From patchwork Sat Feb 25 03:21:48 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Drewry X-Patchwork-Id: 143011 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 970BEB6FAF for ; Sat, 25 Feb 2012 14:23:08 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932288Ab2BYDXA (ORCPT ); Fri, 24 Feb 2012 22:23:00 -0500 Received: from mail-gx0-f174.google.com ([209.85.161.174]:60548 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932363Ab2BYDW5 (ORCPT ); Fri, 24 Feb 2012 22:22:57 -0500 Received: by mail-gx0-f174.google.com with SMTP id h1so1475925ggn.19 for ; Fri, 24 Feb 2012 19:22:57 -0800 (PST) Received-SPF: pass (google.com: domain of wad@chromium.org designates 10.236.72.170 as permitted sender) client-ip=10.236.72.170; Authentication-Results: mr.google.com; spf=pass (google.com: domain of wad@chromium.org designates 10.236.72.170 as permitted sender) smtp.mail=wad@chromium.org; dkim=pass header.i=wad@chromium.org Received: from mr.google.com ([10.236.72.170]) by 10.236.72.170 with SMTP id t30mr9495251yhd.101.1330140177176 (num_hops = 1); Fri, 24 Feb 2012 19:22:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references; bh=MNQzIgLYMuaKgpAfT+bafpGJmsLL/o5qMRLgB+SEa18=; b=S7x7rJmBXB+ruZhokd2t6uzWP2Foj97FkxEw2WKHXIbbqPti3a/nuBBrVDVJpewuXe gDXJQPxDv8qPSYq7IIwp84lGBK7YfYixczjiROuoMNepFTmWJSp0vBikhd7zC6eA5F+4 oLG3q1iadB3ps5e3k5jJUCd1alX+qHSzJdTLI= MIME-Version: 1.0 Received: by 10.236.72.170 with SMTP id t30mr7153108yhd.101.1330140176506; Fri, 24 Feb 2012 19:22:56 -0800 (PST) Received: from localhost.localdomain (173-164-30-65-Nashville.hfc.comcastbusiness.net. [173.164.30.65]) by mx.google.com with ESMTPS id n12sm17591629yhe.10.2012.02.24.19.22.54 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 24 Feb 2012 19:22:55 -0800 (PST) From: Will Drewry To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com, netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de, davem@davemloft.net, hpa@zytor.com, mingo@redhat.com, oleg@redhat.com, peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu, eparis@redhat.com, serge.hallyn@canonical.com, djm@mindrot.org, scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com, markus@chromium.org, coreyb@linux.vnet.ibm.com, keescook@chromium.org, Will Drewry Subject: [PATCH v11 09/12] seccomp: Add SECCOMP_RET_TRAP Date: Fri, 24 Feb 2012 21:21:48 -0600 Message-Id: <1330140111-17201-9-git-send-email-wad@chromium.org> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1330140111-17201-1-git-send-email-wad@chromium.org> References: <1330140111-17201-1-git-send-email-wad@chromium.org> X-Gm-Message-State: ALoCoQml4Z4YJP6H7j2i2Z3Mp66o9THg5WeL4Z/r7X/5jBxOx9t4dyM/S/6UMNTy/WJu5drT1WDK Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Adds a new return value to seccomp filters that triggers a SIGSYS to be delivered with the new SYS_SECCOMP si_code. This allows in-process system call emulation, including just specifying an errno or cleanly dumping core, rather than just dying. v11: - clarify the comment (indan@nul.nu) - s/sigtrap/sigsys v10: - use SIGSYS, syscall_get_arch, updates arch/Kconfig note suggested-by (though original suggestion had other behaviors) v9: - changes to SIGILL v8: - clean up based on changes to dependent patches v7: - introduction Suggested-by: Markus Gutschke Suggested-by: Julien Tinnes Signed-off-by: Will Drewry --- arch/Kconfig | 14 +++++++++----- include/asm-generic/siginfo.h | 2 +- include/linux/seccomp.h | 1 + kernel/seccomp.c | 28 ++++++++++++++++++++++++++++ 4 files changed, 39 insertions(+), 6 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index dd4e067..d92a78e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -202,11 +202,15 @@ config HAVE_CMPXCHG_DOUBLE config HAVE_ARCH_SECCOMP_FILTER bool help - This symbol should be selected by an architecure if it provides - asm/syscall.h, specifically syscall_get_arguments(), - syscall_get_arch(), and syscall_set_return_value(). Additionally, - its system call entry path must respect a return value of -1 from - __secure_computing_int() and/or secure_computing(). + This symbol should be selected by an architecure if it provides: + asm/syscall.h: + - syscall_get_arch() + - syscall_get_arguments() + - syscall_rollback() + - syscall_set_return_value() + SIGSYS siginfo_t support must be implemented. + __secure_computing_int()/secure_computing()'s return value must be + checked, with -1 resulting in the syscall being skipped. config SECCOMP_FILTER def_bool y diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h index 31306f5..af5d035 100644 --- a/include/asm-generic/siginfo.h +++ b/include/asm-generic/siginfo.h @@ -93,7 +93,7 @@ typedef struct siginfo { /* SIGSYS */ struct { - void __user *_call_addr; /* calling insn */ + void __user *_call_addr; /* calling user insn */ int _syscall; /* triggering system call number */ unsigned int _arch; /* AUDIT_ARCH_* of syscall */ } _sigsys; diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 93c2d98..b44d038 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -19,6 +19,7 @@ * selects the least permissive choice. */ #define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */ +#define SECCOMP_RET_TRAP 0x00020000U /* disallow and force a SIGSYS */ #define SECCOMP_RET_ERRNO 0x00030000U /* returns an errno */ #define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */ diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 3b3a16e..d2e173e 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -272,6 +272,26 @@ void copy_seccomp(struct seccomp *child, const struct seccomp *parent) /* Other fields are handled by dup_task_struct. */ child->filter = get_seccomp_filter(parent->filter); } + +/** + * seccomp_send_sigsys - signals the task to allow in-process syscall emulation + * @syscall: syscall number to send to userland + * @reason: filter-supplied reason code to send to userland (via si_errno) + * + * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. + */ +static void seccomp_send_sigsys(int syscall, int reason) +{ + struct siginfo info; + memset(&info, 0, sizeof(info)); + info.si_signo = SIGSYS; + info.si_code = SYS_SECCOMP; + info.si_call_addr = (void __user *)KSTK_EIP(current); + info.si_errno = reason; + info.si_arch = syscall_get_arch(current, task_pt_regs(current)); + info.si_syscall = syscall; + force_sig_info(SIGSYS, &info, current); +} #endif /* CONFIG_SECCOMP_FILTER */ /* @@ -326,6 +346,14 @@ int __secure_computing_int(int this_syscall) -(action & SECCOMP_RET_DATA), 0); return -1; + case SECCOMP_RET_TRAP: { + int reason_code = action & SECCOMP_RET_DATA; + /* Show the handler the original registers. */ + syscall_rollback(current, task_pt_regs(current)); + /* Let the filter pass back 16 bits of data. */ + seccomp_send_sigsys(this_syscall, reason_code); + return -1; + } case SECCOMP_RET_ALLOW: return 0; case SECCOMP_RET_KILL: