/*
 * Copyright (C) 2017 Oracle.  All Rights Reserved.
 *
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_btree.h"
#include "xfs_bit.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_dir2.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/dabtree.h"
#include "scrub/trace.h"

#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>

/* Set us up to scrub an inode's extended attributes. */
int
xfs_scrub_setup_xattr(
        struct xfs_scrub_context        *sc,
        struct xfs_inode                *ip)
{
        size_t                          sz;

        /*
         * Allocate the buffer without the inode lock held.  We need enough
         * space to read every xattr value in the file or enough space to
         * hold three copies of the xattr free space bitmap.  (Not both at
         * the same time.)
         */
        sz = max_t(size_t, XATTR_SIZE_MAX, 3 * sizeof(long) *
                        BITS_TO_LONGS(sc->mp->m_attr_geo->blksize));
        sc->buf = kmem_zalloc_large(sz, KM_SLEEP);
        if (!sc->buf)
                return -ENOMEM;

        return xfs_scrub_setup_inode_contents(sc, ip, 0);
}

/* Extended Attributes */

struct xfs_scrub_xattr {
        struct xfs_attr_list_context    context;
        struct xfs_scrub_context        *sc;
};

/*
 * Check that an extended attribute key can be looked up by hash.
 *
 * We use the XFS attribute list iterator (i.e. xfs_attr_list_int_ilocked)
 * to call this function for every attribute key in an inode.  Once
 * we're here, we load the attribute value to see if any errors happen,
 * or if we get more or less data than we expected.
 */
static void
xfs_scrub_xattr_listent(
        struct xfs_attr_list_context    *context,
        int                             flags,
        unsigned char                   *name,
        int                             namelen,
        int                             valuelen)
{
        struct xfs_scrub_xattr          *sx;
        struct xfs_da_args              args = { NULL };
        int                             error = 0;

        sx = container_of(context, struct xfs_scrub_xattr, context);

        if (flags & XFS_ATTR_INCOMPLETE) {
                /* Incomplete attr key, just mark the inode for preening. */
                xfs_scrub_ino_set_preen(sx->sc, context->dp->i_ino);
                return;
        }

        args.flags = ATTR_KERNOTIME;
        if (flags & XFS_ATTR_ROOT)
                args.flags |= ATTR_ROOT;
        else if (flags & XFS_ATTR_SECURE)
                args.flags |= ATTR_SECURE;
        args.geo = context->dp->i_mount->m_attr_geo;
        args.whichfork = XFS_ATTR_FORK;
        args.dp = context->dp;
        args.name = name;
        args.namelen = namelen;
        args.hashval = xfs_da_hashname(args.name, args.namelen);
        args.trans = context->tp;
        args.value = sx->sc->buf;
        args.valuelen = XATTR_SIZE_MAX;

        error = xfs_attr_get_ilocked(context->dp, &args);
        if (error == -EEXIST)
                error = 0;
        if (!xfs_scrub_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
                        &error))
                goto fail_xref;
        if (args.valuelen != valuelen)
                xfs_scrub_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
                                             args.blkno);

fail_xref:
        return;
}

/*
 * Mark a range [start, start+len) in this map.  Returns true if the
 * region was free, and false if there's a conflict or a problem.
 *
 * Within a char, the lowest bit of the char represents the byte with
 * the smallest address
 */
STATIC bool
xfs_scrub_xattr_set_map(
        struct xfs_scrub_context        *sc,
        unsigned long                   *map,
        unsigned int                    start,
        unsigned int                    len)
{
        unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
        bool                            ret = true;

        if (start >= mapsize)
                return false;
        if (start + len > mapsize) {
                len = mapsize - start;
                ret = false;
        }

        if (find_next_bit(map, mapsize, start) < start + len)
                ret = false;
        bitmap_set(map, start, len);

        return ret;
}

/*
 * Check the leaf freemap from the usage bitmap.  Returns false if the
 * attr freemap has problems or points to used space.
 */
STATIC bool
xfs_scrub_xattr_check_freemap(
        struct xfs_scrub_context        *sc,
        unsigned long                   *map,
        struct xfs_attr3_icleaf_hdr     *leafhdr)
{
        unsigned long                   *freemap;
        unsigned long                   *dstmap;
        unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
        int                             i;

        /* Construct bitmap of freemap contents. */
        freemap = (unsigned long *)sc->buf + BITS_TO_LONGS(mapsize);
        bitmap_zero(freemap, mapsize);
        for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
                if (!xfs_scrub_xattr_set_map(sc, freemap,
                                leafhdr->freemap[i].base,
                                leafhdr->freemap[i].size))
                        return false;
        }

        /* Look for bits that are set in freemap and are marked in use. */
        dstmap = freemap + BITS_TO_LONGS(mapsize);
        return bitmap_and(dstmap, freemap, map, mapsize) == 0;
}

