DNS: more hardening against crafted responses

[exim.git] / src / src / acl.c

diff --git a/src/src/acl.c b/src/src/acl.c
index a1694fcdde2e64524fa8aad97644a8b725dc1453..302dedaeb21fdde5f982fd5613701b04810a13f2 100644 (file)
--- a/src/src/acl.c
+++ b/src/src/acl.c
@@ -5,6 +5,7 @@
 /* Copyright (c) The Exim Maintainers 2020 - 2022 */
 /* Copyright (c) University of Cambridge 1995 - 2018 */
 /* See the file NOTICE for conditions of use and distribution. */
 /* Copyright (c) The Exim Maintainers 2020 - 2022 */
 /* Copyright (c) University of Cambridge 1995 - 2018 */
 /* See the file NOTICE for conditions of use and distribution. */

+/* SPDX-License-Identifier: GPL-2.0-or-later */

 
 /* Code for handling Access Control Lists (ACLs) */
 
 
 /* Code for handling Access Control Lists (ACLs) */
 


@@ -222,7 +223,7 @@ static condition_def conditions[] = {
   },
   [ACLC_ENCRYPTED] =           { US"encrypted",        FALSE, FALSE,
                                  ACL_BIT_NOTSMTP | ACL_BIT_NOTSMTP_START |
   },
   [ACLC_ENCRYPTED] =           { US"encrypted",        FALSE, FALSE,
                                  ACL_BIT_NOTSMTP | ACL_BIT_NOTSMTP_START |

-                                   ACL_BIT_HELO,
+                                   ACL_BIT_CONNECT

   },
 
   [ACLC_ENDPASS] =             { US"endpass",  TRUE, TRUE,     0 },
   },
 
   [ACLC_ENDPASS] =             { US"endpass",  TRUE, TRUE,     0 },


@@ -734,6 +735,78 @@ return -1;
 }
 
 
 }
 
 

+static BOOL
+acl_varname_to_cond(const uschar ** sp, acl_condition_block * cond, uschar ** error)
+{
+const uschar * s = *sp, * endptr;
+
+#ifndef DISABLE_DKIM
+if (  Ustrncmp(s, "dkim_verify_status", 18) == 0
+   || Ustrncmp(s, "dkim_verify_reason", 18) == 0)
+  {
+  endptr = s+18;
+  if (isalnum(*endptr))
+    {
+    *error = string_sprintf("invalid variable name after \"set\" in ACL "
+      "modifier \"set %s\" "
+      "(only \"dkim_verify_status\" or \"dkim_verify_reason\" permitted)",
+      s);
+    return FALSE;
+    }
+  cond->u.varname = string_copyn(s, 18);
+  }
+else
+#endif
+  {
+  if (Ustrncmp(s, "acl_c", 5) != 0 && Ustrncmp(s, "acl_m", 5) != 0)
+    {
+    *error = string_sprintf("invalid variable name after \"set\" in ACL "
+      "modifier \"set %s\" (must start \"acl_c\" or \"acl_m\")", s);
+    return FALSE;
+    }
+
+  endptr = s + 5;
+  if (!isdigit(*endptr) && *endptr != '_')
+    {
+    *error = string_sprintf("invalid variable name after \"set\" in ACL "
+      "modifier \"set %s\" (digit or underscore must follow acl_c or acl_m)",
+      s);
+    return FALSE;
+    }
+
+  for ( ; *endptr && *endptr != '=' && !isspace(*endptr); endptr++)
+    if (!isalnum(*endptr) && *endptr != '_')
+      {
+      *error = string_sprintf("invalid character \"%c\" in variable name "
+       "in ACL modifier \"set %s\"", *endptr, s);
+      return FALSE;
+      }
+
+  cond->u.varname = string_copyn(s + 4, endptr - s - 4);
+  }
+s = endptr;
+Uskip_whitespace(&s);
+*sp = s;
+return TRUE;
+}
+
+
+static BOOL
+acl_data_to_cond(const uschar * s, acl_condition_block * cond,
+  const uschar * name, uschar ** error)
+{
+if (*s++ != '=')
+  {
+  *error = string_sprintf("\"=\" missing after ACL \"%s\" %s", name,
+    conditions[cond->type].is_modifier ? US"modifier" : US"condition");
+  return FALSE;;
+  }
+Uskip_whitespace(&s);
+cond->arg = string_copy(s);
+return TRUE;
+}
+
+

