Merge tag 'ovl-fixes-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "Fix some bugs and documentation"

* tag 'ovl-fixes-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  docs: filesystems: overlayfs: Fix restview warnings
  docs: filesystems: overlayfs: Rename overlayfs.txt to .rst
  ovl: relax WARN_ON() on rename to self
  ovl: fix corner case of non-unique st_dev;st_ino
  ovl: don't use a temp buf for encoding real fh
  ovl: make sure that real fid is 32bit aligned in memory
  ovl: fix lookup failure on multi lower squashfs

Author: torvalds

Documentation/filesystems/overlayfs.txt renamed to Documentation/filesystems/overlayfs.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
 Written by: Neil Brown
 Please see MAINTAINERS file for where to send questions.
 
@@ -181,7 +183,7 @@ Kernel config options:
     worried about backward compatibility with kernels that have the redirect_dir
     feature and follow redirects even if turned off.
 
-Module options (can also be changed through /sys/module/overlay/parameters/*):
+Module options (can also be changed through /sys/module/overlay/parameters/):
 
 - "redirect_dir=BOOL":
     See OVERLAY_FS_REDIRECT_DIR kernel config option above.
@@ -263,7 +265,7 @@ top, lower2 the middle and lower3 the bottom layer.
 
 
 Metadata only copy up
---------------------
+---------------------
 
 When metadata only copy up feature is enabled, overlayfs will only copy
 up metadata (as opposed to whole file), when a metadata specific operation
@@ -286,10 +288,10 @@ pointed by REDIRECT. This should not be possible on local system as setting
 "trusted." xattrs will require CAP_SYS_ADMIN. But it should be possible
 for untrusted layers like from a pen drive.
 
-Note: redirect_dir={off|nofollow|follow(*)} conflicts with metacopy=on, and
+Note: redirect_dir={off|nofollow|follow[*]} conflicts with metacopy=on, and
 results in an error.
 
-(*) redirect_dir=follow only conflicts with metacopy=on if upperdir=... is
+[*] redirect_dir=follow only conflicts with metacopy=on if upperdir=... is
 given.
 
 Sharing and copying layers

MAINTAINERS

@@ -12394,7 +12394,7 @@ L:	[email protected]
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git
 S:	Supported
 F:	fs/overlayfs/
-F:	Documentation/filesystems/overlayfs.txt
+F:	Documentation/filesystems/overlayfs.rst
 
 P54 WIRELESS DRIVER
 M:	Christian Lamparter <[email protected]>

fs/overlayfs/copy_up.c

@@ -227,13 +227,17 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
 {
 	struct ovl_fh *fh;
-	int fh_type, fh_len, dwords;
-	void *buf;
+	int fh_type, dwords;
 	int buflen = MAX_HANDLE_SZ;
 	uuid_t *uuid = &real->d_sb->s_uuid;
+	int err;
 
-	buf = kmalloc(buflen, GFP_KERNEL);
-	if (!buf)
+	/* Make sure the real fid stays 32bit aligned */
+	BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
+	BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
+
+	fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL);
+	if (!fh)
 		return ERR_PTR(-ENOMEM);
 
 	/*
@@ -242,42 +246,35 @@ struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
 	 * the price or reconnecting the dentry.
 	 */
 	dwords = buflen >> 2;
-	fh_type = exportfs_encode_fh(real, buf, &dwords, 0);
+	fh_type = exportfs_encode_fh(real, (void *)fh->fb.fid, &dwords, 0);
 	buflen = (dwords << 2);
 
-	fh = ERR_PTR(-EIO);
+	err = -EIO;
 	if (WARN_ON(fh_type < 0) ||
 	    WARN_ON(buflen > MAX_HANDLE_SZ) ||
 	    WARN_ON(fh_type == FILEID_INVALID))
-		goto out;
+		goto out_err;
 
-	BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
-	fh_len = offsetof(struct ovl_fh, fid) + buflen;
-	fh = kmalloc(fh_len, GFP_KERNEL);
-	if (!fh) {
-		fh = ERR_PTR(-ENOMEM);
-		goto out;
-	}
-
-	fh->version = OVL_FH_VERSION;
-	fh->magic = OVL_FH_MAGIC;
-	fh->type = fh_type;
-	fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
+	fh->fb.version = OVL_FH_VERSION;
+	fh->fb.magic = OVL_FH_MAGIC;
+	fh->fb.type = fh_type;
+	fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN;
 	/*
 	 * When we will want to decode an overlay dentry from this handle
 	 * and all layers are on the same fs, if we get a disconncted real
 	 * dentry when we decode fid, the only way to tell if we should assign
 	 * it to upperdentry or to lowerstack is by checking this flag.
 	 */
 	if (is_upper)
-		fh->flags |= OVL_FH_FLAG_PATH_UPPER;
-	fh->len = fh_len;
-	fh->uuid = *uuid;
-	memcpy(fh->fid, buf, buflen);
+		fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
+	fh->fb.len = sizeof(fh->fb) + buflen;
+	fh->fb.uuid = *uuid;
 
-out:
-	kfree(buf);
 	return fh;
+
+out_err:
+	kfree(fh);
+	return ERR_PTR(err);
 }
 
 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
@@ -300,8 +297,8 @@ int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 	/*
 	 * Do not fail when upper doesn't support xattrs.
 	 */
-	err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
-				 fh ? fh->len : 0, 0);
+	err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh->buf,
+				 fh ? fh->fb.len : 0, 0);
 	kfree(fh);
 
 	return err;
@@ -317,7 +314,7 @@ static int ovl_set_upper_fh(struct dentry *upper, struct dentry *index)
 	if (IS_ERR(fh))
 		return PTR_ERR(fh);
 
