regf.c

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/*
   Samba CIFS implementation
   Registry backend for REGF files
   Copyright (C) 2005-2007 Jelmer Vernooij, [e-mail]
   Copyright (C) 2006 Wilco Baan Hofman, [e-mail]

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "includes.h"
#include "system/filesys.h"
#include "system/time.h"
#include "lib/registry/tdr_regf.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "librpc/gen_ndr/winreg.h"
#include "param/param.h"
#include "lib/registry/registry.h"
#include "libcli/security/security.h"


static struct hive_operations reg_backend_regf;

/**
 * There are several places on the web where the REGF format is explained;
 *
 * TODO: Links
 */

/* TODO:
 *  - Return error codes that make more sense
 *  - Locking
 *  - do more things in-memory
 */

/*
 * Read HBIN blocks into memory
 */

struct regf_data {
	int fd;
	struct hbin_block **hbins;
	struct regf_hdr *header;
	struct smb_iconv_convenience *iconv_convenience;
};

static WERROR regf_save_hbin(struct regf_data *data);

struct regf_key_data {
	struct hive_key key;
	struct regf_data *hive;
	uint32_t offset;
	struct nk_block *nk;
};

static struct hbin_block *hbin_by_offset(const struct regf_data *data,
					 uint32_t offset, uint32_t *rel_offset)
{
	int i;

	for (i = 0; data->hbins[i]; i++) {
		if (offset >= data->hbins[i]->offset_from_first &&
			offset < data->hbins[i]->offset_from_first+
					 data->hbins[i]->offset_to_next) {
			if (rel_offset != NULL)
				*rel_offset = offset - data->hbins[i]->offset_from_first - 0x20;
			return data->hbins[i];
		}
	}

	return NULL;
}

/**
 * Validate a regf header
 * For now, do nothing, but we should check the checksum
 */
static uint32_t regf_hdr_checksum(const uint8_t *buffer)
{
	uint32_t checksum = 0, x;
	int i;

	for (i = 0; i < 0x01FB; i+= 4) {
		x = IVAL(buffer, i);
		checksum ^= x;
	}

	return checksum;
}

/**
 * Obtain the contents of a HBIN block
 */
static DATA_BLOB hbin_get(const struct regf_data *data, uint32_t offset)
{
	DATA_BLOB ret;
	struct hbin_block *hbin;
	uint32_t rel_offset;

	ret.data = NULL;
	ret.length = 0;

	hbin = hbin_by_offset(data, offset, &rel_offset);

	if (hbin == NULL) {
		DEBUG(1, ("Can't find HBIN containing 0x%04x\n", offset));
		return ret;
	}

	ret.length = IVAL(hbin->data, rel_offset);
	if (!(ret.length & 0x80000000)) {
		DEBUG(0, ("Trying to use dirty block at 0x%04x\n", offset));
		return ret;
	}

	/* remove high bit */
	ret.length = (ret.length ^ 0xffffffff) + 1;

	ret.length -= 4; /* 4 bytes for the length... */
	ret.data = hbin->data +
		(offset - hbin->offset_from_first - 0x20) + 4;

	return ret;
}

static bool hbin_get_tdr(struct regf_data *regf, uint32_t offset,
			 TALLOC_CTX *ctx, tdr_pull_fn_t pull_fn, void *p)
{
	struct tdr_pull *pull = tdr_pull_init(regf, regf->iconv_convenience);

	pull->data = hbin_get(regf, offset);
	if (!pull->data.data) {
		DEBUG(1, ("Unable to get data at 0x%04x\n", offset));
		talloc_free(pull);
		return false;
	}

	if (NT_STATUS_IS_ERR(pull_fn(pull, ctx, p))) {
		DEBUG(1, ("Error parsing record at 0x%04x using tdr\n",
			offset));
		talloc_free(pull);
		return false;
	}
	talloc_free(pull);

	return true;
}

/* Allocate some new data */
static DATA_BLOB hbin_alloc(struct regf_data *data, uint32_t size,
			    uint32_t *offset)
{
	DATA_BLOB ret;
	uint32_t rel_offset = -1; /* Relative offset ! */
	struct hbin_block *hbin = NULL;
	int i;

	*offset = 0;

	if (size == 0)
		return data_blob(NULL, 0);

	size += 4; /* Need to include int32 for the length */

	/* Allocate as a multiple of 8 */
	size = (size + 7) & ~7;

	ret.data = NULL;
	ret.length = 0;

	for (i = 0; (hbin = data->hbins[i]); i++) {
		int j;
		int32_t my_size;
		for (j = 0; j < hbin->offset_to_next-0x20; j+= my_size) {
			my_size = IVALS(hbin->data, j);

			if (my_size == 0x0) {
				DEBUG(0, ("Invalid zero-length block! File is corrupt.\n"));
				return ret;
			}

			if (my_size % 8 != 0) {
				DEBUG(0, ("Encountered non-aligned block!\n"));
			}

			if (my_size < 0) { /* Used... */
				my_size = -my_size;
			} else if (my_size == size) { /* exact match */
				rel_offset = j;
				DEBUG(4, ("Found free block of exact size %d in middle of HBIN\n",
					size));
				break;
			} else if (my_size > size) { /* data will remain */
				rel_offset = j;
				/* Split this block and mark the next block as free */
				SIVAL(hbin->data, rel_offset+size, my_size-size);
				DEBUG(4, ("Found free block of size %d (needing %d) in middle of HBIN\n",
					my_size, size));
				break;
			}
		}

		if (rel_offset != -1)
			break;
	}

	/* No space available in previous hbins,
	 * allocate new one */
	if (data->hbins[i] == NULL) {
		DEBUG(4, ("No space available in other HBINs for block of size %d, allocating new HBIN\n",
			size));
		data->hbins = talloc_realloc(data, data->hbins,
					     struct hbin_block *, i+2);
		hbin = talloc(data->hbins, struct hbin_block);
		SMB_ASSERT(hbin != NULL);

		data->hbins[i] = hbin;
		data->hbins[i+1] = NULL;

		hbin->HBIN_ID = talloc_strdup(hbin, "hbin");
		hbin->offset_from_first = (i == 0?0:data->hbins[i-1]->offset_from_first+data->hbins[i-1]->offset_to_next);
		hbin->offset_to_next = 0x1000;
		hbin->unknown[0] = 0;
		hbin->unknown[0] = 0;
		unix_to_nt_time(&hbin->last_change, time(NULL));
		hbin->block_size = hbin->offset_to_next;
		hbin->data = talloc_zero_array(hbin, uint8_t, hbin->block_size - 0x20);

		rel_offset = 0x0;
		SIVAL(hbin->data, size, hbin->block_size - size - 0x20);
	}

	/* Set size and mark as used */
	SIVAL(hbin->data, rel_offset, -size);

	ret.data = hbin->data + rel_offset + 0x4; /* Skip past length */
	ret.length = size - 0x4;
	if (offset) {
		uint32_t new_rel_offset;
		*offset = hbin->offset_from_first + rel_offset + 0x20;
		SMB_ASSERT(hbin_by_offset(data, *offset, &new_rel_offset) == hbin);
		SMB_ASSERT(new_rel_offset == rel_offset);
	}

	return ret;
}

/* Store a data blob. Return the offset at which it was stored */
static uint32_t hbin_store (struct regf_data *data, DATA_BLOB blob)
{
	uint32_t ret;
	DATA_BLOB dest = hbin_alloc(data, blob.length, &ret);

	memcpy(dest.data, blob.data, blob.length);

	return ret;
}

static uint32_t hbin_store_tdr(struct regf_data *data,
			       tdr_push_fn_t push_fn, void *p)
{
	struct tdr_push *push = tdr_push_init(data, data->iconv_convenience);
	uint32_t ret;

	if (NT_STATUS_IS_ERR(push_fn(push, p))) {
		DEBUG(0, ("Error during push\n"));
		return -1;
	}

	ret = hbin_store(data, push->data);

	talloc_free(push);

	return ret;
}


/* Free existing data */
static void hbin_free (struct regf_data *data, uint32_t offset)
{
	int32_t size;
	uint32_t rel_offset;
	int32_t next_size;
	struct hbin_block *hbin;

	SMB_ASSERT (offset > 0);

	hbin = hbin_by_offset(data, offset, &rel_offset);

	if (hbin == NULL)
		return;

	/* Get original size */
	size = IVALS(hbin->data, rel_offset);

	if (size > 0) {
		DEBUG(1, ("Trying to free already freed block at 0x%04x\n",
			offset));
		return;
	}
	/* Mark as unused */
	size = -size;

	/* If the next block is free, merge into big free block */
	if (rel_offset + size < hbin->offset_to_next) {
		next_size = IVALS(hbin->data, rel_offset+size);
		if (next_size > 0) {
			size += next_size;
		}
	}

	/* Write block size */
	SIVALS(hbin->data, rel_offset, size);
}

/**
 * Store a data blob data was already stored, but has changed in size
 * Will try to save it at the current location if possible, otherwise
 * does a free + store */
static uint32_t hbin_store_resize(struct regf_data *data,
				  uint32_t orig_offset, DATA_BLOB blob)
{
	uint32_t rel_offset;
	struct hbin_block *hbin = hbin_by_offset(data, orig_offset,
						 &rel_offset);
	int32_t my_size;
	int32_t orig_size;
	int32_t needed_size;
	int32_t possible_size;
	int i;

	SMB_ASSERT(orig_offset > 0);

	if (!hbin)
		return hbin_store(data, blob);

	/* Get original size */
	orig_size = -IVALS(hbin->data, rel_offset);

	needed_size = blob.length + 4; /* Add int32 containing length */
	needed_size = (needed_size + 7) & ~7; /* Align */

	/* Fits into current allocated block */
	if (orig_size >= needed_size) {
		memcpy(hbin->data + rel_offset + 0x4, blob.data, blob.length);
		/* If the difference in size is greater than 0x4, split the block
		 * and free/merge it */
		if (orig_size - needed_size > 0x4) {
			SIVALS(hbin->data, rel_offset, -needed_size);
			SIVALS(hbin->data, rel_offset + needed_size,
			       needed_size-orig_size);
			hbin_free(data, orig_offset + needed_size);
		}
		return orig_offset;
	}

	possible_size = orig_size;

	/* Check if it can be combined with the next few free records */
	for (i = rel_offset; i < hbin->offset_to_next - 0x20; i += my_size) {
		if (IVALS(hbin->data, i) < 0) /* Used */
			break;

		my_size = IVALS(hbin->data, i);

		if (my_size == 0x0) {
			DEBUG(0, ("Invalid zero-length block! File is corrupt.\n"));
			break;
		} else {
			possible_size += my_size;
		}

		if (possible_size >= blob.length) {
			SIVAL(hbin->data, rel_offset, -possible_size);
			memcpy(hbin->data + rel_offset + 0x4,
			       blob.data, blob.length);
			return orig_offset;
		}
	}

	hbin_free(data, orig_offset);
	return hbin_store(data, blob);
}

static uint32_t hbin_store_tdr_resize(struct regf_data *regf,
				      tdr_push_fn_t push_fn,
				      uint32_t orig_offset, void *p)
{
	struct tdr_push *push = tdr_push_init(regf, regf->iconv_convenience);
	uint32_t ret;

	if (NT_STATUS_IS_ERR(push_fn(push, p))) {
		DEBUG(0, ("Error during push\n"));
		return -1;
	}

	ret = hbin_store_resize(regf, orig_offset, push->data);

	talloc_free(push);

	return ret;
}

static uint32_t regf_create_lh_hash(const char *name)
{
	char *hash_name;
	uint32_t ret = 0;
	uint16_t i;

	hash_name = strupper_talloc(NULL, name);
	for (i = 0; *(hash_name + i) != 0; i++) {
		ret *= 37;
		ret += *(hash_name + i);
	}
	talloc_free(hash_name);
	return ret;
}

static WERROR regf_get_info(TALLOC_CTX *mem_ctx,
			    const struct hive_key *key,
			    const char **classname,
			    uint32_t *num_subkeys,
			    uint32_t *num_values,
			    NTTIME *last_mod_time,
			    uint32_t *max_subkeynamelen,
			    uint32_t *max_valnamelen,
			    uint32_t *max_valbufsize)
{
	const struct regf_key_data *private_data =
		(const struct regf_key_data *)key;

	if (num_subkeys != NULL)
		*num_subkeys = private_data->nk->num_subkeys;

	if (num_values != NULL)
		*num_values = private_data->nk->num_values;

	if (classname != NULL) {
		if (private_data->nk->clsname_offset != -1) {
			DATA_BLOB data = hbin_get(private_data->hive,
						  private_data->nk->clsname_offset);
			*classname = talloc_strndup(mem_ctx,
						    (char*)data.data,
						    private_data->nk->clsname_length);
		} else
			*classname = NULL;
	}

	/* TODO: Last mod time */

	/* TODO: max valnamelen */
	
	/* TODO: max valbufsize */

	/* TODO: max subkeynamelen */

	return WERR_OK;
}

static struct regf_key_data *regf_get_key(TALLOC_CTX *ctx,
					  struct regf_data *regf,
					  uint32_t offset)
{
	struct nk_block *nk;
	struct regf_key_data *ret;

	ret = talloc_zero(ctx, struct regf_key_data);
	ret->key.ops = &reg_backend_regf;
	ret->hive = talloc_reference(ret, regf);
	ret->offset = offset;
	nk = talloc(ret, struct nk_block);
	if (nk == NULL)
		return NULL;

	ret->nk = nk;

	if (!hbin_get_tdr(regf, offset, nk,
			  (tdr_pull_fn_t)tdr_pull_nk_block, nk)) {
		DEBUG(0, ("Unable to find HBIN data for offset %d\n", offset));
		return NULL;
	}

	if (strcmp(nk->header, "nk") != 0) {
		DEBUG(0, ("Expected nk record, got %s\n", nk->header));
		talloc_free(ret);
		return NULL;
	}

	return ret;
}


static WERROR regf_get_value(TALLOC_CTX *ctx, struct hive_key *key,
			     int idx, const char **name,
			     uint32_t *data_type, DATA_BLOB *data)
{
	const struct regf_key_data *private_data =
			(const struct regf_key_data *)key;
	struct vk_block *vk;
	struct regf_data *regf = private_data->hive;
	uint32_t vk_offset;
	DATA_BLOB tmp;

	if (idx >= private_data->nk->num_values)
		return WERR_NO_MORE_ITEMS;

	tmp = hbin_get(regf, private_data->nk->values_offset);
	if (!tmp.data) {
		DEBUG(0, ("Unable to find value list\n"));
		return WERR_GENERAL_FAILURE;
	}

	if (tmp.length < private_data->nk->num_values * 4) {
		DEBUG(1, ("Value counts mismatch\n"));
	}

	vk_offset = IVAL(tmp.data, idx * 4);

	vk = talloc(NULL, struct vk_block);
	W_ERROR_HAVE_NO_MEMORY(vk);

	if (!hbin_get_tdr(regf, vk_offset, vk,
			  (tdr_pull_fn_t)tdr_pull_vk_block, vk)) {
		DEBUG(0, ("Unable to get VK block at %d\n", vk_offset));
		talloc_free(vk);
		return WERR_GENERAL_FAILURE;
	}

	/* FIXME: name character set ?*/
	if (name != NULL)
		*name = talloc_strndup(ctx, vk->data_name, vk->name_length);

	if (data_type != NULL)