// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_bmap.h"
#include "xfs_attr.h"
#include "xfs_attr_remote.h"
#include "xfs_trace.h"
#include "xfs_error.h"
#include "xfs_health.h"

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

/*
 * Remote Attribute Values
 * =======================
 *
 * Remote extended attribute values are conceptually simple -- they're written
 * to data blocks mapped by an inode's attribute fork, and they have an upper
 * size limit of 64k.  Setting a value does not involve the XFS log.
 *
 * However, on a v5 filesystem, maximally sized remote attr values require one
 * block more than 64k worth of space to hold both the remote attribute value
 * header (64 bytes).  On a 4k block filesystem this results in a 68k buffer;
 * on a 64k block filesystem, this would be a 128k buffer.  Note that the log
 * format can only handle a dirty buffer of XFS_MAX_BLOCKSIZE length (64k).
 * Therefore, we /must/ ensure that remote attribute value buffers never touch
 * the logging system and therefore never have a log item.
 */

/* How many bytes can be stored in a remote value buffer? */
inline unsigned int
xfs_attr3_rmt_buf_space(
        struct xfs_mount        *mp)
{
        unsigned int            blocksize = mp->m_attr_geo->blksize;

        if (xfs_has_crc(mp))
                return blocksize - sizeof(struct xfs_attr3_rmt_hdr);

        return blocksize;
}

/* Compute number of fsblocks needed to store a remote attr value */
unsigned int
xfs_attr3_rmt_blocks(
        struct xfs_mount        *mp,
        unsigned int            attrlen)
{
        /*
         * Each contiguous block has a header, so it is not just a simple
         * attribute length to FSB conversion.
         */
        if (xfs_has_crc(mp))
                return howmany(attrlen, xfs_attr3_rmt_buf_space(mp));

        return XFS_B_TO_FSB(mp, attrlen);
}

/*
 * 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 xfs_failaddr_t
xfs_attr3_rmt_hdr_ok(
        void                    *ptr,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

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

        /* ok */
        return NULL;
}

static xfs_failaddr_t
xfs_attr3_rmt_verify(
        struct xfs_mount        *mp,
        struct xfs_buf          *bp,
        void                    *ptr,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

        if (!xfs_verify_magic(bp, rmt->rm_magic))
                return __this_address;
        if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
                return __this_address;
        if (be64_to_cpu(rmt->rm_blkno) != bno)
                return __this_address;
        if (be32_to_cpu(rmt->rm_bytes) > mp->m_attr_geo->blksize - sizeof(*rmt))
                return __this_address;
        if (be32_to_cpu(rmt->rm_offset) +
                                be32_to_cpu(rmt->rm_bytes) > XFS_XATTR_SIZE_MAX)
                return __this_address;
        if (rmt->rm_owner == 0)
                return __this_address;

        return NULL;
}

static int
__xfs_attr3_rmt_read_verify(
        struct xfs_buf  *bp,
        bool            check_crc,
        xfs_failaddr_t  *failaddr)
{
        struct xfs_mount *mp = bp->b_mount;
        char            *ptr;
        unsigned int    len;
        xfs_daddr_t     bno;
        unsigned int    blksize = mp->m_attr_geo->blksize;

        /* no verification of non-crc buffers */
        if (!xfs_has_crc(mp))
                return 0;

        ptr = bp->b_addr;
        bno = xfs_buf_daddr(bp);
        len = BBTOB(bp->b_length);
        ASSERT(len >= blksize);

        while (len > 0) {
                if (check_crc &&
                    !xfs_verify_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF)) {
                        *failaddr = __this_address;
                        return -EFSBADCRC;
                }
                *failaddr = xfs_attr3_rmt_verify(mp, bp, ptr, bno);
                if (*failaddr)
                        return -EFSCORRUPTED;
                len -= blksize;
                ptr += blksize;
                bno += BTOBB(blksize);
        }

        if (len != 0) {
                *failaddr = __this_address;
                return -EFSCORRUPTED;
        }

