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Fri, 23 Oct 2020 16:58:30 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-113-212.ams2.redhat.com [10.36.113.212]) by smtp.corp.redhat.com (Postfix) with ESMTP id C628E10013D7; Fri, 23 Oct 2020 16:58:28 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com, dinechin@redhat.com, virtio-fs@redhat.com Subject: [PATCH v4 3/5] tools/virtiofsd: xattr name mappings: Map server xattr names Date: Fri, 23 Oct 2020 17:58:10 +0100 Message-Id: <20201023165812.36028-4-dgilbert@redhat.com> In-Reply-To: <20201023165812.36028-1-dgilbert@redhat.com> References: <20201023165812.36028-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 Reviewed-by: Stefan Hajnoczi --- tools/virtiofsd/passthrough_ll.c | 90 ++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index ec3ef7b50d..57f584ee49 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2217,6 +2217,44 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, return -EPERM; } +/* + * 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) +{ + size_t i; + const char *end; + + for (i = 0; i < lo->xattr_map_nentries; i++) { + const XattrMapEntry *cur_entry = lo->xattr_map_list + i; + + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && + (strstart(server_name, cur_entry->prepend, &end))) { + if (cur_entry->flags & XATTR_MAP_FLAG_BAD) { + return -ENODATA; + } + if (cur_entry->flags & XATTR_MAP_FLAG_OK) { + *out_name = server_name; + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + /* Remove prefix */ + *out_name = end; + return 0; + } + } + } + + return -ENODATA; +} + static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { @@ -2371,8 +2409,60 @@ 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); } out_free: