diff mbox

[21/25] xfs: scrub extended attributes

Message ID 150706338252.19351.5670406854902904109.stgit@magnolia (mailing list archive)
State Superseded
Headers show

Commit Message

Darrick J. Wong Oct. 3, 2017, 8:43 p.m. UTC
From: Darrick J. Wong <darrick.wong@oracle.com>

Scrub the hash tree, keys, and values in an extended attribute structure.
Refactor the attribute code to use the transaction if the caller supplied
one to avoid buffer deadocks.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/Makefile        |    1 
 fs/xfs/libxfs/xfs_fs.h |    3 -
 fs/xfs/scrub/attr.c    |  218 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/common.h  |    2 
 fs/xfs/scrub/scrub.c   |    8 ++
 fs/xfs/scrub/scrub.h   |    2 
 6 files changed, 233 insertions(+), 1 deletion(-)
 create mode 100644 fs/xfs/scrub/attr.c



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Comments

Dave Chinner Oct. 9, 2017, 2:13 a.m. UTC | #1
On Tue, Oct 03, 2017 at 01:43:02PM -0700, Darrick J. Wong wrote:
> +/* Extended Attributes */
> +
> +struct xfs_scrub_xattr {
> +	struct xfs_attr_list_context	context;
> +	struct xfs_scrub_context	*sc;
> +};

A comment here explaining that we are using the listattr callback
infrastructure to scrub the xattr?  And, now that I've got to the
rest of the code, that we don't validate the pointers/values in the
attribute records when doing dabtree record check because we are
doing that indirectly afterwards by reading every attribute value.
And that this follows the pointers for remote attr blocks and reads
them, hence checking the remote attr is valid via verifiers?

And, with that out of the way, what about attributes that listent
skips? i.e. those with the flag that says they are not valid? We
don't check they exist or are valid, and their existence would be
a case for preening the xattr tree...

Otherwise this seems pretty straight forward...

Cheers,

Dave.
Darrick J. Wong Oct. 9, 2017, 9:14 p.m. UTC | #2
On Mon, Oct 09, 2017 at 01:13:12PM +1100, Dave Chinner wrote:
> On Tue, Oct 03, 2017 at 01:43:02PM -0700, Darrick J. Wong wrote:
> > +/* Extended Attributes */
> > +
> > +struct xfs_scrub_xattr {
> > +	struct xfs_attr_list_context	context;
> > +	struct xfs_scrub_context	*sc;
> > +};
> 
> A comment here explaining that we are using the listattr callback
> infrastructure to scrub the xattr?

New comments:

/*
 * 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.
 */

...comes before the definition of xfs_scrub_xattr_listent, and...

/*
 * 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.
 */

...comes right before the call to xfs_attr_list_int_ilocked.

> And, now that I've got to the rest of the code, that we don't validate
> the pointers/values in the attribute records when doing dabtree record
> check because we are doing that indirectly afterwards by reading every
> attribute value.

Correct.

> And that this follows the pointers for remote attr blocks and reads
> them, hence checking the remote attr is valid via verifiers?

Correct.

> And, with that out of the way, what about attributes that listent
> skips?

Oops, I forgot those.

> i.e. those with the flag that says they are not valid?  We don't check
> they exist or are valid, and their existence would be a case for
> preening the xattr tree...

Good point, I'll add those.

> Otherwise this seems pretty straight forward...

Woot.

--D

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
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diff mbox

Patch

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 69aa88e..4d46399 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -148,6 +148,7 @@  xfs-y				+= $(addprefix scrub/, \
 				   trace.o \
 				   agheader.o \
 				   alloc.o \
+				   attr.o \
 				   bmap.o \
 				   btree.o \
 				   common.o \
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index b16d004..0834ce6 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -499,9 +499,10 @@  struct xfs_scrub_metadata {
 #define XFS_SCRUB_TYPE_BMBTA	13	/* attr fork block mapping */
 #define XFS_SCRUB_TYPE_BMBTC	14	/* CoW fork block mapping */
 #define XFS_SCRUB_TYPE_DIR	15	/* directory */
+#define XFS_SCRUB_TYPE_XATTR	16	/* extended attribute */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	16
+#define XFS_SCRUB_TYPE_NR	17
 
 /* i: Repair this metadata. */
 #define XFS_SCRUB_IFLAG_REPAIR		(1 << 0)
diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
new file mode 100644
index 0000000..319c42b
--- /dev/null
+++ b/fs/xfs/scrub/attr.c
@@ -0,0 +1,218 @@ 
+/*
+ * 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)
+{
+	/* Allocate the buffer without the inode lock held. */
+	sc->buf = kmem_zalloc_large(XATTR_SIZE_MAX, 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. */
+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 = {0};
+	int				error = 0;
+
+	sx = container_of(context, struct xfs_scrub_xattr, context);
+
+	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_op_ok(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;
+}
+
+/* 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 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 = { 0 };
+	struct attrlist_cursor_kern	cursor = { 0 };
+	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);
+	if (error)
+		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.sc = sc;
+
+	/*
+	 * Look up every xattr in this file by name.
+	 *
+	 * 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_op_ok(sc, XFS_ATTR_FORK, 0, &error))
+		goto out;
+out:
+	return error;
+}
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index f530301..b2d3bc7 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -96,6 +96,8 @@  int xfs_scrub_setup_inode_bmap_data(struct xfs_scrub_context *sc,
 				    struct xfs_inode *ip);
 int xfs_scrub_setup_directory(struct xfs_scrub_context *sc,
 			      struct xfs_inode *ip);
+int xfs_scrub_setup_xattr(struct xfs_scrub_context *sc,
+			  struct xfs_inode *ip);
 
 void xfs_scrub_ag_free(struct xfs_scrub_context *sc, struct xfs_scrub_ag *sa);
 int xfs_scrub_ag_init(struct xfs_scrub_context *sc, xfs_agnumber_t agno,
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index f3a84d9..d1b80dc 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -152,6 +152,10 @@  xfs_scrub_teardown(
 			iput(VFS_I(sc->ip));
 		sc->ip = NULL;
 	}
+	if (sc->buf) {
+		kmem_free(sc->buf);
+		sc->buf = NULL;
+	}
 	return error;
 }
 
@@ -225,6 +229,10 @@  static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
 		.setup	= xfs_scrub_setup_directory,
 		.scrub	= xfs_scrub_directory,
 	},
+	{ /* extended attributes */
+		.setup	= xfs_scrub_setup_xattr,
+		.scrub	= xfs_scrub_xattr,
+	},
 };
 
 /* This isn't a stable feature, warn once per day. */
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 844506e..d31ff58 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -59,6 +59,7 @@  struct xfs_scrub_context {
 	const struct xfs_scrub_meta_ops	*ops;
 	struct xfs_trans		*tp;
 	struct xfs_inode		*ip;
+	void				*buf;
 	uint				ilock_flags;
 	bool				try_harder;
 
@@ -83,5 +84,6 @@  int xfs_scrub_bmap_data(struct xfs_scrub_context *sc);
 int xfs_scrub_bmap_attr(struct xfs_scrub_context *sc);
 int xfs_scrub_bmap_cow(struct xfs_scrub_context *sc);
 int xfs_scrub_directory(struct xfs_scrub_context *sc);
+int xfs_scrub_xattr(struct xfs_scrub_context *sc);
 
 #endif	/* __XFS_SCRUB_SCRUB_H__ */