Merge tag 'make-attr-fork-permanent-5.20_2022-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.20-mergeB

xfs: make attr forks permanent

This series fixes a use-after-free bug that syzbot uncovered.  The UAF
itself is a result of a race condition between getxattr and removexattr
because callers to getxattr do not necessarily take any sort of locks
before calling into the filesystem.

Although the race condition itself can be fixed through clever use of a
memory barrier, further consideration of the use cases of extended
attributes shows that most files always have at least one attribute, so
we might as well make them permanent.

v2: Minor tweaks suggested by Dave, and convert some more macros to
helper functions.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

* tag 'make-attr-fork-permanent-5.20_2022-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: replace inode fork size macros with functions
  xfs: replace XFS_IFORK_Q with a proper predicate function
  xfs: use XFS_IFORK_Q to determine the presence of an xattr fork
  xfs: make inode attribute forks a permanent part of struct xfs_inode
  xfs: convert XFS_IFORK_PTR to a static inline helper

1 files changed, 40 insertions, 41 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 88828fcf0453..e56723dc9cd5 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -128,7 +128,7 @@ xfs_bmbt_lookup_first(
  */
 static inline bool xfs_bmap_needs_btree(struct xfs_inode *ip, int whichfork)
 {
-	struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
 
 	return whichfork != XFS_COW_FORK &&
 		ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
@@ -140,7 +140,7 @@ static inline bool xfs_bmap_needs_btree(struct xfs_inode *ip, int whichfork)
  */
 static inline bool xfs_bmap_wants_extents(struct xfs_inode *ip, int whichfork)
 {
-	struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork);
 
 	return whichfork != XFS_COW_FORK &&
 		ifp->if_format == XFS_DINODE_FMT_BTREE &&
@@ -319,7 +319,7 @@ xfs_bmap_check_leaf_extents(
 	int			whichfork)	/* data or attr fork */
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_btree_block	*block;	/* current btree block */
 	xfs_fsblock_t		bno;	/* block # of "block" */
 	struct xfs_buf		*bp;	/* buffer for "block" */
@@ -538,7 +538,7 @@ xfs_bmap_btree_to_extents(
 	int			*logflagsp, /* inode logging flags */
 	int			whichfork)  /* data or attr fork */
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_btree_block	*rblock = ifp->if_broot;
 	struct xfs_btree_block	*cblock;/* child btree block */
@@ -616,7 +616,7 @@ xfs_bmap_extents_to_btree(
 
 	mp = ip->i_mount;
 	ASSERT(whichfork != XFS_COW_FORK);
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(ifp->if_format == XFS_DINODE_FMT_EXTENTS);
 
 	/*
@@ -745,7 +745,7 @@ xfs_bmap_local_to_extents_empty(
 	struct xfs_inode	*ip,
 	int			whichfork)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 
 	ASSERT(whichfork != XFS_COW_FORK);
 	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
@@ -785,7 +785,7 @@ xfs_bmap_local_to_extents(
 	 * So sending the data fork of a regular inode is invalid.
 	 */
 	ASSERT(!(S_ISREG(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK));
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
 
 	if (!ifp->if_bytes) {
@@ -880,7 +880,7 @@ xfs_bmap_add_attrfork_btree(
 
 	mp = ip->i_mount;
 
-	if (XFS_BMAP_BMDR_SPACE(block) <= XFS_IFORK_DSIZE(ip))
+	if (XFS_BMAP_BMDR_SPACE(block) <= xfs_inode_data_fork_size(ip))
 		*flags |= XFS_ILOG_DBROOT;
 	else {
 		cur = xfs_bmbt_init_cursor(mp, tp, ip, XFS_DATA_FORK);
@@ -920,7 +920,7 @@ xfs_bmap_add_attrfork_extents(
 	int			error;		/* error return value */
 
 	if (ip->i_df.if_nextents * sizeof(struct xfs_bmbt_rec) <=
-	    XFS_IFORK_DSIZE(ip))
+	    xfs_inode_data_fork_size(ip))
 		return 0;
 	cur = NULL;
 	error = xfs_bmap_extents_to_btree(tp, ip, &cur, 0, flags,
@@ -951,7 +951,7 @@ xfs_bmap_add_attrfork_local(
 {
 	struct xfs_da_args	dargs;		/* args for dir/attr code */
 
-	if (ip->i_df.if_bytes <= XFS_IFORK_DSIZE(ip))
+	if (ip->i_df.if_bytes <= xfs_inode_data_fork_size(ip))
 		return 0;
 
 	if (S_ISDIR(VFS_I(ip)->i_mode)) {
@@ -1023,7 +1023,7 @@ xfs_bmap_add_attrfork(
 	int			logflags;	/* logging flags */
 	int			error;		/* error return value */
 
