fs/ubifs/scan.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * This file is part of UBIFS.
  *
  * Copyright (C) 2006-2008 Nokia Corporation
  *
  * Authors: Adrian Hunter
  *          Artem Bityutskiy (Битюцкий Артём)
  */

 /*
  * This file implements the scan which is a general-purpose function for
  * determining what nodes are in an eraseblock. The scan is used to replay the
  * journal, to do garbage collection. for the TNC in-the-gaps method, and by
  * debugging functions.
  */

 #include "ubifs.h"

 /**
  * scan_padding_bytes - scan for padding bytes.
  * @buf: buffer to scan
  * @len: length of buffer
  *
  * This function returns the number of padding bytes on success and
  * %SCANNED_GARBAGE on failure.
  */
 static int scan_padding_bytes(void *buf, int len)
 {
 	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
 	uint8_t *p = buf;

 	dbg_scan("not a node");

 	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
 		pad_len += 1;

 	if (!pad_len || (pad_len & 7))
 		return SCANNED_GARBAGE;

 	dbg_scan("%d padding bytes", pad_len);

 	return pad_len;
 }

 /**
  * ubifs_scan_a_node - scan for a node or padding.
  * @c: UBIFS file-system description object
  * @buf: buffer to scan
  * @len: length of buffer
  * @lnum: logical eraseblock number
  * @offs: offset within the logical eraseblock
  * @quiet: print no messages
  *
  * This function returns a scanning code to indicate what was scanned.
  */
 int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
 		      int offs, int quiet)
 {
 	struct ubifs_ch *ch = buf;
 	uint32_t magic;

 	magic = le32_to_cpu(ch->magic);

 	if (magic == 0xFFFFFFFF) {
 		dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
 		return SCANNED_EMPTY_SPACE;
 	}

 	if (magic != UBIFS_NODE_MAGIC)
 		return scan_padding_bytes(buf, len);

 	if (len < UBIFS_CH_SZ)
 		return SCANNED_GARBAGE;

 	dbg_scan("scanning %s at LEB %d:%d",
 		 dbg_ntype(ch->node_type), lnum, offs);

 	if (ubifs_check_node(c, buf, len, lnum, offs, quiet, 1))
 		return SCANNED_A_CORRUPT_NODE;

 	if (ch->node_type == UBIFS_PAD_NODE) {
 		struct ubifs_pad_node *pad = buf;
 		int pad_len = le32_to_cpu(pad->pad_len);
 		int node_len = le32_to_cpu(ch->len);

 		/* Validate the padding node */
 		if (pad_len < 0 ||
 		    offs + node_len + pad_len > c->leb_size) {
 			if (!quiet) {
 				ubifs_err(c, "bad pad node at LEB %d:%d",
 					  lnum, offs);
 				ubifs_dump_node(c, pad, len);
 			}
 			return SCANNED_A_BAD_PAD_NODE;
 		}

 		/* Make the node pads to 8-byte boundary */
 		if ((node_len + pad_len) & 7) {
 			if (!quiet)
 				ubifs_err(c, "bad padding length %d - %d",
 					  offs, offs + node_len + pad_len);
 			return SCANNED_A_BAD_PAD_NODE;
 		}

 		dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
 			 lnum, offs, ALIGN(offs + node_len + pad_len, 8));

 		return node_len + pad_len;
 	}

 	return SCANNED_A_NODE;
 }

 /**
  * ubifs_start_scan - create LEB scanning information at start of scan.
  * @c: UBIFS file-system description object
  * @lnum: logical eraseblock number
  * @offs: offset to start at (usually zero)
  * @sbuf: scan buffer (must be c->leb_size)
  *
  * This function returns the scanned information on success and a negative error
  * code on failure.
  */
 struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
 					int offs, void *sbuf)
 {
 	struct ubifs_scan_leb *sleb;
 	int err;

 	dbg_scan("scan LEB %d:%d", lnum, offs);

 	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
 	if (!sleb)
 		return ERR_PTR(-ENOMEM);

 	sleb->lnum = lnum;
 	INIT_LIST_HEAD(&sleb->nodes);
 	sleb->buf = sbuf;

