githubmirror/strace

src/dm.c
635 строк14 KB
Dmitry V. Levin
Update copyright headers
05 авг 2025, 11:00
05 авг 2025, 11:007db24b3
/*
 * Support for decoding of DM_* ioctl commands.
 *
 * Copyright (c) 2016 Mikulas Patocka <mpatocka@redhat.com>
 * Copyright (c) 2016 Masatake Yamato <yamato@redhat.com>
 * Copyright (c) 2016 Dmitry V. Levin <ldv@strace.io>
 * Copyright (c) 2016 Eugene Syromyatnikov <evgsyr@gmail.com>
 * Copyright (c) 2016-2025 The strace developers.
 * All rights reserved.
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#include "defs.h"
#include <linux/dm-ioctl.h>
#include <linux/ioctl.h>

/* Defined in lvm2/libdm/ioctl/libdm-iface.c file.  */
#define DM_EXISTS_FLAG 0x00000004

#include "xlat/dm_flags.h"

static void
dm_decode_device(const unsigned int code, const struct dm_ioctl *ioc)
{
	switch (code) {
	case DM_REMOVE_ALL:
	case DM_LIST_DEVICES:
	case DM_LIST_VERSIONS:
		break;
	default:
		if (ioc->dev) {
			tprint_struct_next();
			PRINT_FIELD_DEV(*ioc, dev);
		}

		if (ioc->name[0]) {
			tprint_struct_next();
			PRINT_FIELD_CSTRING(*ioc, name);
		}

		if (ioc->uuid[0]) {
			tprint_struct_next();
			PRINT_FIELD_CSTRING(*ioc, uuid);
		}

		break;
	}
}

static void
dm_decode_values(struct tcb *tcp, const unsigned int code,
		 const struct dm_ioctl *ioc)
{
	if (entering(tcp)) {
		switch (code) {
		case DM_TABLE_LOAD:
			tprint_struct_next();
			PRINT_FIELD_U(*ioc, target_count);
			break;
		case DM_DEV_SUSPEND:
			if (ioc->flags & DM_SUSPEND_FLAG)
				break;
			ATTRIBUTE_FALLTHROUGH;
		case DM_DEV_RENAME:
		case DM_DEV_REMOVE:
		case DM_DEV_WAIT:
			tprint_struct_next();
			PRINT_FIELD_U(*ioc, event_nr);
			break;
		}
	} else if (!syserror(tcp)) {
		switch (code) {
		case DM_DEV_CREATE:
		case DM_DEV_RENAME:
		case DM_DEV_SUSPEND:
		case DM_DEV_STATUS:
		case DM_DEV_WAIT:
		case DM_TABLE_LOAD:
		case DM_TABLE_CLEAR:
		case DM_TABLE_DEPS:
		case DM_TABLE_STATUS:
		case DM_TARGET_MSG:
			tprint_struct_next();
			PRINT_FIELD_U(*ioc, target_count);
			tprint_struct_next();
			PRINT_FIELD_U(*ioc, open_count);
			tprint_struct_next();
			PRINT_FIELD_U(*ioc, event_nr);
			break;
		}
	}
}

static void
dm_decode_flags(const struct dm_ioctl *ioc)
{
	tprint_struct_next();
	PRINT_FIELD_FLAGS(*ioc, flags, dm_flags, "DM_???");
}

static bool
dm_ioctl_has_params(const unsigned int code)
{
	switch (code) {
	case DM_VERSION:
	case DM_REMOVE_ALL:
	case DM_DEV_CREATE:
	case DM_DEV_REMOVE:
	case DM_DEV_SUSPEND:
	case DM_DEV_STATUS:
	case DM_TABLE_CLEAR:
	case DM_DEV_ARM_POLL:
		return false;
	}

	return true;
}

static bool
dm_decode_header(struct tcb *const tcp, const unsigned int code,
		 const kernel_ulong_t arg, const struct dm_ioctl *const ioc)
{
	bool rc = false;

	tprint_struct_begin();
	/*
	 * device mapper code uses %d in some places and %u in another, but
	 * fields themselves are declared as __u32.
	 */
	PRINT_FIELD_U_ARRAY(*ioc, version);
	/*
	 * if we use a different version of ABI, do not attempt to decode
	 * ioctl fields
	 */
	if (ioc->version[0] != DM_VERSION_MAJOR) {
		tprints_comment("unsupported device mapper ABI version");
		goto skip;
	}

	tprint_struct_next();
	PRINT_FIELD_U(*ioc, data_size);

	if (ioc->data_size < offsetof(struct dm_ioctl, data)) {
		tprints_comment("data_size too small");
		goto skip;
	}

