Attachment 56996 Details for Bug 35230 – transport: add new unixexec transport on Unix

[patch] transport: add new unixexec transport on Unix

0001-transport-add-new-unixexec-transport-on-Unix.patch (text/plain), 13.59 KB, created by Lennart Poettering on 2012-02-13 14:45:48 UTC

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Creator: Lennart Poettering

Created: 2012-02-13 14:45:48 UTC

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patch

obsolete

>From 86c4ebd17a12f42af3d29bbfa390fab3c6c84ce0 Mon Sep 17 00:00:00 2001
>From: Lennart Poettering <lennart@poettering.net>
>Date: Fri, 11 Mar 2011 22:35:16 +0100
>Subject: [PATCH] transport: add new unixexec transport on Unix
>
>The "unixexec:" transport will create a local AF_UNIX socket with
>socketpair(), then fork and execute a binary on one side with STDIN and
>STDOUT connected to it and then use the other side.
>
>This is useful to implement D-Bus tunneling schemes, for example to get
>a D-Bus connection to the system bus on a different host, similar how
>udisks is already doing it. (udisks uses SSH TCP tunneling for this,
>which is a bit ugly and less secure than this solution).
>
>Suggested use is with connection strings like the following:
>
>  unixexec:path=ssh,argv1=foobar,argv2=system-bus-bridge
>
>or:
>
>  unixexec:path=pkexec,argv1=system-bus-bridge
>
>or even:
>
>  unixexec:path=sudo,argv1=system-bus-bridge
>
>The first line would execute the binary 'system-bus-bridge' on host
>'foobar' and then pass D-Bus traffic to it. This (hypothetical) bridge
>binary would then forward the information to the local system bus.
>
>The second and third line use this scheme locally to acquire a
>privileged connection through pkexec resp. sudo: instead of connecting
>directly to the bus, they use the same bridge binary which will forward
>all information to the system bus.
>
>The arguments of the protocol are 'path' for the first execlp()
>argument, and argv0, argv1, and so on for the following arguments. argv0
>can be left out in which case path will be used.
>---
> dbus/dbus-connection-internal.h |    4 +
> dbus/dbus-connection.c          |   14 +++
> dbus/dbus-sysdeps-unix.c        |   90 +++++++++++++++++
> dbus/dbus-sysdeps-unix.h        |    4 +
> dbus/dbus-test.c                |    2 +
> dbus/dbus-test.h                |    1 +
> dbus/dbus-transport-unix.c      |  211 ++++++++++++++++++++++++++++++++++++++-
> 7 files changed, 325 insertions(+), 1 deletions(-)
>
>diff --git a/dbus/dbus-connection-internal.h b/dbus/dbus-connection-internal.h
>index ac4158e..3d37f18 100644
>--- a/dbus/dbus-connection-internal.h
>+++ b/dbus/dbus-connection-internal.h
>@@ -114,6 +114,10 @@ void _dbus_connection_get_stats (DBusConnection *connection,
>                                  dbus_uint32_t  *out_peak_bytes,
>                                  dbus_uint32_t  *out_peak_fds);
> 
>+
>+/* if DBUS_BUILD_TESTS */
>+const char* _dbus_connection_get_address (DBusConnection *connection);
>+
> /* This _dbus_bus_* stuff doesn't really belong here, but dbus-bus-internal.h seems
>  * silly for one function
>  */
>diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c
>index b8f48ad..681832d 100644
>--- a/dbus/dbus-connection.c
>+++ b/dbus/dbus-connection.c
>@@ -6258,4 +6258,18 @@ dbus_connection_get_outgoing_unix_fds (DBusConnection *connection)
>   return res;
> }
> 
>+#ifdef DBUS_BUILD_TESTS
>+/**
>+ * Returns the address of the transport object of this connection
>+ *
>+ * @param connection the connection
>+ * @returns the address string
>+ */
>+const char*
>+_dbus_connection_get_address (DBusConnection *connection)
>+{
>+  return _dbus_transport_get_address (connection->transport);
>+}
>+#endif
>+
> /** @} */
>diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
