Add CONFIG_AUDITSC and CONFIG_SECCOMP support for ppc32

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

4 files changed, 62 insertions, 13 deletions

diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig
index 600f23d..cd752a3 100644
--- a/arch/ppc/Kconfig
+++ b/arch/ppc/Kconfig
@@ -1083,6 +1083,23 @@ source "drivers/zorro/Kconfig"
 
 source kernel/power/Kconfig
 
+config SECCOMP
+	bool "Enable seccomp to safely compute untrusted bytecode"
+	depends on PROC_FS
+	default y
+	help
+	  This kernel feature is useful for number crunching applications
+	  that may need to compute untrusted bytecode during their
+	  execution. By using pipes or other transports made available to
+	  the process as file descriptors supporting the read/write
+	  syscalls, it's possible to isolate those applications in
+	  their own address space using seccomp. Once seccomp is
+	  enabled via /proc/<pid>/seccomp, it cannot be disabled
+	  and the task is only allowed to execute a few safe syscalls
+	  defined by each seccomp mode.
+
+	  If unsure, say Y. Only embedded should say N here.
+
 endmenu
 
 config ISA_DMA_API
diff --git a/arch/ppc/kernel/entry.S b/arch/ppc/kernel/entry.S
index 5f075db..6615237 100644
--- a/arch/ppc/kernel/entry.S
+++ b/arch/ppc/kernel/entry.S
@@ -202,7 +202,7 @@ _GLOBAL(DoSyscall)
 	rlwinm	r11,r11,0,~_TIFL_FORCE_NOERROR
 	stw	r11,TI_LOCAL_FLAGS(r10)
 	lwz	r11,TI_FLAGS(r10)
-	andi.	r11,r11,_TIF_SYSCALL_TRACE
+	andi.	r11,r11,_TIF_SYSCALL_T_OR_A
 	bne-	syscall_dotrace
 syscall_dotrace_cont:
 	cmplwi	0,r0,NR_syscalls
@@ -237,7 +237,7 @@ ret_from_syscall:
 	SYNC
 	MTMSRD(r10)
 	lwz	r9,TI_FLAGS(r12)
-	andi.	r0,r9,(_TIF_SYSCALL_TRACE|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
+	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
 	bne-	syscall_exit_work
 syscall_exit_cont:
 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
@@ -277,7 +277,8 @@ syscall_dotrace:
 	SAVE_NVGPRS(r1)
 	li	r0,0xc00
 	stw	r0,TRAP(r1)
-	bl	do_syscall_trace
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	do_syscall_trace_enter
 	lwz	r0,GPR0(r1)	/* Restore original registers */
 	lwz	r3,GPR3(r1)
 	lwz	r4,GPR4(r1)
@@ -291,7 +292,7 @@ syscall_dotrace:
 syscall_exit_work:
 	stw	r6,RESULT(r1)	/* Save result */
 	stw	r3,GPR3(r1)	/* Update return value */
-	andi.	r0,r9,_TIF_SYSCALL_TRACE
+	andi.	r0,r9,_TIF_SYSCALL_T_OR_A
 	beq	5f
 	ori	r10,r10,MSR_EE
 	SYNC
@@ -303,7 +304,8 @@ syscall_exit_work:
 	li	r4,0xc00
 	stw	r4,TRAP(r1)
 4:
-	bl	do_syscall_trace
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	bl	do_syscall_trace_leave
 	REST_NVGPRS(r1)
 2:
 	lwz	r3,GPR3(r1)
@@ -627,8 +629,8 @@ sigreturn_exit:
 	subi	r1,r3,STACK_FRAME_OVERHEAD
 	rlwinm	r12,r1,0,0,18	/* current_thread_info() */
 	lwz	r9,TI_FLAGS(r12)
-	andi.	r0,r9,_TIF_SYSCALL_TRACE
-	bnel-	do_syscall_trace
+	andi.	r0,r9,_TIF_SYSCALL_T_OR_A
+	bnel-	do_syscall_trace_leave
 	/* fall through */
 
 	.globl	ret_from_except_full
diff --git a/arch/ppc/kernel/ppc_ksyms.c b/arch/ppc/kernel/ppc_ksyms.c
index 2ccb58f..d59ad07 100644
--- a/arch/ppc/kernel/ppc_ksyms.c
+++ b/arch/ppc/kernel/ppc_ksyms.c
@@ -55,7 +55,6 @@
 #define EXPORT_SYMTAB_STROPS
 
 extern void transfer_to_handler(void);
-extern void do_syscall_trace(void);
 extern void do_IRQ(struct pt_regs *regs);
 extern void MachineCheckException(struct pt_regs *regs);
 extern void AlignmentException(struct pt_regs *regs);
@@ -74,7 +73,6 @@ extern unsigned long mm_ptov (unsigned long paddr);
 EXPORT_SYMBOL(clear_pages);
 EXPORT_SYMBOL(clear_user_page);
 EXPORT_SYMBOL(do_signal);
-EXPORT_SYMBOL(do_syscall_trace);
 EXPORT_SYMBOL(transfer_to_handler);
 EXPORT_SYMBOL(do_IRQ);
 EXPORT_SYMBOL(MachineCheckException);
diff --git a/arch/ppc/kernel/ptrace.c b/arch/ppc/kernel/ptrace.c
index 59d59a8..e7aee41 100644
--- a/arch/ppc/kernel/ptrace.c
+++ b/arch/ppc/kernel/ptrace.c
@@ -27,6 +27,9 @@
 #include <linux/user.h>
 #include <linux/security.h>
 #include <linux/signal.h>
+#include <linux/seccomp.h>
+#include <linux/audit.h>
+#include <linux/module.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
@@ -455,11 +458,10 @@ out:
 	return ret;
 }
 
-void do_syscall_trace(void)
+static void do_syscall_trace(void)
 {
-        if (!test_thread_flag(TIF_SYSCALL_TRACE)
-	    || !(current->ptrace & PT_PTRACED))
-		return;
+	/* the 0x80 provides a way for the tracing parent to distinguish
+	   between a syscall stop and SIGTRAP delivery */
 	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 				 ? 0x80 : 0));
 
@@ -473,3 +475,33 @@ void do_syscall_trace(void)
 		current->exit_code = 0;
 	}
 }
+
+void do_syscall_trace_enter(struct pt_regs *regs)
+{
+	if (test_thread_flag(TIF_SYSCALL_TRACE)
+	    && (current->ptrace & PT_PTRACED))
+		do_syscall_trace();
+
+	if (unlikely(current->audit_context))
+		audit_syscall_entry(current, AUDIT_ARCH_PPC,
+				    regs->gpr[0],
+				    regs->gpr[3], regs->gpr[4],
+				    regs->gpr[5], regs->gpr[6]);
+}
+
+void do_syscall_trace_leave(struct pt_regs *regs)
+{
+	secure_computing(regs->gpr[0]);
+
+	if (unlikely(current->audit_context))
+		audit_syscall_exit(current,
+				   (regs->ccr&0x1000)?AUDITSC_FAILURE:AUDITSC_SUCCESS,
+				   regs->result);
+
+	if ((test_thread_flag(TIF_SYSCALL_TRACE))
+	    && (current->ptrace & PT_PTRACED))
+		do_syscall_trace();
+}
+
+EXPORT_SYMBOL(do_syscall_trace_enter);
+EXPORT_SYMBOL(do_syscall_trace_leave);