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authorFlorian Weimer <fweimer@redhat.com>2015-10-02 11:34:13 +0200
committerFlorian Weimer <fweimer@redhat.com>2015-10-02 11:34:13 +0200
commit676599b36a92f3c201c5682ee7a5caddd9f370a4 (patch)
tree6860752c26ccab76ee9db5e60ff465d1edf25feb /nss/valid_field.c
parentb0f81637d5bda47be93bac34b68f429a12979321 (diff)
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Harden putpwent, putgrent, putspent, putspent against injection [BZ #18724]
This prevents injection of ':' and '\n' into output functions which
use the NSS files database syntax.  Critical fields (user/group names
and file system paths) are checked strictly.  For backwards
compatibility, the GECOS field is rewritten instead.

The getent program is adjusted to use the put*ent functions in libc,
instead of local copies.  This changes the behavior of getent if user
names start with '-' or '+'.
Diffstat (limited to 'nss/valid_field.c')
-rw-r--r--nss/valid_field.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/nss/valid_field.c b/nss/valid_field.c
new file mode 100644
index 0000000000..5fcddc50ae
--- /dev/null
+++ b/nss/valid_field.c
@@ -0,0 +1,31 @@
+/* Copyright (C) 2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <nss.h>
+#include <string.h>
+
+const char __nss_invalid_field_characters[] = NSS_INVALID_FIELD_CHARACTERS;
+
+/* Check that VALUE is either NULL or a NUL-terminated string which
+   does not contain characters not permitted in NSS database
+   fields.  */
+_Bool
+__nss_valid_field (const char *value)
+{
+  return value == NULL
+    || strpbrk (value, __nss_invalid_field_characters) == NULL;
+}