-	ASSERT(XFS_IFORK_Q(ip) == 0);
+	ASSERT(xfs_inode_has_attr_fork(ip) == 0);
 
 	mp = ip->i_mount;
 	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
@@ -1034,16 +1034,15 @@ xfs_bmap_add_attrfork(
 			rsvd, &tp);
 	if (error)
 		return error;
-	if (XFS_IFORK_Q(ip))
+	if (xfs_inode_has_attr_fork(ip))
 		goto trans_cancel;
 
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	error = xfs_bmap_set_attrforkoff(ip, size, &version);
 	if (error)
 		goto trans_cancel;
-	ASSERT(ip->i_afp == NULL);
 
-	ip->i_afp = xfs_ifork_alloc(XFS_DINODE_FMT_EXTENTS, 0);
+	xfs_ifork_init_attr(ip, XFS_DINODE_FMT_EXTENTS, 0);
 	logflags = 0;
 	switch (ip->i_df.if_format) {
 	case XFS_DINODE_FMT_LOCAL:
@@ -1116,7 +1115,7 @@ xfs_iread_bmbt_block(
 	xfs_extnum_t		num_recs;
 	xfs_extnum_t		j;
 	int			whichfork = cur->bc_ino.whichfork;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 
 	block = xfs_btree_get_block(cur, level, &bp);
 
@@ -1164,7 +1163,7 @@ xfs_iread_extents(
 	int			whichfork)
 {
 	struct xfs_iread_state	ir;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_btree_cur	*cur;
 	int			error;
@@ -1208,7 +1207,7 @@ xfs_bmap_first_unused(
 	xfs_fileoff_t		*first_unused,	/* unused block */
 	int			whichfork)	/* data or attr fork */
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec	got;
 	struct xfs_iext_cursor	icur;
 	xfs_fileoff_t		lastaddr = 0;
@@ -1255,7 +1254,7 @@ xfs_bmap_last_before(
 	xfs_fileoff_t		*last_block,	/* last block */
 	int			whichfork)	/* data or attr fork */
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec	got;
 	struct xfs_iext_cursor	icur;
 	int			error;
@@ -1289,7 +1288,7 @@ xfs_bmap_last_extent(
 	struct xfs_bmbt_irec	*rec,
 	int			*is_empty)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_iext_cursor	icur;
 	int			error;
 
@@ -1355,7 +1354,7 @@ xfs_bmap_last_offset(
 	xfs_fileoff_t		*last_block,
 	int			whichfork)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec	rec;
 	int			is_empty;
 	int			error;
@@ -1389,7 +1388,7 @@ xfs_bmap_add_extent_delay_real(
 	int			whichfork)
 {
 	struct xfs_mount	*mp = bma->ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
 	struct xfs_bmbt_irec	*new = &bma->got;
 	int			error;	/* error return value */
 	int			i;	/* temp state */
@@ -1955,7 +1954,7 @@ xfs_bmap_add_extent_unwritten_real(
 	*logflagsp = 0;
 
 	cur = *curp;
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 
 	ASSERT(!isnullstartblock(new->br_startblock));
 
@@ -2480,7 +2479,7 @@ xfs_bmap_add_extent_hole_delay(
 	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
 	xfs_filblks_t		temp;	 /* temp for indirect calculations */
 
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(isnullstartblock(new->br_startblock));
 
 	/*
@@ -2616,7 +2615,7 @@ xfs_bmap_add_extent_hole_real(
 	int			*logflagsp,
 	uint32_t		flags)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_btree_cur	*cur = *curp;
 	int			error;	/* error return value */
@@ -3867,7 +3866,7 @@ xfs_bmapi_read(
 {
 	struct xfs_mount	*mp = ip->i_mount;
 	int			whichfork = xfs_bmapi_whichfork(flags);
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec	got;
 	xfs_fileoff_t		obno;
 	xfs_fileoff_t		end;
@@ -3960,7 +3959,7 @@ xfs_bmapi_reserve_delalloc(
 	int			eof)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	xfs_extlen_t		alen;
 	xfs_extlen_t		indlen;
 	int			error;
@@ -4087,7 +4086,7 @@ xfs_bmapi_allocate(
 {
 	struct xfs_mount	*mp = bma->ip->i_mount;
 	int			whichfork = xfs_bmapi_whichfork(bma->flags);
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
 	int			tmp_logflags = 0;
 	int			error;
 
