[PATCH 5.15 036/667] ptrace/um: Replace PT_DTRACE with TIF_SINGLESTEP
From: Greg Kroah-Hartman
Date: Tue Jun 07 2022 - 14:18:37 EST
From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
commit c200e4bb44e80b343c09841e7caaaca0aac5e5fa upstream.
User mode linux is the last user of the PT_DTRACE flag. Using the flag to indicate
single stepping is a little confusing and worse changing tsk->ptrace without locking
could potentionally cause problems.
So use a thread info flag with a better name instead of flag in tsk->ptrace.
Remove the definition PT_DTRACE as uml is the last user.
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Tested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20220505182645.497868-3-ebiederm@xxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/um/include/asm/thread_info.h | 2 ++
arch/um/kernel/exec.c | 2 +-
arch/um/kernel/process.c | 2 +-
arch/um/kernel/ptrace.c | 8 ++++----
arch/um/kernel/signal.c | 4 ++--
include/linux/ptrace.h | 1 -
6 files changed, 10 insertions(+), 9 deletions(-)
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -64,6 +64,7 @@ static inline struct thread_info *curren
#define TIF_RESTORE_SIGMASK 7
#define TIF_NOTIFY_RESUME 8
#define TIF_SECCOMP 9 /* secure computing */
+#define TIF_SINGLESTEP 10 /* single stepping userspace */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
@@ -72,5 +73,6 @@ static inline struct thread_info *curren
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
+#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
#endif
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -42,7 +42,7 @@ void start_thread(struct pt_regs *regs,
{
PT_REGS_IP(regs) = eip;
PT_REGS_SP(regs) = esp;
- current->ptrace &= ~PT_DTRACE;
+ clear_thread_flag(TIF_SINGLESTEP);
#ifdef SUBARCH_EXECVE1
SUBARCH_EXECVE1(regs->regs);
#endif
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -339,7 +339,7 @@ int singlestepping(void * t)
{
struct task_struct *task = t ? t : current;
- if (!(task->ptrace & PT_DTRACE))
+ if (!test_thread_flag(TIF_SINGLESTEP))
return 0;
if (task->thread.singlestep_syscall)
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -12,7 +12,7 @@
void user_enable_single_step(struct task_struct *child)
{
- child->ptrace |= PT_DTRACE;
+ set_tsk_thread_flag(child, TIF_SINGLESTEP);
child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING
@@ -22,7 +22,7 @@ void user_enable_single_step(struct task
void user_disable_single_step(struct task_struct *child)
{
- child->ptrace &= ~PT_DTRACE;
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING
@@ -121,7 +121,7 @@ static void send_sigtrap(struct uml_pt_r
}
/*
- * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
+ * XXX Check TIF_SINGLESTEP for singlestepping check and
* PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
*/
int syscall_trace_enter(struct pt_regs *regs)
@@ -145,7 +145,7 @@ void syscall_trace_leave(struct pt_regs
audit_syscall_exit(regs);
/* Fake a debug trap */
- if (ptraced & PT_DTRACE)
+ if (test_thread_flag(TIF_SINGLESTEP))
send_sigtrap(®s->regs, 0);
if (!test_thread_flag(TIF_SYSCALL_TRACE))
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -53,7 +53,7 @@ static void handle_signal(struct ksignal
unsigned long sp;
int err;
- if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
+ if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED))
singlestep = 1;
/* Did we come from a system call? */
@@ -128,7 +128,7 @@ void do_signal(struct pt_regs *regs)
* on the host. The tracing thread will check this flag and
* PTRACE_SYSCALL if necessary.
*/
- if (current->ptrace & PT_DTRACE)
+ if (test_thread_flag(TIF_SINGLESTEP))
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(¤t->thread.regs));
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -30,7 +30,6 @@ extern int ptrace_access_vm(struct task_
#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */
#define PT_PTRACED 0x00000001
-#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
#define PT_OPT_FLAG_SHIFT 3
/* PT_TRACE_* event enable flags */