 	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
 	if (err && err != -EBADMSG) {
 		ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
 			  c->leb_size - offs, lnum, offs, err);
 		kfree(sleb);
 		return ERR_PTR(err);
 	}

 	/*
 	 * Note, we ignore integrity errors (EBASMSG) because all the nodes are
 	 * protected by CRC checksums.
 	 */
 	return sleb;
 }

 /**
  * ubifs_end_scan - update LEB scanning information at end of scan.
  * @c: UBIFS file-system description object
  * @sleb: scanning information
  * @lnum: logical eraseblock number
  * @offs: offset to start at (usually zero)
  */
 void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 		    int lnum, int offs)
 {
 	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
 	ubifs_assert(c, offs % c->min_io_size == 0);

 	sleb->endpt = ALIGN(offs, c->min_io_size);
 }

 /**
  * ubifs_add_snod - add a scanned node to LEB scanning information.
  * @c: UBIFS file-system description object
  * @sleb: scanning information
  * @buf: buffer containing node
  * @offs: offset of node on flash
  *
  * This function returns %0 on success and a negative error code on failure.
  */
 int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 		   void *buf, int offs)
 {
 	struct ubifs_ch *ch = buf;
 	struct ubifs_ino_node *ino = buf;
 	struct ubifs_scan_node *snod;

 	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
 	if (!snod)
 		return -ENOMEM;

 	snod->sqnum = le64_to_cpu(ch->sqnum);
 	snod->type = ch->node_type;
 	snod->offs = offs;
 	snod->len = le32_to_cpu(ch->len);
 	snod->node = buf;

 	switch (ch->node_type) {
 	case UBIFS_INO_NODE:
 	case UBIFS_DENT_NODE:
 	case UBIFS_XENT_NODE:
 	case UBIFS_DATA_NODE:
 		/*
 		 * The key is in the same place in all keyed
 		 * nodes.
 		 */
 		key_read(c, &ino->key, &snod->key);
 		break;
 	default:
 		invalid_key_init(c, &snod->key);
 		break;
 	}
 	list_add_tail(&snod->list, &sleb->nodes);
 	sleb->nodes_cnt += 1;
 	return 0;
 }

 /**
  * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
  * @c: UBIFS file-system description object
  * @lnum: LEB number of corruption
  * @offs: offset of corruption
  * @buf: buffer containing corruption
  */
 void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
 			      void *buf)
 {
 	int len;

 	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
 	len = c->leb_size - offs;
 	if (len > 8192)
 		len = 8192;
 	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
 	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
 }

 /**
  * ubifs_scan - scan a logical eraseblock.
  * @c: UBIFS file-system description object
  * @lnum: logical eraseblock number
  * @offs: offset to start at (usually zero)
  * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
  * @quiet: print no messages
  *
  * This function scans LEB number @lnum and returns complete information about
  * its contents. Returns the scanned information in case of success and,
  * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
  * of failure.
  *
  * If @quiet is non-zero, this function does not print large and scary
  * error messages and flash dumps in case of errors.
  */
 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 				  int offs, void *sbuf, int quiet)
 {
 	void *buf = sbuf + offs;
 	int err, len = c->leb_size - offs;
 	struct ubifs_scan_leb *sleb;

 	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
 	if (IS_ERR(sleb))
 		return sleb;

 	while (len >= 8) {
 		struct ubifs_ch *ch = buf;
 		int node_len, ret;

 		dbg_scan("look at LEB %d:%d (%d bytes left)",
 			 lnum, offs, len);

 		cond_resched();