 /*************************************************
 *            Read and parse one ACL              *
 *************************************************/
 /*************************************************
 *            Read and parse one ACL              *
 *************************************************/


@@ -760,7 +833,7 @@ acl_block **lastp = &yield;
 acl_block *this = NULL;
 acl_condition_block *cond;
 acl_condition_block **condp = NULL;
 acl_block *this = NULL;
 acl_condition_block *cond;
 acl_condition_block **condp = NULL;

-uschar * s;
+const uschar * s;

 
 *error = NULL;
 
 
 *error = NULL;
 


@@ -768,7 +841,7 @@ while ((s = (*func)()))
   {
   int v, c;
   BOOL negated = FALSE;
   {
   int v, c;
   BOOL negated = FALSE;

-  uschar *saveline = s;
+  const uschar * saveline = s;

   uschar name[EXIM_DRIVERNAME_MAX];
 
   /* Conditions (but not verbs) are allowed to be negated by an initial
   uschar name[EXIM_DRIVERNAME_MAX];
 
   /* Conditions (but not verbs) are allowed to be negated by an initial


@@ -808,16 +881,15 @@ while ((s = (*func)()))
       *error = string_sprintf("malformed ACL line \"%s\"", saveline);
       return NULL;
       }
       *error = string_sprintf("malformed ACL line \"%s\"", saveline);
       return NULL;
       }

-    this = store_get(sizeof(acl_block), GET_UNTAINTED);
-    *lastp = this;
-    lastp = &(this->next);
+    *lastp = this = store_get(sizeof(acl_block), GET_UNTAINTED);
+    lastp = &this->next;

     this->next = NULL;
     this->condition = NULL;
     this->verb = v;
     this->srcline = config_lineno;     /* for debug output */
     this->srcfile = config_filename;   /**/
     this->next = NULL;
     this->condition = NULL;
     this->verb = v;
     this->srcline = config_lineno;     /* for debug output */
     this->srcfile = config_filename;   /**/

-    condp = &(this->condition);
-    if (*s == 0) continue;               /* No condition on this line */
+    condp = &this->condition;
+    if (!*s) continue;               /* No condition on this line */

     if (*s == '!')
       {
       negated = TRUE;
     if (*s == '!')
       {
       negated = TRUE;


@@ -861,7 +933,7 @@ while ((s = (*func)()))
   cond->u.negated = negated;
 
   *condp = cond;
   cond->u.negated = negated;
 
   *condp = cond;

-  condp = &(cond->next);
+  condp = &cond->next;

 
   /* The "set" modifier is different in that its argument is "name=value"
   rather than just a value, and we can check the validity of the name, which
 
   /* The "set" modifier is different in that its argument is "name=value"
   rather than just a value, and we can check the validity of the name, which


@@ -874,75 +946,13 @@ while ((s = (*func)()))
   compatibility. */
 
   if (c == ACLC_SET)
   compatibility. */
 
   if (c == ACLC_SET)

-#ifndef DISABLE_DKIM
-    if (  Ustrncmp(s, "dkim_verify_status", 18) == 0
-       || Ustrncmp(s, "dkim_verify_reason", 18) == 0)
-      {
-      uschar * endptr = s+18;
-
-      if (isalnum(*endptr))
-       {
-       *error = string_sprintf("invalid variable name after \"set\" in ACL "
-         "modifier \"set %s\" "
-         "(only \"dkim_verify_status\" or \"dkim_verify_reason\" permitted)",
-         s);
-       return NULL;
-       }
-      cond->u.varname = string_copyn(s, 18);
-      s = endptr;
-      Uskip_whitespace(&s);
-      }
-    else
-#endif
-    {
-    uschar *endptr;
-
-    if (Ustrncmp(s, "acl_c", 5) != 0 && Ustrncmp(s, "acl_m", 5) != 0)
-      {
-      *error = string_sprintf("invalid variable name after \"set\" in ACL "
-       "modifier \"set %s\" (must start \"acl_c\" or \"acl_m\")", s);
-      return NULL;
-      }
-
-    endptr = s + 5;
-    if (!isdigit(*endptr) && *endptr != '_')
-      {
-      *error = string_sprintf("invalid variable name after \"set\" in ACL "
-       "modifier \"set %s\" (digit or underscore must follow acl_c or acl_m)",
-       s);
-      return NULL;
-      }
-
-    while (*endptr && *endptr != '=' && !isspace(*endptr))
-      {
-      if (!isalnum(*endptr) && *endptr != '_')
-       {
-       *error = string_sprintf("invalid character \"%c\" in variable name "
-         "in ACL modifier \"set %s\"", *endptr, s);
-       return NULL;
-       }
-      endptr++;
-      }
-
-    cond->u.varname = string_copyn(s + 4, endptr - s - 4);
-    s = endptr;
-    Uskip_whitespace(&s);
-    }
+    if (!acl_varname_to_cond(&s, cond, error)) return NULL;

 
   /* For "set", we are now positioned for the data. For the others, only
   "endpass" has no data */
 
   if (c != ACLC_ENDPASS)
 
   /* For "set", we are now positioned for the data. For the others, only
   "endpass" has no data */
 
   if (c != ACLC_ENDPASS)

-    {
-    if (*s++ != '=')
-      {
-      *error = string_sprintf("\"=\" missing after ACL \"%s\" %s", name,
-        conditions[c].is_modifier ? US"modifier" : US"condition");
-      return NULL;
-      }
-    Uskip_whitespace(&s);
-    cond->arg = string_copy(s);
-    }
+    if (!acl_data_to_cond(s, cond, name, error)) return NULL;

   }
 
 return yield;
   }
 
 return yield;


@@ -1082,7 +1092,7 @@ for (header_line * h = acl_added_headers; h; h = h->next)
   g = string_append_listele_n(g, '\n', h->text, i);
   }
 
   g = string_append_listele_n(g, '\n', h->text, i);
   }
 

-return g ? g->s : NULL;
+return string_from_gstring(g);

 }
 
 
 }
 
 


@@ -1424,6 +1434,7 @@ for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
 
   /* Extract the numerical SRV fields (p is incremented) */
 
 
   /* Extract the numerical SRV fields (p is incremented) */
 

+  if (rr_bad_size(rr, 3 * sizeof(uint16_t))) continue;

   GETSHORT(priority, p);
   GETSHORT(weight, p);
   GETSHORT(port, p);
   GETSHORT(priority, p);
   GETSHORT(weight, p);
   GETSHORT(port, p);


@@ -1633,6 +1644,30 @@ return period;
 
 
 
 
 
 

+static BOOL
+sender_helo_verified_internal(void)
+{
+/* We can test the result of optional HELO verification that might have
+occurred earlier. If not, we can attempt the verification now. */
+
+if (!f.helo_verified && !f.helo_verify_failed) smtp_verify_helo();
+return f.helo_verified;
+}
+
+static int
+sender_helo_verified_cond(void)
+{
+return sender_helo_verified_internal() ? OK : FAIL;
+}
+
+uschar *
+sender_helo_verified_boolstr(void)
+{
+return sender_helo_verified_internal() ? US"yes" : US"no";
+}
+
+
+

