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-rw-r--r--arch/i386/kernel/entry.S9
-rw-r--r--arch/i386/kernel/ptrace.c57
-rw-r--r--include/asm-i386/thread_info.h5
-rw-r--r--include/linux/ptrace.h1
-rw-r--r--kernel/fork.c3
5 files changed, 53 insertions, 22 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index a991d4e..b389e5f3 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 5ee9e1d..5b569dc 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;
}
diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h
index 95add81..e2cb9fa 100644
--- a/include/asm-i386/thread_info.h
+++ b/include/asm-i386/thread_info.h
@@ -139,6 +139,7 @@ register unsigned long current_stack_pointer asm("esp") __attribute_used__;
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_IRET 5 /* return with iret */
+#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
@@ -150,13 +151,15 @@ register unsigned long current_stack_pointer asm("esp") __attribute_used__;
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_IRET (1<<TIF_IRET)
+#define _TIF_SYSCALL_EMU (1<<TIF_SYSCALL_EMU)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
- (0x0000FFFF & ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP|_TIF_SECCOMP))
+ (0x0000FFFF & ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP|\
+ _TIF_SECCOMP|_TIF_SYSCALL_EMU))
/* work to do on any return to u-space */
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index a373fc2..7528afb 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -20,6 +20,7 @@
#define PTRACE_DETACH 0x11
#define PTRACE_SYSCALL 24
+#define PTRACE_SYSEMU 31
/* 0x4200-0x4300 are reserved for architecture-independent additions. */
#define PTRACE_SETOPTIONS 0x4200
diff --git a/kernel/fork.c b/kernel/fork.c
index b65187f..7e1ead9 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -994,6 +994,9 @@ static task_t *copy_process(unsigned long clone_flags,
* of CLONE_PTRACE.
*/
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+#ifdef TIF_SYSCALL_EMU
+ clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
+#endif
/* Our parent execution domain becomes current domain
These must match for thread signalling to apply */
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