sock: allow reading and changing sk_userlocks with setsockopt

SOCK_SNDBUF_LOCK and SOCK_RCVBUF_LOCK flags disable automatic socket
buffers adjustment done by kernel (see tcp_fixup_rcvbuf() and
tcp_sndbuf_expand()). If we've just created a new socket this adjustment
is enabled on it, but if one changes the socket buffer size by
setsockopt(SO_{SND,RCV}BUF*) it becomes disabled.

CRIU needs to call setsockopt(SO_{SND,RCV}BUF*) on each socket on
restore as it first needs to increase buffer sizes for packet queues
restore and second it needs to restore back original buffer sizes. So
after CRIU restore all sockets become non-auto-adjustable, which can
decrease network performance of restored applications significantly.

CRIU need to be able to restore sockets with enabled/disabled adjustment
to the same state it was before dump, so let's add special setsockopt
for it.

Let's also export SOCK_SNDBUF_LOCK and SOCK_RCVBUF_LOCK flags to uAPI so
that using these interface one can reenable automatic socket buffer
adjustment on their sockets.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index 6b3daba..1dd9baf 100644 (file)
--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h
@@ -129,6 +129,8 @@
 
 #define SO_NETNS_COOKIE                71
 
+#define SO_BUF_LOCK            72
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64

diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index cdf404a..1eaf6a1 100644 (file)
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -140,6 +140,8 @@
 
 #define SO_NETNS_COOKIE                71
 
+#define SO_BUF_LOCK            72
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64

diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
index 5b5351c..8baaad5 100644 (file)
--- a/arch/parisc/include/uapi/asm/socket.h
+++ b/arch/parisc/include/uapi/asm/socket.h
@@ -121,6 +121,8 @@
 
 #define SO_NETNS_COOKIE                0x4045
 
+#define SO_BUF_LOCK            0x4046
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64

diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index 92675dc..e80ee86 100644 (file)
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -122,6 +122,8 @@
 
 #define SO_NETNS_COOKIE          0x0050
 
+#define SO_BUF_LOCK              0x0051
+
 #if !defined(__KERNEL__)
 
 

diff --git a/include/net/sock.h b/include/net/sock.h
index ff1be7e..6e76145 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -68,6 +68,7 @@
 #include <net/tcp_states.h>
 #include <linux/net_tstamp.h>
 #include <net/l3mdev.h>
+#include <uapi/linux/socket.h>
 
 /*
  * This structure really needs to be cleaned up.
@@ -1438,8 +1439,6 @@ static inline int __sk_prot_rehash(struct sock *sk)
 #define RCV_SHUTDOWN   1
 #define SEND_SHUTDOWN  2
 
-#define SOCK_SNDBUF_LOCK       1
-#define SOCK_RCVBUF_LOCK       2
 #define SOCK_BINDADDR_LOCK     4
 #define SOCK_BINDPORT_LOCK     8
 

diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index d588c24..1f0a2b4 100644 (file)
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -124,6 +124,8 @@
 
 #define SO_NETNS_COOKIE                71
 
+#define SO_BUF_LOCK            72
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))

diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
index c3409c8..eb0a9a5 100644 (file)
--- a/include/uapi/linux/socket.h
+++ b/include/uapi/linux/socket.h
@@ -26,4 +26,9 @@ struct __kernel_sockaddr_storage {
        };
 };
 
+#define SOCK_SNDBUF_LOCK       1
+#define SOCK_RCVBUF_LOCK       2
+
+#define SOCK_BUF_LOCK_MASK (SOCK_SNDBUF_LOCK | SOCK_RCVBUF_LOCK)
+
 #endif /* _UAPI_LINUX_SOCKET_H */

diff --git a/net/core/sock.c b/net/core/sock.c
index 9671c32..aada649 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1358,6 +1358,15 @@ set_sndbuf:
                ret = sock_bindtoindex_locked(sk, val);
                break;
 
+       case SO_BUF_LOCK:
+               if (val & ~SOCK_BUF_LOCK_MASK) {
+                       ret = -EINVAL;
+                       break;
+               }
+               sk->sk_userlocks = val | (sk->sk_userlocks &
+                                         ~SOCK_BUF_LOCK_MASK);
+               break;
+
        default:
                ret = -ENOPROTOOPT;
                break;
@@ -1720,6 +1729,10 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
                v.val64 = sock_net(sk)->net_cookie;
                break;
 
+       case SO_BUF_LOCK:
+               v.val = sk->sk_userlocks & SOCK_BUF_LOCK_MASK;
+               break;
+
        default:
                /* We implement the SO_SNDLOWAT etc to not be settable
                 * (1003.1g 7).