 /* This function implements the "verify" condition. It is called when
 encountered in any ACL, because some tests are almost always permitted. Some
 just don't make sense, and always fail (for example, an attempt to test a host
 /* This function implements the "verify" condition. It is called when
 encountered in any ACL, because some tests are almost always permitted. Some
 just don't make sense, and always fail (for example, an attempt to test a host


@@ -1729,11 +1764,7 @@ switch(vp->value)
     return FAIL;
 
   case VERIFY_HELO:
     return FAIL;
 
   case VERIFY_HELO:

-    /* We can test the result of optional HELO verification that might have
-    occurred earlier. If not, we can attempt the verification now. */
-
-    if (!f.helo_verified && !f.helo_verify_failed) smtp_verify_helo();
-    return f.helo_verified ? OK : FAIL;
+    return sender_helo_verified_cond();

 
   case VERIFY_CSA:
     /* Do Client SMTP Authorization checks in a separate function, and turn the
 
   case VERIFY_CSA:
     /* Do Client SMTP Authorization checks in a separate function, and turn the


@@ -2520,6 +2551,7 @@ else switch(mode)
     anchor = NULL; /* silence an "unused" complaint */
     log_write(0, LOG_MAIN|LOG_PANIC_DIE,
       "internal ACL error: unknown ratelimit mode %d", mode);
     anchor = NULL; /* silence an "unused" complaint */
     log_write(0, LOG_MAIN|LOG_PANIC_DIE,
       "internal ACL error: unknown ratelimit mode %d", mode);

+    /*NOTREACHED*/

     break;
   }
 
     break;
   }
 


@@ -3116,17 +3148,15 @@ acl_check_condition(int verb, acl_condition_block *cb, int where,
   address_item *addr, int level, BOOL *epp, uschar **user_msgptr,
   uschar **log_msgptr, int *basic_errno)
 {
   address_item *addr, int level, BOOL *epp, uschar **user_msgptr,
   uschar **log_msgptr, int *basic_errno)
 {

-uschar *user_message = NULL;
-uschar *log_message = NULL;
+uschar * user_message = NULL;
+uschar * log_message = NULL;

 int rc = OK;
 int rc = OK;

-#ifdef WITH_CONTENT_SCAN
-int sep = -'/';
-#endif

 
 for (; cb; cb = cb->next)
   {
 
 for (; cb; cb = cb->next)
   {

-  const uschar *arg;
+  const uschar * arg;

   int control_type;
   int control_type;

+  BOOL textonly = FALSE;

 
   /* The message and log_message items set up messages to be used in
   case of rejection. They are expanded later. */
 
   /* The message and log_message items set up messages to be used in
   case of rejection. They are expanded later. */


@@ -3160,7 +3190,8 @@ for (; cb; cb = cb->next)
 
   if (!conditions[cb->type].expand_at_top)
     arg = cb->arg;
 
   if (!conditions[cb->type].expand_at_top)
     arg = cb->arg;

-  else if (!(arg = expand_string(cb->arg)))
+
+  else if (!(arg = expand_string_2(cb->arg, &textonly)))

     {
     if (f.expand_string_forcedfail) continue;
     *log_msgptr = string_sprintf("failed to expand ACL string \"%s\": %s",
     {
     if (f.expand_string_forcedfail) continue;
     *log_msgptr = string_sprintf("failed to expand ACL string \"%s\": %s",


@@ -3398,7 +3429,7 @@ for (; cb; cb = cb->next)
        case CONTROL_FAKEREJECT:
          cancel_cutthrough_connection(TRUE, US"fakereject");
        case CONTROL_FAKEDEFER:
        case CONTROL_FAKEREJECT:
          cancel_cutthrough_connection(TRUE, US"fakereject");
        case CONTROL_FAKEDEFER:

-         fake_response = (control_type == CONTROL_FAKEDEFER) ? DEFER : FAIL;
+         fake_response = control_type == CONTROL_FAKEDEFER ? DEFER : FAIL;

          if (*p == '/')
            {
            const uschar *pp = p + 1;
          if (*p == '/')
            {
            const uschar *pp = p + 1;


@@ -3635,12 +3666,13 @@ for (; cb; cb = cb->next)
       break;
       }
 
       break;
       }
 

-    #ifdef EXPERIMENTAL_DCC
+#ifdef EXPERIMENTAL_DCC

     case ACLC_DCC:
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;
     case ACLC_DCC:
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;

-      uschar *ss = string_nextinlist(&list, &sep, NULL, 0);
+      int sep = -'/';
+      uschar * ss = string_nextinlist(&list, &sep, NULL, 0);

       /* Run the dcc backend. */
       rc = dcc_process(&ss);
       /* Modify return code based upon the existence of options. */
       /* Run the dcc backend. */
       rc = dcc_process(&ss);
       /* Modify return code based upon the existence of options. */


@@ -3649,13 +3681,13 @@ for (; cb; cb = cb->next)
           rc = FAIL;   /* FAIL so that the message is passed to the next ACL */
       break;
       }
           rc = FAIL;   /* FAIL so that the message is passed to the next ACL */
       break;
       }

-    #endif
+#endif

 
 

-    #ifdef WITH_CONTENT_SCAN
+#ifdef WITH_CONTENT_SCAN

     case ACLC_DECODE:
       rc = mime_decode(&arg);
       break;
     case ACLC_DECODE:
       rc = mime_decode(&arg);
       break;

-    #endif
+#endif

 
     case ACLC_DELAY:
       {
 
     case ACLC_DELAY:
       {


@@ -3742,8 +3774,9 @@ for (; cb; cb = cb->next)
       if (!f.dmarc_has_been_checked)
        dmarc_process();
       f.dmarc_has_been_checked = TRUE;
       if (!f.dmarc_has_been_checked)
        dmarc_process();
       f.dmarc_has_been_checked = TRUE;

+

       /* used long way of dmarc_exim_expand_query() in case we need more
       /* used long way of dmarc_exim_expand_query() in case we need more

-       * view into the process in the future. */
+      view into the process in the future. */

       rc = match_isinlist(dmarc_exim_expand_query(DMARC_VERIFY_STATUS),
                          &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL);
       break;
       rc = match_isinlist(dmarc_exim_expand_query(DMARC_VERIFY_STATUS),
                          &arg, 0, NULL, NULL, MCL_STRING, TRUE, NULL);
       break;


@@ -3802,11 +3835,10 @@ for (; cb; cb = cb->next)
 
     case ACLC_LOG_REJECT_TARGET:
       {
 
     case ACLC_LOG_REJECT_TARGET:
       {

-      int logbits = 0;
-      int sep = 0;
-      const uschar *s = arg;
-      uschar * ss;
-      while ((ss = string_nextinlist(&s, &sep, NULL, 0)))
+      int logbits = 0, sep = 0;
+      const uschar * s = arg;
+
+      for (uschar * ss; ss = string_nextinlist(&s, &sep, NULL, 0); )

         {
         if (Ustrcmp(ss, "main") == 0) logbits |= LOG_MAIN;
         else if (Ustrcmp(ss, "panic") == 0) logbits |= LOG_PANIC;
         {
         if (Ustrcmp(ss, "main") == 0) logbits |= LOG_MAIN;
         else if (Ustrcmp(ss, "panic") == 0) logbits |= LOG_PANIC;


@@ -3854,17 +3886,16 @@ for (; cb; cb = cb->next)
       break;
       }
 
       break;
       }
 

-    #ifdef WITH_CONTENT_SCAN
+#ifdef WITH_CONTENT_SCAN

     case ACLC_MALWARE:                 /* Run the malware backend. */
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;
     case ACLC_MALWARE:                 /* Run the malware backend. */
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;

-      uschar * ss = string_nextinlist(&list, &sep, NULL, 0);
-      uschar * opt;

       BOOL defer_ok = FALSE;
       BOOL defer_ok = FALSE;

