

Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 fs/eventpoll.c | 38 +++++++++-----------------------------
 1 file changed, 9 insertions(+), 29 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index a829af074eb5..c9dcffba2da1 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2239,7 +2239,7 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
  */
 static int do_epoll_pwait(int epfd, struct epoll_event __user *events,
 			  int maxevents, struct timespec64 *to,
-			  const sigset_t __user *sigmask, size_t sigsetsize)
+			  const void __user *sigmask, size_t sigsetsize)
 {
 	int error;
 
@@ -2247,7 +2247,10 @@ static int do_epoll_pwait(int epfd, struct epoll_event __user *events,
 	 * If the caller wants a certain signal mask to be set during the wait,
 	 * we apply it here.
 	 */
-	error = set_user_sigmask(sigmask, sigsetsize);
+	if (!in_compat_syscall())
+		error = set_user_sigmask(sigmask, sigsetsize);
+	else
+		error = set_compat_user_sigmask(sigmask, sigsetsize);
 	if (error)
 		return error;
 
@@ -2288,28 +2291,6 @@ SYSCALL_DEFINE6(epoll_pwait2, int, epfd, struct epoll_event __user *, events,
 }
 
 #ifdef CONFIG_COMPAT
-static int do_compat_epoll_pwait(int epfd, struct epoll_event __user *events,
-				 int maxevents, struct timespec64 *timeout,
-				 const compat_sigset_t __user *sigmask,
-				 compat_size_t sigsetsize)
-{
-	long err;
-
-	/*
-	 * If the caller wants a certain signal mask to be set during the wait,
-	 * we apply it here.
-	 */
-	err = set_compat_user_sigmask(sigmask, sigsetsize);
-	if (err)
-		return err;
-
-	err = do_epoll_wait(epfd, events, maxevents, timeout);
-
-	restore_saved_sigmask_unless(err == -EINTR);
-
-	return err;
-}
-
 COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 		       struct epoll_event __user *, events,
 		       int, maxevents, int, timeout,
@@ -2318,9 +2299,9 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 {
 	struct timespec64 to;
 
-	return do_compat_epoll_pwait(epfd, events, maxevents,
-				     ep_timeout_to_timespec(&to, timeout),
-				     sigmask, sigsetsize);
+	return do_epoll_pwait(epfd, events, maxevents,
+			      ep_timeout_to_timespec(&to, timeout),
+			      sigmask, sigsetsize);
 }
 
 COMPAT_SYSCALL_DEFINE6(epoll_pwait2, int, epfd,
@@ -2340,8 +2321,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait2, int, epfd,
 			return -EINVAL;
 	}
 
-	return do_compat_epoll_pwait(epfd, events, maxevents, to,
-				     sigmask, sigsetsize);
+	return do_epoll_pwait(epfd, events, maxevents, to, sigmask, sigsetsize);
 }
 
 #endif
-- 
2.30.0.284.gd98b1dd5eaa7-goog