Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754032Ab2BVIeu (ORCPT ); Wed, 22 Feb 2012 03:34:50 -0500 Received: from smarthost1.greenhost.nl ([195.190.28.78]:57646 "EHLO smarthost1.greenhost.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752755Ab2BVIer (ORCPT ); Wed, 22 Feb 2012 03:34:47 -0500 Message-ID: <9edbabb2262e3d91a7b8c75dbec03d7f.squirrel@webmail.greenhost.nl> In-Reply-To: <1329845435-2313-7-git-send-email-wad@chromium.org> References: <1329845435-2313-1-git-send-email-wad@chromium.org> <1329845435-2313-7-git-send-email-wad@chromium.org> Date: Wed, 22 Feb 2012 09:34:42 +0100 Subject: Re: [PATCH v10 07/11] signal, x86: add SIGSYS info and make it synchronous. From: "Indan Zupancic" To: "Will Drewry" Cc: linux-kernel@vger.kernel.org, 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, pmoore@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com, markus@chromium.org, keescook@chromium.org, "Will Drewry" User-Agent: SquirrelMail/1.4.22 MIME-Version: 1.0 Content-Type: text/plain;charset=UTF-8 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-Spam-Score: 0.1 X-Scan-Signature: f0e1c9854a9562d49e95611d158cd3d0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5276 Lines: 157 On Tue, February 21, 2012 18:30, Will Drewry wrote: > This change enables SIGSYS, defines _sigfields._sigsys, and adds > x86 (compat) arch support. _sigsys defines fields which allow > a signal handler to receive the triggering system call number, > the relevant AUDIT_ARCH_* value for that number, and the address > of the callsite. > > To ensure that SIGSYS delivery occurs on return from the triggering > system call, SIGSYS is added to the SYNCHRONOUS_MASK macro. I'm > this is enough to ensure it will be synchronous or if it is explicitly > required to ensure an immediate delivery of the signal upon return from > the blocked system call. > > The first consumer of SIGSYS would be seccomp filter. In particular, > a filter program could specify a new return value, SECCOMP_RET_TRAP, > which would result in the system call being denied and the calling > thread signaled. This also means that implementing arch-specific > support can be dependent upon HAVE_ARCH_SECCOMP_FILTER. I think others said this is useful, but I don't see how. Easier debugging compared to checking return values? I suppose SIGSYS can be blocked, so there is no guarantee the process will be killed. > v10: - first version based on suggestion > > Suggested-by: H. Peter Anvin > Signed-off-by: Will Drewry > --- > arch/x86/ia32/ia32_signal.c | 4 ++++ > arch/x86/include/asm/ia32.h | 6 ++++++ > include/asm-generic/siginfo.h | 18 ++++++++++++++++++ > kernel/signal.c | 2 +- > 4 files changed, 29 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c > index 6557769..c81d2c7 100644 > --- a/arch/x86/ia32/ia32_signal.c > +++ b/arch/x86/ia32/ia32_signal.c > @@ -73,6 +73,10 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t > *from) > switch (from->si_code >> 16) { > case __SI_FAULT >> 16: > break; > + case __SI_SYS >> 16: > + put_user_ex(from->si_syscall, &to->si_syscall); > + put_user_ex(from->si_arch, &to->si_arch); > + break; > case __SI_CHLD >> 16: > put_user_ex(from->si_utime, &to->si_utime); > put_user_ex(from->si_stime, &to->si_stime); > diff --git a/arch/x86/include/asm/ia32.h b/arch/x86/include/asm/ia32.h > index 1f7e625..541485f 100644 > --- a/arch/x86/include/asm/ia32.h > +++ b/arch/x86/include/asm/ia32.h > @@ -126,6 +126,12 @@ typedef struct compat_siginfo { > int _band; /* POLL_IN, POLL_OUT, POLL_MSG */ > int _fd; > } _sigpoll; > + > + struct { > + unsigned int _call_addr; /* calling insn */ Why an int here, but a pointer below? > + int _syscall; /* triggering system call number */ > + unsigned int _arch; /* AUDIT_ARCH_* of syscall */ > + } _sigsys; > } _sifields; > } compat_siginfo_t; > > diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h > index 0dd4e87..a83b478 100644 > --- a/include/asm-generic/siginfo.h > +++ b/include/asm-generic/siginfo.h > @@ -90,6 +90,13 @@ typedef struct siginfo { > __ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */ > int _fd; > } _sigpoll; > + > + /* SIGSYS */ > + struct { > + void __user *_call_addr; /* calling insn */ Is this a user instruction pointer or a filter instruction? > + int _syscall; /* triggering system call number */ > + unsigned int _arch; /* AUDIT_ARCH_* of syscall */ > + } _sigsys; > } _sifields; > } siginfo_t; > > @@ -116,6 +123,9 @@ typedef struct siginfo { > #define si_addr_lsb _sifields._sigfault._addr_lsb > #define si_band _sifields._sigpoll._band > #define si_fd _sifields._sigpoll._fd > +#define si_call_addr _sifields._sigsys._call_addr > +#define si_syscall _sifields._sigsys._syscall > +#define si_arch _sifields._sigsys._arch > > #ifdef __KERNEL__ > #define __SI_MASK 0xffff0000u > @@ -126,6 +136,7 @@ typedef struct siginfo { > #define __SI_CHLD (4 << 16) > #define __SI_RT (5 << 16) > #define __SI_MESGQ (6 << 16) > +#define __SI_SYS (7 << 16) > #define __SI_CODE(T,N) ((T) | ((N) & 0xffff)) > #else > #define __SI_KILL 0 > @@ -135,6 +146,7 @@ typedef struct siginfo { > #define __SI_CHLD 0 > #define __SI_RT 0 > #define __SI_MESGQ 0 > +#define __SI_SYS 0 > #define __SI_CODE(T,N) (N) > #endif > > @@ -232,6 +244,12 @@ typedef struct siginfo { > #define NSIGPOLL 6 > > /* > + * SIGSYS si_codes > + */ > +#define SYS_SECCOMP (__SI_SYS|1) /* seccomp triggered */ > +#define NSIGSYS 1 > + > +/* > * sigevent definitions > * > * It seems likely that SIGEV_THREAD will have to be handled from > diff --git a/kernel/signal.c b/kernel/signal.c > index c73c428..7573819 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -160,7 +160,7 @@ void recalc_sigpending(void) > > #define SYNCHRONOUS_MASK \ > (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ > - sigmask(SIGTRAP) | sigmask(SIGFPE)) > + sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) > > int next_signal(struct sigpending *pending, sigset_t *mask) > { > -- Greetings, Indan -- 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/