X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/c2a1bba0d1fe5e19f93c92544422036814695c45..56a6b0606bb11f53653e9d208f81ffffc4b1d5a6:/src/src/rda.c

diff --git a/src/src/rda.c b/src/src/rda.c
index 4131ac612..9c2aa5022 100644
--- a/src/src/rda.c
+++ b/src/src/rda.c
@@ -2,8 +2,10 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
+/* 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 */
 
 /* This module contains code for extracting addresses from a forwarding list
 (from an alias or forward file) or by running the filter interpreter. It may do
@@ -41,15 +43,15 @@ Returns:   FILTER_EXIM    if it starts with "# Exim filter"
 static BOOL
 match_tag(const uschar *s, const uschar *tag)
 {
-for (; *tag != 0; s++, tag++)
-  {
+for (; *tag; s++, tag++)
   if (*tag == ' ')
     {
     while (*s == ' ' || *s == '\t') s++;
     s--;
     }
-  else if (tolower(*s) != tolower(*tag)) break;
-  }
+  else
+   if (tolower(*s) != tolower(*tag)) break;
+
 return (*tag == 0);
 }
 
@@ -59,10 +61,10 @@ tags for other types of filter. */
 int
 rda_is_filter(const uschar *s)
 {
-while (isspace(*s)) s++;     /* Skips initial blank lines */
-if (match_tag(s, CUS"# exim filter")) return FILTER_EXIM;
-  else if (match_tag(s, CUS"# sieve filter")) return FILTER_SIEVE;
-    else return FILTER_FORWARD;
+Uskip_whitespace(&s);			/* Skips initial blank lines */
+if (match_tag(s, CUS"# exim filter"))		return FILTER_EXIM;
+else if (match_tag(s, CUS"# sieve filter"))	return FILTER_SIEVE;
+else						return FILTER_FORWARD;
 }
 
 
@@ -96,37 +98,37 @@ static int
 rda_exists(uschar *filename, uschar **error)
 {
 int rc, saved_errno;
-uschar *slash;
 struct stat statbuf;
+uschar * s;
 
 if ((rc = Ustat(filename, &statbuf)) >= 0) return FILE_EXIST;
 saved_errno = errno;
 
-Ustrncpy(big_buffer, filename, big_buffer_size - 3);
+s = string_copy(filename);
 sigalrm_seen = FALSE;
 
 if (saved_errno == ENOENT)
   {
-  slash = Ustrrchr(big_buffer, '/');
-  Ustrcpy(slash+1, ".");
+  uschar * slash = Ustrrchr(s, '/');
+  Ustrcpy(slash+1, US".");
 
   ALARM(30);
-  rc = Ustat(big_buffer, &statbuf);
+  rc = Ustat(s, &statbuf);
   if (rc != 0 && errno == EACCES && !sigalrm_seen)
     {
     *slash = 0;
-    rc = Ustat(big_buffer, &statbuf);
+    rc = Ustat(s, &statbuf);
     }
   saved_errno = errno;
   ALARM_CLR(0);
 
-  DEBUG(D_route) debug_printf("stat(%s)=%d\n", big_buffer, rc);
+  DEBUG(D_route) debug_printf("stat(%s)=%d\n", s, rc);
   }
 
 if (sigalrm_seen || rc != 0)
   {
-  *error = string_sprintf("failed to stat %s (%s)", big_buffer,
-    sigalrm_seen? "timeout" : strerror(saved_errno));
+  *error = string_sprintf("failed to stat %s (%s)", s,
+    sigalrm_seen?  "timeout" : strerror(saved_errno));
   return FILE_EXIST_UNCLEAR;
   }
 
@@ -165,7 +167,7 @@ Returns:      pointer to string in store; NULL on error
 */
 
 static uschar *
-rda_get_file_contents(redirect_block *rdata, int options, uschar **error,
+rda_get_file_contents(const redirect_block *rdata, int options, uschar **error,
   int *yield)
 {
 FILE *fwd;
@@ -175,6 +177,17 @@ BOOL uid_ok = !rdata->check_owner;
 BOOL gid_ok = !rdata->check_group;
 struct stat statbuf;
 
