From 4b38a59ff304d7d0b7a1ec8c7fe01a92a4b3ed10 Mon Sep 17 00:00:00 2001 From: Will Drewry Date: Thu, 9 Feb 2012 11:28:23 -0600 Subject: UBUNTU: SAUCE: SECCOMP: 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 Signed-off-by: Kees Cook --- arch/x86/Kconfig | 3 ++- arch/x86/kernel/ptrace.c | 7 ++++++- 2 files changed, 8 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index e32329977f5..faab3f5cf81 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -81,7 +81,8 @@ config X86 select CLKEVT_I8253 select ARCH_HAVE_NMI_SAFE_CMPXCHG select GENERIC_IOMAP - select DCACHE_WORD_ACCESS + select DCACHE_WORD_ACCESS if !DEBUG_PAGEALLOC + select HAVE_ARCH_SECCOMP_FILTER config INSTRUCTION_DECODER def_bool (KPROBES || PERF_EVENTS) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 685845cf16e..13b1990c7c5 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -1480,7 +1480,11 @@ 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; @@ -1505,6 +1509,7 @@ long syscall_trace_enter(struct pt_regs *regs) regs->dx, regs->r10); #endif +out: return ret ?: regs->orig_ax; } -- cgit v1.2.3