strace/dm.c

/*
 * 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@altlinux.org>
 * Copyright (c) 2016 Eugene Syromyatnikov <evgsyr@gmail.com>
 * Copyright (c) 2016-2018 The strace developers.
 * All rights reserved.
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#include "defs.h"

#ifdef HAVE_LINUX_DM_IOCTL_H

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

# if DM_VERSION_MAJOR == 4

/* Definitions for command which have been added later */

#  ifndef DM_LIST_VERSIONS
#   define DM_LIST_VERSIONS    _IOWR(DM_IOCTL, 0x0d, struct dm_ioctl)
#  endif
#  ifndef DM_TARGET_MSG
#   define DM_TARGET_MSG       _IOWR(DM_IOCTL, 0x0e, struct dm_ioctl)
#  endif
#  ifndef DM_DEV_SET_GEOMETRY
#   define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, 0x0f, struct dm_ioctl)
#  endif
#  ifndef DM_DEV_ARM_POLL
#   define DM_DEV_ARM_POLL     _IOWR(DM_IOCTL, 0x10, struct dm_ioctl)
#  endif


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)
			PRINT_FIELD_DEV(", ", *ioc, dev);

		if (ioc->name[0])
			PRINT_FIELD_CSTRING(", ", *ioc, name);

		if (ioc->uuid[0])
			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:
			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:
			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:
			PRINT_FIELD_U(", ", *ioc, target_count);
			PRINT_FIELD_U(", ", *ioc, open_count);
			PRINT_FIELD_U(", ", *ioc, event_nr);
			break;
		}
	}
}

#  include "xlat/dm_flags.h"

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

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 i;
	uint32_t offset = ioc->data_start;
	uint32_t offset_end = 0;

	if (abbrev(tcp)) {
		if (ioc->target_count)
			tprints(", ...");

		return;
	}

	for (i = 0; i < ioc->target_count; i++) {
		tprints(", ");

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

		offset_end = offset + target_spec_size;

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

		if (i >= max_strlen) {
			tprints("...");
			break;
		}

		struct dm_target_spec s;

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

		PRINT_FIELD_U("{", s, sector_start);
		PRINT_FIELD_U(", ", s, length);

		if (exiting(tcp))
			PRINT_FIELD_D(", ", s, status);

		PRINT_FIELD_CSTRING(", ", s, target_type);

		tprints(", string=");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			     QUOTE_0_TERMINATED);
		tprints("}");

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

	return;

misplaced:
	tprints("???");
	tprints_comment("misplaced struct dm_target_spec");
}

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;

	tprints(", ");

	if (abbrev(tcp)) {
		tprints("...");
		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;

	PRINT_FIELD_U("{", s, count);

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

	tprints("}");

	return;

misplaced:
	tprints("???");
	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;
	uint32_t count;
	int rc;

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

	if (abbrev(tcp)) {
		tprints(", ...");
		return;
	}

	for (count = 0;; count++) {
		tprints(", ");

		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;

		if (count >= max_strlen) {
			tprints("...");
			break;
		}

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

		PRINT_FIELD_DEV("{", s, dev);
		tprints(", 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))
				tprintf(", event_nr=%" PRIu32, event_nr);
		}

		tprints("}");

		if (!s.next)
			break;

		offset += s.next;
	}

	return;

misplaced:
	tprints("???");
	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;
	uint32_t count;

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

	if (abbrev(tcp)) {
		tprints(", ...");
		return;
	}

	for (count = 0;; count++) {
		tprints(", ");

		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;

		if (count >= max_strlen) {
			tprints("...");
			break;
		}

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

		tprints("{name=");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			    QUOTE_0_TERMINATED);
		tprintf(", version=%" PRIu32 ".%" PRIu32 ".%" PRIu32 "}",
			s.version[0], s.version[1], s.version[2]);

		if (!s.next)
			break;

		offset += s.next;
	}

	return;

misplaced:
	tprints("???");
	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;

	tprints(", ");

	if (abbrev(tcp)) {
		tprints("...");
		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;

		PRINT_FIELD_U("{", s, sector);
		tprints(", message=");
		printstr_ex(tcp, addr + offset_end, ioc->data_size - offset_end,
			    QUOTE_0_TERMINATED);
		tprints("}");
	} else {
		tprints("???");
		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)
{
	tprints(", ");

	if (abbrev(tcp)) {
		tprints("...");
		return;
	}

	uint32_t offset = ioc->data_start;

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

static inline 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 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;

	/*
	 * device mapper code uses %d in some places and %u in another, but
	 * fields themselves are declared as __u32.
	 */
	tprintf("%s{version=%u.%u.%u",  entering(tcp) ? ", " : " => ",
		ioc->version[0], ioc->version[1], ioc->version[2]);
	/*
	 * 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;
	}

	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))
		PRINT_FIELD_U(", ", *ioc, data_start);

	dm_decode_device(code, ioc);
	dm_decode_values(tcp, code, ioc);
	dm_decode_flags(ioc);

	switch (code) {
	case DM_DEV_WAIT:
	case DM_TABLE_STATUS:
		if (entering(tcp) || syserror(tcp))
			break;
		dm_decode_dm_target_spec(tcp, arg, ioc);
		break;
	case DM_TABLE_LOAD:
		if (exiting(tcp))
			break;
		dm_decode_dm_target_spec(tcp, arg, ioc);
		break;
	case DM_TABLE_DEPS:
		if (entering(tcp) || syserror(tcp))
			break;
		dm_decode_dm_target_deps(tcp, arg, ioc);
		break;
	case DM_LIST_DEVICES:
		if (entering(tcp) || syserror(tcp))
			break;
		dm_decode_dm_name_list(tcp, arg, ioc);
		break;
	case DM_LIST_VERSIONS:
		if (entering(tcp) || syserror(tcp))
			break;
		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 (exiting(tcp))
			break;
		dm_decode_string(tcp, arg, ioc);
		break;
	}

 skip:
	tprints("}");
	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;
	}
}

# else /* !(DM_VERSION_MAJOR == 4) */

int
dm_ioctl(struct tcb *const tcp, const unsigned int code, const kernel_ulong_t arg)
{
	return RVAL_DECODED;
}

# endif /* DM_VERSION_MAJOR == 4 */
#endif /* HAVE_LINUX_DM_IOCTL_H */