+/* Reading a file is a form of expansion; we wish to deny attackers the
+capability to specify the file name. */
+
+if (is_tainted(filename))
+  {
+  *error = string_sprintf("Tainted name '%s' for file read not permitted\n",
+			filename);
+  *yield = FF_ERROR;
+  return NULL;
+  }
+
 /* Attempt to open the file. If it appears not to exist, check up on the
 containing directory by statting it. If the directory does not exist, we treat
 this situation as an error (which will cause delivery to defer); otherwise we
@@ -184,40 +197,35 @@ However, if the ignore_enotdir option is set (to ignore "something on the
 path is not a directory" errors), the right behaviour seems to be not to do the
 directory test. */
 
-fwd = Ufopen(filename, "rb");
-if (fwd == NULL)
+if (!(fwd = Ufopen(filename, "rb"))) switch(errno)
   {
-  switch(errno)
-    {
-    case ENOENT:          /* File does not exist */
+  case ENOENT:          /* File does not exist */
     DEBUG(D_route) debug_printf("%s does not exist\n%schecking parent directory\n",
-      filename,
-      ((options & RDO_ENOTDIR) != 0)? "ignore_enotdir set => skip " : "");
-    *yield = (((options & RDO_ENOTDIR) != 0) ||
-              rda_exists(filename, error) == FILE_NOT_EXIST)?
-      FF_NONEXIST : FF_ERROR;
+      filename, options & RDO_ENOTDIR ? "ignore_enotdir set => skip " : "");
+    *yield =
+	options & RDO_ENOTDIR || rda_exists(filename, error) == FILE_NOT_EXIST
+	? FF_NONEXIST : FF_ERROR;
     return NULL;
 
-    case ENOTDIR:         /* Something on the path isn't a directory */
-    if ((options & RDO_ENOTDIR) == 0) goto DEFAULT_ERROR;
+  case ENOTDIR:         /* Something on the path isn't a directory */
+    if (!(options & RDO_ENOTDIR)) goto DEFAULT_ERROR;
     DEBUG(D_route) debug_printf("non-directory on path %s: file assumed not to "
       "exist\n", filename);
     *yield = FF_NONEXIST;
     return NULL;
 
-    case EACCES:           /* Permission denied */
-    if ((options & RDO_EACCES) == 0) goto DEFAULT_ERROR;
+  case EACCES:           /* Permission denied */
+    if (!(options & RDO_EACCES)) goto DEFAULT_ERROR;
     DEBUG(D_route) debug_printf("permission denied for %s: file assumed not to "
       "exist\n", filename);
     *yield = FF_NONEXIST;
     return NULL;
 
-    DEFAULT_ERROR:
-    default:
-    *error = string_open_failed(errno, "%s", filename);
+DEFAULT_ERROR:
+  default:
+    *error = string_open_failed("%s", filename);
     *yield = FF_ERROR;
     return NULL;
-    }
   }
 
 /* Check that we have a regular file. */
@@ -246,28 +254,18 @@ if ((statbuf.st_mode & rdata->modemask) != 0)
 /* Check the file owner and file group if required to do so. */
 
 if (!uid_ok)
-  {
-  if (rdata->pw != NULL && statbuf.st_uid == rdata->pw->pw_uid)
+  if (rdata->pw && statbuf.st_uid == rdata->pw->pw_uid)
     uid_ok = TRUE;
-  else if (rdata->owners != NULL)
-    {
-    int i;
-    for (i = 1; i <= (int)(rdata->owners[0]); i++)
+  else if (rdata->owners)
+    for (int i = 1; i <= (int)(rdata->owners[0]); i++)
       if (rdata->owners[i] == statbuf.st_uid) { uid_ok = TRUE; break; }
-    }
-  }
 
