From patchwork Thu Jan 23 11:57:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 1227984 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=PI/HTKHL; 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 483Ns53M7Tz9sSQ for ; Fri, 24 Jan 2020 00:48:24 +1100 (AEDT) Received: from localhost ([::1]:57280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iucqM-0002wf-9K for incoming@patchwork.ozlabs.org; Thu, 23 Jan 2020 08:48:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40842) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iub9P-0002oS-Iy for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iub9M-0005PF-VC for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:54 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:36188 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iub9M-0005P1-RY for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579780792; 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=KK/7qgjHzoRF+pgAqQJZ36ORUn7lwgLqQgxeveozNWk=; b=PI/HTKHL8ZqE4eCqqwHa+vIpzNzgYMLZBTAfSXlR8J4kIttlleKQIlZ4xCpqFTnAr1y5ar HwtigEIqvBJsQoei8LtAp47CTiAiVybggbb97FhqLadZCvd5U7huOUaA/byLhchRtUvvmw w4Tu7gjd0rEKbQ73QQ5rRvGW9LH8+UI= 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-217-szrA5WPTMtW_Oe-8aLLPpQ-1; Thu, 23 Jan 2020 06:59:49 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E96411800D48 for ; Thu, 23 Jan 2020 11:59:48 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id 42F451CB; Thu, 23 Jan 2020 11:59:48 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 052/111] virtiofsd: add seccomp whitelist Date: Thu, 23 Jan 2020 11:57:42 +0000 Message-Id: <20200123115841.138849-53-dgilbert@redhat.com> In-Reply-To: <20200123115841.138849-1-dgilbert@redhat.com> References: <20200123115841.138849-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: szrA5WPTMtW_Oe-8aLLPpQ-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: 207.211.31.120 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: Stefan Hajnoczi Only allow system calls that are needed by virtiofsd. All other system calls cause SIGSYS to be directed at the thread and the process will coredump. Restricting system calls reduces the kernel attack surface and limits what the process can do when compromised. Signed-off-by: Stefan Hajnoczi with additional entries by: Signed-off-by: Ganesh Maharaj Mahalingam Signed-off-by: Masayoshi Mizuma Signed-off-by: Misono Tomohiro Signed-off-by: piaojun Signed-off-by: Vivek Goyal Signed-off-by: Eric Ren Signed-off-by: Dr. David Alan Gilbert --- Makefile | 5 +- tools/virtiofsd/Makefile.objs | 5 +- tools/virtiofsd/passthrough_ll.c | 2 + tools/virtiofsd/seccomp.c | 151 +++++++++++++++++++++++++++++++ tools/virtiofsd/seccomp.h | 14 +++ 5 files changed, 174 insertions(+), 3 deletions(-) create mode 100644 tools/virtiofsd/seccomp.c create mode 100644 tools/virtiofsd/seccomp.h diff --git a/Makefile b/Makefile index 2f81271ee7..ad400f36b2 100644 --- a/Makefile +++ b/Makefile @@ -327,7 +327,7 @@ HELPERS-y += vhost-user-gpu$(EXESUF) vhost-user-json-y += contrib/vhost-user-gpu/50-qemu-gpu.json endif -ifdef CONFIG_LINUX +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP),yy) HELPERS-y += virtiofsd$(EXESUF) vhost-user-json-y += tools/virtiofsd/50-qemu-virtiofsd.json endif @@ -674,7 +674,8 @@ rdmacm-mux$(EXESUF): LIBS += "-libumad" rdmacm-mux$(EXESUF): $(rdmacm-mux-obj-y) $(COMMON_LDADDS) $(call LINK, $^) -ifdef CONFIG_LINUX # relies on Linux-specific syscalls +# relies on Linux-specific syscalls +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP),yy) virtiofsd$(EXESUF): $(virtiofsd-obj-y) libvhost-user.a $(COMMON_LDADDS) $(call LINK, $^) endif diff --git a/tools/virtiofsd/Makefile.objs b/tools/virtiofsd/Makefile.objs index 45a807500d..076f667e46 100644 --- a/tools/virtiofsd/Makefile.objs +++ b/tools/virtiofsd/Makefile.objs @@ -5,5 +5,8 @@ virtiofsd-obj-y = buffer.o \ fuse_signals.o \ fuse_virtio.o \ helper.o \ - passthrough_ll.o + passthrough_ll.o \ + seccomp.o +seccomp.o-cflags := $(SECCOMP_CFLAGS) +seccomp.o-libs := $(SECCOMP_LIBS) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 0947d14e5b..bd8925bd83 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -59,6 +59,7 @@ #include #include "passthrough_helpers.h" +#include "seccomp.h" struct lo_map_elem { union { @@ -2091,6 +2092,7 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se) { setup_namespaces(lo, se); setup_mounts(lo->source); + setup_seccomp(); } int main(int argc, char *argv[]) diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c new file mode 100644 index 0000000000..691fb63dea --- /dev/null +++ b/tools/virtiofsd/seccomp.c @@ -0,0 +1,151 @@ +/* + * Seccomp sandboxing for virtiofsd + * + * Copyright (C) 2019 Red Hat, Inc. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "qemu/osdep.h" +#include "seccomp.h" +#include "fuse_i.h" +#include "fuse_log.h" +#include +#include +#include +#include + +/* Bodge for libseccomp 2.4.2 which broke ppoll */ +#if !defined(__SNR_ppoll) && defined(__SNR_brk) +#ifdef __NR_ppoll +#define __SNR_ppoll __NR_ppoll +#else +#define __SNR_ppoll __PNR_ppoll +#endif +#endif + +static const int syscall_whitelist[] = { + /* TODO ireg sem*() syscalls */ + SCMP_SYS(brk), + SCMP_SYS(capget), /* For CAP_FSETID */ + SCMP_SYS(capset), + SCMP_SYS(clock_gettime), + SCMP_SYS(clone), +#ifdef __NR_clone3 + SCMP_SYS(clone3), +#endif + SCMP_SYS(close), + SCMP_SYS(copy_file_range), + SCMP_SYS(dup), + SCMP_SYS(eventfd2), + SCMP_SYS(exit), + SCMP_SYS(exit_group), + SCMP_SYS(fallocate), + SCMP_SYS(fchmodat), + SCMP_SYS(fchownat), + SCMP_SYS(fcntl), + SCMP_SYS(fdatasync), + SCMP_SYS(fgetxattr), + SCMP_SYS(flistxattr), + SCMP_SYS(flock), + SCMP_SYS(fremovexattr), + SCMP_SYS(fsetxattr), + SCMP_SYS(fstat), + SCMP_SYS(fstatfs), + SCMP_SYS(fsync), + SCMP_SYS(ftruncate), + SCMP_SYS(futex), + SCMP_SYS(getdents), + SCMP_SYS(getdents64), + SCMP_SYS(getegid), + SCMP_SYS(geteuid), + SCMP_SYS(getpid), + SCMP_SYS(gettid), + SCMP_SYS(gettimeofday), + SCMP_SYS(linkat), + SCMP_SYS(lseek), + SCMP_SYS(madvise), + SCMP_SYS(mkdirat), + SCMP_SYS(mknodat), + SCMP_SYS(mmap), + SCMP_SYS(mprotect), + SCMP_SYS(mremap), + SCMP_SYS(munmap), + SCMP_SYS(newfstatat), + SCMP_SYS(open), + SCMP_SYS(openat), + SCMP_SYS(ppoll), + SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */ + SCMP_SYS(preadv), + SCMP_SYS(pread64), + SCMP_SYS(pwritev), + SCMP_SYS(pwrite64), + SCMP_SYS(read), + SCMP_SYS(readlinkat), + SCMP_SYS(recvmsg), + SCMP_SYS(renameat), + SCMP_SYS(renameat2), + SCMP_SYS(rt_sigaction), + SCMP_SYS(rt_sigprocmask), + SCMP_SYS(rt_sigreturn), + SCMP_SYS(sendmsg), + SCMP_SYS(setresgid), + SCMP_SYS(setresuid), +#ifdef __NR_setresgid32 + SCMP_SYS(setresgid32), +#endif +#ifdef __NR_setresuid32 + SCMP_SYS(setresuid32), +#endif + SCMP_SYS(set_robust_list), + SCMP_SYS(symlinkat), + SCMP_SYS(time), /* Rarely needed, except on static builds */ + SCMP_SYS(tgkill), + SCMP_SYS(unlinkat), + SCMP_SYS(utimensat), + SCMP_SYS(write), + SCMP_SYS(writev), +}; + +void setup_seccomp(void) +{ + scmp_filter_ctx ctx; + size_t i; + +#ifdef SCMP_ACT_KILL_PROCESS + ctx = seccomp_init(SCMP_ACT_KILL_PROCESS); + /* Handle a newer libseccomp but an older kernel */ + if (!ctx && errno == EOPNOTSUPP) { + ctx = seccomp_init(SCMP_ACT_TRAP); + } +#else + ctx = seccomp_init(SCMP_ACT_TRAP); +#endif + if (!ctx) { + fuse_log(FUSE_LOG_ERR, "seccomp_init() failed\n"); + exit(1); + } + + for (i = 0; i < G_N_ELEMENTS(syscall_whitelist); i++) { + if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, + syscall_whitelist[i], 0) != 0) { + fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d", + syscall_whitelist[i]); + exit(1); + } + } + + /* libvhost-user calls this for post-copy migration, we don't need it */ + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOSYS), + SCMP_SYS(userfaultfd), 0) != 0) { + fuse_log(FUSE_LOG_ERR, "seccomp_rule_add userfaultfd failed\n"); + exit(1); + } + + if (seccomp_load(ctx) < 0) { + fuse_log(FUSE_LOG_ERR, "seccomp_load() failed\n"); + exit(1); + } + + seccomp_release(ctx); +} diff --git a/tools/virtiofsd/seccomp.h b/tools/virtiofsd/seccomp.h new file mode 100644 index 0000000000..86bce72652 --- /dev/null +++ b/tools/virtiofsd/seccomp.h @@ -0,0 +1,14 @@ +/* + * Seccomp sandboxing for virtiofsd + * + * Copyright (C) 2019 Red Hat, Inc. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#ifndef VIRTIOFSD_SECCOMP_H +#define VIRTIOFSD_SECCOMP_H + +void setup_seccomp(void); + +#endif /* VIRTIOFSD_SECCOMP_H */