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author | Stefan Roese <sr@denx.de> | 2009-03-19 15:35:05 +0100 |
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committer | Wolfgang Denk <wd@denx.de> | 2009-03-20 22:39:15 +0100 |
commit | 9eefe2a2b37a838558e3d213a9f5519503d0c180 (patch) | |
tree | cd6ce359f020615d685d353fc3a20e7e07ac05fc /fs/ubifs/io.c | |
parent | b1b4e89a0f3b75854c39a62cae41bad56d210adf (diff) | |
download | u-boot-imx-9eefe2a2b37a838558e3d213a9f5519503d0c180.zip u-boot-imx-9eefe2a2b37a838558e3d213a9f5519503d0c180.tar.gz u-boot-imx-9eefe2a2b37a838558e3d213a9f5519503d0c180.tar.bz2 |
UBIFS: Implement read-only UBIFS support in U-Boot
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>
Diffstat (limited to 'fs/ubifs/io.c')
-rw-r--r-- | fs/ubifs/io.c | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c new file mode 100644 index 0000000..aae5c65 --- /dev/null +++ b/fs/ubifs/io.c @@ -0,0 +1,316 @@ +/* + * This file is part of UBIFS. + * + * Copyright (C) 2006-2008 Nokia Corporation. + * Copyright (C) 2006, 2007 University of Szeged, Hungary + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * 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, write to the Free Software Foundation, Inc., 51 + * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + * + * Authors: Artem Bityutskiy (Битюцкий Артём) + * Adrian Hunter + * Zoltan Sogor + */ + +/* + * This file implements UBIFS I/O subsystem which provides various I/O-related + * helper functions (reading/writing/checking/validating nodes) and implements + * write-buffering support. Write buffers help to save space which otherwise + * would have been wasted for padding to the nearest minimal I/O unit boundary. + * Instead, data first goes to the write-buffer and is flushed when the + * buffer is full or when it is not used for some time (by timer). This is + * similar to the mechanism is used by JFFS2. + * + * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by + * mutexes defined inside these objects. Since sometimes upper-level code + * has to lock the write-buffer (e.g. journal space reservation code), many + * functions related to write-buffers have "nolock" suffix which means that the + * caller has to lock the write-buffer before calling this function. + * + * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not + * aligned, UBIFS starts the next node from the aligned address, and the padded + * bytes may contain any rubbish. In other words, UBIFS does not put padding + * bytes in those small gaps. Common headers of nodes store real node lengths, + * not aligned lengths. Indexing nodes also store real lengths in branches. + * + * UBIFS uses padding when it pads to the next min. I/O unit. In this case it + * uses padding nodes or padding bytes, if the padding node does not fit. + * + * All UBIFS nodes are protected by CRC checksums and UBIFS checks all nodes + * every time they are read from the flash media. + */ + +#include "ubifs.h" + +/** + * ubifs_ro_mode - switch UBIFS to read read-only mode. + * @c: UBIFS file-system description object + * @err: error code which is the reason of switching to R/O mode + */ +void ubifs_ro_mode(struct ubifs_info *c, int err) +{ + if (!c->ro_media) { + c->ro_media = 1; + c->no_chk_data_crc = 0; + ubifs_warn("switched to read-only mode, error %d", err); + dbg_dump_stack(); + } +} + +/** + * ubifs_check_node - check node. + * @c: UBIFS file-system description object + * @buf: node to check + * @lnum: logical eraseblock number + * @offs: offset within the logical eraseblock + * @quiet: print no messages + * @must_chk_crc: indicates whether to always check the CRC + * + * This function checks node magic number and CRC checksum. This function also + * validates node length to prevent UBIFS from becoming crazy when an attacker + * feeds it a file-system image with incorrect nodes. For example, too large + * node length in the common header could cause UBIFS to read memory outside of + * allocated buffer when checking the CRC checksum. + * + * This function may skip data nodes CRC checking if @c->no_chk_data_crc is + * true, which is controlled by corresponding UBIFS mount option. However, if + * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is + * checked. Similarly, if @c->always_chk_crc is true, @c->no_chk_data_crc is + * ignored and CRC is checked. + * + * This function returns zero in case of success and %-EUCLEAN in case of bad + * CRC or magic. + */ +int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum, + int offs, int quiet, int must_chk_crc) +{ + int err = -EINVAL, type, node_len; + uint32_t crc, node_crc, magic; + const struct ubifs_ch *ch = buf; + + ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0); + ubifs_assert(!(offs & 7) && offs < c->leb_size); + + magic = le32_to_cpu(ch->magic); + if (magic != UBIFS_NODE_MAGIC) { + if (!quiet) + ubifs_err("bad magic %#08x, expected %#08x", + magic, UBIFS_NODE_MAGIC); + err = -EUCLEAN; + goto out; + } + + type = ch->node_type; + if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) { + if (!quiet) + ubifs_err("bad node type %d", type); + goto out; + } + + node_len = le32_to_cpu(ch->len); + if (node_len + offs > c->leb_size) + goto out_len; + + if (c->ranges[type].max_len == 0) { + if (node_len != c->ranges[type].len) + goto out_len; + } else if (node_len < c->ranges[type].min_len || + node_len > c->ranges[type].max_len) + goto out_len; + + if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->always_chk_crc && + c->no_chk_data_crc) + return 0; + + crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8); + node_crc = le32_to_cpu(ch->crc); + if (crc != node_crc) { + if (!quiet) + ubifs_err("bad CRC: calculated %#08x, read %#08x", + crc, node_crc); + err = -EUCLEAN; + goto out; + } + + return 0; + +out_len: + if (!quiet) + ubifs_err("bad node length %d", node_len); +out: + if (!quiet) { + ubifs_err("bad node at LEB %d:%d", lnum, offs); + dbg_dump_node(c, buf); + dbg_dump_stack(); + } + return err; +} + +/** + * ubifs_pad - pad flash space. + * @c: UBIFS file-system description object + * @buf: buffer to put padding to + * @pad: how many bytes to pad + * + * The flash media obliges us to write only in chunks of %c->min_io_size and + * when we have to write less data we add padding node to the write-buffer and + * pad it to the next minimal I/O unit's boundary. Padding nodes help when the + * media is being scanned. If the amount of wasted space is not enough to fit a + * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes + * pattern (%UBIFS_PADDING_BYTE). + * + * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is + * used. + */ +void ubifs_pad(const struct ubifs_info *c, void *buf, int pad) +{ + uint32_t crc; + + ubifs_assert(pad >= 0 && !(pad & 7)); + + if (pad >= UBIFS_PAD_NODE_SZ) { + struct ubifs_ch *ch = buf; + struct ubifs_pad_node *pad_node = buf; + + ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC); + ch->node_type = UBIFS_PAD_NODE; + ch->group_type = UBIFS_NO_NODE_GROUP; + ch->padding[0] = ch->padding[1] = 0; + ch->sqnum = 0; + ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ); + pad -= UBIFS_PAD_NODE_SZ; + pad_node->pad_len = cpu_to_le32(pad); + crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8); + ch->crc = cpu_to_le32(crc); + memset(buf + UBIFS_PAD_NODE_SZ, 0, pad); + } else if (pad > 0) + /* Too little space, padding node won't fit */ + memset(buf, UBIFS_PADDING_BYTE, pad); +} + +/** + * next_sqnum - get next sequence number. + * @c: UBIFS file-system description object + */ +static unsigned long long next_sqnum(struct ubifs_info *c) +{ + unsigned long long sqnum; + + spin_lock(&c->cnt_lock); + sqnum = ++c->max_sqnum; + spin_unlock(&c->cnt_lock); + + if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) { + if (sqnum >= SQNUM_WATERMARK) { + ubifs_err("sequence number overflow %llu, end of life", + sqnum); + ubifs_ro_mode(c, -EINVAL); + } + ubifs_warn("running out of sequence numbers, end of life soon"); + } + + return sqnum; +} + +/** + * ubifs_prepare_node - prepare node to be written to flash. + * @c: UBIFS file-system description object + * @node: the node to pad + * @len: node length + * @pad: if the buffer has to be padded + * + * This function prepares node at @node to be written to the media - it + * calculates node CRC, fills the common header, and adds proper padding up to + * the next minimum I/O unit if @pad is not zero. + */ +void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad) +{ + uint32_t crc; + struct ubifs_ch *ch = node; + unsigned long long sqnum = next_sqnum(c); + + ubifs_assert(len >= UBIFS_CH_SZ); + + ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC); + ch->len = cpu_to_le32(len); + ch->group_type = UBIFS_NO_NODE_GROUP; + ch->sqnum = cpu_to_le64(sqnum); + ch->padding[0] = ch->padding[1] = 0; + crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8); + ch->crc = cpu_to_le32(crc); + + if (pad) { + len = ALIGN(len, 8); + pad = ALIGN(len, c->min_io_size) - len; + ubifs_pad(c, node + len, pad); + } +} + +/** + * ubifs_read_node - read node. + * @c: UBIFS file-system description object + * @buf: buffer to read to + * @type: node type + * @len: node length (not aligned) + * @lnum: logical eraseblock number + * @offs: offset within the logical eraseblock + * + * This function reads a node of known type and and length, checks it and + * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched + * and a negative error code in case of failure. + */ +int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len, + int lnum, int offs) +{ + int err, l; + struct ubifs_ch *ch = buf; + + dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len); + ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0); + ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size); + ubifs_assert(!(offs & 7) && offs < c->leb_size); + ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT); + + err = ubi_read(c->ubi, lnum, buf, offs, len); + if (err && err != -EBADMSG) { + ubifs_err("cannot read node %d from LEB %d:%d, error %d", + type, lnum, offs, err); + return err; + } + + if (type != ch->node_type) { + ubifs_err("bad node type (%d but expected %d)", + ch->node_type, type); + goto out; + } + + err = ubifs_check_node(c, buf, lnum, offs, 0, 0); + if (err) { + ubifs_err("expected node type %d", type); + return err; + } + + l = le32_to_cpu(ch->len); + if (l != len) { + ubifs_err("bad node length %d, expected %d", l, len); + goto out; + } + + return 0; + +out: + ubifs_err("bad node at LEB %d:%d", lnum, offs); + dbg_dump_node(c, buf); + dbg_dump_stack(); + return -EINVAL; +} |