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