network: recvmmsg and sendmmsg standard compliance (BZ#16919)

POSIX specifies that both msghdr::msg_iovlen and msghdr::msg_controllen
to be of size int and socklen_t respectively, however Linux implements
it as a size_t.  So for 64-bits architecture where sizeof of size_t is
larger than socklen_t, both sendmmsg and recvmmsg need to adjust the
mmsghdr::msg_hdr internal fields before issuing the syscall itself.

This patch fixes it by operating on the padding if it the case.
For recvmmsg, the most straightfoward case, only zero padding the fields
is suffice.  However, for sendmmsg, where adjusting the buffer is out
of the contract (since it may point to a read-only data), the function
is rewritten to use sendmsg instead (which from previous patch
allocates a temporary msghdr to operate on).

Also for 64-bit ports that requires it, a new recvmmsg and sendmmsg
compat version is created (which uses size_t for both cmsghdr::cmsg_len
and internal

Tested on x86_64, i686, aarch64, armhf, and powerpc64le.

	* sysdeps/unix/sysv/linux/Makefile
	[$(subdir) = socket] (sysdep_routines): Add oldrecvmmsg and
	oldsendmmsg.
	* sysdeps/unix/sysv/linux/aarch64/libc.abilist: Add recvmmsg and
	sendmmsg.
	* sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise.
	* sysdeps/sysv/linux/powerpc/powerpc64/libc-le.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist:
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/oldrecvmmsg.c: New file.
	* sysdeps/unix/sysv/linux/oldsendmmsg.c: Likewise.
	* sysdeps/unix/sysv/linux/recvmmsg.c (__recvmmsg): Adjust msghdr
	iovlen and controllen fields to adjust to POSIX specification.
	* sysdeps/unix/sysv/linux/sendmmsg.c (__sendmmsg): Likewise.

1 files changed, 39 insertions, 22 deletions

diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
index bf18260b46..08b89ba962 100644
--- a/sysdeps/unix/sysv/linux/recvmmsg.c
+++ b/sysdeps/unix/sysv/linux/recvmmsg.c
@@ -16,12 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <sys/socket.h>
-
+#include <socketcall.h>
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-#include <kernel-features.h>
+#include <shlib-compat.h>
 
 /* Do not use the recvmmsg syscall on socketcall architectures unless
    it was added at the same time as the socketcall support or can be
@@ -32,31 +30,39 @@
 # undef __NR_recvmmsg
 #endif
 
-#ifdef __NR_recvmmsg
+static inline void
+adjust_mmsghdr (struct mmsghdr *vmessages, unsigned int vlen)
+{
+#if __WORDSIZE == 64
+  /* POSIX specifies that both msghdr::msg_iovlen and msghdr::msg_controllen
+     to be int and socklen_t respectively.  However Linux defines it as
+     both size_t.  So for 64-bit it requires some adjustments by zeroing
+     the pad fields.  */
+  struct mmsghdr *vmhdr = vmessages;
+  for (unsigned int i = 0; i != 0; i--, vmhdr++)
+    {
+      vmhdr->msg_hdr.__glibc_reserved1 = 0;
+      vmhdr->msg_hdr.__glibc_reserved2 = 0;
+    }
+#endif
+}
+
 int
-recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
-	  struct timespec *tmo)
+__recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen,
+		 int flags, struct timespec *tmo)
 {
+#ifdef __NR_recvmmsg
+  adjust_mmsghdr (vmessages, vlen);
   return SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
-}
 #elif defined __NR_socketcall
-# include <socketcall.h>
 # ifdef __ASSUME_RECVMMSG_SOCKETCALL
-int
-recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
-	  struct timespec *tmo)
-{
+  adjust_mmsghdr (vmessages, vlen);
   return SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
-}
 # else
-static int have_recvmmsg;
-
-int
-recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
-	  struct timespec *tmo)
-{
+  static int have_recvmmsg;
   if (__glibc_likely (have_recvmmsg >= 0))
     {
+      adjust_mmsghdr (vmessages, vlen);
       int ret = SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags,
 				   tmo);
       /* The kernel returns -EINVAL for unknown socket operations.
@@ -86,8 +92,19 @@ recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
     }
   __set_errno (ENOSYS);
   return -1;
-}
 # endif /* __ASSUME_RECVMMSG_SOCKETCALL  */
 #else
-# include <socket/recvmmsg.c>
+# define STUB 1
+  __set_errno (ENOSYS);
+  return -1;
+#endif
+}
+#ifdef STUB
+stub_warning (recvmmsg)
+#endif
+
+#if __WORDSIZE == 64
+versioned_symbol (libc, __recvmmsg, recvmmsg, GLIBC_2_24);
+#else
+weak_alias (__recvmmsg, recvmmsg)
 #endif