Adding upstream version 2.38.1.upstream/2.38.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 566 insertions, 0 deletions

diff --git a/libmount/src/context_veritydev.c b/libmount/src/context_veritydev.c
new file mode 100644
index 0000000..a8cb1f6
--- /dev/null
+++ b/libmount/src/context_veritydev.c
@@ -0,0 +1,566 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * This file is part of libmount from util-linux project.
+ *
+ * Copyright (C) 2019 Microsoft Corporation
+ *
+ * libmount 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.
+ */
+
+#include "mountP.h"
+
+#if defined(HAVE_CRYPTSETUP)
+
+#ifdef CRYPTSETUP_VIA_DLOPEN
+#include <dlfcn.h>
+#endif
+#include <libcryptsetup.h>
+#include "path.h"
+
+#ifdef CRYPTSETUP_VIA_DLOPEN
+static void *get_symbol(struct libmnt_context *cxt, void *dl, const char *name, int *rc)
+{
+	char *dl_error = NULL;
+	void *sym = dlsym(dl, name);
+
+	*rc = 0;
+	if ((dl_error = dlerror()) == NULL)
+		return sym;
+
+	DBG(VERITY, ul_debugobj(cxt, "veritydev specific options detected but cannot dlopen symbol %s: %s", name, dl_error));
+	*rc = -ENOTSUP;
+
+	return NULL;
+}
+#endif
+
+static void libcryptsetup_log(int level __attribute__((__unused__)), const char *msg, void *data)
+{
+	struct libmnt_context *cxt = (struct libmnt_context *)data;
+
+	DBG(VERITY, ul_debugobj(cxt, "cryptsetup: %s", msg));
+}
+
+/* Taken from https://gitlab.com/cryptsetup/cryptsetup/blob/master/lib/utils_crypt.c#L225 */
+static size_t crypt_hex_to_bytes(const char *hex, char **result)
+{
+	char buf[3] = "xx\0", *endp, *bytes;
+	size_t i, len;
+
+	len = strlen(hex);
+	if (len % 2)
+		return -EINVAL;
+	len /= 2;
+
+	bytes = malloc(len);
+	if (!bytes)
+		return -ENOMEM;
+
+	for (i = 0; i < len; i++) {
+		memcpy(buf, &hex[i * 2], 2);
+		errno = 0;
+		bytes[i] = strtoul(buf, &endp, 16);
+		if (errno || endp != &buf[2]) {
+			free(bytes);
+			return -EINVAL;
+		}
+	}
+	*result = bytes;
+	return i;
+}
+
+
+int mnt_context_setup_veritydev(struct libmnt_context *cxt)
+{
+	const char *backing_file, *optstr;
+	char *val = NULL, *key = NULL, *root_hash_binary = NULL, *mapper_device = NULL,
+		*mapper_device_full = NULL, *backing_file_basename = NULL, *root_hash = NULL,
+		*hash_device = NULL, *root_hash_file = NULL, *fec_device = NULL, *hash_sig = NULL,
+		*root_hash_sig_file = NULL;
+	size_t len, hash_size, hash_sig_size = 0, keysize = 0;
+	struct crypt_params_verity crypt_params = {};
+	struct crypt_device *crypt_dev = NULL;
+	int rc = 0;
+	/* Use the same default for FEC parity bytes as cryptsetup uses */
+	uint64_t offset = 0, fec_offset = 0, fec_roots = 2;
+	uint32_t crypt_activate_flags = CRYPT_ACTIVATE_READONLY;
+	struct stat hash_sig_st;
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	/* To avoid linking libmount to libcryptsetup, and keep the default dependencies list down, use dlopen */
+	void *dl = NULL;
+	void (*sym_crypt_set_debug_level)(int) = NULL;
+	void (*sym_crypt_set_log_callback)(struct crypt_device *, void (*log)(int, const char *, void *), void *) = NULL;
+	int (*sym_crypt_init_data_device)(struct crypt_device **, const char *, const char *) = NULL;
+	int (*sym_crypt_load)(struct crypt_device *, const char *, void *) = NULL;
+	int (*sym_crypt_get_volume_key_size)(struct crypt_device *) = NULL;
+#ifdef HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
+	int (*sym_crypt_activate_by_signed_key)(struct crypt_device *, const char *, const char *, size_t, const char *, size_t, uint32_t) = NULL;
+#endif
+	int (*sym_crypt_activate_by_volume_key)(struct crypt_device *, const char *, const char *, size_t, uint32_t) = NULL;
+	void (*sym_crypt_free)(struct crypt_device *) = NULL;
+	int (*sym_crypt_init_by_name)(struct crypt_device **, const char *) = NULL;
+	int (*sym_crypt_get_verity_info)(struct crypt_device *, struct crypt_params_verity *) = NULL;
+	int (*sym_crypt_volume_key_get)(struct crypt_device *, int, char *, size_t *, const char *, size_t) = NULL;
+#else
+	void (*sym_crypt_set_debug_level)(int) = &crypt_set_debug_level;
+	void (*sym_crypt_set_log_callback)(struct crypt_device *, void (*log)(int, const char *, void *), void *) = &crypt_set_log_callback;
+	int (*sym_crypt_init_data_device)(struct crypt_device **, const char *, const char *) = &crypt_init_data_device;
+	int (*sym_crypt_load)(struct crypt_device *, const char *, void *) = &crypt_load;
+	int (*sym_crypt_get_volume_key_size)(struct crypt_device *) = &crypt_get_volume_key_size;
+#ifdef HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
+	int (*sym_crypt_activate_by_signed_key)(struct crypt_device *, const char *, const char *, size_t, const char *, size_t, uint32_t) = &crypt_activate_by_signed_key;
+#endif
+	int (*sym_crypt_activate_by_volume_key)(struct crypt_device *, const char *, const char *, size_t, uint32_t) = &crypt_activate_by_volume_key;
+	void (*sym_crypt_free)(struct crypt_device *) = &crypt_free;
+	int (*sym_crypt_init_by_name)(struct crypt_device **, const char *) = &crypt_init_by_name;
+	int (*sym_crypt_get_verity_info)(struct crypt_device *, struct crypt_params_verity *) = &crypt_get_verity_info;
+	int (*sym_crypt_volume_key_get)(struct crypt_device *, int, char *, size_t *, const char *, size_t) = &crypt_volume_key_get;
+#endif
+
+	assert(cxt);
+	assert(cxt->fs);
+	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
+
+	/* dm-verity volumes are read-only, and mount will fail if not set */
+	mnt_context_set_mflags(cxt, (cxt->mountflags | MS_RDONLY));
+
+	backing_file = mnt_fs_get_srcpath(cxt->fs);
+	if (!backing_file)
+		return -EINVAL;
+
+	/* To avoid clashes, prefix libmnt_ to all mapper devices */
+	backing_file_basename = basename(backing_file);
+	mapper_device = calloc(strlen(backing_file_basename) + strlen("libmnt_") + 1, sizeof(char));
+	if (!mapper_device)
+		return -ENOMEM;
+	strcat(mapper_device, "libmnt_");
+	strcat(mapper_device, backing_file_basename);
+
+	DBG(VERITY, ul_debugobj(cxt, "trying to setup verity device for %s", backing_file));
+
+	optstr = mnt_fs_get_user_options(cxt->fs);
+
+	/*
+	 * verity.hashdevice=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_HASH_DEVICE) &&
+	    mnt_optstr_get_option(optstr, "verity.hashdevice", &val, &len) == 0 && val) {
+		hash_device = strndup(val, len);
+		rc = hash_device ? 0 : -ENOMEM;
+	}
+
+	/*
+	 * verity.roothash=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_ROOT_HASH) &&
+	    mnt_optstr_get_option(optstr, "verity.roothash", &val, &len) == 0 && val) {
+		root_hash = strndup(val, len);
+		rc = root_hash ? 0 : -ENOMEM;
+	}
+
+	/*
+	 * verity.hashoffset=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_HASH_OFFSET) &&
+	    mnt_optstr_get_option(optstr, "verity.hashoffset", &val, &len) == 0) {
+		rc = mnt_parse_offset(val, len, &offset);
+		if (rc) {
+			DBG(VERITY, ul_debugobj(cxt, "failed to parse verity.hashoffset="));
+			rc = -MNT_ERR_MOUNTOPT;
+		}
+	}
+
+	/*
+	 * verity.roothashfile=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_ROOT_HASH_FILE) &&
