From patchwork Thu Sep 19 14:06:10 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 13807784 Received: from mail-ej1-f43.google.com (mail-ej1-f43.google.com [209.85.218.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BD2328EA; Thu, 19 Sep 2024 14:06:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726754782; cv=none; b=fyHxbB/m0tjDEeu21FTWo3RA4pUUuCN3W22OV2/xPUJ6T9THZ5KSCCgBWCj06fuaNH500Uu30eZDxatRusG31JdAdMB4VJqajTuZD/gXvT6oN9/J76dL4pS0CPlRSAeToGToZwgtL0E9GFzf04JZsZkorGTMNI4kIno4V+RsBcE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726754782; c=relaxed/simple; bh=O1jhhcUj3IsFFBDDWs8RNVQYM7nR++KsRPrT3QXUJw0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=OpcjdTB+t3ZJYxE8YDIVA/RzHTzxJCvjNCW6xBGP3YfwjI2PDzqS2b3UYUxWk64PEakSe3ASrELo5BYmLtS3FuKHA8yq8m0Q2kT9shqcEU2KXM+oov3owinENwjoOZXJUwwx5kBxKk549gq6Ykr2++6sUqtrd6DuLFFCCP4Z+rU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OQjJk0Ko; arc=none smtp.client-ip=209.85.218.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OQjJk0Ko" Received: by mail-ej1-f43.google.com with SMTP id a640c23a62f3a-a8d43657255so131945366b.0; Thu, 19 Sep 2024 07:06:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1726754779; x=1727359579; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7zFM/SDc601a7c6eWxDpcFbMja292FpzqrursS83914=; b=OQjJk0Ko0o1uMDttmebiBLDg+eTlDI8YhLQlYuah95DPjsWW0+Ytc9xoezZT6eKtU1 3wp9rdekLBKHCSedLNl4gTKeeSUjfSNEvZqqe7usjowM5CpW/Y99Z8HI1fKPJlTVmt9p bdHNfTweT3FT2OQmFBXtZQF2VGH95lSvJQ2RVGAJQIYOZoxXwdwCLaYObe+7gezURL1p TYUgDkAcH94Nh0n9PNmRuzSOSGE019BHryrigZ9BL+54Js49bJ3qJ0ck77X9cOy+naQF zt9GJXOaEk9OmJ70ZMHN6mxWlbY37U1qdjKZf8Zs+9/rGfMBMj5yIy2DhGV4doiw9S+5 GGZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726754779; x=1727359579; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7zFM/SDc601a7c6eWxDpcFbMja292FpzqrursS83914=; b=aWgyqtJBGb+w2YwF9D+WcHGxfodSAG47ADFbSHcAgmEubQlq9+8Zl5FbEwxdSUgSnU zFqpJylNJCjF7N3vT+hHXdP0vuUMLkHsG245tuD+Xsguo2dZDC9zZgpaVk8sNnd8SP0O PZJRrHLArBudhytzqmd6XwWYMmFZWHkbh/JnuNNQldqXIl7hhdtT3B7MPd+IwGQ6A5BI NKV8hsOPrllbRUy9y99vuND6SrBD1bLcVSzXRCxNPMB0+GuSaMTaXKefod2IEPaVdevS VYlFosobRflkhKy0bJ8B0vgJbgXah5dP+OLYT9QQickHPqi7gJFjvp0YzCJFrrql5pVN 6VEQ== X-Forwarded-Encrypted: i=1; AJvYcCWSPAISv0C4eU+9s9iPiw4+CyWUFb1ZGRR9V8MyKRGK5JziXwA8quMUZgt4gWRMdSGiHXWRGasCpB6MkJ5p@vger.kernel.org, AJvYcCXaxSoFYxlGNEaBb5tdOzyXcXbUkWXQfPAb8VZuhmf84SYsOc424+VXWDURw1m9ppad1zFhONZIxFBa@vger.kernel.org X-Gm-Message-State: AOJu0YwaFaxt0c+pk4Ps2STf0skdwCWSp+FbvgF037528Bri7/YNgigL AjGcnns9wlP9RI7Mn0FvHZCEMGd+reUP6O8TLf4Orfe3FdKngsFo X-Google-Smtp-Source: AGHT+IFVW65/x6M/ish4sB3Dy3c2EojrWo1KSmpOdSGAEDTyvANj7b4B+L5C22FNpF1Cti7jToZ5bQ== X-Received: by 2002:a17:907:7fa3:b0:a87:31c:c6c4 with SMTP id a640c23a62f3a-a9047ca725amr2221913166b.24.1726754778255; Thu, 19 Sep 2024 07:06:18 -0700 (PDT) Received: from amir-ThinkPad-T480.arnhem.chello.nl (92-109-99-123.cable.dynamic.v4.ziggo.nl. [92.109.99.123]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a9061330c1fsm719503266b.206.2024.09.19.07.06.