 if (!gid_ok)
-  {
-  if (rdata->pw != NULL && statbuf.st_gid == rdata->pw->pw_gid)
+  if (rdata->pw && statbuf.st_gid == rdata->pw->pw_gid)
     gid_ok = TRUE;
-  else if (rdata->owngroups != NULL)
-    {
-    int i;
-    for (i = 1; i <= (int)(rdata->owngroups[0]); i++)
+  else if (rdata->owngroups)
+    for (int i = 1; i <= (int)(rdata->owngroups[0]); i++)
       if (rdata->owngroups[i] == statbuf.st_gid) { gid_ok = TRUE; break; }
-    }
-  }
 
 if (!uid_ok || !gid_ok)
   {
@@ -287,7 +285,7 @@ if (statbuf.st_size > MAX_FILTER_SIZE)
 
 /* Read the file in one go in order to minimize the time we have it open. */
 
-filebuf = store_get(statbuf.st_size + 1);
+filebuf = store_get(statbuf.st_size + 1, filename);
 
 if (fread(filebuf, 1, statbuf.st_size, fwd) != statbuf.st_size)
   {
@@ -297,8 +295,8 @@ if (fread(filebuf, 1, statbuf.st_size, fwd) != statbuf.st_size)
   }
 filebuf[statbuf.st_size] = 0;
 
-DEBUG(D_route)
-  debug_printf(OFF_T_FMT " bytes read from %s\n", statbuf.st_size, filename);
+DEBUG(D_route) debug_printf(OFF_T_FMT " %sbytes read from %s\n",
+  statbuf.st_size, is_tainted(filename) ? "(tainted) " : "", filename);
 
 (void)fclose(fwd);
 return filebuf;
@@ -342,19 +340,19 @@ Returns:                    a suitable return for rda_interpret()
 */
 
 static int
-rda_extract(redirect_block *rdata, int options, uschar *include_directory,
-  uschar *sieve_vacation_directory, uschar *sieve_enotify_mailto_owner,
-  uschar *sieve_useraddress, uschar *sieve_subaddress,
-  address_item **generated, uschar **error, error_block **eblockp,
-  int *filtertype)
+rda_extract(const redirect_block * rdata, int options,
+  const uschar * include_directory, const uschar * sieve_vacation_directory,
+  const uschar * sieve_enotify_mailto_owner, const uschar * sieve_useraddress,
+  const uschar * sieve_subaddress, address_item ** generated, uschar ** error,
+  error_block ** eblockp, int * filtertype)
 {
-uschar *data;
+const uschar * data;
 
 if (rdata->isfile)
   {
   int yield = 0;
-  data = rda_get_file_contents(rdata, options, error, &yield);
-  if (data == NULL) return yield;
+  if (!(data = rda_get_file_contents(rdata, options, error, &yield)))
+    return yield;
   }
 else data = rdata->string;
 
@@ -372,19 +370,18 @@ if (*filtertype != FILTER_FORWARD)
   int old_expand_forbid = expand_forbid;
 
   DEBUG(D_route) debug_printf("data is %s filter program\n",
-    (*filtertype == FILTER_EXIM)? "an Exim" : "a Sieve");
+    *filtertype == FILTER_EXIM ? "an Exim" : "a Sieve");
 
   /* RDO_FILTER is an "allow" bit */
 
-  if ((options & RDO_FILTER) == 0)
+  if (!(options & RDO_FILTER))
     {
     *error = US"filtering not enabled";
     return FF_ERROR;
     }
 
   expand_forbid =
-    (expand_forbid & ~RDO_FILTER_EXPANSIONS) |
-    (options & RDO_FILTER_EXPANSIONS);
+    expand_forbid & ~RDO_FILTER_EXPANSIONS  |  options & RDO_FILTER_EXPANSIONS;
 
