From patchwork Thu Jan 23 16:45:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 1228466 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=MKYCy6Vp; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 483Wjh1ZJsz9sNF for ; Fri, 24 Jan 2020 05:57:28 +1100 (AEDT) Received: from localhost ([::1]:35188 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iuhfR-0006aO-QG for incoming@patchwork.ozlabs.org; Thu, 23 Jan 2020 13:57:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41457) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iufeA-0005E8-26 for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:47:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iufe8-0006fC-Jn for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:47:57 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:28100 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iufe8-0006f4-Gc for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:47:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579798076; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tKmIx2goe/8AH+0OLBD9B3fz9bJTXcfzHsQVtaOAxTc=; b=MKYCy6VpMC4kguFLwHKT9gy2b8Re1bT54CFF0IDb3xkk5ktuo+ArAWNxVaAKAvqcg1juYB huA2MbicSIPF4pPlxRavObxaD4QgytYuweApktpwKQHbkL4jVCjulNVeQdRH0t4T+FfogA vDTUNyyseO0MaY3tMqevSvBjyPjmzHQ= 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-350-eZ9t2gZjO7S9tRk58Z8pYg-1; Thu, 23 Jan 2020 11:47:54 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B6A347A0A9 for ; Thu, 23 Jan 2020 16:47:53 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-116-110.ams2.redhat.com [10.36.116.110]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1060019C69; Thu, 23 Jan 2020 16:47:52 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 054/108] virtiofsd: cap-ng helpers Date: Thu, 23 Jan 2020 16:45:36 +0000 Message-Id: <20200123164630.91498-55-dgilbert@redhat.com> In-Reply-To: <20200123164630.91498-1-dgilbert@redhat.com> References: <20200123164630.91498-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: eZ9t2gZjO7S9tRk58Z8pYg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: "Dr. David Alan Gilbert" libcap-ng reads /proc during capng_get_caps_process, and virtiofsd's sandboxing doesn't have /proc mounted; thus we have to do the caps read before we sandbox it and save/restore the state. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Daniel P. Berrangé Signed-off-by: Dr. David Alan Gilbert --- Makefile | 4 +- tools/virtiofsd/passthrough_ll.c | 72 ++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index ad400f36b2..6b4b075a92 100644 --- a/Makefile +++ b/Makefile @@ -327,7 +327,7 @@ HELPERS-y += vhost-user-gpu$(EXESUF) vhost-user-json-y += contrib/vhost-user-gpu/50-qemu-gpu.json endif -ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP),yy) +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP)$(CONFIG_LIBCAP_NG),yyy) HELPERS-y += virtiofsd$(EXESUF) vhost-user-json-y += tools/virtiofsd/50-qemu-virtiofsd.json endif @@ -675,7 +675,7 @@ rdmacm-mux$(EXESUF): $(rdmacm-mux-obj-y) $(COMMON_LDADDS) $(call LINK, $^) # relies on Linux-specific syscalls -ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP),yy) +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP)$(CONFIG_LIBCAP_NG),yyy) virtiofsd$(EXESUF): $(virtiofsd-obj-y) libvhost-user.a $(COMMON_LDADDS) $(call LINK, $^) endif diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index bd8925bd83..97e7c75667 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -39,6 +39,7 @@ #include "fuse_virtio.h" #include "fuse_lowlevel.h" #include +#include #include #include #include @@ -139,6 +140,13 @@ static const struct fuse_opt lo_opts[] = { static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n); +static struct { + pthread_mutex_t mutex; + void *saved; +} cap; +/* That we loaded cap-ng in the current thread from the saved */ +static __thread bool cap_loaded = 0; + static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st); static int is_dot_or_dotdot(const char *name) @@ -162,6 +170,37 @@ static struct lo_data *lo_data(fuse_req_t req) return (struct lo_data *)fuse_req_userdata(req); } +/* + * Load capng's state from our saved state if the current thread + * hadn't previously been loaded. + * returns 0 on success + */ +static int load_capng(void) +{ + if (!cap_loaded) { + pthread_mutex_lock(&cap.mutex); + capng_restore_state(&cap.saved); + /* + * restore_state free's the saved copy + * so make another. + */ + cap.saved = capng_save_state(); + if (!cap.saved) { + fuse_log(FUSE_LOG_ERR, "capng_save_state (thread)\n"); + return -EINVAL; + } + pthread_mutex_unlock(&cap.mutex); + + /* + * We want to use the loaded state for our pid, + * not the original + */ + capng_setpid(syscall(SYS_gettid)); + cap_loaded = true; + } + return 0; +} + static void lo_map_init(struct lo_map *map) { map->elems = NULL; @@ -2023,6 +2062,35 @@ static void setup_namespaces(struct lo_data *lo, struct fuse_session *se) } } +/* + * Capture the capability state, we'll need to restore this for individual + * threads later; see load_capng. + */ +static void setup_capng(void) +{ + /* Note this accesses /proc so has to happen before the sandbox */ + if (capng_get_caps_process()) { + fuse_log(FUSE_LOG_ERR, "capng_get_caps_process\n"); + exit(1); + } + pthread_mutex_init(&cap.mutex, NULL); + pthread_mutex_lock(&cap.mutex); + cap.saved = capng_save_state(); + if (!cap.saved) { + fuse_log(FUSE_LOG_ERR, "capng_save_state\n"); + exit(1); + } + pthread_mutex_unlock(&cap.mutex); +} + +static void cleanup_capng(void) +{ + free(cap.saved); + cap.saved = NULL; + pthread_mutex_destroy(&cap.mutex); +} + + /* * Make the source directory our root so symlinks cannot escape and no other * files are accessible. Assumes unshare(CLONE_NEWNS) was already called. @@ -2216,12 +2284,16 @@ int main(int argc, char *argv[]) fuse_daemonize(opts.foreground); + /* Must be before sandbox since it wants /proc */ + setup_capng(); + setup_sandbox(&lo, se); /* Block until ctrl+c or fusermount -u */ ret = virtio_loop(se); fuse_session_unmount(se); + cleanup_capng(); err_out3: fuse_remove_signal_handlers(se); err_out2: