From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754003AbbL2UrN (ORCPT ); Tue, 29 Dec 2015 15:47:13 -0500 Received: from 8.mo3.mail-out.ovh.net ([87.98.172.249]:37232 "EHLO 8.mo3.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753613AbbL2UrL (ORCPT ); Tue, 29 Dec 2015 15:47:11 -0500 From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Jeff Dike , Richard Weinberger , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, Kees Cook , Andy Lutomirski , Will Drewry , Shuah Khan , Chris Metcalf , Michael Ellerman , Andrew Morton , James Hogan , Thomas Meyer , Nicolas Iooss , Anton Ivanov , user-mode-linux-devel@lists.sourceforge.net, Meredydd Luff , David Drysdale Subject: [PATCH v3 4/4] um: Add seccomp support Date: Tue, 29 Dec 2015 21:35:47 +0100 Message-Id: <1451421347-9468-5-git-send-email-mic@digikod.net> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1451421347-9468-1-git-send-email-mic@digikod.net> References: <1451421347-9468-1-git-send-email-mic@digikod.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 17349836090416081177 X-Ovh-Remote: 94.23.54.103 (ns3096276.ip-94-23-54.eu) X-Ovh-Local: 213.186.33.20 (ns0.ovh.net) X-OVH-SPAMSTATE: OK X-OVH-SPAMSCORE: -100 X-OVH-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeekiedrheekucetufdoteggodftvfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeekiedrheekgddufeekucetufdoteggodftvfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This brings SECCOMP_MODE_STRICT and SECCOMP_MODE_FILTER support through prctl(2) and seccomp(2) to User-mode Linux for i386 and x86_64 subarchitectures. secure_computing() is called first in handle_syscall() so that the syscall emulation will be aborted quickly if matching a seccomp rule. This is inspired from Meredydd Luff's patch (https://gerrit.chromium.org/gerrit/21425). Signed-off-by: Mickaël Salaün Cc: Jeff Dike Cc: Richard Weinberger Cc: Ingo Molnar Cc: Kees Cook Cc: Andy Lutomirski Cc: Will Drewry Cc: Chris Metcalf Cc: Michael Ellerman Cc: James Hogan Cc: Meredydd Luff Cc: David Drysdale --- .../features/seccomp/seccomp-filter/arch-support.txt | 2 +- arch/um/Kconfig.common | 1 + arch/um/Kconfig.um | 16 ++++++++++++++++ arch/um/include/asm/thread_info.h | 2 ++ arch/um/kernel/skas/syscall.c | 5 +++++ 5 files changed, 25 insertions(+), 1 deletion(-) diff --git a/Documentation/features/seccomp/seccomp-filter/arch-support.txt b/Documentation/features/seccomp/seccomp-filter/arch-support.txt index 76d39d66a5d7..4f66ec133951 100644 --- a/Documentation/features/seccomp/seccomp-filter/arch-support.txt +++ b/Documentation/features/seccomp/seccomp-filter/arch-support.txt @@ -33,7 +33,7 @@ | sh: | TODO | | sparc: | TODO | | tile: | ok | - | um: | TODO | + | um: | ok | | unicore32: | TODO | | x86: | ok | | xtensa: | TODO | diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common index d195a87ca542..cc0013475444 100644 --- a/arch/um/Kconfig.common +++ b/arch/um/Kconfig.common @@ -2,6 +2,7 @@ config UML bool default y select HAVE_ARCH_AUDITSYSCALL + select HAVE_ARCH_SECCOMP_FILTER select HAVE_UID16 select HAVE_FUTEX_CMPXCHG if FUTEX select GENERIC_IRQ_SHOW diff --git a/arch/um/Kconfig.um b/arch/um/Kconfig.um index 28a9885e3a37..4b2ed5858b2e 100644 --- a/arch/um/Kconfig.um +++ b/arch/um/Kconfig.um @@ -104,3 +104,19 @@ config PGTABLE_LEVELS int default 3 if 3_LEVEL_PGTABLES default 2 + +config SECCOMP + def_bool y + prompt "Enable seccomp to safely compute untrusted bytecode" + ---help--- + This kernel feature is useful for number crunching applications + that may need to compute untrusted bytecode during their + execution. By using pipes or other transports made available to + the process as file descriptors supporting the read/write + syscalls, it's possible to isolate those applications in + their own address space using seccomp. Once seccomp is + enabled via prctl(PR_SET_SECCOMP), it cannot be disabled + and the task is only allowed to execute a few safe syscalls + defined by each seccomp mode. + + If unsure, say Y. diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h index 53968aaf76f9..053baff03674 100644 --- a/arch/um/include/asm/thread_info.h +++ b/arch/um/include/asm/thread_info.h @@ -62,11 +62,13 @@ static inline struct thread_info *current_thread_info(void) #define TIF_SYSCALL_AUDIT 6 #define TIF_RESTORE_SIGMASK 7 #define TIF_NOTIFY_RESUME 8 +#define TIF_SECCOMP 9 /* secure computing */ #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_MEMDIE (1 << TIF_MEMDIE) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) +#define _TIF_SECCOMP (1 << TIF_SECCOMP) #endif diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c index 6cadce761bcf..48b0dcbd87be 100644 --- a/arch/um/kernel/skas/syscall.c +++ b/arch/um/kernel/skas/syscall.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -19,6 +20,10 @@ void handle_syscall(struct uml_pt_regs *r) UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp); PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS); + /* Do the secure computing check first; failures should be fast. */ + if (secure_computing() == -1) + return; + if (syscall_trace_enter(regs)) goto out; -- 2.6.4