>index c587462..0aa54aa 100644
>--- a/dbus/dbus-sysdeps-unix.c
>+++ b/dbus/dbus-sysdeps-unix.c
>@@ -866,6 +866,96 @@ _dbus_connect_unix_socket (const char     *path,
> }
> 
> /**
>+ * Creates a UNIX domain socket and connects it to the specified
>+ * process to execute.
>+ *
>+ * This will set FD_CLOEXEC for the socket returned.
>+ *
>+ * @param path the path to the executable
>+ * @param argv the argument list for the process to execute.
>+ * argv[0] typically is identical to the path of the executable
>+ * @param error return location for error code
>+ * @returns connection file descriptor or -1 on error
>+ */
>+int
>+_dbus_connect_exec (const char     *path,
>+                    char *const    argv[],
>+                    DBusError      *error)
>+{
>+  int fds[2];
>+  pid_t pid;
>+
>+  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
>+
>+  _dbus_verbose ("connecting to process %s\n", path);
>+
>+  if (socketpair (AF_UNIX, SOCK_STREAM
>+#ifdef SOCK_CLOEXEC
>+                  |SOCK_CLOEXEC
>+#endif
>+                  , 0, fds) < 0)
>+    {
>+      dbus_set_error (error,
>+                      _dbus_error_from_errno (errno),
>+                      "Failed to create socket pair: %s",
>+                      _dbus_strerror (errno));
>+      return -1;
>+    }
>+
>+  _dbus_fd_set_close_on_exec (fds[0]);
>+  _dbus_fd_set_close_on_exec (fds[1]);
>+
>+  pid = fork ();
>+  if (pid < 0)
>+    {
>+      dbus_set_error (error,
>+                      _dbus_error_from_errno (errno),
>+                      "Failed to fork() to call %s: %s",
>+                      path, _dbus_strerror (errno));
>+      close (fds[0]);
>+      close (fds[1]);
>+      return -1;
>+    }
>+
>+  if (pid == 0)
>+    {
>+      /* child */
>+      close (fds[0]);
>+
>+      dup2 (fds[1], STDIN_FILENO);
>+      dup2 (fds[1], STDOUT_FILENO);
>+
>+      if (fds[1] != STDIN_FILENO &&
>+          fds[1] != STDOUT_FILENO)
>+        close (fds[1]);
>+
>+      /* Inherit STDERR and the controlling terminal from the
>+         parent */
>+
>+      _dbus_close_all ();
>+
>+      execvp (path, argv);
>+
>+      fprintf (stderr, "Failed to execute process %s: %s\n", path, _dbus_strerror (errno));
>+
>+      _exit(1);
>+    }
>+
>+  /* parent */
>+  close (fds[1]);
>+
>+  if (!_dbus_set_fd_nonblocking (fds[0], error))
>+    {
>+      _DBUS_ASSERT_ERROR_IS_SET (error);
>+
>+      close (fds[0]);
>+      return -1;
>+    }
>+
>+  return fds[0];
>+}
>+
>+/**
>  * Enables or disables the reception of credentials on the given socket during
>  * the next message transmission.  This is only effective if the #LOCAL_CREDS
>  * system feature exists, in which case the other side of the connection does
>diff --git a/dbus/dbus-sysdeps-unix.h b/dbus/dbus-sysdeps-unix.h
>index fbe5259..9b70896 100644
>--- a/dbus/dbus-sysdeps-unix.h
>+++ b/dbus/dbus-sysdeps-unix.h
>@@ -70,6 +70,10 @@ int _dbus_listen_unix_socket  (const char     *path,
>                                dbus_bool_t     abstract,
>                                DBusError      *error);
> 
>+int _dbus_connect_exec (const char     *path,
>+                        char *const    argv[],
>+                        DBusError      *error);
>+
> int _dbus_listen_systemd_sockets (int       **fd,
>                                  DBusError *error);
> 
>diff --git a/dbus/dbus-test.c b/dbus/dbus-test.c
>index 02eaf89..224a6c8 100644
>--- a/dbus/dbus-test.c
>+++ b/dbus/dbus-test.c
>@@ -154,6 +154,8 @@ dbus_internal_do_not_use_run_tests (const char *test_data_dir, const char *speci
> 
> #ifdef DBUS_UNIX
>   run_data_test ("userdb", specific_test, _dbus_userdb_test, test_data_dir);
>+
>+  run_test ("transport-unix", specific_test, _dbus_transport_unix_test);
> #endif
>   
>   run_test ("keyring", specific_test, _dbus_keyring_test);
