4 files changed, 169 insertions, 20 deletions

diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 997f9f2f0963..e7c94eeb9475 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -227,6 +227,7 @@ header-y += kvm_para.h
 endif
 
 header-y += l2tp.h
+header-y += libc-compat.h
 header-y += limits.h
 header-y += llc.h
 header-y += loop.h
diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
index 9edb441df827..f9e8e496ae5d 100644
--- a/include/uapi/linux/in.h
+++ b/include/uapi/linux/in.h
@@ -24,30 +24,53 @@
 /* Standard well-defined IP protocols.  */
 enum {
   IPPROTO_IP = 0,               /* Dummy protocol for TCP               */
+#define IPPROTO_IP              IPPROTO_IP
   IPPROTO_ICMP = 1,             /* Internet Control Message Protocol    */
+#define IPPROTO_ICMP            IPPROTO_ICMP
   IPPROTO_IGMP = 2,             /* Internet Group Management Protocol   */
+#define IPPROTO_IGMP            IPPROTO_IGMP
   IPPROTO_IPIP = 4,             /* IPIP tunnels (older KA9Q tunnels use 94) */
+#define IPPROTO_IPIP            IPPROTO_IPIP
   IPPROTO_TCP = 6,              /* Transmission Control Protocol        */
+#define IPPROTO_TCP             IPPROTO_TCP
   IPPROTO_EGP = 8,              /* Exterior Gateway Protocol            */
+#define IPPROTO_EGP             IPPROTO_EGP
   IPPROTO_PUP = 12,             /* PUP protocol                         */
+#define IPPROTO_PUP             IPPROTO_PUP
   IPPROTO_UDP = 17,             /* User Datagram Protocol               */
+#define IPPROTO_UDP             IPPROTO_UDP
   IPPROTO_IDP = 22,             /* XNS IDP protocol                     */
+#define IPPROTO_IDP             IPPROTO_IDP
+  IPPROTO_TP = 29,              /* SO Transport Protocol Class 4        */
+#define IPPROTO_TP              IPPROTO_TP
   IPPROTO_DCCP = 33,            /* Datagram Congestion Control Protocol */
-  IPPROTO_RSVP = 46,            /* RSVP protocol                        */
+#define IPPROTO_DCCP            IPPROTO_DCCP
+  IPPROTO_IPV6 = 41,            /* IPv6-in-IPv4 tunnelling              */
+#define IPPROTO_IPV6            IPPROTO_IPV6
+  IPPROTO_RSVP = 46,            /* RSVP Protocol                        */
+#define IPPROTO_RSVP            IPPROTO_RSVP
   IPPROTO_GRE = 47,             /* Cisco GRE tunnels (rfc 1701,1702)    */
-
-  IPPROTO_IPV6   = 41,          /* IPv6-in-IPv4 tunnelling              */
-
-  IPPROTO_ESP = 50,            /* Encapsulation Security Payload protocol */
-  IPPROTO_AH = 51,             /* Authentication Header protocol       */
-  IPPROTO_BEETPH = 94,         /* IP option pseudo header for BEET */
-  IPPROTO_PIM    = 103,         /* Protocol Independent Multicast       */
-
-  IPPROTO_COMP   = 108,                /* Compression Header protocol */
-  IPPROTO_SCTP   = 132,         /* Stream Control Transport Protocol    */
+#define IPPROTO_GRE             IPPROTO_GRE
+  IPPROTO_ESP = 50,             /* Encapsulation Security Payload protocol */
+#define IPPROTO_ESP             IPPROTO_ESP
+  IPPROTO_AH = 51,              /* Authentication Header protocol       */
+#define IPPROTO_AH              IPPROTO_AH
+  IPPROTO_MTP = 92,             /* Multicast Transport Protocol         */
+#define IPPROTO_MTP             IPPROTO_MTP
+  IPPROTO_BEETPH = 94,          /* IP option pseudo header for BEET     */
+#define IPPROTO_BEETPH          IPPROTO_BEETPH
+  IPPROTO_ENCAP = 98,           /* Encapsulation Header                 */
+#define IPPROTO_ENCAP           IPPROTO_ENCAP
+  IPPROTO_PIM = 103,            /* Protocol Independent Multicast       */
+#define IPPROTO_PIM             IPPROTO_PIM
+  IPPROTO_COMP = 108,           /* Compression Header Protocol          */
+#define IPPROTO_COMP            IPPROTO_COMP
+  IPPROTO_SCTP = 132,           /* Stream Control Transport Protocol    */
+#define IPPROTO_SCTP            IPPROTO_SCTP
   IPPROTO_UDPLITE = 136,        /* UDP-Lite (RFC 3828)                  */
-
-  IPPROTO_RAW    = 255,         /* Raw IP packets                       */
+#define IPPROTO_UDPLITE         IPPROTO_UDPLITE
+  IPPROTO_RAW = 255,            /* Raw IP packets                       */
+#define IPPROTO_RAW             IPPROTO_RAW
   IPPROTO_MAX
 };
 
diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
index 53b1d56a6e7f..440d5c479145 100644
--- a/include/uapi/linux/in6.h
+++ b/include/uapi/linux/in6.h
@@ -22,22 +22,30 @@
 #define _UAPI_LINUX_IN6_H
 
 #include <linux/types.h>
+#include <linux/libc-compat.h>
 
 /*
  *      IPv6 address structure
  */
 
+#if __UAPI_DEF_IN6_ADDR
 struct in6_addr {
         union {
                 __u8            u6_addr8[16];
+#if __UAPI_DEF_IN6_ADDR_ALT
                 __be16          u6_addr16[8];
                 __be32          u6_addr32[4];
+#endif
         } in6_u;
 #define s6_addr                 in6_u.u6_addr8
+#if __UAPI_DEF_IN6_ADDR_ALT
 #define s6_addr16               in6_u.u6_addr16
 #define s6_addr32               in6_u.u6_addr32
+#endif
 };
+#endif /* __UAPI_DEF_IN6_ADDR */
 
+#if __UAPI_DEF_SOCKADDR_IN6
 struct sockaddr_in6 {
         unsigned short int      sin6_family;    /* AF_INET6 */
         __be16                  sin6_port;      /* Transport layer port # */
@@ -45,7 +53,9 @@ struct sockaddr_in6 {
         struct in6_addr         sin6_addr;      /* IPv6 address */
         __u32                   sin6_scope_id;  /* scope id (new in RFC2553) */
 };
+#endif /* __UAPI_DEF_SOCKADDR_IN6 */
 
+#if __UAPI_DEF_IPV6_MREQ
 struct ipv6_mreq {
         /* IPv6 multicast address of group */
         struct in6_addr ipv6mr_multiaddr;
@@ -53,6 +63,7 @@ struct ipv6_mreq {
         /* local IPv6 address of interface */
         int             ipv6mr_ifindex;
 };
+#endif /* __UAPI_DEF_IVP6_MREQ */
 
 #define ipv6mr_acaddr   ipv6mr_multiaddr
 
@@ -114,13 +125,24 @@ struct in6_flowlabel_req {
 /*
  *      IPV6 extension headers
  */
-#define IPPROTO_HOPOPTS         0       /* IPv6 hop-by-hop options      */
-#define IPPROTO_ROUTING         43      /* IPv6 routing header          */
-#define IPPROTO_FRAGMENT        44      /* IPv6 fragmentation header    */
-#define IPPROTO_ICMPV6          58      /* ICMPv6                       */
-#define IPPROTO_NONE            59      /* IPv6 no next header          */
-#define IPPROTO_DSTOPTS         60      /* IPv6 destination options     */
-#define IPPROTO_MH              135     /* IPv6 mobility header         */
+#if __UAPI_DEF_IPPROTO_V6
+enum {
+  IPPROTO_HOPOPTS = 0,          /* IPv6 hop-by-hop options      */
+#define IPPROTO_HOPOPTS         IPPROTO_HOPOPTS
+  IPPROTO_ROUTING = 43,         /* IPv6 routing header          */
+#define IPPROTO_ROUTING         IPPROTO_ROUTING
+  IPPROTO_FRAGMENT = 44,        /* IPv6 fragmentation header    */
+#define IPPROTO_FRAGMENT        IPPROTO_FRAGMENT
+  IPPROTO_ICMPV6 = 58,          /* ICMPv6                       */
+#define IPPROTO_ICMPV6          IPPROTO_ICMPV6
+  IPPROTO_NONE = 59,            /* IPv6 no next header          */
+#define IPPROTO_NONE            IPPROTO_NONE
+  IPPROTO_DSTOPTS = 60,         /* IPv6 destination options     */
+#define IPPROTO_DSTOPTS         IPPROTO_DSTOPTS
+  IPPROTO_MH = 135,             /* IPv6 mobility header         */
+#define IPPROTO_MH              IPPROTO_MH
+};
+#endif /* __UAPI_DEF_IPPROTO_V6 */
 
