1 files changed, 63 insertions, 48 deletions

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index cb8ec1f65c03..6f54d70cef27 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -30,7 +30,7 @@ static int ovl_encode_maybe_copy_up(struct dentry *dentry)
 	}
 
 	if (err) {
-		pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
+		pr_warn_ratelimited("failed to copy up on encode (%pd2, err=%i)\n",
 				    dentry, err);
 	}
 
@@ -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
@@ -227,48 +228,33 @@ static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
 	/* Encode an upper or lower file handle */
 	fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
 				ovl_dentry_upper(dentry), !enc_lower);
-	err = PTR_ERR(fh);
 	if (IS_ERR(fh))
-		goto fail;
+		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);
+	pr_warn_ratelimited("failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
+			    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)
@@ -278,10 +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;
 }
 
 /*
@@ -368,7 +358,7 @@ static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
  */
 static struct dentry *ovl_lookup_real_one(struct dentry *connected,
 					  struct dentry *real,
-					  struct ovl_layer *layer)
+					  const struct ovl_layer *layer)
 {
 	struct inode *dir = d_inode(connected);
 	struct dentry *this, *parent = NULL;
@@ -416,7 +406,7 @@ out:
 	return this;
 
 fail:
-	pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
+	pr_warn_ratelimited("failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
 			    real, layer->idx, connected, err);
 	this = ERR_PTR(err);
 	goto out;
@@ -424,17 +414,16 @@ fail:
 
 static struct dentry *ovl_lookup_real(struct super_block *sb,
 				      struct dentry *real,
-				      struct ovl_layer *layer);
+				      const struct ovl_layer *layer);
 
 /*
  * Lookup an indexed or hashed overlay dentry by real inode.
  */
 static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
 					    struct dentry *real,
-					    struct ovl_layer *layer)
+					    const struct ovl_layer *layer)
 {
 	struct ovl_fs *ofs = sb->s_fs_info;
-	struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
 	struct dentry *index = NULL;
 	struct dentry *this = NULL;
 	struct inode *inode;
@@ -476,7 +465,7 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
 		 * recursive call walks back from indexed upper to the topmost
 		 * connected/hashed upper parent (or up to root).
 		 */
-		this = ovl_lookup_real(sb, upper, &upper_layer);
+		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);
 		dput(upper);
 	}
 
@@ -497,7 +486,7 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
  */
 static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
 					       struct dentry *real,
-					       struct ovl_layer *layer)
+					       const struct ovl_layer *layer)
 {
 	struct dentry *next, *parent = NULL;
 	struct dentry *ancestor = ERR_PTR(-EIO);
@@ -550,7 +539,7 @@ static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
  */
 static struct dentry *ovl_lookup_real(struct super_block *sb,
 				      struct dentry *real,
-				      struct ovl_layer *layer)
+				      const struct ovl_layer *layer)
 {
 	struct dentry *connected;
 	int err = 0;
@@ -641,7 +630,7 @@ static struct dentry *ovl_lookup_real(struct super_block *sb,
 	return connected;
 
 fail:
-	pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
+	pr_warn_ratelimited("failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
 			    real, layer->idx, connected, err);
 	dput(connected);
 	return ERR_PTR(err);
@@ -656,8 +645,7 @@ static struct dentry *ovl_get_dentry(struct super_block *sb,
 				     struct dentry *index)
 {
 	struct ovl_fs *ofs = sb->s_fs_info;
-	struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
-	struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
+	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;
 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);
 
 	/*
@@ -778,24 +766,45 @@ out_err:
 	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);
@@ -803,18 +812,24 @@ static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
 	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);
+	pr_warn_ratelimited("failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
+			    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,
 				       int fh_len, int fh_type)
 {
-	pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
+	pr_warn_ratelimited("connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
 	return ERR_PTR(-EACCES);
 }