        return 0;
}

static void
xfs_attr3_rmt_read_verify(
        struct xfs_buf  *bp)
{
        xfs_failaddr_t  fa;
        int             error;

        error = __xfs_attr3_rmt_read_verify(bp, true, &fa);
        if (error)
                xfs_verifier_error(bp, error, fa);
}

static xfs_failaddr_t
xfs_attr3_rmt_verify_struct(
        struct xfs_buf  *bp)
{
        xfs_failaddr_t  fa;
        int             error;

        error = __xfs_attr3_rmt_read_verify(bp, false, &fa);
        return error ? fa : NULL;
}

static void
xfs_attr3_rmt_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_mount;
        xfs_failaddr_t  fa;
        unsigned int    blksize = mp->m_attr_geo->blksize;
        char            *ptr;
        int             len;
        xfs_daddr_t     bno;

        /* no verification of non-crc buffers */
        if (!xfs_has_crc(mp))
                return;

        ptr = bp->b_addr;
        bno = xfs_buf_daddr(bp);
        len = BBTOB(bp->b_length);
        ASSERT(len >= blksize);

        while (len > 0) {
                struct xfs_attr3_rmt_hdr *rmt = (struct xfs_attr3_rmt_hdr *)ptr;

                fa = xfs_attr3_rmt_verify(mp, bp, ptr, bno);
                if (fa) {
                        xfs_verifier_error(bp, -EFSCORRUPTED, fa);
                        return;
                }

                /*
                 * Ensure we aren't writing bogus LSNs to disk. See
                 * xfs_attr3_rmt_hdr_set() for the explanation.
                 */
                if (rmt->rm_lsn != cpu_to_be64(NULLCOMMITLSN)) {
                        xfs_verifier_error(bp, -EFSCORRUPTED, __this_address);
                        return;
                }
                xfs_update_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF);

                len -= blksize;
                ptr += blksize;
                bno += BTOBB(blksize);
        }

        if (len != 0)
                xfs_verifier_error(bp, -EFSCORRUPTED, __this_address);
}

const struct xfs_buf_ops xfs_attr3_rmt_buf_ops = {
        .name = "xfs_attr3_rmt",
        .magic = { 0, cpu_to_be32(XFS_ATTR3_RMT_MAGIC) },
        .verify_read = xfs_attr3_rmt_read_verify,
        .verify_write = xfs_attr3_rmt_write_verify,
        .verify_struct = xfs_attr3_rmt_verify_struct,
};

STATIC int
xfs_attr3_rmt_hdr_set(
        struct xfs_mount        *mp,
        void                    *ptr,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

        if (!xfs_has_crc(mp))
                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_meta_uuid);
        rmt->rm_owner = cpu_to_be64(ino);
        rmt->rm_blkno = cpu_to_be64(bno);

        /*
         * Remote attribute blocks are written synchronously, so we don't
         * have an LSN that we can stamp in them that makes any sense to log
         * recovery. To ensure that log recovery handles overwrites of these
         * blocks sanely (i.e. once they've been freed and reallocated as some
         * other type of metadata) we need to ensure that the LSN has a value
         * that tells log recovery to ignore the LSN and overwrite the buffer
         * with whatever is in it's log. To do this, we use the magic
         * NULLCOMMITLSN to indicate that the LSN is invalid.
         */
        rmt->rm_lsn = cpu_to_be64(NULLCOMMITLSN);

        return sizeof(struct xfs_attr3_rmt_hdr);
}

/*
 * Helper functions to copy attribute data in and out of the one disk extents
 */
STATIC int
xfs_attr_rmtval_copyout(
        struct xfs_mount        *mp,
        struct xfs_buf          *bp,
        struct xfs_inode        *dp,
        xfs_ino_t               owner,
        unsigned int            *offset,
        unsigned int            *valuelen,
        uint8_t                 **dst)
{
        char                    *src = bp->b_addr;
        xfs_daddr_t             bno = xfs_buf_daddr(bp);
        unsigned int            len = BBTOB(bp->b_length);
        unsigned int            blksize = mp->m_attr_geo->blksize;

        ASSERT(len >= blksize);

        while (len > 0 && *valuelen > 0) {
                unsigned int hdr_size = 0;
                unsigned int byte_cnt = xfs_attr3_rmt_buf_space(mp);

                byte_cnt = min(*valuelen, byte_cnt);

                if (xfs_has_crc(mp)) {
                        if (xfs_attr3_rmt_hdr_ok(src, owner, *offset,
                                                  byte_cnt, bno)) {
                                xfs_alert(mp,
"remote attribute header mismatch bno/off/len/owner (0x%llx/0x%x/Ox%x/0x%llx)",
                                        bno, *offset, byte_cnt, owner);
                                xfs_dirattr_mark_sick(dp, XFS_ATTR_FORK);
                                return -EFSCORRUPTED;
                        }
                        hdr_size = sizeof(struct xfs_attr3_rmt_hdr);
                }

                memcpy(*dst, src + hdr_size, byte_cnt);

                /* roll buffer forwards */
                len -= blksize;
                src += blksize;
                bno += BTOBB(blksize);

                /* roll attribute data forwards */
                *valuelen -= byte_cnt;
                *dst += byte_cnt;
                *offset += byte_cnt;
        }
        return 0;
}

STATIC void
xfs_attr_rmtval_copyin(
        struct xfs_mount *mp,
        struct xfs_buf  *bp,
        xfs_ino_t       ino,
        unsigned int    *offset,
        unsigned int    *valuelen,
        uint8_t         **src)
{
        char            *dst = bp->b_addr;
        xfs_daddr_t     bno = xfs_buf_daddr(bp);
        unsigned int    len = BBTOB(bp->b_length);
        unsigned int    blksize = mp->m_attr_geo->blksize;

        ASSERT(len >= blksize);

        while (len > 0 && *valuelen > 0) {
                unsigned int hdr_size;
                unsigned int byte_cnt = xfs_attr3_rmt_buf_space(mp);

                byte_cnt = min(*valuelen, byte_cnt);
                hdr_size = xfs_attr3_rmt_hdr_set(mp, dst, ino, *offset,
                                                 byte_cnt, bno);

                memcpy(dst + hdr_size, *src, byte_cnt);

                /*
                 * If this is the last block, zero the remainder of it.
                 * Check that we are actually the last block, too.
                 */
                if (byte_cnt + hdr_size < blksize) {
                        ASSERT(*valuelen - byte_cnt == 0);
                        ASSERT(len == blksize);
                        memset(dst + hdr_size + byte_cnt, 0,
                                        blksize - hdr_size - byte_cnt);
                }

                /* roll buffer forwards */
                len -= blksize;
                dst += blksize;
                bno += BTOBB(blksize);

                /* roll attribute data forwards */
                *valuelen -= byte_cnt;
                *src += byte_cnt;
                *offset += byte_cnt;
        }
}

/*
 * Read the value associated with an attribute from the out-of-line buffer
 * that we stored it in.
 *
 * Returns 0 on successful retrieval, otherwise an error.
 */
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_dablk_t             lblkno = args->rmtblkno;
        uint8_t                 *dst = args->value;
        unsigned int            valuelen;
        int                     nmap;
        int                     error;
        unsigned int            blkcnt = args->rmtblkcnt;
        int                     i;
        unsigned int            offset = 0;

        trace_xfs_attr_rmtval_get(args);

        ASSERT(args->valuelen != 0);
        ASSERT(args->rmtvaluelen == args->valuelen);

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

                for (i = 0; (i < nmap) && (valuelen > 0); i++) {
                        xfs_daddr_t     dblkno;
                        int             dblkcnt;

