From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49069) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dqFJS-0001CM-2J for qemu-devel@nongnu.org; Fri, 08 Sep 2017 05:11:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dqFJN-0002xc-6u for qemu-devel@nongnu.org; Fri, 08 Sep 2017 05:10:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53138) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dqFJM-0002wb-V8 for qemu-devel@nongnu.org; Fri, 08 Sep 2017 05:10:53 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 235B77E421 for ; Fri, 8 Sep 2017 09:10:52 +0000 (UTC) From: Eduardo Otubo Date: Fri, 8 Sep 2017 11:10:26 +0200 Message-Id: <20170908091027.9104-5-otubo@redhat.com> In-Reply-To: <20170908091027.9104-1-otubo@redhat.com> References: <20170908091027.9104-1-otubo@redhat.com> Subject: [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: thuth@redhat.com, "Daniel P . Berrange" 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 2bad16cafb..4c169febf8 100644 --- a/qemu-seccomp.c +++ b/qemu-seccomp.c @@ -79,6 +79,10 @@ 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 }, }; @@ -109,6 +113,14 @@ int seccomp_start(uint32_t seccomp_opts) } break; + case QEMU_SECCOMP_SET_SPAWN: + if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) { + break; + } else { + continue; + } + + break; default: break; } diff --git a/vl.c b/vl.c index 413cfe8504..0af137da17 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 */ } }, }; @@ -1081,6 +1085,18 @@ 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"); -- 2.13.5