pluggable auth with plugin examples

Makefile.am:
  add new API files to the check_abi rule,
  remove duplicates
client/CMakeLists.txt:
  now a client can use dlopen too
client/Makefile.am:
  be csh-friendly
include/my_global.h:
  add dummy plugs for dlopen and co.
  for the code that needs them to work in static builds
mysys/Makefile.am:
  be csh-friendly
plugin/auth/dialog.c:
  typo fixed

4 files changed, 434 insertions, 0 deletions

diff --git a/plugin/auth/Makefile.am b/plugin/auth/Makefile.am
new file mode 100644
index 00000000000..acca98e26f8
--- /dev/null
+++ b/plugin/auth/Makefile.am
@@ -0,0 +1,15 @@
+pkgplugindir=$(pkglibdir)/plugin
+
+AM_LDFLAGS=-module -rpath $(pkgplugindir)
+AM_CPPFLAGS=-DMYSQL_DYNAMIC_PLUGIN -I$(top_srcdir)/include
+
+pkgplugin_LTLIBRARIES=  dialog.la
+dialog_la_SOURCES= dialog.c
+
+if HAVE_PEERCRED
+pkgplugin_LTLIBRARIES+= auth_socket.la
+auth_socket_la_SOURCES= auth_socket.c
+endif
+
+EXTRA_DIST= plug.in
+
diff --git a/plugin/auth/auth_socket.c b/plugin/auth/auth_socket.c
new file mode 100644
index 00000000000..42b9f7528b6
--- /dev/null
+++ b/plugin/auth/auth_socket.c
@@ -0,0 +1,102 @@
+/* Copyright (C) 2010 Sergei Golubchik and Monty Program Ab
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+/**
+  @file
+
+  socket_peercred authentication plugin.
+
+  Authentication is successful if the connection is done via a unix socket and
+  the owner of the client process matches the user name that was used when
+  connecting to mysqld.
+*/
+#define _GNU_SOURCE /* for struct ucred */
+
+#include <mysql/plugin_auth.h>
+#include <sys/socket.h>
+#include <pwd.h>
+#include <string.h>
+
+/**
+  perform the unix socket based authentication
+
+  This authentication callback performs a unix socket based authentication -
+  it gets the uid of the client process and considers the user authenticated
+  if it uses username of this uid. That is - if the user is already
+  authenticated to the OS (if she is logged in) - she can use MySQL as herself
+*/
+
+static int socket_auth(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info)
+{
+  unsigned char *pkt;
+  MYSQL_PLUGIN_VIO_INFO vio_info;
+  struct ucred cred;
+  socklen_t cred_len= sizeof(cred);
+  struct passwd pwd_buf, *pwd;
+  char buf[1024];
+
+  /* no user name yet ? read the client handshake packet with the user name */
+  if (info->user_name == 0)
+  {
+    if (vio->read_packet(vio, &pkt) < 0)
+      return CR_ERROR;
+  }
+
+  info->password_used = 0;
+
+  vio->info(vio, &vio_info);
+  if (vio_info.protocol != MYSQL_VIO_SOCKET)
+    return CR_ERROR;
+
+  /* get the UID of the client process */
+  if (getsockopt(vio_info.socket, SOL_SOCKET, SO_PEERCRED, &cred, &cred_len))
+    return CR_ERROR;
+
+  if (cred_len != sizeof(cred))
+    return CR_ERROR;
+
+  /* and find the username for this uid */
+  getpwuid_r(cred.uid, &pwd_buf, buf, sizeof(buf), &pwd);
+  if (pwd == NULL)
+    return CR_ERROR;
+
+  /* now it's simple as that */
+  return strcmp(pwd->pw_name, info->user_name) ? CR_ERROR : CR_OK;
+}
+
+static struct st_mysql_auth socket_auth_handler=
+{
+  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
+  0,
+  socket_auth
+};
+
+mysql_declare_plugin(socket_auth)
+{
+  MYSQL_AUTHENTICATION_PLUGIN,
+  &socket_auth_handler,
+  "socket_peercred",
+  "Sergei Golubchik",
+  "Unix Socket based authentication",
+  PLUGIN_LICENSE_GPL,
+  NULL,
+  NULL,
+  0x0100,
+  NULL,
+  NULL,
+  NULL
+}
+mysql_declare_plugin_end;
+
diff --git a/plugin/auth/dialog.c b/plugin/auth/dialog.c
new file mode 100644
index 00000000000..71dc2239fd0
--- /dev/null
+++ b/plugin/auth/dialog.c
@@ -0,0 +1,302 @@
+/* Copyright (C) 2010 Sergei Golubchik and Monty Program Ab
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+/**
+  @file
+
+  dialog client authentication plugin with examples
+
+  dialog is a general purpose client authentication plugin, it simply
+  asks the user the question, as provided by the server and reports
+  the answer back to the server. No encryption is involved,
+  the answers are sent in clear text.