                        ASSERT((map[i].br_startblock != DELAYSTARTBLOCK) &&
                               (map[i].br_startblock != HOLESTARTBLOCK));
                        dblkno = XFS_FSB_TO_DADDR(mp, map[i].br_startblock);
                        dblkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
                        error = xfs_buf_read(mp->m_ddev_targp, dblkno, dblkcnt,
                                        0, &bp, &xfs_attr3_rmt_buf_ops);
                        if (xfs_metadata_is_sick(error))
                                xfs_dirattr_mark_sick(args->dp, XFS_ATTR_FORK);
                        /*
                         * ENODATA from disk implies a disk medium failure;
                         * ENODATA for xattrs means attribute not found, so
                         * disambiguate that here.
                         */
                        if (error == -ENODATA)
                                error = -EIO;
                        if (error)
                                return error;

                        error = xfs_attr_rmtval_copyout(mp, bp, args->dp,
                                        args->owner, &offset, &valuelen, &dst);
                        xfs_buf_relse(bp);
                        if (error)
                                return error;

                        /* roll attribute extent map forwards */
                        lblkno += map[i].br_blockcount;
                        blkcnt -= map[i].br_blockcount;
                }
        }
        ASSERT(valuelen == 0);
        return 0;
}

/*
 * Find a "hole" in the attribute address space large enough for us to drop the
 * new attributes value into
 */
int
xfs_attr_rmt_find_hole(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        int                     error;
        unsigned int            blkcnt;
        xfs_fileoff_t           lfileoff = 0;

        /*
         * Because CRC enable attributes have headers, we can't just do a
         * straight byte to FSB conversion and have to take the header space
         * into account.
         */
        blkcnt = xfs_attr3_rmt_blocks(mp, args->rmtvaluelen);
        error = xfs_bmap_first_unused(args->trans, args->dp, blkcnt, &lfileoff,
                                                   XFS_ATTR_FORK);
        if (error)
                return error;

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

        return 0;
}

int
xfs_attr_rmtval_set_value(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_bmbt_irec    map;
        xfs_dablk_t             lblkno;
        uint8_t                 *src = args->value;
        unsigned int            blkcnt;
        unsigned int            valuelen;
        int                     nmap;
        int                     error;
        unsigned int            offset = 0;

        /*
         * 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;
        blkcnt = args->rmtblkcnt;
        valuelen = args->rmtvaluelen;
        while (valuelen > 0) {
                struct xfs_buf  *bp;
                xfs_daddr_t     dblkno;
                int             dblkcnt;

                ASSERT(blkcnt > 0);

                nmap = 1;
                error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
                                       blkcnt, &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),
                dblkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);

                error = xfs_buf_get(mp->m_ddev_targp, dblkno, dblkcnt, &bp);
                if (error)
                        return error;
                bp->b_ops = &xfs_attr3_rmt_buf_ops;

                xfs_attr_rmtval_copyin(mp, bp, args->owner, &offset, &valuelen,
                                &src);

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


                /* roll attribute extent map forwards */
                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;
        }
        ASSERT(valuelen == 0);
        return 0;
}

/* Mark stale any incore buffers for the remote value. */
int
xfs_attr_rmtval_stale(
        struct xfs_inode        *ip,
        struct xfs_bmbt_irec    *map,
        xfs_buf_flags_t         incore_flags)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_buf          *bp;
        int                     error;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);

        if (XFS_IS_CORRUPT(mp, map->br_startblock == DELAYSTARTBLOCK) ||
            XFS_IS_CORRUPT(mp, map->br_startblock == HOLESTARTBLOCK)) {
                xfs_bmap_mark_sick(ip, XFS_ATTR_FORK);
                return -EFSCORRUPTED;
        }

        error = xfs_buf_incore(mp->m_ddev_targp,
                        XFS_FSB_TO_DADDR(mp, map->br_startblock),
                        XFS_FSB_TO_BB(mp, map->br_blockcount),
                        incore_flags, &bp);
        if (error) {
                if (error == -ENOENT)
                        return 0;
                return error;
        }