	if (dm_ioctl_has_params(code)) {
		tprint_struct_next();
		PRINT_FIELD_U(*ioc, data_start);
	}

	dm_decode_device(code, ioc);
	dm_decode_values(tcp, code, ioc);
	dm_decode_flags(ioc);
	rc = true;

 skip:
	tprint_struct_end();
	return rc;
}

static void
dm_decode_dm_target_spec(struct tcb *const tcp, const kernel_ulong_t addr,
			 const struct dm_ioctl *const ioc)
{
	static const uint32_t target_spec_size =
		sizeof(struct dm_target_spec);
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = 0;

	if (abbrev(tcp)) {
		if (ioc->target_count) {
			tprint_array_next();
			tprint_more_data_follows();
		}

		return;
	}

	for (uint32_t i = 0; i < ioc->target_count; ++i) {
		tprint_array_next();

		if (i && offset <= offset_end)
			goto misplaced;

		offset_end = offset + target_spec_size;

		if (offset_end <= offset || offset_end > ioc->data_size)
			goto misplaced;

		/* i starts with 0, hence i + 1 */
		if (sequence_truncation_needed(tcp, i + 1)) {
			tprint_more_data_follows();
			break;
		}

		struct dm_target_spec s;

		if (umove_or_printaddr(tcp, addr + offset, &s))
			break;

		tprint_struct_begin();
		PRINT_FIELD_U(s, sector_start);
		tprint_struct_next();
		PRINT_FIELD_U(s, length);

		if (exiting(tcp)) {
			tprint_struct_next();
			PRINT_FIELD_D(s, status);
		}

		tprint_struct_next();
		PRINT_FIELD_CSTRING(s, target_type);

		tprint_struct_next();
		tprints_field_name("string");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			     QUOTE_0_TERMINATED);
		tprint_struct_end();

		if (entering(tcp))
			offset += s.next;
		else
			offset = ioc->data_start + s.next;
	}

	return;

misplaced:
	tprint_unavailable();
	tprints_comment("misplaced struct dm_target_spec");
}

static bool
dm_print_dev(struct tcb *tcp, void *dev_ptr, size_t dev_size, void *dummy)
{
	uint64_t *dev = (uint64_t *) dev_ptr;

	print_dev_t(*dev);

	return 1;
}

static void
dm_decode_dm_target_deps(struct tcb *const tcp, const kernel_ulong_t addr,
			 const struct dm_ioctl *const ioc)
{
	if (ioc->data_start == ioc->data_size)
		return;

	tprint_array_next();

	if (abbrev(tcp)) {
		tprint_more_data_follows();
		return;
	}

	static const uint32_t target_deps_dev_offs =
		offsetof(struct dm_target_deps, dev);
	uint64_t dev_buf;
	struct dm_target_deps s;
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = offset + target_deps_dev_offs;
	uint32_t space;

	if (offset_end <= offset || offset_end > ioc->data_size)
		goto misplaced;

	if (umove_or_printaddr(tcp, addr + offset, &s))
		return;

	space = (ioc->data_size - offset_end) / sizeof(dev_buf);

	if (s.count > space)
		goto misplaced;

	tprint_struct_begin();
	PRINT_FIELD_U(s, count);

	tprint_struct_next();
	tprints_field_name("deps");
	print_array(tcp, addr + offset_end, s.count, &dev_buf, sizeof(dev_buf),
		    tfetch_mem, dm_print_dev, NULL);

	tprint_struct_end();

	return;

misplaced:
	tprint_unavailable();
	tprints_comment("misplaced struct dm_target_deps");
}

static void
dm_decode_dm_name_list(struct tcb *const tcp, const kernel_ulong_t addr,
		       const struct dm_ioctl *const ioc)
{
	static const uint32_t name_list_name_offs =
		offsetof(struct dm_name_list, name);
	struct dm_name_list s;
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = 0;
	int rc;

	if (ioc->data_start == ioc->data_size)
		return;

	if (abbrev(tcp)) {
		tprint_array_next();
		tprint_more_data_follows();
		return;
	}

	for (uint32_t count = 0;; ++count) {
		tprint_array_next();

		if (count && offset <= offset_end)
			goto misplaced;

		offset_end = offset + name_list_name_offs;

		if (offset_end <= offset || offset_end > ioc->data_size)
			goto misplaced;