-      int timeout = 0;
+      int timeout = 0, sep = -'/';
+      uschar * ss = string_nextinlist(&list, &sep, NULL, 0);

 
 

-      while ((opt = string_nextinlist(&list, &sep, NULL, 0)))
+      for (uschar * opt; opt = string_nextinlist(&list, &sep, NULL, 0); )

         if (strcmpic(opt, US"defer_ok") == 0)
          defer_ok = TRUE;
        else if (  strncmpic(opt, US"tmo=", 4) == 0
         if (strcmpic(opt, US"defer_ok") == 0)
          defer_ok = TRUE;
        else if (  strncmpic(opt, US"tmo=", 4) == 0


@@ -3875,16 +3906,16 @@ for (; cb; cb = cb->next)
          return ERROR;
          }
 
          return ERROR;
          }
 

-      rc = malware(ss, timeout);
+      rc = malware(ss, textonly, timeout);

       if (rc == DEFER && defer_ok)
        rc = FAIL;      /* FAIL so that the message is passed to the next ACL */
       break;
       }
 
     case ACLC_MIME_REGEX:
       if (rc == DEFER && defer_ok)
        rc = FAIL;      /* FAIL so that the message is passed to the next ACL */
       break;
       }
 
     case ACLC_MIME_REGEX:

-      rc = mime_regex(&arg);
+      rc = mime_regex(&arg, textonly);

       break;
       break;

-    #endif
+#endif

 
     case ACLC_QUEUE:
       if (is_tainted(arg))
 
     case ACLC_QUEUE:
       if (is_tainted(arg))


@@ -3913,7 +3944,7 @@ for (; cb; cb = cb->next)
 
     #ifdef WITH_CONTENT_SCAN
     case ACLC_REGEX:
 
     #ifdef WITH_CONTENT_SCAN
     case ACLC_REGEX:

-      rc = regex(&arg);
+      rc = regex(&arg, textonly);

       break;
     #endif
 
       break;
     #endif
 


@@ -3968,7 +3999,8 @@ for (; cb; cb = cb->next)
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;
       {
       /* Separate the regular expression and any optional parameters. */
       const uschar * list = arg;

-      uschar *ss = string_nextinlist(&list, &sep, NULL, 0);
+      int sep = -'/';
+      uschar * ss = string_nextinlist(&list, &sep, NULL, 0);

 
       rc = spam(CUSS &ss);
       /* Modify return code based upon the existence of options. */
 
       rc = spam(CUSS &ss);
       /* Modify return code based upon the existence of options. */


@@ -4892,6 +4924,29 @@ if (is_tainted(value))
 fprintf(f, "acl%c %s %d\n%s\n", name[0], name+1, Ustrlen(value), value);
 }
 
 fprintf(f, "acl%c %s %d\n%s\n", name[0], name+1, Ustrlen(value), value);
 }
 

+
+
+
+uschar *
+acl_standalone_setvar(const uschar * s)
+{
+acl_condition_block * cond = store_get(sizeof(acl_condition_block), GET_UNTAINTED);
+uschar * errstr = NULL, * log_msg = NULL;
+BOOL endpass_seen;
+int e;
+
+cond->next = NULL;
+cond->type = ACLC_SET;
+if (!acl_varname_to_cond(&s, cond, &errstr)) return errstr;
+if (!acl_data_to_cond(s, cond, US"'-be'", &errstr)) return errstr;
+
+if (acl_check_condition(ACL_WARN, cond, ACL_WHERE_UNKNOWN,
+                           NULL, 0, &endpass_seen, &errstr, &log_msg, &e) != OK)
+  return string_sprintf("oops: %s", errstr);
+return string_sprintf("variable %s set", cond->u.varname);
+}
+
+

 #endif /* !MACRO_PREDEF */
 /* vi: aw ai sw=2
 */
 #endif /* !MACRO_PREDEF */
 /* vi: aw ai sw=2
 */