+	    mnt_optstr_get_option(optstr, "verity.roothashfile", &val, &len) == 0 && val) {
+		root_hash_file = strndup(val, len);
+		rc = root_hash_file ? 0 : -ENOMEM;
+	}
+
+	/*
+	 * verity.fecdevice=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_FEC_DEVICE) &&
+	    mnt_optstr_get_option(optstr, "verity.fecdevice", &val, &len) == 0 && val) {
+		fec_device = strndup(val, len);
+		rc = fec_device ? 0 : -ENOMEM;
+	}
+
+	/*
+	 * verity.fecoffset=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_FEC_OFFSET) &&
+	    mnt_optstr_get_option(optstr, "verity.fecoffset", &val, &len) == 0) {
+		rc = mnt_parse_offset(val, len, &fec_offset);
+		if (rc) {
+			DBG(VERITY, ul_debugobj(cxt, "failed to parse verity.fecoffset="));
+			rc = -MNT_ERR_MOUNTOPT;
+		}
+	}
+
+	/*
+	 * verity.fecroots=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_FEC_ROOTS) &&
+	    mnt_optstr_get_option(optstr, "verity.fecroots", &val, &len) == 0) {
+		rc = mnt_parse_offset(val, len, &fec_roots);
+		if (rc) {
+			DBG(VERITY, ul_debugobj(cxt, "failed to parse verity.fecroots="));
+			rc = -MNT_ERR_MOUNTOPT;
+		}
+	}
+
+	/*
+	 * verity.roothashsig=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_ROOT_HASH_SIG) &&
+	    mnt_optstr_get_option(optstr, "verity.roothashsig", &val, &len) == 0 && val) {
+		root_hash_sig_file = strndup(val, len);
+		rc = root_hash_sig_file ? 0 : -ENOMEM;
+		if (rc == 0)
+			rc = ul_path_stat(NULL, &hash_sig_st, 0, root_hash_sig_file);
+		if (rc == 0)
+			rc = !S_ISREG(hash_sig_st.st_mode) || !hash_sig_st.st_size ? -EINVAL : 0;
+		if (rc == 0) {
+			hash_sig_size = hash_sig_st.st_size;
+			hash_sig = malloc(hash_sig_size);
+			rc = hash_sig ? 0 : -ENOMEM;
+		}
+		if (rc == 0) {
+			rc = ul_path_read(NULL, hash_sig, hash_sig_size, root_hash_sig_file);
+			rc = rc < (int)hash_sig_size ? -1 : 0;
+		}
+	}
+
+	/*
+	 * verity.oncorruption=
+	 */
+	if (rc == 0 && (cxt->user_mountflags & MNT_MS_VERITY_ON_CORRUPTION) &&
+	    mnt_optstr_get_option(optstr, "verity.oncorruption", &val, &len) == 0) {
+		if (!strncmp(val, "ignore", len))
+			crypt_activate_flags |= CRYPT_ACTIVATE_IGNORE_CORRUPTION;
+		else if (!strncmp(val, "restart", len))
+			crypt_activate_flags |= CRYPT_ACTIVATE_RESTART_ON_CORRUPTION;
+		else if (!strncmp(val, "panic", len))
+			/* Added by libcryptsetup v2.3.4 - ignore on lower versions, as with other optional features */
+#ifdef CRYPT_ACTIVATE_PANIC_ON_CORRUPTION
+			crypt_activate_flags |= CRYPT_ACTIVATE_PANIC_ON_CORRUPTION;
+#else
+			DBG(VERITY, ul_debugobj(cxt, "verity.oncorruption=panic not supported by libcryptsetup, ignoring"));
+#endif
+		else {
+			DBG(VERITY, ul_debugobj(cxt, "failed to parse verity.oncorruption="));
+			rc = -MNT_ERR_MOUNTOPT;
+		}
+	}
+
+	if (!rc && root_hash && root_hash_file) {
+		DBG(VERITY, ul_debugobj(cxt, "verity.roothash and verity.roothashfile are mutually exclusive"));
+		rc = -EINVAL;
+	} else if (!rc && root_hash_file) {
+		rc = ul_path_read_string(NULL, &root_hash, root_hash_file);
+		rc = rc < 1 ? rc : 0;
+	}
+
+	if (!rc && (!hash_device || !root_hash)) {
+		DBG(VERITY, ul_debugobj(cxt, "verity.hashdevice and one of verity.roothash or verity.roothashfile are mandatory"));
+		rc = -EINVAL;
+	}
+
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	if (rc == 0) {
+		int dl_flags = RTLD_LAZY | RTLD_LOCAL;
+		/* glibc extension: mnt_context_deferred_delete_veritydev is called immediately after, don't unload on dl_close */
+#ifdef RTLD_NODELETE
+		dl_flags |= RTLD_NODELETE;
+#endif