/*
 * Check this leaf entry's relations to everything else.
 * Returns the number of bytes used for the name/value data.
 */
STATIC void
xfs_scrub_xattr_entry(
        struct xfs_scrub_da_btree       *ds,
        int                             level,
        char                            *buf_end,
        struct xfs_attr_leafblock       *leaf,
        struct xfs_attr3_icleaf_hdr     *leafhdr,
        unsigned long                   *usedmap,
        struct xfs_attr_leaf_entry      *ent,
        int                             idx,
        unsigned int                    *usedbytes,
        __u32                           *last_hashval)
{
        struct xfs_mount                *mp = ds->state->mp;
        char                            *name_end;
        struct xfs_attr_leaf_name_local *lentry;
        struct xfs_attr_leaf_name_remote *rentry;
        unsigned int                    nameidx;
        unsigned int                    namesize;

        if (ent->pad2 != 0)
                xfs_scrub_da_set_corrupt(ds, level);

        /* Hash values in order? */
        if (be32_to_cpu(ent->hashval) < *last_hashval)
                xfs_scrub_da_set_corrupt(ds, level);
        *last_hashval = be32_to_cpu(ent->hashval);

        nameidx = be16_to_cpu(ent->nameidx);
        if (nameidx < leafhdr->firstused ||
            nameidx >= mp->m_attr_geo->blksize) {
                xfs_scrub_da_set_corrupt(ds, level);
                return;
        }

        /* Check the name information. */
        if (ent->flags & XFS_ATTR_LOCAL) {
                lentry = xfs_attr3_leaf_name_local(leaf, idx);
                namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
                                be16_to_cpu(lentry->valuelen));
                name_end = (char *)lentry + namesize;
                if (lentry->namelen == 0)
                        xfs_scrub_da_set_corrupt(ds, level);
        } else {
                rentry = xfs_attr3_leaf_name_remote(leaf, idx);
                namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
                name_end = (char *)rentry + namesize;
                if (rentry->namelen == 0 || rentry->valueblk == 0)
                        xfs_scrub_da_set_corrupt(ds, level);
        }
        if (name_end > buf_end)
                xfs_scrub_da_set_corrupt(ds, level);

        if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, nameidx, namesize))
                xfs_scrub_da_set_corrupt(ds, level);
        if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
                *usedbytes += namesize;
}

/* Scrub an attribute leaf. */
STATIC int
xfs_scrub_xattr_block(
        struct xfs_scrub_da_btree       *ds,
        int                             level)
{
        struct xfs_attr3_icleaf_hdr     leafhdr;
        struct xfs_mount                *mp = ds->state->mp;
        struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
        struct xfs_buf                  *bp = blk->bp;
        xfs_dablk_t                     *last_checked = ds->private;
        struct xfs_attr_leafblock       *leaf = bp->b_addr;
        struct xfs_attr_leaf_entry      *ent;
        struct xfs_attr_leaf_entry      *entries;
        unsigned long                   *usedmap = ds->sc->buf;
        char                            *buf_end;
        size_t                          off;
        __u32                           last_hashval = 0;
        unsigned int                    usedbytes = 0;
        unsigned int                    hdrsize;
        int                             i;

        if (*last_checked == blk->blkno)
                return 0;
        *last_checked = blk->blkno;
        bitmap_zero(usedmap, mp->m_attr_geo->blksize);

        /* Check all the padding. */
        if (xfs_sb_version_hascrc(&ds->sc->mp->m_sb)) {
                struct xfs_attr3_leafblock      *leaf = bp->b_addr;

                if (leaf->hdr.pad1 != 0 || leaf->hdr.pad2 != 0 ||
                    leaf->hdr.info.hdr.pad != 0)
                        xfs_scrub_da_set_corrupt(ds, level);
        } else {
                if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
                        xfs_scrub_da_set_corrupt(ds, level);
        }

        /* Check the leaf header */
        xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
        hdrsize = xfs_attr3_leaf_hdr_size(leaf);

        if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
                xfs_scrub_da_set_corrupt(ds, level);
        if (leafhdr.firstused > mp->m_attr_geo->blksize)
                xfs_scrub_da_set_corrupt(ds, level);
        if (leafhdr.firstused < hdrsize)
                xfs_scrub_da_set_corrupt(ds, level);
        if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, 0, hdrsize))
                xfs_scrub_da_set_corrupt(ds, level);

        if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        entries = xfs_attr3_leaf_entryp(leaf);
        if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
                xfs_scrub_da_set_corrupt(ds, level);

        buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
        for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
                /* Mark the leaf entry itself. */
                off = (char *)ent - (char *)leaf;
                if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, off,
                                sizeof(xfs_attr_leaf_entry_t))) {
                        xfs_scrub_da_set_corrupt(ds, level);
                        goto out;
                }

