// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * Copyright (c) 2012-2013 Red Hat, Inc.
 * All rights reserved.
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_shared.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_error.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_log.h"
#include "xfs_symlink_remote.h"
#include "xfs_bit.h"
#include "xfs_bmap.h"
#include "xfs_health.h"

/*
 * Each contiguous block has a header, so it is not just a simple pathlen
 * to FSB conversion.
 */
int
xfs_symlink_blocks(
        struct xfs_mount *mp,
        int             pathlen)
{
        int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);

        return (pathlen + buflen - 1) / buflen;
}

int
xfs_symlink_hdr_set(
        struct xfs_mount        *mp,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

        if (!xfs_has_crc(mp))
                return 0;

        memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
        dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
        dsl->sl_offset = cpu_to_be32(offset);
        dsl->sl_bytes = cpu_to_be32(size);
        uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
        dsl->sl_owner = cpu_to_be64(ino);
        dsl->sl_blkno = cpu_to_be64(xfs_buf_daddr(bp));
        bp->b_ops = &xfs_symlink_buf_ops;

        return sizeof(struct xfs_dsymlink_hdr);
}

/*
 * Checking of the symlink header is split into two parts. the verifier does
 * CRC, location and bounds checking, the unpacking function checks the path
 * parameters and owner.
 */
bool
xfs_symlink_hdr_ok(
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        struct xfs_buf          *bp)
{
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

        if (offset != be32_to_cpu(dsl->sl_offset))
                return false;
        if (size != be32_to_cpu(dsl->sl_bytes))
                return false;
        if (ino != be64_to_cpu(dsl->sl_owner))
                return false;

        /* ok */
        return true;
}

static xfs_failaddr_t
xfs_symlink_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_mount;
        struct xfs_dsymlink_hdr *dsl = bp->b_addr;

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

        if (!xfs_verify_magic(bp, dsl->sl_magic))
                return __this_address;
        if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
                return __this_address;
        if (xfs_buf_daddr(bp) != be64_to_cpu(dsl->sl_blkno))
                return __this_address;
        if (be32_to_cpu(dsl->sl_offset) +
                                be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
                return __this_address;
        if (dsl->sl_owner == 0)
                return __this_address;
        if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
                return __this_address;

        return NULL;
}

static void
xfs_symlink_read_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_mount;
        xfs_failaddr_t  fa;

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

        if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
                xfs_verifier_error(bp, -EFSBADCRC, __this_address);
        else {
                fa = xfs_symlink_verify(bp);
                if (fa)
                        xfs_verifier_error(bp, -EFSCORRUPTED, fa);
        }
}

static void
xfs_symlink_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_mount;
        struct xfs_buf_log_item *bip = bp->b_log_item;
        xfs_failaddr_t          fa;

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

        fa = xfs_symlink_verify(bp);
        if (fa) {
                xfs_verifier_error(bp, -EFSCORRUPTED, fa);
                return;
        }

        if (bip) {
                struct xfs_dsymlink_hdr *dsl = bp->b_addr;
                dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
        }
        xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
}

const struct xfs_buf_ops xfs_symlink_buf_ops = {
        .name = "xfs_symlink",
        .magic = { 0, cpu_to_be32(XFS_SYMLINK_MAGIC) },
        .verify_read = xfs_symlink_read_verify,
        .verify_write = xfs_symlink_write_verify,
        .verify_struct = xfs_symlink_verify,
};

void
xfs_symlink_local_to_remote(
        struct xfs_trans        *tp,
        struct xfs_buf          *bp,
        struct xfs_inode        *ip,
        struct xfs_ifork        *ifp,
        void                    *priv)
{
        struct xfs_mount        *mp = ip->i_mount;
        char                    *buf;

        xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);

        if (!xfs_has_crc(mp)) {
                bp->b_ops = NULL;
                memcpy(bp->b_addr, ifp->if_data, ifp->if_bytes);
                xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
                return;
        }

        /*
         * As this symlink fits in an inode literal area, it must also fit in
         * the smallest buffer the filesystem supports.
         */
        ASSERT(BBTOB(bp->b_length) >=
                        ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));

        bp->b_ops = &xfs_symlink_buf_ops;

        buf = bp->b_addr;
        buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
        memcpy(buf, ifp->if_data, ifp->if_bytes);
        xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
                                        ifp->if_bytes - 1);
}

/*
 * Verify the in-memory consistency of an inline symlink data fork. This
 * does not do on-disk format checks.
 */
xfs_failaddr_t
xfs_symlink_shortform_verify(
        void                    *sfp,
        int64_t                 size)
{
        char                    *endp = sfp + size;

        /*
         * Zero length symlinks should never occur in memory as they are
         * never allowed to exist on disk.
         */
        if (!size)
                return __this_address;

        /* No negative sizes or overly long symlink targets. */
        if (size < 0 || size > XFS_SYMLINK_MAXLEN)
                return __this_address;

        /* No NULLs in the target either. */
        if (memchr(sfp, 0, size - 1))
                return __this_address;