+		/* glibc extension: might help to avoid further symbols clashes */
+#ifdef RTLD_DEEPBIND
+		dl_flags |= RTLD_DEEPBIND;
+#endif
+		dl = dlopen("libcryptsetup.so.12", dl_flags);
+		if (!dl) {
+			DBG(VERITY, ul_debugobj(cxt, "veritydev specific options detected but cannot dlopen libcryptsetup"));
+			rc = -ENOTSUP;
+		}
+	}
+
+	/* clear errors first, then load all the libcryptsetup symbols */
+	dlerror();
+
+	if (rc == 0)
+		*(void **)(&sym_crypt_set_debug_level) = get_symbol(cxt, dl, "crypt_set_debug_level", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_set_log_callback) = get_symbol(cxt, dl, "crypt_set_log_callback", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_init_data_device) = get_symbol(cxt, dl, "crypt_init_data_device", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_load) = get_symbol(cxt, dl, "crypt_load", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_get_volume_key_size) = get_symbol(cxt, dl, "crypt_get_volume_key_size", &rc);
+#ifdef HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
+	if (rc == 0)
+		*(void **)(&sym_crypt_activate_by_signed_key) = get_symbol(cxt, dl, "crypt_activate_by_signed_key", &rc);
+#endif
+	if (rc == 0)
+		*(void **)(&sym_crypt_activate_by_volume_key) = get_symbol(cxt, dl, "crypt_activate_by_volume_key", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_free) = get_symbol(cxt, dl, "crypt_free", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_init_by_name) = get_symbol(cxt, dl, "crypt_init_by_name", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_get_verity_info) = get_symbol(cxt, dl, "crypt_get_verity_info", &rc);
+	if (rc == 0)
+		*(void **)(&sym_crypt_volume_key_get) = get_symbol(cxt, dl, "crypt_volume_key_get", &rc);
+#endif
+	if (rc)
+		goto done;
+
+	if (mnt_context_is_verbose(cxt))
+		(*sym_crypt_set_debug_level)(CRYPT_DEBUG_ALL);
+	(*sym_crypt_set_log_callback)(NULL, libcryptsetup_log, cxt);
+
+	rc = (*sym_crypt_init_data_device)(&crypt_dev, hash_device, backing_file);
+	if (rc)
+		goto done;
+
+	memset(&crypt_params, 0, sizeof(struct crypt_params_verity));
+	crypt_params.hash_area_offset = offset;
+	crypt_params.fec_area_offset = fec_offset;
+	crypt_params.fec_roots = fec_roots;
+	crypt_params.fec_device = fec_device;
+	crypt_params.flags = 0;
+	rc = (*sym_crypt_load)(crypt_dev, CRYPT_VERITY, &crypt_params);
+	if (rc < 0)
+		goto done;
+
+	hash_size = (*sym_crypt_get_volume_key_size)(crypt_dev);
+	if (crypt_hex_to_bytes(root_hash, &root_hash_binary) != hash_size) {
+		DBG(VERITY, ul_debugobj(cxt, "root hash %s is not of length %zu", root_hash, hash_size));
+		rc = -EINVAL;
+		goto done;
+	}
+	if (hash_sig) {
+#ifdef HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
+		rc = (*sym_crypt_activate_by_signed_key)(crypt_dev, mapper_device, root_hash_binary, hash_size,
+				hash_sig, hash_sig_size, crypt_activate_flags);
+#else
+		rc = -EINVAL;
+		DBG(VERITY, ul_debugobj(cxt, "verity.roothashsig=%s passed but libcryptsetup does not provide crypt_activate_by_signed_key()", hash_sig));
+#endif
+	} else
+		rc = (*sym_crypt_activate_by_volume_key)(crypt_dev, mapper_device, root_hash_binary, hash_size,
+				crypt_activate_flags);
+	/*
+	 * If the mapper device already exists, and if libcryptsetup supports it, get the root
+	 * hash associated with the existing one and compare it with the parameter passed by
+	 * the user. If they match, then we can be sure the user intended to mount the exact
+	 * same device, and simply reuse it and return success.