        xfs_buf_stale(bp);
        xfs_buf_relse(bp);
        return 0;
}

/*
 * Find a hole for the attr and store it in the delayed attr context.  This
 * initializes the context to roll through allocating an attr extent for a
 * delayed attr operation
 */
int
xfs_attr_rmtval_find_space(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_bmbt_irec            *map = &attr->xattri_map;
        int                             error;

        attr->xattri_lblkno = 0;
        attr->xattri_blkcnt = 0;
        args->rmtblkcnt = 0;
        args->rmtblkno = 0;
        memset(map, 0, sizeof(struct xfs_bmbt_irec));

        error = xfs_attr_rmt_find_hole(args);
        if (error)
                return error;

        attr->xattri_blkcnt = args->rmtblkcnt;
        attr->xattri_lblkno = args->rmtblkno;

        return 0;
}

/*
 * Write one block of the value associated with an attribute into the
 * out-of-line buffer that we have defined for it. This is similar to a subset
 * of xfs_attr_rmtval_set, but records the current block to the delayed attr
 * context, and leaves transaction handling to the caller.
 */
int
xfs_attr_rmtval_set_blk(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        struct xfs_inode                *dp = args->dp;
        struct xfs_bmbt_irec            *map = &attr->xattri_map;
        int nmap;
        int error;

        nmap = 1;
        error = xfs_bmapi_write(args->trans, dp,
                        (xfs_fileoff_t)attr->xattri_lblkno,
                        attr->xattri_blkcnt, XFS_BMAPI_ATTRFORK, args->total,
                        map, &nmap);
        if (error)
                return error;

        ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
               (map->br_startblock != HOLESTARTBLOCK));

        /* roll attribute extent map forwards */
        attr->xattri_lblkno += map->br_blockcount;
        attr->xattri_blkcnt -= map->br_blockcount;

        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_invalidate(
        struct xfs_da_args      *args)
{
        xfs_dablk_t             lblkno;
        unsigned int            blkcnt;
        int                     error;

        /*
         * Roll through the "value", invalidating the attribute value's blocks.
         */
        lblkno = args->rmtblkno;
        blkcnt = args->rmtblkcnt;
        while (blkcnt > 0) {
                struct xfs_bmbt_irec    map;
                int                     nmap;

                /*
                 * Try to remember where we decided to put the value.
                 */
                nmap = 1;
                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
                                       blkcnt, &map, &nmap, XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                if (XFS_IS_CORRUPT(args->dp->i_mount, nmap != 1)) {
                        xfs_bmap_mark_sick(args->dp, XFS_ATTR_FORK);
                        return -EFSCORRUPTED;
                }
                error = xfs_attr_rmtval_stale(args->dp, &map, XBF_TRYLOCK);
                if (error)
                        return error;

                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;
        }
        return 0;
}

/*
 * Remove the value associated with an attribute by deleting the out-of-line
 * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
 * transaction and re-call the function.  Callers should keep calling this
 * routine until it returns something other than -EAGAIN.
 */
int
xfs_attr_rmtval_remove(
        struct xfs_attr_intent          *attr)
{
        struct xfs_da_args              *args = attr->xattri_da_args;
        int                             error, done;

        /*
         * Unmap value blocks for this attr.
         */
        error = xfs_bunmapi(args->trans, args->dp, args->rmtblkno,
                            args->rmtblkcnt, XFS_BMAPI_ATTRFORK, 1, &done);
        if (error)
                return error;

        /*
         * We don't need an explicit state here to pick up where we left off. We
         * can figure it out using the !done return code. The actual value of
         * attr->xattri_dela_state may be some value reminiscent of the calling
         * function, but it's value is irrelevant with in the context of this
         * function. Once we are done here, the next state is set as needed by
         * the parent
         */
        if (!done) {
                trace_xfs_attr_rmtval_remove_return(attr->xattri_dela_state,
                                                    args->dp);
                return -EAGAIN;
        }

        args->rmtblkno = 0;
        args->rmtblkcnt = 0;
        return 0;
}