Syscall auditing and seccomp for PPC32.
David Woodhouse
dwmw2 at infradead.org
Mon May 9 01:07:03 EST 2005
For information (and feedback) only. Do not apply; it's already in
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/dwmw2/audit-2.6.git
Why _is_ do_syscall_trace() exported, anyway?
Index: arch/ppc/Kconfig
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/arch/ppc/Kconfig (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/arch/ppc/Kconfig (mode:100644)
@@ -1083,6 +1083,23 @@
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
Index: arch/ppc/kernel/entry.S
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/arch/ppc/kernel/entry.S (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/arch/ppc/kernel/entry.S (mode:100644)
@@ -202,7 +202,7 @@
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 @@
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 @@
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_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 @@
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 @@
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
Index: arch/ppc/kernel/ppc_ksyms.c
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/arch/ppc/kernel/ppc_ksyms.c (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/arch/ppc/kernel/ppc_ksyms.c (mode:100644)
@@ -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 @@
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);
Index: arch/ppc/kernel/ptrace.c
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/arch/ppc/kernel/ptrace.c (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/arch/ppc/kernel/ptrace.c (mode:100644)
@@ -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 @@
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 @@
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);
Index: include/asm-ppc/thread_info.h
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/include/asm-ppc/thread_info.h (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/include/asm-ppc/thread_info.h (mode:100644)
@@ -77,12 +77,19 @@
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */
+#define TIF_SECCOMP 7 /* secure computing */
+
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
+#define _TIF_SECCOMP (1<<TIF_SECCOMP)
+
+#define _TIF_SYSCALL_T_OR_A (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)
/*
* Non racy (local) flags bit numbers
Index: init/Kconfig
===================================================================
--- 6cdd9771bd9a56de1b0246a330ccd916ecdb1d41/init/Kconfig (mode:100644)
+++ 27383b18b9f62d3c4f1b5dd9f3daeffb10416c15/init/Kconfig (mode:100644)
@@ -173,7 +173,7 @@
config AUDITSYSCALL
bool "Enable system-call auditing support"
- depends on AUDIT && (X86 || PPC64 || ARCH_S390 || IA64 || UML)
+ depends on AUDIT && (X86 || PPC || PPC64 || ARCH_S390 || IA64 || UML)
default y if SECURITY_SELINUX
help
Enable low-overhead system-call auditing infrastructure that
--
dwmw2
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