Re: [PATCH v11 10/12] ptrace,seccomp: Add PTRACE_SECCOMP support
From: Oleg Nesterov <oleg@redhat.com>
Date: 2012-02-27 18:02:36
Also in:
linux-arch, lkml
On 02/24, Will Drewry wrote:
arch/Kconfig | 1 + include/linux/ptrace.h | 7 +++++-- include/linux/seccomp.h | 4 +++- include/linux/tracehook.h | 6 ++++++ kernel/ptrace.c | 4 ++++ kernel/seccomp.c | 18 ++++++++++++++++++
FYI, this conflicts with the changes -mm tree. The changes in ptrace.* confict with Denys's "ptrace: simplify PTRACE_foo constants and PTRACE_SETOPTIONS code" The change in tracehook.h conflicts with "ptrace: the killed tracee should not enter the syscall"
quoted hunk ↗ jump to hunk
--- a/kernel/seccomp.c +++ b/kernel/seccomp.c@@ -354,6 +354,24 @@ int __secure_computing_int(int this_syscall) seccomp_send_sigsys(this_syscall, reason_code); return -1; } + case SECCOMP_RET_TRACE: { + int ret; + struct pt_regs *regs = task_pt_regs(current); + if (!(test_tsk_thread_flag(current, TIF_SYSCALL_TRACE)) || + !(current->ptrace & PT_TRACE_SECCOMP)) + return -1; + /* + * PT_TRACE_SECCOMP and seccomp.trace indicate whether + * tracehook_report_syscall_entry needs to signal the + * tracer. This avoids race conditions in hand off and + * the requirement for TIF_SYSCALL_TRACE ensures that + * we are in the syscall slow path. + */ + current->seccomp.trace = 1; + ret = tracehook_report_syscall_entry(regs); + current->seccomp.trace = 0; + return ret;
To be honest, this interface looks a bit strange to me... Once again, sorry if this was already discussed. But perhaps it would be better to introduce PTRACE_EVENT_SECCOMP/PTRACE_O_SECCOMP instead? SECCOMP_RET_TRACE: could simply do ptrace_event(PTRACE_EVENT_SECCOMP) unconditionaly. The tracer can set the option and do PTRACE_CONT if it doesn't want the system call notifications. This is also much simpler, no need to change ptrace/tracehook files. Oleg.