xfs: add CRC protection to remote attributes

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / xfs / xfs_attr_remote.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 *
 * 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.
 *
 * This program is distributed in the hope that it would 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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_error.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_attr_remote.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_buf_item.h"

#define ATTR_RMTVALUE_MAPSIZE   1       /* # of map entries at once */

/*
 * Each contiguous block has a header, so it is not just a simple attribute
 * length to FSB conversion.
 */
static int
xfs_attr3_rmt_blocks(
        struct xfs_mount *mp,
        int             attrlen)
{
        int             fsblocks = 0;
        int             len = attrlen;

        do {
                fsblocks++;
                len -= XFS_ATTR3_RMT_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
        } while (len > 0);

        return fsblocks;
}

static bool
xfs_attr3_rmt_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_target->bt_mount;
        struct xfs_attr3_rmt_hdr *rmt = bp->b_addr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return false;
        if (rmt->rm_magic != cpu_to_be32(XFS_ATTR3_RMT_MAGIC))
                return false;
        if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_uuid))
                return false;
        if (bp->b_bn != be64_to_cpu(rmt->rm_blkno))
                return false;
        if (be32_to_cpu(rmt->rm_offset) +
                                be32_to_cpu(rmt->rm_bytes) >= MAXPATHLEN)
                return false;
        if (rmt->rm_owner == 0)
                return false;

        return true;
}

static void
xfs_attr3_rmt_read_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
                              XFS_ATTR3_RMT_CRC_OFF) ||
            !xfs_attr3_rmt_verify(bp)) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
                xfs_buf_ioerror(bp, EFSCORRUPTED);
        }
}

static void
xfs_attr3_rmt_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;
        struct xfs_buf_log_item *bip = bp->b_fspriv;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        if (!xfs_attr3_rmt_verify(bp)) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
                xfs_buf_ioerror(bp, EFSCORRUPTED);
                return;
        }

        if (bip) {
                struct xfs_attr3_rmt_hdr *rmt = bp->b_addr;
                rmt->rm_lsn = cpu_to_be64(bip->bli_item.li_lsn);
        }
        xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
                         XFS_ATTR3_RMT_CRC_OFF);
}

const struct xfs_buf_ops xfs_attr3_rmt_buf_ops = {
        .verify_read = xfs_attr3_rmt_read_verify,
        .verify_write = xfs_attr3_rmt_write_verify,
};

static int
xfs_attr3_rmt_hdr_set(
        struct xfs_mount        *mp,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_attr3_rmt_hdr *rmt = bp->b_addr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return 0;

        rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
        rmt->rm_offset = cpu_to_be32(offset);
        rmt->rm_bytes = cpu_to_be32(size);
        uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_uuid);
        rmt->rm_owner = cpu_to_be64(ino);
        rmt->rm_blkno = cpu_to_be64(bp->b_bn);
        bp->b_ops = &xfs_attr3_rmt_buf_ops;

        return sizeof(struct xfs_attr3_rmt_hdr);
}

/*
 * Checking of the remote attribute header is split into two parts. the verifier
 * does CRC, location and bounds checking, the unpacking function checks the
 * attribute parameters and owner.
 */
static bool
xfs_attr3_rmt_hdr_ok(
        struct xfs_mount        *mp,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_attr3_rmt_hdr *rmt = bp->b_addr;

        if (offset != be32_to_cpu(rmt->rm_offset))
                return false;
        if (size != be32_to_cpu(rmt->rm_bytes))
                return false;
        if (ino != be64_to_cpu(rmt->rm_owner))
                return false;

        /* ok */
        return true;

}

/*
 * Read the value associated with an attribute from the out-of-line buffer
 * that we stored it in.
 */
int
xfs_attr_rmtval_get(
        struct xfs_da_args      *args)
{
        struct xfs_bmbt_irec    map[ATTR_RMTVALUE_MAPSIZE];
        struct xfs_mount        *mp = args->dp->i_mount;
        struct xfs_buf          *bp;
        xfs_daddr_t             dblkno;
        xfs_dablk_t             lblkno = args->rmtblkno;
        void                    *dst = args->value;
        int                     valuelen = args->valuelen;
        int                     nmap;
        int                     error;
        int                     blkcnt;
        int                     i;
        int                     offset = 0;

        trace_xfs_attr_rmtval_get(args);

        ASSERT(!(args->flags & ATTR_KERNOVAL));

        while (valuelen > 0) {
                nmap = ATTR_RMTVALUE_MAPSIZE;
                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
                                       args->rmtblkcnt, map, &nmap,
                                       XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                ASSERT(nmap >= 1);

                for (i = 0; (i < nmap) && (valuelen > 0); i++) {
                        int     byte_cnt;
                        char    *src;