>diff --git a/dbus/dbus-test.h b/dbus/dbus-test.h
>index d97d142..f254388 100644
>--- a/dbus/dbus-test.h
>+++ b/dbus/dbus-test.h
>@@ -48,6 +48,7 @@ dbus_bool_t _dbus_data_slot_test         (void);
> dbus_bool_t _dbus_sysdeps_test           (void);
> dbus_bool_t _dbus_spawn_test             (const char *test_data_dir);
> dbus_bool_t _dbus_userdb_test            (const char *test_data_dir);
>+dbus_bool_t _dbus_transport_unix_test    (void);
> dbus_bool_t _dbus_memory_test            (void);
> dbus_bool_t _dbus_object_tree_test       (void);
> dbus_bool_t _dbus_credentials_test       (const char *test_data_dir);
>diff --git a/dbus/dbus-transport-unix.c b/dbus/dbus-transport-unix.c
>index a47756f..6ba5c0b 100644
>--- a/dbus/dbus-transport-unix.c
>+++ b/dbus/dbus-transport-unix.c
>@@ -22,6 +22,9 @@
>  */
> 
> #include <config.h>
>+
>+#include <stdio.h>
>+
> #include "dbus-internals.h"
> #include "dbus-connection-internal.h"
> #include "dbus-transport-unix.h"
>@@ -29,6 +32,7 @@
> #include "dbus-transport-protected.h"
> #include "dbus-watch.h"
> #include "dbus-sysdeps-unix.h"
>+#include "dbus-test.h"
> 
> /**
>  * @defgroup DBusTransportUnix DBusTransport implementations for UNIX
>@@ -108,6 +112,108 @@ _dbus_transport_new_for_domain_socket (const char     *path,
> }
> 
> /**
>+ * Creates a new transport for the given binary and arguments. This
>+ * creates a client-side of a transport. The process will be forked
>+ * off and executed with stdin/stdout connected to a local AF_UNIX
>+ * socket.
>+ *
>+ * @param path the path to the domain socket.
>+ * @param argv Parameters list
>+ * @param error address where an error can be returned.
>+ * @returns a new transport, or #NULL on failure.
>+ */
>+static DBusTransport*
>+_dbus_transport_new_for_exec (const char     *path,
>+                              char *const     argv[],
>+                              DBusError      *error)
>+{
>+  int fd;
>+  DBusTransport *transport;
>+  DBusString address;
>+  unsigned i;
>+  char *escaped;
>+
>+  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
>+
>+  if (!_dbus_string_init (&address))
>+    {
>+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+      return NULL;
>+    }
>+
>+  fd = -1;
>+
>+  escaped = dbus_address_escape_value (path);
>+  if (!escaped)
>+    {
>+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+      goto failed;
>+    }
>+
>+  if (!_dbus_string_append (&address, "unixexec:path=") ||
>+      !_dbus_string_append (&address, escaped))
>+    {
>+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+      dbus_free (escaped);
>+      goto failed;
>+    }
>+
>+  dbus_free (escaped);
>+
>+  if (argv)
>+    {
>+      for (i = 0; argv[i]; i++)
>+        {
>+          dbus_bool_t success;
>+
>+          escaped = dbus_address_escape_value (argv[i]);
>+          if (!escaped)
>+            {
>+              dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+              goto failed;
>+            }
>+
>+          success = _dbus_string_append_printf (&address, ",argv%u=%s", i, escaped);
>+          dbus_free (escaped);
>+
>+          if (!success)
>+            {
>+              dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+              goto failed;
>+            }
>+        }
>+    }
>+
>+  fd = _dbus_connect_exec (path, argv, error);
>+  if (fd < 0)
>+    {
>+      _DBUS_ASSERT_ERROR_IS_SET (error);
>+      goto failed;
>+    }
>+
>+  _dbus_verbose ("Successfully connected to process %s\n",
>+                 path);
>+
>+  transport = _dbus_transport_new_for_socket (fd, NULL, &address);
>+  if (transport == NULL)
>+    {
>+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+      goto failed;
>+    }
>+
>+  _dbus_string_free (&address);
>+
>+  return transport;
