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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42638 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kVyOQ-00013I-65 for qemu-devel@archiver.kernel.org; Fri, 23 Oct 2020 10:50:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47966) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kVyNp-0000dX-Cl for qemu-devel@nongnu.org; Fri, 23 Oct 2020 10:49:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:57575) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kVyNl-00047k-U1 for qemu-devel@nongnu.org; Fri, 23 Oct 2020 10:49:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603464567; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7LPFaYKMzIRya6rSxMVsiA60VXQwf73a7NurhLqpaVY=; b=hV8fWGDWiCipkS23X63lcylThgkRekh+u9b1IT0M9hbxttTaRsTFfskI3y4C5BtWi5N3Ut hD1YFWMz92n444ZTmACCXPRAmUewOPOChzm1yuhNutvaCmKjN3MVMLeEoVr3JQqA1ZZSbe 1d5i7CZza0Kv9epqqNxDVs24Et/rknY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-113-b72zFVTEOK2Cub2ZrvI3ag-1; Fri, 23 Oct 2020 10:49:26 -0400 X-MC-Unique: b72zFVTEOK2Cub2ZrvI3ag-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 00FB71018F81 for ; Fri, 23 Oct 2020 14:49:25 +0000 (UTC) Received: from work-vm (ovpn-113-212.ams2.redhat.com [10.36.113.212]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 22AB07D4E1; Fri, 23 Oct 2020 14:49:14 +0000 (UTC) Date: Fri, 23 Oct 2020 15:49:12 +0100 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [PATCH v3 3/5] tools/virtiofsd: xattr name mappings: Map server xattr names Message-ID: <20201023144912.GE3038@work-vm> References: <20201014180209.49299-1-dgilbert@redhat.com> <20201014180209.49299-4-dgilbert@redhat.com> <20201022161656.GD512900@redhat.com> MIME-Version: 1.0 In-Reply-To: <20201022161656.GD512900@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/23 01:44:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dinechin@redhat.com, virtio-fs@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > On Wed, Oct 14, 2020 at 07:02:07PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > Map xattr names coming from the server, i.e. the host filesystem; > > currently this is only from listxattr. > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > tools/virtiofsd/passthrough_ll.c | 89 ++++++++++++++++++++++++++++++++ > > 1 file changed, 89 insertions(+) > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 57ebe17ed6..8406a2ae86 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2220,6 +2220,43 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, > > } > > } > > > > + /* Shouldn't get here - rules should have an END_* - check parse_xattrmap */ > > + abort(); > > +} > > + > > +/* > > + * For use with listxattr where the server fs gives us a name and we may need > > + * to sanitize this for the client. > > + * Returns a pointer to the result in *out_name > > + * This is always the original string or the current string with some prefix > > + * removed; no reallocation is done. > > + * Returns 0 on success > > + * Can return -ENODATA to indicate the name should be dropped from the list. > > + */ > > +static int xattr_map_server(const struct lo_data *lo, const char *server_name, > > + const char **out_name) > > +{ > > + const XattrMapEntry *cur_entry; > > + const char *end; > > + > > + for (cur_entry = lo->xattr_map_list; ; cur_entry++) { > > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > > + (strstart(server_name, cur_entry->prepend, &end))) { > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { > > + return -ENODATA; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { > > + *out_name = server_name; > > + return 0; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { > > + /* Remove prefix */ > > + *out_name = end; > > + return 0; > > + } > > + } > > + } > > + > > /* Shouldn't get here - rules should have an END_* */ > > abort(); > > I am wondering why to put that restriction. If none of the rules match, > can't we just return as nothing has to be done. I always add a terminator in the parse as either a bad/ok, and was just enforcing it - but I've changed it to a return -ENODATA that's probably safer than the abort(). > > } > > @@ -2378,8 +2415,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > > if (ret == 0) { > > goto out; > > } > > + > > + if (lo->xattr_map_list) { > > + /* > > + * Map the names back, some attributes might be dropped, > > + * some shortened, but not increased, so we shouldn't > > + * run out of room. > > + */ > > + size_t out_index, in_index; > > + out_index = 0; > > + in_index = 0; > > + while (in_index < ret) { > > + const char *map_out; > > + char *in_ptr = value + in_index; > > + /* Length of current attribute name */ > > + size_t in_len = strlen(value + in_index) + 1; > > + > > + int mapret = xattr_map_server(lo, in_ptr, &map_out); > > + if (mapret != -ENODATA && mapret != 0) { > > + /* Shouldn't happen */ > > + saverr = -mapret; > > + goto out; > > + } > > + if (mapret == 0) { > > + /* Either unchanged, or truncated */ > > + size_t out_len; > > + if (map_out != in_ptr) { > > + /* +1 copies the NIL */ > > + out_len = strlen(map_out) + 1; > > + } else { > > + /* No change */ > > + out_len = in_len; > > + } > > + /* > > + * Move result along, may still be needed for an unchanged > > + * entry if a previous entry was changed. > > + */ > > + memmove(value + out_index, map_out, out_len); > > + > > + out_index += out_len; > > + } > > + in_index += in_len; > > + } > > + ret = out_index; > > + if (ret == 0) { > > + goto out; > > + } > > + } > > fuse_reply_buf(req, value, ret); > > } else { > > + /* > > + * xattrmap only ever shortens the result, > > + * so we don't need to do anything clever with the > > + * allocation length here. > > + */ > > fuse_reply_xattr(req, ret); > > Hmmm.., so this code returns the length of buffer which will fit xattrs. > So we will will changing the semantics a bit. Instead of returning > the exact size of buffer needed, we will be returning max size. I hope > its not a problem. Fixing it will be too expensive I guess. Right, although the semantics are fuzzy anyway since someone can come along and add/remove an xattr between the listxattr calls. Dave > Thanks > Vivek -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 23 Oct 2020 15:49:12 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20201023144912.GE3038@work-vm> References: <20201014180209.49299-1-dgilbert@redhat.com> <20201014180209.49299-4-dgilbert@redhat.com> <20201022161656.GD512900@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201022161656.GD512900@redhat.com> Subject: Re: [Virtio-fs] [PATCH v3 3/5] tools/virtiofsd: xattr name mappings: Map server xattr names List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vivek Goyal Cc: dinechin@redhat.com, virtio-fs@redhat.com, qemu-devel@nongnu.org * Vivek Goyal (vgoyal@redhat.com) wrote: > On Wed, Oct 14, 2020 at 07:02:07PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > Map xattr names coming from the server, i.e. the host filesystem; > > currently this is only from listxattr. > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > tools/virtiofsd/passthrough_ll.c | 89 ++++++++++++++++++++++++++++++++ > > 1 file changed, 89 insertions(+) > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 57ebe17ed6..8406a2ae86 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2220,6 +2220,43 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, > > } > > } > > > > + /* Shouldn't get here - rules should have an END_* - check parse_xattrmap */ > > + abort(); > > +} > > + > > +/* > > + * For use with listxattr where the server fs gives us a name and we may need > > + * to sanitize this for the client. > > + * Returns a pointer to the result in *out_name > > + * This is always the original string or the current string with some prefix > > + * removed; no reallocation is done. > > + * Returns 0 on success > > + * Can return -ENODATA to indicate the name should be dropped from the list. > > + */ > > +static int xattr_map_server(const struct lo_data *lo, const char *server_name, > > + const char **out_name) > > +{ > > + const XattrMapEntry *cur_entry; > > + const char *end; > > + > > + for (cur_entry = lo->xattr_map_list; ; cur_entry++) { > > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > > + (strstart(server_name, cur_entry->prepend, &end))) { > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { > > + return -ENODATA; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { > > + *out_name = server_name; > > + return 0; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { > > + /* Remove prefix */ > > + *out_name = end; > > + return 0; > > + } > > + } > > + } > > + > > /* Shouldn't get here - rules should have an END_* */ > > abort(); > > I am wondering why to put that restriction. If none of the rules match, > can't we just return as nothing has to be done. I always add a terminator in the parse as either a bad/ok, and was just enforcing it - but I've changed it to a return -ENODATA that's probably safer than the abort(). > > } > > @@ -2378,8 +2415,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > > if (ret == 0) { > > goto out; > > } > > + > > + if (lo->xattr_map_list) { > > + /* > > + * Map the names back, some attributes might be dropped, > > + * some shortened, but not increased, so we shouldn't > > + * run out of room. > > + */ > > + size_t out_index, in_index; > > + out_index = 0; > > + in_index = 0; > > + while (in_index < ret) { > > + const char *map_out; > > + char *in_ptr = value + in_index; > > + /* Length of current attribute name */ > > + size_t in_len = strlen(value + in_index) + 1; > > + > > + int mapret = xattr_map_server(lo, in_ptr, &map_out); > > + if (mapret != -ENODATA && mapret != 0) { > > + /* Shouldn't happen */ > > + saverr = -mapret; > > + goto out; > > + } > > + if (mapret == 0) { > > + /* Either unchanged, or truncated */ > > + size_t out_len; > > + if (map_out != in_ptr) { > > + /* +1 copies the NIL */ > > + out_len = strlen(map_out) + 1; > > + } else { > > + /* No change */ > > + out_len = in_len; > > + } > > + /* > > + * Move result along, may still be needed for an unchanged > > + * entry if a previous entry was changed. > > + */ > > + memmove(value + out_index, map_out, out_len); > > + > > + out_index += out_len; > > + } > > + in_index += in_len; > > + } > > + ret = out_index; > > + if (ret == 0) { > > + goto out; > > + } > > + } > > fuse_reply_buf(req, value, ret); > > } else { > > + /* > > + * xattrmap only ever shortens the result, > > + * so we don't need to do anything clever with the > > + * allocation length here. > > + */ > > fuse_reply_xattr(req, ret); > > Hmmm.., so this code returns the length of buffer which will fit xattrs. > So we will will changing the semantics a bit. Instead of returning > the exact size of buffer needed, we will be returning max size. I hope > its not a problem. Fixing it will be too expensive I guess. Right, although the semantics are fuzzy anyway since someone can come along and add/remove an xattr between the listxattr calls. Dave > Thanks > Vivek -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK