net: implement a SO_DOMAIN getsockoption

This sockopt goes in line with SO_TYPE and SO_PROTOCOL. It makes it
possible for userspace programs to pass around file descriptors — I
am referring to arguments-to-functions, but it may even work for the
fd passing over UNIX sockets — without needing to also pass the
auxiliary information (PF_INET6/IPPROTO_TCP).

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

20 files changed, 24 insertions, 0 deletions

diff --git a/arch/alpha/include/asm/socket.h b/arch/alpha/include/asm/socket.h
index 2f8b4d377749..26773e3246e2 100644
--- a/arch/alpha/include/asm/socket.h
+++ b/arch/alpha/include/asm/socket.h
@@ -33,6 +33,7 @@
 #define	SO_SNDTIMEO	0x1013
 #define SO_ACCEPTCONN	0x1014
 #define SO_PROTOCOL	0x1028
+#define SO_DOMAIN	0x1029
 
 /* linux-specific, might as well be the same as on i386 */
 #define SO_NO_CHECK	11
diff --git a/arch/arm/include/asm/socket.h b/arch/arm/include/asm/socket.h
index 7f47454ffbf3..92ac61d294fd 100644
--- a/arch/arm/include/asm/socket.h
+++ b/arch/arm/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/avr32/include/asm/socket.h b/arch/avr32/include/asm/socket.h
index 6af2866a4f00..fe863f9794d5 100644
--- a/arch/avr32/include/asm/socket.h
+++ b/arch/avr32/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* __ASM_AVR32_SOCKET_H */
diff --git a/arch/cris/include/asm/socket.h b/arch/cris/include/asm/socket.h
index f3859fb0990c..45ec49bdb7b1 100644
--- a/arch/cris/include/asm/socket.h
+++ b/arch/cris/include/asm/socket.h
@@ -60,6 +60,7 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
 
diff --git a/arch/frv/include/asm/socket.h b/arch/frv/include/asm/socket.h
index 8dab3486ffa4..2dea726095c2 100644
--- a/arch/frv/include/asm/socket.h
+++ b/arch/frv/include/asm/socket.h
@@ -58,6 +58,7 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
 
diff --git a/arch/h8300/include/asm/socket.h b/arch/h8300/include/asm/socket.h
index ba770d09cd63..1547f01c8e22 100644
--- a/arch/h8300/include/asm/socket.h
+++ b/arch/h8300/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/ia64/include/asm/socket.h b/arch/ia64/include/asm/socket.h
index 091cd9d47d0f..0b0d5ff062e5 100644
--- a/arch/ia64/include/asm/socket.h
+++ b/arch/ia64/include/asm/socket.h
@@ -67,5 +67,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_IA64_SOCKET_H */
diff --git a/arch/m32r/include/asm/socket.h b/arch/m32r/include/asm/socket.h
index d36f5928fb79..3390a864f224 100644
--- a/arch/m32r/include/asm/socket.h
+++ b/arch/m32r/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_M32R_SOCKET_H */
diff --git a/arch/m68k/include/asm/socket.h b/arch/m68k/include/asm/socket.h
index 060cb7ed024f..eee01cce921b 100644
--- a/arch/m68k/include/asm/socket.h
+++ b/arch/m68k/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/microblaze/include/asm/socket.h b/arch/microblaze/include/asm/socket.h
index 96bf8bfa935e..7361ae7cfcde 100644
--- a/arch/microblaze/include/asm/socket.h
+++ b/arch/microblaze/include/asm/socket.h
@@ -67,5 +67,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_MICROBLAZE_SOCKET_H */
diff --git a/arch/mips/include/asm/socket.h b/arch/mips/include/asm/socket.h
index 289ce5f5f2a3..ae05accd9fe4 100644
--- a/arch/mips/include/asm/socket.h
+++ b/arch/mips/include/asm/socket.h
@@ -43,6 +43,7 @@ To add: #define SO_REUSEPORT 0x0200	/* Allow local address and port reuse.  */
 #define SO_RCVTIMEO 	0x1006	/* receive timeout */
 #define SO_ACCEPTCONN	0x1009
 #define SO_PROTOCOL	0x1028	/* protocol type */
+#define SO_DOMAIN	0x1029	/* domain/socket family */
 
