From 1b911148009f696717da0b676d6d10af85d5aefb Mon Sep 17 00:00:00 2001
From: Emilio Pozuelo Monfort <pochu27@gmail.com>
Date: Sat, 17 Jul 2010 22:09:13 +0200
Subject: [PATCH] Add support to send file descriptors over Unix sockets

---
 sysdeps/mach/hurd/recvmsg.c | 97 ++++++++++++++++++++++++++++++++++++++++++++-
 sysdeps/mach/hurd/sendmsg.c | 73 +++++++++++++++++++++++++++++-----
 2 files changed, 157 insertions(+), 13 deletions(-)

diff --git a/sysdeps/mach/hurd/recvmsg.c b/sysdeps/mach/hurd/recvmsg.c
index 5d7b1ee..dfd4145 100644
--- a/sysdeps/mach/hurd/recvmsg.c
+++ b/sysdeps/mach/hurd/recvmsg.c
@@ -32,13 +32,34 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
   addr_port_t aport;
   char *data = NULL;
   mach_msg_type_number_t len = 0;
-  mach_port_t *ports;
+  mach_port_t *ports, *newports = NULL;
   mach_msg_type_number_t nports = 0;
+  struct cmsghdr *cmsg;
   char *cdata = NULL;
   mach_msg_type_number_t clen = 0;
   size_t amount;
   char *buf;
-  int i;
+  int nfds, *opened_fds = NULL;
+  int i, ii, j;
+  int newfds;
+
+  error_t reauthenticate (mach_port_t port, mach_port_t *result)
+    {
+      error_t err;
+      mach_port_t ref;
+      ref = __mach_reply_port ();
+      do
+	err = __io_reauthenticate (port, ref, MACH_MSG_TYPE_MAKE_SEND);
+      while (err == EINTR);
+      if (!err)
+	do
+	  err = __USEPORT (AUTH, __auth_user_authenticate (port,
+					  ref, MACH_MSG_TYPE_MAKE_SEND,
+					  result));
+	while (err == EINTR);
+      __mach_port_destroy (__mach_task_self (), ref);
+      return err;
+    }
 
   /* Find the total number of bytes to be read.  */
   amount = 0;
@@ -135,9 +156,81 @@ __libc_recvmsg (int fd, struct msghdr *message, int flags)
     message->msg_controllen = clen;
   memcpy (message->msg_control, cdata, message->msg_controllen);
 
+  if (nports > 0)
+    {
+      newports = __alloca (nports * sizeof (mach_port_t));
+      opened_fds = __alloca (nports * sizeof (int));
+    }
+
+  /* This counts how many ports we processed completely.  */
+  i = 0;
+  /* This counts how many new fds we create.  */
+  newfds = 0;
+
+  for (cmsg = CMSG_FIRSTHDR (message);
+       cmsg;
+       cmsg = CMSG_NXTHDR (message, cmsg))
+  {
+    if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
+      {
+	/* SCM_RIGHTS support.  */
+	/* The fd's flags are passed in the control data.  */
+	int *fds = (int *) CMSG_DATA (cmsg);
+	nfds = (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
+	       / sizeof (int);
+
+	for (j = 0; j < nfds; j++)
+	  {
+	    err = reauthenticate (ports[i], &newports[newfds]);
+	    if (err)
+	      goto cleanup;
+	    fds[j] = opened_fds[newfds] = _hurd_intern_fd (newports[newfds],
+							   fds[j], 0);
+	    if (fds[j] == -1)
+	      {
+		err = errno;
+		__mach_port_deallocate (__mach_task_self (), newports[newfds]);
+		goto cleanup;
+	      }
+	    i++;
+	    newfds++;
+	  }
+      }
+  }
+
+  for (i = 0; i < nports; i++)
+    __mach_port_deallocate (mach_task_self (), ports[i]);
+
   __vm_deallocate (__mach_task_self (), (vm_address_t) cdata, clen);
 
   return (buf - data);
+
+cleanup:
+  /* Clean up all the file descriptors from port 0 to i-1.  */
+  if (nports > 0)
+    {
+      ii = 0;
+      newfds = 0;
+      for (cmsg = CMSG_FIRSTHDR (message);
+	   cmsg;
+	   cmsg = CMSG_NXTHDR (message, cmsg))
+	{
+	  if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
+	    {
+	      nfds = (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
+		     / sizeof (int);
+	      for (j = 0; j < nfds && ii < i; j++, ii++, newfds++)
+	      {
+		_hurd_fd_close (_hurd_fd_get (opened_fds[newfds]));
+		__mach_port_deallocate (__mach_task_self (), newports[newfds]);
+		__mach_port_deallocate (__mach_task_self (), ports[ii]);
+	      }
+	    }
+	}
+    }
+
+  __vm_deallocate (__mach_task_self (), (vm_address_t) cdata, clen);
+  return __hurd_fail (err);
 }
 