   /* RDO_{EXIM,SIEVE}_FILTER are forbid bits */
 
@@ -399,7 +396,7 @@ if (*filtertype != FILTER_FORWARD)
     }
   else
     {
-    if ((options & RDO_SIEVE_FILTER) != 0)
+    if (options & RDO_SIEVE_FILTER)
       {
       *error = US"Sieve filtering not enabled";
       return FF_ERROR;
@@ -446,9 +443,9 @@ Returns:     -1 on error, else 0
 static int
 rda_write_string(int fd, const uschar *s)
 {
-int len = (s == NULL)? 0 : Ustrlen(s) + 1;
+int len = s ? Ustrlen(s) + 1 : 0;
 return (  write(fd, &len, sizeof(int)) != sizeof(int)
-       || (s != NULL  &&  write(fd, s, len) != len)
+       || (s   &&  write(fd, s, len) != len)
        )
        ? -1 : 0;
 }
@@ -479,7 +476,8 @@ if (len == 0)
 else
   /* We know we have enough memory so disable the error on "len" */
   /* coverity[tainted_data] */
-  if (read(fd, *sp = store_get(len), len) != len) return FALSE;
+  /* We trust the data source, so untainted */
+  if (read(fd, *sp = store_get(len, GET_UNTAINTED), len) != len) return FALSE;
 return TRUE;
 }
 
@@ -492,7 +490,7 @@ return TRUE;
 /* This function is passed a forward list string (unexpanded) or the name of a
 file (unexpanded) whose contents are the forwarding list. The list may in fact
 be a filter program if it starts with "#Exim filter" or "#Sieve filter". Other
-types of filter, with different inital tag strings, may be introduced in due
+types of filter, with different initial tag strings, may be introduced in due
 course.
 
 The job of the function is to process the forwarding list or filter. It is
@@ -544,11 +542,11 @@ Returns:        values from extraction function, or FF_NONEXIST:
 */
 
 int
-rda_interpret(redirect_block *rdata, int options, uschar *include_directory,
-  uschar *sieve_vacation_directory, uschar *sieve_enotify_mailto_owner,
-  uschar *sieve_useraddress, uschar *sieve_subaddress, ugid_block *ugid,
-  address_item **generated, uschar **error, error_block **eblockp,
-  int *filtertype, uschar *rname)
+rda_interpret(redirect_block * rdata, int options,
+  const uschar * include_directory, const uschar * sieve_vacation_directory,
+  const uschar * sieve_enotify_mailto_owner, const uschar * sieve_useraddress,
+  const uschar * sieve_subaddress, const ugid_block * ugid, address_item ** generated,
+  uschar ** error, error_block ** eblockp, int * filtertype, const uschar * rname)
 {
 int fd, rc, pfd[2];
 int yield, status;
@@ -558,13 +556,12 @@ uschar *data;
 uschar *readerror = US"";
 void (*oldsignal)(int);
 
-DEBUG(D_route) debug_printf("rda_interpret (%s): %s\n",
-  (rdata->isfile)? "file" : "string", rdata->string);
+DEBUG(D_route) debug_printf("rda_interpret (%s): '%s'\n",
+  rdata->isfile ? "file" : "string", string_printing(rdata->string));
 
 /* Do the expansions of the file name or data first, while still privileged. */
 
-data = expand_string(rdata->string);
-if (data == NULL)
+if (!(data = expand_string(rdata->string)))
   {
   if (f.expand_string_forcedfail) return FF_NOTDELIVERED;
   *error = string_sprintf("failed to expand \"%s\": %s", rdata->string,
@@ -573,7 +570,8 @@ if (data == NULL)
   }
 rdata->string = data;
 
-DEBUG(D_route) debug_printf("expanded: %s\n", data);
+DEBUG(D_route)
+  debug_printf("expanded: '%s'%s\n", data, is_tainted(data) ? " (tainted)":"");
 
 if (rdata->isfile && data[0] != '/')
   {
@@ -590,11 +588,9 @@ if (!ugid->uid_set ||                         /* Either there's no uid, or */
     (!rdata->isfile &&                        /* We've got the data, and */
      rda_is_filter(data) == FILTER_FORWARD && /* It's not a filter script, */
      Ustrstr(data, ":include:") == NULL))     /* and there's no :include: */
-  {
   return rda_extract(rdata, options, include_directory,
     sieve_vacation_directory, sieve_enotify_mailto_owner, sieve_useraddress,
     sieve_subaddress, generated, error, eblockp, filtertype);
-  }
 
