1 files changed, 527 insertions, 0 deletions

diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
new file mode 100644
index 000000000..b6f0c9f3f
--- /dev/null
+++ b/fs/xfs/scrub/attr.c
@@ -0,0 +1,527 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#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_log_format.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 "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/dabtree.h"
+#include "scrub/attr.h"
+
+/*
+ * 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.
+ */
+static int
+xchk_setup_xattr_buf(
+	struct xfs_scrub	*sc,
+	size_t			value_size,
+	gfp_t			flags)
+{
+	size_t			sz;
+	struct xchk_xattr_buf	*ab = sc->buf;
+
+	/*
+	 * We need enough space to read an xattr value from the file or enough
+	 * space to hold three copies of the xattr free space bitmap.  We don't
+	 * need the buffer space for both purposes at the same time.
+	 */
+	sz = 3 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
+	sz = max_t(size_t, sz, value_size);
+
+	/*
+	 * If there's already a buffer, figure out if we need to reallocate it
+	 * to accommodate a larger size.
+	 */
+	if (ab) {
+		if (sz <= ab->sz)
+			return 0;
+		kmem_free(ab);
+		sc->buf = NULL;
+	}
+
+	/*
+	 * Don't zero the buffer upon allocation to avoid runtime overhead.
+	 * All users must be careful never to read uninitialized contents.
+	 */
+	ab = kvmalloc(sizeof(*ab) + sz, flags);
+	if (!ab)
+		return -ENOMEM;
+
+	ab->sz = sz;
+	sc->buf = ab;
+	return 0;
+}
+
+/* Set us up to scrub an inode's extended attributes. */
+int
+xchk_setup_xattr(
+	struct xfs_scrub	*sc)
+{
+	int			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, GFP_KERNEL);
+		if (error)
+			return error;
+	}
+
+	return xchk_setup_inode_contents(sc, 0);
+}
+
+/* Extended Attributes */
+
+struct xchk_xattr {
+	struct xfs_attr_list_context	context;
+	struct xfs_scrub		*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_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
+xchk_xattr_listent(
+	struct xfs_attr_list_context	*context,
+	int				flags,
+	unsigned char			*name,
+	int				namelen,
+	int				valuelen)
+{
+	struct xchk_xattr		*sx;
+	struct xfs_da_args		args = { NULL };
+	int				error = 0;
+
+	sx = container_of(context, struct xchk_xattr, context);
+
+	if (xchk_should_terminate(sx->sc, &error)) {
+		context->seen_enough = error;
+		return;
+	}
+
+	if (flags & XFS_ATTR_INCOMPLETE) {
+		/* Incomplete attr key, just mark the inode for preening. */
+		xchk_ino_set_preen(sx->sc, context->dp->i_ino);
+		return;
+	}
+
+	/* Does this name make sense? */
+	if (!xfs_attr_namecheck(name, namelen)) {
+		xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
+		return;
+	}
+
+	/*
+	 * Try to allocate enough memory to extrat the attr value.  If that
+	 * doesn't work, we overload the seen_enough variable to convey
+	 * the error message back to the main scrub function.
+	 */
+	error = xchk_setup_xattr_buf(sx->sc, valuelen,
+			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (error == -ENOMEM)
+		error = -EDEADLOCK;
+	if (error) {
+		context->seen_enough = error;
+		return;
+	}
+
+	args.op_flags = XFS_DA_OP_NOTIME;
+	args.attr_filter = flags & XFS_ATTR_NSP_ONDISK_MASK;
+	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 = xchk_xattr_valuebuf(sx->sc);
+	args.valuelen = valuelen;
+
+	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(sx->sc, XFS_ATTR_FORK, args.blkno,
+			&error))
+		goto fail_xref;
+	if (args.valuelen != valuelen)
+		xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
+					     args.blkno);
+fail_xref:
+	if (sx->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
+		context->seen_enough = 1;
+	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
+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 the leaf freemap from the usage bitmap.  Returns false if the
+ * attr freemap has problems or points to used space.
+ */
+STATIC bool
+xchk_xattr_check_freemap(
+	struct xfs_scrub		*sc,
+	unsigned long			*map,
+	struct xfs_attr3_icleaf_hdr	*leafhdr)
+{
+	unsigned long			*freemap = xchk_xattr_freemap(sc);
+	unsigned long			*dstmap = xchk_xattr_dstmap(sc);
+	unsigned int			mapsize = sc->mp->m_attr_geo->blksize;
+	int				i;
+
+	/* Construct bitmap of freemap contents. */
+	bitmap_zero(freemap, mapsize);
+	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
+		if (!xchk_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. */
+	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
+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;
+	unsigned long			*usedmap = xchk_xattr_usedmap(ds->sc);
+	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 || rentry->valueblk == 0)
+			xchk_da_set_corrupt(ds, level);
+	}
+	if (name_end > buf_end)
+		xchk_da_set_corrupt(ds, level);
+
+	if (!xchk_xattr_set_map(ds->sc, 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;
+	unsigned long			*usedmap;
+	char				*buf_end;
+	size_t				off;
+	__u32				last_hashval = 0;
+	unsigned int			usedbytes = 0;
+	unsigned int			hdrsize;
+	int				i;
+	int				error;
+
+	if (*last_checked == blk->blkno)
+		return 0;
+
+	/* Allocate memory for block usage checking. */
+	error = xchk_setup_xattr_buf(ds->sc, 0,
+			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (error == -ENOMEM)
+		return -EDEADLOCK;
+	if (error)
+		return error;
+	usedmap = xchk_xattr_usedmap(ds->sc);
+
+	*last_checked = blk->blkno;
+	bitmap_zero(usedmap, mp->m_attr_geo->blksize);
+
+	/* Check all the padding. */
+	if (xfs_has_crc(ds->sc->mp)) {
+		struct xfs_attr3_leafblock	*leaf = bp->b_addr;
+
+		if (leaf->hdr.pad1 != 0 || leaf->hdr.pad2 != 0 ||
+		    leaf->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);
+
+	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, usedmap, 0, hdrsize))
+		xchk_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)
+		xchk_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 (!xchk_xattr_set_map(ds->sc, 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;
+	}
+
+	if (!xchk_xattr_check_freemap(ds->sc, usedmap, &leafhdr))
+		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;
+	unsigned int			badflags;
+	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);
+	badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
+			XFS_ATTR_INCOMPLETE);
+	if ((ent->flags & badflags) != 0)
+		xchk_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) {
+			xchk_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) {
+			xchk_da_set_corrupt(ds, level);
+			goto out;
+		}
+		calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
+	}
+	if (calc_hash != hash)
+		xchk_da_set_corrupt(ds, level);
+
+out:
+	return error;
+}
+
+/* Scrub the extended attribute metadata. */
+int
+xchk_xattr(
+	struct xfs_scrub		*sc)
+{
+	struct xchk_xattr		sx;
+	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 = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_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.resynch = 1;
+	sx.context.put_listent = xchk_xattr_listent;
+	sx.context.tp = sc->tp;
+	sx.context.allow_incomplete = true;
+	sx.sc = sc;
+
+	/*
+	 * Look up every xattr in this file by name.
+	 *
+	 * Use the backend implementation of xfs_attr_list to call
+	 * xchk_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_ilocked(&sx.context);
+	if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
+		goto out;
+
+	/* Did our listent function try to return any errors? */
+	if (sx.context.seen_enough < 0)
+		error = sx.context.seen_enough;
+out:
+	return error;
+}