 weak_alias (__libc_recvmsg, recvmsg)
diff --git a/sysdeps/mach/hurd/sendmsg.c b/sysdeps/mach/hurd/sendmsg.c
index 5a93c63..612581c 100644
--- a/sysdeps/mach/hurd/sendmsg.c
+++ b/sysdeps/mach/hurd/sendmsg.c
@@ -31,6 +31,10 @@ ssize_t
 __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 {
   error_t err = 0;
+  struct cmsghdr *cmsg;
+  mach_port_t *ports = NULL;
+  mach_msg_type_number_t nports = 0;
+  int *fds, nfds;
   struct sockaddr_un *addr = message->msg_name;
   socklen_t addr_len = message->msg_namelen;
   addr_port_t aport = MACH_PORT_NULL;
@@ -43,6 +47,7 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
   mach_msg_type_number_t len;
   mach_msg_type_number_t amount;
   int dealloc = 0;
+  int socketrpc = 0;
   int i;
 
   /* Find the total number of bytes to be written.  */
@@ -100,6 +105,48 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 	}
     }
 
+  /* Allocate enough room for ports.  */
+  cmsg = CMSG_FIRSTHDR (message);
+  for (; cmsg; cmsg = CMSG_NXTHDR (message, cmsg))
+    if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
+      nports += (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
+		/ sizeof (int);
+
+  if (nports)
+    ports = __alloca (nports * sizeof (mach_port_t));
+
+  nports = 0;
+  for (cmsg = CMSG_FIRSTHDR (message);
+       cmsg;
+       cmsg = CMSG_NXTHDR (message, cmsg))
+    {
+      if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
+	{
+	  /* SCM_RIGHTS support: send FDs.   */
+	  fds = (int *) CMSG_DATA (cmsg);
+	  nfds = (cmsg->cmsg_len - CMSG_ALIGN (sizeof (struct cmsghdr)))
+		 / sizeof (int);
+
+	  for (i = 0; i < nfds; i++)
+	    {
+	      err = HURD_DPORT_USE
+		(fds[i],
+		 ({
+		   err = __io_restrict_auth (port, &ports[nports],
+					     0, 0, 0, 0);
+		   if (! err)
+		     nports++;
+		   /* We pass the flags in the control data.  */
+		   fds[i] = descriptor->flags;
+		   err;
+		 }));
+
+	      if (err)
+		goto out;
+	    }
+	}
+    }
+
   if (addr)
     {
       if (addr->sun_family == AF_LOCAL)
@@ -109,9 +156,8 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 	  file_t file = __file_name_lookup (name, 0, 0);
 	  if (file == MACH_PORT_NULL)
 	    {
-	      if (dealloc)
-		__vm_deallocate (__mach_task_self (), data.addr, len);
-	      return -1;
+	      err = errno;
+	      goto out;
 	    }
 	  err = __ifsock_getsockaddr (file, &aport);
 	  __mach_port_deallocate (__mach_task_self (), file);
@@ -119,11 +165,7 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 	    /* The file did not grok the ifsock protocol.  */
 	    err = ENOTSOCK;
 	  if (err)
-	    {
-	      if (dealloc)
-		__vm_deallocate (__mach_task_self (), data.addr, len);
-	      return __hurd_fail (err);
-	    }
+	    goto out;
 	}
       else
 	err = EIEIO;
@@ -142,8 +184,9 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 			      /* Send the data.  */
 			      err = __socket_send (port, aport,
 						   flags, data.ptr, len,
-						   NULL,
-						   MACH_MSG_TYPE_COPY_SEND, 0,
+						   ports,
+						   MACH_MSG_TYPE_COPY_SEND,
+						   nports,
 						   message->msg_control,
 						   message->msg_controllen,
 						   &amount);
@@ -152,11 +195,19 @@ __libc_sendmsg (int fd, const struct msghdr *message, int flags)
 			    }
 			  err;
 			}));
+  socketrpc = 1;
+
+ out:
+  for (i = 0; i < nports; i++)
+    __mach_port_deallocate (__mach_task_self (), ports[i]);
 
   if (dealloc)
     __vm_deallocate (__mach_task_self (), data.addr, len);
 
-  return err ? __hurd_sockfail (fd, flags, err) : amount;
+  if (socketrpc)
+    return err ? __hurd_sockfail (fd, flags, err) : amount;
+  else
+    return __hurd_fail (err);
 }
 
 weak_alias (__libc_sendmsg, sendmsg)
-- 
tg: (b4578ba..) t/sendmsg-SCM_RIGHTS (depends on: 64a17f1adde4715bb6607f64decd73b2df9e6852)