Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 29 Feb 2012 17:53:38 -0600
From: Will Drewry <wad@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: linux-arch@...r.kernel.org,
	linux-doc@...r.kernel.org,
	kernel-hardening@...ts.openwall.com,
	netdev@...r.kernel.org,
	x86@...nel.org,
	arnd@...db.de,
	davem@...emloft.net,
	hpa@...or.com,
	mingo@...hat.com,
	oleg@...hat.com,
	peterz@...radead.org,
	rdunlap@...otime.net,
	mcgrathr@...omium.org,
	tglx@...utronix.de,
	luto@....edu,
	eparis@...hat.com,
	serge.hallyn@...onical.com,
	djm@...drot.org,
	scarybeasts@...il.com,
	indan@....nu,
	pmoore@...hat.com,
	akpm@...ux-foundation.org,
	corbet@....net,
	eric.dumazet@...il.com,
	markus@...omium.org,
	coreyb@...ux.vnet.ibm.com,
	keescook@...omium.org,
	Will Drewry <wad@...omium.org>
Subject: [PATCH v12 11/13] x86: Enable HAVE_ARCH_SECCOMP_FILTER

Enable support for seccomp filter on x86:
- asm/tracehook.h exists
- syscall_get_arguments() works
- syscall_rollback() works
- ptrace_report_syscall() works
- secure_computing() return value is honored (see below)

This also adds support for honoring the return
value from secure_computing().

SECCOMP_RET_TRACE and SECCOMP_RET_TRAP may result in seccomp needing to
skip a system call without killing the process.  This is done by
returning a non-zero (-1) value from secure_computing.  This change
makes x86 respect that return value.

To ensure that minimal kernel code is exposed, a non-zero return value
results in an immediate return to user space (with an invalid syscall
number).

Signed-off-by: Will Drewry <wad@...omium.org>
---
 arch/x86/Kconfig         |    1 +
 arch/x86/kernel/ptrace.c |    7 ++++++-
 2 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f50b52a..fe35491 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -81,6 +81,7 @@ config X86
 	select CLKEVT_I8253
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select GENERIC_IOMAP
+	select HAVE_ARCH_SECCOMP_FILTER
 
 config INSTRUCTION_DECODER
 	def_bool (KPROBES || PERF_EVENTS || UPROBES)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 78f05e4..cdce22c 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1381,7 +1381,11 @@ long syscall_trace_enter(struct pt_regs *regs)
 		regs->flags |= X86_EFLAGS_TF;
 
 	/* do the secure computing check first */
-	secure_computing(regs->orig_ax);
+	if (secure_computing(regs->orig_ax)) {
+		/* seccomp failures shouldn't expose any additional code. */
+		ret = -1L;
+		goto out;
+	}
 
 	if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
 		ret = -1L;
@@ -1406,6 +1410,7 @@ long syscall_trace_enter(struct pt_regs *regs)
 				    regs->dx, regs->r10);
 #endif
 
+out:
 	return ret ?: regs->orig_ax;
 }
 
-- 
1.7.5.4

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.