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Commit e11d4284 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

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: default avatarArnd Bergmann <arnd@arndb.de>
parent bec2f7cb

include/linux/compat.h

+3 −0
Original line number Diff line number Diff line
@@ -893,6 +893,9 @@ asmlinkage long compat_sys_move_pages(pid_t pid, compat_ulong_t nr_pages, 
asmlinkage long compat_sys_rt_tgsigqueueinfo(compat_pid_t tgid,

					compat_pid_t pid, int sig,

					struct compat_siginfo __user *uinfo);

asmlinkage long compat_sys_recvmmsg_time64(int fd, struct compat_mmsghdr __user *mmsg,

				    unsigned vlen, unsigned int flags,

				    struct __kernel_timespec __user *timeout);

asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,

				    unsigned vlen, unsigned int flags,

				    struct old_timespec32 __user *timeout);

include/linux/socket.h

+6 −3
Original line number Diff line number Diff line
@@ -348,7 +348,8 @@ struct ucred { 
extern int move_addr_to_kernel(void __user *uaddr, int ulen, struct sockaddr_storage *kaddr);

extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);



struct timespec64;

struct __kernel_timespec;

struct old_timespec32;



/* The __sys_...msg variants allow MSG_CMSG_COMPAT iff

 * forbid_cmsg_compat==false
@@ -357,8 +358,10 @@ extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, 
			  unsigned int flags, bool forbid_cmsg_compat);

extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg,

			  unsigned int flags, bool forbid_cmsg_compat);

extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,

			  unsigned int flags, struct timespec64 *timeout);

extern 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);

extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,

			  unsigned int vlen, unsigned int flags,

			  bool forbid_cmsg_compat);

include/linux/syscalls.h

+3 −0
Original line number Diff line number Diff line
@@ -843,6 +843,9 @@ asmlinkage long sys_accept4(int, struct sockaddr __user *, int __user *, int); 
asmlinkage long sys_recvmmsg(int fd, struct mmsghdr __user *msg,

			     unsigned int vlen, unsigned flags,

			     struct __kernel_timespec __user *timeout);

asmlinkage long sys_recvmmsg_time32(int fd, struct mmsghdr __user *msg,

			     unsigned int vlen, unsigned flags,

			     struct old_timespec32 __user *timeout);



asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,

				int options, struct rusage __user *ru);

kernel/sys_ni.c

+2 −0
Original line number Diff line number Diff line
@@ -284,7 +284,9 @@ COND_SYSCALL_COMPAT(move_pages); 
COND_SYSCALL(perf_event_open);

COND_SYSCALL(accept4);

COND_SYSCALL(recvmmsg);

COND_SYSCALL(recvmmsg_time32);

COND_SYSCALL_COMPAT(recvmmsg);

COND_SYSCALL_COMPAT(recvmmsg_time64);



/*

 * Architecture specific syscalls: see further below

net/compat.c

+12 −22
Original line number Diff line number Diff line
@@ -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;

			      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)

{
@@ -925,7 +914,8 @@ 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],

		ret = __sys_recvmmsg(a0, compat_ptr(a1), a[2],

				     a[3] | MSG_CMSG_COMPAT, NULL,

				     compat_ptr(a[4]));

		break;

	case SYS_ACCEPT4: