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y2038: socket: Add compat_sys_recvmmsg_time64

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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>
This commit is contained in:
Arnd Bergmann 2018-04-18 13:43:52 +02:00
parent bec2f7cbb7
commit e11d4284e2
6 changed files with 73 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/compat.h
View File

@ -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);

9
include/linux/socket.h
View File

@ -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);

3
include/linux/syscalls.h
View File

@ -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);

2
kernel/sys_ni.c
View File

@ -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

34
net/compat.c
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@ -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]);

64
net/socket.c
View File

@ -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 @@ out_put:
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,