[RFC PATCH v3] parisc: Add wrapper syscalls to fix O_NONBLOCK flag usage

[Helge Deller <deller@gmx.de>]

The commit 75ae04206a4d ("parisc: Define O_NONBLOCK to become
000200000") changed the O_NONBLOCK constant to have only one bit set
(like all other architectures). This change broke some existing
userspace code (e.g.  udevadm, systemd-udevd, elogind) which called
specific syscalls which do strict value checking on their flag
parameter.

This patch adds wrapper functions for the relevant syscalls. The
wrappers masks out any old invalid O_NONBLOCK flags, reports in the
syslog if the old O_NONBLOCK value was used and then calls the target
syscall with the new O_NONBLOCK value.

Fixes: 75ae04206a4d ("parisc: Define O_NONBLOCK to become 000200000")
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: Meelis Roos <mroos@linux.ee>
Tested-by: Jeroen Roovers <jer@xs4all.nl>

--
v3: Added inotify_init1() syscall wrapper
    Changed warning to pr_warn_once()

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 5d458a44b09c..9549496f5523 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -6,7 +6,7 @@
  *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
  *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
  *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
- *    Copyright (C) 1999-2014 Helge Deller <deller@gmx.de>
+ *    Copyright (C) 1999-2020 Helge Deller <deller@gmx.de>
  */

 #include <linux/uaccess.h>
@@ -23,6 +23,7 @@
 #include <linux/utsname.h>
 #include <linux/personality.h>
 #include <linux/random.h>
+#include <linux/compat.h>

 /* we construct an artificial offset for the mapping based on the physical
  * address of the kernel mapping variable */
@@ -373,3 +374,73 @@ long parisc_personality(unsigned long personality)

 	return err;
 }
+
+/*
+ * Up to kernel v5.9 we defined O_NONBLOCK as 000200004,
+ * since then O_NONBLOCK is defined as 000200000.
+ *
+ * The following wrapper functions mask out the old
+ * O_NDELAY bit from calls which use O_NONBLOCK.
+ *
+ * XXX: Remove those in year 2022 (or later)?
+ */
+
+#define O_NONBLOCK_OLD		000200004
+#define O_NONBLOCK_MASK_OUT	(O_NONBLOCK_OLD & ~O_NONBLOCK)
+
+static int FIX_O_NONBLOCK(int flags)
+{
+	if (flags & O_NONBLOCK_MASK_OUT) {
+		struct task_struct *tsk = current;
+		pr_warn_once("%s(%d) uses a deprecated O_NONBLOCK value.\n",
+			tsk->comm, tsk->pid);
+	}
+	return flags & ~O_NONBLOCK_MASK_OUT;
+}
+
+asmlinkage long parisc_timerfd_create(int clockid, int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_timerfd_create(clockid, flags);
+}
+
+asmlinkage long parisc_signalfd4(int ufd, sigset_t __user *user_mask,
+	size_t sizemask, int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_signalfd4(ufd, user_mask, sizemask, flags);
+}
+
+#ifdef CONFIG_COMPAT
+asmlinkage long parisc_compat_signalfd4(int ufd,
+	compat_sigset_t __user *user_mask,
+	compat_size_t sizemask, int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return compat_sys_signalfd4(ufd, user_mask, sizemask, flags);
+}
+#endif
+
+asmlinkage long parisc_eventfd2(unsigned int count, int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_eventfd2(count, flags);
+}
+
+asmlinkage long parisc_userfaultfd(int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_userfaultfd(flags);
+}
+
+asmlinkage long parisc_pipe2(int __user *fildes, int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_pipe2(fildes, flags);
+}
+
+asmlinkage long parisc_inotify_init1(int flags)
+{
+	flags = FIX_O_NONBLOCK(flags);
+	return sys_inotify_init1(flags);
+}
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index 38c63e5404bc..f375ea528e59 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -344,17 +344,17 @@
 304	common	eventfd			sys_eventfd
 305	32	fallocate		parisc_fallocate
 305	64	fallocate		sys_fallocate
-306	common	timerfd_create		sys_timerfd_create
+306	common	timerfd_create		parisc_timerfd_create
 307	32	timerfd_settime		sys_timerfd_settime32
 307	64	timerfd_settime		sys_timerfd_settime
 308	32	timerfd_gettime		sys_timerfd_gettime32
 308	64	timerfd_gettime		sys_timerfd_gettime
-309	common	signalfd4		sys_signalfd4			compat_sys_signalfd4
-310	common	eventfd2		sys_eventfd2
+309	common	signalfd4		parisc_signalfd4		parisc_compat_signalfd4
+310	common	eventfd2		parisc_eventfd2
 311	common	epoll_create1		sys_epoll_create1
 312	common	dup3			sys_dup3
-313	common	pipe2			sys_pipe2
-314	common	inotify_init1		sys_inotify_init1
+313	common	pipe2			parisc_pipe2
+314	common	inotify_init1		parisc_inotify_init1
 315	common	preadv	sys_preadv	compat_sys_preadv
 316	common	pwritev	sys_pwritev	compat_sys_pwritev
 317	common	rt_tgsigqueueinfo	sys_rt_tgsigqueueinfo		compat_sys_rt_tgsigqueueinfo
@@ -387,7 +387,7 @@
 341	common	bpf			sys_bpf
 342	common	execveat		sys_execveat			compat_sys_execveat
 343	common	membarrier		sys_membarrier
-344	common	userfaultfd		sys_userfaultfd
+344	common	userfaultfd		parisc_userfaultfd
 345	common	mlock2			sys_mlock2
 346	common	copy_file_range		sys_copy_file_range
 347	common	preadv2			sys_preadv2			compat_sys_preadv2