 /* linux-specific, might as well be the same as on i386 */
 #define SO_NO_CHECK	11
diff --git a/arch/mn10300/include/asm/socket.h b/arch/mn10300/include/asm/socket.h
index 19d7cf709b77..4df75af29d76 100644
--- a/arch/mn10300/include/asm/socket.h
+++ b/arch/mn10300/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/parisc/include/asm/socket.h b/arch/parisc/include/asm/socket.h
index a658b09df624..960b1e5d8e16 100644
--- a/arch/parisc/include/asm/socket.h
+++ b/arch/parisc/include/asm/socket.h
@@ -25,6 +25,7 @@
 #define SO_ERROR	0x1007
 #define SO_TYPE		0x1008
 #define SO_PROTOCOL	0x1028
+#define SO_DOMAIN	0x1029
 #define SO_PEERNAME	0x2000
 
 #define SO_NO_CHECK	0x400b
diff --git a/arch/powerpc/include/asm/socket.h b/arch/powerpc/include/asm/socket.h
index 609049d7117e..3ab8b3e6feb0 100644
--- a/arch/powerpc/include/asm/socket.h
+++ b/arch/powerpc/include/asm/socket.h
@@ -65,5 +65,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif	/* _ASM_POWERPC_SOCKET_H */
diff --git a/arch/s390/include/asm/socket.h b/arch/s390/include/asm/socket.h
index 65baa9a83abc..e42df89a0b85 100644
--- a/arch/s390/include/asm/socket.h
+++ b/arch/s390/include/asm/socket.h
@@ -66,5 +66,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_SOCKET_H */
diff --git a/arch/sparc/include/asm/socket.h b/arch/sparc/include/asm/socket.h
index 9cbbfafd0538..3a5ae3d12088 100644
--- a/arch/sparc/include/asm/socket.h
+++ b/arch/sparc/include/asm/socket.h
@@ -30,6 +30,7 @@
 #define SO_ERROR	0x1007
 #define SO_TYPE		0x1008
 #define SO_PROTOCOL	0x1028
+#define SO_DOMAIN	0x1029
 
 
 /* Linux specific, keep the same. */
diff --git a/arch/x86/include/asm/socket.h b/arch/x86/include/asm/socket.h
index 1077d2535a32..b2a8c74f2d06 100644
--- a/arch/x86/include/asm/socket.h
+++ b/arch/x86/include/asm/socket.h
@@ -58,5 +58,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* _ASM_X86_SOCKET_H */
diff --git a/arch/xtensa/include/asm/socket.h b/arch/xtensa/include/asm/socket.h
index e47f172142f1..beb3a6bdb61d 100644
--- a/arch/xtensa/include/asm/socket.h
+++ b/arch/xtensa/include/asm/socket.h
@@ -69,5 +69,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif	/* _XTENSA_SOCKET_H */
diff --git a/include/asm-generic/socket.h b/include/asm-generic/socket.h
index 7e24d186616e..538991cef6f0 100644
--- a/include/asm-generic/socket.h
+++ b/include/asm-generic/socket.h
@@ -61,5 +61,6 @@
 #define SCM_TIMESTAMPING	SO_TIMESTAMPING
 
 #define SO_PROTOCOL		38
+#define SO_DOMAIN		39
 
 #endif /* __ASM_GENERIC_SOCKET_H */
diff --git a/net/core/sock.c b/net/core/sock.c
index ebce661234ac..3ac34ea6ec05 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -483,6 +483,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 		break;
 	case SO_TYPE:
 	case SO_PROTOCOL:
+	case SO_DOMAIN:
 	case SO_ERROR:
 		ret = -ENOPROTOOPT;
 		break;
@@ -769,6 +770,10 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 		v.val = sk->sk_protocol;
 		break;
 
+	case SO_DOMAIN:
+		v.val = sk->sk_family;
+		break;
+
 	case SO_ERROR:
 		v.val = -sock_error(sk);
 		if (v.val == 0)