From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58210) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dqJ6n-0007qr-FH for qemu-devel@nongnu.org; Fri, 08 Sep 2017 09:14:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dqJ6h-0008LH-Ah for qemu-devel@nongnu.org; Fri, 08 Sep 2017 09:14:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35558) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dqJ6h-0008Jc-18 for qemu-devel@nongnu.org; Fri, 08 Sep 2017 09:14:03 -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 2C4914A703 for ; Fri, 8 Sep 2017 13:14:02 +0000 (UTC) References: <20170908114407.25906-1-otubo@redhat.com> <20170908114407.25906-5-otubo@redhat.com> From: Thomas Huth Message-ID: <5d183826-dc0c-6d52-9ba5-3c8598f38cdf@redhat.com> Date: Fri, 8 Sep 2017 15:13:56 +0200 MIME-Version: 1.0 In-Reply-To: <20170908114407.25906-5-otubo@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv6 4/5] seccomp: add spawn argument to command line List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Otubo , qemu-devel@nongnu.org On 08.09.2017 13:44, Eduardo Otubo wrote: > 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 | 4 ++++ > vl.c | 16 ++++++++++++++++ > 4 files changed, 28 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 978d66bd28..f3878a5e29 100644 > --- a/qemu-seccomp.c > +++ b/qemu-seccomp.c > @@ -78,6 +78,10 @@ static const struct QemuSeccompSyscall blacklist[] = { > { SCMP_SYS(setresgid), QEMU_SECCOMP_SET_PRIVILEGED }, > { SCMP_SYS(setfsuid), QEMU_SECCOMP_SET_PRIVILEGED }, > { SCMP_SYS(setfsgid), QEMU_SECCOMP_SET_PRIVILEGED }, > + /* spawn */ > + { SCMP_SYS(fork), QEMU_SECCOMP_SET_SPAWN }, > + { SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN }, > + { SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN }, > }; > > > diff --git a/vl.c b/vl.c > index ff3b5c766a..369e3411b1 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 */ } > }, > }; > @@ -1082,6 +1086,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp) > } > } > > + value = qemu_opt_get(opts, "spawn"); > + if (value) { > + if (g_str_equal(value, "deny")) { > + seccomp_opts |= QEMU_SECCOMP_SET_SPAWN; > + } else if (g_str_equal(value, "allow")) { > + /* 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"); Reviewed-by: Thomas Huth