+/*************************************************
+* Validate that the macros given are okay *
+*************************************************/
+
+/* Typically, Exim will drop privileges if macros are supplied. In some
+cases, we want to not do so.
+
+Arguments: none (macros is a global)
+Returns: true if trusted, false otherwise
+*/
+
+static BOOL
+macros_trusted(void)
+{
+#ifdef WHITELIST_D_MACROS
+macro_item *m;
+uschar *whitelisted, *end, *p, **whites, **w;
+int white_count, i, n;
+size_t len;
+BOOL prev_char_item, found;
+#endif
+
+if (macros == NULL)
+ return TRUE;
+#ifndef WHITELIST_D_MACROS
+return FALSE;
+#else
+
+/* We only trust -D overrides for some invoking users:
+root, the exim run-time user, the optional config owner user.
+I don't know why config-owner would be needed, but since they can own the
+config files anyway, there's no security risk to letting them override -D. */
+if ( ! ((real_uid == root_uid)
+ || (real_uid == exim_uid)
+#ifdef CONFIGURE_OWNER
+ || (real_uid == config_uid)
+#endif
+ ))
+ {
+ debug_printf("macros_trusted rejecting macros for uid %d\n", (int) real_uid);
+ return FALSE;
+ }
+
+/* Get a list of macros which are whitelisted */
+whitelisted = string_copy_malloc(US WHITELIST_D_MACROS);
+prev_char_item = FALSE;
+white_count = 0;
+for (p = whitelisted; *p != '\0'; ++p)
+ {
+ if (*p == ':' || isspace(*p))
+ {
+ *p = '\0';
+ if (prev_char_item)
+ ++white_count;
+ prev_char_item = FALSE;
+ continue;
+ }
+ if (!prev_char_item)
+ prev_char_item = TRUE;
+ }
+end = p;
+if (prev_char_item)
+ ++white_count;
+if (!white_count)
+ return FALSE;
+whites = store_malloc(sizeof(uschar *) * (white_count+1));
+for (p = whitelisted, i = 0; (p != end) && (i < white_count); ++p)
+ {
+ if (*p != '\0')
+ {
+ whites[i++] = p;
+ if (i == white_count)
+ break;
+ while (*p != '\0' && p < end)
+ ++p;
+ }
+ }
+whites[i] = NULL;
+
+/* The list of macros should be very short. Accept the N*M complexity. */
+for (m = macros; m != NULL; m = m->next)
+ {
+ found = FALSE;
+ for (w = whites; *w; ++w)
+ if (Ustrcmp(*w, m->name) == 0)
+ {
+ found = TRUE;
+ break;
+ }
+ if (!found)
+ return FALSE;
+ if (m->replacement == NULL)
+ continue;
+ len = Ustrlen(m->replacement);
+ if (len == 0)
+ continue;
+ n = pcre_exec(regex_whitelisted_macro, NULL, CS m->replacement, len,
+ 0, PCRE_EOPT, NULL, 0);
+ if (n < 0)
+ {
+ if (n != PCRE_ERROR_NOMATCH)
+ debug_printf("macros_trusted checking %s returned %d\n", m->name, n);
+ return FALSE;
+ }
+ }
+debug_printf("macros_trusted overriden to true by whitelisting\n");
+return TRUE;
+#endif
+}
+
+
git://git.exim.org / exim.git / blobdiff