+	 * The kernel does the refcounting for us.
+	 * If libcryptsetup does not support getting the root hash out of an existing device,
+	 * then return an error and tell the user that the device is already in use.
+	 * Pass through only OOM errors or mismatching root hash errors.
+	 */
+	if (rc == -EEXIST) {
+		DBG(VERITY, ul_debugobj(cxt, "%s already in use as /dev/mapper/%s", backing_file, mapper_device));
+		(*sym_crypt_free)(crypt_dev);
+		rc = (*sym_crypt_init_by_name)(&crypt_dev, mapper_device);
+		if (!rc) {
+			rc = (*sym_crypt_get_verity_info)(crypt_dev, &crypt_params);
+			if (!rc) {
+				key = calloc(hash_size, 1);
+				if (!key) {
+					rc = -ENOMEM;
+					goto done;
+				}
+			}
+			if (!rc) {
+				keysize = hash_size;
+				rc = (*sym_crypt_volume_key_get)(crypt_dev, CRYPT_ANY_SLOT, key, &keysize, NULL, 0);
+			}
+			if (!rc) {
+				DBG(VERITY, ul_debugobj(cxt, "comparing root hash of existing device with %s", root_hash));
+				if (memcmp(key, root_hash_binary, hash_size)) {
+					DBG(VERITY, ul_debugobj(cxt, "existing device's hash does not match with %s", root_hash));
+					rc = -EINVAL;
+					goto done;
+				}
+			} else {
+				DBG(VERITY, ul_debugobj(cxt, "libcryptsetup does not support extracting root hash of existing device"));
+			}
+		}
+		if (rc) {
+			rc = -EEXIST;
+		} else {
+			/*
+			 * Ensure that, if signatures are supported, we only reuse the device if the previous mount
+			 * used the same settings, so that a previous unsigned mount will not be reused if the user
+			 * asks to use signing for the new one, and viceversa.
+			 */
+#ifdef HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
+			if (!!hash_sig != !!(crypt_params.flags & CRYPT_VERITY_ROOT_HASH_SIGNATURE)) {
+				rc = -EINVAL;
+				DBG(VERITY, ul_debugobj(cxt, "existing device and new mount have to either be both opened with signature or both without"));
+				goto done;
+			}
+#endif
+			DBG(VERITY, ul_debugobj(cxt, "root hash of %s matches %s, reusing device", mapper_device, root_hash));
+		}
+	}
+
+	if (!rc) {
+		cxt->flags |= MNT_FL_VERITYDEV_READY;
+		mapper_device_full = calloc(strlen(mapper_device) + strlen("/dev/mapper/") + 1, sizeof(char));
+		if (!mapper_device_full)
+			rc = -ENOMEM;
+		else {
+			strcat(mapper_device_full, "/dev/mapper/");
+			strcat(mapper_device_full, mapper_device);
+			rc = mnt_fs_set_source(cxt->fs, mapper_device_full);
+		}
+	}
+
+done:
+	if (sym_crypt_free)
+		(*sym_crypt_free)(crypt_dev);
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	if (dl)
+		dlclose(dl);
+#endif
+	free(root_hash_binary);
+	free(mapper_device_full);
+	free(mapper_device);
+	free(hash_device);
+	free(root_hash);
+	free(root_hash_file);
+	free(root_hash_sig_file);
+	free(fec_device);
+	free(hash_sig);
+	free(key);
+	return rc;
+}
+
+int mnt_context_deferred_delete_veritydev(struct libmnt_context *cxt)
+{
+	const char *src;
+	/* If mounting failed delete immediately, otherwise setup auto cleanup for user umount */
+	uint32_t flags = mnt_context_get_status(cxt) ? CRYPT_DEACTIVATE_DEFERRED : 0;
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	void *dl = NULL;
+	int dl_flags = RTLD_LAZY | RTLD_LOCAL;
+	/* glibc extension: might help to avoid further symbols clashes */
+#ifdef RTLD_DEEPBIND
