// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_attr_sf.h"
#include "xfs_parent.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/dabtree.h"
#include "scrub/attr.h"
#include "scrub/listxattr.h"
#include "scrub/repair.h"

/* Free the buffers linked from the xattr buffer. */
static void
xchk_xattr_buf_cleanup(
        void                    *priv)
{
        struct xchk_xattr_buf   *ab = priv;

        kvfree(ab->freemap);
        ab->freemap = NULL;
        kvfree(ab->usedmap);
        ab->usedmap = NULL;
        kvfree(ab->value);
        ab->value = NULL;
        ab->value_sz = 0;
        kvfree(ab->name);
        ab->name = NULL;
}

/*
 * Allocate the free space bitmap if we're trying harder; there are leaf blocks
 * in the attr fork; or we can't tell if there are leaf blocks.
 */
static inline bool
xchk_xattr_want_freemap(
        struct xfs_scrub        *sc)
{
        struct xfs_ifork        *ifp;

        if (sc->flags & XCHK_TRY_HARDER)
                return true;

        if (!sc->ip)
                return true;

        ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);
        if (!ifp)
                return false;

        return xfs_ifork_has_extents(ifp);
}

/*
 * Allocate enough memory to hold an attr value and attr block bitmaps,
 * reallocating the buffer if necessary.  Buffer contents are not preserved
 * across a reallocation.
 */
int
xchk_setup_xattr_buf(
        struct xfs_scrub        *sc,
        size_t                  value_size)
{
        size_t                  bmp_sz;
        struct xchk_xattr_buf   *ab = sc->buf;
        void                    *new_val;

        bmp_sz = sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);

        if (ab)
                goto resize_value;

        ab = kvzalloc_obj(struct xchk_xattr_buf, XCHK_GFP_FLAGS);
        if (!ab)
                return -ENOMEM;
        sc->buf = ab;
        sc->buf_cleanup = xchk_xattr_buf_cleanup;

        ab->usedmap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
        if (!ab->usedmap)
                return -ENOMEM;

        if (xchk_xattr_want_freemap(sc)) {
                ab->freemap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
                if (!ab->freemap)
                        return -ENOMEM;
        }

        if (xchk_could_repair(sc)) {
                ab->name = kvmalloc(XATTR_NAME_MAX + 1, XCHK_GFP_FLAGS);
                if (!ab->name)
                        return -ENOMEM;
        }

resize_value:
        if (ab->value_sz >= value_size)
                return 0;

        if (ab->value) {
                kvfree(ab->value);
                ab->value = NULL;
                ab->value_sz = 0;
        }

        new_val = kvmalloc(value_size, XCHK_GFP_FLAGS);
        if (!new_val)
                return -ENOMEM;

        ab->value = new_val;
        ab->value_sz = value_size;
        return 0;
}

/* Set us up to scrub an inode's extended attributes. */
int
xchk_setup_xattr(
        struct xfs_scrub        *sc)
{
        int                     error;

        if (xchk_could_repair(sc)) {
                error = xrep_setup_xattr(sc);
                if (error)
                        return error;
        }

        /*
         * We failed to get memory while checking attrs, so this time try to
         * get all the memory we're ever going to need.  Allocate the buffer
         * without the inode lock held, which means we can sleep.
         */
        if (sc->flags & XCHK_TRY_HARDER) {
                error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX);
                if (error)
                        return error;
        }

        return xchk_setup_inode_contents(sc, 0);
}

/* Extended Attributes */

/*
 * Check that an extended attribute key can be looked up by hash.
 *
 * We use the extended attribute walk helper 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 int
xchk_xattr_actor(
        struct xfs_scrub        *sc,
        struct xfs_inode        *ip,
        unsigned int            attr_flags,
        const unsigned char     *name,
        unsigned int            namelen,
        const void              *value,
        unsigned int            valuelen,
        void                    *priv)
{
        struct xfs_da_args              args = {
                .attr_filter            = attr_flags & XFS_ATTR_NSP_ONDISK_MASK,
                .geo                    = sc->mp->m_attr_geo,
                .whichfork              = XFS_ATTR_FORK,
                .dp                     = ip,
                .name                   = name,
                .namelen                = namelen,
                .trans                  = sc->tp,
                .valuelen               = valuelen,
                .owner                  = ip->i_ino,
        };
        struct xchk_xattr_buf           *ab;
        int                             error = 0;

        ab = sc->buf;

        if (xchk_should_terminate(sc, &error))
                return error;

        if (attr_flags & ~XFS_ATTR_ONDISK_MASK) {
                xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
                return -ECANCELED;
        }

        if (attr_flags & XFS_ATTR_INCOMPLETE) {
                /* Incomplete attr key, just mark the inode for preening. */
                xchk_ino_set_preen(sc, ip->i_ino);
                return 0;
        }

        /* Does this name make sense? */
        if (!xfs_attr_namecheck(attr_flags, name, namelen)) {
                xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
                return -ECANCELED;
        }

        /* Check parent pointer record. */
        if ((attr_flags & XFS_ATTR_PARENT) &&
            !xfs_parent_valuecheck(sc->mp, value, valuelen)) {
                xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
                return -ECANCELED;
        }

        /*
         * Try to allocate enough memory to extract the attr value.  If that
         * doesn't work, return -EDEADLOCK as a signal to try again with a
         * maximally sized buffer.
         */
        error = xchk_setup_xattr_buf(sc, valuelen);
        if (error == -ENOMEM)
                error = -EDEADLOCK;
        if (error)
                return error;

        /*
         * Parent pointers are matched on attr name and value, so we must
         * supply the xfs_parent_rec here when confirming that the dabtree
         * indexing works correctly.
         */
        if (attr_flags & XFS_ATTR_PARENT)
                memcpy(ab->value, value, valuelen);

        args.value = ab->value;

        /*
         * Get the attr value to ensure that lookup can find this attribute
         * through the dabtree indexing and that remote value retrieval also
         * works correctly.
         */
        xfs_attr_sethash(&args);
        error = xfs_attr_get_ilocked(&args);
        /* ENODATA means the hash lookup failed and the attr is bad */
        if (error == -ENODATA)
                error = -EFSCORRUPTED;
        if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, args.blkno,
                        &error))
                return error;
        if (args.valuelen != valuelen)
                xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);

        return 0;
}

/*
 * 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
 */
bool
xchk_xattr_set_map(
        struct xfs_scrub        *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 this leaf entry's relations to everything else.
 * Returns the number of bytes used for the name/value data.
 */
STATIC void
xchk_xattr_entry(
        struct xchk_da_btree            *ds,
        int                             level,
        char                            *buf_end,
        struct xfs_attr_leafblock       *leaf,
        struct xfs_attr3_icleaf_hdr     *leafhdr,
        struct xfs_attr_leaf_entry      *ent,
        int                             idx,
        unsigned int                    *usedbytes,
        __u32                           *last_hashval)
{
        struct xfs_mount                *mp = ds->state->mp;
        struct xchk_xattr_buf           *ab = ds->sc->buf;
        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)
                xchk_da_set_corrupt(ds, level);

        /* Hash values in order? */
        if (be32_to_cpu(ent->hashval) < *last_hashval)
                xchk_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) {
                xchk_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)
                        xchk_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)
                        xchk_da_set_corrupt(ds, level);
                if (rentry->valueblk == 0 &&
                    !(ent->flags & XFS_ATTR_INCOMPLETE))
                        xchk_da_set_corrupt(ds, level);
        }
        if (name_end > buf_end)
                xchk_da_set_corrupt(ds, level);

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

/* Scrub an attribute leaf. */
STATIC int
xchk_xattr_block(
        struct xchk_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;
        struct xchk_xattr_buf           *ab = 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(ab->usedmap, mp->m_attr_geo->blksize);
        bitmap_zero(ab->freemap, mp->m_attr_geo->blksize);