        /* We /did/ null-terminate the buffer, right? */
        if (*endp != 0)
                return __this_address;
        return NULL;
}

/* Read a remote symlink target into the buffer. */
int
xfs_symlink_remote_read(
        struct xfs_inode        *ip,
        char                    *link)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
        struct xfs_buf          *bp;
        xfs_daddr_t             d;
        char                    *cur_chunk;
        int                     pathlen = ip->i_disk_size;
        int                     nmaps = XFS_SYMLINK_MAPS;
        int                     byte_cnt;
        int                     n;
        int                     error = 0;
        int                     fsblocks = 0;
        int                     offset;

        xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);

        fsblocks = xfs_symlink_blocks(mp, pathlen);
        error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
        if (error)
                goto out;

        offset = 0;
        for (n = 0; n < nmaps; n++) {
                d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
                byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);

                error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
                                &bp, &xfs_symlink_buf_ops);
                if (xfs_metadata_is_sick(error))
                        xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
                if (error)
                        return error;
                byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
                if (pathlen < byte_cnt)
                        byte_cnt = pathlen;

                cur_chunk = bp->b_addr;
                if (xfs_has_crc(mp)) {
                        if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
                                                        byte_cnt, bp)) {
                                xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
                                error = -EFSCORRUPTED;
                                xfs_alert(mp,
"symlink header does not match required off/len/owner (0x%x/0x%x,0x%llx)",
                                        offset, byte_cnt, ip->i_ino);
                                xfs_buf_relse(bp);
                                goto out;

                        }

                        cur_chunk += sizeof(struct xfs_dsymlink_hdr);
                }

                memcpy(link + offset, cur_chunk, byte_cnt);

                pathlen -= byte_cnt;
                offset += byte_cnt;

                xfs_buf_relse(bp);
        }
        ASSERT(pathlen == 0);

        link[ip->i_disk_size] = '\0';
        error = 0;

 out:
        return error;
}

/* Write the symlink target into the inode. */
int
xfs_symlink_write_target(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_ino_t               owner,
        const char              *target_path,
        int                     pathlen,
        xfs_fsblock_t           fs_blocks,
        uint                    resblks)
{
        struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
        struct xfs_mount        *mp = tp->t_mountp;
        const char              *cur_chunk;
        struct xfs_buf          *bp;
        xfs_daddr_t             d;
        int                     byte_cnt;
        int                     nmaps;
        int                     offset = 0;
        int                     n;
        int                     error;

        /*
         * If the symlink will fit into the inode, write it inline.
         */
        if (pathlen <= xfs_inode_data_fork_size(ip)) {
                xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);

                ip->i_disk_size = pathlen;
                ip->i_df.if_format = XFS_DINODE_FMT_LOCAL;
                xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
                return 0;
        }

        nmaps = XFS_SYMLINK_MAPS;
        error = xfs_bmapi_write(tp, ip, 0, fs_blocks, XFS_BMAPI_METADATA,
                        resblks, mval, &nmaps);
        if (error)
                return error;

        ip->i_disk_size = pathlen;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        cur_chunk = target_path;
        offset = 0;
        for (n = 0; n < nmaps; n++) {
                char    *buf;

                d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
                byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
                error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
                                BTOBB(byte_cnt), 0, &bp);
                if (error)
                        return error;
                bp->b_ops = &xfs_symlink_buf_ops;

                byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
                byte_cnt = min(byte_cnt, pathlen);

                buf = bp->b_addr;
                buf += xfs_symlink_hdr_set(mp, owner, offset, byte_cnt, bp);

                memcpy(buf, cur_chunk, byte_cnt);

                cur_chunk += byte_cnt;
                pathlen -= byte_cnt;
                offset += byte_cnt;

                xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
                xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
                                                (char *)bp->b_addr);
        }
        ASSERT(pathlen == 0);
        return 0;
}

/* Remove all the blocks from a symlink and invalidate buffers. */
int
xfs_symlink_remote_truncate(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip)
{
        struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
        struct xfs_mount        *mp = tp->t_mountp;
        struct xfs_buf          *bp;
        int                     nmaps = XFS_SYMLINK_MAPS;
        int                     done = 0;
        int                     i;
        int                     error;

        /* Read mappings and invalidate buffers. */
        error = xfs_bmapi_read(ip, 0, XFS_MAX_FILEOFF, mval, &nmaps, 0);
        if (error)
                return error;

        for (i = 0; i < nmaps; i++) {
                if (!xfs_bmap_is_real_extent(&mval[i]))
                        break;

                error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
                                XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
                                XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
                                &bp);
                if (error)
                        return error;

                xfs_trans_binval(tp, bp);
        }

        /* Unmap the remote blocks. */
        error = xfs_bunmapi(tp, ip, 0, XFS_MAX_FILEOFF, 0, nmaps, &done);
        if (error)
                return error;
        if (!done) {
                ASSERT(done);
                xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
                return -EFSCORRUPTED;
        }

        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        return 0;
}