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![Stefan Roese](/assets/img/avatar_default.png)
The U-Boot UBIFS implementation is largely a direct copy from the current Linux version (2.6.29-rc6). As already done in the UBI version we have an "abstraction layer" to redefine or remove some OS calls (e.g. mutex_lock() ...). This makes it possible to use the original Linux code with very little changes. And by this we can better update to later Linux versions. I removed some of the Linux features that are not used in the U-Boot version (e.g. garbage-collection, write support). Signed-off-by: Stefan Roese <sr@denx.de> CC: Artem Bityutskiy <dedekind@infradead.org> CC: Adrian Hunter <ext-Adrian.Hunter@nokia.com>
317 lines
9.8 KiB
C
317 lines
9.8 KiB
C
/*
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* This file is part of UBIFS.
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*
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* Copyright (C) 2006-2008 Nokia Corporation.
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* Copyright (C) 2006, 2007 University of Szeged, Hungary
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Authors: Artem Bityutskiy (Битюцкий Артём)
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* Adrian Hunter
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* Zoltan Sogor
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*/
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/*
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* This file implements UBIFS I/O subsystem which provides various I/O-related
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* helper functions (reading/writing/checking/validating nodes) and implements
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* write-buffering support. Write buffers help to save space which otherwise
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* would have been wasted for padding to the nearest minimal I/O unit boundary.
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* Instead, data first goes to the write-buffer and is flushed when the
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* buffer is full or when it is not used for some time (by timer). This is
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* similar to the mechanism is used by JFFS2.
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*
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* Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
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* mutexes defined inside these objects. Since sometimes upper-level code
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* has to lock the write-buffer (e.g. journal space reservation code), many
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* functions related to write-buffers have "nolock" suffix which means that the
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* caller has to lock the write-buffer before calling this function.
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*
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* UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
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* aligned, UBIFS starts the next node from the aligned address, and the padded
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* bytes may contain any rubbish. In other words, UBIFS does not put padding
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* bytes in those small gaps. Common headers of nodes store real node lengths,
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* not aligned lengths. Indexing nodes also store real lengths in branches.
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*
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* UBIFS uses padding when it pads to the next min. I/O unit. In this case it
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* uses padding nodes or padding bytes, if the padding node does not fit.
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*
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* All UBIFS nodes are protected by CRC checksums and UBIFS checks all nodes
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* every time they are read from the flash media.
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*/
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#include "ubifs.h"
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/**
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* ubifs_ro_mode - switch UBIFS to read read-only mode.
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* @c: UBIFS file-system description object
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* @err: error code which is the reason of switching to R/O mode
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*/
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void ubifs_ro_mode(struct ubifs_info *c, int err)
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{
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if (!c->ro_media) {
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c->ro_media = 1;
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c->no_chk_data_crc = 0;
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ubifs_warn("switched to read-only mode, error %d", err);
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dbg_dump_stack();
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}
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}
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/**
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* ubifs_check_node - check node.
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* @c: UBIFS file-system description object
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* @buf: node to check
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* @lnum: logical eraseblock number
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* @offs: offset within the logical eraseblock
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* @quiet: print no messages
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* @must_chk_crc: indicates whether to always check the CRC
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*
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* This function checks node magic number and CRC checksum. This function also
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* validates node length to prevent UBIFS from becoming crazy when an attacker
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* feeds it a file-system image with incorrect nodes. For example, too large
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* node length in the common header could cause UBIFS to read memory outside of
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* allocated buffer when checking the CRC checksum.
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*
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* This function may skip data nodes CRC checking if @c->no_chk_data_crc is
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* true, which is controlled by corresponding UBIFS mount option. However, if
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* @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
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* checked. Similarly, if @c->always_chk_crc is true, @c->no_chk_data_crc is
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* ignored and CRC is checked.
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*
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* This function returns zero in case of success and %-EUCLEAN in case of bad
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* CRC or magic.
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*/
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int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
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int offs, int quiet, int must_chk_crc)
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{
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int err = -EINVAL, type, node_len;
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uint32_t crc, node_crc, magic;
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const struct ubifs_ch *ch = buf;
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ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
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ubifs_assert(!(offs & 7) && offs < c->leb_size);
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magic = le32_to_cpu(ch->magic);
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if (magic != UBIFS_NODE_MAGIC) {
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if (!quiet)
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ubifs_err("bad magic %#08x, expected %#08x",
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magic, UBIFS_NODE_MAGIC);
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err = -EUCLEAN;
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goto out;
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}
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type = ch->node_type;
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if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
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if (!quiet)
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ubifs_err("bad node type %d", type);
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goto out;
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}
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node_len = le32_to_cpu(ch->len);
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if (node_len + offs > c->leb_size)
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goto out_len;
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if (c->ranges[type].max_len == 0) {
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if (node_len != c->ranges[type].len)
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goto out_len;
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} else if (node_len < c->ranges[type].min_len ||
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node_len > c->ranges[type].max_len)
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goto out_len;
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if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->always_chk_crc &&
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c->no_chk_data_crc)
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return 0;
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crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
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node_crc = le32_to_cpu(ch->crc);
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if (crc != node_crc) {
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if (!quiet)
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ubifs_err("bad CRC: calculated %#08x, read %#08x",
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crc, node_crc);
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err = -EUCLEAN;
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goto out;
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}
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return 0;
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out_len:
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if (!quiet)
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ubifs_err("bad node length %d", node_len);
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out:
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if (!quiet) {
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ubifs_err("bad node at LEB %d:%d", lnum, offs);
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dbg_dump_node(c, buf);
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dbg_dump_stack();
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}
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return err;
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}
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/**
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* ubifs_pad - pad flash space.
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* @c: UBIFS file-system description object
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* @buf: buffer to put padding to
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* @pad: how many bytes to pad
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*
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* The flash media obliges us to write only in chunks of %c->min_io_size and
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* when we have to write less data we add padding node to the write-buffer and
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* pad it to the next minimal I/O unit's boundary. Padding nodes help when the
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* media is being scanned. If the amount of wasted space is not enough to fit a
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* padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
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* pattern (%UBIFS_PADDING_BYTE).
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*
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* Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
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* used.
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*/
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void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
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{
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uint32_t crc;
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ubifs_assert(pad >= 0 && !(pad & 7));
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if (pad >= UBIFS_PAD_NODE_SZ) {
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struct ubifs_ch *ch = buf;
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struct ubifs_pad_node *pad_node = buf;
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ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
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ch->node_type = UBIFS_PAD_NODE;
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ch->group_type = UBIFS_NO_NODE_GROUP;
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ch->padding[0] = ch->padding[1] = 0;
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ch->sqnum = 0;
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ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
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pad -= UBIFS_PAD_NODE_SZ;
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pad_node->pad_len = cpu_to_le32(pad);
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crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
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ch->crc = cpu_to_le32(crc);
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memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
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} else if (pad > 0)
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/* Too little space, padding node won't fit */
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memset(buf, UBIFS_PADDING_BYTE, pad);
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}
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/**
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* next_sqnum - get next sequence number.
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* @c: UBIFS file-system description object
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*/
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static unsigned long long next_sqnum(struct ubifs_info *c)
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{
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unsigned long long sqnum;
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spin_lock(&c->cnt_lock);
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sqnum = ++c->max_sqnum;
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spin_unlock(&c->cnt_lock);
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if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
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if (sqnum >= SQNUM_WATERMARK) {
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ubifs_err("sequence number overflow %llu, end of life",
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sqnum);
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ubifs_ro_mode(c, -EINVAL);
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}
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ubifs_warn("running out of sequence numbers, end of life soon");
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}
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return sqnum;
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}
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/**
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* ubifs_prepare_node - prepare node to be written to flash.
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* @c: UBIFS file-system description object
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* @node: the node to pad
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* @len: node length
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* @pad: if the buffer has to be padded
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*
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* This function prepares node at @node to be written to the media - it
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* calculates node CRC, fills the common header, and adds proper padding up to
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* the next minimum I/O unit if @pad is not zero.
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*/
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void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
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{
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uint32_t crc;
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struct ubifs_ch *ch = node;
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unsigned long long sqnum = next_sqnum(c);
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ubifs_assert(len >= UBIFS_CH_SZ);
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ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
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ch->len = cpu_to_le32(len);
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ch->group_type = UBIFS_NO_NODE_GROUP;
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ch->sqnum = cpu_to_le64(sqnum);
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ch->padding[0] = ch->padding[1] = 0;
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crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
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ch->crc = cpu_to_le32(crc);
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if (pad) {
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len = ALIGN(len, 8);
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pad = ALIGN(len, c->min_io_size) - len;
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ubifs_pad(c, node + len, pad);
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}
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}
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/**
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* ubifs_read_node - read node.
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* @c: UBIFS file-system description object
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* @buf: buffer to read to
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* @type: node type
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* @len: node length (not aligned)
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* @lnum: logical eraseblock number
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* @offs: offset within the logical eraseblock
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*
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* This function reads a node of known type and and length, checks it and
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* stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
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* and a negative error code in case of failure.
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*/
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int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
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int lnum, int offs)
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{
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int err, l;
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struct ubifs_ch *ch = buf;
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dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
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ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
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ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
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ubifs_assert(!(offs & 7) && offs < c->leb_size);
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ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
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err = ubi_read(c->ubi, lnum, buf, offs, len);
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if (err && err != -EBADMSG) {
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ubifs_err("cannot read node %d from LEB %d:%d, error %d",
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type, lnum, offs, err);
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return err;
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}
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if (type != ch->node_type) {
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ubifs_err("bad node type (%d but expected %d)",
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ch->node_type, type);
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goto out;
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}
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err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
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if (err) {
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ubifs_err("expected node type %d", type);
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return err;
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}
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l = le32_to_cpu(ch->len);
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if (l != len) {
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ubifs_err("bad node length %d, expected %d", l, len);
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goto out;
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}
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return 0;
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out:
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ubifs_err("bad node at LEB %d:%d", lnum, offs);
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dbg_dump_node(c, buf);
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dbg_dump_stack();
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return -EINVAL;
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}
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