debian/patches/90_localscan_dlopen.dpatch

   1 Description: Allow one to use and switch between different local_scan functions
   2  without recompiling exim.
   3  http://marc.merlins.org/linux/exim/files/sa-exim-current/ Original patch from
   4  David Woodhouse, modified first by Derrick 'dman' Hudson and then by Marc
   5  MERLIN for SA-Exim and minor/major API version tracking
   6 Author: David Woodhouse, Derrick 'dman' Hudson, Marc MERLIN
   7 Origin: other, http://marc.merlins.org/linux/exim/files/sa-exim-current/
   8 Forwarded: no
   9 Last-Update: 2018-12-12
  10
  11 --- a/src/EDITME
  12 +++ b/src/EDITME
  13 @@ -824,6 +824,21 @@ HEADERS_CHARSET="ISO-8859-1"
  14
  15
  16  #------------------------------------------------------------------------------
  17 +# On systems which support dynamic loading of shared libraries, Exim can
  18 +# load a local_scan function specified in its config file instead of having
  19 +# to be recompiled with the desired local_scan function. For a full
  20 +# description of the API to this function, see the Exim specification.
  21 +
  22 +DLOPEN_LOCAL_SCAN=yes
  23 +
  24 +# If you set DLOPEN_LOCAL_SCAN, then you need to include -rdynamic in the
  25 +# linker flags.  Without it, the loaded .so won't be able to access any
  26 +# functions from exim.
  27 +
  28 +LDFLAGS += -rdynamic
  29 +CFLAGS += -fvisibility=hidden
  30 +
  31 +#------------------------------------------------------------------------------
  32  # The default distribution of Exim contains only the plain text form of the
  33  # documentation. Other forms are available separately. If you want to install
  34  # the documentation in "info" format, first fetch the Texinfo documentation
  35 --- a/src/config.h.defaults
  36 +++ b/src/config.h.defaults
  37 @@ -32,6 +32,8 @@ Do not put spaces between # and the 'def
  38
  39  #define AUTH_VARS                     3
  40
  41 +#define DLOPEN_LOCAL_SCAN
  42 +
  43  #define BIN_DIRECTORY
  44
  45  #define CONFIGURE_FILE
  46 --- a/src/globals.c
  47 +++ b/src/globals.c
  48 @@ -141,6 +141,10 @@ int     dsn_ret                = 0;
  49  const pcre  *regex_DSN         = NULL;
  50  uschar *dsn_advertise_hosts    = NULL;
  51
  52 +#ifdef DLOPEN_LOCAL_SCAN
  53 +uschar *local_scan_path        = NULL;
  54 +#endif
  55 +
  56  #ifdef SUPPORT_TLS
  57  BOOL    gnutls_compat_mode     = FALSE;
  58  BOOL    gnutls_allow_auto_pkcs11 = FALSE;
  59 --- a/src/globals.h
  60 +++ b/src/globals.h
  61 @@ -138,6 +138,9 @@ extern int      dsn_ret;               /
  62  extern const pcre  *regex_DSN;         /* For recognizing DSN settings */
  63  extern uschar  *dsn_advertise_hosts;   /* host for which TLS is advertised */
  64
  65 +#ifdef DLOPEN_LOCAL_SCAN
  66 +extern uschar *local_scan_path;        /* Path to local_scan() library */
  67 +#endif
  68  /* Input-reading functions for messages, so we can use special ones for
  69  incoming TCP/IP. */
  70
  71 --- a/src/local_scan.c
  72 +++ b/src/local_scan.c
  73 @@ -5,61 +5,131 @@
  74  /* Copyright (c) University of Cambridge 1995 - 2009 */
  75  /* See the file NOTICE for conditions of use and distribution. */
  76
  77 +#include "exim.h"
  78
  79 -/******************************************************************************
  80 -This file contains a template local_scan() function that just returns ACCEPT.