                        ASSERT((map[i].br_startblock != DELAYSTARTBLOCK) &&
                               (map[i].br_startblock != HOLESTARTBLOCK));
                        dblkno = XFS_FSB_TO_DADDR(mp, map[i].br_startblock);
                        blkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
                        error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
                                                   dblkno, blkcnt, 0, &bp,
                                                   &xfs_attr3_rmt_buf_ops);
                        if (error)
                                return error;

                        byte_cnt = min_t(int, valuelen, BBTOB(bp->b_length));
                        byte_cnt = XFS_ATTR3_RMT_BUF_SPACE(mp, byte_cnt);

                        src = bp->b_addr;
                        if (xfs_sb_version_hascrc(&mp->m_sb)) {
                                if (!xfs_attr3_rmt_hdr_ok(mp, args->dp->i_ino,
                                                        offset, byte_cnt, bp)) {
                                        xfs_alert(mp,
"remote attribute header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
                                                offset, byte_cnt, args->dp->i_ino);
                                        xfs_buf_relse(bp);
                                        return EFSCORRUPTED;

                                }

                                src += sizeof(struct xfs_attr3_rmt_hdr);
                        }

                        memcpy(dst, src, byte_cnt);
                        xfs_buf_relse(bp);

                        offset += byte_cnt;
                        dst += byte_cnt;
                        valuelen -= byte_cnt;

                        lblkno += map[i].br_blockcount;
                }
        }
        ASSERT(valuelen == 0);
        return 0;
}

/*
 * Write the value associated with an attribute into the out-of-line buffer
 * that we have defined for it.
 */
int
xfs_attr_rmtval_set(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_bmbt_irec    map;
        struct xfs_buf          *bp;
        xfs_daddr_t             dblkno;
        xfs_dablk_t             lblkno;
        xfs_fileoff_t           lfileoff = 0;
        void                    *src = args->value;
        int                     blkcnt;
        int                     valuelen;
        int                     nmap;
        int                     error;
        int                     hdrcnt = 0;
        bool                    crcs = xfs_sb_version_hascrc(&mp->m_sb);
        int                     offset = 0;

        trace_xfs_attr_rmtval_set(args);

        /*
         * Find a "hole" in the attribute address space large enough for
         * us to drop the new attribute's value into. Because CRC enable
         * attributes have headers, we can't just do a straight byte to FSB
         * conversion. We calculate the worst case block count in this case
         * and we may not need that many, so we have to handle this when
         * allocating the blocks below. 
         */
        if (!crcs)
                blkcnt = XFS_B_TO_FSB(mp, args->valuelen);
        else
                blkcnt = xfs_attr3_rmt_blocks(mp, args->valuelen);

        error = xfs_bmap_first_unused(args->trans, args->dp, blkcnt, &lfileoff,
                                                   XFS_ATTR_FORK);
        if (error)
                return error;

        /* Start with the attribute data. We'll allocate the rest afterwards. */
        if (crcs)
                blkcnt = XFS_B_TO_FSB(mp, args->valuelen);

        args->rmtblkno = lblkno = (xfs_dablk_t)lfileoff;
        args->rmtblkcnt = blkcnt;

        /*
         * Roll through the "value", allocating blocks on disk as required.
         */
        while (blkcnt > 0) {
                int     committed;

                /*
                 * Allocate a single extent, up to the size of the value.
                 */
                xfs_bmap_init(args->flist, args->firstblock);
                nmap = 1;
                error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
                                  blkcnt,
                                  XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
                                  args->firstblock, args->total, &map, &nmap,
                                  args->flist);
                if (!error) {
                        error = xfs_bmap_finish(&args->trans, args->flist,
                                                &committed);
                }
                if (error) {
                        ASSERT(committed);
                        args->trans = NULL;
                        xfs_bmap_cancel(args->flist);
                        return(error);
                }

                /*
                 * bmap_finish() may have committed the last trans and started
                 * a new one.  We need the inode to be in all transactions.
                 */
                if (committed)
                        xfs_trans_ijoin(args->trans, dp, 0);

                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));
                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;
                hdrcnt++;

                /*
                 * If we have enough blocks for the attribute data, calculate
                 * how many extra blocks we need for headers. We might run
                 * through this multiple times in the case that the additional
                 * headers in the blocks needed for the data fragments spills
                 * into requiring more blocks. e.g. for 512 byte blocks, we'll
                 * spill for another block every 9 headers we require in this
                 * loop.
                 */

                if (crcs && blkcnt == 0) {
                        int total_len;

                        total_len = args->valuelen +
                                    hdrcnt * sizeof(struct xfs_attr3_rmt_hdr);
                        blkcnt = XFS_B_TO_FSB(mp, total_len);
                        blkcnt -= args->rmtblkcnt;
                        args->rmtblkcnt += blkcnt;
                }

