[PATCH] xfs: verify inline directory data forks

["Darrick J. Wong" <darrick.wong@oracle.com>]

When we're reading or writing the data fork of an inline directory,
check the contents to make sure we're not overflowing buffers or eating
garbage data.  xfs/348 corrupts an inline symlink into an inline
directory, triggering a buffer overflow bug.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_dir2_data.c  |   73 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_dir2_priv.h  |    2 +
 fs/xfs/libxfs/xfs_inode_fork.c |   22 ++++++++++--
 fs/xfs/libxfs/xfs_inode_fork.h |    2 +
 fs/xfs/xfs_inode.c             |   12 +++++--
 5 files changed, 104 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index d478065..fb6f32d 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -33,6 +33,79 @@
 #include "xfs_cksum.h"
 #include "xfs_log.h"
 
+/* Check the consistency of an inline directory. */
+int
+xfs_dir3_inline_check(
+	struct xfs_mount		*mp,
+	struct xfs_dinode		*dip,
+	int				size)
+{
+	struct xfs_dir2_sf_entry	*sfep;
+	struct xfs_dir2_sf_entry	*next_sfep;
+	struct xfs_dir2_sf_hdr		*sfp;
+	char				*endp;
+	const struct xfs_dir_ops	*dops;
+	xfs_ino_t			ino;
+	int				i;
+	__uint8_t			filetype;
+
+	dops = xfs_dir_get_ops(mp, NULL);
+
+	/*
+	 * Give up if the directory is way too short.
+	 */
+	XFS_WANT_CORRUPTED_RETURN(mp, size >
+			offsetof(struct xfs_dir2_sf_hdr, parent));
+
+	sfp = (struct xfs_dir2_sf_hdr *)XFS_DFORK_PTR(dip, XFS_DATA_FORK);
+	endp = (char *)sfp + size;
+
+	XFS_WANT_CORRUPTED_RETURN(mp, size >=
+			xfs_dir2_sf_hdr_size(sfp->i8count));
+
+	/* Check .. entry */
+	ino = dops->sf_get_parent_ino(sfp);
+	XFS_WANT_CORRUPTED_RETURN(mp, !xfs_dir_ino_validate(mp, ino));
+
+	/*
+	 * Loop while there are more entries and put'ing works.
+	 */
+	sfep = xfs_dir2_sf_firstentry(sfp);
+	for (i = 0; i < sfp->count; i++) {
+		/*
+		 * struct xfs_dir2_sf_entry has a variable length.
+		 * Check the fixed-offset parts of the structure are
+		 * within the data buffer.
+		 */
+		XFS_WANT_CORRUPTED_RETURN(mp,
+				((char *)sfep + sizeof(*sfep)) < endp);
+
+		/* Don't allow names with known bad length. */
+		XFS_WANT_CORRUPTED_RETURN(mp, sfep->namelen > 0);
+		XFS_WANT_CORRUPTED_RETURN(mp, sfep->namelen < MAXNAMELEN);
+
+		/*
+		 * Check that the variable-length part of the structure is
+		 * within the data buffer.  The next entry starts after the
+		 * name component, so nextentry is an acceptable test.
+		 */
+		next_sfep = dops->sf_nextentry(sfp, sfep);
+		XFS_WANT_CORRUPTED_RETURN(mp, endp >= (char *)next_sfep);
+
+		/* Check the inode number. */
+		ino = dops->sf_get_ino(sfp, sfep);
+		XFS_WANT_CORRUPTED_RETURN(mp, !xfs_dir_ino_validate(mp, ino));
+
+		/* Check the file type. */
+		filetype = dops->sf_get_ftype(sfep);
+		XFS_WANT_CORRUPTED_RETURN(mp, filetype < XFS_DIR3_FT_MAX);
+
+		sfep = next_sfep;
+	}
+
+	return 0;
+}
+
 /*
  * Check the consistency of the data block.
  * The input can also be a block-format directory.
diff --git a/fs/xfs/libxfs/xfs_dir2_priv.h b/fs/xfs/libxfs/xfs_dir2_priv.h
index d04547f..e4f489b 100644
--- a/fs/xfs/libxfs/xfs_dir2_priv.h
+++ b/fs/xfs/libxfs/xfs_dir2_priv.h
@@ -44,6 +44,8 @@ extern int xfs_dir2_leaf_to_block(struct xfs_da_args *args,
 #define	xfs_dir3_data_check(dp,bp)
 #endif
 
+extern int xfs_dir3_inline_check(struct xfs_mount *mp, struct xfs_dinode *dip,
+		int size);
 extern int __xfs_dir3_data_check(struct xfs_inode *dp, struct xfs_buf *bp);
 extern int xfs_dir3_data_read(struct xfs_trans *tp, struct xfs_inode *dp,
 		xfs_dablk_t bno, xfs_daddr_t mapped_bno, struct xfs_buf **bpp);
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 25c1e07..2a454cf 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -33,6 +33,8 @@
 #include "xfs_trace.h"
 #include "xfs_attr_sf.h"
 #include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2_priv.h"
 
 kmem_zone_t *xfs_ifork_zone;
 
@@ -320,6 +322,7 @@ xfs_iformat_local(
 	int		whichfork,
 	int		size)
 {
+	int		error;
 
 	/*
 	 * If the size is unreasonable, then something
@@ -336,6 +339,12 @@ xfs_iformat_local(
 		return -EFSCORRUPTED;
 	}
 
+	if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+		error = xfs_dir3_inline_check(ip->i_mount, dip, size);
+		if (error)
+			return error;
+	}
+
 	xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
 	return 0;
 }
@@ -856,7 +865,7 @@ xfs_iextents_copy(
  * In these cases, the format always takes precedence, because the
  * format indicates the current state of the fork.
  */
-void
+int
 xfs_iflush_fork(
 	xfs_inode_t		*ip,
 	xfs_dinode_t		*dip,
@@ -866,6 +875,7 @@ xfs_iflush_fork(
 	char			*cp;
 	xfs_ifork_t		*ifp;
 	xfs_mount_t		*mp;
+	int			error;
 	static const short	brootflag[2] =
 		{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
 	static const short	dataflag[2] =
@@ -874,7 +884,7 @@ xfs_iflush_fork(
 		{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };
 
 	if (!iip)
-		return;
+		return 0;
 	ifp = XFS_IFORK_PTR(ip, whichfork);
 	/*
 	 * This can happen if we gave up in iformat in an error path,
@@ -882,7 +892,7 @@ xfs_iflush_fork(
 	 */
 	if (!ifp) {
 		ASSERT(whichfork == XFS_ATTR_FORK);
-		return;
+		return 0;
 	}
 	cp = XFS_DFORK_PTR(dip, whichfork);
 	mp = ip->i_mount;
@@ -894,6 +904,11 @@ xfs_iflush_fork(
 			ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
 			memcpy(cp, ifp->if_u1.if_data, ifp->if_bytes);
 		}
+		if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+			error = xfs_dir3_inline_check(mp, dip, ifp->if_bytes);
+			if (error)
+				return error;
+		}
 		break;
 
 	case XFS_DINODE_FMT_EXTENTS:
@@ -940,6 +955,7 @@ xfs_iflush_fork(
 		ASSERT(0);
 		break;
 	}
+	return 0;
 }
 
 /*
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 7fb8365..132dc59 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -140,7 +140,7 @@ typedef struct xfs_ifork {
 struct xfs_ifork *xfs_iext_state_to_fork(struct xfs_inode *ip, int state);
 
 int		xfs_iformat_fork(struct xfs_inode *, struct xfs_dinode *);
-void		xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
+int		xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
 				struct xfs_inode_log_item *, int);
 void		xfs_idestroy_fork(struct xfs_inode *, int);
 void		xfs_idata_realloc(struct xfs_inode *, int, int);
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 7eaf1ef..c7fe2c2 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3475,6 +3475,7 @@ xfs_iflush_int(
 	struct xfs_inode_log_item *iip = ip->i_itemp;
 	struct xfs_dinode	*dip;
 	struct xfs_mount	*mp = ip->i_mount;
+	int			error;
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
 	ASSERT(xfs_isiflocked(ip));
@@ -3557,9 +3558,14 @@ xfs_iflush_int(
 	if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
 		ip->i_d.di_flushiter = 0;
 
-	xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
-	if (XFS_IFORK_Q(ip))
-		xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
+	error = xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
+	if (error)
+		return error;
+	if (XFS_IFORK_Q(ip)) {
+		error = xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
+		if (error)
+			return error;
+	}
 	xfs_inobp_check(mp, bp);
 
 	/*