net: socket: implement 64-bit timestamps

The 'timeval' and 'timespec' data structures used for socket timestamps
are going to be redefined in user space based on 64-bit time_t in future
versions of the C library to deal with the y2038 overflow problem,
which breaks the ABI definition.

Unlike many modern ioctl commands, SIOCGSTAMP and SIOCGSTAMPNS do not
use the _IOR() macro to encode the size of the transferred data, so it
remains ambiguous whether the application uses the old or new layout.

The best workaround I could find is rather ugly: we redefine the command
code based on the size of the respective data structure with a ternary
operator. This lets it get evaluated as late as possible, hopefully after
that structure is visible to the caller. We cannot use an #ifdef here,
because inux/sockios.h might have been included before any libc header
that could determine the size of time_t.

The ioctl implementation now interprets the new command codes as always
referring to the 64-bit structure on all architectures, while the old
architecture specific command code still refers to the old architecture
specific layout. The new command number is only used when they are
actually different.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 6 deletions

diff --git a/net/socket.c b/net/socket.c
index ab624d42ead5..8d9d4fc7d962 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1164,14 +1164,24 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 
                         err = open_related_ns(&net->ns, get_net_ns);
                         break;
-                case SIOCGSTAMP:
-                case SIOCGSTAMPNS:
+                case SIOCGSTAMP_OLD:
+                case SIOCGSTAMPNS_OLD:
                         if (!sock->ops->gettstamp) {
                                 err = -ENOIOCTLCMD;
                                 break;
                         }
                         err = sock->ops->gettstamp(sock, argp,
-                                                   cmd == SIOCGSTAMP, false);
+                                                   cmd == SIOCGSTAMP_OLD,
+                                                   !IS_ENABLED(CONFIG_64BIT));
+                case SIOCGSTAMP_NEW:
+                case SIOCGSTAMPNS_NEW:
+                        if (!sock->ops->gettstamp) {
+                                err = -ENOIOCTLCMD;
+                                break;
+                        }
+                        err = sock->ops->gettstamp(sock, argp,
+                                                   cmd == SIOCGSTAMP_NEW,
+                                                   false);
                         break;
                 default:
                         err = sock_do_ioctl(net, sock, cmd, arg);
@@ -3324,11 +3334,11 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
         case SIOCADDRT:
         case SIOCDELRT:
                 return routing_ioctl(net, sock, cmd, argp);
-        case SIOCGSTAMP:
-        case SIOCGSTAMPNS:
+        case SIOCGSTAMP_OLD:
+        case SIOCGSTAMPNS_OLD:
                 if (!sock->ops->gettstamp)
                         return -ENOIOCTLCMD;
-                return sock->ops->gettstamp(sock, argp, cmd == SIOCGSTAMP,
+                return sock->ops->gettstamp(sock, argp, cmd == SIOCGSTAMP_OLD,
                                             !COMPAT_USE_64BIT_TIME);
 
         case SIOCBONDSLAVEINFOQUERY:
@@ -3348,6 +3358,8 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
         case SIOCADDDLCI:
         case SIOCDELDLCI:
         case SIOCGSKNS:
+        case SIOCGSTAMP_NEW:
+        case SIOCGSTAMPNS_NEW:
                 return sock_ioctl(file, cmd, arg);
 
         case SIOCGIFFLAGS: