From e11d4284e2f4de5048c6d1787c82226f0a198292 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 18 Apr 2018 13:43:52 +0200 Subject: 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 --- net/compat.c | 34 ++++++++++++---------------------- 1 file changed, 12 insertions(+), 22 deletions(-) (limited to 'net/compat.c') diff --git a/net/compat.c b/net/compat.c index 47a614b370cd..f7084780a8f8 100644 --- a/net/compat.c +++ b/net/compat.c @@ -810,34 +810,23 @@ COMPAT_SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, buf, compat_size_t, len return __compat_sys_recvfrom(fd, buf, len, flags, addr, addrlen); } -static int __compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg, - unsigned int vlen, unsigned int flags, - struct old_timespec32 __user *timeout) +COMPAT_SYSCALL_DEFINE5(recvmmsg_time64, int, fd, struct compat_mmsghdr __user *, mmsg, + unsigned int, vlen, unsigned int, flags, + struct __kernel_timespec __user *, timeout) { - int datagrams; - struct timespec64 ktspec; - - if (timeout == NULL) - return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen, - flags | MSG_CMSG_COMPAT, NULL); - - if (compat_get_timespec64(&ktspec, timeout)) - return -EFAULT; - - datagrams = __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen, - flags | MSG_CMSG_COMPAT, &ktspec); - if (datagrams > 0 && compat_put_timespec64(&ktspec, timeout)) - datagrams = -EFAULT; - - return datagrams; + return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen, + flags | MSG_CMSG_COMPAT, timeout, NULL); } +#ifdef CONFIG_COMPAT_32BIT_TIME COMPAT_SYSCALL_DEFINE5(recvmmsg, int, fd, struct compat_mmsghdr __user *, mmsg, unsigned int, vlen, unsigned int, flags, struct old_timespec32 __user *, timeout) { - return __compat_sys_recvmmsg(fd, mmsg, vlen, flags, timeout); + return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen, + flags | MSG_CMSG_COMPAT, NULL, timeout); } +#endif COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args) { @@ -925,8 +914,9 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args) ret = __compat_sys_recvmsg(a0, compat_ptr(a1), a[2]); break; case SYS_RECVMMSG: - ret = __compat_sys_recvmmsg(a0, compat_ptr(a1), a[2], a[3], - compat_ptr(a[4])); + ret = __sys_recvmmsg(a0, compat_ptr(a1), a[2], + a[3] | MSG_CMSG_COMPAT, NULL, + compat_ptr(a[4])); break; case SYS_ACCEPT4: ret = __sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]); -- cgit v1.2.3