path: root/shared/nm-glib-aux/nm-secret-utils.h

// SPDX-License-Identifier: LGPL-2.1+
/*
 * Copyright (C) 2018 Red Hat, Inc.
 */

#ifndef __NM_SECRET_UTILS_H__
#define __NM_SECRET_UTILS_H__

#include "nm-macros-internal.h"

/*****************************************************************************/

void nm_explicit_bzero (void *s, gsize n);

/*****************************************************************************/

char *nm_secret_strchomp (char *secret);

/*****************************************************************************/

void nm_free_secret (char *secret);

NM_AUTO_DEFINE_FCN0 (char *, _nm_auto_free_secret, nm_free_secret)
/**
 * nm_auto_free_secret:
 *
 * Call g_free() on a variable location when it goes out of scope.
 * Also, previously, calls memset(loc, 0, strlen(loc)) to clear out
 * the secret.
 */
#define nm_auto_free_secret nm_auto(_nm_auto_free_secret)

/*****************************************************************************/

GBytes *nm_secret_copy_to_gbytes (gconstpointer mem, gsize mem_len);

/*****************************************************************************/

/* NMSecretPtr is a pair of malloc'ed data pointer and the length of the
 * data. The purpose is to use it in combination with nm_auto_clear_secret_ptr
 * which ensures that the data pointer (with all len bytes) is cleared upon
 * cleanup. */
typedef struct {
	gsize len;

	/* the data pointer. This pointer must be allocated with malloc (at least
	 * when used with nm_secret_ptr_clear()). */
	union {
		char *str;
		void *ptr;
		guint8 *bin;
	};
} NMSecretPtr;

static inline void
nm_secret_ptr_bzero (NMSecretPtr *secret)
{
	if (secret) {
		if (secret->len > 0) {
			if (secret->ptr)
				nm_explicit_bzero (secret->ptr, secret->len);
		}
	}
}

#define nm_auto_bzero_secret_ptr nm_auto(nm_secret_ptr_bzero)

static inline void
nm_secret_ptr_clear (NMSecretPtr *secret)
{
	if (secret) {
		if (secret->len > 0) {
			if (secret->ptr)
				nm_explicit_bzero (secret->ptr, secret->len);
			secret->len = 0;
		}
		nm_clear_g_free (&secret->ptr);
	}
}

#define nm_auto_clear_secret_ptr nm_auto(nm_secret_ptr_clear)

#define NM_SECRET_PTR_INIT() \
	((const NMSecretPtr) { \
		.len = 0, \
		.ptr = NULL, \
	})

#define NM_SECRET_PTR_STATIC(_len) \
	((const NMSecretPtr) { \
		.len = _len, \
		.ptr = ((guint8 [_len]) { }), \
	})

#define NM_SECRET_PTR_ARRAY(_arr) \
	((const NMSecretPtr) { \
		.len = G_N_ELEMENTS (_arr) * sizeof ((_arr)[0]), \
		.ptr = &((_arr)[0]), \
	})

static inline void
nm_secret_ptr_clear_static (const NMSecretPtr *secret)
{
	if (secret) {
		if (secret->len > 0) {
			nm_assert (secret->ptr);
			nm_explicit_bzero (secret->ptr, secret->len);
		}
	}
}

#define nm_auto_clear_static_secret_ptr nm_auto(nm_secret_ptr_clear_static)

static inline void
nm_secret_ptr_move (NMSecretPtr *dst, NMSecretPtr *src)
{
	if (dst && dst != src) {
		*dst = *src;
		src->len = 0;
		src->ptr = NULL;
	}
}

/*****************************************************************************/

typedef struct {
	const gsize len;
	union {
		char str[0];
		guint8 bin[0];
	};
} NMSecretBuf;

static inline void
_nm_auto_free_secret_buf (NMSecretBuf **ptr)
{
	NMSecretBuf *b = *ptr;

	if (b) {
		nm_assert (b->len > 0);
		nm_explicit_bzero (b->bin, b->len);
		g_free (b);
	}
}
#define nm_auto_free_secret_buf nm_auto(_nm_auto_free_secret_buf)

NMSecretBuf *nm_secret_buf_new (gsize len);

GBytes *nm_secret_buf_to_gbytes_take (NMSecretBuf *secret, gssize actual_len);

/*****************************************************************************/

gboolean nm_utils_memeqzero_secret (gconstpointer data, gsize length);