 /* We need to run the processing code in a sub-process. However, if we can
 determine the non-existence of a file first, we can decline without having to
@@ -620,12 +616,17 @@ with the parent process. */
 oldsignal = signal(SIGCHLD, SIG_DFL);
 search_tidyup();
 
-if ((pid = fork()) == 0)
+if ((pid = exim_fork(US"router-interpret")) == 0)
   {
   header_line *waslast = header_last;   /* Save last header */
+  int fd_flags = -1;
 
   fd = pfd[pipe_write];
   (void)close(pfd[pipe_read]);
+
+  if ((fd_flags = fcntl(fd, F_GETFD)) == -1) goto bad;
+  if (fcntl(fd, F_SETFD, fd_flags | FD_CLOEXEC) == -1) goto bad;
+
   exim_setugid(ugid->uid, ugid->gid, FALSE, rname);
 
   /* Addresses can get rewritten in filters; if we are not root or the exim
@@ -656,10 +657,9 @@ if ((pid = fork()) == 0)
 
   /* Pass back the contents of any syntax error blocks if we have a pointer */
 
-  if (eblockp != NULL)
+  if (eblockp)
     {
-    error_block *ep;
-    for (ep = *eblockp; ep != NULL; ep = ep->next)
+    for (error_block * ep = *eblockp; ep; ep = ep->next)
       if (  rda_write_string(fd, ep->text1) != 0
          || rda_write_string(fd, ep->text2) != 0
 	 )
@@ -675,8 +675,7 @@ if ((pid = fork()) == 0)
   if (f.system_filtering)
     {
     int i = 0;
-    header_line *h;
-    for (h = header_list; h != waslast->next; i++, h = h->next)
+    for (header_line * h = header_list; h != waslast->next; i++, h = h->next)
       if (  h->type == htype_old
          && write(fd, &i, sizeof(i)) != sizeof(i)
 	 )
@@ -714,8 +713,7 @@ if ((pid = fork()) == 0)
   if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
       yield == FF_FAIL || yield == FF_FREEZE)
     {
-    address_item *addr;
-    for (addr = *generated; addr; addr = addr->next)
+    for (address_item * addr = *generated; addr; addr = addr->next)
       {
       int reply_options = 0;
       int ig_err = addr->prop.ignore_error ? 1 : 0;
@@ -729,12 +727,9 @@ if ((pid = fork()) == 0)
 	goto bad;
 
       if (addr->pipe_expandn)
-        {
-        uschar **pp;
-        for (pp = addr->pipe_expandn; *pp; pp++)
+        for (uschar ** pp = addr->pipe_expandn; *pp; pp++)
           if (rda_write_string(fd, *pp) != 0)
 	    goto bad;
-        }
       if (rda_write_string(fd, NULL) != 0)
         goto bad;
 
@@ -779,7 +774,7 @@ if ((pid = fork()) == 0)
 out:
   (void)close(fd);
   search_tidyup();
-  _exit(0);
+  exim_underbar_exit(EXIT_SUCCESS);
 
 bad:
   DEBUG(D_rewrite) debug_printf("rda_interpret: failed write to pipe\n");
@@ -809,13 +804,12 @@ if (read(fd, filtertype, sizeof(int)) != sizeof(int) ||
 if (eblockp)
   {
   error_block *e;
-  error_block **p;
-  for (p = eblockp; ; p = &e->next)
+  for (error_block ** p = eblockp; ; p = &e->next)
     {
     uschar *s;
     if (!rda_read_string(fd, &s)) goto DISASTER;
     if (!s) break;
-    e = store_get(sizeof(error_block));
+    e = store_get(sizeof(error_block), GET_UNTAINTED);
     e->next = NULL;
     e->text1 = s;
     if (!rda_read_string(fd, &s)) goto DISASTER;
@@ -879,7 +873,7 @@ if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
     /* First string is the address; NULL => end of addresses */
 
     if (!rda_read_string(fd, &recipient)) goto DISASTER;
-    if (recipient == NULL) break;
+    if (!recipient) break;
 
