ovl: decode pure upper file handles (8556a420) · Commits · 戴 / test

fs/overlayfs/export.c

+97 −0

Original line number	Diff line number	Diff line
		@@ -93,6 +93,103 @@ static int ovl_encode_inode_fh(struct inode inode, u32 fid, int *max_len,
		return type;
		}

		/*
		* Find or instantiate an overlay dentry from real dentries.
		*/
		static struct dentry ovl_obtain_alias(struct super_block sb,
		struct dentry *upper,
		struct ovl_path *lowerpath)
		{
		struct inode *inode;
		struct dentry *dentry;
		struct ovl_entry *oe;
		void *fsdata = &oe;

		/* TODO: obtain non pure-upper */
		if (lowerpath)
		return ERR_PTR(-EIO);

		inode = ovl_get_inode(sb, dget(upper), NULL, NULL, 0);
		if (IS_ERR(inode)) {
		dput(upper);
		return ERR_CAST(inode);
		}

		dentry = d_find_any_alias(inode);
		if (!dentry) {
		dentry = d_alloc_anon(inode->i_sb);
		if (!dentry)
		goto nomem;
		oe = ovl_alloc_entry(0);
		if (!oe)
		goto nomem;

		dentry->d_fsdata = oe;
		ovl_dentry_set_upper_alias(dentry);
		}

		return d_instantiate_anon(dentry, inode);

		nomem:
		iput(inode);
		dput(dentry);
		return ERR_PTR(-ENOMEM);
		}

		static struct dentry ovl_upper_fh_to_d(struct super_block sb,
		struct ovl_fh *fh)
		{
		struct ovl_fs *ofs = sb->s_fs_info;
		struct dentry *dentry;
		struct dentry *upper;

		if (!ofs->upper_mnt)
		return ERR_PTR(-EACCES);

		upper = ovl_decode_fh(fh, ofs->upper_mnt);
		if (IS_ERR_OR_NULL(upper))
		return upper;

		dentry = ovl_obtain_alias(sb, upper, NULL);
		dput(upper);

		return dentry;
		}

		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;
		int len = fh_len << 2;
		unsigned int flags = 0;
		int err;

		err = -EINVAL;
		if (fh_type != OVL_FILEID)
		goto out_err;

		err = ovl_check_fh_len(fh, len);
		if (err)
		goto out_err;

		/* TODO: decode non-upper */
		flags = fh->flags;
		if (flags & OVL_FH_FLAG_PATH_UPPER)
		dentry = ovl_upper_fh_to_d(sb, fh);
		err = PTR_ERR(dentry);
		if (IS_ERR(dentry) && err != -ESTALE)
		goto out_err;

		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);
		}

		const struct export_operations ovl_export_operations = {
		.encode_fh = ovl_encode_inode_fh,
		.fh_to_dentry = ovl_fh_to_dentry,
		};

fs/overlayfs/namei.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -107,7 +107,7 @@ static int ovl_acceptable(void ctx, struct dentry dentry)
		* Return -ENODATA for "origin unknown".
		* Return <0 for an invalid file handle.
		*/
		static int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
		int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
		{
		if (fh_len < sizeof(struct ovl_fh) \|\| fh_len < fh->len)
		return -EINVAL;
		@@ -171,7 +171,7 @@ invalid:
		goto out;
		}

		static struct dentry ovl_decode_fh(struct ovl_fh fh, struct vfsmount *mnt)
		struct dentry ovl_decode_fh(struct ovl_fh fh, struct vfsmount *mnt)
		{
		struct dentry *real;
		int bytes;

fs/overlayfs/overlayfs.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -264,6 +264,8 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)


		/* namei.c */
		int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
		struct dentry ovl_decode_fh(struct ovl_fh fh, struct vfsmount *mnt);
		int ovl_verify_set_fh(struct dentry dentry, const char name,
		struct dentry *real, bool is_upper, bool set);
		int ovl_verify_index(struct ovl_fs ofs, struct dentry index);

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