                /*
                 * Start the next trans in the chain.
                 */
                error = xfs_trans_roll(&args->trans, dp);
                if (error)
                        return (error);
        }

        /*
         * Roll through the "value", copying the attribute value to the
         * already-allocated blocks.  Blocks are written synchronously
         * so that we can know they are all on disk before we turn off
         * the INCOMPLETE flag.
         */
        lblkno = args->rmtblkno;
        valuelen = args->valuelen;
        while (valuelen > 0) {
                int     byte_cnt;
                char    *buf;

                /*
                 * Try to remember where we decided to put the value.
                 */
                xfs_bmap_init(args->flist, args->firstblock);
                nmap = 1;
                error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
                                       args->rmtblkcnt, &map, &nmap,
                                       XFS_BMAPI_ATTRFORK);
                if (error)
                        return(error);
                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));

                dblkno = XFS_FSB_TO_DADDR(mp, map.br_startblock),
                blkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);

                bp = xfs_buf_get(mp->m_ddev_targp, dblkno, blkcnt, 0);
                if (!bp)
                        return ENOMEM;
                bp->b_ops = &xfs_attr3_rmt_buf_ops;

                byte_cnt = BBTOB(bp->b_length);
                byte_cnt = XFS_ATTR3_RMT_BUF_SPACE(mp, byte_cnt);
                if (valuelen < byte_cnt) {
                        byte_cnt = valuelen;
                }

                buf = bp->b_addr;
                buf += xfs_attr3_rmt_hdr_set(mp, dp->i_ino, offset,
                                             byte_cnt, bp);
                memcpy(buf, src, byte_cnt);

                if (byte_cnt < BBTOB(bp->b_length))
                        xfs_buf_zero(bp, byte_cnt,
                                     BBTOB(bp->b_length) - byte_cnt);

                error = xfs_bwrite(bp); /* GROT: NOTE: synchronous write */
                xfs_buf_relse(bp);
                if (error)
                        return error;

                src += byte_cnt;
                valuelen -= byte_cnt;
                offset += byte_cnt;
                hdrcnt--;

                lblkno += map.br_blockcount;
        }
        ASSERT(valuelen == 0);
        ASSERT(hdrcnt == 0);
        return 0;
}

/*
 * Remove the value associated with an attribute by deleting the
 * out-of-line buffer that it is stored on.
 */
int
xfs_attr_rmtval_remove(xfs_da_args_t *args)
{
        xfs_mount_t *mp;
        xfs_bmbt_irec_t map;
        xfs_buf_t *bp;
        xfs_daddr_t dblkno;
        xfs_dablk_t lblkno;
        int valuelen, blkcnt, nmap, error, done, committed;

        trace_xfs_attr_rmtval_remove(args);

        mp = args->dp->i_mount;

        /*
         * Roll through the "value", invalidating the attribute value's
         * blocks.
         */
        lblkno = args->rmtblkno;
        valuelen = args->rmtblkcnt;
        while (valuelen > 0) {
                /*
                 * Try to remember where we decided to put the value.
                 */
                nmap = 1;
                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
                                       args->rmtblkcnt, &map, &nmap,
                                       XFS_BMAPI_ATTRFORK);
                if (error)
                        return(error);
                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));

                dblkno = XFS_FSB_TO_DADDR(mp, map.br_startblock),
                blkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);

                /*
                 * If the "remote" value is in the cache, remove it.
                 */
                bp = xfs_incore(mp->m_ddev_targp, dblkno, blkcnt, XBF_TRYLOCK);
                if (bp) {
                        xfs_buf_stale(bp);
                        xfs_buf_relse(bp);
                        bp = NULL;
                }

                valuelen -= map.br_blockcount;

                lblkno += map.br_blockcount;
        }

        /*
         * Keep de-allocating extents until the remote-value region is gone.
         */
        lblkno = args->rmtblkno;
        blkcnt = args->rmtblkcnt;
        done = 0;
        while (!done) {
                xfs_bmap_init(args->flist, args->firstblock);
                error = xfs_bunmapi(args->trans, args->dp, lblkno, blkcnt,
                                    XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
                                    1, args->firstblock, args->flist,
                                    &done);
                if (!error) {
                        error = xfs_bmap_finish(&args->trans, args->flist,
                                                &committed);
                }
                if (error) {
                        ASSERT(committed);
                        args->trans = NULL;
                        xfs_bmap_cancel(args->flist);
                        return error;
                }

                /*
                 * bmap_finish() may have committed the last trans and started
                 * a new one.  We need the inode to be in all transactions.
                 */
                if (committed)
                        xfs_trans_ijoin(args->trans, args->dp, 0);

                /*
                 * Close out trans and start the next one in the chain.
                 */
                error = xfs_trans_roll(&args->trans, args->dp);
                if (error)
                        return (error);
        }
        return(0);
}