Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755898Ab2BPVM0 (ORCPT ); Thu, 16 Feb 2012 16:12:26 -0500 Received: from mail-gx0-f174.google.com ([209.85.161.174]:62256 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753675Ab2BPVMX (ORCPT ); Thu, 16 Feb 2012 16:12:23 -0500 MIME-Version: 1.0 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, keescook@chromium.org, Will Drewry Subject: [PATCH v9 5/8] seccomp: Add SECCOMP_RET_TRAP Date: Thu, 16 Feb 2012 15:11:45 -0600 Message-Id: <1329426706-26562-1-git-send-email-wad@chromium.org> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3857 Lines: 110 Adds a new return value to seccomp filters that triggers a SIGILL to be delivered with the new ILL_SECCOMP si_code. This allows in-process system call emulation, including just specifying an errno or cleanly dumping core, rather than just dying. It also avoids interfering with normal debugger operation (injecting SIGTRAPs). v9: - changes to SIGILL (markus@chromium.org) v8: - clean up based on changes to dependent patches v7: - introduction Signed-off-by: Will Drewry --- arch/Kconfig | 8 ++++---- include/asm-generic/siginfo.h | 3 ++- include/linux/seccomp.h | 1 + kernel/seccomp.c | 20 ++++++++++++++++++++ 4 files changed, 27 insertions(+), 5 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 3f3052b..a01c151 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -203,10 +203,10 @@ 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() 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(). + asm/syscall.h, specifically syscall_get_arguments(), + syscall_set_return_value(), and syscall_rollback(). + Additionally, its system call entry path must respect a return + value of -1 from __secure_computing_int() and/or secure_computing(). config SECCOMP_FILTER def_bool y diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h index 0dd4e87..e565662 100644 --- a/include/asm-generic/siginfo.h +++ b/include/asm-generic/siginfo.h @@ -166,7 +166,8 @@ typedef struct siginfo { #define ILL_PRVREG (__SI_FAULT|6) /* privileged register */ #define ILL_COPROC (__SI_FAULT|7) /* coprocessor error */ #define ILL_BADSTK (__SI_FAULT|8) /* internal stack error */ -#define NSIGILL 8 +#define ILL_SECCOMP (__SI_FAULT|9) /* illegal syscall via seccomp */ +#define NSIGILL 9 /* * SIGFPE si_codes diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 879ece2..1be562f 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 send sigtrap */ #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 55d000d..a7b6510 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -290,6 +290,21 @@ void copy_seccomp(struct seccomp *child, child->mode = prev->mode; child->filter = get_seccomp_filter(prev->filter); } + +/** + * seccomp_send_sigill - signals the task to allow in-process syscall emulation + * + * Forces a SIGILL with si_code of ILL_SECCOMP. + */ +static void seccomp_send_sigill(void) +{ + struct siginfo info; + memset(&info, 0, sizeof(info)); + info.si_signo = SIGILL; + info.si_code = ILL_SECCOMP; + info.si_addr = (void __user *)KSTK_EIP(current); + force_sig_info(SIGILL, &info, current); +} #endif /* CONFIG_SECCOMP_FILTER */ /* @@ -343,6 +358,11 @@ int __secure_computing_int(int this_syscall) -(action & SECCOMP_RET_DATA), 0); return -1; + case SECCOMP_RET_TRAP: + /* Show the handler the original registers. */ + syscall_rollback(current, task_pt_regs(current)); + seccomp_send_sigill(); + return -1; case SECCOMP_RET_ALLOW: return 0; case SECCOMP_RET_KILL: -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/