        /* Check all the padding. */
        if (xfs_has_crc(ds->sc->mp)) {
                struct xfs_attr3_leafblock      *leaf3 = bp->b_addr;

                if (leaf3->hdr.pad1 != 0 || leaf3->hdr.pad2 != 0 ||
                    leaf3->hdr.info.hdr.pad != 0)
                        xchk_da_set_corrupt(ds, level);
        } else {
                if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
                        xchk_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);

        /*
         * Empty xattr leaf blocks mapped at block 0 are probably a byproduct
         * of a race between setxattr and a log shutdown.  Anywhere else in the
         * attr fork is a corruption.
         */
        if (leafhdr.count == 0) {
                if (blk->blkno == 0)
                        xchk_da_set_preen(ds, level);
                else
                        xchk_da_set_corrupt(ds, level);
        }
        if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
                xchk_da_set_corrupt(ds, level);
        if (leafhdr.firstused > mp->m_attr_geo->blksize)
                xchk_da_set_corrupt(ds, level);
        if (leafhdr.firstused < hdrsize)
                xchk_da_set_corrupt(ds, level);
        if (!xchk_xattr_set_map(ds->sc, ab->usedmap, 0, hdrsize))
                xchk_da_set_corrupt(ds, level);
        if (leafhdr.holes)
                xchk_da_set_preen(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)
                xchk_da_set_corrupt(ds, level);

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

        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 (!xchk_xattr_set_map(ds->sc, ab->usedmap, off,
                                sizeof(xfs_attr_leaf_entry_t))) {
                        xchk_da_set_corrupt(ds, level);
                        goto out;
                }

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

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

        /* Construct bitmap of freemap contents. */
        for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
                if (!xchk_xattr_set_map(ds->sc, ab->freemap,
                                leafhdr.freemap[i].base,
                                leafhdr.freemap[i].size))
                        xchk_da_set_corrupt(ds, level);

                /*
                 * freemap entries with zero length and nonzero base can cause
                 * problems with older kernels, so we mark these for preening
                 * even though there's no inconsistency.
                 */
                if (leafhdr.freemap[i].size == 0 &&
                    leafhdr.freemap[i].base > 0)
                        xchk_da_set_preen(ds, level);

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

        /* Look for bits that are set in freemap and are marked in use. */
        if (bitmap_intersects(ab->freemap, ab->usedmap,
                        mp->m_attr_geo->blksize))
                xchk_da_set_corrupt(ds, level);

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

out:
        return 0;
}

/* Scrub a attribute btree record. */
STATIC int
xchk_xattr_rec(
        struct xchk_da_btree            *ds,
        int                             level)
{
        struct xfs_mount                *mp = ds->state->mp;
        struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
        struct xfs_attr_leaf_name_local *lentry;
        struct xfs_attr_leaf_name_remote        *rentry;
        struct xfs_buf                  *bp;
        struct xfs_attr_leaf_entry      *ent;
        xfs_dahash_t                    calc_hash;
        xfs_dahash_t                    hash;
        int                             nameidx;
        int                             hdrsize;
        int                             error;

        ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);

        ent = xfs_attr3_leaf_entryp(blk->bp->b_addr) + blk->index;

        /* Check the whole block, if necessary. */
        error = xchk_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 = xchk_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) {
                xchk_da_set_corrupt(ds, level);
                goto out;
        }

