diff options
Diffstat (limited to 'arch/i386')
| -rw-r--r-- | arch/i386/kernel/entry.S | 9 | ||||
| -rw-r--r-- | arch/i386/kernel/ptrace.c | 57 |
2 files changed, 45 insertions, 21 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index a991d4e5edd2..b389e5f3bdee 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -203,7 +203,7 @@ sysenter_past_esp: GET_THREAD_INFO(%ebp) /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */ - testw $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),TI_flags(%ebp) + testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp) jnz syscall_trace_entry cmpl $(nr_syscalls), %eax jae syscall_badsys @@ -226,9 +226,9 @@ ENTRY(system_call) pushl %eax # save orig_eax SAVE_ALL GET_THREAD_INFO(%ebp) - # system call tracing in operation + # system call tracing in operation / emulation /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */ - testw $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),TI_flags(%ebp) + testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp) jnz syscall_trace_entry cmpl $(nr_syscalls), %eax jae syscall_badsys @@ -338,6 +338,9 @@ syscall_trace_entry: movl %esp, %eax xorl %edx,%edx call do_syscall_trace + cmpl $0, %eax + jne syscall_exit # ret != 0 -> running under PTRACE_SYSEMU, + # so must skip actual syscall movl ORIG_EAX(%esp), %eax cmpl $(nr_syscalls), %eax jnae syscall_call diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c index 5ee9e1d60653..5b569dc1c227 100644 --- a/arch/i386/kernel/ptrace.c +++ b/arch/i386/kernel/ptrace.c @@ -509,15 +509,27 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data) } break; + case PTRACE_SYSEMU: /* continue and stop at next syscall, which will not be executed */ case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ case PTRACE_CONT: /* restart after signal. */ ret = -EIO; if (!valid_signal(data)) break; + /* If we came here with PTRACE_SYSEMU and now continue with + * PTRACE_SYSCALL, entry.S used to intercept the syscall return. + * But it shouldn't! + * So we don't clear TIF_SYSCALL_EMU, which is always unused in + * this special case, to remember, we came from SYSEMU. That + * flag will be cleared by do_syscall_trace(). + */ + if (request == PTRACE_SYSEMU) { + set_tsk_thread_flag(child, TIF_SYSCALL_EMU); + } else if (request == PTRACE_CONT) { + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); + } if (request == PTRACE_SYSCALL) { set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); - } - else { + } else { clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); } child->exit_code = data; @@ -546,6 +558,8 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data) ret = -EIO; if (!valid_signal(data)) break; + /*See do_syscall_trace to know why we don't clear + * TIF_SYSCALL_EMU.*/ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); set_singlestep(child); child->exit_code = data; @@ -678,37 +692,43 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code) * - triggered by current->work.syscall_trace */ __attribute__((regparm(3))) -void do_syscall_trace(struct pt_regs *regs, int entryexit) +int do_syscall_trace(struct pt_regs *regs, int entryexit) { + int is_sysemu, is_systrace, is_singlestep, ret = 0; /* do the secure computing check first */ secure_computing(regs->orig_eax); - if (unlikely(current->audit_context)) { - if (entryexit) - audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); - - /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only - * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is - * not used, entry.S will call us only on syscall exit, not - * entry ; so when TIF_SYSCALL_AUDIT is used we must avoid - * calling send_sigtrap() on syscall entry. - */ - else if (is_singlestep) - goto out; - } + if (unlikely(current->audit_context) && entryexit) + audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); if (!(current->ptrace & PT_PTRACED)) goto out; + is_sysemu = test_thread_flag(TIF_SYSCALL_EMU); + is_systrace = test_thread_flag(TIF_SYSCALL_TRACE); + is_singlestep = test_thread_flag(TIF_SINGLESTEP); + + /* We can detect the case of coming from PTRACE_SYSEMU and now running + * with PTRACE_SYSCALL or PTRACE_SINGLESTEP, by TIF_SYSCALL_EMU being + * set additionally. + * If so let's reset the flag and return without action (no singlestep + * nor syscall tracing, since no actual step has been executed). + */ + if (is_sysemu && (is_systrace || is_singlestep)) { + clear_thread_flag(TIF_SYSCALL_EMU); + goto out; + } + /* Fake a debug trap */ if (test_thread_flag(TIF_SINGLESTEP)) send_sigtrap(current, regs, 0); - if (!test_thread_flag(TIF_SYSCALL_TRACE)) + if (!is_systrace && !is_sysemu) goto out; /* the 0x80 provides a way for the tracing parent to distinguish between a syscall stop and SIGTRAP delivery */ + /* Note that the debugger could change the result of test_thread_flag!*/ ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0)); /* @@ -720,9 +740,10 @@ void do_syscall_trace(struct pt_regs *regs, int entryexit) send_sig(current->exit_code, current, 1); current->exit_code = 0; } + ret = is_sysemu; out: if (unlikely(current->audit_context) && !entryexit) audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax, regs->ebx, regs->ecx, regs->edx, regs->esi); - + return ret; } |