     /* Hang on the end of the chain */
 
@@ -914,7 +908,7 @@ if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
 
     if (i > 0)
       {
-      addr->pipe_expandn = store_get((i+1) * sizeof(uschar *));
+      addr->pipe_expandn = store_get((i+1) * sizeof(uschar *), GET_UNTAINTED);
       addr->pipe_expandn[i] = NULL;
       while (--i >= 0) addr->pipe_expandn[i] = expandn[i];
       }
@@ -924,7 +918,7 @@ if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
     if (read(fd, &reply_options, sizeof(int)) != sizeof(int)) goto DISASTER;
     if ((reply_options & REPLY_EXISTS) != 0)
       {
-      addr->reply = store_get(sizeof(reply_item));
+      addr->reply = store_get(sizeof(reply_item), GET_UNTAINTED);
 
       addr->reply->file_expand = (reply_options & REPLY_EXPAND) != 0;
       addr->reply->return_message = (reply_options & REPLY_RETURN) != 0;
@@ -933,17 +927,17 @@ if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
             sizeof(int) ||
           read(fd,&(addr->reply->once_repeat),sizeof(time_t)) !=
             sizeof(time_t) ||
-          !rda_read_string(fd, &(addr->reply->to)) ||
-          !rda_read_string(fd, &(addr->reply->cc)) ||
-          !rda_read_string(fd, &(addr->reply->bcc)) ||
-          !rda_read_string(fd, &(addr->reply->from)) ||
-          !rda_read_string(fd, &(addr->reply->reply_to)) ||
-          !rda_read_string(fd, &(addr->reply->subject)) ||
-          !rda_read_string(fd, &(addr->reply->headers)) ||
-          !rda_read_string(fd, &(addr->reply->text)) ||
-          !rda_read_string(fd, &(addr->reply->file)) ||
-          !rda_read_string(fd, &(addr->reply->logfile)) ||
-          !rda_read_string(fd, &(addr->reply->oncelog)))
+          !rda_read_string(fd, &addr->reply->to) ||
+          !rda_read_string(fd, &addr->reply->cc) ||
+          !rda_read_string(fd, &addr->reply->bcc) ||
+          !rda_read_string(fd, &addr->reply->from) ||
+          !rda_read_string(fd, &addr->reply->reply_to) ||
+          !rda_read_string(fd, &addr->reply->subject) ||
+          !rda_read_string(fd, &addr->reply->headers) ||
+          !rda_read_string(fd, &addr->reply->text) ||
+          !rda_read_string(fd, &addr->reply->file) ||
+          !rda_read_string(fd, &addr->reply->logfile) ||
+          !rda_read_string(fd, &addr->reply->oncelog))
         goto DISASTER;
       }
     }
@@ -954,13 +948,11 @@ reading end of the pipe, and we are done. */
 
 WAIT_EXIT:
 while ((rc = wait(&status)) != pid)
-  {
   if (rc < 0 && errno == ECHILD)      /* Process has vanished */
     {
     log_write(0, LOG_MAIN, "redirection process %d vanished unexpectedly", pid);
     goto FINAL_EXIT;
     }
-  }
 
 DEBUG(D_route)
   debug_printf("rda_interpret: subprocess yield=%d error=%s\n", yield, *error);
@@ -970,16 +962,14 @@ if (had_disaster)
   *error = string_sprintf("internal problem in %s: failure to transfer "
     "data from subprocess: status=%04x%s%s%s", rname,
     status, readerror,
-    (*error == NULL)? US"" : US": error=",
-    (*error == NULL)? US"" : *error);
+    *error ? US": error=" : US"",
+    *error ? *error : US"");
   log_write(0, LOG_MAIN|LOG_PANIC, "%s", *error);
   }
 else if (status != 0)
-  {
   log_write(0, LOG_MAIN|LOG_PANIC, "internal problem in %s: unexpected status "
     "%04x from redirect subprocess (but data correctly received)", rname,
     status);
-  }
 
 FINAL_EXIT:
 (void)close(fd);