y2038: socket: Add compat_sys_recvmmsg_time64
recvmmsg() takes two arguments to pointers of structures that differ
between 32-bit and 64-bit architectures: mmsghdr and timespec.
For y2038 compatbility, we are changing the native system call from
timespec to __kernel_timespec with a 64-bit time_t (in another patch),
and use the existing compat system call on both 32-bit and 64-bit
architectures for compatibility with traditional 32-bit user space.
As we now have two variants of recvmmsg() for 32-bit tasks that are both
different from the variant that we use on 64-bit tasks, this means we
also require two compat system calls!
The solution I picked is to flip things around: The existing
compat_sys_recvmmsg() call gets moved from net/compat.c into net/socket.c
and now handles the case for old user space on all architectures that
have set CONFIG_COMPAT_32BIT_TIME. A new compat_sys_recvmmsg_time64()
call gets added in the old place for 64-bit architectures only, this
one handles the case of a compat mmsghdr structure combined with
__kernel_timespec.
In the indirect sys_socketcall(), we now need to call either
do_sys_recvmmsg() or __compat_sys_recvmmsg(), depending on what kind of
architecture we are on. For compat_sys_socketcall(), no such change is
needed, we always call __compat_sys_recvmmsg().
I decided to not add a new SYS_RECVMMSG_TIME64 socketcall: Any libc
implementation for 64-bit time_t will need significant changes including
an updated asm/unistd.h, and it seems better to consistently use the
separate syscalls that configuration, leaving the socketcall only for
backward compatibility with 32-bit time_t based libc.
The naming is asymmetric for the moment, so both existing syscalls
entry points keep their names, while the new ones are recvmmsg_time32
and compat_recvmmsg_time64 respectively. I expect that we will rename
the compat syscalls later as we start using generated syscall tables
everywhere and add these entry points.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/net/socket.c b/net/socket.c
index 593826e..f137a96 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2341,8 +2341,9 @@ SYSCALL_DEFINE3(recvmsg, int, fd, struct user_msghdr __user *, msg,
* Linux recvmmsg interface
*/
-int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
- unsigned int flags, struct timespec64 *timeout)
+static int do_recvmmsg(int fd, struct mmsghdr __user *mmsg,
+ unsigned int vlen, unsigned int flags,
+ struct timespec64 *timeout)
{
int fput_needed, err, datagrams;
struct socket *sock;
@@ -2451,25 +2452,32 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
return datagrams;
}
-static int do_sys_recvmmsg(int fd, struct mmsghdr __user *mmsg,
- unsigned int vlen, unsigned int flags,
- struct __kernel_timespec __user *timeout)
+int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg,
+ unsigned int vlen, unsigned int flags,
+ struct __kernel_timespec __user *timeout,
+ struct old_timespec32 __user *timeout32)
{
int datagrams;
struct timespec64 timeout_sys;
- if (flags & MSG_CMSG_COMPAT)
- return -EINVAL;
-
- if (!timeout)
- return __sys_recvmmsg(fd, mmsg, vlen, flags, NULL);
-
- if (get_timespec64(&timeout_sys, timeout))
+ if (timeout && get_timespec64(&timeout_sys, timeout))
return -EFAULT;
- datagrams = __sys_recvmmsg(fd, mmsg, vlen, flags, &timeout_sys);
+ if (timeout32 && get_old_timespec32(&timeout_sys, timeout32))
+ return -EFAULT;
- if (datagrams > 0 && put_timespec64(&timeout_sys, timeout))
+ if (!timeout && !timeout32)
+ return do_recvmmsg(fd, mmsg, vlen, flags, NULL);
+
+ datagrams = do_recvmmsg(fd, mmsg, vlen, flags, &timeout_sys);
+
+ if (datagrams <= 0)
+ return datagrams;
+
+ if (timeout && put_timespec64(&timeout_sys, timeout))
+ datagrams = -EFAULT;
+
+ if (timeout32 && put_old_timespec32(&timeout_sys, timeout32))
datagrams = -EFAULT;
return datagrams;
@@ -2479,9 +2487,24 @@ SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg,
unsigned int, vlen, unsigned int, flags,
struct __kernel_timespec __user *, timeout)
{
- return do_sys_recvmmsg(fd, mmsg, vlen, flags, timeout);
+ if (flags & MSG_CMSG_COMPAT)
+ return -EINVAL;
+
+ return __sys_recvmmsg(fd, mmsg, vlen, flags, timeout, NULL);
}
+#ifdef CONFIG_COMPAT_32BIT_TIME
+SYSCALL_DEFINE5(recvmmsg_time32, int, fd, struct mmsghdr __user *, mmsg,
+ unsigned int, vlen, unsigned int, flags,
+ struct old_timespec32 __user *, timeout)
+{
+ if (flags & MSG_CMSG_COMPAT)
+ return -EINVAL;
+
+ return __sys_recvmmsg(fd, mmsg, vlen, flags, NULL, timeout);
+}
+#endif
+
#ifdef __ARCH_WANT_SYS_SOCKETCALL
/* Argument list sizes for sys_socketcall */
#define AL(x) ((x) * sizeof(unsigned long))
@@ -2600,8 +2623,15 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
a[2], true);
break;
case SYS_RECVMMSG:
- err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2],
- a[3], (struct __kernel_timespec __user *)a[4]);
+ if (IS_ENABLED(CONFIG_64BIT) || !IS_ENABLED(CONFIG_64BIT_TIME))
+ err = __sys_recvmmsg(a0, (struct mmsghdr __user *)a1,
+ a[2], a[3],
+ (struct __kernel_timespec __user *)a[4],
+ NULL);
+ else
+ err = __sys_recvmmsg(a0, (struct mmsghdr __user *)a1,
+ a[2], a[3], NULL,
+ (struct old_timespec32 __user *)a[4]);
break;
case SYS_ACCEPT4:
err = __sys_accept4(a0, (struct sockaddr __user *)a1,