+
+  Two examples are provided: two_questions server plugin, that asks
+  the password and an "Are you sure?" question with a reply "yes, of course".
+  It demonstrates the usage of "password" (input is hidden) and "ordinary"
+  (input can be echoed) questions, and how to mark the last question,
+  to avoid an extra roundtrip.
+
+  And three_attempts plugin that gives the user three attempts to enter
+  a correct password. It shows the situation when a number of questions
+  is not known in advance.
+*/
+#define _GNU_SOURCE /* for RTLD_DEFAULT */
+
+#include <mysql/plugin_auth.h>
+#include <mysql/client_plugin.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/**
+  first byte of the question string is the question "type".
+  It can be a "ordinary" or a "password" question.
+  The last bit set marks a last question in the authentication exchange.
+*/
+#define ORDINARY_QUESTION       "\2"
+#define LAST_QUESTION           "\3"
+#define PASSWORD_QUESTION       "\4"
+#define LAST_PASSWORD           "\5"
+
+/********************* SERVER SIDE ****************************************/
+
+/**
+  dialog demo with two questions, one password and one ordinary.
+*/
+
+static int two_questions(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info)
+{
+  unsigned char *pkt;
+  int pkt_len;
+
+  /* send a password question */
+  if (vio->write_packet(vio, PASSWORD_QUESTION "Password, please:", 18))
+    return CR_ERROR;
+
+  /* read the answer */
+  if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+    return CR_ERROR;
+
+  info->password_used = 1;
+
+  /* fail if the password is wrong */
+  if (strcmp(pkt, info->auth_string))
+    return CR_ERROR;
+
+  /* send the last, ordinary, question */
+  if (vio->write_packet(vio, LAST_QUESTION "Are you sure ?", 15))
+    return CR_ERROR;
+
+  /* read the answer */
+  if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+    return CR_ERROR;
+
+  /* check the reply */
+  return strcmp(pkt, "yes, of course") ? CR_ERROR : CR_OK;
+}
+
+static struct st_mysql_auth two_handler=
+{
+  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
+  "dialog", /* requires dialog client plugin */
+  two_questions
+};
+
+
+/**
+  dialog demo where the number of questions is not known in advance
+*/
+
+static int three_attempts(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info)
+{
+  unsigned char *pkt;
+  int pkt_len, i;
+
+  for (i= 0; i < 3; i++)
+  {
+    /* send the prompt */
+    if (vio->write_packet(vio, PASSWORD_QUESTION "Password, please:", 18))
+      return CR_ERROR;
+
+    /* read the password */
+    if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+      return CR_ERROR;
+
+    info->password_used = 1;
+
+    /*
+      finish, if the password is correct.
+      note, that we did not mark the prompt packet as "last"
+    */
+    if (strcmp(pkt, info->auth_string) == 0)
+      return CR_OK;
+  }
+
+  return CR_ERROR;
+}
+
+static struct st_mysql_auth three_handler=
+{
+  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
+  "dialog", /* requires dialog client plugin */
+  three_attempts 
+};
+
+mysql_declare_plugin(dialog)
+{
+  MYSQL_AUTHENTICATION_PLUGIN,
+  &two_handler,
+  "two_questions",
+  "Sergei Golubchik",
+  "Dialog plugin demo 1",
+  PLUGIN_LICENSE_GPL,
+  NULL,
+  NULL,
+  0x0100,
+  NULL,
+  NULL,
+  NULL
+},
+{
+  MYSQL_AUTHENTICATION_PLUGIN,
+  &three_handler,
+  "three_attempts",
+  "Sergei Golubchik",
+  "Dialog plugin demo 2",
+  PLUGIN_LICENSE_GPL,
+  NULL,
+  NULL,
+  0x0100,
+  NULL,
+  NULL,
+  NULL
+}
+mysql_declare_plugin_end;
+
+/********************* CLIENT SIDE ***************************************/
+/*
+  This plugin performs a dialog with the user, asking questions and
+  reading answers. Depending on the client it may be desirable to do it
+  using GUI, or console, with or without curses, or read answers
+  from a smardcard, for example.
+
+  To support all this variety, the dialog plugin has a callback function
+  "authentication_dialog_ask". If the client has a function of this name
+  dialog plugin will use it for communication with the user. Otherwise
+  a default gets() based implementation will be used.