>+
>+ failed:
>+  if (fd >= 0)
>+    _dbus_close_socket (fd, NULL);
>+
>+  _dbus_string_free (&address);
>+  return NULL;
>+}
>+
>+/**
>  * Opens platform specific transport types.
>  * 
>  * @param entry the address entry to try opening
>@@ -168,7 +274,81 @@ _dbus_transport_open_platform_specific (DBusAddressEntry  *entry,
>         {
>           _DBUS_ASSERT_ERROR_IS_CLEAR (error);
>           return DBUS_TRANSPORT_OPEN_OK;
>-        }      
>+        }
>+    }
>+  else if (strcmp (method, "unixexec") == 0)
>+    {
>+      const char *path;
>+      unsigned i;
>+      char **argv;
>+
>+      path = dbus_address_entry_get_value (entry, "path");
>+      if (path == NULL)
>+        {
>+          _dbus_set_bad_address (error, NULL, NULL,
>+                                 "No process path specified");
>+          return DBUS_TRANSPORT_OPEN_BAD_ADDRESS;
>+        }
>+
>+      /* First count argv arguments */
>+      for (i = 1; ; i++)
>+        {
>+          char t[4+20+1]; /* "argv" plus space for a formatted base 10 64bit integer, plus NUL */
>+
>+          snprintf (t, sizeof(t), "argv%u", i);
>+
>+          if (!dbus_address_entry_get_value (entry, t))
>+            break;
>+        }
>+
>+      /* Allocate string array */
>+      argv = dbus_new0 (char*, i+1);
>+      if (!argv)
>+        {
>+          dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+          return DBUS_TRANSPORT_OPEN_DID_NOT_CONNECT;
>+        }
>+
>+      /* Fill in string array */
>+      for (i = 0; ; i++)
>+        {
>+          char t[4+20+1];
>+          const char *p;
>+
>+          snprintf (t, sizeof(t), "argv%u", i);
>+
>+          p = dbus_address_entry_get_value (entry, t);
>+          if (!p)
>+            {
>+              if (i == 0)
>+                /* If argv0 isn't specified, fill in the path instead */
>+                p = path;
>+              else
>+                break;
>+            }
>+
>+          argv[i] = _dbus_strdup (p);
>+          if (!argv[i])
>+            {
>+              dbus_free_string_array (argv);
>+              dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
>+              return DBUS_TRANSPORT_OPEN_DID_NOT_CONNECT;
>+            }
>+        }
>+
>+      *transport_p = _dbus_transport_new_for_exec (path, argv, error);
>+      dbus_free_string_array (argv);
>+
>+      if (*transport_p == NULL)
>+        {
>+          _DBUS_ASSERT_ERROR_IS_SET (error);
>+          return DBUS_TRANSPORT_OPEN_DID_NOT_CONNECT;
>+        }
>+      else
>+        {
>+          _DBUS_ASSERT_ERROR_IS_CLEAR (error);
>+          return DBUS_TRANSPORT_OPEN_OK;
>+        }
>     }
> #ifdef DBUS_ENABLE_LAUNCHD
>   else if (strcmp (method, "launchd") == 0)
>@@ -231,3 +411,32 @@ _dbus_transport_open_platform_specific (DBusAddressEntry  *entry,
> }
> 
> /** @} */
>+
>+#ifdef DBUS_BUILD_TESTS
>+
>+dbus_bool_t
>+_dbus_transport_unix_test (void)
>+{
>+  DBusConnection *c;
>+  DBusError error;
>+  dbus_bool_t ret;
>+  const char *address;
>+
>+  dbus_error_init (&error);
>+
>+  c = dbus_connection_open ("unixexec:argv0=false,argv1=foobar,path=/bin/false", &error);
>+  _dbus_assert (c != NULL);
>+  _dbus_assert (!dbus_error_is_set (&error));
>+
>+  address = _dbus_connection_get_address (c);
>+  _dbus_assert (address != NULL);
>+
>+  /* Let's see if the address got parsed, reordered and formatted correctly */
>+  ret = strcmp (address, "unixexec:path=/bin/false,argv0=false,argv1=foobar") == 0;
>+
>+  dbus_connection_unref (c);
>+
>+  return ret;
>+}
>+
>+#endif
>-- 
>1.7.9
>

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Attachments on bug 35230: 44369 | 44371 | 49638 | 49639 | 50552 | 50553 | 50554 | 56495 | 56496 | 56841 | 56842 | 56995 | 56996

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