On 02/05/2014 02:31 AM, Will Deacon wrote:
On Mon, Feb 03, 2014 at 06:56:30AM +0000, AKASHI Takahiro wrote:
This patch adds auditing functions on entry to or exit from
every system call invocation.
Signed-off-by: AKASHI Takahiro <[email protected]>
---
arch/arm64/include/asm/thread_info.h | 1 +
arch/arm64/kernel/entry.S | 3 +++
arch/arm64/kernel/ptrace.c | 10 ++++++++++
3 files changed, 14 insertions(+)
diff --git a/arch/arm64/include/asm/thread_info.h
b/arch/arm64/include/asm/thread_info.h
index 720e70b..7468388 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -101,6 +101,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
#define TIF_SYSCALL_TRACE 8
+#define TIF_SYSCALL_AUDIT 9
#define TIF_POLLING_NRFLAG 16
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
#define TIF_FREEZE 19
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 827cbad..83c4b29 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -630,6 +630,9 @@ el0_svc_naked: //
compat entry point
get_thread_info tsk
ldr x16, [tsk, #TI_FLAGS] // check for syscall tracing
tbnz x16, #TIF_SYSCALL_TRACE, __sys_trace // are we tracing syscalls?
+#ifdef CONFIG_AUDITSYSCALL
+ tbnz x16, #TIF_SYSCALL_AUDIT, __sys_trace // auditing syscalls?
+#endif
Could we avoid the back-to-back tbnz instructions with a single mask? It's
not obvious that it will end up any better, but it would be good to know.
When first implementing ftrace support, TIF_SYSCALL_TRACEPOINT is defined as 10
and 'tst' instruction doesn't allow the following code:
tst x16, #(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_TRACEPOINT)
That is why I've used "back-to-back" tbnz since then, but now that I'm going to
submit ftrace, audit and later seccomp, I will replace it with:
#define TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE|TRACEPOINT|AUDIT|SECCOMP)
tst x16, #TIF_SYSCALL_WORK
b.ne __syscall_trace
adr lr, ret_fast_syscall // return address
cmp scno, sc_nr // check upper syscall limit
b.hs ni_sys
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 6777a21..75a3f23 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -19,6 +19,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/audit.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
@@ -38,6 +39,7 @@
#include <asm/compat.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
+#include <asm/syscall.h>
#include <asm/traps.h>
#include <asm/system_misc.h>
@@ -1064,6 +1066,14 @@ asmlinkage int syscall_trace(int dir, struct pt_regs
*regs)
{
unsigned long saved_reg;
+ if (dir)
+ audit_syscall_exit(regs);
+ else
+ audit_syscall_entry(syscall_get_arch(current, regs),
+ (int)regs->syscallno,
+ regs->orig_x0, regs->regs[1],
+ regs->regs[2], regs->regs[3]);
+
Do we really want to perform the audit checks before the tracehook calls?
Remember that the latter can rewrite all of the registers.
OK. I will change the code to make calls in the following order:
On entry,
*secure_computing
*tracehook_report_syscall(ENTER)
*trace_sys_enter
*audit_syscall_entry
On exit,
*audit_syscall_exit
*trace_sys_exit
*tracehook_report_syscall(EXIT)
The order here is the exact same as on x86, but such change might
decrease the readability in syscall_trace().
Thanks,
-Takahiro AKASHI
Will
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