-	err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh, fh->len, 0);
+	err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh->buf, fh->fb.len, 0);
 
 	kfree(fh);
 	return err;

fs/overlayfs/dir.c

@@ -1170,7 +1170,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 	if (newdentry == trap)
 		goto out_dput;
 
-	if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
+	if (olddentry->d_inode == newdentry->d_inode)
 		goto out_dput;
 
 	err = 0;

fs/overlayfs/export.c

@@ -211,10 +211,11 @@ static int ovl_check_encode_origin(struct dentry *dentry)
 	return 1;
 }
 
-static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
+static int ovl_dentry_to_fid(struct dentry *dentry, u32 *fid, int buflen)
 {
 	struct ovl_fh *fh = NULL;
 	int err, enc_lower;
+	int len;
 
 	/*
 	 * Check if we should encode a lower or upper file handle and maybe
@@ -231,43 +232,29 @@ static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
 		return PTR_ERR(fh);
 
 	err = -EOVERFLOW;
-	if (fh->len > buflen)
+	len = OVL_FH_LEN(fh);
+	if (len > buflen)
 		goto fail;
 
-	memcpy(buf, (char *)fh, fh->len);
-	err = fh->len;
+	memcpy(fid, fh, len);
+	err = len;
 
 out:
 	kfree(fh);
 	return err;
 
 fail:
 	pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
-			    dentry, err, buflen, fh ? (int)fh->len : 0,
-			    fh ? fh->type : 0);
+			    dentry, err, buflen, fh ? (int)fh->fb.len : 0,
+			    fh ? fh->fb.type : 0);
 	goto out;
 }
 
-static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
-{
-	int res, len = *max_len << 2;
-
-	res = ovl_d_to_fh(dentry, (char *)fid, len);
-	if (res <= 0)
-		return FILEID_INVALID;
-
-	len = res;
-
-	/* Round up to dwords */
-	*max_len = (len + 3) >> 2;
-	return OVL_FILEID;
-}
-
 static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
 			 struct inode *parent)
 {
 	struct dentry *dentry;
-	int type;
+	int bytes = *max_len << 2;
 
 	/* TODO: encode connectable file handles */
 	if (parent)
@@ -277,10 +264,14 @@ static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
 	if (WARN_ON(!dentry))
 		return FILEID_INVALID;
 
-	type = ovl_dentry_to_fh(dentry, fid, max_len);
-
+	bytes = ovl_dentry_to_fid(dentry, fid, bytes);
 	dput(dentry);
-	return type;
+	if (bytes <= 0)
+		return FILEID_INVALID;
+
+	*max_len = bytes >> 2;
+
+	return OVL_FILEID_V1;
 }
 
 /*
@@ -777,37 +768,64 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
 	goto out;
 }
 
+static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
+{
+	struct ovl_fh *fh;
+
+	/* If on-wire inner fid is aligned - nothing to do */
+	if (fh_type == OVL_FILEID_V1)
+		return (struct ovl_fh *)fid;
+
+	if (fh_type != OVL_FILEID_V0)
+		return ERR_PTR(-EINVAL);
+
+	fh = kzalloc(buflen, GFP_KERNEL);
+	if (!fh)
+		return ERR_PTR(-ENOMEM);
+
+	/* Copy unaligned inner fh into aligned buffer */
+	memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);
+	return fh;
+}
+
 static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
 				       int fh_len, int fh_type)
 {
 	struct dentry *dentry = NULL;
-	struct ovl_fh *fh = (struct ovl_fh *) fid;
+	struct ovl_fh *fh = NULL;
 	int len = fh_len << 2;
 	unsigned int flags = 0;
 	int err;
 
-	err = -EINVAL;
-	if (fh_type != OVL_FILEID)
+	fh = ovl_fid_to_fh(fid, len, fh_type);
+	err = PTR_ERR(fh);
+	if (IS_ERR(fh))
 		goto out_err;
 
 	err = ovl_check_fh_len(fh, len);
 	if (err)
 		goto out_err;
 
-	flags = fh->flags;
+	flags = fh->fb.flags;
 	dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
 		 ovl_upper_fh_to_d(sb, fh) :
 		 ovl_lower_fh_to_d(sb, fh);
 	err = PTR_ERR(dentry);
 	if (IS_ERR(dentry) && err != -ESTALE)
 		goto out_err;
 
+out:
+	/* We may have needed to re-align OVL_FILEID_V0 */
+	if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid)
+		kfree(fh);
+
 	return dentry;
 
 out_err:
 	pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
-			    len, fh_type, flags, err);
-	return ERR_PTR(err);
+			    fh_len, fh_type, flags, err);
+	dentry = ERR_PTR(err);
+	goto out;
 }
 
 static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,

fs/overlayfs/inode.c

@@ -200,8 +200,14 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
 			if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
 			    (!ovl_verify_lower(dentry->d_sb) &&
 			     (is_dir || lowerstat.nlink == 1))) {
-				stat->ino = lowerstat.ino;
 				lower_layer = ovl_layer_lower(dentry);
+				/*
+				 * Cannot use origin st_dev;st_ino because
+				 * origin inode content may differ from overlay
+				 * inode content.
+				 */
+				if (samefs || lower_layer->fsid)
+					stat->ino = lowerstat.ino;
 			}
 
 			/*