+	dl_flags |= RTLD_DEEPBIND;
+#endif
+	void (*sym_crypt_set_debug_level)(int) = NULL;
+	void (*sym_crypt_set_log_callback)(struct crypt_device *, void (*log)(int, const char *, void *), void *) = NULL;
+	int (*sym_crypt_deactivate_by_name)(struct crypt_device *, const char *, uint32_t) = NULL;
+#else
+	void (*sym_crypt_set_debug_level)(int) = &crypt_set_debug_level;
+	void (*sym_crypt_set_log_callback)(struct crypt_device *, void (*log)(int, const char *, void *), void *) = &crypt_set_log_callback;
+	int (*sym_crypt_deactivate_by_name)(struct crypt_device *, const char *, uint32_t) = &crypt_deactivate_by_name;
+#endif
+	int rc = 0;
+
+	assert(cxt);
+	assert(cxt->fs);
+
+	if (!(cxt->flags & MNT_FL_VERITYDEV_READY))
+		return 0;
+
+	src = mnt_fs_get_srcpath(cxt->fs);
+	if (!src)
+		return -EINVAL;
+
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	dl = dlopen("libcryptsetup.so.12", dl_flags);
+	if (!dl) {
+		DBG(VERITY, ul_debugobj(cxt, "veritydev specific options detected but cannot dlopen libcryptsetup"));
+		return -ENOTSUP;
+	}
+
+	/* clear errors first */
+	dlerror();
+
+	if (!rc)
+		*(void **)(&sym_crypt_set_debug_level) = get_symbol(cxt, dl, "crypt_set_debug_level", &rc);
+	if (!rc)
+		*(void **)(&sym_crypt_set_log_callback) = get_symbol(cxt, dl, "crypt_set_log_callback", &rc);
+	if (!rc)
+		*(void **)(&sym_crypt_deactivate_by_name) = get_symbol(cxt, dl, "crypt_deactivate_by_name", &rc);
+#endif
+	if (!rc) {
+		if (mnt_context_is_verbose(cxt))
+			(*sym_crypt_set_debug_level)(CRYPT_DEBUG_ALL);
+		(*sym_crypt_set_log_callback)(NULL, libcryptsetup_log, cxt);
+
+		rc = (*sym_crypt_deactivate_by_name)(NULL, src, flags);
+		if (!rc)
+			cxt->flags &= ~MNT_FL_VERITYDEV_READY;
+	}
+
+#ifdef CRYPTSETUP_VIA_DLOPEN
+	dlclose(dl);
+#endif
+	DBG(VERITY, ul_debugobj(cxt, "deleted [rc=%d]", rc));
+	return rc;
+}
+
+#else
+
+int mnt_context_setup_veritydev(struct libmnt_context *cxt __attribute__ ((__unused__)))
+{
+	return 0;
+}
+
+int mnt_context_deferred_delete_veritydev(struct libmnt_context *cxt __attribute__ ((__unused__)))
+{
+	return 0;
+}
+#endif
+
+int mnt_context_is_veritydev(struct libmnt_context *cxt)
+{
+	const char *src;
+
+	assert(cxt);
+
+	/* The mount flags have to be merged, otherwise we have to use
+	 * expensive mnt_context_get_user_mflags() instead of cxt->user_mountflags. */
+	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
+
+	if (!cxt->fs)
+		return 0;
+	src = mnt_fs_get_srcpath(cxt->fs);
+	if (!src)
+		return 0;		/* backing file not set */
+
+	if (cxt->user_mountflags & (MNT_MS_HASH_DEVICE |
+				    MNT_MS_ROOT_HASH |
+				    MNT_MS_HASH_OFFSET)) {
+#ifndef HAVE_CRYPTSETUP
+		DBG(VERITY, ul_debugobj(cxt, "veritydev specific options detected but libmount built without libcryptsetup"));
+		return -ENOTSUP;
+#else
+		DBG(VERITY, ul_debugobj(cxt, "veritydev specific options detected"));
+		return 1;
+#endif
+	}
+
+	if (!strncmp(src, "/dev/mapper/libmnt_", strlen("/dev/mapper/libmnt_"))) {
+#ifndef HAVE_CRYPTSETUP
+		DBG(VERITY, ul_debugobj(cxt, "veritydev prefix detected in source device but libmount built without libcryptsetup"));
+		return -ENOTSUP;
+#else
+		DBG(VERITY, ul_debugobj(cxt, "veritydev prefix detected in source device"));
+		return 1;
+#endif
+	}
+
+	return 0;
+}