path: root/net/compat.c
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authorArnd Bergmann <arnd@arndb.de>2018-04-18 13:43:52 +0200
committerArnd Bergmann <arnd@arndb.de>2018-12-18 16:13:04 +0100
commite11d4284e2f4de5048c6d1787c82226f0a198292 (patch)
treebc52de794fd0fc90e2842a9d680239d6c3e9c215 /net/compat.c
parentbec2f7cbb73eadf5e1cc7d54ecb0980ede244257 (diff)
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>
Diffstat (limited to 'net/compat.c')
1 files changed, 12 insertions, 22 deletions
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,
- 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);
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);
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]);
- 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],
+ compat_ptr(a[4]));
ret = __sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]);