/*****************************************************************************/

/**
 * nm_secret_mem_realloc:
 * @m_old: the current buffer of length @cur_len.
 * @do_bzero_mem: if %TRUE, bzero the old buffer
 * @cur_len: the current buffer length of @m_old. It is necessary for bzero.
 * @new_len: the desired new length
 *
 * If @do_bzero_mem is false, this is like g_realloc().
 * Otherwise, this will allocate a new buffer of the desired size, copy over the
 * old data, and bzero the old buffer before freeing it. As such, it also behaves
 * similar to g_realloc(), with the overhead of nm_explicit_bzero() and using
 * malloc/free intead of realloc().
 *
 * Returns: the new allocated buffer. Think of it behaving like g_realloc().
 */
static inline gpointer
nm_secret_mem_realloc (gpointer m_old, gboolean do_bzero_mem, gsize cur_len, gsize new_len)
{
	gpointer m_new;

	nm_assert (m_old || cur_len == 0);

	if (   do_bzero_mem
	    && G_LIKELY (cur_len > 0)) {
		m_new = g_malloc (new_len);
		if (G_LIKELY (new_len > 0))
			memcpy (m_new, m_old, NM_MIN (cur_len, new_len));
		nm_explicit_bzero (m_old, cur_len);
		g_free (m_old);
	} else
		m_new = g_realloc (m_old, new_len);

	return m_new;
}

/**
 * nm_secret_mem_try_realloc:
 * @m_old: the current buffer of length @cur_len.
 * @do_bzero_mem: if %TRUE, bzero the old buffer
 * @cur_len: the current buffer length of @m_old. It is necessary for bzero.
 * @new_len: the desired new length
 *
 * If @do_bzero_mem is false, this is like g_try_realloc().
 * Otherwise, this will try to allocate a new buffer of the desired size, copy over the
 * old data, and bzero the old buffer before freeing it. As such, it also behaves
 * similar to g_try_realloc(), with the overhead of nm_explicit_bzero() and using
 * malloc/free intead of realloc().
 *
 * Returns: the new allocated buffer or NULL. Think of it behaving like g_try_realloc().
 */
static inline gpointer
nm_secret_mem_try_realloc (gpointer m_old, gboolean do_bzero_mem, gsize cur_len, gsize new_len)
{
	gpointer m_new;

	nm_assert (m_old || cur_len == 0);

	if (   do_bzero_mem
	    && G_LIKELY (cur_len > 0)) {
		if (G_UNLIKELY (new_len == 0))
			m_new = NULL;
		else {
			m_new = g_try_malloc (new_len);
			if (!m_new)
				return NULL;
			memcpy (m_new, m_old, NM_MIN (cur_len, new_len));
		}
		nm_explicit_bzero (m_old, cur_len);
		g_free (m_old);
		return m_new;
	}

	return g_try_realloc (m_old, new_len);
}

/**
 * nm_secret_mem_try_realloc_take:
 * @m_old: the current buffer of length @cur_len.
 * @do_bzero_mem: if %TRUE, bzero the old buffer
 * @cur_len: the current buffer length of @m_old. It is necessary for bzero.
 * @new_len: the desired new length
 *
 * This works like nm_secret_mem_try_realloc(), which is not unlike g_try_realloc().
 * The difference is, if we fail to allocate a new buffer, then @m_old will be
 * freed (and possibly cleared). This differs from plain realloc(), where the
 * old buffer is unchanged if the operation fails.
 *
 * Returns: the new allocated buffer or NULL. Think of it behaving like g_try_realloc()
 *   but it will always free @m_old.
 */
static inline gpointer
nm_secret_mem_try_realloc_take (gpointer m_old, gboolean do_bzero_mem, gsize cur_len, gsize new_len)
{
	gpointer m_new;

	nm_assert (m_old || cur_len == 0);

	if (   do_bzero_mem
	    && G_LIKELY (cur_len > 0)) {
		if (G_UNLIKELY (new_len == 0))
			m_new = NULL;
		else {
			m_new = g_try_malloc (new_len);
			if (G_LIKELY (m_new))
				memcpy (m_new, m_old, NM_MIN (cur_len, new_len));
		}
		nm_explicit_bzero (m_old, cur_len);
		g_free (m_old);
		return m_new;
	}

	m_new = g_try_realloc (m_old, new_len);
	if (G_UNLIKELY (!m_new && new_len > 0))
		g_free (m_old);
	return m_new;
}

/*****************************************************************************/

#endif /* __NM_SECRET_UTILS_H__ */