From patchwork Fri Sep 1 10:58:16 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eduardo Otubo X-Patchwork-Id: 9933911 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 591326016C for ; Fri, 1 Sep 2017 11:02:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6527E2856F for ; Fri, 1 Sep 2017 11:02:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5A469285D1; Fri, 1 Sep 2017 11:02:26 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id EAB382856F for ; Fri, 1 Sep 2017 11:02:25 +0000 (UTC) Received: from localhost ([::1]:35186 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dnjiT-0002HG-0M for patchwork-qemu-devel@patchwork.kernel.org; Fri, 01 Sep 2017 07:02:25 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51346) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dnjfC-0000Lj-8H for qemu-devel@nongnu.org; Fri, 01 Sep 2017 06:59:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dnjf2-0001LG-Pk for qemu-devel@nongnu.org; Fri, 01 Sep 2017 06:59:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56842) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dnjf2-0001KW-Gm for qemu-devel@nongnu.org; Fri, 01 Sep 2017 06:58:52 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6A91961483 for ; Fri, 1 Sep 2017 10:58:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 6A91961483 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=otubo@redhat.com Received: from vader.redhat.com (ovpn-117-156.ams2.redhat.com [10.36.117.156]) by smtp.corp.redhat.com (Postfix) with ESMTP id DAD2D7EBC7; Fri, 1 Sep 2017 10:58:46 +0000 (UTC) From: Eduardo Otubo To: qemu-devel@nongnu.org Date: Fri, 1 Sep 2017 12:58:16 +0200 Message-Id: <20170901105818.31956-5-otubo@redhat.com> In-Reply-To: <20170901105818.31956-1-otubo@redhat.com> References: <20170901105818.31956-1-otubo@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 01 Sep 2017 10:58:51 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCHv4 4/6] seccomp: add spawn argument to command line X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thuth@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP This patch adds [,spawn=deny] argument to `-sandbox on' option. It blacklists fork and execve system calls, avoiding Qemu to spawn new threads or processes. Signed-off-by: Eduardo Otubo --- include/sysemu/seccomp.h | 1 + qemu-options.hx | 9 +++++++-- qemu-seccomp.c | 12 ++++++++++++ vl.c | 16 ++++++++++++++++ 4 files changed, 36 insertions(+), 2 deletions(-) diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h index 4a9e63c7cd..3ab5fc4f61 100644 --- a/include/sysemu/seccomp.h +++ b/include/sysemu/seccomp.h @@ -18,6 +18,7 @@ #define QEMU_SECCOMP_SET_DEFAULT (1 << 0) #define QEMU_SECCOMP_SET_OBSOLETE (1 << 1) #define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2) +#define QEMU_SECCOMP_SET_SPAWN (1 << 3) #include diff --git a/qemu-options.hx b/qemu-options.hx index 5c1b163fb5..2b04b9f170 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4018,6 +4018,7 @@ ETEXI DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ + " [,spawn=allow|deny]\n" \ " Enable seccomp mode 2 system call filter (default 'off').\n" \ " use 'obsolete' to allow obsolete system calls that are provided\n" \ " by the kernel, but typically no longer used by modern\n" \ @@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \ " its privileges by blacklisting all set*uid|gid system calls.\n" \ " The value 'children' will deny set*uid|gid system calls for\n" \ - " main QEMU process but will allow forks and execves to run unprivileged\n", + " main QEMU process but will allow forks and execves to run unprivileged\n" \ + " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ + " blacklisting *fork and execve\n", QEMU_ARCH_ALL) STEXI -@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}] +@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}] @findex -sandbox Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will disable it. The default is 'off'. @@ -4037,6 +4040,8 @@ disable it. The default is 'off'. Enable Obsolete system calls @item elevateprivileges=@var{string} Disable set*uid|gid system calls +@item spawn=@var{string} +Disable *fork and execve @end table ETEXI diff --git a/qemu-seccomp.c b/qemu-seccomp.c index 16c8c20132..51754ace71 100644 --- a/qemu-seccomp.c +++ b/qemu-seccomp.c @@ -67,6 +67,10 @@ static const struct QemuSeccompSyscall blacklist[] = { { SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED }, { SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED }, { SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED }, + /* spawn */ + { SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN }, + { SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN }, + { SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN }, }; @@ -100,6 +104,14 @@ int seccomp_start(uint32_t seccomp_opts) } break; + case QEMU_SECCOMP_SET_SPAWN: + if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) { + goto add_syscall; + } else { + continue; + } + + break; default: goto add_syscall; } diff --git a/vl.c b/vl.c index 1d44b05772..8e6b252f8f 100644 --- a/vl.c +++ b/vl.c @@ -280,6 +280,10 @@ static QemuOptsList qemu_sandbox_opts = { .name = "elevateprivileges", .type = QEMU_OPT_STRING, }, + { + .name = "spawn", + .type = QEMU_OPT_STRING, + }, { /* end of list */ } }, }; @@ -1079,6 +1083,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp) } } + value = qemu_opt_get(opts, "spawn"); + if (value) { + if (strcmp(value, "deny") == 0) { + seccomp_opts |= QEMU_SECCOMP_SET_SPAWN; + } else if (strcmp(value, "allow") == 0) { + /* default value */ + } else { + error_report("invalid argument for spawn"); + return -1; + } + } + if (seccomp_start(seccomp_opts) < 0) { error_report("failed to install seccomp syscall filter " "in the kernel");