		/* count starts with 0, hence count + 1 */
		if (sequence_truncation_needed(tcp, count + 1)) {
			tprint_more_data_follows();
			break;
		}

		if (umove_or_printaddr(tcp, addr + offset, &s))
			break;

		tprint_struct_begin();
		PRINT_FIELD_DEV(s, dev);
		tprint_struct_next();
		tprints_field_name("name");
		rc = printstr_ex(tcp, addr + offset_end,
				 ioc->data_size - offset_end,
				 QUOTE_0_TERMINATED);

		/*
		 * In Linux v4.13-rc1~137^2~13 it has been decided to cram in
		 * one more undocumented field after the device name, as if the
		 * format decoding was not twisted enough already. So, we have
		 * to check "next" now, and if it _looks like_ that there is
		 * a space for one additional integer, let's print it. As if the
		 * perversity with "name string going further than pointer to
		 * the next one" wasn't enough. Moreover, the calculation was
		 * broken for m32 on 64-bit kernels until v4.14-rc4~20^2~3, and
		 * we have no ability to detect kernel bit-ness (on x86, at
		 * least), so refrain from printing it for the DM versions below
		 * 4.37 (the original version was also aligned differently than
		 * now even on 64 bit).
		 */

		if ((rc > 0) && ioc->version[1] >= 37) {
			kernel_ulong_t event_addr =
				(addr + offset_end + rc + 7) & ~7;
			uint32_t event_nr;

			if ((event_addr + sizeof(event_nr)) <=
			    (addr + offset + s.next) &&
			    !umove(tcp, event_addr, &event_nr)) {
				tprint_struct_next();
				tprints_field_name("event_nr");
				PRINT_VAL_U(event_nr);
			}
		}

		tprint_struct_end();

		if (!s.next)
			break;

		offset += s.next;
	}

	return;

misplaced:
	tprint_unavailable();
	tprints_comment("misplaced struct dm_name_list");
}

static void
dm_decode_dm_target_versions(struct tcb *const tcp, const kernel_ulong_t addr,
			     const struct dm_ioctl *const ioc)
{
	static const uint32_t target_vers_name_offs =
		offsetof(struct dm_target_versions, name);
	struct dm_target_versions s;
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = 0;

	if (ioc->data_start == ioc->data_size)
		return;

	if (abbrev(tcp)) {
		tprint_array_next();
		tprint_more_data_follows();
		return;
	}

	for (uint32_t count = 0;; ++count) {
		tprint_array_next();

		if (count && offset <= offset_end)
			goto misplaced;

		offset_end = offset + target_vers_name_offs;

		if (offset_end <= offset || offset_end > ioc->data_size)
			goto misplaced;

		/* count starts with 0, hence count + 1 */
		if (sequence_truncation_needed(tcp, count + 1)) {
			tprint_more_data_follows();
			break;
		}

		if (umove_or_printaddr(tcp, addr + offset, &s))
			break;

		tprint_struct_begin();
		tprints_field_name("name");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			    QUOTE_0_TERMINATED);
		tprint_struct_next();
		PRINT_FIELD_U_ARRAY(s, version);
		tprint_struct_end();

		if (!s.next)
			break;

		offset += s.next;
	}

	return;

misplaced:
	tprint_unavailable();
	tprints_comment("misplaced struct dm_target_versions");
}

static void
dm_decode_dm_target_msg(struct tcb *const tcp, const kernel_ulong_t addr,
			const struct dm_ioctl *const ioc)
{
	if (ioc->data_start == ioc->data_size)
		return;

	tprint_array_next();

	if (abbrev(tcp)) {
		tprint_more_data_follows();
		return;
	}

	static const uint32_t target_msg_message_offs =
		offsetof(struct dm_target_msg, message);
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = offset + target_msg_message_offs;

	if (offset_end > offset && offset_end <= ioc->data_size) {
		struct dm_target_msg s;

		if (umove_or_printaddr(tcp, addr + offset, &s))
			return;

		tprint_struct_begin();
		PRINT_FIELD_U(s, sector);
		tprint_struct_next();
		tprints_field_name("message");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			    QUOTE_0_TERMINATED);
		tprint_struct_end();
	} else {
		tprint_unavailable();
		tprints_comment("misplaced struct dm_target_msg");
	}
}

static void
dm_decode_string(struct tcb *const tcp, const kernel_ulong_t addr,
		 const struct dm_ioctl *const ioc)
{
	tprint_array_next();

	if (abbrev(tcp)) {
		tprint_more_data_follows();
		return;
	}

	uint32_t offset = ioc->data_start;

	if (offset <= ioc->data_size) {
		tprint_struct_begin();
		tprints_field_name("string");
		printstr_ex(tcp, addr + offset, ioc->data_size - offset,
			    QUOTE_0_TERMINATED);
		tprint_struct_end();
	} else {
		tprint_unavailable();
		tprints_comment("misplaced string");
	}
}

static void
dm_decode_payload(struct tcb *const tcp, const unsigned int code,
		  const kernel_ulong_t arg, const struct dm_ioctl *const ioc)
{
	switch (code) {
	case DM_DEV_WAIT:
	case DM_TABLE_STATUS:
		if (exiting(tcp) && !syserror(tcp))
			dm_decode_dm_target_spec(tcp, arg, ioc);
		break;
	case DM_TABLE_LOAD:
		if (entering(tcp))
			dm_decode_dm_target_spec(tcp, arg, ioc);
		break;
	case DM_TABLE_DEPS:
		if (exiting(tcp) && !syserror(tcp))
			dm_decode_dm_target_deps(tcp, arg, ioc);
		break;
	case DM_LIST_DEVICES:
		if (exiting(tcp) && !syserror(tcp))
			dm_decode_dm_name_list(tcp, arg, ioc);
		break;
	case DM_LIST_VERSIONS:
		if (exiting(tcp) && !syserror(tcp))
			dm_decode_dm_target_versions(tcp, arg, ioc);
		break;
	case DM_TARGET_MSG:
		if (entering(tcp))
			dm_decode_dm_target_msg(tcp, arg, ioc);
		else if (!syserror(tcp) && ioc->flags & DM_DATA_OUT_FLAG)
			dm_decode_string(tcp, arg, ioc);
		break;
	case DM_DEV_RENAME:
	case DM_DEV_SET_GEOMETRY:
		if (entering(tcp))
			dm_decode_string(tcp, arg, ioc);
		break;
	}
}

static int
dm_known_ioctl(struct tcb *const tcp, const unsigned int code,
	       const kernel_ulong_t arg)
{
	struct dm_ioctl *ioc = NULL;
	struct dm_ioctl *entering_ioc = NULL;
	bool ioc_changed = false;

	if (entering(tcp)) {
		ioc = malloc(sizeof(*ioc));
		if (!ioc)
			return 0;
	} else {
		ioc = alloca(sizeof(*ioc));
	}

	if ((umoven(tcp, arg, offsetof(struct dm_ioctl, data), ioc) < 0) ||
	    (ioc->data_size < offsetof(struct dm_ioctl, data_size))) {
		if (entering(tcp))
			free(ioc);
		return 0;
	}
	if (entering(tcp))
		set_tcb_priv_data(tcp, ioc, free);
	else {
		entering_ioc = get_tcb_priv_data(tcp);

		/*
		 * retrieve_status, __dev_status called only in case of success,
		 * so it looks like there's no need to check open_count,
		 * event_nr, target_count, dev fields for change (they are
		 * printed only in case of absence of errors).
		 */
		if (!entering_ioc ||
		    (ioc->version[0] != entering_ioc->version[0]) ||
		    (ioc->version[1] != entering_ioc->version[1]) ||
		    (ioc->version[2] != entering_ioc->version[2]) ||
		    (ioc->data_size != entering_ioc->data_size) ||
		    (ioc->data_start != entering_ioc->data_start) ||
		    (ioc->flags != entering_ioc->flags))
			ioc_changed = true;
	}

	if (exiting(tcp) && syserror(tcp) && !ioc_changed)
		return RVAL_IOCTL_DECODED;

	if (entering(tcp))
		tprints_arg_next_name("argp");
	else
		tprint_value_changed();

	tprint_array_begin();
	if (dm_decode_header(tcp, code, arg, ioc))
		dm_decode_payload(tcp, code, arg, ioc);
	tprint_array_end();

	return entering(tcp) ? 0 : RVAL_IOCTL_DECODED;
}

int
dm_ioctl(struct tcb *const tcp, const unsigned int code, const kernel_ulong_t arg)
{
	switch (code) {
	case DM_VERSION:
	case DM_REMOVE_ALL:
	case DM_LIST_DEVICES:
	case DM_DEV_CREATE:
	case DM_DEV_REMOVE:
	case DM_DEV_RENAME:
	case DM_DEV_SUSPEND:
	case DM_DEV_STATUS:
	case DM_DEV_WAIT:
	case DM_TABLE_LOAD:
	case DM_TABLE_CLEAR:
	case DM_TABLE_DEPS:
	case DM_TABLE_STATUS:
	case DM_LIST_VERSIONS:
	case DM_TARGET_MSG:
	case DM_DEV_SET_GEOMETRY:
	case DM_DEV_ARM_POLL:
		return dm_known_ioctl(tcp, code, arg);
	default:
		return RVAL_DECODED;
	}
}