  81 -If you want to implement your own version, you should copy this file to, say
  82 -Local/local_scan.c, and edit the copy. To use your version instead of the
  83 -default, you must set
  84 -
  85 -HAVE_LOCAL_SCAN=yes
  86 -LOCAL_SCAN_SOURCE=Local/local_scan.c
  87 -
  88 -in your Local/Makefile. This makes it easy to copy your version for use with
  89 -subsequent Exim releases.
  90 -
  91 -For a full description of the API to this function, see the Exim specification.
  92 -******************************************************************************/
  93 -
  94 -
  95 -/* This is the only Exim header that you should include. The effect of
  96 -including any other Exim header is not defined, and may change from release to
  97 -release. Use only the documented interface! */
  98 -
  99 -#include "local_scan.h"
 100 -
 101 -
 102 -/* This is a "do-nothing" version of a local_scan() function. The arguments
 103 -are:
 104 -
 105 -  fd             The file descriptor of the open -D file, which contains the
 106 -                   body of the message. The file is open for reading and
 107 -                   writing, but modifying it is dangerous and not recommended.
 108 -
 109 -  return_text    A pointer to an unsigned char* variable which you can set in
 110 -                   order to return a text string. It is initialized to NULL.
 111 -
 112 -The return values of this function are:
 113 -
 114 -  LOCAL_SCAN_ACCEPT
 115 -                 The message is to be accepted. The return_text argument is
 116 -                   saved in $local_scan_data.
 117 -
 118 -  LOCAL_SCAN_REJECT
 119 -                 The message is to be rejected. The returned text is used
 120 -                   in the rejection message.
 121 -
 122 -  LOCAL_SCAN_TEMPREJECT
 123 -                 This specifies a temporary rejection. The returned text
 124 -                   is used in the rejection message.
 125 -*/
 126 +#ifdef DLOPEN_LOCAL_SCAN
 127 +#include <dlfcn.h>
 128 +static int (*local_scan_fn)(int fd, uschar **return_text) = NULL;
 129 +static int load_local_scan_library(void);
 130 +#endif
 131
 132  int
 133  local_scan(int fd, uschar **return_text)
 134  {
 135  fd = fd;                      /* Keep picky compilers happy */
 136  return_text = return_text;
 137 -return LOCAL_SCAN_ACCEPT;
 138 +#ifdef DLOPEN_LOCAL_SCAN
 139 +/* local_scan_path is defined AND not the empty string */
 140 +if (local_scan_path && *local_scan_path)
 141 +  {
 142 +  if (!local_scan_fn)
 143 +    {
 144 +    if (!load_local_scan_library())
 145 +      {
 146 +        char *base_msg , *error_msg , *final_msg ;
 147 +        int final_length = -1 ;
 148 +
 149 +        base_msg=US"Local configuration error - local_scan() library failure\n";
 150 +        error_msg = dlerror() ;
 151 +
 152 +        final_length = strlen(base_msg) + strlen(error_msg) + 1 ;
 153 +        final_msg = (char*)malloc( final_length*sizeof(char) ) ;
 154 +        *final_msg = '\0' ;
 155 +
 156 +        strcat( final_msg , base_msg ) ;
 157 +        strcat( final_msg , error_msg ) ;
 158 +
 159 +        *return_text = final_msg ;
 160 +      return LOCAL_SCAN_TEMPREJECT;
 161 +      }
 162 +    }
 163 +    return local_scan_fn(fd, return_text);
 164 +  }
 165 +else
 166 +#endif
 167 +  return LOCAL_SCAN_ACCEPT;
 168 +}
 169 +
 170 +#ifdef DLOPEN_LOCAL_SCAN
 171 +
 172 +static int load_local_scan_library(void)
 173 +{
 174 +/* No point in keeping local_scan_lib since we'll never dlclose() anyway */
 175 +void *local_scan_lib = NULL;
 176 +int (*local_scan_version_fn)(void);
 177 +int vers_maj;
 178 +int vers_min;
 179 +
 180 +local_scan_lib = dlopen(local_scan_path, RTLD_NOW);
 181 +if (!local_scan_lib)
 182 +  {