                /* Check the entry and nameval. */
                xfs_scrub_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
                                usedmap, ent, i, &usedbytes, &last_hashval);

                if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                        goto out;
        }

        if (!xfs_scrub_xattr_check_freemap(ds->sc, usedmap, &leafhdr))
                xfs_scrub_da_set_corrupt(ds, level);

        if (leafhdr.usedbytes != usedbytes)
                xfs_scrub_da_set_corrupt(ds, level);

out:
        return 0;
}

/* Scrub a attribute btree record. */
STATIC int
xfs_scrub_xattr_rec(
        struct xfs_scrub_da_btree       *ds,
        int                             level,
        void                            *rec)
{
        struct xfs_mount                *mp = ds->state->mp;
        struct xfs_attr_leaf_entry      *ent = rec;
        struct xfs_da_state_blk         *blk;
        struct xfs_attr_leaf_name_local *lentry;
        struct xfs_attr_leaf_name_remote        *rentry;
        struct xfs_buf                  *bp;
        xfs_dahash_t                    calc_hash;
        xfs_dahash_t                    hash;
        int                             nameidx;
        int                             hdrsize;
        unsigned int                    badflags;
        int                             error;

        blk = &ds->state->path.blk[level];

        /* Check the whole block, if necessary. */
        error = xfs_scrub_xattr_block(ds, level);
        if (error)
                goto out;
        if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        /* Check the hash of the entry. */
        error = xfs_scrub_da_btree_hash(ds, level, &ent->hashval);
        if (error)
                goto out;

        /* Find the attr entry's location. */
        bp = blk->bp;
        hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
        nameidx = be16_to_cpu(ent->nameidx);
        if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
                xfs_scrub_da_set_corrupt(ds, level);
                goto out;
        }

        /* Retrieve the entry and check it. */
        hash = be32_to_cpu(ent->hashval);
        badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
                        XFS_ATTR_INCOMPLETE);
        if ((ent->flags & badflags) != 0)
                xfs_scrub_da_set_corrupt(ds, level);
        if (ent->flags & XFS_ATTR_LOCAL) {
                lentry = (struct xfs_attr_leaf_name_local *)
                                (((char *)bp->b_addr) + nameidx);
                if (lentry->namelen <= 0) {
                        xfs_scrub_da_set_corrupt(ds, level);
                        goto out;
                }
                calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
        } else {
                rentry = (struct xfs_attr_leaf_name_remote *)
                                (((char *)bp->b_addr) + nameidx);
                if (rentry->namelen <= 0) {
                        xfs_scrub_da_set_corrupt(ds, level);
                        goto out;
                }
                calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
        }
        if (calc_hash != hash)
                xfs_scrub_da_set_corrupt(ds, level);

out:
        return error;
}

/* Scrub the extended attribute metadata. */
int
xfs_scrub_xattr(
        struct xfs_scrub_context        *sc)
{
        struct xfs_scrub_xattr          sx;
        struct attrlist_cursor_kern     cursor = { 0 };
        xfs_dablk_t                     last_checked = -1U;
        int                             error = 0;

        if (!xfs_inode_hasattr(sc->ip))
                return -ENOENT;

        memset(&sx, 0, sizeof(sx));
        /* Check attribute tree structure */
        error = xfs_scrub_da_btree(sc, XFS_ATTR_FORK, xfs_scrub_xattr_rec,
                        &last_checked);
        if (error)
                goto out;

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        /* Check that every attr key can also be looked up by hash. */
        sx.context.dp = sc->ip;
        sx.context.cursor = &cursor;
        sx.context.resynch = 1;
        sx.context.put_listent = xfs_scrub_xattr_listent;
        sx.context.tp = sc->tp;
        sx.context.flags = ATTR_INCOMPLETE;
        sx.sc = sc;

        /*
         * Look up every xattr in this file by name.
         *
         * Use the backend implementation of xfs_attr_list to call
         * xfs_scrub_xattr_listent on every attribute key in this inode.
         * In other words, we use the same iterator/callback mechanism
         * that listattr uses to scrub extended attributes, though in our
         * _listent function, we check the value of the attribute.
         *
         * The VFS only locks i_rwsem when modifying attrs, so keep all
         * three locks held because that's the only way to ensure we're
         * the only thread poking into the da btree.  We traverse the da
         * btree while holding a leaf buffer locked for the xattr name
         * iteration, which doesn't really follow the usual buffer
         * locking order.
         */
        error = xfs_attr_list_int_ilocked(&sx.context);
        if (!xfs_scrub_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
                goto out;
out:
        return error;
}