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/*
* Copyright (C) Red Hat, Inc.
*
* SPDX-License-Identifier: LGPL-2.0+
*
* This 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 of the License, or (at your option) any later version.
*
* This 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 this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <sys/ioctl.h>
#include "ostree-core-private.h"
#include "ostree-repo-private.h"
#include "otutil.h"
#include "ot-fs-utils.h"
#ifdef HAVE_LINUX_FSVERITY_H
#include <linux/fsverity.h>
#endif
gboolean
_ostree_repo_parse_fsverity_config (OstreeRepo *self, GError **error)
{
/* Currently experimental */
static const char fsverity_key[] = "ex-fsverity";
self->fs_verity_wanted = _OSTREE_FEATURE_NO;
#ifdef HAVE_LINUX_FSVERITY_H
self->fs_verity_supported = _OSTREE_FEATURE_MAYBE;
#else
self->fs_verity_supported = _OSTREE_FEATURE_NO;
#endif
gboolean fsverity_required = FALSE;
if (!ot_keyfile_get_boolean_with_default (self->config, fsverity_key, "required",
FALSE, &fsverity_required, error))
return FALSE;
if (fsverity_required)
{
self->fs_verity_wanted = _OSTREE_FEATURE_YES;
if (self->fs_verity_supported == _OSTREE_FEATURE_NO)
return glnx_throw (error, "fsverity required, but libostree compiled without support");
}
else
{
gboolean fsverity_opportunistic = FALSE;
if (!ot_keyfile_get_boolean_with_default (self->config, fsverity_key, "opportunistic",
FALSE, &fsverity_opportunistic, error))
return FALSE;
if (fsverity_opportunistic)
self->fs_verity_wanted = _OSTREE_FEATURE_MAYBE;
}
return TRUE;
}
/* Wrapper around the fsverity ioctl, compressing the result to
* "success, unsupported or error". This is used for /boot where
* we enable verity if supported.
* */
gboolean
_ostree_tmpf_fsverity_core (GLnxTmpfile *tmpf,
_OstreeFeatureSupport fsverity_requested,
gboolean *supported,
GError **error)
{
/* Set this by default to simplify the code below */
if (supported)
*supported = FALSE;
if (fsverity_requested == _OSTREE_FEATURE_NO)
return TRUE;
#ifdef HAVE_LINUX_FSVERITY_H
GLNX_AUTO_PREFIX_ERROR ("fsverity", error);
/* fs-verity requires a read-only file descriptor */
if (!glnx_tmpfile_reopen_rdonly (tmpf, error))
return FALSE;
struct fsverity_enable_arg arg = { 0, };
arg.version = 1;
arg.hash_algorithm = FS_VERITY_HASH_ALG_SHA256; /* TODO configurable? */
arg.block_size = 4096; /* FIXME query */
arg.salt_size = 0; /* TODO store salt in ostree repo config */
arg.salt_ptr = 0;
arg.sig_size = 0; /* We don't currently expect use of in-kernel signature verification */
arg.sig_ptr = 0;
if (ioctl (tmpf->fd, FS_IOC_ENABLE_VERITY, &arg) < 0)
{
switch (errno)
{
case ENOTTY:
case EOPNOTSUPP:
return TRUE;
default:
return glnx_throw_errno_prefix (error, "ioctl(FS_IOC_ENABLE_VERITY)");
}
}
if (supported)
*supported = TRUE;
#endif
return TRUE;
}
/* Enable verity on a file, respecting the "wanted" and "supported" states.
* The main idea here is to optimize out pointlessly calling the ioctl()
* over and over in cases where it's not supported for the repo's filesystem,
* as well as to support "opportunistic" use (requested and if filesystem supports).
* */
gboolean
_ostree_tmpf_fsverity (OstreeRepo *self,
GLnxTmpfile *tmpf,
GError **error)
{
#ifdef HAVE_LINUX_FSVERITY_H
g_mutex_lock (&self->txn_lock);
_OstreeFeatureSupport fsverity_wanted = self->fs_verity_wanted;
_OstreeFeatureSupport fsverity_supported = self->fs_verity_supported;
g_mutex_unlock (&self->txn_lock);
switch (fsverity_wanted)
{
case _OSTREE_FEATURE_YES:
{
if (fsverity_supported == _OSTREE_FEATURE_NO)
return glnx_throw (error, "fsverity required but filesystem does not support it");
}
break;
case _OSTREE_FEATURE_MAYBE:
break;
case _OSTREE_FEATURE_NO:
return TRUE;
}
gboolean supported = FALSE;
if (!_ostree_tmpf_fsverity_core (tmpf, fsverity_wanted, &supported, error))
return FALSE;
if (!supported)
{
if (G_UNLIKELY (fsverity_wanted == _OSTREE_FEATURE_YES))
return glnx_throw (error, "fsverity required but filesystem does not support it");
/* If we got here, we must be trying "opportunistic" use of fs-verity */
g_assert_cmpint (fsverity_wanted, ==, _OSTREE_FEATURE_MAYBE);
g_mutex_lock (&self->txn_lock);
self->fs_verity_supported = _OSTREE_FEATURE_NO;
g_mutex_unlock (&self->txn_lock);
return TRUE;
}
g_mutex_lock (&self->txn_lock);
self->fs_verity_supported = _OSTREE_FEATURE_YES;
g_mutex_unlock (&self->txn_lock);
#else
g_assert_cmpint (self->fs_verity_wanted, !=, _OSTREE_FEATURE_YES);
#endif
return TRUE;
}
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