 183 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library open failed - "
 184 +    "message temporarily rejected");
 185 +  return FALSE;
 186 +  }
 187 +
 188 +local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_major");
 189 +if (!local_scan_version_fn)
 190 +  {
 191 +  dlclose(local_scan_lib);
 192 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
 193 +    "local_scan_version_major() function - message temporarily rejected");
 194 +  return FALSE;
 195 +  }
 196 +
 197 +/* The major number is increased when the ABI is changed in a non
 198 +   backward compatible way. */
 199 +vers_maj = local_scan_version_fn();
 200 +
 201 +local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_minor");
 202 +if (!local_scan_version_fn)
 203 +  {
 204 +  dlclose(local_scan_lib);
 205 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
 206 +    "local_scan_version_minor() function - message temporarily rejected");
 207 +  return FALSE;
 208 +  }
 209 +
 210 +/* The minor number is increased each time a new feature is added (in a
 211 +   way that doesn't break backward compatibility) -- Marc */
 212 +vers_min = local_scan_version_fn();
 213 +
 214 +
 215 +if (vers_maj != LOCAL_SCAN_ABI_VERSION_MAJOR)
 216 +  {
 217 +  dlclose(local_scan_lib);
 218 +  local_scan_lib = NULL;
 219 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible major"
 220 +    "version number, you need to recompile your module for this version"
 221 +    "of exim (The module was compiled for version %d.%d and this exim provides"
 222 +    "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
 223 +    LOCAL_SCAN_ABI_VERSION_MINOR);
 224 +  return FALSE;
 225 +  }
 226 +else if (vers_min > LOCAL_SCAN_ABI_VERSION_MINOR)
 227 +  {
 228 +  dlclose(local_scan_lib);
 229 +  local_scan_lib = NULL;
 230 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible minor"
 231 +    "version number, you need to recompile your module for this version"
 232 +    "of exim (The module was compiled for version %d.%d and this exim provides"
 233 +    "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
 234 +    LOCAL_SCAN_ABI_VERSION_MINOR);
 235 +  return FALSE;
 236 +  }
 237 +
 238 +local_scan_fn = dlsym(local_scan_lib, "local_scan");
 239 +if (!local_scan_fn)
 240 +  {
 241 +  dlclose(local_scan_lib);
 242 +  log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
 243 +    "local_scan() function - message temporarily rejected");
 244 +  return FALSE;
 245 +  }
 246 +
 247 +return TRUE;
 248  }
 249
 250 +#endif /* DLOPEN_LOCAL_SCAN */
 251 +
 252  /* End of local_scan.c */
 253 --- a/src/local_scan.h
 254 +++ b/src/local_scan.h
 255 @@ -17,6 +17,7 @@ settings, and the store functions. */
 256
 257  #include <stdarg.h>
 258  #include <sys/types.h>
 259 +#pragma GCC visibility push(default)
 260  #include "config.h"
 261  #include "mytypes.h"
 262  #include "store.h"
 263 @@ -192,4 +193,6 @@ extern uschar *string_copy(const uschar
 264  extern uschar *string_copyn(const uschar *, int);
 265  extern uschar *string_sprintf(const char *, ...) ALMOST_PRINTF(1,2);
 266
 267 +#pragma GCC visibility pop
 268 +
 269  /* End of local_scan.h */
 270 --- a/src/readconf.c
 271 +++ b/src/readconf.c
 272 @@ -199,6 +199,9 @@ static optionlist optionlist_config[] =
 273    { "local_from_prefix",        opt_stringptr,   &local_from_prefix },
 274    { "local_from_suffix",        opt_stringptr,   &local_from_suffix },
 275    { "local_interfaces",         opt_stringptr,   &local_interfaces },
 276 +#ifdef DLOPEN_LOCAL_SCAN
 277 +  { "local_scan_path",          opt_stringptr,   &local_scan_path },
 278 +#endif
 279  #ifdef HAVE_LOCAL_SCAN
 280    { "local_scan_timeout",       opt_time,        &local_scan_timeout },
 281  #endif