| Message ID | 1391410590-4884-4-git-send-email-takahiro.akashi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <takahiro.akashi@linaro.org> > --- > 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. > 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. Will
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 <takahiro.akashi@linaro.org> >> --- >> 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 >
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 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]); + if (!test_thread_flag(TIF_SYSCALL_TRACE)) return regs->syscallno;
This patch adds auditing functions on entry to or exit from every system call invocation. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- 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(+)