        /* Retrieve the entry and check it. */
        hash = be32_to_cpu(ent->hashval);
        if (ent->flags & ~XFS_ATTR_ONDISK_MASK) {
                xchk_da_set_corrupt(ds, level);
                return 0;
        }
        if (!xfs_attr_check_namespace(ent->flags)) {
                xchk_da_set_corrupt(ds, level);
                return 0;
        }

        if (ent->flags & XFS_ATTR_LOCAL) {
                lentry = (struct xfs_attr_leaf_name_local *)
                                (((char *)bp->b_addr) + nameidx);
                if (lentry->namelen <= 0) {
                        xchk_da_set_corrupt(ds, level);
                        goto out;
                }
                calc_hash = xfs_attr_hashval(mp, ent->flags, lentry->nameval,
                                             lentry->namelen,
                                             lentry->nameval + lentry->namelen,
                                             be16_to_cpu(lentry->valuelen));
        } else {
                rentry = (struct xfs_attr_leaf_name_remote *)
                                (((char *)bp->b_addr) + nameidx);
                if (rentry->namelen <= 0) {
                        xchk_da_set_corrupt(ds, level);
                        goto out;
                }
                if (ent->flags & XFS_ATTR_PARENT) {
                        xchk_da_set_corrupt(ds, level);
                        goto out;
                }
                calc_hash = xfs_attr_hashval(mp, ent->flags, rentry->name,
                                             rentry->namelen, NULL,
                                             be32_to_cpu(rentry->valuelen));
        }
        if (calc_hash != hash)
                xchk_da_set_corrupt(ds, level);

out:
        return error;
}

/* Check space usage of shortform attrs. */
STATIC int
xchk_xattr_check_sf(
        struct xfs_scrub                *sc)
{
        struct xchk_xattr_buf           *ab = sc->buf;
        struct xfs_ifork                *ifp = &sc->ip->i_af;
        struct xfs_attr_sf_hdr          *sf = ifp->if_data;
        struct xfs_attr_sf_entry        *sfe = xfs_attr_sf_firstentry(sf);
        struct xfs_attr_sf_entry        *next;
        unsigned char                   *end = ifp->if_data + ifp->if_bytes;
        int                             i;
        int                             error = 0;

        bitmap_zero(ab->usedmap, ifp->if_bytes);
        xchk_xattr_set_map(sc, ab->usedmap, 0, sizeof(*sf));

        if ((unsigned char *)sfe > end) {
                xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                return 0;
        }

        for (i = 0; i < sf->count; i++) {
                unsigned char           *name = sfe->nameval;
                unsigned char           *value = &sfe->nameval[sfe->namelen];

                if (xchk_should_terminate(sc, &error))
                        return error;

                next = xfs_attr_sf_nextentry(sfe);
                if ((unsigned char *)next > end) {
                        xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                        break;
                }

                /*
                 * Shortform entries do not set LOCAL or INCOMPLETE, so the
                 * only valid flag bits here are for namespaces.
                 */
                if (sfe->flags & ~XFS_ATTR_NSP_ONDISK_MASK) {
                        xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                        break;
                }

                if (!xchk_xattr_set_map(sc, ab->usedmap,
                                (char *)sfe - (char *)sf,
                                sizeof(struct xfs_attr_sf_entry))) {
                        xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                        break;
                }

                if (!xchk_xattr_set_map(sc, ab->usedmap,
                                (char *)name - (char *)sf,
                                sfe->namelen)) {
                        xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                        break;
                }

                if (!xchk_xattr_set_map(sc, ab->usedmap,
                                (char *)value - (char *)sf,
                                sfe->valuelen)) {
                        xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
                        break;
                }

                sfe = next;
        }

        return 0;
}

/* Scrub the extended attribute metadata. */
int
xchk_xattr(
        struct xfs_scrub                *sc)
{
        xfs_dablk_t                     last_checked = -1U;
        int                             error = 0;

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

        /* Allocate memory for xattr checking. */
        error = xchk_setup_xattr_buf(sc, 0);
        if (error == -ENOMEM)
                return -EDEADLOCK;
        if (error)
                return error;

        /* Check the physical structure of the xattr. */
        if (sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL)
                error = xchk_xattr_check_sf(sc);
        else
                error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
                                &last_checked);
        if (error)
                return error;

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return 0;

        /*
         * Look up every xattr in this file by name and hash.
         *
         * 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 = xchk_xattr_walk(sc, sc->ip, xchk_xattr_actor, NULL, NULL);
        if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
                return error;

        return 0;
}