 /*
  *      IPv6 TLV options.
diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h
new file mode 100644
index 000000000000..335e8a7cad39
--- /dev/null
+++ b/include/uapi/linux/libc-compat.h
@@ -0,0 +1,103 @@
+/*
+ * Compatibility interface for userspace libc header coordination:
+ *
+ * Define compatibility macros that are used to control the inclusion or
+ * exclusion of UAPI structures and definitions in coordination with another
+ * userspace C library.
+ *
+ * This header is intended to solve the problem of UAPI definitions that
+ * conflict with userspace definitions. If a UAPI header has such conflicting
+ * definitions then the solution is as follows:
+ *
+ * * Synchronize the UAPI header and the libc headers so either one can be
+ *   used and such that the ABI is preserved. If this is not possible then
+ *   no simple compatibility interface exists (you need to write translating
+ *   wrappers and rename things) and you can't use this interface.
+ *
+ * Then follow this process:
+ *
+ * (a) Include libc-compat.h in the UAPI header.
+ *      e.g. #include <linux/libc-compat.h>
+ *     This include must be as early as possible.
+ *
+ * (b) In libc-compat.h add enough code to detect that the comflicting
+ *     userspace libc header has been included first.
+ *
+ * (c) If the userspace libc header has been included first define a set of
+ *     guard macros of the form __UAPI_DEF_FOO and set their values to 1, else
+ *     set their values to 0.
+ *
+ * (d) Back in the UAPI header with the conflicting definitions, guard the
+ *     definitions with:
+ *     #if __UAPI_DEF_FOO
+ *       ...
+ *     #endif
+ *
+ * This fixes the situation where the linux headers are included *after* the
+ * libc headers. To fix the problem with the inclusion in the other order the
+ * userspace libc headers must be fixed like this:
+ *
+ * * For all definitions that conflict with kernel definitions wrap those
+ *   defines in the following:
+ *   #if !__UAPI_DEF_FOO
+ *     ...
+ *   #endif
+ *
+ * This prevents the redefinition of a construct already defined by the kernel.
+ */
+#ifndef _UAPI_LIBC_COMPAT_H
+#define _UAPI_LIBC_COMPAT_H
+
+/* We have included glibc headers... */
+#if defined(__GLIBC__)
+
+/* Coordinate with glibc netinet/in.h header. */
+#if defined(_NETINET_IN_H)
+
+/* GLIBC headers included first so don't define anything
+ * that would already be defined. */
+#define __UAPI_DEF_IN6_ADDR             0
+/* The exception is the in6_addr macros which must be defined
+ * if the glibc code didn't define them. This guard matches
+ * the guard in glibc/inet/netinet/in.h which defines the
+ * additional in6_addr macros e.g. s6_addr16, and s6_addr32. */
+#if defined(__USE_MISC) || defined (__USE_GNU)
+#define __UAPI_DEF_IN6_ADDR_ALT         0
+#else
+#define __UAPI_DEF_IN6_ADDR_ALT         1
+#endif
+#define __UAPI_DEF_SOCKADDR_IN6         0
+#define __UAPI_DEF_IPV6_MREQ            0
+#define __UAPI_DEF_IPPROTO_V6           0
+
+#else
+
+/* Linux headers included first, and we must define everything
+ * we need. The expectation is that glibc will check the
+ * __UAPI_DEF_* defines and adjust appropriately. */
+#define __UAPI_DEF_IN6_ADDR             1
+/* We unconditionally define the in6_addr macros and glibc must
+ * coordinate. */
+#define __UAPI_DEF_IN6_ADDR_ALT         1
+#define __UAPI_DEF_SOCKADDR_IN6         1
+#define __UAPI_DEF_IPV6_MREQ            1
+#define __UAPI_DEF_IPPROTO_V6           1
+
+#endif /* _NETINET_IN_H */
+
+
+/* If we did not see any headers from any supported C libraries,
+ * or we are being included in the kernel, then define everything
+ * that we need. */
+#else /* !defined(__GLIBC__) */
+
+/* Definitions for in6.h */
+#define __UAPI_DEF_IN6_ADDR             1
+#define __UAPI_DEF_IN6_ADDR_ALT         1
+#define __UAPI_DEF_SOCKADDR_IN6         1
+#define __UAPI_DEF_IPV6_MREQ            1
+#define __UAPI_DEF_IPPROTO_V6           1
+
+#endif /* __GLIBC__ */
+
+#endif /* _UAPI_LIBC_COMPAT_H */