 		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
 		if (ret > 0) {
 			/* Padding bytes or a valid padding node */
 			offs += ret;
 			buf += ret;
 			len -= ret;
 			continue;
 		}

 		if (ret == SCANNED_EMPTY_SPACE)
 			/* Empty space is checked later */
 			break;

 		switch (ret) {
 		case SCANNED_GARBAGE:
 			ubifs_err(c, "garbage");
 			goto corrupted;
 		case SCANNED_A_NODE:
 			break;
 		case SCANNED_A_CORRUPT_NODE:
 		case SCANNED_A_BAD_PAD_NODE:
 			ubifs_err(c, "bad node");
 			goto corrupted;
 		default:
 			ubifs_err(c, "unknown");
 			err = -EINVAL;
 			goto error;
 		}

 		err = ubifs_add_snod(c, sleb, buf, offs);
 		if (err)
 			goto error;

 		node_len = ALIGN(le32_to_cpu(ch->len), 8);
 		offs += node_len;
 		buf += node_len;
 		len -= node_len;
 	}

 	if (offs % c->min_io_size) {
 		if (!quiet)
 			ubifs_err(c, "empty space starts at non-aligned offset %d",
 				  offs);
 		goto corrupted;
 	}

 	ubifs_end_scan(c, sleb, lnum, offs);

 	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
 		if (*(uint32_t *)buf != 0xffffffff)
 			break;
 	for (; len; offs++, buf++, len--)
 		if (*(uint8_t *)buf != 0xff) {
 			if (!quiet)
 				ubifs_err(c, "corrupt empty space at LEB %d:%d",
 					  lnum, offs);
 			goto corrupted;
 		}

 	return sleb;

 corrupted:
 	if (!quiet) {
 		ubifs_scanned_corruption(c, lnum, offs, buf);
 		ubifs_err(c, "LEB %d scanning failed", lnum);
 	}
 	err = -EUCLEAN;
 	ubifs_scan_destroy(sleb);
 	return ERR_PTR(err);

 error:
 	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
 	ubifs_scan_destroy(sleb);
 	return ERR_PTR(err);
 }

 /**
  * ubifs_scan_destroy - destroy LEB scanning information.
  * @sleb: scanning information to free
  */
 void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
 {
 	struct ubifs_scan_node *node;
 	struct list_head *head;

 	head = &sleb->nodes;
 	while (!list_empty(head)) {
 		node = list_entry(head->next, struct ubifs_scan_node, list);
 		list_del(&node->list);
 		kfree(node);
 	}
 	kfree(sleb);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* This file is part of UBIFS.
	*
	* Copyright (C) 2006-2008 Nokia Corporation
	*
	* Authors: Adrian Hunter
	* Artem Bityutskiy (Битюцкий Артём)
	*/

	/*
	* This file implements the scan which is a general-purpose function for
	* determining what nodes are in an eraseblock. The scan is used to replay the
	* journal, to do garbage collection. for the TNC in-the-gaps method, and by
	* debugging functions.
	*/

	#include "ubifs.h"

	/**
	* scan_padding_bytes - scan for padding bytes.
	* @buf: buffer to scan
	* @len: length of buffer
	*
	* This function returns the number of padding bytes on success and
	* %SCANNED_GARBAGE on failure.
	*/
	static int scan_padding_bytes(void *buf, int len)
	{
	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
	uint8_t *p = buf;

	dbg_scan("not a node");

	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
	pad_len += 1;

	if (!pad_len \|\| (pad_len & 7))
	return SCANNED_GARBAGE;

	dbg_scan("%d padding bytes", pad_len);

	return pad_len;
	}

	/**
	* ubifs_scan_a_node - scan for a node or padding.
	* @c: UBIFS file-system description object
	* @buf: buffer to scan
	* @len: length of buffer
	* @lnum: logical eraseblock number
	* @offs: offset within the logical eraseblock
	* @quiet: print no messages
	*
	* This function returns a scanning code to indicate what was scanned.
	*/
	int ubifs_scan_a_node(const struct ubifs_info c, void buf, int len, int lnum,
	int offs, int quiet)
	{
	struct ubifs_ch *ch = buf;
	uint32_t magic;

	magic = le32_to_cpu(ch->magic);

	if (magic == 0xFFFFFFFF) {
	dbg_scan("hit empty space at LEB %d:%d", lnum, offs);
	return SCANNED_EMPTY_SPACE;
	}

	if (magic != UBIFS_NODE_MAGIC)
	return scan_padding_bytes(buf, len);

	if (len < UBIFS_CH_SZ)
	return SCANNED_GARBAGE;

	dbg_scan("scanning %s at LEB %d:%d",
	dbg_ntype(ch->node_type), lnum, offs);

	if (ubifs_check_node(c, buf, len, lnum, offs, quiet, 1))
	return SCANNED_A_CORRUPT_NODE;

	if (ch->node_type == UBIFS_PAD_NODE) {
	struct ubifs_pad_node *pad = buf;
	int pad_len = le32_to_cpu(pad->pad_len);
	int node_len = le32_to_cpu(ch->len);

	/* Validate the padding node */
	if (pad_len < 0 \|\|
	offs + node_len + pad_len > c->leb_size) {
	if (!quiet) {
	ubifs_err(c, "bad pad node at LEB %d:%d",
	lnum, offs);
	ubifs_dump_node(c, pad, len);
	}
	return SCANNED_A_BAD_PAD_NODE;
	}

	/* Make the node pads to 8-byte boundary */
	if ((node_len + pad_len) & 7) {
	if (!quiet)
	ubifs_err(c, "bad padding length %d - %d",
	offs, offs + node_len + pad_len);
	return SCANNED_A_BAD_PAD_NODE;
	}

	dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
	lnum, offs, ALIGN(offs + node_len + pad_len, 8));

	return node_len + pad_len;
	}

	return SCANNED_A_NODE;
	}

	/**
	* ubifs_start_scan - create LEB scanning information at start of scan.
	* @c: UBIFS file-system description object
	* @lnum: logical eraseblock number
	* @offs: offset to start at (usually zero)
	* @sbuf: scan buffer (must be c->leb_size)
	*
	* This function returns the scanned information on success and a negative error
	* code on failure.
	*/
	struct ubifs_scan_leb ubifs_start_scan(const struct ubifs_info c, int lnum,
	int offs, void *sbuf)
	{
	struct ubifs_scan_leb *sleb;
	int err;

	dbg_scan("scan LEB %d:%d", lnum, offs);

	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
	if (!sleb)
	return ERR_PTR(-ENOMEM);

	sleb->lnum = lnum;
	INIT_LIST_HEAD(&sleb->nodes);
	sleb->buf = sbuf;

	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
	if (err && err != -EBADMSG) {
	ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
	c->leb_size - offs, lnum, offs, err);
	kfree(sleb);
	return ERR_PTR(err);
	}

	/*
	* Note, we ignore integrity errors (EBASMSG) because all the nodes are
	* protected by CRC checksums.
	*/
	return sleb;
	}

	/**
	* ubifs_end_scan - update LEB scanning information at end of scan.
	* @c: UBIFS file-system description object
	* @sleb: scanning information
	* @lnum: logical eraseblock number
	* @offs: offset to start at (usually zero)
	*/
	void ubifs_end_scan(const struct ubifs_info c, struct ubifs_scan_leb sleb,
	int lnum, int offs)
	{
	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
	ubifs_assert(c, offs % c->min_io_size == 0);

	sleb->endpt = ALIGN(offs, c->min_io_size);
	}

	/**
	* ubifs_add_snod - add a scanned node to LEB scanning information.
	* @c: UBIFS file-system description object
	* @sleb: scanning information
	* @buf: buffer containing node
	* @offs: offset of node on flash
	*
	* This function returns %0 on success and a negative error code on failure.
	*/
	int ubifs_add_snod(const struct ubifs_info c, struct ubifs_scan_leb sleb,
	void *buf, int offs)
	{
	struct ubifs_ch *ch = buf;
	struct ubifs_ino_node *ino = buf;
	struct ubifs_scan_node *snod;

	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
	if (!snod)
	return -ENOMEM;

	snod->sqnum = le64_to_cpu(ch->sqnum);
	snod->type = ch->node_type;
	snod->offs = offs;
	snod->len = le32_to_cpu(ch->len);
	snod->node = buf;

	switch (ch->node_type) {
	case UBIFS_INO_NODE:
	case UBIFS_DENT_NODE:
	case UBIFS_XENT_NODE:
	case UBIFS_DATA_NODE:
	/*
	* The key is in the same place in all keyed
	* nodes.
	*/
	key_read(c, &ino->key, &snod->key);
	break;
	default:
	invalid_key_init(c, &snod->key);
	break;
	}
	list_add_tail(&snod->list, &sleb->nodes);
	sleb->nodes_cnt += 1;
	return 0;
	}

	/**
	* ubifs_scanned_corruption - print information after UBIFS scanned corruption.
	* @c: UBIFS file-system description object
	* @lnum: LEB number of corruption
	* @offs: offset of corruption
	* @buf: buffer containing corruption
	*/
	void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
	void *buf)
	{
	int len;

	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
	len = c->leb_size - offs;
	if (len > 8192)
	len = 8192;
	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
	}

	/**
	* ubifs_scan - scan a logical eraseblock.
	* @c: UBIFS file-system description object
	* @lnum: logical eraseblock number
	* @offs: offset to start at (usually zero)
	* @sbuf: scan buffer (must be of @c->leb_size bytes in size)
	* @quiet: print no messages
	*
	* This function scans LEB number @lnum and returns complete information about
	* its contents. Returns the scanned information in case of success and,
	* %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
	* of failure.
	*
	* If @quiet is non-zero, this function does not print large and scary
	* error messages and flash dumps in case of errors.
	*/
	struct ubifs_scan_leb ubifs_scan(const struct ubifs_info c, int lnum,
	int offs, void *sbuf, int quiet)
	{
	void *buf = sbuf + offs;
	int err, len = c->leb_size - offs;
	struct ubifs_scan_leb *sleb;

	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
	if (IS_ERR(sleb))
	return sleb;

	while (len >= 8) {
	struct ubifs_ch *ch = buf;
	int node_len, ret;

	dbg_scan("look at LEB %d:%d (%d bytes left)",
	lnum, offs, len);

	cond_resched();

	ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
	if (ret > 0) {
	/* Padding bytes or a valid padding node */
	offs += ret;
	buf += ret;
	len -= ret;
	continue;
	}

	if (ret == SCANNED_EMPTY_SPACE)
	/* Empty space is checked later */
	break;

	switch (ret) {
	case SCANNED_GARBAGE:
	ubifs_err(c, "garbage");
	goto corrupted;
	case SCANNED_A_NODE:
	break;
	case SCANNED_A_CORRUPT_NODE:
	case SCANNED_A_BAD_PAD_NODE:
	ubifs_err(c, "bad node");
	goto corrupted;
	default:
	ubifs_err(c, "unknown");
	err = -EINVAL;
	goto error;
	}

	err = ubifs_add_snod(c, sleb, buf, offs);
	if (err)
	goto error;

	node_len = ALIGN(le32_to_cpu(ch->len), 8);
	offs += node_len;
	buf += node_len;
	len -= node_len;
	}

	if (offs % c->min_io_size) {
	if (!quiet)
	ubifs_err(c, "empty space starts at non-aligned offset %d",
	offs);
	goto corrupted;
	}

	ubifs_end_scan(c, sleb, lnum, offs);

	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
	if ((uint32_t )buf != 0xffffffff)
	break;
	for (; len; offs++, buf++, len--)
	if ((uint8_t )buf != 0xff) {
	if (!quiet)
	ubifs_err(c, "corrupt empty space at LEB %d:%d",
	lnum, offs);
	goto corrupted;
	}

	return sleb;

	corrupted:
	if (!quiet) {
	ubifs_scanned_corruption(c, lnum, offs, buf);
	ubifs_err(c, "LEB %d scanning failed", lnum);
	}
	err = -EUCLEAN;
	ubifs_scan_destroy(sleb);
	return ERR_PTR(err);

	error:
	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
	ubifs_scan_destroy(sleb);
	return ERR_PTR(err);
	}

	/**
	* ubifs_scan_destroy - destroy LEB scanning information.
	* @sleb: scanning information to free
	*/
	void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
	{
	struct ubifs_scan_node *node;
	struct list_head *head;

	head = &sleb->nodes;
	while (!list_empty(head)) {
	node = list_entry(head->next, struct ubifs_scan_node, list);
	list_del(&node->list);
	kfree(node);
	}
	kfree(sleb);
	}