@@ -4186,7 +4185,7 @@ xfs_bmapi_convert_unwritten(
 	uint32_t		flags)
 {
 	int			whichfork = xfs_bmapi_whichfork(flags);
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
 	int			tmp_logflags = 0;
 	int			error;
 
@@ -4263,7 +4262,7 @@ xfs_bmapi_minleft(
 	struct xfs_inode	*ip,
 	int			fork)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, fork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, fork);
 
 	if (tp && tp->t_firstblock != NULLFSBLOCK)
 		return 0;
@@ -4284,7 +4283,7 @@ xfs_bmapi_finish(
 	int			whichfork,
 	int			error)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(bma->ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(bma->ip, whichfork);
 
 	if ((bma->logflags & xfs_ilog_fext(whichfork)) &&
 	    ifp->if_format != XFS_DINODE_FMT_EXTENTS)
@@ -4323,7 +4322,7 @@ xfs_bmapi_write(
 	};
 	struct xfs_mount	*mp = ip->i_mount;
 	int			whichfork = xfs_bmapi_whichfork(flags);
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	xfs_fileoff_t		end;		/* end of mapped file region */
 	bool			eof = false;	/* after the end of extents */
 	int			error;		/* error return */
@@ -4504,7 +4503,7 @@ xfs_bmapi_convert_delalloc(
 	struct iomap		*iomap,
 	unsigned int		*seq)
 {
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_mount	*mp = ip->i_mount;
 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 	struct xfs_bmalloca	bma = { NULL };
@@ -4641,7 +4640,7 @@ xfs_bmapi_remap(
 	int			whichfork = xfs_bmapi_whichfork(flags);
 	int			logflags = 0, error;
 
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(len > 0);
 	ASSERT(len <= (xfs_filblks_t)XFS_MAX_BMBT_EXTLEN);
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
@@ -4798,7 +4797,7 @@ xfs_bmap_del_extent_delay(
 	struct xfs_bmbt_irec	*del)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec	new;
 	int64_t			da_old, da_new, da_diff = 0;
 	xfs_fileoff_t		del_endoff, got_endoff;
@@ -4925,7 +4924,7 @@ xfs_bmap_del_extent_cow(
 	struct xfs_bmbt_irec	*del)
 {
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 	struct xfs_bmbt_irec	new;
 	xfs_fileoff_t		del_endoff, got_endoff;
 	uint32_t		state = BMAP_COWFORK;
@@ -5023,7 +5022,7 @@ xfs_bmap_del_extent_real(
 	mp = ip->i_mount;
 	XFS_STATS_INC(mp, xs_del_exlist);
 
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	ASSERT(del->br_blockcount > 0);
 	xfs_iext_get_extent(ifp, icur, &got);
 	ASSERT(got.br_startoff <= del->br_startoff);
@@ -5289,7 +5288,7 @@ __xfs_bunmapi(
 
 	whichfork = xfs_bmapi_whichfork(flags);
 	ASSERT(whichfork != XFS_COW_FORK);
-	ifp = XFS_IFORK_PTR(ip, whichfork);
+	ifp = xfs_ifork_ptr(ip, whichfork);
 	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(ifp)))
 		return -EFSCORRUPTED;
 	if (xfs_is_shutdown(mp))
@@ -5630,7 +5629,7 @@ xfs_bmse_merge(
 	struct xfs_btree_cur		*cur,
 	int				*logflags)	/* output */
 {
-	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_bmbt_irec		new;
 	xfs_filblks_t			blockcount;
 	int				error, i;
@@ -5751,7 +5750,7 @@ xfs_bmap_collapse_extents(
 {
 	int			whichfork = XFS_DATA_FORK;
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_btree_cur	*cur = NULL;
 	struct xfs_bmbt_irec	got, prev;
 	struct xfs_iext_cursor	icur;
@@ -5866,7 +5865,7 @@ xfs_bmap_insert_extents(
 {
 	int			whichfork = XFS_DATA_FORK;
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_btree_cur	*cur = NULL;
 	struct xfs_bmbt_irec	got, next;
 	struct xfs_iext_cursor	icur;
@@ -5966,7 +5965,7 @@ xfs_bmap_split_extent(
 	xfs_fileoff_t		split_fsb)
 {
 	int				whichfork = XFS_DATA_FORK;
-	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, whichfork);
 	struct xfs_btree_cur		*cur = NULL;
 	struct xfs_bmbt_irec		got;
 	struct xfs_bmbt_irec		new; /* split extent */