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Sep 2024 07:06:17 -0700 (PDT) From: Amir Goldstein To: Jeff Layton Cc: Christian Brauner , Aleksa Sarai , Chuck Lever , linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Subject: [RFC PATCH 1/2] fs: name_to_handle_at() support for connectable file handles Date: Thu, 19 Sep 2024 16:06:10 +0200 Message-Id: <20240919140611.1771651-2-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240919140611.1771651-1-amir73il@gmail.com> References: <20240919140611.1771651-1-amir73il@gmail.com> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 nfsd encodes "connectable" file handles for the subtree_check feature. So far, userspace nfs server could not make use of this functionality. Introduce a new flag AT_HANDLE_CONNECTABLE to name_to_handle_at(2). When used, the encoded file handle is "connectable". Note that decoding a "connectable" file handle with open_by_handle_at(2) is not guarandteed to return a "connected" fd (i.e. fd with known path). A new opt-in API would be needed to guarantee a "connected" fd. Signed-off-by: Amir Goldstein --- fs/fhandle.c | 24 ++++++++++++++++++++---- include/uapi/linux/fcntl.h | 1 + 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/fs/fhandle.c b/fs/fhandle.c index 8cb665629f4a..956d9b25d4f7 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -31,6 +31,11 @@ static long do_sys_name_to_handle(const struct path *path, if (!exportfs_can_encode_fh(path->dentry->d_sb->s_export_op, fh_flags)) return -EOPNOTSUPP; + /* Do not encode a connectable handle for a disconnected dentry */ + if (fh_flags & EXPORT_FH_CONNECTABLE && + path->dentry->d_flags & DCACHE_DISCONNECTED) + return -EACCES; + if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) return -EFAULT; @@ -45,7 +50,7 @@ static long do_sys_name_to_handle(const struct path *path, /* convert handle size to multiple of sizeof(u32) */ handle_dwords = f_handle.handle_bytes >> 2; - /* we ask for a non connectable maybe decodeable file handle */ + /* Encode a possibly decodeable/connectable file handle */ retval = exportfs_encode_fh(path->dentry, (struct fid *)handle->f_handle, &handle_dwords, fh_flags); @@ -109,15 +114,26 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, { struct path path; int lookup_flags; - int fh_flags; + int fh_flags = 0; int err; if (flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH | AT_HANDLE_FID | - AT_HANDLE_MNT_ID_UNIQUE)) + AT_HANDLE_MNT_ID_UNIQUE | AT_HANDLE_CONNECTABLE)) + return -EINVAL; + + /* + * AT_HANDLE_FID means there is no intention to decode file handle + * AT_HANDLE_CONNECTABLE means there is an intention to decode a + * connected fd (with known path), so these flags are conflicting. + */ + if (flag & AT_HANDLE_CONNECTABLE && flag & AT_HANDLE_FID) return -EINVAL; + else if (flag & AT_HANDLE_FID) + fh_flags |= EXPORT_FH_FID; + else if (flag & AT_HANDLE_CONNECTABLE) + fh_flags |= EXPORT_FH_CONNECTABLE; lookup_flags = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0; - fh_flags = (flag & AT_HANDLE_FID) ? EXPORT_FH_FID : 0; if (flag & AT_EMPTY_PATH) lookup_flags |= LOOKUP_EMPTY; err = user_path_at(dfd, name, lookup_flags, &path); diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index 87e2dec79fea..56ff2100e021 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -153,6 +153,7 @@ object identity and may not be usable with open_by_handle_at(2). */ #define AT_HANDLE_MNT_ID_UNIQUE 0x001 /* Return the u64 unique mount ID. */ +#define AT_HANDLE_CONNECTABLE 0x002 /* Request a connectable file handle */ #if defined(__KERNEL__) #define AT_GETATTR_NOSEC 0x80000000