b232508707
We already had nm_free_secret() to clear the secret out of a NUL terminated string. That works well for secrets which are strings, it can be used with a cleanup attribute (nm_auto_free_secret) and as a cleanup function for a GBytes. However, it does not work for secrets which are binary. For those, we must also track the length of the allocated data and clear it. Add two new structs NMSecretPtr and NMSecretBuf to help with that.
135 lines
3.7 KiB
C
135 lines
3.7 KiB
C
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
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/* NetworkManager -- Network link manager
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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* (C) Copyright 2018 Red Hat, Inc.
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*/
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#include "nm-default.h"
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#include "nm-secret-utils.h"
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/*****************************************************************************/
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void
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nm_explicit_bzero (void *s, gsize n)
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{
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/* gracefully handle n == 0. This is important, callers rely on it. */
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if (n > 0) {
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nm_assert (s);
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#if defined (HAVE_DECL_EXPLICIT_BZERO) && HAVE_DECL_EXPLICIT_BZERO
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explicit_bzero (s, n);
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#else
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/* don't bother with a workaround. Use a reasonable glibc. */
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memset (s, 0, n);
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#endif
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}
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}
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/*****************************************************************************/
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char *
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nm_secret_strchomp (char *secret)
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{
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gsize len;
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g_return_val_if_fail (secret, NULL);
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/* it's actually identical to g_strchomp(). However,
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* the glib function does not document, that it clears the
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* memory. For @secret, we don't only want to truncate trailing
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* spaces, we want to overwrite them with NUL. */
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len = strlen (secret);
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while (len--) {
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if (g_ascii_isspace ((guchar) secret[len]))
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secret[len] = '\0';
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else
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break;
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}
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return secret;
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}
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/*****************************************************************************/
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GBytes *
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nm_secret_copy_to_gbytes (gconstpointer mem, gsize mem_len)
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{
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NMSecretBuf *b;
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if (mem_len == 0)
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return g_bytes_new_static ("", 0);
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nm_assert (mem);
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/* NUL terminate the buffer.
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*
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* The entire buffer is already malloc'ed and likely has some room for padding.
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* Thus, in many situations, this additional byte will cause no overhead in
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* practice.
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*
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* Even if it causes an overhead, do it just for safety. Yes, the returned
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* bytes is not a NUL terminated string and no user must rely on this. Do
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* not treat binary data as NUL terminated strings, unless you know what
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* you are doing. Anyway, defensive FTW.
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*/
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b = nm_secret_buf_new (mem_len + 1);
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memcpy (b->bin, mem, mem_len);
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b->bin[mem_len] = 0;
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return nm_secret_buf_to_gbytes_take (b, mem_len);
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}
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/*****************************************************************************/
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NMSecretBuf *
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nm_secret_buf_new (gsize len)
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{
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NMSecretBuf *secret;
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nm_assert (len > 0);
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secret = g_malloc (sizeof (NMSecretBuf) + len);
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*((gsize *) &(secret->len)) = len;
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return secret;
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}
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static void
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_secret_buf_free (gpointer user_data)
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{
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NMSecretBuf *secret = user_data;
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nm_assert (secret);
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nm_assert (secret->len > 0);
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nm_explicit_bzero (secret->bin, secret->len);
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g_free (user_data);
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}
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GBytes *
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nm_secret_buf_to_gbytes_take (NMSecretBuf *secret, gssize actual_len)
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{
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nm_assert (secret);
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nm_assert (secret->len > 0);
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nm_assert (actual_len == -1 || (actual_len >= 0 && actual_len <= secret->len));
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return g_bytes_new_with_free_func (secret->bin,
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actual_len >= 0 ? (gsize) actual_len : secret->len,
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_secret_buf_free,
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secret);
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}
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