+*/
+#include <mysql.h>
+#include <dlfcn.h>
+
+static mysql_authentication_dialog_ask_t ask;
+
+static char *builtin_ask(MYSQL *mysql __attribute__((unused)),
+                         int type __attribute__((unused)),
+                         const char *prompt,
+                         char *buf, int buf_len __attribute__((unused)))
+{
+  fputs(prompt, stdout);
+  fputc(' ', stdout);
+  if (gets(buf) == 0)
+    return 0;
+
+  return buf;
+}
+
+
+/**
+  The main function of the dialog plugin.
+
+  Read the prompt, ask the question, send the reply, repeat until
+  the server is satisfied.
+
+  @note
+   1. this plugin shows how a client authentication plugin
+      may read a MySQL protocol OK packet internally - which is important
+      where a number of packets is not known in advance.
+   2. the first byte of the prompt is special. it is not
+      shown to the user, but signals whether it is the last question
+      (prompt[0] & 1 == 1) or not last (prompt[0] & 1 == 0),
+      and whether the input is a password (not echoed).
+   3. the prompt is expected to be sent zero-terminated
+*/
+
+static int perform_dialog(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql)
+{
+  unsigned char *pkt, cmd= 0;
+  int pkt_len, res;
+  char reply_buf[1024], *reply;
+
+  do
+  {
+    /* read the prompt */
+    pkt_len= vio->read_packet(vio, &pkt);
+    if (pkt_len < 0)
+      return CR_ERROR;
+
+    if (pkt == 0)
+    {
+      /*
+        in mysql_change_user() the client sends the first packet, so
+        the first vio->read_packet() does nothing (pkt == 0).
+
+        We send the "password", assuming the client knows what its doing.
+        (in other words, the dialog plugin should be only set as a default
+        authentication plugin on the client if the first question
+        asks for a password - which will be sent in clear text, by the way)
+      */
+      reply= mysql->passwd;
+    }
+    else
+    {
+      cmd= *pkt++;
+
+      /* is it MySQL protocol packet ? */
+      if (cmd == 0 || cmd == 254)
+        return CR_OK_HANDSHAKE_COMPLETE; /* yes. we're done */
+
+      /*
+        asking for a password with an empty prompt means mysql->password
+        otherwise we ask the user and read the reply
+      */
+      if ((cmd >> 1) == 2 && *pkt == 0)
+        reply= mysql->passwd;
+      else
+        reply= ask(mysql, cmd >> 1, pkt, reply_buf, sizeof(reply_buf));
+      if (!reply)
+        return CR_ERROR;
+    }
+    /* send the reply to the server */
+    res= vio->write_packet(vio, reply, strlen(reply)+1);
+
+    if (reply != mysql->passwd && reply != reply_buf)
+      free(reply);
+
+    if (res)
+      return CR_ERROR;
+
+    /* repeat unless it was the last question */
+  } while ((cmd & 1) != 1);
+
+  /* the job of reading the ok/error packet is left to the server */
+  return CR_OK;
+}
+
+
+/**
+  initialization function of the dialog plugin
+
+  Pick up the client's authentication_dialog_ask() function, if exists,
+  or fall back to the default implementation.
+*/
+
+static int init_dialog()
+{
+  void *sym= dlsym(RTLD_DEFAULT, "mysql_authentication_dialog_ask");
+  ask= sym ? (mysql_authentication_dialog_ask_t)sym : builtin_ask;
+  return 0;
+}
+
+mysql_declare_client_plugin(AUTHENTICATION)
+  "dialog",
+  "Sergei Golubchik",
+  "Dialog Client Authentication Plugin",
+  {0,1,0},
+  init_dialog,
+  NULL,
+  perform_dialog
+mysql_end_client_plugin;
+
diff --git a/plugin/auth/plug.in b/plugin/auth/plug.in
new file mode 100644
index 00000000000..ce31465b056
--- /dev/null
+++ b/plugin/auth/plug.in
@@ -0,0 +1,15 @@
+MYSQL_PLUGIN(auth, [Collection of Authentication Plugins],
+                   [Collection of Authentication Plugins])
+MYSQL_PLUGIN_DYNAMIC(auth, [dialog.la])
+MYSQL_PLUGIN_ACTIONS(auth,[
+AC_COMPILE_IFELSE([
+  AC_LANG_PROGRAM([[
+#define _GNU_SOURCE
+#include <sys/socket.h>
+]],[[
+  struct ucred cred;
+  getsockopt(0, SOL_SOCKET, SO_PEERCRED, &cred, 0);
+]])],have_peercred=yes)
+AM_CONDITIONAL(HAVE_PEERCRED, test x$have_peercred = xyes)
+])
+AM_CONDITIONAL(HAVE_PEERCRED, false)